From popserver Wed Nov 1 17:00:42 GMT 1995 X-VM-Summary-Format: "%n %*%a %-17.17F %-3.3m %2d %4l/%-5c %I\"%s\"\n" X-VM-Labels: nil X-VM-VHeader: ("Resent-" "From:" "Sender:" "To:" "Apparently-To:" "Cc:" "Subject:" "Date:") nil X-VM-Bookmark: 146 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1198" "Wed" "1" "November" "1995" "15:50:49" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "28" "Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA17141; Wed, 1 Nov 95 06:50:42 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA01408 (5.67b/IDA-1.5 for ); Wed, 1 Nov 1995 15:50:19 +0100 Message-Id: <199511011450.AA01408@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl (Unverified) X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815245202.002 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, hedmarc@cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Mini SD-newsletter Date: Wed, 01 Nov 1995 15:50:49 +0100 Subject: Pre-loading the decell track >From : Timothy To : Kelly and Others >>> The idea of pre-launcing fuel (brought up by Timothy >>> VanderLinden et. al.) is great for getting up to speed, but >>> I want to see how they intend to pre-load the decell track. >> >> Hey that was my idea! I agree with the problem with a decel track thou. If >> we could do that the ship systems would be a snap. > >I know it was your idea, but they brought it up most recently and also >said they had the math to back it up. "Sure would like to see it", thats what I told Nick. Nick and I discussed a lot about that, but REAL maths were not involved as far as I knew. This does not mean that we didn't agree. Pre-loading the decelleration track would not be troublesome if one could aim the "cannon"/"lineac" precise enough. But about this aiming problem we did not agree. If it is not clear to anyone how to pre-load the decell track, assuming there is no aiming problem, I wouldn't mind to explain, just ask me some specific questions. Greetings Timothy P.S. My name is Timothy van der Linden, I'm a real Dutchman so the contraction to "VanderLinden" does not apply. From popserver Thu Nov 2 00:41:33 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1343" "Wed" "1" "November" "1995" "19:35:37" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "30" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA23961; Wed, 1 Nov 95 16:35:18 PST Received: by mail06.mail.aol.com (8.6.12/8.6.12) id TAA09236; Wed, 1 Nov 1995 19:35:37 -0500 Message-Id: <951101193537_10158014@mail06.mail.aol.com> X-UIDL: 815272853.000 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, hedmarc@cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Mini SD-newsletter Date: Wed, 1 Nov 1995 19:35:37 -0500 >>> The idea of pre-launcing fuel (brought up by Timothy >>> VanderLinden et. al.) is great for getting up to speed, but >>> I want to see how they intend to pre-load the decell track. >> >> Hey that was my idea! I agree with the problem with a decel track thou. If >> we could do that the ship systems would be a snap. > >I know it was your idea, but they brought it up most recently and also >said they had the math to back it up. >> "Sure would like to see it", thats what I told Nick. Nick and >> I discussed a lot about that, but REAL maths were not >> involved as far as I knew. This does not mean that we >> didn't agree. Pre-loading the decelleration track would >> not be troublesome if one could aim the "cannon"/" >> lineac" precise enough. But about this aiming problem >> we did not agree. If it is not clear to anyone how to >> pre-load the decell track, assuming there is no aiming >> problem, I wouldn't mind to explain, just ask me some >> specific questions. Hi Tim, Ok, how do you get the decel fuel in the Target star systems decel track, and at an acceptable speed? To get their befor the ship it would have to be going at relativistic speeds. But if its going that fast, the ship couldn't catch its decel fuel. i.e. the ship would slow down, but the fuel wouldn't. Kelly From popserver Fri Nov 3 17:03:03 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1836" "Fri" "3" "November" "1995" "17:14:59" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "35" "Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA18472; Fri, 3 Nov 95 08:15:38 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA20356 (5.67b/IDA-1.5 for ); Fri, 3 Nov 1995 17:14:44 +0100 Message-Id: <199511031614.AA20356@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815418109.015 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, hedmarc@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca, T.L.G.vanderLinden@student.utwente.nl Subject: Mini SD-newsletter Date: Fri, 03 Nov 1995 17:14:59 +0100 Subject: Pre-loading the decell track Author : Timothy ReplyTo: Kelly >Ok, how do you get the decel fuel in the Target star systems decel track, and >at an acceptable speed? To get their befor the ship it would have to be >going at relativistic speeds. But if its going that fast, the ship couldn't >catch its decel fuel. i.e. the ship would slow down, but the fuel wouldn't. Another way to get it at the target before the Asimov is to send it there before the Asimov is started. What I mean is that the slowest fuel-packets will be send from Earth many years before the Asimov starts moving to TC. These early packets have low speeds and thus take a long time to get to TC. Faster packets which will be catched up by the Asimov first will be send last but still before the Asimov has started. So now there is a long track of packets all at decreasing speeds. All these packets are moving towards TC and so is the Asimov, but the Asimov moves a little bit faster than the fastest moving packet and "near" TC it catches up with that packet. After catching that packet the Asimov slows down a bit, but not too much, so that it can catch up with the next packet which moved slower than the packet just catched. This process repeates many times, untill the Asimov has an reasonable slow velocity. Because all packets are launched before the Asimov starts we call it a PRE-load track. Now the trick is to have all packets at the right place at the right time and at the right speed. This surely would be possible if we could aim our lineac at Sol precise enough. Of course there is a minimum limit speed for the slowest and first package: The slower it moves the earlier it has to be send to TC. If we would need real slow packets we would need sending them now already. OK, I hope this is clear, if not, ask me once more. Timothy From popserver Fri Nov 3 17:03:07 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1940" "Fri" "3" "November" "1995" "08:36:45" "-0800" "Ric Hedman" "HEDMARC@cellpro.cellpro.com" nil "45" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from cellpro.com (mail.cellpro.com) by efn.efn.org (4.1/smail2.5/05-07-92) id AA19924; Fri, 3 Nov 95 08:37:56 PST Received: by cryovial.cellpro.com id <44801>; Fri, 3 Nov 1995 08:38:04 -0800 X-Nvlenv-01Date-Posted: 3-Nov-1995 8:36:54 -0800; at Bothell.CellPro In-Reply-To: <11009A30015C2979@-SMF-> References: <11009A30025C2979@-SMF-> Message-Id: <95Nov3.083804pst.44801@cryovial.cellpro.com> X-UIDL: 815418109.018 From: HEDMARC@cellpro.cellpro.com (Hedman, Ric) To: T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com Subject: Re: Mini SD-newsletter Date: Fri, 3 Nov 1995 08:36:45 -0800 >Another way to get it at the target before the Asimov is to send it there >before the Asimov is started. What I mean is that the slowest fuel-packets >will be send from Earth many years before the Asimov starts moving to TC. >These early packets have low speeds and thus take a long time to get to TC. >Faster packets which will be catched up by the Asimov first will be send >last but still before the Asimov has started. So now there is a long track >of packets all at decreasing speeds. All these packets are moving towards TC >and so is the Asimov, but the Asimov moves a little bit faster than the >fastest moving packet and "near" TC it catches up with that packet. After >catching that packet the Asimov slows down a bit, but not too much, so that >it can catch up with the next packet which moved slower than the packet just >catched. This process repeates many times, untill the Asimov has an >reasonable slow velocity. >Because all packets are launched before the Asimov starts we call it a >PRE-load track. Now the trick is to have all packets at the right place at >the right time and at the right speed. This surely would be possible if we >could aim our lineac at Sol precise enough. Of course there is a minimum >limit speed for the slowest and first package: The slower it moves the >earlier it has to be send to TC. If we would need real slow packets we would >need sending them now already. OK, so we have this traffic jamb of fuel cells in a long string heading to TC. Are the faster ones going to overtake the slower ones? How are these faster fuel cells going to avoid colliding with the slower ones. If you aim all these off by just little bits to avoid running up the tailpipe of the slower ones by the time you get close to TC they are fanned out all over the place. By the way I will up and running up at home tomorrow so you can send these to: rddesign@wolfenet.com from now on. Thanks Ric From popserver Sat Nov 4 06:32:07 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4854" "Sat" "4" "November" "1995" "00:29:38" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "95" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA14448; Fri, 3 Nov 95 22:30:32 PST Received: by maroon.tc.umn.edu; Sat, 4 Nov 95 00:29:39 -0600 In-Reply-To: <199511031614.AA20356@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 815466718.000 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, hedmarc@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Mini SD-newsletter Date: Sat, 4 Nov 1995 00:29:38 -0600 (CST) Subject: pre-loading the decell track Author: Kevin Houston Replying to Timothy > Subject: Pre-loading the decell track > Author : Timothy > ReplyTo: Kelly > > >Ok, how do you get the decel fuel in the Target star systems decel track, and > >at an acceptable speed? To get their befor the ship it would have to be > >going at relativistic speeds. But if its going that fast, the ship couldn't > >catch its decel fuel. i.e. the ship would slow down, but the fuel wouldn't. > > Another way to get it at the target before the Asimov is to send it there > before the Asimov is started. What I mean is that the slowest fuel-packets > will be send from Earth many years before the Asimov starts moving to TC. > These early packets have low speeds and thus take a long time to get to TC. > Faster packets which will be catched up by the Asimov first will be send > last but still before the Asimov has started. So now there is a long track > of packets all at decreasing speeds. All these packets are moving towards TC > and so is the Asimov, but the Asimov moves a little bit faster than the > fastest moving packet and "near" TC it catches up with that packet. After > catching that packet the Asimov slows down a bit, but not too much, so that > it can catch up with the next packet which moved slower than the packet just > catched. This process repeates many times, untill the Asimov has an > reasonable slow velocity. > Yes, but at some point in the deceleration we will have to be moving at some arbitraily slow speed, let's say for the sake of argument that we want to see how the "Asimov" gets fuel while moving at .01 C (a speed of 3 million meters a second) in order to get fuel to T.C. with a speed of 3E+06, it will have to be launched 1200 years before the ship! Even if you cut off the fuel supply at a speed of .1 C (and how can you slow down from this insane speed without fuel?) you'd need to launch fuel 120 years ahead of ship launch. The U.S. (or others by the way) political scene would never stay focused for that length of time. It's preety dicey as to whether or not they'd leave the maser beam alone for two years (earth time) never mind 120! I'm going to go out on a limb here and say that there is _no_ way you could pre-load the decell track of a target like Tau Ceti. Maybe, Just Maybe, You could do it for Alpha Centauri, but not Tau ceti. and since the target is Tau Ceti, we need a better way. Either beam the power, or figure out how to use the Interstellar Medium (ISM) as a brake. I say that beaming the power is the quickest easiest solution. To: all From: Kevin H. Re: Results of Vote (un official) Having looked through the replies (before the newsletter melted), it seemed that the majority opinion was for a continued presence at T.C. While this may seem unrealistic to some (shush Kelly ;) ) I think it is a reasonable goal. I don't think our job is to do an economic justification for the colony (or base) I think we only need to show that it is possible. If someone in the future should decide to use our design, I'm sure there will be many changes, and this is one of the first no doubt. So here is the proposal. 1) Purpose of the mission is to set up a permanent base at T.C. in order to study the system in-depth and possibly set up a colony if conditions warrant. Otherwise, the base is slated to be abandoned after all the research is done. Expected service life of base should be 50 Solar years, any permanant colony must be self-sufficient. 2) Some means of sustainable (closed-cycle) life support must be found. spare parts and supplies can be ferried (see #3 below) to T.C., but the daily bread must be home-grown. 3) Individual crew members must have a reasonable chance to get rotated back to earth and/or quit the mission at various intervals. i.e. , there must be regular "shuttle bus" service, and this must be cost effective 4) "Shuttle busses" can assume loaded accel and decel tracks, or conversly they can assume functioning maser transmitters in both systems. 5) The "Asimov" need not be returned to Earth, it can stay at T.C. and become the core of the base, it can be junked, or it can be fitted for another trip to some other star in the local neighborhood. if you intend to convert the "Asimov" to a base, please be specific in dual-use details. if you intend to refit it for another journey, how will you build the spacedock? what target would you select, and who will crew it? Maybe you have some other use for the "Asimov" (we could put a big sign on it that says "Colony ship for sale - Cheap!" if you don't get the joke, that just means you haven't played enough Marathon.) I think the next vote shold be on engine type, but that should probably wait until we can get the Newsletter back up and running. Kevin H. From popserver Sat Nov 4 17:26:46 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["831" "Sat" "4" "November" "1995" "16:00:58" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "21" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA27052; Sat, 4 Nov 95 07:01:02 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA12655 (5.67b/IDA-1.5 for ); Sat, 4 Nov 1995 16:00:54 +0100 Message-Id: <199511041500.AA12655@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815505969.014 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Mini SD-newsletter Date: Sat, 04 Nov 1995 16:00:58 +0100 Subject: Preloading the decel-track Author : Timothy ReplyTo: Ric >OK, so we have this traffic jamb of fuel cells in a long string heading >to TC. Are the faster ones going to overtake the slower ones? How are >these faster fuel cells going to avoid colliding with the slower ones. If >you aim all these off by just little bits to avoid running up the >tailpipe of the slower ones by the time you get close to TC they are >fanned out all over the place. No, the faster ones are NOT going to overtake the slower ones. But of course all packets get course the get nearer to each other all the time. In fact if they where not captured near TC they would indeed overtake each other. What we have to do is send them in the right intervals so they don't overtake before TC. So fanning out the packets is not necessary. Timothy From popserver Sat Nov 4 17:26:47 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5384" "Sat" "4" "November" "1995" "16:01:03" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "114" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA27056; Sat, 4 Nov 95 07:01:10 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA12661 (5.67b/IDA-1.5 for ); Sat, 4 Nov 1995 16:00:59 +0100 Message-Id: <199511041500.AA12661@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815505969.015 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Mini SD-newsletter Date: Sat, 04 Nov 1995 16:01:03 +0100 Subject: Pre-loading the decell track Author : Timothy ReplyTo: Kevin Houston >Yes, but at some point in the deceleration we will have to be moving at >some arbitraily slow speed, let's say for the sake of argument that we >want to see how the "Asimov" gets fuel while moving at .01 C (a speed of >3 million meters a second) in order to get fuel to T.C. with a speed of >3E+06, it will have to be launched 1200 years before the ship! I was aware of that problem and wrote it but you didn't quote that part, so I write it once more: < Of course there is a minimum limit speed for the slowest and first package: < The slower it moves the earlier it has to be send to TC. If we would need real < slow packets we would need sending them now already. I hadn't done any calculations, but am glad you did. Any speed less than top-speed would be a gain. 0.3c would be more acceptable with respect to 0.8c, but of course not enough. >Even if >you cut off the fuel supply at a speed of .1 C (and how can you slow down >from this insane speed without fuel?) OK you wonder how to decelerate even further? Easy, don't burn all the fuel from the packets as soon as you get a hold of them. OK, the ship gets a bit heavier and would be a bit more difficult to decelerate, but every system has some advantages. That extra bit of weight/fuel should be just enough to decelerate from 0.1c to 0.0c. >you'd need to launch fuel 120 years >ahead of ship launch. The U.S. (or others by the way) political scene >would never stay focused for that length of time. It's preety dicey as >to whether or not they'd leave the maser beam alone for two years (earth >time) never mind 120! Yes, 120 years is too much, but that would also mean that the energy costs would be spread over more years than using direct beaming. >I'm going to go out on a limb here and say that there is _no_ way you >could pre-load the decell track of a target like Tau Ceti. Maybe, Just >Maybe, You could do it for Alpha Centauri, but not Tau ceti. and since >the target is Tau Ceti, we need a better way. Either beam the power, or >figure out how to use the Interstellar Medium (ISM) as a brake. I say >that beaming the power is the quickest easiest solution. Hey I never said it was such a good idea, I only tried to show that pre-loading would be possible. As I am sure you know, both theories you mentioned have many hooks and eyes too. We still haven't done good calculations of what the energy costs would be for these theories. Timothy ------------------------------------------------------------------------- Subject: Results of Vote (un official) ReplyTo: Kevin H. Author : Timothy >Having looked through the replies (before the newsletter melted), it >seemed that the majority opinion was for a continued presence at T.C. >While this may seem unrealistic to some (shush Kelly ;) ) I think it is >a reasonable goal. I don't think our job is to do an economic >justification for the colony (or base) I think we only need to show that >it is possible. If someone in the future should decide to use our >design, I'm sure there will be many changes, and this is one of the first >no doubt. We "know" that it is possible, but don't ask at what cost. Economic justification depends on many things two of them are cost and profit. Going to TC at low cost (ie. slow speeds) means little profit (the "trip" takes a long time so the financiers would not be alive anymore). And even higher costs are not sure to give real profits. What I meant to say is that we not should loose all economic perspective. And if we can find a reason to go there why not use it. >So here is the proposal. >3) Individual crew members must have a reasonable chance to get rotated >back to earth and/or quit the mission at various intervals. i.e. , there >must be regular "shuttle bus" service, and this must be cost effective How long would people work around TC? At least 10 years would be reasonable. This means that you would be about 30 years away from Earth. Would you like that? I certainly wouldn't. Also this would imply that each person would cost twice as much as staying at TC. (Note that staying there does not mean suicide). >4) "Shuttle busses" can assume loaded accel and decel tracks, or >conversly they can assume functioning maser transmitters in both systems. Is it feasable that such a system can be build on TC in a short (10 year) period? My guess is that the "few" people that went with the Asimov have a lot of other things to do. >I think the next vote shold be on engine type, but that should probably >wait until we can get the Newsletter back up and running. How can we possibly vote on such a matter if we don't even know what amounts of energy and power or involved per design. The only propulsion system 'I' know exact numbers of is just the take-all-fuel-with-you method. I have done relativistic calculations for this method involving all kinds of fuel (chemical to antimatter). These calculations have not yet been send to LIT, since its are rather long derivation. I will make it available if any one likes to see it. Another possibility is that I just show one the final formula's. But even these are not pleasant to look at. My results about fuel:ship ratio seem to agree with those of Steve VanDevender, only he had not numbers about energy and power. Timothy From popserver Mon Nov 6 01:43:51 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1137" "Sun" "5" "November" "1995" "20:40:54" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "26" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA10062; Sun, 5 Nov 95 17:41:44 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id UAA06041; Sun, 5 Nov 1995 20:40:54 -0500 Message-Id: <951105204049_13706207@emout05.mail.aol.com> X-UIDL: 815622186.019 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, hedmarc@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Mini SD-newsletter Date: Sun, 5 Nov 1995 20:40:54 -0500 To : Timothy ReplyTo: Kelly >Ok, how do you get the decel fuel in the Target star systems decel track, and >at an acceptable speed? To get their befor the ship it would have to be >going at relativistic speeds. But if its going that fast, the ship couldn't >catch its decel fuel. i.e. the ship would slow down, but the fuel wouldn't. >> Another way to get it at the target before the Asimov is >> to send it there before the Asimov is started. What I >> mean is that the slowest fuel-packets will be send >> from Earth many years before the Asimov starts moving >> to TC. ---- Of course there is a minimum >> limit speed for the slowest and first package: The slower >> it moves the earlier it has to be send to TC. If we would >> need real slow packets we would need sending them now >> already. Thats the problem. 1) if the ship needs fuel for .2 C or less, for a Tau Ceti flight it would have to be launched about 60 years before the ship gets there. 2) To do all this precise launch timing decades before the flight leaves would be perfect assurence that the fuel and ship will NOT get together at the proper time. From popserver Mon Nov 6 01:48:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1107" "Sun" "5" "November" "1995" "20:41:24" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "25" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA10116; Sun, 5 Nov 95 17:43:25 PST Received: by emout06.mail.aol.com (8.6.12/8.6.12) id UAA27127; Sun, 5 Nov 1995 20:41:24 -0500 Message-Id: <951105204120_13706644@emout06.mail.aol.com> X-UIDL: 815622526.000 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Mini SD-newsletter Date: Sun, 5 Nov 1995 20:41:24 -0500 >Even if >you cut off the fuel supply at a speed of .1 C (and how can you slow down >from this insane speed without fuel?) >> OK you wonder how to decelerate even further? Easy, >> don't burn all the fuel from the packets as soon as you get >> a hold of them. OK, the ship gets a bit heavier and would >> be a bit more difficult to decelerate, but every system >> has some advantages. That extra bit of weight/fuel >> should be just enough to decelerate from 0.1c to 0.0c. Thats a very good point! If the fuel stream can get the ship down to a speed that it can decelerate down from with stored fuel, it could be done. SCheduling the flight precisly enough to intercept the fuel is a problem (assuming you can launch the fuel the precisely!) but again that would only be a problem for a first flight if you bring along equip to build fuel launchers in system. However gven the target of Tau Ceti, and the practical time limits of 20 years were talking about fuel at over 1/2 light speed. Oh, I suppose we'ld get some decel force out of the drage we'ld get from picking up the slower fuel. Kelly From popserver Mon Nov 6 01:53:58 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["612" "Sun" "5" "November" "1995" "19:51:14" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "19" "Re: Mini SD-newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA10606; Sun, 5 Nov 95 17:52:20 PST Received: by maroon.tc.umn.edu; Sun, 5 Nov 95 19:51:14 -0600 In-Reply-To: <951105204049_13706207@emout05.mail.aol.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 815622829.001 From: Kevin C Houston To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, hedmarc@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Mini SD-newsletter Date: Sun, 5 Nov 1995 19:51:14 -0600 (CST) On Sun, 5 Nov 1995 KellySt@aol.com wrote: > To : Timothy > > > Thats the problem. 1) if the ship needs fuel for .2 C or less, for a Tau > Ceti flight it would have to be launched about 60 years before the ship gets > there. 2) To do all this precise launch timing decades before the flight > leaves would be perfect assurence that the fuel and ship will NOT get > together at the proper time. > Agreed, The timing difficulties alone would make this a problematic approach. Granted it may be physically possible, but that does not mean that it's practical. I say "nice try guys", but no cigar. Kevin From popserver Mon Nov 6 16:59:58 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6783" "Mon" "6" "November" "1995" "13:01:56" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "146" "Engineering Oldies letter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA02591; Mon, 6 Nov 95 04:02:26 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA01975 (5.67b/IDA-1.5 for ); Mon, 6 Nov 1995 13:01:34 +0100 Message-Id: <199511061201.AA01975@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815677179.004 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Engineering Oldies letter Date: Mon, 06 Nov 1995 13:01:56 +0100 Just after the last official newsletter was send, I mailed these message to LIT. Because of this some messages seem to be very old, but their content still applies, so I send them here: To : All >From : Timothy Subject : Overheating I have serious doubts if we can cool the engine of the Asimov or the beaming-apparatus in solar orbit. If only a small fraction of the needed power is transferred to heat, things will melt or be blown away very fast. Since the power needed will be very big (1E18 Watt) only small portions (1E12=0.001%) that are not efficiently used can give real trouble. I don't think efficiecies of more than 99 percent are feasable. So, does any of you have a solution to this overheating problem? My guess is that cooling water would not work. And if the engine is on the Asimov the trouble would even be bigger, since space isn't much of a cooling fluid. To : Kevin >From : Timothy Re : Flat floors, curved walls >Yes they do flex, or else I missed something major. consider the hab >train while the ship is under acceleration let us designate the floor/ceiling >familiar trip, you notice that it is the distance between cabs at the top >of the cars that is shorter, and the distance near the floor that is longer. So far OK. >unless you want people to suit up every time they pass between cars, you >are going to have to have a flexible conduit for them to walk through. Nope, the junctions would indeed be curved but would be stationary. The shorter part would always be at the inside of the ring. Now only the tubes would need to turn. The connection between the junction and the tube would just be some turnable connection like a wheel that can rotate around an axis. To : Kevin Houston >From : Timothy van der Linden Re : MARS Design. >I agree that the momentum is large, but there will be many transmitters, >so each individual one may not be affected so much. However, if this >turns out not to be the case, the effect can be totally negated by a >but no trqansmitter should have to do this very often. Of course you >would have to double the amount of transmitters, because half of them >would be occulted by the Sun at any one time. Let us take 100 "cubes" weighing approx. 10 ton each: Total weigh 1E6 kg. Since the total weight of the cubes is much less than the MARS-design (M=2.5E9) their end-velocity would be greater than that of the Asimov. So their total weight should be at least 10 to 100 times bigger than that of the MARS-design if we don't want the cubes to leave our solar system. According to my calculations each one of the 100 "cubes" would get an acceleration of about 8000 m/s^2 if they wanted to power the Asimov. Since this is quite much the "cube" would be blown out of orbit before it could make one orbit around the Sun, so you add and subtract method would not work. Another problem will be that the collectors on the cubes will be blown away by the Sun's photons. You may think that photons don't have that much momentum. But I assure you that the amount of photons that have to be collected is big enough to do that. In fact you can compare a cube-collectors with a large mirror reflecting Sun's photons to the Asimov. This means that the collectors get twice the momentum of the the Asimov. My idea would be to build mirrors or solar panels with a maser on the moon or Mars. The only disadvantage is that the mirrors or panels should be larger but the advantage is that they would not need to be launched. To get some feel about the size we are talking about: The mean power we need would be at least 4E17 Joule/second. That would mean a collector with the size of 4.4E13 square metres in the same orbit as Mercury or one that is 20 times bigger on Mars. The problem is that Mars is not big enough! Having done thes calculations make me realize that the collectors that are attached to the cubes may weigh much much more than 6 ton and that making the collectors would be more difficult than making the Asimov. I hope I've not confused you by the numbers, but I really think they are right. (The value of 4E17 is an approximation. I first calculated the total kinetic energy of the Asimov with speed 0.74c and then devided that by the time it took to accelerate the Asimov to that speed.) As far as I can see it, direct solar power would not be feasable. To : Kevin >From : Timothy Re : Electrons and shielding. >We can't carry a UV laser with us, because it would never be the right >wavelength (due to doppler shifting) so it would have to be a Sol based >system. but if we are going to use a UV laser (to clear our path) then we >might as well use that to power our spacecraft, radically altering our >design. anyone know how to convert uv photons to electicity with the >nearly 90% efficeincy of a microwave converter? (me niether :( Clearing the way for the Asimov with a Sol based system would mean that all that is in between would be ionized as well. That would mean a lot of extra energy. I'm sure that in 2040 we have variable lasers in the UV-range. We now already have them in the visible range. >The only other way i know to ionize an atom, is to hit it with a positron. >not go where we wanted. I suppose we could emit some particle that would >be nuetral, but would then decay into positrons, but such a particle >would violate charge conservation (any ideas?) Such a particle would be a free anti-neutron it has a decay time of 10.6 minutes and its reaction products are a positron, an anti-electron and a anti-neutrino. But unfortunately anti-neutrons would cost too much energy to make for this purpose. >given all this, I think a simple erosion plate on the front of the ship >might be the best answer. something about 2000 meters in rad, and about >20 meters (just a guess) thick. shaped into a blunt cone (we do want to >travel at c for part of this trip). the incoming H,He,etc would hit >this, gouging pits and becomming imbeded. the overall force of this >material striking us would be the same no matter if we push it out of the >way with magnetic fields or let it impact a physical barrier. I guess that is like what I was saying all along. >Oh man, this gets more expensive (energy wise) by the minute. >Please, Please, somebody flame me and tell me i forgot something that >will let us ionize everything ahead of us and go back to using mag fields >for shields. I can't think of a single thing. we might have to limit >our top speed to some high fraction of c, won't add that much more to the >trip. let's say for arguments sake, that we limit ourselves to .95 C. I really think a variable laser onboard the Asimov could do the trick. From popserver Mon Nov 6 17:00:01 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["884" "Mon" "6" "November" "1995" "13:02:10" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "23" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA02590; Mon, 6 Nov 95 04:02:24 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA02048 (5.67b/IDA-1.5 for ); Mon, 6 Nov 1995 13:02:04 +0100 Message-Id: <199511061202.AA02048@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815677179.005 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Engineering Newsletter Date: Mon, 06 Nov 1995 13:02:10 +0100 OK, my theory strands on practical difficulties, so we are back to zero. So I quote Kevin (Newsletter 00:29 11-04-95) >Either beam the power, or >figure out how to use the Interstellar Medium (ISM) as a brake. I say >that beaming the power is the quickest easiest solution. Beaming the power would still mean a timing problem of about 10 years? And another problem for this method would be that you get a large amount of momentum in the wrong direction (ie. in the direction of TC). Using ISM would be great, but it seems that only VERY BIG scoops could do the trick. I still haven't seen a formula about a scoop field. Kevin you seem to have one, is it possible that I could see that formula? Maybe we should find a nearby star in a nebula, that sure would increase the ISM-density. I'm not sure if there are any nearby nebulae. Does someone know more about that? Timothy From popserver Mon Nov 6 23:52:47 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1646" "Mon" "6" "November" "1995" "17:48:30" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "44" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA12615; Mon, 6 Nov 95 15:49:21 PST Received: by maroon.tc.umn.edu; Mon, 6 Nov 95 17:48:38 -0600 In-Reply-To: <199511061202.AA02048@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 815701951.002 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Mon, 6 Nov 1995 17:48:30 -0600 (CST) On Mon, 6 Nov 1995, Timothy van der Linden wrote: > > OK, my theory strands on practical difficulties, so we are back to zero. > > So I quote Kevin (Newsletter 00:29 11-04-95) > > >Either beam the power, or > >figure out how to use the Interstellar Medium (ISM) as a brake. I say > >that beaming the power is the quickest easiest solution. > > Beaming the power would still mean a timing problem of about 10 years? And > another problem for this method would be that you get a large amount of > momentum in the wrong direction (ie. in the direction of TC). 1) about the timing problem. Since "Asimov" and the beam are traveling in the same direction, the beam starts at the same time that the "Asimov" does. Also, the beam only needs to be on for about 1.5 years due to relativistic effects 2) this isn't a maser sail, the momentum imparted by the beam itself is negligible compared to the momentum generated by the engine exhaust. and since the engine exhaust can be directed either foreward or backward, this is not a problem > > Using ISM would be great, but it seems that only VERY BIG scoops could do > the trick. I still haven't seen a formula about a scoop field. Kevin you > seem to have one, is it possible that I could see that formula? > I have posted it several times, i will do so again soon. i can't seem to locate it right now, but it's not hard to derivate > Maybe we should find a nearby star in a nebula, that sure would increase the > ISM-density. I'm not sure if there are any nearby nebulae. Does someone know > more about that? > then how do we get from the nebula to the target system? Kevin From popserver Tue Nov 7 18:54:05 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2618" "Tue" "7" "November" "1995" "12:11:57" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "61" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA16096; Tue, 7 Nov 95 03:11:59 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA02078 (5.67b/IDA-1.5 for ); Tue, 7 Nov 1995 12:11:44 +0100 Message-Id: <199511071111.AA02078@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 815770421.002 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Tue, 07 Nov 1995 12:11:57 +0100 ReplyTo: Kevin >1) about the timing problem. Since "Asimov" and the beam are traveling >in the same direction, the beam starts at the same time that the "Asimov" >does. Also, the beam only needs to be on for about 1.5 years due to >relativistic effects The Asimov will take at least 1 year to accelerate.So the beam won't start at the same time but at least 1 year later. Also the beam of photons travels with the speed of light so it has be beamed another 5 years later, so that it does not catch up with the Asimov prematurely. Besides that problem, the beam then still has to be aimed exactly at the place where the Asimov will be after about 15 years, and it should be there at that time and not a month later. Maybe I haven't used the correct To me this still seems to be a timing problem. If I'm wrong, tell me where. >2) this isn't a maser sail, the momentum imparted by the beam itself is >negligible compared to the momentum generated by the engine exhaust. and >since the engine exhaust can be directed either foreward or backward, >this is not a problem What matters is the energy:momentum ratio of the beamed power. For the photons in the beam that ratio is: E:p = c:1 where c=3E8 For the Asimov moving at 0.7 c that ratio is: E:p = 0.4c:1 The beam needs to have about 1/0.4=2.5 times less momentum than the Asimov, but that is still a lot, so I can't agree with you that the momentum of the beam is neglectable. Using a particle beam would make the problem worse because you would get the same energy:momentum ratio as the ship. Also a particle beam would mean that the amount of received particles increases as the Asimov slows down. >> Using ISM would be great, but it seems that only VERY BIG scoops could do >> the trick. I still haven't seen a formula about a scoop field. Kevin you >> seem to have one, is it possible that I could see that formula? >> >I have posted it several times, i will do so again soon. i can't seem to >locate it right now, but it's not hard to derivate OK, I look forward to it. (I haven't seen it in any newsletter for at least the last 4 months and don't know how I should derive it.) >> Maybe we should find a nearby star in a nebula, that sure would increase the >> ISM-density. I'm not sure if there are any nearby nebulae. Does someone know >> more about that? >> >then how do we get from the nebula to the target system? My hopes were that the star was in or nearby the nebula, so once you are almost to a standstill you are near your destination. Maybe a nebula implies lifeless planets, but I don't know enough about that. Timothy From popserver Thu Nov 9 22:56:16 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["601" "Thu" "9" "November" "1995" "17:51:33" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "18" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail02.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA24270; Thu, 9 Nov 95 14:52:29 PST Received: by mail02.mail.aol.com (8.6.12/8.6.12) id RAA15091; Thu, 9 Nov 1995 17:51:33 -0500 Message-Id: <951109175132_17750050@mail02.mail.aol.com> X-UIDL: 815957739.001 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl Cc: stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Thu, 9 Nov 1995 17:51:33 -0500 > ISM-density. I'm not sure if there are any nearby nebulae. > Does someone know more about that? Sorry this area of the galaxy is unusually empty. No nebula, and the stars are unusually far apart. Cooling the engines? Good point! The fusion engines I was talking about are 99.9+% efficent, but at the power levels were talking about we'ld melt the ship. We seem to have talked oiurselves out of all the engine concepts? We can't launch fuel over interstellar distences. The MARS system seems to need impossibly large collector arrays, and eiather system would cook the ship. bummer. Kelly From popserver Fri Nov 10 19:52:04 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6753" "Fri" "10" "November" "1995" "10:15:17" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "138" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA13547; Fri, 10 Nov 95 08:15:35 PST Received: by maroon.tc.umn.edu; Fri, 10 Nov 95 10:15:19 -0600 In-Reply-To: <199511071111.AA02078@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 816033034.034 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Fri, 10 Nov 1995 10:15:17 -0600 (CST) On Tue, 7 Nov 1995, Timothy van der Linden wrote: > ReplyTo: Kevin > > >1) about the timing problem. Since "Asimov" and the beam are traveling > >in the same direction, the beam starts at the same time that the "Asimov" > >does. Also, the beam only needs to be on for about 1.5 years due to > >relativistic effects > > The Asimov will take at least 1 year to accelerate.So the beam won't start > at the same time but at least 1 year later. Also the beam of photons travels > with the speed of light so it has be beamed another 5 years later, so that > it does not catch up with the Asimov prematurely. > Besides that problem, the beam then still has to be aimed exactly at the > place where the Asimov will be after about 15 years, and it should be there > at that time and not a month later. > Maybe I haven't used the correct > To me this still seems to be a timing problem. If I'm wrong, tell me where. Be glad to. First, the "Asimov" will need power from day one, so the beam will be on from day 1. Toward the center of the trip, the "Asimov" will be moving close to C, and will travel with the beam. if you look at the last day of the trip, you see that according to earth's clocks about 13.25 years have elapsed, but since TC is only 12 LY away, that means that the beam of energy left earth only 1.25 years after we did. Also, about "aiming", the maser beam will be a straight line between the two stars, we will follow the beam. there isn't really any "aiming" problem, there _is_ a "jitter" problem ie. how to keep the beam from pointing slightly away from TC and causing the poser to "wink" on and off years later at the "Asimov" > > >2) this isn't a maser sail, the momentum imparted by the beam itself is > >negligible compared to the momentum generated by the engine exhaust. and > >since the engine exhaust can be directed either foreward or backward, > >this is not a problem > > What matters is the energy:momentum ratio of the beamed power. > For the photons in the beam that ratio is: > > E:p = c:1 where c=3E8 > > For the Asimov moving at 0.7 c that ratio is: > > E:p = 0.4c:1 > > The beam needs to have about 1/0.4=2.5 times less momentum than the Asimov, > but that is still a lot, so I can't agree with you that the momentum of the > beam is neglectable. > > Using a particle beam would make the problem worse because you would get the > same energy:momentum ratio as the ship. Also a particle beam would mean that > the amount of received particles increases as the Asimov slows down. no, I am talking about the momentum of the photons as opposed to the momentum of the ions the "Asimov" will eject as exhaust. Those will be Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how much energy you can invest) C at these speeds, a small mass flow is sufficient to slow us down (or speed us up depending on which phase of the mission we are in) at a constant 1 G. Now, about the energy of photons/area of collectors/mass of collectors problem. Any of these so called problems can be solved by the same solution. namely increasing the number of collectors. Timothy, you were talking about the problems associated with 100 collectors/transmitters beaming power to the "Asimov" I agree with you, 100 transmitters is way too small. I was initially planning on 720 (one every half degree) transmitters, but there is no reason (aside from cost) that we can't have 7200, or 7.2 E 18 transmitters (each one sending a few watts of energy and costing ten dollars) increasing the number of transmitters will: reduce the amount of photon thrust that each transmitter is subjected to. reduce the amount of solar array that each trnsmitter must have. reduce the amount of beam jitter (by averaging the errors, they are reduced) reduce the heat load of each transmitter. (the non-Sol side of the solar panels will make an excellent heat radiator) increase the total cost of the mission (hey, you don't get nothing for free) Heat load on the asimov: I do not understand why people think this is a problem, that must mean that I am not seeing something. so, I will tell you why I think this is a non-issue (or even a benefit) . Heat generation will come from two sources. 1) (and the largest) conversion of microwaves to electricity. This takes place with between 85 - 90 percent efficiency, and for our purposes, 15% heat load (from 1E18 Watts) is still a lot. _BUT_ the conversion would take place on the antenna itself. diodes wired directly onto the metal mesh would do the power converting and the mesh (of special radiator fins if need be) could radiate the heat. we have thousands and thousands of square meters of antenna, it would serve as an exceptional radiator. Also, if we used "memory metal" in the antenna, the heat of conversion could be directed to hold the antenna rigid. _also_ Heat (for living quarters etc) radiates as the square of the size of the "Asimov", there will be little or no radiation coming into the living quarters, but a lot will be leaving. We are going to have to do an energy balance on the heat so we can determine the equilibrium temp of the living quarters. but my guess is that it will be on the chilly side, and so we may want all the heat we can get. 2) heat will be generated in the coils for the linear accelerator core. This can be minimized by using superconducting electromagnets, but there will always be inefficiencies. Assuming that we can get 99% efficiency out of superconductors, (not unreasonable) that means we will have to deal with 1 E16 watts of thermal energy. _BUT_ This will be spread out over the length of the entire core. also, we are going to have to raise the temp of the reaction mass from near Zero (kelvin) in the case of Hydrogen, to something approaching room temp (depends on which superconductors you use, we could use the old ceramic style ones, and limit ourselves to ~ 200 K I know a lot of people who'ld like to scrap their old ceramic superconductors for the newer room-temp ones, maybe we can save a buck or two and buy those up ;p ) (the reaction mass would then also serve to cool the superconductors) This heat, rather than the anntenna heat would probably be best suited to heating the living quarters. Surprisingly enough, the exhaust itself will not be all that hot. There is no chemical or fusion reaction going on in the exhaust, so the only heat is the heat we allow to go in from the coils on the magnets. whatever heat is left over, can easily be pumped (using hot water) to the outside of the ship. radiator fins along the length of the ship would radiate the heat into space. Kevin From popserver Fri Nov 10 19:52:08 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["976" "Fri" "10" "November" "1995" "10:24:01" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "27" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA13995; Fri, 10 Nov 95 08:24:15 PST Received: by maroon.tc.umn.edu; Fri, 10 Nov 95 10:24:02 -0600 Reply-To: Kevin C Houston In-Reply-To: <951109175132_17750050@mail02.mail.aol.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII X-UIDL: 816033034.036 From: Kevin C Houston Sender: Kevin C Houston To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Fri, 10 Nov 1995 10:24:01 -0600 (CST) To: all Re: LIT I just got a meassage from David saying that he is working hard on restoring the newsletters. I don't know if he sent the same message to everyone else or not, so i thought I'd pass this on. BTW, has anyone kept all copies of the Mini-LIT newsletter to put in the archives? I must admit I have not. And, Brian has written me saying that he no longer wants to get seven messages a day. I wasn't sure how long the current situation would continue, so I wasn't sure how to respond to this message. So what about it brian? You want us to delete your name from the cc: field, or do you want to hang around until the newsletter gets restored? please reply to everyone, so that we all know your wishes. Thanks. Kevin PS anyone else who wants to get deleted needs to respond here also. I am not the "keeper" of the newsletter, I am only one person talking to my friends over the internet. like all internet activities, this is a true anarchy. From popserver Fri Nov 10 19:52:23 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["627" "Fri" "10" "November" "1995" "11:57:29" "-0500" "Brian Van Straalen" "bpvanstr@yoho.uwaterloo.ca" nil "15" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from yoho.uwaterloo.ca by efn.efn.org (4.1/smail2.5/05-07-92) id AA15955; Fri, 10 Nov 95 08:57:04 PST Received: (from bpvanstr@localhost) by yoho.uwaterloo.ca (8.6.12/8.6.12UW) id LAA20473; Fri, 10 Nov 1995 11:57:29 -0500 Message-Id: <199511101657.LAA20473@yoho.uwaterloo.ca> In-Reply-To: from "Kevin C Houston" at Nov 10, 95 10:24:01 am X-Mailer: ELM [version 2.4 PL24] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 627 X-UIDL: 816033034.044 From: Brian Van Straalen To: hous0042@maroon.tc.umn.edu Cc: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Fri, 10 Nov 1995 11:57:29 -0500 (EST) > > And, Brian has written me saying that he no longer wants to get seven > messages a day. I wasn't sure how long the current situation would > continue, so I wasn't sure how to respond to this message. > > So what about it brian? You want us to delete your name from the cc: > field, or do you want to hang around until the newsletter gets restored? Seeing as there doesn't seem to be a time frame for re-establishing a newsletter format, I opt to be removed from the cc. field. It would be nice to be re-established into the list when a newsletter does get generated that I can be re-established. thanks, Brian From popserver Fri Nov 10 23:03:19 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4410" "Fri" "10" "November" "1995" "23:57:58" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "110" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA09458; Fri, 10 Nov 95 14:57:42 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA24464 (5.67b/IDA-1.5 for ); Fri, 10 Nov 1995 23:57:52 +0100 Message-Id: <199511102257.AA24464@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 816044553.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Fri, 10 Nov 1995 23:57:58 +0100 ReplyTo : Kelly ReplyFrom: Timothy >We seem to have talked oiurselves out of all the engine concepts? We can't >launch fuel over interstellar distences. The MARS system seems to need >impossibly large collector arrays, and eiather system would cook the ship. > >bummer. Cheer up Kelly, we will find a way, we can always make a multi-generation ship, I guess. Subject : Photon energy ReplyTo : Kevin ReplyFrom: Timothy OK, I agree with you about the aiming and timing 'problem' I wrote you about. But I think I found another problem, so read on. >> What matters is the energy:momentum ratio of the beamed power. >> For the photons in the beam that ratio is: >> >> E:p = c:1 where c=3E8 >> >> For the Asimov moving at 0.7 c that ratio is: >> >> E:p = 0.4c:1 >> >> The beam needs to have about 1/0.4=2.5 times less momentum than the Asimov, >> but that is still a lot, so I can't agree with you that the momentum of the >> beam is neglectable. WARNING! I made a mistake here, I forgot that the momentum of the Asimov increased while it was receiving photons. So the best thing to do is forget the above. >no, I am talking about the momentum of the photons as opposed to the >momentum of the ions the "Asimov" will eject as exhaust. Those will be >Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how >much energy you can invest) C at these speeds, a small mass flow is >sufficient to slow us down (or speed us up depending on which phase of >the mission we are in) at a constant 1 G. This was clear to me, but rethinking this made me realize that your method can't work. Because adding momentum to the Asimov will only make it move faster. Transforming it to reverse momentum would surely break one of the basic physic laws. In formulas: - You shoot some photons at the Asimov, that will give an energy Up=p*c where p is the momentum of the photon. - To accelerate a mass M to speed v to decelerate the Asimov, we need an amount of energy Uk=M*c^2*(gamma-1). - We use all the energy of the received photons for that acceleration, so Up=Uk --> p*c=M*c^2(gamma-1) --> p=M*c*(gamma-1) - Thus to accellerate a mass M to speed v we need to receive photons which will add us a momentum of p=M*c*(gamma-1). - But of course we can subtract some momentum that we created by shooting that mass M away. That momentum equals to p=gamma*M*v. - Now the problem arises because by receiving photons we gain more momentum that we loose by shooting that mass M away. In physics: gamma*M*v is always less than M*c*(gamma-1) Subject : Solar array ReplyTo : Kevin ReplyFrom: Timothy >increasing the number of transmitters will: >reduce the amount of photon thrust that each transmitter is subjected to. >reduce the amount of solar array that each trnsmitter must have. >reduce the amount of beam jitter (by averaging the errors, they are reduced) >reduce the heat load of each transmitter. (the non-Sol side of the solar > panels will make an excellent heat radiator) >increase the total cost of the mission (hey, you don't get nothing for free) But it won't reduce the total solar array, which is really big: Total Solar Power : 4E26 Watts Area of a globe with radius 1E9 metres : 7.9E17 square metres -> Solar power per square metre : 5E8 Watt Mean amount of power needed by the Asimov : 1E18 Watt -> Size of solar array : 1E18/5E8 = 2E9 square metres = disc with radius 2.5E4 metres. Remember 1E9 metres is quite near Sol. You wouldn't like to be there in your space suit, because 5E8 Joules would be added to your body temperature every second. Subject : Overheating ReplyTo : Kevin ReplyFrom: Timothy The main solution for the energy-leak in your letter was 'radiate it away'. You say the antenna mesh can radiate it away. You assume the leaking-energy can be radiated away before it can do any damage. Let us assume that the leaking-energy is ordinary Ohmic resistance and thus emerges as heat in the mesh. I think that before it can radiate away the mesh is molten or has disappeared altogether. So my problem is wheter one can radiate it away fast enough. And if you seem to be able to guide the energy so well, why not use it. The amount of energy leaving the crew quarters should not be that much, It will probably some kind of thermos flask. From popserver Sun Nov 12 06:55:16 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2320" "Sat" "11" "November" "1995" "22:12:05" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "51" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail02.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA13959; Sat, 11 Nov 95 19:12:46 PST Received: by mail02.mail.aol.com (8.6.12/8.6.12) id WAA18549; Sat, 11 Nov 1995 22:12:05 -0500 Message-Id: <951111221204_104196661@mail02.mail.aol.com> X-UIDL: 816159261.001 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl Cc: stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Sat, 11 Nov 1995 22:12:05 -0500 >> Heat load on the asimov: >> Heat generation will come from two sources. >> 1) (and the largest) conversion of microwaves to >> electricity. This takes place with between 85 - 90 >> percent efficiency, and for our purposes, 15% >> heat load (from 1E18 Watts) is still a lot. >> _BUT_ >> the conversion would take place on the antenna itself. >> diodes wired directly onto the metal mesh would do the >> power converting and the mesh (of special radiator fins >> if need be) could radiate the heat. we have thousands and >> thousands of square meters of antenna, it would serve as >> an exceptional radiator. ---- I'll buy this part. With the hundreds to thousands of square kilometers of mesh you've been taling about you have a lot of radiator space. Asuming you can radiate the energy away fast enough to keep everything down to operating temperature. If you want supper conductors this could be dicy. They like cold temps and radiators like it very hot. >> 2) heat will be generated in the coils for the linear >> accelerator core. This can be minimized by using >> superconducting electromagnets, but there will always be >> inefficiencies. Assuming that we can get 99% efficiency >> out of superconductors, (not unreasonable) that means we >> will have to deal with 1 E16 watts of thermal energy. >> _BUT_ >> This will be spread out over the length of the entire core. >> also, we are going to have to raise the temp of the >> reaction mass from near Zero (kelvin) in the case of >> Hydrogen, to something approaching room temp >> -- (the reaction mass would then also serve to cool the >> superconductors) >> This heat, rather than the anntenna heat would probably be >> best suited to heating the living quarters. Kevin, the heat your talking about is enough to provide for all the electricity for a few thousand cities the size of Chicago! Thats the kind of power that keeps all those cities outside air temp a few degrees above country temps. You can't just brush that off by saying the engine will be a few klicks long and were can pump a lot of heat into the reaction mass. (Frankly I doubt the reaction mass can absorb that kind of heat load.) This is a lot of power, and we need to know what were going to do with it or the ship will cook itself alive. Kelly From popserver Sun Nov 12 06:55:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2171" "Sat" "11" "November" "1995" "22:12:41" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "52" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA14016; Sat, 11 Nov 95 19:14:20 PST Received: by mail04.mail.aol.com (8.6.12/8.6.12) id WAA28603; Sat, 11 Nov 1995 22:12:41 -0500 Message-Id: <951111221240_104196975@mail04.mail.aol.com> X-UIDL: 816159261.003 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, bpvanstr@yoho.uwaterloo.ca Subject: Re: Engineering Newsletter Date: Sat, 11 Nov 1995 22:12:41 -0500 >> Subject : Photon energy >> ReplyTo : Kevin >> ReplyFrom: Timothy >no, I am talking about the momentum of the photons as opposed to the >momentum of the ions the "Asimov" will eject as exhaust. Those will be >Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how >much energy you can invest) C at these speeds, a small mass flow is >sufficient to slow us down (or speed us up depending on which phase of >the mission we are in) at a constant 1 G. >> This was clear to me, but rethinking this made me >> realize that your method can't work. Because adding >> momentum to the Asimov will only make it move >> faster. Transforming it to reverse momentum would >> surely break one of the basic physic laws. No Tim. The momentum of the microwave is simply added load on the antena support structure (which is an extreamly unlikely structure) assuming it can take the load the power (electric) them feeds the engines which use it to produce forward or backward thrust. No violation of conservation of momentum. As long as the engine is powerful enough (and antenna strong enough) to overcome the thrust load of the photon sail effect of the big antenna. Every thing is fine. >> Subject : Solar array >> ReplyTo : Kevin >> ReplyFrom: Timothy >> But it won't reduce the total solar array, which is really big: >> Total Solar Power : 4E26 Watts >> Area of a globe with radius 1E9 metres : 7.9E17 square >> metres >> -> Solar power per square metre : 5E8 Watt >> Mean amount of power needed by the Asimov : 1E18 Watt >> -> Size of solar array : 1E18/5E8 = 2E9 square metres >> = disc with radius 2.5E4 metres. >> Remember 1E9 metres is quite near Sol. You wouldn't like >> to be there in your space suit, because 5E8 Joules would >> be added to your body temperature every second. Are you talking about a 5 kilometer disk a million kilometers from the suns surface? Does this not strike you as a servicing problem? Solar Power Density out here by earth is 1.35 KW/m^2 not the 5E8 Watt/m^2, but the equipment will be a lot more likely to keep working. Kelly Starks From popserver Mon Nov 13 05:58:00 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6302" "Mon" "13" "November" "1995" "01:18:59" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "138" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA26965; Sun, 12 Nov 95 16:18:26 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA07137 (5.67b/IDA-1.5 for ); Mon, 13 Nov 1995 01:18:54 +0100 Message-Id: <199511130018.AA07137@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 816242187.022 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Mon, 13 Nov 1995 01:18:59 +0100 ReplyFrom: Timothy Subject : LIT >BTW, has anyone kept all copies of the Mini-LIT newsletter to put in the >archives? I must admit I have not. I did, if some one needs it, ask... ReplyTo : Kelly ReplyFrom: Timothy Subject : Drawings About the drawing: where did you plan the shielding. And does it ride along with the hab ring, thus at 1 g? I had in mind that we made a shielding tube in which the hab-sections rotated. So then the shielding would not move and would not create an extra outward stress-factor. >>> What program did you use. > >RayDream designer 3. They were selling it for $100 bucks in MacWarehouse and >such a while back. So I picked it up. Won't run on the old Macintosh Plus I >have at home, but it runs like a bat out of hell on the new power Mac I have >at the office. I figured it would encourage me to get a new computer faster. If any one else likes doing raytraces, you can get PovRay or Radiance for FREE on the internet. I use PovRay and can make the same kinds of drawings. These are well know raytracers and work great. These programs are available for different platforms. (Tip: jpeg images would be about 4 times smaller, so would mean a less bytes with almost the same image quality) >Far larger than that. A multi generation ship would be technically far >harder then a fast relatavistic ship. To have half a chance it would need to >be compleatly self contained and self sufficent. With enough fuel and >resources for decades to centuries. Say a couple times the size of Manhattan >and with a population of hundreds of thousands of people. All that assuming >a big jump in technology to support it all with a crew that small. Indeed the ship itself would probably bigger than a rel. ship but, I don't think that energy will be a problem. The amounts of energy needed for a rel. ship are far more. It's quite easy to calculate the amount of energy that is needed for a self sustaining system. On Earth the energy income is 1400 Watts per square metre. With that energy all plants and animals seems to do well. Now the question is how much space per person is needed. Say 10000 square metres? That makes 4.4E14 Watts per person per year. The rel. ship engine would use 1000 times more per second. So now the only problem is to build that large ship. Material from astroids would probably be the main source. At the outer part of our solar system there seem to be billions of them in all the sizes you want. Making a self sufficient system should not be that hard with enough energy available. ReplyFrom: Timothy ReplyTo : Kevin and Kelly >>> _BUT_ >>> the conversion would take place on the antenna itself. >>> diodes wired directly onto the metal mesh would do the >>> power converting and the mesh (of special radiator fins >>> if need be) could radiate the heat. we have thousands and >>> thousands of square meters of antenna, it would serve as >>> an exceptional radiator. ---- > >I'll buy this part. With the hundreds to thousands of square kilometers of >mesh you've been taling about you have a lot of radiator space. Asuming you >can radiate the energy away fast enough to keep everything down to operating >temperature. If you want supper conductors this could be dicy. They like >cold temps and radiators like it very hot. I don't buy that part: Take 1 square kilometre or 1E6 square metres, that means 1E18/1E6=1E12 Watt per square metre. Take 10% of that and you get 1E11 Watts of lost energy per square metre. That sure would melt anything away. Even with thousands of square kilometres it is still too much. >Kevin, the heat your talking about is enough to provide for all the >electricity for a few thousand cities the size of Chicago! Thats the kind of >power that keeps all those cities outside air temp a few degrees above >country temps. You can't just brush that off by saying the engine will be a >few klicks long and were can pump a lot of heat into the reaction mass. > (Frankly I doubt the reaction mass can absorb that kind of heat load.) This >is a lot of power, and we need to know what were going to do with it or the >ship will cook itself alive. I agree. Also super conducting wires don't like very heavy currents. Subject : Photon energy ReplyTo : Kelly ReplyFrom: Timothy >>no, I am talking about the momentum of the photons as opposed to the >>momentum of the ions the "Asimov" will eject as exhaust. Those will be >>Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how >>much energy you can invest) C at these speeds, a small mass flow is >>sufficient to slow us down (or speed us up depending on which phase of >>the mission we are in) at a constant 1 G. > >>> This was clear to me, but rethinking this made me >>> realize that your method can't work. Because adding >>> momentum to the Asimov will only make it move >>> faster. Transforming it to reverse momentum would >>> surely break one of the basic physic laws. > >No Tim. The momentum of the microwave is simply added load on the antena >support structure (which is an extreamly unlikely structure) assuming it can >take the load the power (electric) them feeds the engines which use it to >produce forward or backward thrust. No violation of conservation of >momentum. As long as the engine is powerful enough (and antenna strong >enough) to overcome the thrust load of the photon sail effect of the big >antenna. Every thing is fine. No, that's not what I meant. I think that the energy that is gained by receiving the photons is not enough to overcome the velocity gain that you get by receiving these photons. So a powerful engine doesn't work because there isn't enough fuel. Subject: Solar array ReplyTo : Kelly ReplyFrom: Timothy >Are you talking about a 5 kilometer disk a million kilometers from the suns >surface? Does this not strike you as a servicing problem? In fact I was talking about a 50 kilometre disc... >Solar Power Density out here by earth is 1.35 KW/m^2 not the 5E8 Watt/m^2, >but the equipment will be a lot more likely to keep working. I agree completely, but having it so near Earth means a much bigger array. 5E8/1.35E3=3.7E5 times bigger to be exact. That is about 1.5 times the surface of the Earth!!! That seems to be an even bigger problem :) From popserver Mon Nov 13 18:03:10 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7269" "Mon" "13" "November" "1995" "04:38:45" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "177" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA21414; Mon, 13 Nov 95 02:38:39 PST Received: by maroon.tc.umn.edu; Mon, 13 Nov 95 04:38:45 -0600 Reply-To: Kevin C Houston In-Reply-To: <199511102257.AA24464@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII X-UIDL: 816285714.005 From: Kevin C Houston Sender: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Mon, 13 Nov 1995 04:38:45 -0600 (CST) On Fri, 10 Nov 1995, Timothy van der Linden wrote: > ReplyTo : Kelly > ReplyFrom: Timothy > > >We seem to have talked oiurselves out of all the engine concepts? We can't > >launch fuel over interstellar distences. The MARS system seems to need > >impossibly large collector arrays, and eiather system would cook the ship. > > > >bummer. > > Cheer up Kelly, we will find a way, we can always make a multi-generation > ship, I guess. Subject : Photon energy ReplyTo : Timothy ReplyFrom: Kevin > > OK, I agree with you about the aiming and timing 'problem' I wrote you > about. But I think I found another problem, so read on. > > >> What matters is the energy:momentum ratio of the beamed power. > >> For the photons in the beam that ratio is: > >> > >> E:p = c:1 where c=3E8 > >> > >> For the Asimov moving at 0.7 c that ratio is: > >> > >> E:p = 0.4c:1 > >> > >> The beam needs to have about 1/0.4=2.5 times less momentum than the Asimov, > >> but that is still a lot, so I can't agree with you that the momentum of the > >> beam is neglectable. > > WARNING! > I made a mistake here, I forgot that the momentum of the Asimov increased > while it was receiving photons. So the best thing to do is forget the above. > That's good, because i didn't understand it anyway. > >no, I am talking about the momentum of the photons as opposed to the > >momentum of the ions the "Asimov" will eject as exhaust. Those will be > >Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how > >much energy you can invest) C at these speeds, a small mass flow is > >sufficient to slow us down (or speed us up depending on which phase of > >the mission we are in) at a constant 1 G. > > This was clear to me, but rethinking this made me realize that your method > can't work. Because adding momentum to the Asimov will only make it move > faster. Transforming it to reverse momentum would surely break one of the > basic physic laws. > Huh? We won't be "subtracting" momentum, We'll just be adding it in the direction opposite to our direction of travel... thus we slow down and no physical laws get broken in the process. That's why a linear accelerator is better than a sail, you can aim your exhaust out of either end. > In formulas: > > - You shoot some photons at the Asimov, that will give an energy Up=p*c > where p is the momentum of the photon. > - To accelerate a mass M to speed v to decelerate the Asimov, we need an > amount of energy Uk=M*c^2*(gamma-1). > - We use all the energy of the received photons for that acceleration, > so Up=Uk --> p*c=M*c^2(gamma-1) --> p=M*c*(gamma-1) > - Thus to accellerate a mass M to speed v we need to receive photons which > will add us a momentum of p=M*c*(gamma-1). > - But of course we can subtract some momentum that we created by shooting > that mass M away. That momentum equals to p=gamma*M*v. > - Now the problem arises because by receiving photons we gain more momentum > that we loose by shooting that mass M away. > In physics: gamma*M*v is always less than M*c*(gamma-1) > All these formulas have me confused, let me see if I can work this out using some real (made-up) numbers. assume E=1 E+19 Watts, mass of "Asimov" = 2.5 E+09 Kg, wavelength of beam = 21 cm. I think we both agree that during the accel phase, the momentum from the photons helps us accelerate. But you are saying that the momentum of the photons is more than the momentum of the exhaust stream during the decelleration phase. hmm. let's see... p=E/c therefore p=3.34 E+10 Kg m/s the "Asimov" masses at 2.5 E+09 so if p=m v then v=p/m and v, (the amount of velocity change) = 13.34 m/s so every second that the beam is on us, we get "pushed" toward T.C. at 13.34 m/s faster than we were before. now let's use that energy we absorbed (minus 20% for conversion losses, now E= 8 E+18) to accelerate some amount of material to allow us to slow down. to find out how much material (per second) we must eject, let's use the rocket equation first. the apparent mass Ma (as seen by the crew) of the exhaust is g * M /Ve * c where Ve is .9996 and g is 23.34 (10 m/s^2 for us, and 13.34 m/s^2 to counteract the photonic thrust) so Ma= 194.71 Kg/sec moving at .9996 of c. note that this is only 3.89 Kg out of the tanks so thus the rest mass of the exhaust is 3.89 Kg/sec. Now let's see how much energy it takes to accelerate 3.89 Kg to .9996 of c the energy will equal the kinetic energy of accelerating the mass to the required speed, plus the energy of the "mass increase" E=Ke + Re Ke=1/2 m v^2 = 1/2 *3.89* (.9996*c)^2 = 1.74 E+17 Re= m c^2 = (194.71 - 3.89) * c^2 = 1.71 E+19 total energy required = 1.73 E+19 But we only have 1 E+19 (8 E+18 after conversion losses) what if we slowed down at 5m/s^2 the rocket equation: g is 18.34 (10 m/s^2 for us, and 13.34 m/s^2 to counteract the photonic thrust) so Ma= 153.00 Kg/sec moving at .9996 of c. note that this is only 3.06 Kg out of the tanks so thus the rest mass of the exhaust is 3.06 Kg/sec. Now let's see how much energy it takes to accelerate 3.89 Kg to .9996 of c the energy will equal the kinetic energy of accelerating the mass to the required speed, plus the energy of the "mass increase" E=Ke + Re Ke=1/2 m v^2 = 1/2 *3.06* (.9996*c)^2 = 1.34 E+17 Re= m c^2 = (153.00 - 3.89) * c^2 = 1.34 E+19 Hardly any decrease at all. Okay, Okay, I see your point (finally). so we can speed up, but we can't slow down even using beamed power. unless we use a retro reflecting ring sail, and that seems like such a waste > > Subject : Solar array > ReplyTo : Kevin > ReplyFrom: Timothy > > >increasing the number of transmitters will: > >reduce the amount of photon thrust that each transmitter is subjected to. > >reduce the amount of solar array that each trnsmitter must have. > >reduce the amount of beam jitter (by averaging the errors, they are reduced) > >reduce the heat load of each transmitter. (the non-Sol side of the solar > > panels will make an excellent heat radiator) > >increase the total cost of the mission (hey, you don't get nothing for free) > > But it won't reduce the total solar array, which is really big: > > Total Solar Power : 4E26 Watts Not really all that much more than the power a 2.5 E+09 Kg ship needs to get up to lightspeed in a decent amount of time. I think the ship needs to go on a diet! > Area of a globe with radius 1E9 metres : 7.9E17 square metres > -> Solar power per square metre : 5E8 Watt > > Mean amount of power needed by the Asimov : 1E18 Watt > -> Size of solar array : 1E18/5E8 = 2E9 square metres > = disc with radius 2.5E4 metres. > or 1000 disks with radius of 25 metres (Okay, Okay, a little more than 25 meters, but you get the point.) > Remember 1E9 metres is quite near Sol. You wouldn't like to be there in your > space suit, because 5E8 Joules would be added to your body temperature every > second. No one would be there, the transmitters would be built near earth, and launched into close solar orbit. if one or another fails, you launch another one rather than try and fix it. Kevin From popserver Tue Nov 14 01:11:43 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["6004" "Mon" "13" "November" "1995" "19:14:11" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951113191409_21423872@mail06.mail.aol.com>" "147" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA04697; Mon, 13 Nov 95 16:16:39 PST Received: by mail06.mail.aol.com (8.6.12/8.6.12) id TAA17058; Mon, 13 Nov 1995 19:14:11 -0500 Message-Id: <951113191409_21423872@mail06.mail.aol.com> X-UIDL: 816311356.035 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Engineering Newsletter Date: Mon, 13 Nov 1995 19:14:11 -0500 to: rddesign@wolfenet.com To: KellySt@aol.com >>> Heat load on the asimov: > >> Kelly >> This is way outside of my knowledge but couldn't this heat >> be expelled like exhaust and added to the thrust? Heat is >> just hot particles, isn't it? No such luck. Heat is eiather the thermal vibration of the molecules in an object, or infared radiation (life in a radiative heater). Can't think of how we'ld pump all the heat out of the ship fast enough to keep it cool. ReplyTo : Kelly ReplyFrom: Timothy Subject : Drawings >> About the drawing: where did you plan the shielding. And >> does it ride along with the hab ring, thus at 1 g? >> I had in mind that we made a shielding tube in which the >> hab-sections rotated. So then the shielding would not >> move and would not create an extra outward stress-factor. I was thinking of having the shielding in a fixed U shaped shielding trough that runs around the inside of the outer hull (the open end of the U points inward). If the shielding is made of steel instead of lead, the hab centrafuge tracks can run around on the top edges of the U. (of course the steel would be at least 3 feet thick!) >> (Tip: jpeg images would be about 4 times smaller, so would >> mean a less bytes with almost the same image quality) Now if Rick would get a JPEG viewer. ;) >Far larger than that. A multi generation ship would be technically far >harder then a fast relatavistic ship. To have half a chance it would need to >be compleatly self contained and self sufficent. With enough fuel and >resources for decades to centuries. Say a couple times the size of Manhattan >and with a population of hundreds of thousands of people. All that assuming >a big jump in technology to support it all with a crew that small. >> Indeed the ship itself would probably bigger than a rel. ship but, I don't >> think that energy will be a problem. The amounts of energy needed for a rel. >> ship are far more. ---- 4.4E14 Watts per person per year. The rel. ship >> engine would use 1000 times more per second. Of course instead of a 5 year (ship time) trip, your talking about centuries to thousands of years, and a crew 10-1000 times larger, and a proportianatly larger ship, etc... You might make an energy savings, but it wouldn't be as dramatic as you might expect. >> So now the only problem is to build that large ship. Material >> from astroids --- Making a self sufficient system should >> not be that hard with enough energy available. Building things takes skills, tools, and materials, as well as power. Of course we didn't give the ship tremendous power reserves. ReplyFrom: Timothy ReplyTo : Kevin and Kelly >>> _BUT_ >>> the conversion would take place on the antenna itself. >>> diodes wired directly onto the metal mesh would do the >>> power converting and the mesh (of special radiator fins >>> if need be) could radiate the heat. we have thousands and >>> thousands of square meters of antenna, it would serve as >>> an exceptional radiator. ---- > >I'll buy this part. With the hundreds to thousands of square kilometers of >mesh you've been taling about you have a lot of radiator space. Asuming you >can radiate the energy away fast enough to keep everything down to operating >temperature. If you want supper conductors this could be dicy. They like >cold temps and radiators like it very hot. >> I don't buy that part: Take 1 square kilometre or 1E6 square metres, that >> means 1E18/1E6=1E12 Watt per square metre. Take 10% of that and you get 1E11 >> Watts of lost energy per square metre. That sure would melt anything away. >> Even with thousands of square kilometres it is still too much. Good point. Subject : Photon energy ReplyTo : Kelly ReplyFrom: Timothy >>no, I am talking about the momentum of the photons as opposed to the >>momentum of the ions the "Asimov" will eject as exhaust. Those will be >>Hydrogen ions or maybe Xenon moving at .9996 or (.99996, depending on how >>much energy you can invest) C at these speeds, a small mass flow is >>sufficient to slow us down (or speed us up depending on which phase of >>the mission we are in) at a constant 1 G. > >>> This was clear to me, but rethinking this made me >>> realize that your method can't work. Because adding >>> momentum to the Asimov will only make it move >>> faster. Transforming it to reverse momentum would >>> surely break one of the basic physic laws. > >No Tim. The momentum of the microwave is simply added load on the antena >support structure (which is an extreamly unlikely structure) assuming it can >take the load the power (electric) them feeds the engines which use it to >produce forward or backward thrust. No violation of conservation of >momentum. As long as the engine is powerful enough (and antenna strong >enough) to overcome the thrust load of the photon sail effect of the big >antenna. Every thing is fine. >> >> No, that's not what I meant. I think that the energy that is gained by >> >> receiving the photons is not enough to overcome the velocity gain that you >> >> get by receiving these photons. So a powerful engine doesn't work because >> >> there isn't enough fuel. This can't be right. If it was no solar electric drive could ever work. Besides it sounds like you have a conservation of energy contradiction here. Subject: Solar array ReplyTo : Kelly ReplyFrom: Timothy >Are you talking about a 5 kilometer disk a million kilometers from the suns >surface? Does this not strike you as a servicing problem? In fact I was talking about a 50 kilometre disc... >Solar Power Density out here by earth is 1.35 KW/m^2 not the 5E8 Watt/m^2, >but the equipment will be a lot more likely to keep working. >> I agree completely, but having it so near Earth means a much bigger array. >> 5E8/1.35E3=3.7E5 times bigger to be exact. That is about 1.5 times the >> surface of the Earth!!! That seems to be an even bigger problem :) Ok, eiather system is infeasable. Kelly From popserver Tue Nov 14 01:58:01 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1318" "Mon" "13" "November" "1995" "17:53:32" "-0800" "Steve VanDevender" "stevev@efn.org" nil "32" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA10462; Mon, 13 Nov 95 17:52:43 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id RAA11645; Mon, 13 Nov 1995 17:53:32 -0800 Message-Id: <199511140153.RAA11645@tzadkiel.efn.org> In-Reply-To: <951113191409_21423872@mail06.mail.aol.com> References: <951113191409_21423872@mail06.mail.aol.com> X-UIDL: 816314212.001 From: Steve VanDevender To: KellySt@aol.com Cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Engineering Newsletter Date: Mon, 13 Nov 1995 17:53:32 -0800 KellySt@aol.com writes: > to: rddesign@wolfenet.com > To: KellySt@aol.com > > >>> Heat load on the asimov: > > > >> Kelly > >> This is way outside of my knowledge but couldn't this heat > >> be expelled like exhaust and added to the thrust? Heat is > >> just hot particles, isn't it? > > No such luck. Heat is eiather the thermal vibration of the molecules in an > object, or infared radiation (life in a radiative heater). Can't think of > how we'ld pump all the heat out of the ship fast enough to keep it cool. Heat is purely statistically random molecular motion. Infrared radiation is just a form of radiation that is good at inducing heat in common materials. Regarding this whole momentum-transfer issue, in some far-distant posting to the newsletter I pointed out that a reflective sail is the most efficient option for accelerating a spacecraft with beamed power; it changes photons with momentum +p into photons with momentum -p, and thereby increases the spacecraft momentum by 2p. It is unlikely that you could absorb the photons and use them to power a mass driver with greater efficiency than the reflectivity of a mirror. Using beamed power to decelerate a ship that's going in the same direction as the photons is more problematic. At best the efficiency is going to be bad. From popserver Wed Nov 15 03:51:19 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4909" "Tue" "14" "November" "1995" "21:09:22" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "139" "EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA29318; Tue, 14 Nov 95 19:09:19 PST Received: by maroon.tc.umn.edu; Tue, 14 Nov 95 21:09:23 -0600 In-Reply-To: <199511140153.RAA11645@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 816407391.009 From: Kevin C Houston To: Steve VanDevender Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl Subject: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-) Date: Tue, 14 Nov 1995 21:09:22 -0600 (CST) On Mon, 13 Nov 1995, Steve VanDevender wrote: > Regarding this whole momentum-transfer issue, in some far-distant > posting to the newsletter I pointed out that a reflective sail is > the most efficient option for accelerating a spacecraft with > beamed power; it changes photons with momentum +p into photons > with momentum -p, and thereby increases the spacecraft momentum > by 2p. It is unlikely that you could absorb the photons and use > them to power a mass driver with greater efficiency than the > reflectivity of a mirror. > Agreed. > Using beamed power to decelerate a ship that's going in the same > direction as the photons is more problematic. At best the > efficiency is going to be bad. > It is, which is why I proposed a linear accelerator in the first place. _BUT_ (drum roll please) I HAVE SOLVED THE PROBLEM OF SLOWING DOWN!!!! (Okay, Okay, I'll calm down now. And promise not to be so smug for the rest of this message) To Review: The main problem is that the momentum of the recieved photons is greater than the emitted exhaust. This is as it should be, the exhaust can't travel at C, and besides there's always losses. Solar electric space craft work because the ejected ion stream is traveling at far less than the speed of light, so the energy needed is less. and besides, the light is almost never coming from straight behind. But I digress. First, there is _no_ way to reduce the momentum imparted by the photons. However, we _can_ change the _direction_ of the thrust. or to paraphrase an old Chinese proverb. You can't change the direction of the wind, but you can adjust the sail. Do you see it yet? the solution? Tilted sail. Physical Design. (highly stylized ascii art) ////////// \\\\\\\\\\ <---- Sail elements |~~| | | <- ship Note: support cables omitted | | | | y | | ^ | | Energy is beamed from below in this | | | diagram. |--> x | | |__| The Sail (and it is a sail for most of the flight) is made of concentric conic sections tilted at 76.6 degrees (more on this later) this changes the direction of the imparted velocity, and since the sail elements have a circular symetry, the x componets of the force cancel out. A Force Balance on one sail element: Velocity y / <-- Sail element Vector\ component / \ | / \ | / \ | / \ | / \ | / x component_________\|/ / angle T (for theta) / / ________________________ There is another element on the other side of the ship whose x component cancels this one. The y component is Fy=F*cos (T) where F equals E/c. Some constants: c - Speed of Light (of course) = 3.0 E+08 m/s Ms - Mass of ship (RM neglected for now) = 2.5 E+09 Kg G - Ship's Gravity = 10 m/s^2 Ve - Exhaust velocity = .9996 c Eb - Beamed energy = 3.24 E+19 Watts Pe - Engine Thrust = 2 G T - angle of sail elements = 76.6 degrees (this value was found by trial) (and error and is critical ) Some equations: Photon Thrust(Newtons) Pp = E / c * cos (T) / Ms Pp=3.24E+19 / 3.0 E+08 * cos (76.6) / 2.5 E+09 = 10 m/s^2 Exhaust Mass (Kg/sec) Me = Pe * Ms / (Ve * c) Me = 20 * 2.5 E+09 / (0.9996 * 3 E+08) = 166.73 Kg/sec Exhaust Rest Mass (Kg/sec)Mr = Me * SQRT(1- Ve^2) Mr = 166.73 * Sqrt (1-0.9996^2) = 4.72 Kg/sec Kinetic Energy in Exhaust Ke = 1/2 * Mr * (Ve *c)^2 Ke = 1/2 * 4.72 * (0.9996 * 3 E+08) = 2.12 E+17 Relativistic Energy Er = (Me-Mr)*c^2 Er = (166.73 - 4.72) * 3 E+08^2 = 1.46 E+19 Total energy needed Et = Er + Ke Et = 2.12 E+17 + 1.46 E+19 = 1.48 E+19 Energy Available Ea = Eb * .8 (conversion losses) Ea = 3.24 E+19 * .8 = 1.66 E+19 And as you can see, the energy Available exceeds the energy needed. No physical laws get broken. During the Accel phase, the engines are quiet. The "Asimov" accelerates by reflected maser power (the transmitters operate at 1/2 power because the "Asimov" is Reflecting the maser, not Absorbing it like the above equations assume. This solution is more expensive (in terms of energy and sail area) it has a few extra benefits: the radial force component (x in the above force diagram) allows us to use tensile forces to hold the sail together (yes, it's a lot of force, but I think it is possible to do from an engineering standpoint) Kevin From popserver Wed Nov 15 14:33:27 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["11732" "Wed" "15" "November" "1995" "15:22:36" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "276" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA27839; Wed, 15 Nov 95 06:22:11 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA06167 (5.67b/IDA-1.5 for ); Wed, 15 Nov 1995 15:22:20 +0100 Message-Id: <199511151422.AA06167@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=====================_816470556==_" X-Attachments: C:\RAY.GIF; X-UIDL: 816445922.005 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Wed, 15 Nov 1995 15:22:36 +0100 --=====================_816470556==_ Content-Type: text/plain; charset="us-ascii" The first part of this letter has been retarded a few days because of a bad working mail-demon... I added the newer part after the first two older messages. Subject : Photon energy ReplyTo : Timothy ReplyFrom: Kevin >All these formulas have me confused, let me see if I can work this out >using some real (made-up) numbers. assume E=1 E+19 Watts, mass of "Asimov" >= 2.5 E+09 Kg, wavelength of beam = 21 cm. >I think we both agree that during the accel phase, the momentum from the >photons helps us accelerate. But you are saying that the momentum of the >photons is more than the momentum of the exhaust stream during the >decelleration phase. hmm. let's see... > >p=E/c therefore p=3.34 E+10 Kg m/s the "Asimov" masses at 2.5 E+09 so >if p=m v then v=p/m and v, (the amount of velocity change) = 13.34 m/s so >every second that the beam is on us, we get "pushed" toward T.C. at 13.34 >m/s faster than we were before. > >now let's use that energy we absorbed (minus 20% for conversion losses, >now E= 8 E+18) to accelerate some amount of material to allow us to slow >down. to find out how much material (per second) we must eject, let's use >the rocket equation first. the apparent mass Ma (as seen by the crew) of the >exhaust is g * M /Ve * c where Ve is .9996 and g is 23.34 (10 m/s^2 for >us, and 13.34 m/s^2 to counteract the photonic thrust) so Ma= 194.71 Kg/sec >moving at .9996 of c. note that this is only 3.89 Kg out of the tanks so >thus the rest mass of the exhaust is 3.89 Kg/sec. > >Now let's see how much energy it takes to accelerate 3.89 Kg to .9996 of c >the energy will equal the kinetic energy of accelerating the mass to the >required speed, plus the energy of the "mass increase" E=Ke + Re >Ke=1/2 m v^2 = 1/2 *3.89* (.9996*c)^2 = 1.74 E+17 >Re= m c^2 = (194.71 - 3.89) * c^2 = 1.71 E+19 > >total energy required = 1.73 E+19 < Some text left out> >Okay, Okay, I see your point (finally). so we can speed up, but we can't >slow down even using beamed power. unless we use a retro reflecting ring >sail, and that seems like such a waste I'm happy to hear this. Unfortunately your conclusion was based on wrong calculations. I will explain here: You used: g * M /Ve * c but that formula is non relativistic. The right formula would be: g * M /(Ve * c * gamma) This gives the mass exhaust per second. That mass does not need to be translated to 'out of the tanks'-mass. After that you use a strange and wrong method to calculate the needed energy. The right formula for kinetic energy would be: E=m c^2 (gamma-1) (You don't need to create the rest energy, that part is already onboard the ship in the form of mass) So re-doing your first calculation: Take a=13.34 m/s^2 (this is the minimum to get even with the received photons) gamma=35.36 for v=0.9996c (gamma=1/SQRT(1-v^2/c^2) m/t=M a/(gamma Vexh) = 2.5E9 13.34/(35.36 0.9996 c) = 3.15 Kg needed E=m c^2 (gamma-1)=3.15 c^2 (35.36-1)= 9.73E18 So 1E19-9.73E18=2.7E17 Watt left over, that will give an acceleration of about 0.38 m/s^2 (This all assumes 100% efficiency) So I was not completely right saying it was impossible, but very efficient is it certainly not. I'm very happy that you tried to do the calculations, it makes it easier to find the difficulties. From my physics background I'm used to do more in formulas and less in numbers. Next time I will try to remember and use some numbers also. Subject : Solar array ReplyTo : Kevin ReplyFrom: Timothy >> But it won't reduce the total solar array, which is really big: >> >> Total Solar Power : 4E26 Watts > >Not really all that much more than the power a 2.5 E+09 Kg ship needs to >get up to lightspeed in a decent amount of time. I think the ship needs >to go on a diet! There is still a factor 1E5 involved. That is still much more, so a diet is not necessary and not possible if we want a relativistic ship. Meaning our ship could be 1E5 times heavier. >> Mean amount of power needed by the Asimov : 1E18 Watt >> -> Size of solar array : 1E18/5E8 = 2E9 square metres >> = disc with radius 2.5E4 metres. >> >or 1000 disks with radius of 25 metres (Okay, Okay, a little more than 25 >meters, but you get the point.) You mean 1.000.000 disks with radius of 25 metres! 1000 disks or 1 million disks that makes quite a difference. >> Remember 1E9 metres is quite near Sol. You wouldn't like to be there in your >> space suit, because 5E8 Joules would be added to your body temperature every >> second. > >No one would be there, the transmitters would be built near earth, and >launched into close solar orbit. if one or another fails, you launch >another one rather than try and fix it. I agree. But launching 1 million disks? Two other problems I could think of: - Any black spot on the solar array will probably melt away. - Each disk would be about 6 kilometres apart if they are in the same orbit. ------------------------------------------------------------------------------ NEWER PART ------------------------------------------------------------------------------ ReplyTo : Keving ReplyFrom: Timothy Subject : The bathtub is flowing over (EUREKA) >I HAVE SOLVED THE PROBLEM OF SLOWING DOWN!!!! First convince me... then celebrate... >First, there is _no_ way to reduce the momentum imparted by the photons. >However, we _can_ change the _direction_ of the thrust. NO and yes, you cannot change the initial size and direction of the photon thrust, but you can (of course) choose the direction of the thrust when transmitting a photon. In better words: You should see the reflection of a photon as two steps, independant of each other. The first step is receiving the photon where momenum to your mirror is added in the same direction as the photon CAME FROM. The second step is transmitting(reflecting) the photon, hereby is the momentum of the photon added in the opposite direction the photon GOES TO. So if you shoot a photon from the negative x direction to a mirror which is has 45 degree angle(on the x=y line) it first gets the momentum p in the x direction and second the momentum p in the y direction. This makes a total momentum of Sqrt(p^2+p^2)=Sqrt(2)*p in the xy direction. ^ | y | / | ______|/ | / +--- x / >Total energy needed Et = Er + Ke >Et = 2.12 E+17 + 1.46 E+19 = 1.48 E+19 > >Energy Available Ea = Eb * .8 (conversion losses) >Ea = 3.24 E+19 * .8 = 1.66 E+19 I think I know what you mean: (better formulas, see the previous message) Pp=10 m/s^2 Mr = Pe*Ms/(gamma Ve *c) = 20*2.5E9/(35.4 0.9996 3E8) = 4.72 Kg/sec Et = Me c^2(gamma-1) = 4.72 9E16 (35.4-1)=1.46E19 So, indeed much less than 3.24E19 But now how do you capture the photons? You are talking about mirrors (sail) all the time but not about capture. (I included a GIF-image of how I think you would do that) I still don't know why you used an angle of 76.6, doing the calculation with an angle of 85 degrees you need even less energy. My guess is that you forgot the capturing of the photons and therefore forgot to add momentum somewhere. You tried to trick the photons and thereby violated the preservation of momentum: If you receive an amount of photons, all their momentum is transferred to you. Once more, whatever ingenious construction you can think of, to receive a certain amount of photons and use their energy, you ALWAYS get ALL their momentum in the same direction as they went to. ReplyTo : Kelly ReplyFrom: Timothy Subject : Drawings >I was thinking of having the shielding in a fixed U shaped shielding trough >that runs around the inside of the outer hull (the open end of the U points >inward). If the shielding is made of steel instead of lead, the hab >centrafuge tracks can run around on the top edges of the U. (of course the >steel would be at least 3 feet thick!) That seems to be almost the same as what I wrote. OK. >>> (Tip: jpeg images would be about 4 times smaller, so would >>> mean a less bytes with almost the same image quality) > >Now if Rick would get a JPEG viewer. ;) I can't help with that, I don't know much about Mac-computers and their software. ReplyTo : Kelly ReplyFrom: Timothy Subject : Multi generation ship >Of course instead of a 5 year (ship time) trip, your talking about centuries >to thousands of years, and a crew 10-1000 times larger, and a proportianatly >larger ship, etc... You might make an energy savings, but it wouldn't be as >dramatic as you might expect. Hmm, yes you're right when using these numbers. But remember, my approach was VERY rough. In fact each human needs about 1.3E7 joules per day (=4.7E9 Joules per year). In the previous calculation I assumed Earth's biosphere balance. Which seems to be quite inefficient if it was designed only to keep people alive. Assuming Earth's biosphere and 100 square metres per person (which may be less) I calculated that every person used 4.4E14 Joule per year. So this means an efficiency of 0.001 % (My guess is that we could do far better that that.) >Building things takes skills, tools, and materials, as well as power. Of >course we didn't give the ship tremendous power reserves. The power needed to build the ship can probably be neglected with respect to the energy needed for the 1000 year trip. Materials should be mined at those asteroids. After the ship is build these mining-plant could be sold for much money if necessary. Tools could be made there or on Earth where ever it is cheapest. About the skills, I'm not sure. I guess working in space has to be common before we can build any interstellar ship. --=====================_816470556==_ Content-Type: application/mac-binhex40; name="RAY.GIF" Content-Disposition: attachment; filename="RAY.GIF" (This file must be converted with BinHex 4.0) :"e*"@5j(58B!3NP13@eNEh-!!!!!",-!!!!!lXP(58Bi0f(L!+X!J!!!!!!!rrr r,!!!!!$L!+X!!!,rM)qTbqd2SjbdfSZchVcl$iEL5*EQLCi!N!#flJZ(DdcApSh RqSkaFr",V&L+f6!)p"f&4q,"Z14*TmdSBVLSBJhDB2IkRBTcA56A#8ClNErYfHP 1MZHf0Y%X,k,e$IbD$NKf0mKAb)$hY*Hh'0J)BhGQ#1D!'-Q8k*Mj!XPSHGQRQ+M fTeQU3XKBpANB+YSdD4Sl`XRf#X[kS(SVbp[Vq`XF,$`-A%QXBA`XNLc-$!V5UY` TlB`,,Cd9M9e46D'pDCYQ&ICQjBNC'9lH[4lARKfU*Hk1,+ME[PAQkZi(4di13Gm qH[55h*2Ri4X+IYSiLGS&F9%F1h[@(+a)-BdNG2p[)RC3D-*CQ(iHTj'#Kp"J1*) Q&5%b8f[@$@B#@Ck,H&*2bS!Z8H'-Kl%N"j!!**+aR"JcQb&Ml1"TE,RaCY*PG@$ k4#H3!#168Ij!%8@jXPC2TEZDFUYkFD35JZT8KU@d-pGDUrIH344EX"jDKJLVYA8 Vm9YGRMc0fGADkHp3@@DTI2AeH%FEaT&j9HCaZH-fbCBR$0j-CSjK,R,cJXBXCM" 3dkG61kilYh&VcTMlXTkY+A24Z+0aPp)Y)qY@i,jV%%mSh&Ta4mFr*PpHc&jFk,q DEbKMR6VY[CqepmVHilRhld*FB!FrIQEj&)08b8j2jFT#I`IK3jBIFVLjprC$Nrr H$9Bmr6ALdRp8H480I`1bTiD"ehbd)#!0!J%0H1K&@1&rf9di$BD5q8$K8"`qiD& S)&l(B)QT'5AA*LSkeNFZ00$dSRNahQLFM$A@m3`1$Hh)BaDei3LNM9(j9d54,LC TST!!5V,(T)412PP#8-a&5D9-*2j@8CCDGRMPPPjq!%GeCBkC%*LaR)PQ250@&@+ E'5JSjCX[dKN)RPRD1D5FCmh'ji*kCK,SJ)-b9bKm*lCfU)Thi,DSRiFi#0UMNNk CU!k@AVTHR+HabDQRQ5)j+U5GISSITed#HUUF"E+DUTq[-SSPQJ,#'ZZBVC5UAUe l6STVUdmQD1U8[`*,+l,$re*5V,'AmKUNXT*#Qf1S1LCV,C'9CXYXX0`+Z`fefSN E!lR3QE[NYlk'UkkcQk&E(,`Yb0XXUZf#L`fphVjl,ll+0,UM[L%*r#R"XaJF,X" M+0&[1YXUl#')#+G*iF6%R'JaLL&Q(*fRe'c*F620KY`aYJf6$'($P2+VXXFXUic bBLh(V$(-pIC,XeiflpYZcR1fl$+l-ppmVmmp!'hd"8PhaV1k5rqjXmNi%pdce8j ErHh6hJ$YQpCFI`eff'+26AECCTq0GYTUV`fCef[M#6(ERKdAYp`4`1ffUR6RA54 !8,bNcR4ZBD3BA)$0-e8UKCrl$fmT6HHhi!L'pIJS!j,9E3TGQKRd81FhHFlj1@j %ERQ2PL4Zk&L*GE8+Q$CCGARTNb-PHRI8(@8P9)MYRT1D4mC1H%q,abZ@9+bAYD[ UUmpY1Q+p#89mjDXJ*IY@6bd[!92+lrllFRqMMTGKUZd%HrB*2YH2lGihP2YKmqM %81XYcKjrJ2eK2Jcqrr)0S0hqr`r!!!T`J!3XS!%2Q,B#Y!!lVcd!!!: --=====================_816470556==_-- From popserver Thu Nov 16 03:44:50 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3614" "Wed" "15" "November" "1995" "22:25:06" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "96" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA16952; Wed, 15 Nov 95 19:25:12 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id WAA11785; Wed, 15 Nov 1995 22:25:06 -0500 Message-Id: <951115222503_23751735@emout05.mail.aol.com> X-UIDL: 816493287.054 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com Subject: Re: Engineering Newsletter Date: Wed, 15 Nov 1995 22:25:06 -0500 ReplyTo : Keving ReplyFrom: Timothy Subject : The bathtub is flowing over (EUREKA) >I HAVE SOLVED THE PROBLEM OF SLOWING DOWN!!!! >> First convince me... then celebrate... >First, there is _no_ way to reduce the momentum imparted by the photons. >However, we _can_ change the _direction_ of the thrust. >> NO and yes, you cannot change the initial size and direction of the photon >> thrust, but you can (of course) choose the direction of the thrust when transmitting a photon. >> In better words: >> You should see the reflection of a photon as two steps, independant of each >> other. The first step is receiving the photon where >> momenum to your mirror is added >> in the same direction as the photon CAME FROM. >> The second step is transmitting(reflecting) the photon, hereby is the >> momentum of the photon added in the opposite direction the photon GOES TO. >> ----- Can't follow your argument, and the deleated graph seemed countradictory. I thing the fundemental part of kevins argument is correct. That the thrust vector on a photon sail is tangential to the surface of reflection, and the amount is related to the angle of incidence of reflection. (thats one of the standard solar sailing tricks.) If of course you absorb the photons in a rectena array the result is a bit less clear, but presumably you could reflect the energy off the sail to converters, at an angle that would cut down the forward thrust. The price of this would be a lot of extra thrust, and stress, on the guy wires. >> You tried to trick the photons and thereby violated the preservation of >> momentum: If you receive an amount of photons, all their momentum is >> transferred to you. Yes, but if it is transfered at an angle; part the momentum will be disapated in the structure, rather than acting to accelerate the ship. >> Once more, whatever ingenious construction you can think of, to receive a >> certain amount of photons and use their energy, you ALWAYS get ALL their >> momentum in the same direction as they went to. Define went to? ReplyTo : Kelly ReplyFrom: Timothy Subject : Drawings >>> (Tip: jpeg images would be about 4 times smaller, so would >>> mean a less bytes with almost the same image quality) > >Now if Rick would get a JPEG viewer. ;) >> I can't help with that, I don't know much about >> Mac-computers and their software. Huh?? Well as a hint you generally need to have a copy before you can use it. ReplyTo : Kelly ReplyFrom: Timothy Subject : Multi generation ship ----- >Building things takes skills, tools, and materials, as well as power. Of >course we didn't give the ship tremendous power reserves. >> The power needed to build the ship can probably be >> neglected with respect to the energy needed for the >> 1000 year trip. Materials should be mined at those >> asteroids. I wasn't talking about the energy to build the ship. I was talking about the energy, resources, and equipment needed to continually rebuild it in flight. Equipment has a life span too, and none if it will function for a thousand years. The ship will have to not only be equiped with its own internal ship yard, but with all the manufacturing facilities needed to build every part, and every tool in the complete ship. Then you have to bring along all the raw materials and fuel they'll need for the trip. Then you have to staff it with all the people with all the specialties needed to do all of that. The ship would need a degree of selfsuficency that no country, much less industrial country, on Earth has had in generations. Kelly From popserver Thu Nov 16 03:44:53 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2105" "Wed" "15" "November" "1995" "22:25:20" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "48" "Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA17002; Wed, 15 Nov 95 19:26:13 PST Received: by mail04.mail.aol.com (8.6.12/8.6.12) id WAA28195; Wed, 15 Nov 1995 22:25:20 -0500 Message-Id: <951115222515_23751943@mail04.mail.aol.com> X-UIDL: 816493287.055 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org Cc: rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl, david@interworld.com Subject: Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-) Date: Wed, 15 Nov 1995 22:25:20 -0500 VERY NICE KEVIN!!! You delt with the structural and thrust problems at once! I'll call you later, but wanted to send a couple of ideas right away. I still have questions about momentum transfer vs power absorbsion. This neat conversion of absorbed power and momentum bothers me. I would think that converting the power would use up the energy that would generate the thrust. Maybe I'm confused? If the back side of the sail/collector was mirrored, and the frount side of the inner sail elements had the rectennas. Then durring the accel phase all sail elements can be trimed to reflect almost all the power straight back at Sol for max thrust. (Note you'll need a slight outward thrust to hold the sails out to the sides.) Durring the decel phase. The outer sails are trimed to reflect their energy inward toward frount of the inner sails. The inner sails are trimed to reflect the energy hiting their back inward toward other sails or dumping it. But this foward and outward thrust, serves to support them against backward and inward thrurst from the energy pouring inward and back from the outer sails onto the frount of the inner sails. The frount of the inner sails have the rectenna arrays. Which absorb and convert the microwaves. Good news. The sails have max reflectivity durring accel phase. Only the inner sail array needs the more complecated rectenna and power conversion/transmition/cooling equipment. (The outer segments are just wire mesh.) So servicing and costs can be minimized. Bad news The expensive power converters are going to be face first into the inter stellar medium, and they are going to be operating at much higher power densities. Cooling is going to be much harder. Weird thought. Am I right that microwaves can impart thier momentum on ions directly? Could you channel the power via waveguides, and feed the reaction mass into the power stream and get it to accelerate the plasma directly? I can't remenber it clearly, but I think their is some such mechanism. If so, you could avoid the heating problems of the power conversion step. Kelly From popserver Fri Nov 17 00:17:49 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5329" "Thu" "16" "November" "1995" "22:37:32" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "116" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA22866; Thu, 16 Nov 95 13:37:29 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA23535 (5.67b/IDA-1.5 for ); Thu, 16 Nov 1995 22:37:11 +0100 Message-Id: <199511162137.AA23535@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 816567351.020 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Thu, 16 Nov 1995 22:37:32 +0100 ReplyTo : Kelly ReplyFrom: Timothy Subject : The bathtub is flowing over (EUREKA) >>I HAVE SOLVED THE PROBLEM OF SLOWING DOWN!!!! > >>> First convince me... then celebrate... > >>First, there is _no_ way to reduce the momentum imparted by the photons. >>However, we _can_ change the _direction_ of the thrust. > >>> NO and yes, you cannot change the initial size and direction of the photon >>> thrust, but you can (of course) choose the direction of the thrust when >transmitting a photon. > >>> In better words: >>> You should see the reflection of a photon as two steps, independant of >each >>> other. The first step is receiving the photon where >>> momenum to your mirror is added >>> in the same direction as the photon CAME FROM. >>> The second step is transmitting(reflecting) the photon, hereby is the >>> momentum of the photon added in the opposite direction the photon GOES TO. >>> ----- > >Can't follow your argument, and the deleated graph seemed countradictory. I >thing the fundemental part of kevins argument is correct. That the thrust >vector on a photon sail is tangential to the surface of reflection, and the >amount is related to the angle of incidence of reflection. (thats one of the >standard solar sailing tricks.) Agreed, completely. But if you want to use all the photon's energy you have to stop them. Stopping them makes the ship go forward. Kevin tried to change the direction of the photons in a way that stopping them would not add to forward but sideward momentum. Doing the same thing for the other sideward momentum cancelled out the movement to either side. But as soon as you change the direction of a photon a little you get a small forward thrust. But if you want to change the direction so much to use Kevin's trick, then you have the same forward thrust as you would have if you captured the photons immediately. I referred to Kevin's trick. I'm still not completely sure if I understand Kevin's idea correctly since I don't know how and where he want to tap the photons' energy. >If of course you absorb the photons in a rectena array the result is a bit >less clear, but presumably you could reflect the energy off the sail to >converters, at an angle that would cut down the forward thrust. The price of >this would be a lot of extra thrust, and stress, on the guy wires. Reflecting the photons to another direction adds some forward momentum to the ship. And as soon as you stop the photons in the converters, you transfer the rest of the forward momentum of the photons! >>> You tried to trick the photons and thereby violated the preservation of >>> momentum: If you receive an amount of photons, all their momentum is >>> transferred to you. > >Yes, but if it is transfered at an angle; part the momentum will be disapated >in the structure, rather than acting to accelerate the ship. In that preservation also the direction is mentioned. So if before the absorption you have a forward momentum, than that momentum should be there after the absorption still in forward direction only now transferred to the ship. >>> Once more, whatever ingenious construction you can think of, to receive a >>> certain amount of photons and use their energy, you ALWAYS get ALL their >>> momentum in the same direction as they went to. > >Define went to? Went to = The direction of the photons before they encountered the Asimov. ReplyTo : Kelly ReplyFrom: Timothy Subject : Drawings >Huh?? Well as a hint you generally need to have a copy before you can use >it. I use an IBM-compatible computer and have programs to convert many image-formats. I assumed that for Mac computers there would be similar programs. ReplyTo : Kelly ReplyFrom: Timothy Subject : Multi generation ship >The ship would need a degree of selfsuficency that no country, much less >industrial country, on Earth has had in generations. Ah now I see what you mean. The industry on the ship would be completely different than that on Earth. The different production lines should be very generalized and not specialized. This means that one line can do all kinds of synthetic material moldings. Probably this results in a less efficient line. Not less efficient with energy but with time. My guess is that time is not the most important factor here. Another important thing would be automation of the production process. A lot of equipment would be made many times again, so then automation would ease the job. About specialties, of course it would be easier if we had specialist for everything but one person in a certain field can do a lot if he/she has the right information available. Again that would mean less efficient with time. But don't forget, on Earth lots of energy and manpower is used to innovate. The thing that we are concerned most about, is to keep what we have. Rebuilding what one has is a lot easier than creating new things. To keep up with Earth's technology we could simply copy what they had created. Furthermore almost all equipment should be recycled, a lot of energy can be spared if the equipment is designed for easy recycling. So this will and should reduce the need for raw materials a lot. Maybe we can recycle some of the energy if we enclose the ship with a kind of thermos flask and use heat exchangers to re-use some of that energy. From popserver Sun Nov 19 22:21:24 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["2933" "Sun" "19" "November" "1995" "16:14:37" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "65" "Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA12227; Sun, 19 Nov 95 14:13:51 PST Received: by maroon.tc.umn.edu; Sun, 19 Nov 95 16:14:37 -0600 In-Reply-To: <951115222515_23751943@mail04.mail.aol.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 816819575.000 From: Kevin C Houston To: KellySt@aol.com Cc: stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl, david@interworld.com Subject: Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-) Date: Sun, 19 Nov 1995 16:14:37 -0600 (CST) On Wed, 15 Nov 1995 KellySt@aol.com wrote: > I still have questions about momentum transfer vs power absorbsion. This > neat conversion of absorbed power and momentum bothers me. I would think > that converting the power would use up the energy that would generate the > thrust. Maybe I'm confused? > Not at all, if you reflect, you get twice the momentum that you'd get if you absorbed. so there is no violation of energy conservation. > > > If the back side of the sail/collector was mirrored, and the frount side of > the inner sail elements had the rectennas. Then durring the accel phase > all sail elements can be trimed to reflect almost all the power straight > back at Sol for max thrust. (Note you'll need a slight outward thrust to > hold the sails out to the sides.) > > Durring the decel phase. The outer sails are trimed to reflect their > energy inward toward frount of the inner sails. The inner sails are trimed > to reflect the energy hiting their back inward toward other sails or > dumping it. But this foward and outward thrust, serves to support them > against backward and inward thrurst from the energy pouring inward and > back from the outer sails onto the frount of the inner sails. The frount > of the inner sails have the rectenna arrays. Which absorb and convert the > microwaves. > > Good news. > The sails have max reflectivity durring accel phase. > > Only the inner sail array needs the more complecated rectenna and power > conversion/transmition/cooling equipment. (The outer segments are just > wire mesh.) So servicing and costs can be minimized. > > Bad news > The expensive power converters are going to be face first into the inter > stellar medium, and they are going to be operating at much higher power > densities. Cooling is going to be much harder. > 1) about power converters (schottsky diodes) being face first into the "wind" we are going to need a lot of tension wires to keep the antenna from blowing apart, so if they were on the front, they would effectivly shield the diodes. 2) about cooling, angling the antennas requires more surface area, allowing for _smaller_ power densities, and more surface to radiate the heat. > > Weird thought. Am I right that microwaves can impart thier momentum on > ions directly? Could you channel the power via waveguides, and feed the > reaction mass into the power stream and get it to accelerate the plasma > directly? I can't remenber it clearly, but I think their is some such > mechanism. If so, you could avoid the heating problems of the power > conversion step. Agreed, this should be looked into. Not sure if this is possible with microwaves, I'm having difficulty seeing how the microwaves could be reflected into the reaction chamber without the inner sail elements getting in the way of the outer ones. but if it could be made to work, it would solve the heat problem neatly. From popserver Mon Nov 20 10:11:18 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3499" "Mon" "20" "November" "1995" "02:08:27" "-0800" "Steve VanDevender" "stevev@efn.org" nil "73" "Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA11205; Mon, 20 Nov 95 02:06:45 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id CAA01303; Mon, 20 Nov 1995 02:08:27 -0800 Message-Id: <199511201008.CAA01303@tzadkiel.efn.org> In-Reply-To: References: <951115222515_23751943@mail04.mail.aol.com> X-UIDL: 816862166.000 From: Steve VanDevender To: Kevin C Houston Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl, david@interworld.com Subject: Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-) Date: Mon, 20 Nov 1995 02:08:27 -0800 Kevin C. Houston writes: > On Wed, 15 Nov 1995 KellySt@aol.com wrote: > > > I still have questions about momentum transfer vs power absorbsion. This > > neat conversion of absorbed power and momentum bothers me. I would think > > that converting the power would use up the energy that would generate the > > thrust. Maybe I'm confused? > > > > Not at all, if you reflect, you get twice the momentum that you'd get if > you absorbed. so there is no violation of energy conservation. This is not strictly true. In fact, I've been quite dubious of Kevin's claim that his configuration of solar sails would really produce deceleration. In fact, I believe that you can't use a static sail (that is, one permanently attached to the spacecraft) to decelerate, as to produce deceleration the reflected photon must increase in momentum to compensate for the spacecraft decreasing in momentum; the static sail is tied to the spacecraft so it cannot change its momentum separately from the spacecraft. The previously-mentioned "Dragonfly" sail (from Robert L. Forward's _Flight of the Dragonfly_) accomplishes deceleration by splitting the sail into a retro-reflecting portion that focuses energy back to the remaining portion of the sail attached to the spacecraft; in this case the retro-reflecting sail increases in momentum to compensate for the spacecraft's decrease in momentum, and thereby ends up carrying all of the momentum from the beamed power by the time the spacecraft has come to "rest". Consider a photon with momenergy [ p, p, 0 ] (that is, energy p, momentum p in the x direction, no momentum in the y direction), incident on a mirror with initial momenergy [ m, 0, 0 ] tilted at an angle theta, such that when theta = 0 the mirror reflects the photon straight back along its original path, and positive theta means counterclockwise rotation of the mirror. After reflection, the photon has momenergy [ p, -p * cos(2 * theta), -p * sin(2 * theta) ], and to conserve momenergy the mirror must then have momenergy [ m, p * (1 + cos(2 * theta)), p * sin(2 * theta) ]. (the total system momenergy remains [ m + p, p, 0 ]). You'll note that the expression (1 + cos(2 * theta)) is always greater than or equal to 0. In other words, the x-component of the mirror's momentum after reflection is always forward, or at best nil. So you can steer by tilting the sail, but you can't slow down. If you use multiple reflections, then you can analyze the behavior simply by considering the final photon momentum after the reflections. In the case of a double reflection that leaves the photons travelling in the same direction they originally were (maybe parallel to their original course) then there is _no_ net change in spacecraft momentum. If you change the direction of the photons, then you must _always_ leave them with a smaller x-component of momentum than they originally had, and this results in increased x-momentum for the spacecraft. You may be able to decrease the efficiency of the sails as much as you want, but you will never produce deceleration with multiple-reflection schemes as long as the sails are attached to the spacecraft and therefore tied to the spacecraft's momenergy. A really thorough treatment of multiple reflections would have to consider both the finite speed of light and the finite speed of propagation of changes in velocity through the spacecraft structure; for very high rates of acceleration these would be significant effects. From popserver Mon Nov 20 10:38:53 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4659" "Mon" "20" "November" "1995" "04:35:36" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "93" "Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA11737; Mon, 20 Nov 95 02:34:39 PST Received: by maroon.tc.umn.edu; Mon, 20 Nov 95 04:35:36 -0600 In-Reply-To: <199511201008.CAA01303@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 816863821.000 From: Kevin C Houston To: Steve VanDevender Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl, david@interworld.com Subject: Re: EUREKA!!!!!!!!!! (ha ha ha ha ha ha) >:-) Date: Mon, 20 Nov 1995 04:35:36 -0600 (CST) On Mon, 20 Nov 1995, Steve VanDevender wrote: > Kevin C. Houston writes: > > > On Wed, 15 Nov 1995 KellySt@aol.com wrote: > > > > > I still have questions about momentum transfer vs power absorbsion. This > > > neat conversion of absorbed power and momentum bothers me. I would think > > > that converting the power would use up the energy that would generate the > > > thrust. Maybe I'm confused? > > > > > > > Not at all, if you reflect, you get twice the momentum that you'd get if > > you absorbed. so there is no violation of energy conservation. > > This is not strictly true. In fact, I've been quite dubious of > Kevin's claim that his configuration of solar sails would really > produce deceleration. In fact, I believe that you can't use a > static sail (that is, one permanently attached to the spacecraft) > to decelerate, as to produce deceleration the reflected photon > must increase in momentum to compensate for the spacecraft > decreasing in momentum; the static sail is tied to the spacecraft > so it cannot change its momentum separately from the spacecraft. > The previously-mentioned "Dragonfly" sail (from Robert L. > Forward's _Flight of the Dragonfly_) accomplishes deceleration by > splitting the sail into a retro-reflecting portion that focuses > energy back to the remaining portion of the sail attached to the > spacecraft; in this case the retro-reflecting sail increases in > momentum to compensate for the spacecraft's decrease in momentum, > and thereby ends up carrying all of the momentum from the beamed > power by the time the spacecraft has come to "rest". > > Consider a photon with momenergy [ p, p, 0 ] (that is, energy p, > momentum p in the x direction, no momentum in the y direction), > incident on a mirror with initial momenergy [ m, 0, 0 ] tilted at > an angle theta, such that when theta = 0 the mirror reflects the > photon straight back along its original path, and positive theta > means counterclockwise rotation of the mirror. After reflection, > the photon has momenergy > > [ p, -p * cos(2 * theta), -p * sin(2 * theta) ], > > and to conserve momenergy the mirror must then have momenergy > > [ m, p * (1 + cos(2 * theta)), p * sin(2 * theta) ]. > > (the total system momenergy remains [ m + p, p, 0 ]). > > You'll note that the expression (1 + cos(2 * theta)) is always > greater than or equal to 0. In other words, the x-component of > the mirror's momentum after reflection is always forward, or at > best nil. So you can steer by tilting the sail, but you can't > slow down. > > If you use multiple reflections, then you can analyze the > behavior simply by considering the final photon momentum after > the reflections. > > In the case of a double reflection that leaves the photons > travelling in the same direction they originally were (maybe > parallel to their original course) then there is _no_ net change > in spacecraft momentum. If you change the direction of the > photons, then you must _always_ leave them with a smaller > x-component of momentum than they originally had, and this > results in increased x-momentum for the spacecraft. You may be > able to decrease the efficiency of the sails as much as you want, > but you will never produce deceleration with multiple-reflection > schemes as long as the sails are attached to the spacecraft and > therefore tied to the spacecraft's momenergy. > > A really thorough treatment of multiple reflections would have to > consider both the finite speed of light and the finite speed of > propagation of changes in velocity through the spacecraft > structure; for very high rates of acceleration these would be > significant effects. > I think you have not completely understood my proposal. I am _not_ saying that the ship would slow down by this arrangement of sails, I'm only saying that the foreward momentum of the photons would be dumped into sideways momentum (which would then cancel out due to symetry) the photons would be absorbed and converted to electricity, then used to power a linear accelerator. All this rigamarole is to get around Timothy's valid objection that the foreward momentum of the recieved photons would exceed the momentum of the lineac if the antenna were not tilted. I readily admit that i lack the mathmatical tools to properly analyze this, I was hoping that someone else could do that part. But, The main point of the idea is valid, namely that by breaking up the sail/antenna into many conic sections, the foreward momentum of the absorbed photons can be dumped into the antenna's structure, and not into foreward acceleration of the "Asimov" From popserver Tue Nov 21 22:07:53 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9782" "Tue" "21" "November" "1995" "06:40:07" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "242" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA24233; Tue, 21 Nov 95 04:39:06 PST Received: by maroon.tc.umn.edu; Tue, 21 Nov 95 06:40:08 -0600 Reply-To: Kevin C Houston In-Reply-To: <199511151422.AA06167@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=us-ascii X-UIDL: 816991539.006 From: Kevin C Houston Sender: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 21 Nov 1995 06:40:07 -0600 (CST) To: Timothy From: Kevin H. Subject: Various On Wed, 15 Nov 1995, Timothy van der Linden wrote: > Subject : Photon energy > ReplyTo : Timothy > ReplyFrom: Kevin > > >now let's use that energy we absorbed (minus 20% for conversion losses, > >now E= 8 E+18) to accelerate some amount of material to allow us to slow > >down. to find out how much material (per second) we must eject, let's use > >the rocket equation first. the apparent mass Ma (as seen by the crew) of the > >exhaust is g * M /Ve * c where Ve is .9996 and g is 23.34 (10 m/s^2 for > >us, and 13.34 m/s^2 to counteract the photonic thrust) so Ma= 194.71 Kg/sec > >moving at .9996 of c. note that this is only 3.89 Kg out of the tanks so > >thus the rest mass of the exhaust is 3.89 Kg/sec. > > > >Now let's see how much energy it takes to accelerate 3.89 Kg to .9996 of c > >the energy will equal the kinetic energy of accelerating the mass to the > >required speed, plus the energy of the "mass increase" E=Ke + Re > >Ke=1/2 m v^2 = 1/2 *3.89* (.9996*c)^2 = 1.74 E+17 > >Re= m c^2 = (194.71 - 3.89) * c^2 = 1.71 E+19 > > > >total energy required = 1.73 E+19 > > < Some text left out> > > >Okay, Okay, I see your point (finally). so we can speed up, but we can't > >slow down even using beamed power. unless we use a retro reflecting ring > >sail, and that seems like such a waste > > I'm happy to hear this. Unfortunately your conclusion was based on wrong > calculations. I will explain here: > > You used: g * M /Ve * c but that formula is non relativistic. The right > formula would be: g * M /(Ve * c * gamma) > This gives the mass exhaust per second. That mass does not need to be > translated to 'out of the tanks'-mass. But thats what I used, granted I did it in two steps, but multipling the result of g * M / (Ve *C) by SQRT(1-Ve^2/C^2) is the same as your formula > > After that you use a strange and wrong method to calculate the needed energy. > The right formula for kinetic energy would be: E=m c^2 (gamma-1) > (You don't need to create the rest energy, that part is already onboard the > ship in the form of mass) > No, I'm not creating rest energy, I'm creating the relativistic energy. my energy formula (which may well be wrong) was broken into two parts: 1) a non-relativistic KE formula for getting the rest mass up to Ve KE=1/2 m (Ve*C)^2 2) a way to account for apparent mass increase (sorry steve, I know that grates on you, but it don't make sense to me any other way) by using E=mc^2 and may I point out that my answers were within 5% of the "correct" answers. not bad for a first guess. However, I will in the future use: KE=M * C^2 * (gamma - 1) where gamma=1/SQRT(1-Ve^2) Note, in my formulas Ve is expressed as a fraction of C anyway, so I don't have to divide by C^2 > Subject : The bathtub is flowing over (EUREKA) > > > >First, there is _no_ way to reduce the momentum imparted by the photons. > >However, we _can_ change the _direction_ of the thrust. > > NO and yes, you cannot change the initial size and direction of the photon > thrust, but you can (of course) choose the direction of the thrust when > transmitting a photon. > > In better words: > You should see the reflection of a photon as two steps, independant of each > other. > The first step is receiving the photon where momenum to your mirror is added > in the same direction as the photon CAME FROM. > The second step is transmitting(reflecting) the photon, hereby is the > momentum of the photon added in the opposite direction the photon GOES TO. > So if you shoot a photon from the negative x direction to a mirror which is > has 45 degree angle(on the x=y line) it first gets the momentum p in the x > direction and second the momentum p in the y direction. This makes a total > momentum of Sqrt(p^2+p^2)=Sqrt(2)*p in the xy direction. > > ^ > | y > | / | > ______|/ | > / +--- x > / > No, the momentum of absorbing the photon: cos (45) * p and the momentum of transmiting a photon: cos (45) * p adding them together would give you 2 cos(45)*p and since cos (45) = SQRT(2)/2, the total is: (drum roll please) Sqrt(2)*p Which of course is the same result as your formula, but for different reasons. and would not be the same for angles other than 45 Question: If a photon has a waveLENGTH of 21 cm, what's it's waveWIDTH? Hint: It ain't zero. > > > But now how do you capture the photons? You are talking about mirrors (sail) > all the time but not about capture. (I included a GIF-image of how I think > you would do that) No, _you_ keep talking mirrors all the time. I never once talked about reflecting the photons anywhere. BTW, I've never gotten one gif image to work. I can save 'em, and I can get them to my home machine, but when they get there, I get a "Not a vaild GIF file" when I try to display. And that includes a file that Kelly FTP'd me, so I know it's not my mail program. Maybe I'm just a lone IBM'er in a MAC group. any other IBM'ers here? Did you get the GIF's to work? let me know so's I can get working copies please. > I still don't know why you used an angle of 76.6, doing the calculation with > an angle of 85 degrees you need even less energy. Every time I worked out the formulas, (and I just did it with your equation for KE) I ended up with not enough energy if I used an angle of less than 76.6 degrees (photon thrust exceeds engine thrust) and too much left over energy if I used an angle much greater than 76.6 (engine thrust exceeds photon thrust) > You tried to trick the photons and thereby violated the preservation of > momentum: If you receive an amount of photons, all their momentum is > transferred to you. Yes, agreed. I received all of the photons Monmentum, but only cos(76.6) of it is in the direction of ships travel. > Once more, whatever ingenious construction you can think of, to receive a > certain amount of photons and use their energy, you ALWAYS get ALL their > momentum in the same direction as they went to. No, not true. Tilted surfaces receive all the momentum, but at an angle which is normal to backside of the surface. To : All From: Kevin Subject: Revised numbers using Timothy's Kinetic Energy formula: Velocity of exhaust: .99996 C (yes, this has changed also) gamma of exhaust 111.8045 Energy Beamed from Earth 2.08 E+19 Watts Energy after conversion 1.66 E+19 Watts (80% eff) angle of antenna: 76.6 cosine of angle : 0.360702 at this angle and energy, the photons impart a 10 m/s^2 foreward thrust so the ship's engine must impart a 20 m/s^2 backward's thrust. to accomplish this we need an exhaust rest mass of G*M/(Ve*C*gamma) which equals 1.49 Kg/sec out of the tanks getting this up to .99996 C will require M*C^2*(gamma-1) or 1.49E+19 Watts leaving 1.77 E+18 left over. more than enough energy to keep the crew alive. I'm still working on the heat balance, more when I finish To: All From: Kevin Re: Question on diodes (schottsky's) As you no doubt know, conversion from microwaves to elec power is achieved with diodes. I've been assuming that a diode on the antenna but not connected to a circuit is just sitting there, and the antenna will reflect. when the circuit is completed, the diode will convert the microwaves to elec with some heat left over, and the antenna wil absorb. is this correct? Kevin P.S. to Timothy: I can't speak for Steve, but yes, I do actually write these at 2:08 am or whatever time appears on the header. I often stay up late or get up early to write these. and of course, the time you see is the time I sent it, not the time I started, so you can subtract about two days for writing time ;) PPS to All: I heard a couple of good jokes: 1) How do a Mathamatician, a Physist, and an Engineer _prove_ all odd numbers are prime? The Mathamatician says: 3 is prime, 5 is prime, 7 is prime. That's three examples, the rest follows by induction. The Physicist says: 3 is prime, 5 is prime, 7 is prime, 9 is... experimental error, 11 is prime, 13 is prime .... The Engineer says: 3 is prime, 5 is prime, 7 is prime, 9 is close to being prime, and as we get into higher and higher numbers, the difference between the prime and non-prime portions is so small that it can be ignored. And the Technician says: 3 is prime, 5 is prime, 7 is prime, 9 is... Hey Joe, hand me hammer. second joke: The Mathamatician, Physicist, and Engineer were all at a conference (on prime numbers no less) and that night, a fire broke out in each room. The Engineer woke up, saw the fire, grabbed a bucket, and ran into the bathroom. he estimated the size of the fire, rate of spread and available oxygen, and drew that much water plus 10% to cover his errors. He ran back into the bedroom, poured 95% of the water onto the fire, checked that it was out, then poured the rest just to make sure, and went back to bed. The Physicist woke up, saw the fire, grabbed a bucket, and ran into the bathroom. he wrote down a few equations detailing the size of the fire, the rate of spread and the available oxygen, accounted for the ambient temperature and humidity of the air, as well as the heat of combustion of the materials that were burning, calculated the precise amount of water to put out the fire, drew that amount and ran back into the bedroom, poured the water on the fire, checked the results against the predicted results and went back to bed. The Mathamatician woke up, saw the fire, grabbed a bucket, and ran into the bathroom. he turned on the faucet, saw the water coming out. wrote down a few equations, proved a solution existed. and went back to bed. From popserver Tue Nov 21 22:08:52 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4889" "Tue" "21" "November" "1995" "21:31:53" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "131" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA19534; Tue, 21 Nov 95 12:31:28 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA00782 (5.67b/IDA-1.5 for ); Tue, 21 Nov 1995 21:31:46 +0100 Message-Id: <199511212031.AA00782@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 816991539.036 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 21 Nov 1995 21:31:53 +0100 ReplyFrom: Timothy ReplyTo : Kevin H. Subject : Sail >But thats what I used, granted I did it in two steps, but multipling the >result of g * M / (Ve *C) by SQRT(1-Ve^2/C^2) is the same as your formula Yes agreed, somehow I missed that. I derived the formula using relativistics from the start. It can be dangerous to use non-relativistic formulas and later subtitute relativistic ones! >However, I will in the future use: >KE=M * C^2 * (gamma - 1) >where >gamma=1/SQRT(1-Ve^2) Great, but I think Steve does not like them... :) >No, the momentum of absorbing the photon: cos (45) * p >and the momentum of transmiting a photon: cos (45) * p > >adding them together would give you 2 cos(45)*p >and since cos (45) = SQRT(2)/2, the total is: (drum roll please) > >Sqrt(2)*p > >Which of course is the same result as your formula, but for different >reasons. and would not be the same for angles other than 45 OK, let me rewrite this and tell me if you agree: incoming outgoing ray ray \ / \ / \ / a (\/ ------------------- mirror (sail?) || || \/ resulting momentum The ray reflects at an angle a, this gives the mirror a momentum of 2*p*SIN(a) where p the momentum of the incoming and outgoing photon (this assumes the mirror does not move). The (kinetic) energy gain of the mirror in this proces is 2*p*c*SIN(a) the other part of the energy of the photon is still in the outgoing ray. >Question: If a photon has a waveLENGTH of 21 cm, what's it's waveWIDTH? > >Hint: It ain't zero. waveWIDTH ? I've never heard of this, please explain this new phenomenon if relevant. >> But now how do you capture the photons? You are talking about mirrors (sail) >> all the time but not about capture. (I included a GIF-image of how I think >> you would do that) >No, _you_ keep talking mirrors all the time. I never once talked about >reflecting the photons anywhere. Then where is the conical section sail used for if it does not reflect? >BTW, I've never gotten one gif image to work. I can save 'em, and I can >get them to my home machine, but when they get there, I get a "Not a >vaild GIF file" when I try to display. And that includes a file that >Kelly FTP'd me, so I know it's not my mail program. Maybe I'm just a lone >IBM'er in a MAC group. any other IBM'ers here? Did you get the GIF's to >work? let me know so's I can get working copies please. It was a 2 color (1 bit) GIF image created with CorelDraw. Maybe that 1 bit thing is why it did not work. What image viewer do you use?. Anyway, I will put it on the web, use your web browser with the next URL: http://rugth10.th.rug.nl/~linden/ray.gif >> You tried to trick the photons and thereby violated the preservation of >> momentum: If you receive an amount of photons, all their momentum is >> transferred to you. > >Yes, agreed. I received all of the photons Monmentum, but only cos(76.6) >of it is in the direction of ships travel. I still think you forgot something, but also I still don't know how and where you receive the momentum. I think I don't understand the explaination in the first letter you wrote about this. >> Once more, whatever ingenious construction you can think of, to receive a >> certain amount of photons and use their energy, you ALWAYS get ALL their >> momentum in the same direction as they went to. > >No, not true. Tilted surfaces receive all the momentum, but at an angle >which is normal to backside of the surface. Ah, do I get it right if I think you mean that the sail absorbs the photons? And that you think that if the photons are absorbed at an angle the forward momentum is less than if the photons are absorbed perpendicular? If these last guesses are wrong please answer the lines above the last quotes. ReplyTo : Kevin ReplyFrom: Tim Subject : Question on diodes (schottsky's) >As you no doubt know, conversion from microwaves to elec power is >achieved with diodes. I only have a fague idea of how this works. A Skottky diode is just a fast diode, right? First of all do we really need direct current or can we make an alternating current work also? If you really create a direct current, how do you complete the current loop so that the antenna does not become positive or negative loaded. >I've been assuming that a diode on the antenna but >not connected to a circuit is just sitting there, and the antenna will >reflect. That's why I didn't get it the first time I guess. >When the circuit is completed, the diode will convert the >microwaves to elec with some heat left over, and the antenna wil absorb. >is this correct? When and why is the circuit completed? I know some things about electronics but how to use antennas to make a direct current from a wave. If someone is able to explain in an other way, I would be very happy. From popserver Wed Nov 22 01:11:49 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["4528" "Tue" "21" "November" "1995" "19:05:38" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "131" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA07314; Tue, 21 Nov 95 17:04:33 PST Received: by maroon.tc.umn.edu; Tue, 21 Nov 95 19:05:38 -0600 In-Reply-To: <199511212031.AA00782@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817002585.000 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 21 Nov 1995 19:05:38 -0600 (CST) To: Timothy From: Kevin > > >However, I will in the future use: > >KE=M * C^2 * (gamma - 1) > >where > >gamma=1/SQRT(1-Ve^2) > > Great, but I think Steve does not like them... :) arrgghh! will you two make up your mind! either figure it out, consult a prof. or a book or something. and when you do get it right, please tell me and I'll use that method. > > > >No, the momentum of absorbing the photon: cos (45) * p > >and the momentum of transmiting a photon: cos (45) * p > > > >adding them together would give you 2 cos(45)*p > >and since cos (45) = SQRT(2)/2, the total is: (drum roll please) > > > >Sqrt(2)*p > > > >Which of course is the same result as your formula, but for different > >reasons. and would not be the same for angles other than 45 > > OK, let me rewrite this and tell me if you agree: > > incoming outgoing > ray ray > \ / > \ / > \ / > a (\/ > ------------------- mirror (sail?) > || > || > \/ > resulting momentum > > The ray reflects at an angle a, this gives the mirror a momentum of > 2*p*SIN(a) where p the momentum of the incoming and outgoing photon (this > assumes the mirror does not move). > The (kinetic) energy gain of the mirror in this proces is 2*p*c*SIN(a) the > other part of the energy of the photon is still in the outgoing ray. > Okay, I see, it does give the same result for angles other than 45 degrees. but it's cos not sin. and now your drawing shows just what I'm saying... if the incoming ray (in your drawing) is from Sol, then the resulting momentum would not be in the direction of T.C. > >Question: If a photon has a waveLENGTH of 21 cm, what's it's waveWIDTH? > > > >Hint: It ain't zero. > > waveWIDTH ? I've never heard of this, please explain this new phenomenon if > relevant. > Not new at all, tbhe width of a EM wave is the same as it's length. That's why an absorbed photon gives a momentum normal to the absorbing surface. > >> But now how do you capture the photons? You are talking about mirrors (sail) > >> all the time but not about capture. (I included a GIF-image of how I think > >> you would do that) > > >No, _you_ keep talking mirrors all the time. I never once talked about > >reflecting the photons anywhere. > > Then where is the conical section sail used for if it does not reflect? > It reflects during the accel portion of the trip. During decell phase, the conical section is an antenna. and it absorbs. > >Yes, agreed. I received all of the photons Monmentum, but only cos(76.6) > >of it is in the direction of ships travel. > > I still think you forgot something, but also I still don't know how and > where you receive the momentum. I think I don't understand the explaination > in the first letter you wrote about this. > > Tilted surfaces receive all the momentum, but at an angle > >which is normal to backside of the surface. > > Ah, do I get it right if I think you mean that the sail absorbs the photons? > And that you think that if the photons are absorbed at an angle the forward > momentum is less than if the photons are absorbed perpendicular? Yes, That seems right. Let me try again. y (T.C.) ^ | | +---> x Note: the "real" thrust should be normal to the | surface, ascii graphics prevents this | (abs) means absorbed V -y (Sol) Exhaust /\ real +y-component || +y-component thrust | || | real \ | / / |~~| \ \ | /thrust \|/ / | | \ \|/ -x <-----/^(abs) / | C| \ (abs)^\------> +x component / | /a) | o| \ | \ component | | r| | | | e| | incoming incoming photon photon Also note, I've omitted cabling across the T.C. side and Soll side of the sail. This cabling mechanically transmitts the force from one side of the sail to the other. > > I only have a fague idea of how this works. A Skottky diode is just a fast ^^^^^ I'm not trying to flame you Tim, I think you meant "vague" and since you're not sure either, Let's wait to hear from someone who is. Kevin From popserver Wed Nov 22 01:32:02 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2706" "Tue" "21" "November" "1995" "17:28:52" "-0800" "Steve VanDevender" "stevev@efn.org" nil "73" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA08707; Tue, 21 Nov 95 17:26:54 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id RAA14622; Tue, 21 Nov 1995 17:28:52 -0800 Message-Id: <199511220128.RAA14622@tzadkiel.efn.org> In-Reply-To: References: <199511212031.AA00782@student.utwente.nl> X-UIDL: 817003798.000 From: Steve VanDevender To: Kevin C Houston Cc: Timothy van der Linden , KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 21 Nov 1995 17:28:52 -0800 Kevin C. Houston writes: > To: Timothy > From: Kevin > > >However, I will in the future use: > > >KE=M * C^2 * (gamma - 1) > > >where > > >gamma=1/SQRT(1-Ve^2) > > > > Great, but I think Steve does not like them... :) > > arrgghh! will you two make up your mind! either figure it out, consult > a prof. or a book or something. and when you do get it right, please > tell me and I'll use that method. I say that "relativistic mass increase" is a misnomer and that you are better off treating mass as invariant. > > OK, let me rewrite this and tell me if you agree: > > > > incoming outgoing > > ray ray > > \ / > > \ / > > \ / > > a (\/ > > ------------------- mirror (sail?) > > || > > || > > \/ > > resulting momentum > > > > The ray reflects at an angle a, this gives the mirror a momentum of > > 2*p*SIN(a) where p the momentum of the incoming and outgoing photon (this > > assumes the mirror does not move). > > The (kinetic) energy gain of the mirror in this proces is 2*p*c*SIN(a) the > > other part of the energy of the photon is still in the outgoing ray. > > Okay, I see, it does give the same result for angles other than 45 degrees. > but it's cos not sin. Timothy uses a different convention for the angle than I did. His math is correct using his convention. I was measuring a relative to normal of the mirror plane rather than relative to the surface. > Not new at all, tbhe width of a EM wave is the same as it's length. Huh? Why is this even relevant? > That's why an absorbed photon gives a momentum normal to the absorbing > surface. BZZZT! Thank you for playing. A reflected photon transfers momentum to a reflector normal to the reflecting surface. An absorbed photon transfers momentum in the direction and magnitude of the the photon's original momentum. This is the only consistent way to preserve conservation of momentum in both cases. Fundamental principle of relativistic mechanics: The momenergy (vector quantity of energy and momentum of a system) is conserved within the system through all interactions of the system components. If an absorbed photon only transferred momentum normal to the surface of the absorber, then the final momentum total for the system (photon and absorber) would _decrease_. This can't be true. You can't even weasel out of it by saying the momentum goes into extra heat or energy or something; momentum and energy are tallied in separate components. The photon energy goes into raising the heat of the absorber. The momentum goes into changing the velocity of the absorber. From popserver Wed Nov 22 20:46:56 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["2976" "Wed" "22" "November" "1995" "18:18:59" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199511221718.AA11651@student.utwente.nl>" "81" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA19266; Wed, 22 Nov 95 09:17:30 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA11651 (5.67b/IDA-1.5 for ); Wed, 22 Nov 1995 18:18:49 +0100 Message-Id: <199511221718.AA11651@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817073086.001 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Wed, 22 Nov 1995 18:18:59 +0100 ReplyTo : Steve and Kevin ReplyFrom: Timothy >I say that "relativistic mass increase" is a misnomer and that >you are better off treating mass as invariant. Both methods are valid to use. The difference is more a physical matter than a mathematical. I was used to working with the "wrong" formulas and Steve was used working with the "right" formulas. The so called "wrong" formulas look a bit more like the classic formulas so they may be easier to understand. Both methods are being taught at universities and both are valid. I've always looked at is as follows: When you move faster and faster, part of the energy is transformed into mass, the other part is used to get the extra momentum. Now I only wonder, does such a fast moving particle excert greater gravitation on a non-moving observer? Steve if the answer is yes, how do you explain that not using "relativistic mass increase"? >Timothy uses a different convention for the angle than I did. >His math is correct using his convention. I was measuring a >relative to normal of the mirror plane rather than relative to >the surface. Yeps, it seems I'm a bit odd, doing that. >A reflected photon transfers momentum to a reflector normal to >the reflecting surface. An absorbed photon transfers momentum in >the direction and magnitude of the the photon's original >momentum. This is the only consistent way to preserve >conservation of momentum in both cases. Yes, this is what I tried to explain from the start, but due to misunderstandings I was not able to get to the point earlier. >Fundamental principle of relativistic mechanics: The momenergy >(vector quantity of energy and momentum of a system) is conserved >within the system through all interactions of the system >components. Or as I wrote earlier: Once more, whatever ingenious construction you can think of, to receive a certain amount of photons and use their energy, you ALWAYS get ALL their momentum in the same direction as they went to. ReplyTo : Kevin ReplyFrom: Timothy Here are some answers to the remaining part of your letter: >> Ah, do I get it right if I think you mean that the sail absorbs the photons? >> And that you think that if the photons are absorbed at an angle the forward >> momentum is less than if the photons are absorbed perpendicular? > >Yes, That seems right. Let me try again. So I finally understand... (Now I wonder how you turn a perfectly reflecting sail in an perfect absorber) >> I only have a fague idea of how this works. A Skottky diode is just a fast > ^^^^^ >I'm not trying to flame you Tim, I think you meant "vague" >and since you're not sure either, Let's wait to hear from someone who is. I don't mind people telling me how to write better English. Since it is not my native language I'm almost certain to be doomed to make mistakes. To: Ric Hedman Writing long mails is OK, but to write 4 lines and quote the other 250 lines seems a bit too much. Timothy From popserver Sat Nov 25 06:44:05 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["5191" "Fri" "24" "November" "1995" "21:05:06" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951124210503_115665323@emout04.mail.aol.com>" "121" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA18135; Fri, 24 Nov 95 18:05:09 PST Received: by emout04.mail.aol.com (8.6.12/8.6.12) id VAA07186; Fri, 24 Nov 1995 21:05:06 -0500 Message-Id: <951124210503_115665323@emout04.mail.aol.com> X-UIDL: 817281638.011 From: KellySt@aol.com To: stevev@efn.org, hous0042@maroon.tc.umn.edu Cc: T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu Subject: Re: Engineering Newsletter Date: Fri, 24 Nov 1995 21:05:06 -0500 >> A reflected photon transfers momentum to a reflector normal to >> the reflecting surface. An absorbed photon transfers >> momentum in the direction and magnitude of the the >> photon's original momentum. This is the only consistent >> way to preserve conservation of momentum in both cases. --- >> If an absorbed photon only transferred momentum normal >> to the surface of the absorber, then the final momentum >> total for the system (photon and absorber) would >> _decrease_. This can't be true. You can't even weasel >> out of it by saying the momentum goes into extra heat >> or energy or something; momentum and energy >> are tallied in separate components. The photon energy >> goes into raising the heat of the absorber. The momentum >> goes into changing the velocity of the absorber. The papers I've seen on on solar sails seem to disagree with you. RThey propose angling the sial to alter the thrust vector. Which would be impossible if the momenum transfer was always in the direction of the photons origional vector. Come to think of it all solar sailing would be impossible, since the purpose is alway to add or subtract velocity perpendicular to the solar light vector. Also it would be rather strange given thatthe photon has changed its course and mometum vector to one crossing the ship and beam vectors. Since its new course has an added lateral vector, there must have been a coresponding lateral vector componenect in the reflection of the sail. I have a lot of problem bying the idea that the light bouncing off a sail doesn't lose energy proportional to the kinetic or heat energy gain of the ship. Th power has to be coming from somewhere. > > On Wed, 15 Nov 1995 KellySt@aol.com wrote: > > > > > I still have questions about momentum transfer vs power absorbsion. This > > > neat conversion of absorbed power and momentum bothers me. I would think > > > that converting the power would use up the energy that would generate the > > > thrust. Maybe I'm confused? > > > > > > > Not at all, if you reflect, you get twice the momentum that you'd get if > > you absorbed. so there is no violation of energy conservation. This implies that the power of the beam is half the momentum of the beam. But if the beam is reflected, and gives up twice the momenum, it would have exausted all its power. If its then reflected again, it would lose more. This doesn't work. So: What percentage of the beam energy is lost in a reflection? (If this % is small, the the remainder might be enough to power the ships drive.) KS >> Durring the decel phase. The outer sails are trimed to reflect their KS >> energy inward toward frount of the inner sails. The inner sails are trimed KS >> to reflect the energy hiting their back inward toward other sails or KS >> dumping it. But this foward and outward thrust, serves to support them KS >> against backward and inward thrurst from the energy pouring inward and KS >> back from the outer sails onto the frount of the inner sails. The frount KS >> of the inner sails have the rectenna arrays. Which absorb and convert the KS >> microwaves. > KS >> Good news. KS >> The sails have max reflectivity durring accel phase. > KS >> Only the inner sail array needs the more complecated rectenna and power KS >> conversion/transmition/cooling equipment. (The outer segments are just KS >> wire mesh.) So servicing and costs can be minimized. > KS >> Bad news KS >> The expensive power converters are going to be face first into the inter KS >> stellar medium, and they are going to be operating at much higher power KS >> densities. Cooling is going to be much harder. > >1) about power converters (schottsky diodes) being > face first into the "wind" we are going to need a lot of > tension wires to keep the antenna from blowing apart, so >if they were on the front, they would effectivly shield the diodes. Not unless the wires became a wall. > 2) about cooling, angling the antennas requires more surface > area, allowing for _smaller_ power densities, and more > surface to radiate the heat. But if you reflect the beam inward, it will be concentrated to far higher power levels. The angle and demensions of the antenna isn't important. only the power density on the converter array. > KS >> Weird thought. Am I right that microwaves can impart thier momentum on KS >> ions directly? Could you channel the power via waveguides, and feed the KS >> reaction mass into the power stream and get it to accelerate the plasma KS >> directly? I can't remenber it clearly, but I think their is some such KS >> mechanism. If so, you could avoid the heating problems of the power KS >> conversion step. > Agreed, this should be looked into. Not sure if this is possible with > microwaves, I'm having difficulty seeing how the microwaves could be > reflected into the reaction chamber without the inner sail elements > getting in the way of the outer ones. but if it could be made to work, > it would solve the heat problem neatly. The sails could be kept out of the way. Also the use of waveguides would be usefull for the inner systems. Kelly Starks From popserver Sat Nov 25 07:49:53 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5251" "Fri" "24" "November" "1995" "23:47:54" "-0800" "Steve VanDevender" "stevev@efn.org" nil "107" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA27800; Fri, 24 Nov 95 23:45:00 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id XAA05957; Fri, 24 Nov 1995 23:47:54 -0800 Message-Id: <199511250747.XAA05957@tzadkiel.efn.org> In-Reply-To: <951124210503_115665323@emout04.mail.aol.com> References: <951124210503_115665323@emout04.mail.aol.com> X-UIDL: 817285608.000 From: Steve VanDevender To: KellySt@aol.com Cc: stevev@efn.org, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu Subject: Re: Engineering Newsletter Date: Fri, 24 Nov 1995 23:47:54 -0800 KellySt@aol.com writes: > The papers I've seen on on solar sails seem to disagree with > you. RThey propose angling the sial to alter the thrust > vector. Which would be impossible if the momenum transfer was > always in the direction of the photons origional vector. You don't seem to have read what I wrote, so I'll repeat it below. > >> A reflected photon transfers momentum to a reflector normal to > >> the reflecting surface. This in no way contradicts your understanding. If you tilt a sail, you get a sideways thrust on the sail. The momentum transfer is in the direction against the normal (the perpendicular to the surface) of the sail. However, absorbing a photon is different. In this case conservation of momentum requires that all of the photon's momentum and energy be transferred into the absorbing object. What I was objecting to earlier was Kevin's bald assertion that an absorbed photon adds momentum only relative to the normal of the absorbing surface, apparently because he did not properly analyze the behavior of reflection. You can think of reflection as a two-step process: absorption and re-emission. Momentum is transferred equally (as required by conservation of momentum) in each step. Kevin's mistake seemed to be in his calculation of the quantity of momentum transferred in each step, based on the total momentum transferred between the time before absorption and after re-emission. When a photon is absorbed, all of its energy is transferred into the absorber, and all of its momentum (not just some, as Kevin thought). If the photon was absorbed by a reflector, then it is instantly re-emitted, and the emitted photon has the same magnitude of energy and momentum as the original, but the momentum is in a different direction, and the reflector gets a new momentum component to compensate. The vector sum of the photon momenta before and after the reflection is the negative of the momentum transferred to the reflector, but the momentum transfer in each stage is not just half of this resultant vector. For an instant, the reflector speeds up the same way it would if it was never planning to re-emit the photon; an instant later it is accelerated in the direction opposite the emitted photon. > Come to think of it all solar sailing would be impossible, > since the purpose is alway to add or subtract velocity > perpendicular to the solar light vector. Also it would be > rather strange given thatthe photon has changed its course and > mometum vector to one crossing the ship and beam vectors. > Since its new course has an added lateral vector, there must > have been a coresponding lateral vector componenect in the > reflection of the sail. Light sailing would be useless if you couldn't get velocity components in other directions, say to put yourself in an orbit. Fortunately light sails don't work the way you think they do. In fact, your statement here contradicts your statement above -- either tilted light sails produce sideways thrust or they don't. To get velocity away from the star in the direction of light emitted from the star, aim your light sail to reflect light directly back at the star. To get velocity towards the star, turn your light sail sideways or furl it completely, and let the star's gravity accelerate you. There isn't a way to use the sail to accelerate yourself towards the star any faster than the star's gravity would accelerate you, though. Tilt the sail, and you get an additional velocity component perpendicular to the light emitted from the star. You are right, even though you don't want to believe yourself. > I have a lot of problem bying the idea that the light bouncing > off a sail doesn't lose energy proportional to the kinetic or > heat energy gain of the ship. Th power has to be coming from > somewhere. If the sail is reflective to the incident photon, then the photon doesn't lose energy as a result of reflection. The ship changes velocity because the photon changes direction. That's where the "power" comes from. If you don't buy conservation of momentum and energy, you won't get very far in physics. Here's an interesting thought experiment that I don't remember posting to the Starship Design forum, but that some of you may have seen since I do remember mailing it to somebody. You have two optically flat perfectly reflective mirrors (purchased from the same physics supply store where you get frictionless surfaces and other gedankenexperiment supplies). You also have a very powerful laser capable of emitting a short but extremely bright laser pulse, with sufficient momentum that the pulse can accelerate these mirrors measurably. Set up the two mirrors parallel to each other and facing each other, such that light can reflect between the mirrors indefinitely. Place the laser between them, and have it emit a light pulse aimed to reflect between the two mirrors; remove the laser immediately so that the light does not strike it but instead reflects between the two mirrors. What happens to the mirrors? What happens to the light pulse? An answer describing the limit state of the mirrors and light pulse is acceptable; you don't have to perform a step-by-step analysis of each reflection. From popserver Sat Nov 25 09:05:26 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4055" "Sat" "25" "November" "1995" "01:02:48" "-0800" "Steve VanDevender" "stevev@efn.org" nil "83" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA00273; Sat, 25 Nov 95 00:59:52 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id BAA06131; Sat, 25 Nov 1995 01:02:48 -0800 Message-Id: <199511250902.BAA06131@tzadkiel.efn.org> In-Reply-To: <199511221718.AA11651@student.utwente.nl> References: <199511221718.AA11651@student.utwente.nl> X-UIDL: 817290141.000 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sat, 25 Nov 1995 01:02:48 -0800 Timothy van der Linden writes: > ReplyTo : Steve and Kevin > ReplyFrom: Timothy > > >I say that "relativistic mass increase" is a misnomer and that > >you are better off treating mass as invariant. > > Both methods are valid to use. The difference is more a physical matter than > a mathematical. I was used to working with the "wrong" formulas and Steve > was used working with the "right" formulas. > The so called "wrong" formulas look a bit more like the classic formulas so > they may be easier to understand. > > Both methods are being taught at universities and both are valid. I think we'd both agree that, for example, p(v) = m * v / sqrt(1 - v^2). What I have learned to be suspicious of is interpreting this as (m/sqrt(1 - v^2)) * v, as if the mass somehow increases with velocity. What I find to be a more intuitive and less misleading interpretation is that mass is invariant (m^2 = E^2 - p^2) but that energy and momentum can increase without limit as the moving object accelerates. When doing more elaborate kinematics problems it's also easier to just keep track of the conserved E and p components, then sort out the resultant masses of the reaction products. Often in math there is more than one way to the right answer. I happen to find that concentrating on conservation of energy and momentum and keeping track of invariant quantities makes it easier to get the right answer and to prove that it's right. If you can do it the "wrong" way, get the right answer, and prove that it's right, then fine. > I've always looked at is as follows: When you move faster and faster, part > of the energy is transformed into mass, the other part is used to get the > extra momentum. I used to look at it this way, but Taylor and Wheeler talked me out of it (see chapter 8 of _Spacetime Physics_ for a lengthy, careful discussion on "Use and Abuse of the Concept of Mass"). The problem here is that relative velocity or acceleration do not cause any fundamental changes in the structure of the moving object. Where is this extra mass? If it's really stashed on the ship somewhere then the people on the ship could measure it. But they don't feel the ship getting heavier or see any increase in the mass of the ship in their frame. You also seem to be falling into the same trap that Kelly did earlier, in not treating energy and momentum as separate components. Most of the counterintuitive results of relativistic kinematics problems come from failing to understand that the conserved quantity in a reaction is a _vector_ quantity, and that the magnitude of that vector is calculated using Lorentz rather than Euclidean geometry. Taylor and Wheeler's wisdom on the subject is that the definition of mass is sqrt(E^2 - p^2); then every observer sees the same mass for the same object, no matter what their relative motion. The quick treatment in many physics texts is that mass is sort of like E, but they do a lot of tapdancing to keep everything consistent. This appears to be motivated by trying explain the famous "E = m * c^2", which turns out to be a lot less profound an observation than some of the other implications of relativistic physics. Taylor and Wheeler look at "E = m * c^2" as a mere matter of unit conversion; it's only really true if you are at rest relative to the mass in question, and they consider the use of Lorentz geometry for spacetime and invariance of spacetime interval as more fundamental and revealing concepts. > Now I only wonder, does such a fast moving particle excert greater > gravitation on a non-moving observer? This I can't answer with certainty. Offhand, I'd say "no." If the particle's mass doesn't change, then how could its gravitation change? > Steve if the answer is yes, how do you explain that not using "relativistic > mass increase"? If, on the other hand, a moving object did exert greater gravitation than a stationary object of the same mass, I'd probably be looking for a relation to a quantity that did change, like the object's total energy. From popserver Sun Nov 26 00:47:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["471" "Sat" "25" "November" "1995" "16:30:23" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "19" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA19362; Sat, 25 Nov 95 14:28:51 PST Received: by maroon.tc.umn.edu; Sat, 25 Nov 95 16:30:23 -0600 In-Reply-To: <199511250902.BAA06131@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817346679.003 From: Kevin C Houston To: Steve VanDevender Cc: Timothy van der Linden , KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 25 Nov 1995 16:30:23 -0600 (CST) To: all nitpickers From: A nit(wit) who is tired of getting picked on. ;) see my web page http://www.umn.edu/nlhome/m056/hous0042/asimov.html for an idea that is consistant with Steve and Timothy's objections. i.e. reflection transferrs momentum to the normal, and absorbtion transfers momentum in the direction of the photons original vector. Advance billing: it is _still_ possible to cancel the momentum within the structure of the antenna/sail . HA! Kevin From popserver Sun Nov 26 00:48:01 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["5281" "Sun" "26" "November" "1995" "00:51:51" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199511252351.AA19695@student.utwente.nl>" "125" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA21932; Sat, 25 Nov 95 15:49:42 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA19695 (5.67b/IDA-1.5 for ); Sun, 26 Nov 1995 00:51:43 +0100 Message-Id: <199511252351.AA19695@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817346679.008 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sun, 26 Nov 1995 00:51:51 +0100 ReplyTo : Kevin and Kelly ReplyFrom : Timothy Subject : Infinite energy? > > I have a lot of problem bying the idea that the light bouncing > > off a sail doesn't lose energy proportional to the kinetic or > > heat energy gain of the ship. Th power has to be coming from > > somewhere. > >If the sail is reflective to the incident photon, then the photon >doesn't lose energy as a result of reflection. The ship changes >velocity because the photon changes direction. That's where the >"power" comes from. I think I can't agree with that Steve, when the photon enters the first stage of the reflection, i.e. absorption, it adds some momentum to the ship. So the velocity of the ship increases. Now we enter the second stage of reflection, re-transmission. Relative to the ship the outgoing wavelength of the photon is the same as the incoming photon (because of invariance). But the observer at rest sees that that transmitted photon has dopplershifted (nice verb) and thus lost some energy. This is the same principle the police uses to measure speeding cars with radar. >What happens to the mirrors? What happens to the light pulse? >An answer describing the limit state of the mirrors and light >pulse is acceptable; you don't have to perform a step-by-step >analysis of each reflection. Assuming these mirrors have mass, they indeed will get some velocity that correspondends to the same momentum as the photon. By each reflection the photon will loose some momentum and lower its wavelength. ReplyTo : Kelly ReplyFrom : Timothy >I agree that we are stuck without a new power source. Kevins microwave >system or my Externally fueled system are at best theoretical possibilities, >with no real credible way to build them. Externally fueled did that mean scooping? I'm not sure anymore, please tell me if my assumption is right. ReplyTo : Steve ReplyFrom: Timothy Subject : Relativistic mass increase >>>I say that "relativistic mass increase" is a misnomer and that >>>you are better off treating mass as invariant. >> I've always looked at is as follows: When you move faster and faster, part >> of the energy is transformed into mass, the other part is used to get the >> extra momentum. > >I used to look at it this way, but Taylor and Wheeler talked me >out of it (see chapter 8 of _Spacetime Physics_ for a lengthy, >careful discussion on "Use and Abuse of the Concept of Mass"). >The problem here is that relative velocity or acceleration do not >cause any fundamental changes in the structure of the moving >object. Where is this extra mass? If it's really stashed on the >ship somewhere then the people on the ship could measure it. But >they don't feel the ship getting heavier or see any increase in >the mass of the ship in their frame. I wrote it wrong the first time, indeed then the mass must be somewhere on the ship. But look at it this way: When an object starts moving it deforms space-time in such a way that the object looks heavier to the outside world and the other way around, i.e. the object "notices" the outside world to be heavier. This means that locally no mass increase is measured, for the same reason that locally no length contraction or time dilation is measured. >You also seem to be falling into the same trap that Kelly did >earlier, in not treating energy and momentum as separate >components. Most of the counterintuitive results of relativistic >kinematics problems come from failing to understand that the >conserved quantity in a reaction is a _vector_ quantity, and that >the magnitude of that vector is calculated using Lorentz rather >than Euclidean geometry. I still don't see the trap where I fell in. You say that I should treat momentum and energy as seperate components. But I don't see how/where I treated them as one quantity. >Taylor and Wheeler's wisdom on the subject is that the definition >of mass is sqrt(E^2 - p^2); then every observer sees the same >mass for the same object, no matter what their relative motion. How do you measure E and p? E seems to be relativistic mass and p relativistic momentum. (E=gamma*m_rest p=gamma*m_rest*v) I would measure the perceived relativistic mass and the relative velocity. As far as I can see, doing that all observers will also agree about the rest mass. >> Now I only wonder, does such a fast moving particle excert greater >> gravitation on a non-moving observer? > >This I can't answer with certainty. Offhand, I'd say "no." If >the particle's mass doesn't change, then how could its >gravitation change? I don't know the answer for certain either, but when making the link with length contraction and time dilation I would say that indeed a bigger mass is measured. >> Steve if the answer is yes, how do you explain that not using "relativistic >> mass increase"? > >If, on the other hand, a moving object did exert greater >gravitation than a stationary object of the same mass, I'd >probably be looking for a relation to a quantity that did change, >like the object's total energy. So that would mean that some of the change in energy is change of gravitational energy, from which I would conclude that it comes from extra mass (or bending of space time). Is it this translation of energy to mass that gives the trouble? From popserver Sun Nov 26 01:13:12 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1344" "Sat" "25" "November" "1995" "17:08:10" "-0800" "Steve VanDevender" "stevev@efn.org" nil "32" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA25004; Sat, 25 Nov 95 17:05:08 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id RAA08463; Sat, 25 Nov 1995 17:08:10 -0800 Message-Id: <199511260108.RAA08463@tzadkiel.efn.org> In-Reply-To: References: <199511250902.BAA06131@tzadkiel.efn.org> X-UIDL: 817348202.000 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , Timothy van der Linden , KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 25 Nov 1995 17:08:10 -0800 Kevin C. Houston writes: > To: all nitpickers > From: A nit(wit) who is tired of getting picked on. ;) Sorry, but conservation of energy and momentum are too fundamental to ignore. If you can't follow those rules then you may as well give up and design a warp drive, since you're throwing out the laws of physics anyway. > see my web page > http://www.umn.edu/nlhome/m056/hous0042/asimov.html > for an idea that is consistant with Steve and Timothy's objections. > > i.e. reflection transferrs momentum to the normal, and absorbtion > transfers momentum in the direction of the photons original vector. > > Advance billing: it is _still_ possible to cancel the momentum within the > structure of the antenna/sail . > > HA! We'll see. You must either absorb the photon and thereby absorb its momentum, or reflect the photon and get momentum to balance the change in direction of the photon. The only way to not get any momentum change is to either not interact with the photon or reflect it so as to leave it travelling in the same direction it came with the same energy. If the system consisting of the photon beam and the spaceship plus sail assembly doesn't have the same momentum after the interaction as before, then you'll have to go back to the drawing board. Perhaps after a brief refresher course in physics. From popserver Sun Nov 26 02:03:31 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2224" "Sun" "26" "November" "1995" "02:59:48" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "70" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA26658; Sat, 25 Nov 95 17:57:27 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA23853 (5.67b/IDA-1.5 for ); Sun, 26 Nov 1995 02:59:44 +0100 Message-Id: <199511260159.AA23853@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817351221.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sun, 26 Nov 1995 02:59:48 +0100 ReplyTo : The Nitwit ReplyFrom : Nitpicker Timothy Hi Steve, I'm sorry to have frustrated you. The reason I'm doing that is because you are always finding these wonderful solutions and I can't stand that. :) No, not really of course, but it is really difficult, as we all know by now, to find a method to harnas these amounts of energy. I guess, if there was a easy and cheap way we would have found it by now. We all are hoping to find some ingenious way to get around all the problems at once, so all solutions are welcome. But also there is a great possibility that these solutions will fail. The only thing I can write is, let the new ideas come and try to explain why you think they work. Before you read any further I have to warn you :) TAKE SOME VALIUM TABLETS AND TRY TO RELAX... >see my web page >http://www.umn.edu/nlhome/m056/hous0042/asimov.html >for an idea that is consistant with Steve and Timothy's objections. I almost dare not saying it but, how accurate is your calculator? Let me recalculate the values of the various components: a=55.47 m/s^2 (purple) b=27.73 m/s^2 (red) Purple x-comp = a sin( 21) = 19.88 (you got 51.62) Purple y-comp = a cos( 21) = 51.79 (you got 20.3023) Red x-comp = b cos(-48) = -18.55 (you got -18.9) Red y-comp = b sin(-48) = -20.61 (you got -20.3021) I checked all cos and sin formulas in the drawing and all seem to be OK, the only things that are wrong are the final decimal numbers. If you now sum the several components: x=19.88-18.55=1.33 y=51.79-20.61=31.18 (This value is too high to compensate) (You wrote the formulas where you calculated the accelerations wrong but the answers seemed right) If you think other angles would make your system work, I still am certain it won't work. If you want to give it a try here are more general formulas: t is the angle for which you took 21 a=2b (reflected momentum is twice the absorbed momentum) remember t is between 0 and 90 Px=2b sin(t) Py=2b cos(t) Rx=b cos(-2t) Ry=b sin(-2t) x=Px+Rx=2b sin(t) + b cos(-2t) y=Py+Ry=2b cos(t) + b sin(-2t) only t=90 will make y equal to zero, but t=90 means the light goes straight on, whithout touching the mirror or absorber. Good luck, Timothy From popserver Sun Nov 26 02:53:50 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["1944" "Sat" "25" "November" "1995" "20:46:38" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "50" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA28253; Sat, 25 Nov 95 18:45:00 PST Received: by maroon.tc.umn.edu; Sat, 25 Nov 95 20:46:38 -0600 In-Reply-To: <199511260108.RAA08463@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817354240.000 From: Kevin C Houston To: Steve VanDevender Cc: Steve VanDevender , Timothy van der Linden , KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 25 Nov 1995 20:46:38 -0600 (CST) On Sat, 25 Nov 1995, Steve VanDevender wrote: > Kevin C. Houston writes: > > To: all nitpickers > > From: A nit(wit) who is tired of getting picked on. ;) > > Sorry, but conservation of energy and momentum are too > fundamental to ignore. If you can't follow those rules then you > may as well give up and design a warp drive, since you're > throwing out the laws of physics anyway. Would if I could, but I can't, so I won't. > > > see my web page > > http://www.umn.edu/nlhome/m056/hous0042/asimov.html > > for an idea that is consistant with Steve and Timothy's objections. > > > > i.e. reflection transferrs momentum to the normal, and absorbtion > > transfers momentum in the direction of the photons original vector. > > > > Advance billing: it is _still_ possible to cancel the momentum within the > > structure of the antenna/sail . > > > > HA! > > We'll see. You must either absorb the photon and thereby absorb > its momentum, or reflect the photon and get momentum to balance > the change in direction of the photon. The only way to not get > any momentum change is to either not interact with the photon or > reflect it so as to leave it travelling in the same direction it > came with the same energy. > no, first the photon is reflected at an angle, this dumps some of the momentum into the perpendicular directionthe photon leaves the first sail element (reflection) and is absorbed in the second, inner element. as far as that element is concerned, the photon came from the _front_ of the ship. > If the system consisting of the photon beam and the spaceship > plus sail assembly doesn't have the same momentum after the > interaction as before, then you'll have to go back to the drawing > board. Perhaps after a brief refresher course in physics. > it does have the same momentum, just that some of that momentum has been made to cancel out. equal but opposite momentums cancel out From popserver Sun Nov 26 02:53:52 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7812" "Sat" "25" "November" "1995" "18:48:43" "-0800" "Steve VanDevender" "stevev@efn.org" nil "162" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA28288; Sat, 25 Nov 95 18:45:40 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id SAA08671; Sat, 25 Nov 1995 18:48:43 -0800 Message-Id: <199511260248.SAA08671@tzadkiel.efn.org> In-Reply-To: <199511252351.AA19695@student.utwente.nl> References: <199511252351.AA19695@student.utwente.nl> X-UIDL: 817354240.001 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sat, 25 Nov 1995 18:48:43 -0800 Timothy van der Linden writes: > > > I have a lot of problem bying the idea that the light bouncing > > > off a sail doesn't lose energy proportional to the kinetic or > > > heat energy gain of the ship. Th power has to be coming from > > > somewhere. > > > >If the sail is reflective to the incident photon, then the photon > >doesn't lose energy as a result of reflection. The ship changes > >velocity because the photon changes direction. That's where the > >"power" comes from. > > I think I can't agree with that Steve, when the photon enters the first > stage of the reflection, i.e. absorption, it adds some momentum to the ship. > So the velocity of the ship increases. Now we enter the second stage of > reflection, re-transmission. Relative to the ship the outgoing wavelength of > the photon is the same as the incoming photon (because of invariance). But > the observer at rest sees that that transmitted photon has dopplershifted > (nice verb) and thus lost some energy. > > This is the same principle the police uses to measure speeding cars with radar. And I don't disagree with that analysis; it's correct in a frame where the ship is moving. In that frame, the photon has more energy and momentum, and while it changes momentum by the same amount as in the frame where the ship is "stationary", this necessarily results in a different-looking scenario. > >What happens to the mirrors? What happens to the light pulse? > >An answer describing the limit state of the mirrors and light > >pulse is acceptable; you don't have to perform a step-by-step > >analysis of each reflection. > > Assuming these mirrors have mass, they indeed will get some velocity that > correspondends to the same momentum as the photon. By each reflection the > photon will loose some momentum and lower its wavelength. This is exactly the analysis I came up with. In the limit the mirrors carry the momentum of the light pulse, and the light pulse fades to nothing. > >> I've always looked at is as follows: When you move faster and faster, part > >> of the energy is transformed into mass, the other part is used to get the > >> extra momentum. > > > >I used to look at it this way, but Taylor and Wheeler talked me > >out of it (see chapter 8 of _Spacetime Physics_ for a lengthy, > >careful discussion on "Use and Abuse of the Concept of Mass"). > >The problem here is that relative velocity or acceleration do not > >cause any fundamental changes in the structure of the moving > >object. Where is this extra mass? If it's really stashed on the > >ship somewhere then the people on the ship could measure it. But > >they don't feel the ship getting heavier or see any increase in > >the mass of the ship in their frame. > > I wrote it wrong the first time, indeed then the mass must be somewhere on > the ship. But look at it this way: When an object starts moving it deforms > space-time in such a way that the object looks heavier to the outside world > and the other way around, i.e. the object "notices" the outside world to be > heavier. > This means that locally no mass increase is measured, for the same reason > that locally no length contraction or time dilation is measured. Taylor and Wheeler say it better than I can. Their approach is based on years of teaching special relativity to new students, which is why I give it credence. So, to quote Taylor and Wheeler: Q: If the factor c^2 is not the central feature of the relationship between mass and energy, what _is_ central? A: The distinction between mass and energy is this: Mass is the magnitude of the momenergy 4-vector and energy is the time component of the same vector. Any feature of this discussion that emphasizes this contrast is an aid to understanding. Any slurring of terminology that obscures this distinction is a potential source of error or confusion. Q: Is the mass of a moving object greater than the mass of the same object at rest? A: No. It is the same whether the object is at rest or in motion; the same in all frames. To explain some of their terminology: Taylor and Wheeler teach relativistic kinematics using the notion of "momenergy". Since energy is conserved and the vector quantity of momentum is conserved in a system, they express the entire state of an object or system using a 4-vector that combines both quantities, which they call a "momenergy vector". An object's state of motion can be expressed as a vector of the form [ E px py pz ], where E is the object's energy and [ px py pz ] are the components of the object's momentum. Since vectors are normally added component by component, adding momenergy vectors preserves the conservation of the individual components. The other notion that they introduce at the very beginning of the book is that relativistic spacetime is non-Euclidean, even in special relativity. A vector of the form [ t x y z ] is defined to have magnitude sqrt(t^2 - x^2 - y^2 - z^2), which results in non-zero vectors that have magnitude zero (or even imaginary magnitude). The magnitude of a momenergy vector is exactly the mass of the system described by that vector. The only time that mass is equivalent to energy is when momentum is zero, or in a frame in which the object in question is at rest. > >Taylor and Wheeler's wisdom on the subject is that the definition > >of mass is sqrt(E^2 - p^2); then every observer sees the same > >mass for the same object, no matter what their relative motion. > > How do you measure E and p? E seems to be relativistic mass and p > relativistic momentum. (E=gamma*m_rest p=gamma*m_rest*v) > I would measure the perceived relativistic mass and the relative velocity. > As far as I can see, doing that all observers will also agree about the rest > mass. Another quote from Taylor and Wheeler: Q: In order to make this point clear, should we call invariant mass of a particle rest mass? A: That is what we called it in the first edition of this book. But a thoughtful student pointed out that the phrase "rest mass" is also subject to misunderstanding: What happens to the "rest mass" of a particle when the particle moves? In reality mass is mass is mass. Mass has the same value in all frames, is invariant, no matter how the particle moves. [Galileo: "In questions of science the authority of a thousand is not worth the humble reasoning of a single individual."] The way I was taught to measure mass is as sqrt(E^2 - p^2). So the mass of a particle with energy E = gamma * m_rest and momentum p = gamma * m_rest * v (where v is a vector) is m^2 = E^2 - p^2 = gamma^2 * m_rest^2 - gamma^2 * m_rest^2 * abs(v)^2 = gamma^2 * m_rest^2 * (1 - abs(v)^2) = m_rest^2 (gamma is 1/sqrt(1 - abs(v)^2)). So no matter how the particle moves it has the same mass. Mass is not energy. What you call "relativistic mass" I call energy; what I call "mass" you seem to want to call "rest mass", yet the quantity "mass" that I am using doesn't vary with motion. > >If, on the other hand, a moving object did exert greater > >gravitation than a stationary object of the same mass, I'd > >probably be looking for a relation to a quantity that did change, > >like the object's total energy. > > So that would mean that some of the change in energy is change of > gravitational energy, from which I would conclude that it comes from extra > mass (or bending of space time). First you have to convince me that a moving object really does exert more gravitational force. > Is it this translation of energy to mass that gives the trouble? It is that my studies of relativistic kinematics do not allow for the treatment of energy and mass as identical quantities. From popserver Sun Nov 26 03:19:04 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2340" "Sat" "25" "November" "1995" "21:16:30" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "61" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA29217; Sat, 25 Nov 95 19:14:58 PST Received: by maroon.tc.umn.edu; Sat, 25 Nov 95 21:16:31 -0600 In-Reply-To: <199511260159.AA23853@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817355753.000 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 25 Nov 1995 21:16:30 -0600 (CST) On Sun, 26 Nov 1995, Timothy van der Linden wrote: > ReplyTo : The Nitwit BTW, in english, a nitwit is a stupid person. (someone with the brains of a nit ) in so naming myself, I admit my previous errors > ReplyFrom : Nitpicker Timothy > > Hi Steve, I'm sorry to have frustrated you. actually, it's Kevin, I know it can be confusing when three or more people are engaged in debate, but try to keep us straight. It's not nice to insult Steve's intelligence like that. > The reason I'm doing that is because you are always finding these wonderful > solutions and I can't stand that. :) No, not really of course, but it is > really difficult, as we all know by now, to find a method to harnas these > amounts of energy. I guess, if there was a easy and cheap way we would have > found it by now. We all are hoping to find some ingenious way to get around > all the problems at once, so all solutions are welcome. But also there is a > great possibility that these solutions will fail. > > The only thing I can write is, let the new ideas come and try to explain why > you think they work. > > Before you read any further I have to warn you :) > > TAKE SOME VALIUM TABLETS AND TRY TO RELAX... > > >see my web page > >http://www.umn.edu/nlhome/m056/hous0042/asimov.html > >for an idea that is consistant with Steve and Timothy's objections. > > I almost dare not saying it but, how accurate is your calculator? > not very, considering i lost it (or it was stolen), I've been using EXCEL for my calculations, also, I rounded the actual angle of the sail elements from 21.47 to 21 > Let me recalculate the values of the various components: > > a=55.47 m/s^2 (purple) b=27.73 m/s^2 (red) > > Purple x-comp = a sin( 21) = 19.88 (you got 51.62) > Purple y-comp = a cos( 21) = 51.79 (you got 20.3023) it is possible i mixed these two up, and _wrote_ a sin, when i _meant_ a cos. I will have to check the spreadsheet and the web page. Other than that, I think the other errors are from rounding. > Red x-comp = b cos(-48) = -18.55 (you got -18.9) > Red y-comp = b sin(-48) = -20.61 (you got -20.3021) > > I checked all cos and sin formulas in the drawing and all seem to be OK, the > only things that are wrong are the final decimal numbers. I will check that and get back to you. From popserver Sun Nov 26 06:58:02 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5058" "Sat" "25" "November" "1995" "22:53:57" "-0800" "Steve VanDevender" "stevev@efn.org" nil "94" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA06408; Sat, 25 Nov 95 22:50:53 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id WAA09366; Sat, 25 Nov 1995 22:53:57 -0800 Message-Id: <199511260653.WAA09366@tzadkiel.efn.org> In-Reply-To: References: <199511260108.RAA08463@tzadkiel.efn.org> X-UIDL: 817368889.001 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , Timothy van der Linden , KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 25 Nov 1995 22:53:57 -0800 Kevin C. Houston writes: > > We'll see. You must either absorb the photon and thereby absorb > > its momentum, or reflect the photon and get momentum to balance > > the change in direction of the photon. The only way to not get > > any momentum change is to either not interact with the photon or > > reflect it so as to leave it travelling in the same direction it > > came with the same energy. > > no, first the photon is reflected at an angle, this dumps some of the > momentum into the perpendicular directionthe photon leaves the first sail > element (reflection) and is absorbed in the second, inner element. as > far as that element is concerned, the photon came from the _front_ of the > ship. Look, I'm not doing this to dump on your parade, but it's a very simple check that I'm doing on your proposed solution to verify that it satisfies the laws of physics. We are looking at a system consisting of some quantity of photons with total momenergy [ p p 0 0 ] and a spacecraft with momenergy [ m 0 0 0 ], as seen in the frame where the spacecraft is initially at rest. No matter what, whether or not these two components interact, then the final total momenergy of all the resulting components must sum to [ m+p p 0 0 ]; in other words, the system has net forward momentum p always and forever. This is fundamental and inescapable. If you start out with a big box containing the photons and the spacecraft, then that box always has the same forward momentum for as long as all the original components remain in the box and nothing new is put in the box. Even worse for your argument, you are specifying that the photons are entirely absorbed by the spacecraft, meaning that the only component that is left after the interaction is the spacecraft, which must then have all the forward momentum. I know that my argument barely even uses math and must seem too simple to refute all the work you've put into this, but your solution fails to conserve momentum and is therefore physically invalid. > > If the system consisting of the photon beam and the spaceship > > plus sail assembly doesn't have the same momentum after the > > interaction as before, then you'll have to go back to the drawing > > board. Perhaps after a brief refresher course in physics. > > it does have the same momentum, just that some of that momentum has been > made to cancel out. equal but opposite momentums cancel out I think what your analysis is failing to account for, at some level, is that momentum is a vector quantity. Your think you have found a way to turn around part of the momentum and pit it against itself. Unfortunately that can't satisfy conservation of momentum. Not just the magnitude of the total system momentum, but the direction, must be conserved. You can't "dump momentum in the perpendicular direction.". Any forward momentum that you take away from the beam _must_ be transferred to the ship, whether the beam is reflected or absorbed, no matter the angle of the reflecting or absorbing surface; it cannot be transferred to momentum in any other direction. The structural loading caused by the beam does not absorb momentum continuously, because momentum implies motion -- unless you unhook the reflector or cut it into pieces, the reflector cannot accept momentum separately from the ship because it cannot move relative to the ship; a tiny amount of momentum goes into stretching the ship's structure when the beam is first turned on, and accounts for no more absorption after that. The only way to cancel out a quantity of momentum is to accept it from another source; you cannot take a single source of momentum and use one part of it to cancel another part of it. Again, let's start with what you've got -- photons with momenergy [ p p 0 0 ], and a spacecraft with momenergy [ m 0 0 0 ], for a total system momenergy [ m+p p 0 0 ]. When the photons bounce off the conical reflector tilted at an angle a, it changes the total photon momenergy from [ p p 0 0 ] to [ p*cos(2*a) -p*cos(2*a) 0 0 ]. The spacecraft then changes momenergy to [ m+p*(1-cos(2*a)) p*(1+cos(2*a)) 0 0 ]. The total system momenergy is still [ m+p p 0 0 ]. You have pitted the photon beam against itself, because the beam has been decollimated and individual photons now have sideways momentum that sums to zero for the entire beam, but that doesn't mean that the spacecraft doesn't gain momentum and energy to conserve the system momenergy [ m+p p 0 0 ]. Now the photons with momenergy [ p*cos(2*a) -p*cos(2*a) 0 0 ] travel back and hit the absorber (which need not be tilted or conical itself; it could just be a long column down the axis of the conical reflector). They transfer their momenergy into the collector, so the spacecraft momenergy changes to [ m+p p 0 0 ]. The spacecraft has net forward momentum. Momenergy has been conserved at all times throughout. There is no way to absorb the photons without absorbing their momentum. "I canna change the laws of physics, Captain." -- Chief Engineer Scott From popserver Sun Nov 26 23:12:13 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["5755" "Sun" "26" "November" "1995" "17:39:02" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199511261638.AA18646@student.utwente.nl>" "141" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA23834; Sun, 26 Nov 95 08:36:51 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA18646 (5.67b/IDA-1.5 for ); Sun, 26 Nov 1995 17:38:56 +0100 Message-Id: <199511261638.AA18646@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817427321.009 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sun, 26 Nov 1995 17:39:02 +0100 Reply To : Steve Reply From : Timothy >> I think I can't agree with that Steve, when the photon enters the first >> stage of the reflection, i.e. absorption, it adds some momentum to the ship. >> So the velocity of the ship increases. Now we enter the second stage of >> reflection, re-transmission. Relative to the ship the outgoing wavelength of >> the photon is the same as the incoming photon (because of invariance). But >> the observer at rest sees that that transmitted photon has dopplershifted >> (nice verb) and thus lost some energy. > >And I don't disagree with that analysis; it's correct in a frame >where the ship is moving. In that frame, the photon has more >energy and momentum, and while it changes momentum by the same >amount as in the frame where the ship is "stationary", this >necessarily results in a different-looking scenario. I was wrong to compare it with the police radar, so forget that part. But I still don't see what was wrong with part preceding it. o you say the photon looses energy if it accelerates the ship or do you say that the energy of the photon stays the same? What does that different scenario look like? >> Assuming these mirrors have mass, they indeed will get some velocity that >> correspondends to the same momentum as the photon. By each reflection the >> photon will loose some momentum and lower its wavelength. > >This is exactly the analysis I came up with. In the limit the >mirrors carry the momentum of the light pulse, and the light >pulse fades to nothing. Somehow we seem to agree on this, but I'm not sure why. >The way I was taught to measure mass is as sqrt(E^2 - p^2). So >the mass of a particle with energy E = gamma * m_rest and >momentum p = gamma * m_rest * v (where v is a vector) is > >m^2 = E^2 - p^2 > = gamma^2 * m_rest^2 - gamma^2 * m_rest^2 * abs(v)^2 > = gamma^2 * m_rest^2 * (1 - abs(v)^2) > = m_rest^2 > >(gamma is 1/sqrt(1 - abs(v)^2)). So no matter how the particle >moves it has the same mass. Mass is not energy. What you call >"relativistic mass" I call energy; what I call "mass" you seem to >want to call "rest mass", yet the quantity "mass" that I am using >doesn't vary with motion. This is what I was feeling; We think the same but use different terminology. What you call mass doesn't vary. I call that quantity rest-mass and that doesn't vary either. Taylor and Wheeler tell us that rest-mass revokes a potential misunderstanding so they call it invariant mass. I don't see why rest-mass would change when a body starts moving, I guess I've grown above that misunderstanding. You say the energy changes while I say the relativistic-mass or the kinetic energy changes. This kinetic energy is not the classical 0.5mv^2 but m_rest*c^2(gamma-1) Or more clear the total energy minus the rest-energy. > > >If, on the other hand, a moving object did exert greater > > >gravitation than a stationary object of the same mass, I'd > > >probably be looking for a relation to a quantity that did change, > > >like the object's total energy. > > > > So that would mean that some of the change in energy is change of > > gravitational energy, from which I would conclude that it comes from extra > > mass (or bending of space time). > >First you have to convince me that a moving object really does >exert more gravitational force. Let me quote a few sentences of "Introducing Einstein's relativity" by Ray d'Inverno in the paragraph "The principle of equivalence": Next, we wish to make explicit the assumption that matter both responds to, and is a source of, a gravitational field. However, we have seen in special relativity that matter and energy are equivalent, so the statement about the gravitational field applies to energy as well. This means that even photons excert and react to gravity as well as all other kinds of energy. I would conclude from this that moving bodies excert greater gravitation either because of gain of mass or gain of energy. I feel both can be used, its a bit like the wave-particle duality. >> Is it this translation of energy to mass that gives the trouble? > >It is that my studies of relativistic kinematics do not allow for >the treatment of energy and mass as identical quantities. They are indeed not identical but equivalent, meaning they can be be interchanged. =============================================================================== ReplyTo : Kevin ReplyFrom : Tim >BTW, in english, a nitwit is a stupid person. (someone with the brains >of a nit ) in so naming myself, I admit my previous errors Yes, I knew, I looked it up in a dictionary, it was just a repeat of your own words. >actually, it's Kevin, I know it can be confusing when three or more >people are engaged in debate, but try to keep us straight. It's not nice >to insult Steve's intelligence like that. I guess, it was a bit late when I wrote that just after I finished the letter to Steve which occupied my mind. >not very, considering i lost it (or it was stolen), I've been using EXCEL >for my calculations, also, I rounded the actual angle of the sail >elements from 21.47 to 21 I figured you used tables or something like that. Anyway here are some extra corrections of my calculations: >> Red x-comp = b cos(-48) = -18.55 (you got -18.9) ^ should be positive And I made mistakes in the general formulas, so here are the right ones: Px=2b sin(t) Py=2b cos(t) Rx=b sin(2t-180)=- b sin(2t) Ry=b cos(2t-180)=- b cos(2t) x=Px+Rx=2b sin(t) - b sin(2t) y=Py+Ry=2b cos(t) - b cos(2t) t=90 gives y=b which is logical because that means that if there is no mirror the energy is captured right away. Every other angle makes the problem worse! From popserver Sun Nov 26 23:12:20 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["5258" "Sun" "26" "November" "1995" "12:40:51" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "122" "Okay, I give up ( well, not exactly ;)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA01070; Sun, 26 Nov 95 10:39:09 PST Received: by maroon.tc.umn.edu; Sun, 26 Nov 95 12:40:52 -0600 In-Reply-To: <199511260653.WAA09366@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817427321.014 From: Kevin C Houston To: Steve VanDevender Cc: Timothy van der Linden , KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David Levine Subject: Okay, I give up ( well, not exactly ;) Date: Sun, 26 Nov 1995 12:40:51 -0600 (CST) On Sat, 25 Nov 1995, Steve VanDevender wrote: > Look, I'm not doing this to dump on your parade, but it's a very > simple check that I'm doing on your proposed solution to verify > that it satisfies the laws of physics. i know you aren't doing this to be mean, I'm just frustrated by the situation. I checked my spreadsheet again, and found a cos where a sin should be, and vice versa. > > We are looking at a system consisting of some quantity of photons > with total momenergy [ p p 0 0 ] and a spacecraft with momenergy > [ m 0 0 0 ], as seen in the frame where the spacecraft is > initially at rest. No matter what, whether or not these two > components interact, then the final total momenergy of all the > resulting components must sum to [ m+p p 0 0 ]; in other words, > the system has net forward momentum p always and forever. This > is fundamental and inescapable. If you start out with a big box > containing the photons and the spacecraft, then that box always > has the same forward momentum for as long as all the original > components remain in the box and nothing new is put in the box. > Even worse for your argument, you are specifying that the photons > are entirely absorbed by the spacecraft, meaning that the only > component that is left after the interaction is the spacecraft, > which must then have all the forward momentum. > Yes, I should have known this. in Chem Eng, we use the concept of a control volume all the time. > I know that my argument barely even uses math and must seem too > simple to refute all the work you've put into this, but your > solution fails to conserve momentum and is therefore physically > invalid. > Simple arguments can convince simple minds (like mine) > > it does have the same momentum, just that some of that momentum has been > > made to cancel out. equal but opposite momentums cancel out > > I think what your analysis is failing to account for, at some > level, is that momentum is a vector quantity. Your think you > have found a way to turn around part of the momentum and pit it > against itself. Unfortunately that can't satisfy conservation of > momentum. Not just the magnitude of the total system momentum, > but the direction, must be conserved. You can't "dump momentum > in the perpendicular direction.". Any forward momentum that you > take away from the beam _must_ be transferred to the ship, > whether the beam is reflected or absorbed, no matter the angle of > the reflecting or absorbing surface; it cannot be transferred to > momentum in any other direction. The structural loading caused > by the beam does not absorb momentum continuously, because > momentum implies motion -- unless you unhook the reflector or cut > it into pieces, the reflector cannot accept momentum separately > from the ship because it cannot move relative to the ship; a tiny > amount of momentum goes into stretching the ship's structure when > the beam is first turned on, and accounts for no more absorption > after that. The only way to cancel out a quantity of momentum is > to accept it from another source; you cannot take a single source > of momentum and use one part of it to cancel another part of it. Agreed that the way i proposed won't work, why can't a single source be decomposed and used to cancel itself? It can be done with light, a single beam can be split, half the beam can have it's phase delayed by 1/2 wavelength, and then recombined with the other half of the beam, the net result is _nothing_ no beam. they destructively interfere. Since any particle or energy can be considered a wave, (debroglie wave for momentum) why can't this same trick be used? > > "I canna change the laws of physics, Captain." > -- Chief Engineer Scott "any science, sufficiently advanced, is indistinguishable from magic" -- Arthur C Clarke Okay, If I can't raise the bridge, perhaps I can lower the river. in studying the equations again, the big problem seem to be the exhaust velocity. (I think we knew all along that Ve= .99996 C was impossible) if i turn down the Exhaust velocity, then the exhaust invarient mass must increase. The original reason to increase the exhaust velocity was to conserve RM. but if we can use a maser sail for the first half of the trip, we might be able to accept a higher RM rate for the decell portion of the trip. so here's what I need: a simple easy to use, relativisticlly correct formula that tells me how much energy I need to accelerate a given exhaust mass to a given speed. I'll be using Me=G*(Ms+Mf) * gamma/(Ve *C) where Ve is exhaust Velocity expressed as a fraction of C. Me is Exhaust Mass. Ms is ship's Mass. Mf is Reaction Mass. G is ship's acceleration. gamma is SQRT(1 - Ve^2) I know Tim likes gamma= 1/sqrt(1-Ve^2), but then he divides by it instead of multipling. all mass is invarient or rest mass. Ve is with respect to the ship, and I'm thinking it'll be in the .80-.9? perecent of C range. every time I try to calculate this, I get flamed for using the wrong formula. Timothy gave me one, but then said that you (Steve) had problems with it. so I thought I'd head off any potential problems by asking for the right formula ahead of time. Kevin From popserver Sun Nov 26 23:12:40 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1671" "Sun" "26" "November" "1995" "23:19:37" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "47" "Re: Okay, I give up ( well, not exactly ;)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA12507; Sun, 26 Nov 95 14:17:14 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA01202 (5.67b/IDA-1.5 for ); Sun, 26 Nov 1995 23:19:34 +0100 Message-Id: <199511262219.AA01202@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817427321.029 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Okay, I give up ( well, not exactly ;) Date: Sun, 26 Nov 1995 23:19:37 +0100 >if i turn down the Exhaust velocity, then the exhaust invarient mass must >increase. The original reason to increase the exhaust velocity was to >conserve RM. but if we can use a maser sail for the first half of the >trip, we might be able to accept a higher RM rate for the decell portion >of the trip. Going from 0.99996c to 0.85c means about 60 times more reaction mass... Plus since we can't use a maser beam for energy we have to bring the energy ourselves. >so here's what I need: > >a simple easy to use, relativisticlly correct formula that tells me how much >energy I need to accelerate a given exhaust mass to a given speed. > >I'll be using Me=G*(Ms+Mf) * gamma/(Ve *C) > >where >Ve is exhaust Velocity expressed as a fraction of C. >Me is Exhaust Mass. >Ms is ship's Mass. >Mf is Reaction Mass. >G is ship's acceleration. >gamma is SQRT(1 - Ve^2) I know Tim likes gamma= 1/sqrt(1-Ve^2), but then > he divides by it instead of multipling. In most formulas I use, I have to multiply by gamma. Your formula is one of few where I have to devide by it. >all mass is invarient or rest mass. >Ve is with respect to the ship, and I'm thinking it'll be in the .80-.9? >perecent of C range. To calculate the kinetic energy of a mass M use: K=M C^2 (1/gamma - 1) where gamma is according to your (unusual?) definition. You can substitute Me for M and simplify: K=G C (Ms+Mf) (1-gamma)/Ve (gamma is still according to your definition) Timothy P.S. If you are planning to calculate how much energy is needed to accelerate the Asimov and it's fuel&reaction mass for specific G, I've to tell you that these calculations have been done already. From popserver Mon Nov 27 00:28:25 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3760" "Sun" "26" "November" "1995" "16:25:36" "-0800" "Steve VanDevender" "stevev@efn.org" nil "93" "Okay, I give up ( well, not exactly ;)" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA19292; Sun, 26 Nov 95 16:22:32 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id QAA11700; Sun, 26 Nov 1995 16:25:36 -0800 Message-Id: <199511270025.QAA11700@tzadkiel.efn.org> In-Reply-To: References: <199511260653.WAA09366@tzadkiel.efn.org> X-UIDL: 817431908.000 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , Timothy van der Linden , KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David Levine Subject: Okay, I give up ( well, not exactly ;) Date: Sun, 26 Nov 1995 16:25:36 -0800 Kevin C. Houston writes: > > The only way to cancel out a quantity of momentum is > > to accept it from another source; you cannot take a single source > > of momentum and use one part of it to cancel another part of it. > > Agreed that the way i proposed won't work, why can't a single source be > decomposed and used to cancel itself? It can be done with light, a > single beam can be split, half the beam can have it's phase delayed by > 1/2 wavelength, and then recombined with the other half of the beam, the > net result is _nothing_ no beam. they destructively interfere. Since > any particle or energy can be considered a wave, (debroglie wave for > momentum) why can't this same trick be used? No matter what, the momentum has to go somewhere. You can't split a momentum vector in half and turn one of the halves around without creating another momentum vector of magnitude and direction equal to the original to preserve conservation. If you use a mirror to reflect half of the light back on itself, then you get all the momentum of the original beam -- the mirror (and whatever it's attached to) acquires 2 * (1/2 * p) = p momentum for reflecting half of the beam backwards. If you take half the beam and delay it by half a wavelength before retransmitting it forward to combine with the other half of the beam, you don't get the momentum, but you also don't get any of the energy. Unfortunately I'm at a bit of a loss to say where the momentum goes in this case. I also don't think that out-of-phase photons annihilate when they meet. In the region that the out-of-phase photons overlap, they cancel, but they can't just disappear forever. > > "I canna change the laws of physics, Captain." > > -- Chief Engineer Scott > > "any science, sufficiently advanced, is indistinguishable from magic" > -- Arthur C Clarke Any science, sufficiently advanced, still cannot violate its own fundamental laws. > so here's what I need: > > a simple easy to use, relativisticlly correct formula that > tells me how much energy I need to accelerate a given exhaust > mass to a given speed. As far as I know, that can be done with the standard relativistic kinetic energy formula: KE = m * c^2 * ((1 / sqrt(1 - v^2 / c^2)) - 1) > I'll be using Me=G*(Ms+Mf) * gamma/(Ve *C) > > where > Ve is exhaust Velocity expressed as a fraction of C. > Me is Exhaust Mass. > Ms is ship's Mass. > Mf is Reaction Mass. > G is ship's acceleration. > gamma is SQRT(1 - Ve^2) I know Tim likes gamma= 1/sqrt(1-Ve^2), but then > he divides by it instead of multipling. > > all mass is invarient or rest mass. > Ve is with respect to the ship, and I'm thinking it'll be in the .80-.9? > perecent of C range. Whoa. Where did this come from? How is this related to your requirement above? You should know that _every_ text I've read says that gamma is 1 / sqrt(1 - v^2), so your use is unconventional and may confuse people. Could you at least give some information about how you derived this? I can say right off that it doesn't look right because it doesn't have consistent units; the right-hand side evaluates to units of kg/s. > every time I try to calculate this, I get flamed for using the > wrong formula. Timothy gave me one, but then said that you > (Steve) had problems with it. so I thought I'd head off any > potential problems by asking for the right formula ahead of > time. I don't remember when I might have said this or what formula it was about any more. I'll get back to you on the formula question. I can adapt some of the work I did before, but I think it would be more useful if I cast it in terms of reaction mass and payload mass rather than fractional quantities. From popserver Mon Nov 27 00:53:37 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4157" "Sun" "26" "November" "1995" "16:49:49" "-0800" "Steve VanDevender" "stevev@efn.org" nil "99" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA20876; Sun, 26 Nov 95 16:46:40 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id QAA11752; Sun, 26 Nov 1995 16:49:49 -0800 Message-Id: <199511270049.QAA11752@tzadkiel.efn.org> In-Reply-To: <199511261638.AA18646@student.utwente.nl> References: <199511261638.AA18646@student.utwente.nl> X-UIDL: 817433420.000 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sun, 26 Nov 1995 16:49:49 -0800 Timothy van der Linden writes: > >And I don't disagree with that analysis; it's correct in a frame > >where the ship is moving. In that frame, the photon has more > >energy and momentum, and while it changes momentum by the same > >amount as in the frame where the ship is "stationary", this > >necessarily results in a different-looking scenario. > > I was wrong to compare it with the police radar, so forget that part. But I > still don't see what was wrong with part preceding it. > o you say the photon looses energy if it accelerates the ship or do you say > that the energy of the photon stays the same? > What does that different scenario look like? In a frame where the ship is in motion, the photon changes energy when it bounces off the ship; its reflected energy is less than the incident energy if the ship receding, greater if the ship is approaching. You actually were right to compare this to doppler radar, because it's this effect that doppler radar measures to determine velocity. > >> Assuming these mirrors have mass, they indeed will get some velocity that > >> correspondends to the same momentum as the photon. By each reflection the > >> photon will loose some momentum and lower its wavelength. > > > >This is exactly the analysis I came up with. In the limit the > >mirrors carry the momentum of the light pulse, and the light > >pulse fades to nothing. > > Somehow we seem to agree on this, but I'm not sure why. Because we're both thinking about it the right way? :-) > >First you have to convince me that a moving object really does > >exert more gravitational force. > > Let me quote a few sentences of "Introducing Einstein's relativity" by Ray > d'Inverno in the paragraph "The principle of equivalence": > > Next, we wish to make explicit the assumption that matter > both responds to, and is a source of, a gravitational > field. However, we have seen in special relativity that > matter and energy are equivalent, so the statement about the > gravitational field applies to energy as well. > > This means that even photons excert and react to gravity as well as all > other kinds of energy. This is true, but it's more complicated than you make it out to be. Note that I will continue to use Taylor and Wheeler's terminology, so when I say "mass", I mean invariant mass. A photon is massless, because it has energy equal to its momentum, and the magnitude of its momenergy vector is 0. However, multiple photons considered as a system may not be massless! For example, two photons with energy/momentum p travelling in opposite directions have mass 2p: [ p p 0 0 ] + [ p -p 0 0 ] = [ 2*p 0 0 0 ] magnitude [ 2*p 0 0 0 ] = 2*p Two photons travelling at right angles to each other also have mass: [ p p 0 0 ] + [ p 0 p 0 ] = [ 2*p p p 0 ] magnitude [ 2*p p p 0 ] = sqrt(2) * p Two photons travelling in parallel have no mass: magnitude [ 2*p 2*p 0 0 ] = 0 An absorber gains mass as well as momentum from a massless photon: [ m 0 0 0 ] + [ p p 0 0 ] = [ m+p p 0 0 ] magnitude [ m+p p 0 0 ] = sqrt((m + p)^2 - p^2) = sqrt(m^2 + 2 * p * m) Mass is a more subtle concept than energy; while energies add linearly, masses as magnitudes of momenergy vectors do not. > I would conclude from this that moving bodies excert greater gravitation > either because of gain of mass or gain of energy. I feel both can be used, > its a bit like the wave-particle duality. What I really want to see is the general relativistic formula that says whether spacetime curvature is the result of an object's mass or its energy. > >> Is it this translation of energy to mass that gives the trouble? > > > >It is that my studies of relativistic kinematics do not allow for > >the treatment of energy and mass as identical quantities. > > They are indeed not identical but equivalent, meaning they can be be > interchanged. Not in Taylor and Wheeler's terminology. The only time they allow mass and energy to be spoken of as equivalent is when you are dealing with an object in its rest frame. In any other frame the object's energy is not equivalent to its mass. From popserver Mon Nov 27 06:12:58 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["991" "Sun" "26" "November" "1995" "22:46:11" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951126224608_34896815@emout05.mail.aol.com>" "21" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA29951; Sun, 26 Nov 95 19:46:00 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id WAA21545; Sun, 26 Nov 1995 22:46:11 -0500 Message-Id: <951126224608_34896815@emout05.mail.aol.com> X-UIDL: 817452572.003 From: KellySt@aol.com To: stevev@efn.org Cc: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu Subject: Re: Engineering Newsletter Date: Sun, 26 Nov 1995 22:46:11 -0500 KellySt@aol.com writes: > The papers I've seen on on solar sails seem to disagree with > you. RThey propose angling the sial to alter the thrust > vector. Which would be impossible if the momenum transfer was > always in the direction of the photons origional vector. >>You don't seem to have read what I wrote, so I'll repeat it below. > >> A reflected photon transfers momentum to a reflector normal to > >> the reflecting surface. We seem to have a com error here. From your previous statments it sounded like you beleaved all thrust would be in the direction of the origional light sources and that you couldn't divert some of the thrust into a lateral force. I.E. cut the forward thrust down. I never sugested you could reverse thrust on a light sail. Part of the problem on my end might have been my use of a light sail as an example. With a light sail you don't thrust away from the sun. You thrust laterally to slow down or speed up along your orbit vector. Kelly From popserver Mon Nov 27 06:13:06 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1130" "Sun" "26" "November" "1995" "22:46:36" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "24" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA29967; Sun, 26 Nov 95 19:46:30 PST Received: by emout06.mail.aol.com (8.6.12/8.6.12) id WAA04896; Sun, 26 Nov 1995 22:46:36 -0500 Message-Id: <951126224630_34897228@emout06.mail.aol.com> X-UIDL: 817452572.004 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sun, 26 Nov 1995 22:46:36 -0500 ReplyTo : Kelly ReplyFrom : Timothy >I agree that we are stuck without a new power source. Kevins microwave >system or my Externally fueled system are at best theoretical possibilities, >with no real credible way to build them. >> Externally fueled did that mean scooping? I'm not sure >> anymore, please tell me if my assumption is right. Not quite. In my Exporer ship design I assumed the fusion fuel was launched ahead of the ship with a linear accelerator. As the ship accelerates it contiually scoops up pre launched fuel going at nearly its speed. So the ship looses very little momentum scooping up the fuel packets. That would allow you to get up to light speed with "only" 200 times the ships mas in fusion fuel. However like Kevins system. We have a serious problem stoping. I though using a ramscope to produce a lot of drag might do it, but never found a good woorkup of the numbers. By the way. Did anyone calculate the drag on the sail structure from interstelar debre? If you can maintain enough of an electric charge to use the microwave sail as a parachute that might help with stoping. Kelly From popserver Mon Nov 27 06:13:09 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3115" "Sun" "26" "November" "1995" "22:46:54" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951126224644_34897493@emout05.mail.aol.com>" "60" "Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA00132; Sun, 26 Nov 95 19:47:33 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id WAA21838; Sun, 26 Nov 1995 22:46:54 -0500 Message-Id: <951126224644_34897493@emout05.mail.aol.com> X-UIDL: 817452572.005 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org Cc: T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Summarry of the momentum wars and idea. Date: Sun, 26 Nov 1995 22:46:54 -0500 Ok, I'm geting lost in all these cascading arguments and equations. So to try to make sure we have an agreement, I'll try to sumarize. A beam of microwave photons headed in the direction of the ship hits a conical set of mesh sails. Because of the shallow angle of the sails, the photons bounce off the sail moving inward. Because of the shallow angle most of the resulting thrust vector is pointing outward and is canceled out by the oposite side of the sail (I.E. most of the thrust on the sail, or momentum if you prefer is concerted to a thrust load on the sail. No velocity change to ship or sail.), the remaining foward part of the thrust vector does push the ship forward, but at reduced levels. At this point the photons are moving forward and inward toward the ships axis. (Some energy and/or momentum was lost in the first reflection.) This photon stream them hits a power converter, or waveguide feed into the engines or something. At the point of the interaction it still has most its velocity in a forward vector, and about all we've done is cut this amount down due to reflections and power loses as it attempted to rip apart the sail. Are we all agreed on this? Question. Diverted beams of photons converge on a forward pointing cone. This (not considering the beam cancelation due to interfearence, reflection loses, and other such nonsence) is the origional beam moving forward in a much more concentrated form than its pre sail moments. Net thrust to the ship near zip (give or take). In frount of this stream we put an ionized reaction mass. Beam slams into it and throws it forward. A) A lot of the beam (most?) would reflect back off the ionized reaction mass (micro-waves do that off ionized matter) Would this act as Forward's sacrificial outer-sail in "Dragons egg (?)"? I.E. could we use the forwardly reflected beam for drive power? Efectivly the reaction mass (now renamed plasma reflection mass) has gotten boosted forward at a hellish speed, but bounced the beam back down our throats. (Just like Forwards outer drop sail.) We would have to continuously replenish this "reflection mass", but on the bright side we could be very sure it will clean all the interstellar mass out from in frount of the ship. ;) B) Instead of just dumping this superheated reflect mass forward. How about using it as a rocket stream also. At the least we can ride the expanding shock wave from the stuff. Anyway, between A & B we have used part of the beam to create a high temp plasma thurst, and reflected the rest off said plasma onto a rearwardly reflective part of the ship. Momentum/kinetic energy interactions between the beam and the ship are pretty much canceled out until it hits the reaction/reflection mass. The ship needs NO POWER CONVERTERS! We never convert it to electricity to drive an accelerator. (Ok, ok, we convert a little to run the ship and power the magnetic feilds that keep the plasma off the back of the ship.) But other than that, we just reflect it around and feed it mass. Thoughts? (or are we still arguing about momentum and such?) Kelly From popserver Mon Nov 27 08:07:48 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3869" "Mon" "27" "November" "1995" "00:05:31" "-0800" "Steve VanDevender" "stevev@efn.org" nil "77" "Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA09753; Mon, 27 Nov 95 00:02:21 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id AAA12825; Mon, 27 Nov 1995 00:05:31 -0800 Message-Id: <199511270805.AAA12825@tzadkiel.efn.org> In-Reply-To: <951126224644_34897493@emout05.mail.aol.com> References: <951126224644_34897493@emout05.mail.aol.com> X-UIDL: 817459469.000 From: Steve VanDevender To: KellySt@aol.com Cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 00:05:31 -0800 KellySt@aol.com writes: > Ok, I'm geting lost in all these cascading arguments and > equations. So to try to make sure we have an agreement, I'll > try to sumarize. If you can't stand the math get out of the physics. > A beam of microwave photons headed in the direction of the > ship hits a conical set of mesh sails. Because of the shallow > angle of the sails, the photons bounce off the sail moving > inward. Because of the shallow angle most of the resulting > thrust vector is pointing outward and is canceled out by the > oposite side of the sail (I.E. most of the thrust on the sail, > or momentum if you prefer is concerted to a thrust load on the > sail. No velocity change to ship or sail.), the remaining > foward part of the thrust vector does push the ship forward, > but at reduced levels. > > At this point the photons are moving forward and inward toward > the ships axis. (Some energy and/or momentum was lost in the > first reflection.) This photon stream them hits a power > converter, or waveguide feed into the engines or something. > At the point of the interaction it still has most its velocity > in a forward vector, and about all we've done is cut this > amount down due to reflections and power loses as it attempted > to rip apart the sail. > > Are we all agreed on this? Something that I don't think everyone is grasping in these so-called "momentum wars" is that momentum is a vector quantity, not a scalar quantity. That means that two momentum vectors with identical magnitudes that point in different directions are different quantities of momentum, and one momentum vector cannot be converted to the other. You can redirect a photon beam laterally by reflection. By changing the beam's direction, the reflector must develop momentum to conserve the original quantity that the photon beam had before the reflection. I think even those of us who are doing the right things with momentum conservation are confusing others by erroneously saying that the reflected beam has the same momentum as the original beam. It does not, because the reflected beam is traveling in a different direction. You simply cannot change the total quantity of momentum in a system, ever. A piece of the system can change its momentum by exchanging momentum with other pieces, but no matter what it does it cannot change the sum of the momenta of all the pieces. So the simple physical constraint in the system consisting of the photon beam and the spaceship is that the total momentum of the beam and ship remains the same before, during, and after _any_ interaction between them. If the ship is to absorb the photon beam, it _must_ absorb the momentum too. Besides not treating momentum as a vector quantity, people are making the mistake of thinking that lateral loading of the sail assembly is a magical sink for momentum or energy. The error is in thinking that stress on a static structure absorbs energy or momentum continuously over time. If the sail does not move relative to the ship, then it cannot absorb or dissipate momentum separately from the ship. It cannot absorb momentum if it does not move, because momentum means motion. For just an instant, once, when the beam first touches the sail, the beam does work on the static structure to stretch the sail and support members, which absorb a small quantity of energy. From that point on, as long as the sail does not fall apart or the support members do not break, no more energy is dissipated into loading of the sail structure. The reality that static stress does not continue to dissipate energy over time is not intuitive, because our muscles aren't static structures like boards or rods or wires; they must dissipate energy even to hold a weight motionless above your head, while a table holding the same weight does not dissipate energy. From popserver Mon Nov 27 19:07:15 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["506" "Mon" "27" "November" "1995" "11:25:05" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "21" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA28268; Mon, 27 Nov 95 09:24:55 PST Received: by maroon.tc.umn.edu; Mon, 27 Nov 95 11:25:06 -0600 In-Reply-To: <199511270805.AAA12825@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817499001.017 From: Kevin C Houston To: Steve VanDevender Cc: KellySt@aol.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 11:25:05 -0600 (CST) to:all Re; Finals week. I don't think I'll be contribiting too much in the next week or so, but I'll be listening. quick notes. the "momentum" happens every second, so it's actually an acelleration. many structures (static tho they be) resist continuous acceleration all the time by providing opposing compressive or tensile forces rocket equation units should have units of Kg/sec, because that is a mass flow rate. parasail formulas a=.... are units of acelleration. that's all for now. Kevin From popserver Mon Nov 27 21:37:26 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1172" "Mon" "27" "November" "1995" "12:00:59" "-0800" "Steve VanDevender" "stevev@efn.org" nil "35" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA08629; Mon, 27 Nov 95 11:57:45 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id MAA17208; Mon, 27 Nov 1995 12:00:59 -0800 Message-Id: <199511272000.MAA17208@tzadkiel.efn.org> In-Reply-To: References: <199511270805.AAA12825@tzadkiel.efn.org> X-UIDL: 817508043.000 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 12:00:59 -0800 Kevin C. Houston writes: > the "momentum" happens every second, so it's actually an acelleration. That won't get you out of conservation of momentum. The system must change momentum per unit time to equal the amount of momentum added per unit time. > many structures (static tho they be) resist continuous acceleration all > the time by providing opposing compressive or tensile forces The opposing forces are some finite amount of energy that is loaded into the system once. Once the structure is loaded it does not absorb any more energy. If a static structure had to dissipate energy continuously to remain standing, where would such energy come from? Why doesn't your house fall down? Where are the batteries? > rocket equation units should have units of Kg/sec, because that is a mass > flow rate. The equation I was talking about: Me=G*(Ms+Mf) * gamma/(Ve *C) where Ve is exhaust Velocity expressed as a fraction of C. Me is Exhaust Mass. Ms is ship's Mass. Mf is Reaction Mass. G is ship's acceleration. gamma is SQRT(1 - Ve^2 It is inconsistent since it has units of mass on the left, units of mass/time on the right. From popserver Mon Nov 27 21:37:37 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["2454" "Mon" "27" "November" "1995" "14:22:24" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "69" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA10318; Mon, 27 Nov 95 12:24:36 PST Received: by maroon.tc.umn.edu; Mon, 27 Nov 95 14:22:28 -0600 In-Reply-To: <199511272000.MAA17208@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817508043.008 From: Kevin C Houston To: Steve VanDevender Cc: Steve VanDevender , KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 14:22:24 -0600 (CST) On Mon, 27 Nov 1995, Steve VanDevender wrote: > Kevin C. Houston writes: > > the "momentum" happens every second, so it's actually an acelleration. > > That won't get you out of conservation of momentum. The system > must change momentum per unit time to equal the amount of > momentum added per unit time. > > > many structures (static tho they be) resist continuous acceleration all > > the time by providing opposing compressive or tensile forces > > The opposing forces are some finite amount of energy that is > loaded into the system once. Once the structure is loaded it > does not absorb any more energy. > > If a static structure had to dissipate energy continuously to > remain standing, where would such energy come from? Why doesn't > your house fall down? Where are the batteries? good question, it actually proves my point. consider the following experiment. (easy enough to do in reality, but a thought exp here.) take a flat plate. punch three holes equally spaced along the perimeter. attach a piece of wire to each hole and suspend it from the ceiling. shoot (or drop) a lot of ball bearings onto the plate. provided the wires don't break, the bb's encounter the plate from above, but leave it (in all directions) to the side. since bb's eneter the control volume every second, and leave only from the sides, the plate "feels" a net downward force. provided the force does not overcome the wires tensile strength, this situation is stable. where does the energy come from? nowhere, since there is no net loss of momentum, only a change in y for a given change in x. While this gedenkanexperiment proves your point on photon thrust, (i.e. the bb's changed course) it also proves my point on tensile forces. (the wires don't break) > > > rocket equation units should have units of Kg/sec, because that is a mass > > flow rate. > > The equation I was talking about: > > Me=G*(Ms+Mf) * gamma/(Ve *C) > > where > Ve is exhaust Velocity expressed as a fraction of C. > Me is Exhaust Mass. > Ms is ship's Mass. > Mf is Reaction Mass. > G is ship's acceleration. > gamma is SQRT(1 - Ve^2 > > It is inconsistent since it has units of mass on the left, units > of mass/time on the right. > Sorry, I was unclear. Me has units of mass/second since it is the mass flow per unit time. if my gamma is unconventional, I will gladly change. it makes no difference to me. Kevin From popserver Mon Nov 27 22:23:18 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3039" "Mon" "27" "November" "1995" "14:20:15" "-0800" "Steve VanDevender" "stevev@efn.org" nil "58" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA17485; Mon, 27 Nov 95 14:16:59 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id OAA17530; Mon, 27 Nov 1995 14:20:15 -0800 Message-Id: <199511272220.OAA17530@tzadkiel.efn.org> In-Reply-To: References: <199511272000.MAA17208@tzadkiel.efn.org> X-UIDL: 817510794.001 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 14:20:15 -0800 Kevin C. Houston writes: > > The opposing forces are some finite amount of energy that is > > loaded into the system once. Once the structure is loaded it > > does not absorb any more energy. > > > > If a static structure had to dissipate energy continuously to > > remain standing, where would such energy come from? Why doesn't > > your house fall down? Where are the batteries? > > good question, it actually proves my point. consider the following > experiment. (easy enough to do in reality, but a thought exp here.) > > take a flat plate. punch three holes equally spaced along the perimeter. > attach a piece of wire to each hole and suspend it from the ceiling. > shoot (or drop) a lot of ball bearings onto the plate. > provided the wires don't break, the bb's encounter the plate from above, > but leave it (in all directions) to the side. > since bb's eneter the control volume every second, and leave only from > the sides, the plate "feels" a net downward force. > provided the force does not overcome the wires tensile strength, this > situation is stable. where does the energy come from? nowhere, since > there is no net loss of momentum, only a change in y for a given change > in x. > > While this gedenkanexperiment proves your point on photon thrust, > (i.e. the bb's changed course) it also proves my point on tensile > forces. (the wires don't break) Your experiment works as it does only because the momentum from the ball bearings is transferred into the structure that supports the plate, and because you're not including that structure in your "control volume", you're not properly accounting for the momentum of the system. If you do this in space by shooting ball bearings at a plate attached by wires to another structure, the plate and the structure will acquire momentum and start moving as the ball bearings bounce off the plate. The principle of conservation of momentum that has stood since Newton (and that was not modified by Einstein) is tricky to apply in everyday life, because there are a lot of things that complicate it when you're living in an atmosphere on a planet with materials that have friction. When you jump off the ground, the ground also moves away from you under your feet, although by a factor of 10^-23 less (you mass maybe 60 kg; the Earth masses 6e24 kg). When you raise the ball bearings up to drop them on the plate, the center of mass of the Earth moves downward just a tiny amount to compensate. When you drop the bearings, the center of mass of the Earth moves back up, and counterbalances the momentum gained by the plate attached by wires to the structure that is sitting on the Earth. Because this movement is practically unmeasurable, it's easy to ignore it as you did. In a vacuum, in zero gravity, without huge masses that make small changes in momentum unmeasurable, we have conservation of momentum the way Newton imagined it, pure and clean and simple. For every action there is an equal and opposite reaction. From popserver Mon Nov 27 22:28:24 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1495" "Mon" "27" "November" "1995" "14:20:12" "-0800" "Steve VanDevender" "stevev@efn.org" nil "32" "Eureka! We've invented the reactionless drive!" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA17478; Mon, 27 Nov 95 14:16:57 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id OAA17529; Mon, 27 Nov 1995 14:20:12 -0800 Message-Id: <199511272220.OAA17529@tzadkiel.efn.org> In-Reply-To: <199511270805.AAA12825@tzadkiel.efn.org> References: <951126224644_34897493@emout05.mail.aol.com> <199511270805.AAA12825@tzadkiel.efn.org> X-UIDL: 817511101.000 From: Steve VanDevender To: Steve VanDevender Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Eureka! We've invented the reactionless drive! Date: Mon, 27 Nov 1995 14:20:12 -0800 Kevin's invention of a momentum-absorbing structure will be one of the great inventions of history, if it pans out. That's because it could be used to create a reactionless drive. Put Kevin's parasail and a powerful laser inside your ship, and just shine the laser at the parasail. You'll start moving in the direction opposite the direction the laser is pointing. The structure doesn't have to be exposed to space or anything; you could just have a box in the engine room containing the parasail-laser assembly. You can even use the parasail's absorber to power the laser (with some auxiliary generator to compensate for inefficiency losses). Here's what would happen: The laser turns on, and generates forward momentum in the ship in reaction to the backward momentum of the laser light. The laser light is absorbed by the parasail, producing some smaller amount of backward momentum than the forward momentum the ship got in reaction to the laser. There's more forward momentum than backward momentum, so the box produces net forward momentum without reaction mass. A lower-tech solution could involve a bunch of BB cannons shooting at a more sturdy version of the parasail assembly. The best part is that if the parasail recovers most of the energy directed at it, you can keep pumping that energy back in to the laser or BB cannons or whatever is providing the thrust; if you can make this efficient enough, you can get huge amounts of momentum for small quantities of energy. From popserver Tue Nov 28 02:05:36 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1187" "Mon" "27" "November" "1995" "17:28:48" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "27" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from wolfe.net (mail1.wolfe.net) by efn.efn.org (4.1/smail2.5/05-07-92) id AA29591; Mon, 27 Nov 95 17:21:13 PST Received: from sea-ts2-p50.wolfenet.com (sea-ts2-p50.wolfenet.com [204.157.98.168]) by wolfe.net (8.7/8.7) with SMTP id RAA01699; Mon, 27 Nov 1995 17:28:48 -0800 (PST) Message-Id: <199511280128.RAA01699@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817524126.003 From: rddesign@wolfenet.com To: Steve VanDevender Cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 27 Nov 1995 17:28:48 -0800 (PST) >KellySt@aol.com writes: > > > Ok, I'm geting lost in all these cascading arguments and > > equations. So to try to make sure we have an agreement, I'll > > try to sumarize. > >If you can't stand the math get out of the physics. > Ric writes: I have never even dreamed of ever understanding the physics of this but let me toss some stuff out from a dummy's view point. The impression I'm getting is that we can send the power to get us to TC but we can't stop. Correct? How about a hermaphrodite ship. We load it up with reaction mass and hold it in reserve. At mid point we turn the ship, (I know, I know, we've been over this before.) We furl the sail first. ( how we do this is the engineers problem) Turn the ship, begin tossing the reaction mass in the ram and begin the slowing process. As we get nearer to TC unfurl the sail and begin using TC as well as the reaction mass to help slow the ship. I just don't see how many times we can keep running around this topic until we see that with our present technology we don't have too many other choices. OK, guys tear it apart. :-) ( God how I love being canon fodder) The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Tue Nov 28 07:42:09 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["2783" "Mon" "27" "November" "1995" "22:10:43" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "59" "one question" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA10541; Mon, 27 Nov 95 20:39:56 PST Received: by maroon.tc.umn.edu; Mon, 27 Nov 95 22:10:45 -0600 In-Reply-To: <199511280128.RAA01699@wolfe.net> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817544315.006 From: Kevin C Houston To: rddesign@wolfenet.com Cc: Steve VanDevender , stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: one question Date: Mon, 27 Nov 1995 22:10:43 -0600 (CST) Steve, I have a question for you. (BTW, Your sarcasm on the reactionless drive was not lost on me. I am both overjoyed, and dismayed to have invented it overjoyed for obvious reasons. dismayed, because it cannot be --- although E E "Doc" Smith didn't think so ;) Out in intergalactic space (far far away from all outside gravitational influences) you have the following setup: black plate absorbs laser beam ^ p= E/C | _________ | : : | | : : | | :L: | | :A: | # - Laser source | :S: | : - Laser beam | :E: | | - wires to hold plates | :R: | | : : | | : : | | : : | | : : | | ### | | ### | | ### | --------- p= E/C | V The top plate (the absorber) is in thermal equilibrium with a large amount of solid Unobtainium m.p. 2.7 K, atomic mass = sqrt(-1) g/cm^3 so that there is no radiation from heat effects. power is provided by a small on-board power source What happens when you turn on the laser? I'd say that it would just sit there, although you can clearly see that without the wires to hold them together, the laser source and the top plate would to move away from each other. The wires are clearly dissipating a momentum equal to 2 E/C. that is what i was trying to say with my bb analogy. i do have an idea now for a reactionless drive. (inspired by your sarcastic post) It is late at night, and i must get some rest. i will have to post it on the web, as ascii art is not of sufficient resolution to describe it fully. I cannot see why it shouldn't work, Hopefully you will be able to explain. I'll let you all know when it's ready. Kevin H. From popserver Tue Nov 28 08:07:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["7164" "Tue" "28" "November" "1995" "09:05:22" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199511280805.AA25072@student.utwente.nl>" "160" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA19885; Tue, 28 Nov 95 00:04:11 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA25072 (5.67b/IDA-1.5 for ); Tue, 28 Nov 1995 09:05:15 +0100 Message-Id: <199511280805.AA25072@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817545868.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Tue, 28 Nov 1995 09:05:22 +0100 ReplyTo : Kelly ReplyFrom : Timothy >>> Externally fueled did that mean scooping? I'm not sure >>> anymore, please tell me if my assumption is right. > >Not quite. In my Exporer ship design I assumed the fusion fuel was launched >ahead of the ship with a linear accelerator. As the ship accelerates it >contiually scoops up pre launched fuel going at nearly its speed. So the >ship looses very little momentum scooping up the fuel packets. That would >allow you to get up to light speed with "only" 200 times the ships mas in >fusion fuel. However like Kevins system. We have a serious problem stoping. > I though using a ramscope to produce a lot of drag might do it, but never >found a good woorkup of the numbers. This method of prelaunching fuel packets will cost the same amount of energy that is needed if you take those same packets with you from the start. Why? Because all packets have the same speed as the Asimov after it has accelerated. Accelerating a lot of small packets or just one big packet does not save energy. >By the way. Did anyone calculate the drag on the sail structure from >interstelar debre? If you can maintain enough of an electric charge to use >the microwave sail as a parachute that might help with stoping. The problem is that there are no accurate numbers of the density of interstellar debris. So any number is almost a guess. =============================================================================== ReplyTo : Steve ReplyFrom : Timothy >In a frame where the ship is in motion, the photon changes energy >when it bounces off the ship; its reflected energy is less than >the incident energy if the ship receding, greater if the ship is >approaching. You actually were right to compare this to doppler >radar, because it's this effect that doppler radar measures to >determine velocity. Huh, are you saying I was right the first time? Am I right saying the following: Photons loose energy because they accelerate the car. Only because of that acceleration their frequency is lowered. Because it takes more energy to transfer the same amount of momentum to a faster moving car (E=v^2 versus p=v) the frequency is lowered even more. >Mass is a more subtle concept than energy; while energies add >linearly, masses as magnitudes of momenergy vectors do not. Agreed. > > I would conclude from this that moving bodies excert greater gravitation > > either because of gain of mass or gain of energy. I feel both can be used, > > its a bit like the wave-particle duality. > >What I really want to see is the general relativistic formula >that says whether spacetime curvature is the result of an >object's mass or its energy. It's hard to find such a formula, all books about general relativistics use tensor calculus. I have a hard time understanding them, so I don't know much about formulas in general relativistics. But don't think we need this formula any more: In Taylor & Wheelers terminology I think curvature would be the result of energy. In "more" general terms it would be either the result of its relativistic mass or the result of its rest mass AND its kinetic energy (ie. together the total energy). > > >> Is it this translation of energy to mass that gives the trouble? > > > > > >It is that my studies of relativistic kinematics do not allow for > > >the treatment of energy and mass as identical quantities. > > > > They are indeed not identical but equivalent, meaning they can be be > > interchanged. > >Not in Taylor and Wheeler's terminology. The only time they >allow mass and energy to be spoken of as equivalent is when you >are dealing with an object in its rest frame. In any other frame >the object's energy is not equivalent to its mass. No indeed not equivalent to its rest mass but equivalent to its relativistic mass. >>>> I say that "relativistic mass increase" is a misnomer and that >>>> you are better off treating mass as invariant. I guess that is what I always did, only I was not that much aware of the problems others might have with the duality in the terminology. After all this, can we conclude a charged battery is heavier than an uncharged battery? ================================================================================ ReplyTo : Kelly ReplyFrom : Timothy >Question. >Diverted beams of photons converge on a forward pointing cone. This (not >considering the beam cancelation due to interfearence, reflection loses, and >other such nonsence) is the origional beam moving forward in a much more >concentrated form than its pre sail moments. Net thrust to the ship near zip >(give or take). In frount of this stream we put an ionized reaction mass. > Beam slams into it and throws it forward. > >A) A lot of the beam (most?) would reflect back off the ionized reaction mass >(micro-waves do that off ionized matter) Would this act as Forward's >sacrificial outer-sail in "Dragons egg (?)"? I.E. could we use the forwardly >reflected beam for drive power? Efectivly the reaction mass (now renamed >plasma reflection mass) has gotten boosted forward at a hellish speed, but >bounced the beam back down our throats. (Just like Forwards outer drop >sail.) We would have to continuously replenish this "reflection mass", but >on the bright side we could be very sure it will clean all the interstellar >mass out from in frount of the ship. ;) Replenishing the "mirror" will probably take lots of ions or in other words mass that has to be taken with us. Also using such a light (non heavy) sail will mean that the "mirror" is accelerated a lot and lot of energy is lost due to the Doppler effect. Also I have doubts how well the "mirror" reflects, ionized particles attract or repell each other so, it won't take long befor the "mirror" has destroyed itself. >B) >Instead of just dumping this superheated reflect mass forward. How about >using it as a rocket stream also. At the least we can ride the expanding >shock wave from the stuff. Shock wave? I don't understand, please explain again. >Anyway, between A & B we have used part of the beam to create a high temp >plasma thurst, and reflected the rest off said plasma onto a rearwardly >reflective part of the ship. Momentum/kinetic energy interactions between >the beam and the ship are pretty much canceled out until it hits the >reaction/reflection mass. The ship needs NO POWER CONVERTERS! We never >convert it to electricity to drive an accelerator. (Ok, ok, we convert a >little to run the ship and power the magnetic feilds that keep the plasma off >the back of the ship.) But other than that, we just reflect it around and >feed it mass. ============================================================================== Steve writes: >The reality that static stress does not continue to dissipate >energy over time is not intuitive, because our muscles aren't >static structures like boards or rods or wires; they must >dissipate energy even to hold a weight motionless above your >head, while a table holding the same weight does not dissipate >energy. Yes, in fact is does not take any energy to keep floating a few metres above Earth's surface. Timothy From popserver Tue Nov 28 12:11:34 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2934" "Tue" "28" "November" "1995" "00:52:06" "-0800" "Steve VanDevender" "stevev@efn.org" nil "67" "one question" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA03323; Tue, 28 Nov 95 04:07:37 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id AAA19367; Tue, 28 Nov 1995 00:52:06 -0800 Message-Id: <199511280852.AAA19367@tzadkiel.efn.org> In-Reply-To: References: <199511280128.RAA01699@wolfe.net> X-UIDL: 817560468.008 From: Steve VanDevender To: Kevin C Houston Cc: rddesign@wolfenet.com, Steve VanDevender , T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: one question Date: Tue, 28 Nov 1995 00:52:06 -0800 Kevin C. Houston writes: > Steve, I have a question for you. (BTW, Your sarcasm on the > reactionless drive was not lost on me. I am both overjoyed, and dismayed > to have invented it overjoyed for obvious reasons. dismayed, because it > cannot be --- although E E "Doc" Smith didn't think so ;) I hope it did not seem harsh. My intent was to demonstrate a really nifty application for your, um, incredible invention. :-) > Out in intergalactic space (far far away from all outside gravitational > influences) you have the following setup: [ Figure turned sideways for brevity -- top -> ] |--------------------------------------| |######~~~~~~~~~~~~~~~~~~~~~~~~ | p = -E/c |######~~~~~L~A~S~E~R~~~~~~~~~~ | p = E/c |######~~~~~~~~~~~~~~~~~~~~~~~~ | |--------------------------------------| black plate absorbs laser beam # = laser ~ = laser beam - = support wires > The top plate (the absorber) is in thermal equilibrium with a large > amount of solid Unobtainium m.p. 2.7 K, atomic mass = sqrt(-1) g/cm^3 > so that there is no radiation from heat effects. power is provided by a > small on-board power source You must shop at the same physics experiment supply store that I do. That unobtainium sure is useful :-). > What happens when you turn on the laser? > > I'd say that it would just sit there, although you can clearly see that > without the wires to hold them together, the laser source and the top > plate would to move away from each other. You are correct. Although an actual device like this would actually move, but not with any permanent velocity. As the laser heats the absorption plate, mass is transferred from the laser to the plate. As the center of gravity shifts to the right (in my diagram) the assembly would slide to the left. When the laser is turned off, it would stop, then begin to slide slowly rightward as the plate reheats the laser by radiation. > The wires are clearly dissipating a momentum equal to 2 E/C. > that is what i was trying to say with my bb analogy. I'm not sure "dissipating momentum" is quite the term for it. After all, the laser with momentum -E/c is tugging through the wires against the plate with momentum E/c. The momenta cancel. Like I said before, momentum means motion. A non-moving object has no momentum. If the laser and the plate are held together with wires and don't move relative to each other or your observer, then you can't say that they have momentum. The wires are indeed under tension, because there is a force between the laser and the plate. This tension was created in the first instant the laser was turned on, and a small amount of its energy went into stretching the wires before it was all spent on heating the plate. From popserver Tue Nov 28 15:55:30 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["3150" "Tue" "28" "November" "1995" "09:04:41" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "86" "Re: one question" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA09333; Tue, 28 Nov 95 07:02:46 PST Received: by maroon.tc.umn.edu; Tue, 28 Nov 95 09:04:42 -0600 In-Reply-To: <199511280852.AAA19367@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817573904.011 From: Kevin C Houston To: Steve VanDevender Cc: rddesign@wolfenet.com, Steve VanDevender , T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: one question Date: Tue, 28 Nov 1995 09:04:41 -0600 (CST) On Tue, 28 Nov 1995, Steve VanDevender wrote: > Kevin C. Houston writes: > > > Out in intergalactic space (far far away from all outside gravitational > > influences) you have the following setup: > > [ Figure turned sideways for brevity -- top -> ] Fine with me. > > > |--------------------------------------| > |######~~~~~~~~~~~~~~~~~~~~~~~~ | > p = -E/c |######~~~~~L~A~S~E~R~~~~~~~~~~ | p = E/c > |######~~~~~~~~~~~~~~~~~~~~~~~~ | > |--------------------------------------| > black plate > absorbs laser beam > # = laser > ~ = laser beam > - = support wires > > > The top plate (the absorber) is in thermal equilibrium with a large > > amount of solid Unobtainium m.p. 2.7 K, atomic mass = sqrt(-1) g/cm^3 > > so that there is no radiation from heat effects. power is provided by a > > small on-board power source > > You must shop at the same physics experiment supply store that I > do. That unobtainium sure is useful :-). > > > What happens when you turn on the laser? > > > > I'd say that it would just sit there, although you can clearly see that > > without the wires to hold them together, the laser source and the top > > plate would to move away from each other. > > You are correct. > > Although an actual device like this would actually move, but not > with any permanent velocity. As the laser heats the absorption that's the reson for the unobtainium, the melting never shifts above cosmic backround radiation level > plate, mass is transferred from the laser to the plate. As the > center of gravity shifts to the right (in my diagram) the > assembly would slide to the left. When the laser is turned off, > it would stop, then begin to slide slowly rightward as the plate > reheats the laser by radiation. > > > The wires are clearly dissipating a momentum equal to 2 E/C. > > that is what i was trying to say with my bb analogy. > > I'm not sure "dissipating momentum" is quite the term for it. > After all, the laser with momentum -E/c is tugging through the > wires against the plate with momentum E/c. The momenta cancel. > YES! That's what I've been saying all along! that a physical structure can transmit (through tugging) opposite momenta that can then cancel! > Like I said before, momentum means motion. A non-moving object > has no momentum. If the laser and the plate are held together > with wires and don't move relative to each other or your > observer, then you can't say that they have momentum. The laser imparts momentum when it leaves, and when it strikes the black plate. > > The wires are indeed under tension, because there is a force > between the laser and the plate. This tension was created in the > first instant the laser was turned on, and a small amount of its > energy went into stretching the wires before it was all spent on > heating the plate. > so you're saying that the plate heats more if it is held in place than if it was free to move? Kevin From popserver Tue Nov 28 22:13:51 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["444" "Tue" "28" "November" "1995" "18:09:43" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199511281709.AA18223@student.utwente.nl>" "9" "Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA15729; Tue, 28 Nov 95 09:08:23 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA18223 (5.67b/IDA-1.5 for ); Tue, 28 Nov 1995 18:09:39 +0100 Message-Id: <199511281709.AA18223@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817596604.006 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Physics store Date: Tue, 28 Nov 1995 18:09:43 +0100 Hey, Steve and Kevin can one of you give me the address of that special physics supply store? I can't find one in the yellow pages. I'd like to shop there and try to find an anti-gravity/anti-inertia device. Such a device would be most useful. No bulky engines, only small amounts of energy needed. Even high acceleration would not be a problem because our muscles would have the same strength but our bodies would have less inertia. Timothy From popserver Tue Nov 28 22:13:55 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["868" "Tue" "28" "November" "1995" "12:01:53" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "22" "Re: Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA18479; Tue, 28 Nov 95 10:03:09 PST Received: by maroon.tc.umn.edu; Tue, 28 Nov 95 12:01:54 -0600 In-Reply-To: <199511281709.AA18223@student.utwente.nl> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817596604.010 From: Kevin C Houston To: Timothy van der Linden Cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Physics store Date: Tue, 28 Nov 1995 12:01:53 -0600 (CST) On Tue, 28 Nov 1995, Timothy van der Linden wrote: > Hey, Steve and Kevin can one of you give me the address of that special > physics supply store? I can't find one in the yellow pages. I'd like to shop > there and try to find an anti-gravity/anti-inertia device. > Such a device would be most useful. No bulky engines, only small amounts of > energy needed. Even high acceleration would not be a problem because our > muscles would have the same strength but our bodies would have less inertia. > > Timothy > > Sure, no problem. I can't remember the exact address, but the directions are easy enough. Go down to the nearest corner. Take any street to be direction 'x', take the perpendicular street to be 'y', take the vertical direction to be 'z', now go two blocks in any direction that is perpendicular to 'x','y' _and_ 'z'. you can't miss it. %^) From popserver Tue Nov 28 22:14:00 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["540" "" "28" "November" "1995" "13:56:20" "-0500" "jim@bogie2.bio.purdue.edu" "jim@bogie2.bio.purdue.edu" nil "17" "Re(2) Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from sage.cc.purdue.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA22151; Tue, 28 Nov 95 11:01:09 PST Received: from bogie2.bio.purdue.edu (bogie2.bio.purdue.edu [128.210.65.16]) by sage.cc.purdue.edu (8.6.10/8.6.12) with SMTP id NAA29371; Tue, 28 Nov 1995 13:53:48 -0500 Message-Id: X-UIDL: 817596604.013 From: "jim" To: "KellySt@aol.com" , "Kevin C Houston" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "Timothy van der Linden" , "zkulpa@zmit1.ippt.gov.pl" Subject: Re(2) Physics store Date: 28 Nov 1995 13:56:20 -0500 I believe you mean "Acme Physics Warehouse". There are several, but this has the personal endorsement of Mr. Wile E. Coyote (Super-Genius). In addition to anti-gravity generators, they also do good a business in massless ropes, frictionless pulleys, and infinate lines and planes of charge. Kevin's directions were a bit incomplete, however. The address is as follows: Acme Physics Warehouse Box 3.14 Squared Circle Phone Number : (278) 182-8182 ext. 8 - Jim Cavera (Super-Genius) Sent with CTM PowerMail 1.0 From popserver Tue Nov 28 23:04:48 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4801" "Tue" "28" "November" "1995" "15:00:18" "-0800" "Steve VanDevender" "stevev@efn.org" nil "102" "Re: one question" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA07848; Tue, 28 Nov 95 14:56:53 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id PAA21239; Tue, 28 Nov 1995 15:00:18 -0800 Message-Id: <199511282300.PAA21239@tzadkiel.efn.org> In-Reply-To: References: <199511280852.AAA19367@tzadkiel.efn.org> X-UIDL: 817599675.000 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: one question Date: Tue, 28 Nov 1995 15:00:18 -0800 Kevin C. Houston writes: > > > The wires are clearly dissipating a momentum equal to 2 E/C. > > > that is what i was trying to say with my bb analogy. > > > > I'm not sure "dissipating momentum" is quite the term for it. > > After all, the laser with momentum -E/c is tugging through the > > wires against the plate with momentum E/c. The momenta cancel. > > YES! That's what I've been saying all along! that a physical structure > can transmit (through tugging) opposite momenta that can then cancel! I thought about deleting that paragraph ("I'm not sure 'dissipating momentum' . . . ") because it's not really consistent with my position that you only have momentum if you have motion. If the things don't move, they don't have momentum, or absorb momentum, or dissipate momentum. What I was really objecting to in your parasail design was not the idea that you had cancelling momenta, but that you thought that creating sideways momentum meant a decrease in forward momentum. For example, a device like this: E/c --v :::: p = [ 0 E/(2*c) ] |----------------------------------:::/| |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::/ | |######~~~~~L~A~S~E~R~~~~~~~~~~~~~~:/ | beam splitter |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~:\ | |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::\ | |----------------------------------:::\| :::: p = [ 0 -E/(2*c) ] # = laser ~ = laser light -- = wires also won't move. The beam splitter "absorbs momentum" just like the black absorbing plate did, even though it splits the beam into two beams traveling in the +y and -y directions. This setup also has the advantage of not requiring an unobtainium heat sink, as long as you get a Perfect Mirror (tm) from Acme Physics Warehouse. Without wires to hold the beam splitter in a fixed position with respect to the laser, it too would move away from the laser. It's critical to understand that momentum is a vector quantity to understand how the beam splitter can move, even though it is emitting two beams whose momentum magnitudes are both p/2 while it is picking up momentum with magnitude p from the laser. Although it is intuitive to think in terms of the magnitudes of the momentum components and then try to add those to account for system momentum, it's unfortunately wrong. Although the laser light carries momentum [ p 0 ] to the unbound beam splitter and the splitter, as a result of reflecting halves of the beam, produces two smaller beams with momentum [ 0 p/2 ] and [ 0 -p/2 ], those two beams add to momentum [ 0 0 ] -- they carry no forward momentum whatsoever; as a pair, they carry no momentum at all. Yet conservation of momentum requires that the total momentum remain [ p 0 ], and the only place this can show up is in the beam splitter itself. Since the beam splitter stopped all forward motion of the beam, it's not even that unintuitive that it should get the forward momentum. The ultimate case of absolutely needing to think of momentum as a vector quantity is when you have an object with zero momentum that splits into two or more objects with nonzero momenta. The vector sum of momenta of all the objects will still be zero, but in a sense momentum did come from nowhere since an unmoving object gave rise to motion. > > Like I said before, momentum means motion. A non-moving object > > has no momentum. If the laser and the plate are held together > > with wires and don't move relative to each other or your > > observer, then you can't say that they have momentum. > > The laser imparts momentum when it leaves, and when it strikes the black > plate. Once, during the time that the beam is in progress to the absrber plate. For much the same reasons that I don't like "relativistic mass", I don't like the notion of imparting momentum to a non-moving object. Clearly it has lead to some incorrect physical thinking. If something can't be put into uniform linear motion relative to something else, then it can't "absorb momentum" relative to that thing. > > The wires are indeed under tension, because there is a force > > between the laser and the plate. This tension was created in the > > first instant the laser was turned on, and a small amount of its > > energy went into stretching the wires before it was all spent on > > heating the plate. > > so you're saying that the plate heats more if it is held in place than if > it was free to move? Yes. If it was free to move, it would acquire velocity; as it acquired velocity, the light it received would become weaker due to doppler-shifting, and so the plate would receive less energy. If it is held in place, then it never has velocity relative to the laser, which always transmits the same energy per unit time to the plate. From popserver Tue Nov 28 23:30:10 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1319" "Tue" "28" "November" "1995" "15:28:18" "-0800" "Steve VanDevender" "stevev@efn.org" nil "25" "Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA09692; Tue, 28 Nov 95 15:24:51 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id PAA21310; Tue, 28 Nov 1995 15:28:18 -0800 Message-Id: <199511282328.PAA21310@tzadkiel.efn.org> In-Reply-To: <199511281709.AA18223@student.utwente.nl> References: <199511281709.AA18223@student.utwente.nl> X-UIDL: 817601196.000 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Physics store Date: Tue, 28 Nov 1995 15:28:18 -0800 Timothy van der Linden writes: > Hey, Steve and Kevin can one of you give me the address of that special > physics supply store? I can't find one in the yellow pages. I'd like to shop > there and try to find an anti-gravity/anti-inertia device. > Such a device would be most useful. No bulky engines, only small amounts of > energy needed. Even high acceleration would not be a problem because our > muscles would have the same strength but our bodies would have less inertia. > > Timothy Others have given you the address of the Acme Physics Warehouse. The stuff you want is probably in the "Cartoon Physics" section; the "Real Physics" section just has stuff like point masses, frictionless surface coatings, and ideal gases. You can do antigravity in several ways. One is to keep a suspended creature permanently in ignorance of its altitude with special blinders; as you know, creatures won't fall until they know they are above a canyon. Another is to surprise a creature, causing it to levitate above the ground, then keep it in that state; you can get boxes of carefully bred mice that are easily surprised. Someone in love will float above the ground, and can be tugged around simply by the scent of the loved one, implying minimal inertia; tailored "love drugs" can be used to induce this state. From popserver Tue Nov 28 23:50:36 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1860" "Tue" "28" "November" "1995" "15:47:04" "-0800" "Steve VanDevender" "stevev@efn.org" nil "43" "Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA10985; Tue, 28 Nov 95 15:43:37 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id PAA21352; Tue, 28 Nov 1995 15:47:04 -0800 Message-Id: <199511282347.PAA21352@tzadkiel.efn.org> In-Reply-To: <199511280805.AA25072@student.utwente.nl> References: <199511280805.AA25072@student.utwente.nl> X-UIDL: 817602415.000 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Tue, 28 Nov 1995 15:47:04 -0800 Timothy van der Linden writes: > Am I right saying the following: > > Photons loose energy because they accelerate the car. Only because of that > acceleration their frequency is lowered. > Because it takes more energy to transfer the same amount of momentum to a > faster moving car (E=v^2 versus p=v) the frequency is lowered even more. There is one important constraint in this situation: photons _always_ have equal momentum and energy; hence a photon reflecting off a moving object must impart equal amounts of momentum and energy to it. A photon has less energy when seen from the frame of a fast-moving object moving in the same direction as the photon, so in the object frame the photon imparts less momentum to the object. Seen from the observer's frame, the photon loses more momentum to a receding fast-moving object than a slow-moving one. Remember that reflecting objects moving opposite to the direction of the incident photons actually impart energy and momentum to the photons; in the object frame the photon has more energy and momentum. > After all this, can we conclude a charged battery is heavier than an > uncharged battery? Yes, this is also true. Hot objects are heavier than cold ones (although not by an amount we have equipment to measure). A mirrored box full of photons is heavier than the empty box. > Steve writes: > >The reality that static stress does not continue to dissipate > >energy over time is not intuitive, because our muscles aren't > >static structures like boards or rods or wires; they must > >dissipate energy even to hold a weight motionless above your > >head, while a table holding the same weight does not dissipate > >energy. > > Yes, in fact is does not take any energy to keep floating a few metres above > Earth's surface. Well, it depends on how you make the object float. From popserver Wed Nov 29 00:00:51 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["512" "Wed" "29" "November" "1995" "00:56:57" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "12" "Re: Re(2) Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA11563; Tue, 28 Nov 95 15:54:14 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA15487 (5.67b/IDA-1.5 for ); Wed, 29 Nov 1995 00:56:53 +0100 Message-Id: <199511282356.AA15487@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817603036.001 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Re(2) Physics store Date: Wed, 29 Nov 1995 00:56:57 +0100 Steve, I had a hard time figuring out where to go, fortunately Jim's message reached me before I got lost completely. I talked to Mr. Wile and asked him for the anti-grav. equipment. He told me somebody had been there before me, just one hour earlier and bought the last one. He already had ordered new ones but did not know yet when they would arrive. It was possible to reserve one, so I did. I almost can't wait untill I can use it. When I have got equipment, I will tell you guys more about it... Timothy From popserver Wed Nov 29 05:52:10 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["1536" "Tue" "28" "November" "1995" "20:38:55" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951128203350_119181713@emout06.mail.aol.com>" "33" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA17882; Tue, 28 Nov 95 17:37:25 PST Received: by emout06.mail.aol.com (8.6.12/8.6.12) id UAA24591; Tue, 28 Nov 1995 20:38:55 -0500 Message-Id: <951128203350_119181713@emout06.mail.aol.com> X-UIDL: 817624104.001 From: KellySt@aol.com To: stevev@efn.org Cc: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Tue, 28 Nov 1995 20:38:55 -0500 >> Besides not treating momentum as a vector quantity, people are >> making the mistake of thinking that lateral loading of the sail >> assembly is a magical sink for momentum or energy. The error is >> in thinking that stress on a static structure absorbs energy or >> momentum continuously over time. If the sail does not move >> relative to the ship, then it cannot absorb or dissipate momentum >> separately from the ship. It cannot absorb momentum if it does >> not move, because momentum means motion. ---- (??!) Thats like the old argument that if a tractor is pushing against a wall its doing no work, since the wall isn't accelerated. The sail is getting a thrust that is perpendicular to the surface of reflection. If you want to describe the portion of the thrust that isn't accelerating the ship as invalid, enjoy. But when you start to mutter things like: >> ---as long as the sail does not fall apart or the support >> members do not break, no more energy is dissipated into >> loading of the sail structure. We have a problem. A considerable amount of energy will be continuously loaded and (hopefully) disapated by the sail cross webbing. If we don't consider it, and make sure the structure can disapate it, the cross cables will melt under the energy they have to disapate under this lateral thrust load. One very consistent problem in LIT over the last year has been a very limited interest in the engineering realities of a situation, and to much fondness for endless equation wars. Kelly From popserver Wed Nov 29 05:52:32 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["467" "Tue" "28" "November" "1995" "21:52:43" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "13" "Re: Re(2) Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA21876; Tue, 28 Nov 95 18:50:36 PST Received: by emout04.mail.aol.com (8.6.12/8.6.12) id VAA13914; Tue, 28 Nov 1995 21:52:43 -0500 Message-Id: <951128215241_37461372@emout04.mail.aol.com> X-UIDL: 817624104.012 From: KellySt@aol.com To: jim@bogie2.bio.purdue.edu, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, zkulpa@zmit1.ippt.gov.pl Subject: Re: Re(2) Physics store Date: Tue, 28 Nov 1995 21:52:43 -0500 >> I believe you mean "Acme Physics Warehouse". There are >> several, but this has the personal endorsement of Mr. >> Wile E. Coyote (Super-Genius). In addition to >> anti-gravity generators, they also do good a business in >> massless ropes, frictionless pulleys, and infinate lines >> and planes of charge. >> - Jim Cavera (Super-Genius) Hum -- If they have used hydrive, or some of the Star Trek gobbdy gook physics we're in busness!! ;) Kelly Starks From popserver Wed Nov 29 05:52:33 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6330" "Tue" "28" "November" "1995" "21:52:07" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "140" "Re: Engineering Newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail02.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA21944; Tue, 28 Nov 95 18:51:41 PST Received: by mail02.mail.aol.com (8.6.12/8.6.12) id VAA02539; Tue, 28 Nov 1995 21:52:07 -0500 Message-Id: <951128215138_37459926@mail02.mail.aol.com> X-UIDL: 817624104.013 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 28 Nov 1995 21:52:07 -0500 Replyto : Timothy >>> Externally fueled did that mean scooping? I'm not sure >>> anymore, please tell me if my assumption is right. > >Not quite. In my Exporer ship design I assumed the fusion fuel was launched >ahead of the ship with a linear accelerator. As the ship accelerates it >contiually scoops up pre launched fuel going at nearly its speed. So the >ship looses very little momentum scooping up the fuel packets. That would >allow you to get up to light speed with "only" 200 times the ships mas in >fusion fuel. However like Kevins system. We have a serious problem stoping. > I though using a ramscope to produce a lot of drag might do it, but never >found a good woorkup of the numbers. >> This method of prelaunching fuel packets will cost the >> same amount of energy that is needed if you take those >> same packets with you from the start. True, but since the ship doesn't have to supply the energy, it saves an incredable amount of fuel. To put it bluntly no fusion powered ship could carry enough fuel, to accelerate itself and its fuel up to high reletivistic speeds. Estimates are that a ship would need a 1,000,000 to 1 fuel to ship mass ratio to get up to $10 of light speed. But if the ship doesn't have to carry its fuel, a 200 to 1 ratio could get you most of the way to light speed (or was that 1/3rd light speed. Been a while since GES ran the numbers off for me.) >By the way. Did anyone calculate the drag on the sail structure from >interstelar debre? If you can maintain enough of an electric charge to use >the microwave sail as a parachute that might help with stoping. >> The problem is that there are no accurate numbers of >> the density of interstellar debris. So any number is almost >> a guess. Thats been a constand problem for us. How do you design a ship to travel through something you know next to nothing about? ============================================================================== == >Question. >Diverted beams of photons converge on a forward pointing cone. This (not >considering the beam cancelation due to interfearence, reflection loses, and >other such nonsence) is the origional beam moving forward in a much more >concentrated form than its pre sail moments. Net thrust to the ship near zip >(give or take). In frount of this stream we put an ionized reaction mass. > Beam slams into it and throws it forward. > >A) A lot of the beam (most?) would reflect back off the ionized reaction mass >(micro-waves do that off ionized matter) Would this act as Forward's >sacrificial outer-sail in "Dragons egg (?)"? I.E. could we use the forwardly >reflected beam for drive power? Efectivly the reaction mass (now renamed >plasma reflection mass) has gotten boosted forward at a hellish speed, but >bounced the beam back down our throats. (Just like Forwards outer drop >sail.) We would have to continuously replenish this "reflection mass", but >on the bright side we could be very sure it will clean all the interstellar >mass out from in frount of the ship. ;) >> Replenishing the "mirror" will probably take lots of ions >> or in other words mass that has to be taken with us. Agreed, but it don't have a handel on the amount of mass. (Hey it sounds better than Forwards ring sail trick.) >> Also using such a light (non heavy) sail will mean that >> the "mirror" is accelerated a lot and lot of energy is lost >> due to the Doppler effect. Given that the mirror is the surface of a plasma, and said plasma is being continuously being replenished. I'm not sure the reflective "surface" is actually moving? Althou obviously the particals in the plasma are moving (and accelerating) rapidly. Are the micro waves reflecting off the particals? Or off the area where the plasma is ionized enough to reflect them? >> Also I have doubts how well the "mirror" reflects, ionized >> particles attract or repell each other so, it won't take long >> befor the "mirror" has destroyed itself. The ions in a plasma of the same material wil repell each other. You might be able to do some magnetic tricks to hold it, but it probably wouldn't be worth the trouble. [ Hum --- I wounder if you could wiggle the exausting plasma to for a laser to get back some of the energy? ] As to reflectivity. That would depend on the nature of the plasma and a lot of other variables. This is probably not a question we could easily figure out for ourselves. >B) >Instead of just dumping this superheated reflect mass forward. How about >using it as a rocket stream also. At the least we can ride the expanding >shock wave from the stuff. >> Shock wave? I don't understand, please explain again. You have a mass of plasma being hit with E18 of energy. It will be HOT, and highly ionized. It will be explosivly expanding. The light pressure of the beam (or the feed mass) will probably keep it from flowing straight up the beam. But it will be moving rapidly to the sides and forward or the ship. We should be able to tap this for thrust. >Anyway, between A & B we have used part of the beam to create a high temp >plasma thurst, and reflected the rest off said plasma onto a rearwardly >reflective part of the ship. Momentum/kinetic energy interactions between >the beam and the ship are pretty much canceled out until it hits the >reaction/reflection mass. The ship needs NO POWER CONVERTERS! We never >convert it to electricity to drive an accelerator. (Ok, ok, we convert a >little to run the ship and power the magnetic feilds that keep the plasma off >the back of the ship.) But other than that, we just reflect it around and >feed it mass. ============================================================================== Steve writes: >The reality that static stress does not continue to dissipate >energy over time is not intuitive, because our muscles aren't >static structures like boards or rods or wires; they must >dissipate energy even to hold a weight motionless above your >head, while a table holding the same weight does not dissipate >energy. >> Yes, in fact is does not take any energy to keep floating a >> few metres above Earth's surface. (???????!!!!!!) SAY WHAT!! Unless we're on differnt planets you have to generate or disapate as much energy as to generate 9.8 m/s^2 of acceleration. Kelly Starks From popserver Wed Nov 29 05:52:36 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["451" "Tue" "28" "November" "1995" "21:52:58" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "14" "Re: Physics store" "^From:" nil nil "11" nil nil nil nil] nil) Received: from emout04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA22018; Tue, 28 Nov 95 18:52:51 PST Received: by emout04.mail.aol.com (8.6.12/8.6.12) id VAA14173; Tue, 28 Nov 1995 21:52:58 -0500 Message-Id: <951128215251_37461691@emout04.mail.aol.com> X-UIDL: 817624104.014 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl Cc: stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Physics store Date: Tue, 28 Nov 1995 21:52:58 -0500 >> I can't remember the exact address, but the directions >> are easy enough. >> Go down to the nearest corner. Take any street to be >> direction 'x', take the perpendicular street to be 'y', take >> the vertical direction to be 'z', now go two blocks in any >> direction that is perpendicular to 'x','y' _and_ 'z'. you >> can't miss it. %^) {:}-( Kev, I think your finals are starting to get to you. You need to lie down for a while! From popserver Wed Nov 29 05:52:37 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["1035" "Tue" "28" "November" "1995" "21:52:14" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951128215159_37460474@mail02.mail.aol.com>" "27" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from mail02.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA21916; Tue, 28 Nov 95 18:53:21 PST Received: by mail02.mail.aol.com (8.6.12/8.6.12) id VAA02638; Tue, 28 Nov 1995 21:52:14 -0500 Message-Id: <951128215159_37460474@mail02.mail.aol.com> X-UIDL: 817624104.015 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org Cc: T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Tue, 28 Nov 1995 21:52:14 -0500 On Mon, 27 Nov 1995, Steve VanDevender wrote: > Kevin C. Houston writes: > > the "momentum" happens every second, so it's actually an acelleration. > > That won't get you out of conservation of momentum. The system > must change momentum per unit time to equal the amount of > momentum added per unit time. > > > many structures (static tho they be) resist continuous acceleration all > > the time by providing opposing compressive or tensile forces > > The opposing forces are some finite amount of energy that is > loaded into the system once. Once the structure is loaded it > does not absorb any more energy. > > If a static structure had to dissipate energy continuously to > remain standing, where would such energy come from? Why doesn't > your house fall down? Where are the batteries? The energy is coming from the gravitational attraction of the earth. It is disapated as heat in the structure of the house. In a structure under heavy loads (too heavy) you can feel the heat in the structure. Kelly Starks From popserver Wed Nov 29 06:03:14 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["680" "Tue" "28" "November" "1995" "22:00:49" "-0800" "Steve VanDevender" "stevev@efn.org" nil "16" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA02264; Tue, 28 Nov 95 21:57:21 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id WAA00313; Tue, 28 Nov 1995 22:00:49 -0800 Message-Id: <199511290600.WAA00313@tzadkiel.efn.org> In-Reply-To: <951128215159_37460474@mail02.mail.aol.com> References: <951128215159_37460474@mail02.mail.aol.com> X-UIDL: 817624769.000 From: Steve VanDevender To: KellySt@aol.com Cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Tue, 28 Nov 1995 22:00:49 -0800 KellySt@aol.com writes: > > If a static structure had to dissipate energy continuously to > > remain standing, where would such energy come from? Why doesn't > > your house fall down? Where are the batteries? > > The energy is coming from the gravitational attraction of the earth. It is > disapated as heat in the structure of the house. In a structure under heavy > loads (too heavy) you can feel the heat in the structure. Really? So when does the earth run out of gravity? I think you've spent too much time in the Cartoon Physics section of Acme Physics Warehouse. Tell me about one of these structures that I can go visit, put my hand on, and feel the heat. From popserver Wed Nov 29 21:34:24 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3975" "Wed" "29" "November" "1995" "11:36:38" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "102" "Re: one question" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA14433; Wed, 29 Nov 95 02:33:53 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA17411 (5.67b/IDA-1.5 for ); Wed, 29 Nov 1995 11:36:33 +0100 Message-Id: <199511291036.AA17411@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817680631.001 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: one question Date: Wed, 29 Nov 1995 11:36:38 +0100 To: Steve and Kevin >For much the same reasons that I don't like "relativistic mass", >I don't like the notion of imparting momentum to a non-moving >object. Clearly it has lead to some incorrect physical >thinking. If something can't be put into uniform linear motion >relative to something else, then it can't "absorb momentum" >relative to that thing. While for relativistic mass there is just a different word for the same thing, there is in this case no other word. The word that here is invented is "imparted momentum" which should replaced by the word "energy". Timothy ------------------------------------------------------------------------------- Subject: Physics store >Others have given you the address of the Acme Physics Warehouse. >The stuff you want is probably in the "Cartoon Physics" section; >the "Real Physics" section just has stuff like point masses, >frictionless surface coatings, and ideal gases. I'm not sure, that unobtanium with its negative mass seemed to come from the same store. But if you are right, then that Wile guy has lied to me and probably is on the run with my down payment. :( >You can do antigravity in several ways. One is to keep a >suspended creature permanently in ignorance of its altitude with >special blinders; as you know, creatures won't fall until they >know they are above a canyon. Another is to surprise a creature, >causing it to levitate above the ground, then keep it in that >state; you can get boxes of carefully bred mice that are easily >surprised. Someone in love will float above the ground, and can >be tugged around simply by the scent of the loved one, implying >minimal inertia; tailored "love drugs" can be used to induce this >state. All these examples seem to have some mental control mechanism. That probably means that I have to do a lot of yoga lessons first. Timothy ------------------------------------------------------------------------------- To: Steve >There is one important constraint in this situation: photons >_always_ have equal momentum and energy; hence a photon >reflecting off a moving object must impart equal amounts of >momentum and energy to it. Yes, I was aware of that: U = p c >A photon has less energy when seen from the frame of a >fast-moving object moving in the same direction as the photon, so >in the object frame the photon imparts less momentum to the >object. Seen from the observer's frame, the photon loses more >momentum to a receding fast-moving object than a slow-moving one. Indeed, that would make it right in all frames. >Remember that reflecting objects moving opposite to the direction >of the incident photons actually impart energy and momentum to >the photons; in the object frame the photon has more energy and >momentum. Yes, because the moving observer would see a higher energy than an observer at rest. > > After all this, can we conclude a charged battery is heavier than an > > uncharged battery? > >Yes, this is also true. Hot objects are heavier than cold ones >(although not by an amount we have equipment to measure). A >mirrored box full of photons is heavier than the empty box. And it doesn't matter if they all move parallel and in the same direction all the time, right? Here is another one: If two particles feel the gravity of each other, then they are heavier together than if they are separate because of the extra gravitational energy. > > Yes, in fact is does not take any energy to keep floating a few metres above > > Earth's surface. > >Well, it depends on how you make the object float. No, if you for example use a helicopter, it does not take energy to stay at that height but it does take energy to move all the air. A true anti-gravity source would only have to build up a anti-gravity field once and does not use energy to stay at a certain heigh. If you use two magnets or two charged plates (both positive or negative) they also would not use any energy after you levitated. Timothy From popserver Thu Nov 30 08:27:17 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6897" "Thu" "30" "November" "1995" "09:21:50" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "172" "Engineering newsletter" "^From:" nil nil "11" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA25659; Thu, 30 Nov 95 00:19:01 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA24811 (5.67b/IDA-1.5 for ); Thu, 30 Nov 1995 09:21:43 +0100 Message-Id: <199511300821.AA24811@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817719805.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering newsletter Date: Thu, 30 Nov 1995 09:21:50 +0100 Bb accident, I mailed this letter only to Kelly yesterday. So here is it for the rest of you. Subject : (Star)Wars > > One very consistent problem in LIT over the last year has been > > a very limited interest in the engineering realities of a > > situation, and to much fondness for endless equation wars. > >These are not equation wars; as this message shows, you don't >always have to use math to talk about physics. We are talking >about very real physics concepts, and I'm afraid you are the one >who has a few important ones wrong. > >Before we can do the detailed engineering for a starship, we need >to understand what physical constraints it will be under. Even >the best engineering cannot violate the laws of physics. If we >are engaged in "equation wars", it is because we are trying to >figure out the limits of what is possible before we do detailed >design work based on faulty assumptions. This is the most >fundamental interest in engineering realities you could want. Steve, I've nothing to add, you're completely right. Timothy =============================================================================== ReplyTo : Kelly >From : Timothy Subject : Prelaunching >>> This method of prelaunching fuel packets will cost the >>> same amount of energy that is needed if you take those >>> same packets with you from the start. > >True, but since the ship doesn't have to supply the energy, it saves an >incredable amount of fuel. The ship does not have to supply the energy! It will leave fully fueled. It is still accelerated by some kind of photon beam. >To put it bluntly no fusion powered ship could >carry enough fuel, to accelerate itself and its fuel up to high reletivistic >speeds. Estimates are that a ship would need a 1,000,000 to 1 fuel to ship >mass ratio to get up to $10 of light speed. But if the ship doesn't have to >carry its fuel, a 200 to 1 ratio could get you most of the way to light speed >(or was that 1/3rd light speed. Been a while since GES ran the numbers off >for me.) Huh, if it doesn't carry its fuel, how do you calculate a ratio? !! Please be specific if you mean FUEL or REACTION MASS !! >>> The problem is that there are no accurate numbers of >>> the density of interstellar debris. So any number is almost >>> a guess. > >Thats been a constand problem for us. How do you design a ship to travel >through something you know next to nothing about? It would be best if we could find a solution without using the interstellar particles, but at the same time we should keep in mind that we have to protect us against it. This may sound a bit contradictory but a general solution would be best. =========================================================================== ReplyTo : Kelly >From : Timothy Subject : Plasma mirror >>> Replenishing the "mirror" will probably take lots of ions >>> or in other words mass that has to be taken with us. > >Agreed, but it don't have a handel on the amount of mass. Why doesn't it have to do with the amount of mass? Ions are particles too. They may have small masses, but if you have enough of them you could build a complete dragon-fly sail. >>> Also using such a light (non heavy) sail will mean that >>> the "mirror" is accelerated a lot and lot of energy is lost >>> due to the Doppler effect. > >Given that the mirror is the surface of a plasma, and said plasma is being >continuously being replenished. I'm not sure the reflective "surface" is >actually moving? Althou obviously the particals in the plasma are moving >(and accelerating) rapidly. Are the micro waves reflecting off the >particals? Or off the area where the plasma is ionized enough to reflect >them? Probably all the way in between. But that is not important here, because a reflection means transfer of momentum, and with it energy. Since the plasma will be accelerated a lot, it will retrieve a lot of energy. >>> Also I have doubts how well the "mirror" reflects, ionized >>> particles attract or repell each other so, it won't take long >>> befor the "mirror" has destroyed itself. > >The ions in a plasma of the same material wil repell each other. You might >be able to do some magnetic tricks to hold it, but it probably wouldn't be >worth the trouble. > >[ Hum --- I wounder if you could wiggle the exausting plasma to for a laser >to get back some of the energy? ] Don't talk about plasma as if it where some easy to control stuff. The movement of the plasma itself would create magnetic fields. It's like boiling water but much worse. >As to reflectivity. That would depend on the nature of the plasma and a lot >of other variables. This is probably not a question we could easily figure >out for ourselves. >>> Shock wave? I don't understand, please explain again. > >You have a mass of plasma being hit with E18 of energy. It will be HOT, and >highly ionized. It will be explosivly expanding. The light pressure of the >beam (or the feed mass) will probably keep it from flowing straight up the >beam. But it will be moving rapidly to the sides and forward or the ship. > We should be able to tap this for thrust. My guess is that this shock wave will move mostly forward instead of backward. You seem to want to do the same thing Kevin did: Make a easy thing complicated and so loose complete control over what you are doing. Whatever method you can think of, it will take just as much energy that the dragon-fly-sail will use. ============================================================================== ReplyTo : Kelly >From : Timothy Subject : Floating <> flying >>> Yes, in fact is does not take any energy to keep floating a >>> few metres above Earth's surface. > >(???????!!!!!!) SAY WHAT!! Unless we're on differnt planets you have to >generate or disapate as much energy as to generate 9.8 m/s^2 of acceleration. No, I wasn't in the Acme physics store... I refer to the answer I wrote to Steve about this same thing and add some formulas: F = m a U = F s = m a s P = U / t Where F=force, U=energy, m=mass, a=acceleration, s=distance_moved, t=time_needed In 4.3 seconds I will evenly pull a mass of 1.3 kg 2.6 metres up in Earth's g=9.8 m/s^2 That will take a force F=1.3*9.8=12.74 Newton and an amount of energy U=12.74*2.6=33.124 Joule and will take a power of P=33.124/4.3=7.703 Watt So if we are talking about weightlifting, there are several phases. First the weightlifter has to get the weight from the ground to up his head. That is where the real energy is needed, since there is a distance of movement involved. After he/she has lifted the weight and keeps it above his/her head the real work is done. All that the weightlifter has to do is keep his muscles in place. But that energy is not added to the weights. Often it is more difficult to get the weight up than to keep it there, that is just because of this reason. From popserver Fri Dec 1 21:18:52 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["671" "Fri" "1" "December" "1995" "12:23:58" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "16" "Too bad" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA12288; Fri, 1 Dec 95 03:21:07 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA22517 (5.67b/IDA-1.5 for ); Fri, 1 Dec 1995 12:23:47 +0100 Message-Id: <199512011123.AA22517@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 817852487.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Too bad Date: Fri, 01 Dec 1995 12:23:58 +0100 Here some great idea, but not really... Space is "filled" with the so called background radiation, right? What would happen to an object that has a perfect mirror on one side? Right, the mirror would reflect the background radiation. So this extra momentum at that one side would make the object move in the opposite direction. Wow, this makes movement easy, but not really... Since the background radiation is so small you would need enormous mirrors of light weight. Probably solar radiation over 10 ly. would work even better. So, too bad, if only the background radiation was about 500 Kelvin, but probably that would cook us all... OK, next time better. Timothy From popserver Fri Dec 1 21:18:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["1826" "Fri" "1" "December" "1995" "07:24:10" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "45" "Re: one question" "^From:" nil nil "12" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA14918; Fri, 1 Dec 95 05:21:56 PST Received: by maroon.tc.umn.edu; Fri, 1 Dec 95 07:24:11 -0600 In-Reply-To: <199511282300.PAA21239@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817852487.001 From: Kevin C Houston To: Steve VanDevender Cc: Steve VanDevender , rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: one question Date: Fri, 1 Dec 1995 07:24:10 -0600 (CST) On Tue, 28 Nov 1995, Steve VanDevender wrote: > What I was really objecting to in your parasail design was not > the idea that you had cancelling momenta, but that you thought > that creating sideways momentum meant a decrease in forward > momentum. For example, a device like this: > > > E/c --v :::: p = [ 0 E/(2*c) ] > |----------------------------------:::/| > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::/ | > |######~~~~~L~A~S~E~R~~~~~~~~~~~~~~:/ | beam splitter > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~:\ | > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::\ | > |----------------------------------:::\| > :::: p = [ 0 -E/(2*c) ] > > # = laser ~ = laser light -- = wires > > also won't move. The beam splitter "absorbs momentum" just like > the black absorbing plate did, even though it splits the beam > into two beams traveling in the +y and -y directions. This setup > also has the advantage of not requiring an unobtainium heat sink, > as long as you get a Perfect Mirror (tm) from Acme Physics > Warehouse. So you're saying that the beam splitter above would move at the same speed as a absorbtion plate of the same mass? > > > The wires are indeed under tension, because there is a force > > > between the laser and the plate. This tension was created in the > > > first instant the laser was turned on, and a small amount of its > > > energy went into stretching the wires before it was all spent on > > > heating the plate. > > I've always been taught to view atomic bonds as tiny springs which obey hookes law F=kx where k is some constant. this is the force that balances the force of the laser / absorber plate. Is this view correct? Doesn't a spring provide a constant force as long as it's stretched from it's initial position? From popserver Fri Dec 1 22:10:45 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2934" "Fri" "1" "December" "1995" "14:06:26" "-0800" "Steve VanDevender" "stevev@efn.org" nil "59" "Re: one question" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA14297; Fri, 1 Dec 95 14:02:40 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id OAA02463; Fri, 1 Dec 1995 14:06:26 -0800 Message-Id: <199512012206.OAA02463@tzadkiel.efn.org> In-Reply-To: References: <199511282300.PAA21239@tzadkiel.efn.org> X-UIDL: 817855596.001 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: one question Date: Fri, 1 Dec 1995 14:06:26 -0800 Kevin C. Houston writes: > > For example, a device like this: > > > > > > E/c --v :::: p = [ 0 E/(2*c) ] > > |----------------------------------:::/| > > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::/ | > > |######~~~~~L~A~S~E~R~~~~~~~~~~~~~~:/ | beam splitter > > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~:\ | > > |######~~~~~~~~~~~~~~~~~~~~~~~~~~~~::\ | > > |----------------------------------:::\| > > :::: p = [ 0 -E/(2*c) ] > > > > # = laser ~ = laser light -- = wires > > > > also won't move. The beam splitter "absorbs momentum" just like > > the black absorbing plate did, even though it splits the beam > > into two beams traveling in the +y and -y directions. This setup > > also has the advantage of not requiring an unobtainium heat sink, > > as long as you get a Perfect Mirror (tm) from Acme Physics > > Warehouse. > > So you're saying that the beam splitter above would move at the same > speed as a absorbtion plate of the same mass? It would get momentum p from a beam with momentum p just like the perfect absorber would. However, over time it would end up at a higher speed than the absorber because it does not increase in mass over time like the absorber does. The absorber develops momenergy [ m+p p 0 0 ] after absorbing photons with momenergy [ p p 0 0 ], so its mass increases to sqrt(m^2 + 2 * p * m) (if p << m, this approximates to m + p), while the beam splitter develops momenergy [ sqrt(m^2+p^2) p 0 0 ] from splitting the same beam because its mass remains a constant m. Hence the velocity of the absorber after absorbing light with momentum p is p / sqrt(m^2 + 2*p*m), while the velocity of the beam splitter is p / sqrt(m^2 + p^2). > > > > The wires are indeed under tension, because there is a force > > > > between the laser and the plate. This tension was created in the > > > > first instant the laser was turned on, and a small amount of its > > > > energy went into stretching the wires before it was all spent on > > > > heating the plate. > I've always been taught to view atomic bonds as tiny springs which obey > hookes law F=kx where k is some constant. this is the force that > balances the force of the laser / absorber plate. Is this view correct? > Doesn't a spring provide a constant force as long as it's stretched from > it's initial position? Note that F = k * x means that the force varies linearly with displacement, so increasing displacement means increasing force. A spring provides constant force as long as it remains stretched the same amount. This may be what you meant above, but you don't seem to make the distinction that the spring force varies with displacement. F = k * x is approximately correct for "ideal" springs and small displacements and may be valid for normal materials under small amounts of tension or compression; I don't know for sure. From popserver Sun Dec 3 01:21:14 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["4714" "Sat" "2" "December" "1995" "20:07:37" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951202200736_42256412@emout05.mail.aol.com>" "119" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "12" nil nil nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA15503; Sat, 2 Dec 95 17:05:09 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id UAA15378; Sat, 2 Dec 1995 20:07:37 -0500 Message-Id: <951202200736_42256412@emout05.mail.aol.com> X-UIDL: 817953394.014 From: KellySt@aol.com To: stevev@efn.org Cc: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Sat, 2 Dec 1995 20:07:37 -0500 to: stevev@efn.org > > If a static structure had to dissipate energy continuously to > > remain standing, where would such energy come from? Why doesn't > > your house fall down? Where are the batteries? > > The energy is coming from the gravitational attraction of the earth. It is > disapated as heat in the structure of the house. In a structure under heavy > loads (too heavy) you can feel the heat in the structure. Steve>> Really? So when does the earth run out of gravity? When space gets tired of curving? ;) Steve>> I think you've spent too much time in the Cartoon Steve>> Physics section of Acme Physics Warehouse. Steve>> Tell me about one of these structures that I can go Steve>> visit, put my hand on, and feel the heat. Over stressed cable stayed structures are about the only ones I've delt with that I could feel the differnce in. Others are too low to feel, but insterments can detect it. ======================================================== : stevev@efn.org KellySt@aol.com writes: > >> Besides not treating momentum as a vector quantity, people are > >> making the mistake of thinking that lateral loading of the sail > >> assembly is a magical sink for momentum or energy. The error is > >> in thinking that stress on a static structure absorbs energy or > >> momentum continuously over time. If the sail does not move > >> relative to the ship, then it cannot absorb or dissipate momentum > >> separately from the ship. It cannot absorb momentum if it does > >> not move, because momentum means motion. ---- > > (??!) > Thats like the old argument that if a tractor is pushing against a wall its > doing no work, since the wall isn't accelerated. The sail is getting a > thrust that is perpendicular to the surface of reflection. If you want to > describe the portion of the thrust that isn't accelerating the ship as > invalid, enjoy. S >> The tractor is dissipating energy because it contains S >> moving parts in its engine and drive train that keep S >> moving even though the tractor chassis and the wall S >> are not. Now whos trying to talk their way out of a corner. Try a direct drive electric tractor. Nothing turns unless the vehical moves. So where does the power go if nothing moves? -- S >> Lean a board against the wall. Does it dissipate energy S >> because it can't move the wall? Lean a heavy iron bar S >> against the wall. Does it dissipate more energy than S >> the board? They are under a constant 1 g thrust. They are under the load resisting that takes. Where do you think that power goes? S >> Are the bricks at the bottom of the wall permanently S >> warmer than the bricks at the top because they are under S >> compression? Yes. S >> --- You can't claim that gravity is continuously pumping S >> energy into the objects; you can't gain or lose energy if S >> you don't move up or down in a gravity field. If non-moving structures are not continuously being subjected to a force, what keeps them under continuous presure? Something is crushing their molecular structures enough to put them under a load. If that presure was removed, or droped, they would expand. In the same way the structure in the sail bracing is under continuous stress. S >> My intention was to prove that Kevin's parasail design S >> couldn't absorb photons without absorbing their S >> momentum. But you can divert the thrust vectors to a non-forward direction. in a reflection. Its not going to buy you anything is you later absorb the photons anyway, but it is a usefull trick to move the beam around without geting shoved by it. (Frankly with all the bouncing, have defined equations getting tossed around I'm not sure if that was Kevins point anymore.) s >> You seem to have a real misunderstanding of the s >> difference between work and potential. When you put a s >> structure under tension or compression, you do change s >> its energy, ONCE, when you slightly pull apart or scrunch s >> together Actually, I'm probably not being as clear as I might be. However, the differnce if fairly accademic as far as the ships concerned. > One very consistent problem in LIT over the last year has been > a very limited interest in the engineering realities of a > situation, and to much fondness for endless equation wars. s >> These are not equation wars; as this message shows, you s >> don't always have to use math to talk about physics. But in the Equation wars, no one was using anything but equations (usually not well explained or defined). This not only caused confusion to everyone else, it frequently tripped up the person making the statment Kelly From popserver Sun Dec 3 01:21:17 GMT 1995 X-VM-v5-Data: ([nil nil nil t t nil nil nil nil] ["412" "Sat" "2" "December" "1995" "20:07:48" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951202200747_42256550@emout04.mail.aol.com>" "17" "Re: one question" "^From:" nil nil "12" nil nil nil nil] nil) Received: from emout04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA15518; Sat, 2 Dec 95 17:05:38 PST Received: by emout04.mail.aol.com (8.6.12/8.6.12) id UAA13841; Sat, 2 Dec 1995 20:07:48 -0500 Message-Id: <951202200747_42256550@emout04.mail.aol.com> X-UIDL: 817953394.015 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: one question Date: Sat, 2 Dec 1995 20:07:48 -0500 >> > > Yes, in fact is does not take any energy to keep floating a few metres above >> > > Earth's surface. > >> >Well, it depends on how you make the object float. >> No, if you for example use a helicopter, it does not take energy to stay at >> that height but it does take energy to move all the air. >> Timothy Hold your arm out to you side. Tell me it takes no effort (energy) to hold it there. Kelly From popserver Sun Dec 3 01:21:18 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7156" "Sat" "2" "December" "1995" "20:08:04" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "171" "Re: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from emout04.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA15541; Sat, 2 Dec 95 17:06:18 PST Received: by emout04.mail.aol.com (8.6.12/8.6.12) id UAA13942; Sat, 2 Dec 1995 20:08:04 -0500 Message-Id: <951202200804_42256799@emout04.mail.aol.com> X-UIDL: 817953394.016 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Sat, 2 Dec 1995 20:08:04 -0500 >From : Timothy Subject : Prelaunching >>> This method of prelaunching fuel packets will cost the >>> same amount of energy that is needed if you take those >>> same packets with you from the start. > >True, but since the ship doesn't have to supply the energy, it saves an >incredable amount of fuel. TV > The ship does not have to supply the energy! It will leave TV > fully fueled. It is still accelerated by some kind of TV > photon beam. No, Kevins starship design is propelled by a photon (maser) beam. My origional Explorer design is propelled by fusion powered mass drivers. I call it an externally feed system since the fuel is thrown out ahead of the ship by a launcher in Sol. (See my Explorer starship design page on the LIT site.) Thats probably the central thing confusing you. Unless your confusing the Explorer ship with the plasma mirror design I came up with more recently. >To put it bluntly no fusion powered ship could >carry enough fuel, to accelerate itself and its fuel up to high reletivistic >speeds. Estimates are that a ship would need a 1,000,000 to 1 fuel to ship >mass ratio to get up to 10% of light speed. But if the ship doesn't have to >carry its fuel, a 200 to 1 ratio could get you most of the way to light speed >(or was that 1/3rd light speed. Been a while since GES ran the numbers off >for me.) TV > Huh, if it doesn't carry its fuel, how do you calculate a ratio? Figure out how much fuel it would take to run the reactors & engines enough to accelerate the ship (but not its fuel) up to speed. TV > !! Please be specific if you mean FUEL or REACTION MASS !! I was being specific. I ment fuel. (Thou I suppose you could save some bucks by adding in extra reaction mass to the launched shipments.) >>> The problem is that there are no accurate numbers of >>> the density of interstellar debris. So any number is almost >>> a guess. > >Thats been a constand problem for us. How do you design a ship to travel >through something you know next to nothing about? TV > It would be best if we could find a solution without using the interstellar TV > particles, but at the same time we should keep in mind TV > that we have to protect us against it. This may sound a TV > bit contradictory but a general solution would be best. How about working out a high and low range based on the most and least mass expected out there? =========================================================================== ReplyTo : Kelly >From : Timothy Subject : Plasma mirror >>> Replenishing the "mirror" will probably take lots of ions >>> or in other words mass that has to be taken with us. > >Agreed, but I don't have a handel on the amount of mass. TV > Why doesn't it have to do with the amount of mass? Don't understand you question. I was assuming it would depend on the mass, but I didn't know how much mass that would be. TV > Ions are particles too. They may have small masses, TV > but if you have enough of them you could build a TV > complete dragon-fly sail. I don't know which system would be lighter, but of course we couldn't build the dragon-fly system, so thats kind of a mute point. >>> Also using such a light (non heavy) sail will mean that >>> the "mirror" is accelerated a lot and lot of energy is lost >>> due to the Doppler effect. > >Given that the mirror is the surface of a plasma, and said plasma is being >continuously being replenished. I'm not sure the reflective "surface" is >actually moving? Althou obviously the particals in the plasma are moving >(and accelerating) rapidly. Are the micro waves reflecting off the >particals? Or off the area where the plasma is ionized enough to reflect >them? TV > Probably all the way in between. But that is not important TV > here, because a reflection means transfer of momentum, TV > and with it energy. Since the plasma will be accelerated TV > a lot, it will retrieve a lot of energy. Do you mean absorb a lot of energy? That is a problem with a drop mirrow or plasma mirror idea. But as long as you can do it and get thrust to decelerate the ship (the big problem in al this), it might work well enough to get us somewhere. (Assuming the whole thing doesn't melt the ship!) >>> Also I have doubts how well the "mirror" reflects, ionized >>> particles attract or repell each other so, it won't take long >>> befor the "mirror" has destroyed itself. > >The ions in a plasma of the same material wil repell each other. You might >be able to do some magnetic tricks to hold it, but it probably wouldn't be >worth the trouble. > >[ Hum --- I wounder if you could wiggle the exausting plasma to for a laser >to get back some of the energy? ] TV > Don't talk about plasma as if it where some easy to TV > control stuff. The movement of the plasma itself would TV > create magnetic fields. It's like boiling water but much TV > worse. I didn't say it was going to be easy. (Thou compared with the sail, the power generator, and transmitters; It will be a snap!) I just said it might be worth doing. I mean the plasma will have a LOT of energy in it. It might be worth tapping some off. >As to reflectivity. That would depend on the nature of the plasma and a lot >of other variables. This is probably not a question we could easily figure >out for ourselves. >>> Shock wave? I don't understand, please explain again. > >You have a mass of plasma being hit with E18 of energy. It will be HOT, and >highly ionized. It will be explosivly expanding. The light pressure of the >beam (or the feed mass) will probably keep it from flowing straight up the >beam. But it will be moving rapidly to the sides and forward or the ship. > We should be able to tap this for thrust. TV > My guess is that this shock wave will move mostly TV > forward instead of backward. If by forward, you mean toward Tau C. I agree. But like you said, plasmas get messy. One this hot will be blasting outward violently! We might be able to use the lateral plasma stream to push the ship beamwards. (Every little bit helps.) TV > You seem to want to do the same thing Kevin did: Make a TV > easy thing complicated and so loose complete control TV > over what you are doing. Whatever method you can think TV > of, it will take just as much energy that the TV > dragon-fly-sail will use. On the contrary. I'm trying to take a very complicated system and make it simpler. Notice I don't have the massive microwave to electric power converters of Kevin's origional drive system. Nor do I have the ultra exotic A.I. controled active structure of Forwards drop reflector sail. Forwards design would have had to steer itself, while steering the reflected beam back to the main ship, while tracking the main ship over interstellar distences. This is not easy, and it is REALLY pushing the envelope of probable 2050 technologies! On the other hand my plasma mirror idea would all take place in the area of the ship, and be directly controlable by the ship. Assuming it wasn't mass or energy prohibative, it would clearly be the prefered system. (Assuming it would work of course.) Kelly From popserver Sun Dec 3 02:57:05 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9996" "Sat" "2" "December" "1995" "18:56:38" "-0800" "Steve VanDevender" "stevev@efn.org" nil "211" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA19543; Sat, 2 Dec 95 18:52:32 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id SAA02132; Sat, 2 Dec 1995 18:56:38 -0800 Message-Id: <199512030256.SAA02132@tzadkiel.efn.org> In-Reply-To: <951202200736_42256412@emout05.mail.aol.com> References: <951202200736_42256412@emout05.mail.aol.com> X-UIDL: 817959168.000 From: Steve VanDevender To: KellySt@aol.com Cc: stevev@efn.org, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Sat, 2 Dec 1995 18:56:38 -0800 KellySt@aol.com writes: > to: stevev@efn.org > > > If a static structure had to dissipate energy continuously to > > > remain standing, where would such energy come from? Why doesn't > > > your house fall down? Where are the batteries? > > > > The energy is coming from the gravitational attraction of > > the earth. It is disapated as heat in the structure of the > > house. In a structure under heavy loads (too heavy) you > > can feel the heat in the structure. > > Steve>> Really? So when does the earth run out of gravity? > > When space gets tired of curving? ;) So what you are saying is that any gravitational source is a supply of infinite energy. All one need do is hang a weight from a wire or stack up a bunch of bricks, attach a thermocouple to the now warmer structure, and get free electricity, forever. This is such an amazingly simple principle that I am surprised such a method pf power generation has not been tapped already. Who needs sunlight to evaporate water to fall as rain to flow through rivers to run hydroelectric generators, when one could use a farm of gravitationally stretched or compressed objects and a heat exchanger to run a boiler to make steam to run the generators instead? The curvature of space also carries energy, but a finite amount. Objects in a gravitational field can't dissipate heat forever; the energy has to come from somewhere, and there is no such thing as an infinite inexhaustible supply of energy in the universe. > Steve>> I think you've spent too much time in the Cartoon > Steve>> Physics section of Acme Physics Warehouse. > > Steve>> Tell me about one of these structures that I can go > Steve>> visit, put my hand on, and feel the heat. > > Over stressed cable stayed structures are about the only ones I've delt with > that I could feel the differnce in. Others are too low to feel, but > insterments can detect it. Are these structures under true static stress? Is the heat coming from an overstressed, gradually elongating cable (in which case work is being done on the cable material), or can you set up such a structure and get heat from it forever without degeneration of the structure? If so, how do you explain getting more heat from the structure than you put energy into it when you built it? If such a structure could persist indefinitely, how do you explain where the energy came from when the structure has been around long enough that the total dissipated energy exceeds the energy equivalent of the mass of the structure and the gravitational source? > KellySt@aol.com writes: > > >> Besides not treating momentum as a vector quantity, people are > > >> making the mistake of thinking that lateral loading of the sail > > >> assembly is a magical sink for momentum or energy. The error is > > >> in thinking that stress on a static structure absorbs energy or > > >> momentum continuously over time. If the sail does not move > > >> relative to the ship, then it cannot absorb or dissipate momentum > > >> separately from the ship. It cannot absorb momentum if it does > > >> not move, because momentum means motion. ---- > > > > (??!) > > Thats like the old argument that if a tractor is pushing against a wall > its > > doing no work, since the wall isn't accelerated. The sail is getting a > > thrust that is perpendicular to the surface of reflection. If you want to > > describe the portion of the thrust that isn't accelerating the ship as > > invalid, enjoy. > > S >> The tractor is dissipating energy because it contains > S >> moving parts in its engine and drive train that keep > S >> moving even though the tractor chassis and the wall > S >> are not. > > Now whos trying to talk their way out of a corner. Try a > direct drive electric tractor. Nothing turns unless the > vehical moves. So where does the power go if nothing moves? If an electric motor is prevented from turning then the energy that is not producing motion heats the motor windings; if the motor does not turn then the windings are an electrical short circuit. An ideal electric motor draws no power if it does no work. As you should know as a student of engineering, ideal motors are as common as unbending beams. Any real motor has resistive and mechanical losses that will cause it to draw power even if it does no work. I can keep this up for a long time, because I know what I'm talking about. You are making claims that would get you a lot of stern looks from your physics professor, if not outright laughter. > S >> Lean a board against the wall. Does it dissipate energy > S >> because it can't move the wall? Lean a heavy iron bar > S >> against the wall. Does it dissipate more energy than > S >> the board? > > They are under a constant 1 g thrust. They are under the load > resisting that takes. Where do you think that power goes? There is no power dissipation, because there is no motion. Power isn't going anywhere. Power is work over time. Work is force times distance. A force that is prevented from producing motion produces no work; no work over any amount of time is no power. You have equated work (or energy) with force, a mistake that should have been corrected in your first class that covered Newtonian physics. > S >> Are the bricks at the bottom of the wall permanently > S >> warmer than the bricks at the top because they are under > S >> compression? > > Yes. You need to have a long, long talk with a physics professor. > S >> --- You can't claim that gravity is continuously pumping > S >> energy into the objects; you can't gain or lose energy if > S >> you don't move up or down in a gravity field. > > If non-moving structures are not continuously being subjected to a force, > what keeps them under continuous presure? Something is crushing their > molecular structures enough to put them under a load. If that presure was > removed, or droped, they would expand. In the same way the structure in the > sail bracing is under continuous stress. That stress requires extension in space. It is true that moving up and down in a gravity field changes the energy of the object. But if no motion occurs, there is no change in energy. The compression of the structure occurred once and added a finite amount of energy to it. There is no continuous dissipation of energy as you seem to think; the bricks at the bottom of the wall got warmer just after the other bricks were stacked on top of them, but do not stay warmer forever, because no more work is done on them. No motion through the gravity field means no work; no work is no energy. > S >> My intention was to prove that Kevin's parasail design > S >> couldn't absorb photons without absorbing their > S >> momentum. > > But you can divert the thrust vectors to a non-forward direction. in a > reflection. Its not going to buy you anything is you later absorb the > photons anyway, but it is a usefull trick to move the beam around without > geting shoved by it. (Frankly with all the bouncing, have defined equations > getting tossed around I'm not sure if that was Kevins point anymore.) You can reflect different parts of the beam in different directions to produce sideways components of momentum that cancel over the entire structure. You cannot take forward momentum and turn it into sideways momentum without giving the forward momentum completely to something else. When I say that momentum is a vector quantity and is conserved as a vector quantity, what I mean is that if you have a quantity of momentum, its direction is as important as its magnitude, and although you can divide the momentum up however you like, even split zero components into complementary non-zero components aimed in opposite directions, the sum of all the momenta of all the things you divide it up among sums to momentum in the same direction with the same magnitude. The ship gets all of the forward momentum of each photon it absorbs, no matter how the photon was reflected or redirected before the ship finally absorbed it. There is no other way to satisfy conservation of momentum. > s >> You seem to have a real misunderstanding of the > s >> difference between work and potential. When you put a > s >> structure under tension or compression, you do change > s >> its energy, ONCE, when you slightly pull apart or scrunch > s >> together > > Actually, I'm probably not being as clear as I might be. However, the > differnce if fairly accademic as far as the ships concerned. Frankly, your understanding of physics would get you marked as a raving loon. > > One very consistent problem in LIT over the last year has been > > a very limited interest in the engineering realities of a > > situation, and to much fondness for endless equation wars. > > s >> These are not equation wars; as this message shows, you > s >> don't always have to use math to talk about physics. > > But in the Equation wars, no one was using anything but equations (usually > not well explained or defined). This not only caused confusion to everyone > else, it frequently tripped up the person making the statment How much math have I used to explain conservation of energy and momentum here? I think I have a clear and accurate understanding of those concepts, which does not lead me to the contradictory conclusions you are coming up with. Your claims quite clearly imply that you can get indefinite amounts of heat energy from an unmoving structure in a gravitational field, because you say a structure in a gravitational field is warmer and stays warmer than an equivalent structure not in a gravitational field. You cannot claim to be playing by the same rules of physics that the rest of us are trying to play by. Your knowledge of physics has flaws and gaps that I have already spent too much time trying to correct and fill. From popserver Sun Dec 3 04:16:42 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1686" "Sat" "2" "December" "1995" "19:19:08" "-0800" "Steve VanDevender" "stevev@efn.org" nil "41" "Re: one question" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA20322; Sat, 2 Dec 95 19:14:58 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id TAA02187; Sat, 2 Dec 1995 19:19:08 -0800 Message-Id: <199512030319.TAA02187@tzadkiel.efn.org> In-Reply-To: <951202200747_42256550@emout04.mail.aol.com> References: <951202200747_42256550@emout04.mail.aol.com> X-UIDL: 817963945.000 From: Steve VanDevender To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: one question Date: Sat, 2 Dec 1995 19:19:08 -0800 KellySt@aol.com writes: > >> > > Yes, in fact is does not take any energy to keep > >> > > floating a few metres above Earth's surface. > > > >> >Well, it depends on how you make the object float. > > >> No, if you for example use a helicopter, it does not take > >> energy to stay at that height but it does take energy to > >> move all the air. > > >> Timothy > > Hold your arm out to you side. Tell me it takes no effort (energy) to hold > it there. Your muscles are not static structures, as I have pointed out before. They produce force with protein fibers that must continually dissipate energy by moving molecules around to maintain constant tension. This constant chemical activity is what you feel as effort when you hold out your arm. Now nail a board at a right angle to a vertical post. How much energy does it take to hold it there? None. How much energy did it take to put it there? Some to lift the board and pound the nails. The motions required to do those actions performed work; they involved application of force over a distance. Some of this work heated the nails and the board; once you are done pounding no more energy is put into the nails or the board, and they cool. Once they cool to ambient temperature no more energy goes into or out of the board and the nails. Gravity cannot change the energy of the board because the board does not move through the gravitational field. That it takes effort for your body to produce a constant force does not mean that all forces result from constant effort (dissipation of energy). It means that your body is not an ideal machine. A force that produces no motion dissipates no energy. From popserver Sun Dec 3 10:37:08 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4895" "Sun" "3" "December" "1995" "00:22:14" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "114" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "12" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA26674; Sat, 2 Dec 95 22:19:47 PST Received: by maroon.tc.umn.edu; Sun, 3 Dec 95 00:22:15 -0600 In-Reply-To: <199512030256.SAA02132@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 817986764.003 From: Kevin C Houston To: Steve VanDevender Cc: KellySt@aol.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Sun, 3 Dec 1995 00:22:14 -0600 (CST) On Sat, 2 Dec 1995, Steve VanDevender wrote: > > S >> My intention was to prove that Kevin's parasail design > > S >> couldn't absorb photons without absorbing their > > S >> momentum. i now accept this point as proven. > You can reflect different parts of the beam in different > directions to produce sideways components of momentum that cancel > over the entire structure. You cannot take forward momentum and > turn it into sideways momentum without giving the forward > momentum completely to something else. When I say that momentum Okay, let's think about that for a moment. Is it possible to absorb the photons into the Reaction Mass (RM), giving all of the energy _and_ momentum to the exhaust stream. since the exhaust stream consists of (ideally) the recieved photons and extra mass, would this slow the system. Half formed idea follows: (modifications/analysis welcomed) __________ |RM inlet ship's core /"/ Power from Sol ______________/"/________ ~~~~~~~~~~~~~~~~~~~~~~============"="="="="="="="="="" exhaust and power ~~~~~~~~~~~~~~~~~~~~~~============="="="="="="="="="=" ~~~~~~~~~~~~~~~~~~~~~~============"="="="="="="="="="" ______________ _________ \"\ \"\ |RM inlet ~ Photons going one way = photons going both directions (canceling? hope not) " Reaction Mass Of course this assumes we can aim a maser straight up the butt of the ship over light years, which of course we cant. But, numerous reflections could collect the energy over square kilometers, and focus it in the required manner, producing the same net result. If your objection is to this paragraph, then hold your horses, because I'm dubious about this part myself. remember, I just thought this up about 20 miuntes ago (as I'm writing this) so there may be a few bugs my question is this: does the ship slow down? I think it should. (but I've been wrong before) before the interaction, the ship and the RM were traveling to the right with some speed V. after the interaction, the RM is traveling at a greatly increased speed to the right, and the photon beam is traveling to the left. (complete reflection -- don't ask me how, just assume it for the moment.) Now absorb the photon beam and convert it to electricity. (the ship should act as though the photons came from Tau Ceti, slowing even more.) -- again, we either need a magical one-way absorber at the ~/= interface (~ photons enter from the left, = photons are absorbed from the right), or a complicated series of reflectors. or we have to abandon the photons capture and just let all that lovely energy zing back to earth. the electricity (if we can capture it) can then be used to power a lineac, acellerating the plasma stream even more. which definitly would slow the ship I think this is what Kelly was trying to get at with his plasma mirror, but this puts the mirror inside the ship. I realize that I'm talking about some very very complicated twists and turns, but just answer the following question. is this system physically possible? does it preserve momenergy, and does the ship slow down. we can worry about the merely difficult engineering tasks later. > is a vector quantity and is conserved as a vector quantity, what > I mean is that if you have a quantity of momentum, its direction > is as important as its magnitude, and although you can divide the > momentum up however you like, even split zero components into > complementary non-zero components aimed in opposite directions, > the sum of all the momenta of all the things you divide it up > among sums to momentum in the same direction with the same > magnitude. > here's how I see it breaking down, 1 photons reflecting off RM: Momenergy (very dangerous of me to toss a word around that I don't fully understand.) conserved by acceleration of RM. Ship slows down a little or not at all (photons momentum equals RM momentum and ship stays the same??? but ship now has less mass ) 2 reflected photons absorbed: Momenergy conserved by ship slowing down. 3 electricity used to further accelerate RM. ship slows down even more. I cannot begin to solve the math showing how much the ship slows down, or how much energy is required, or how much RM is required. I'm not even sure the physical model is correct. help. Kevin PS, I do appreciate your kind tutuledge Steve, I know it must be frustrating trying to pound knowledge into a head as thick as mine, especially through such a small bandwidth channel like this. From popserver Sun Dec 3 23:14:51 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5158" "Sun" "3" "December" "1995" "22:24:12" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "120" "Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA21840; Sun, 3 Dec 95 13:21:05 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA26247 (5.67b/IDA-1.5 for ); Sun, 3 Dec 1995 22:24:03 +0100 Message-Id: <199512032124.AA26247@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818032205.019 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sun, 03 Dec 1995 22:24:12 +0100 ReplyFrom : Timothy ReplyTo : Kelly Subject : Humans and stairs >Hold your arm out to you side. Tell me it takes no effort (energy) to hold >it there. Even if I could convince you that it took no energy to keep it there, you would probably say that the only possibility was that my feet got colder. But serious, it is not that easy to explain this easy in an other way than Steve and I did earlier. So let me ask you a question: Does it TAKE energy to walk down the stairs or does it GIVE energy? If it takes energy, would that not mean that walking up the stairs would give energy? And if it gives energy, why use people elevators or lifts? I'm not trying to make fun out of you, but I'm trying to point you at the errors in your theory. Since you probably are better at looking in yourself than I am, my hopes are that with these questions you solve the difficulties yourself. problems. Timothy =========================================================================== ReplyFrom : Timothy ReplyTo : Kelly Subject : Prelaunching >No, Kevins starship design is propelled by a photon (maser) beam. My >origional Explorer design is propelled by fusion powered mass drivers. I >call it an externally feed system since the fuel is thrown out ahead of the >ship by a launcher in Sol. (See my Explorer starship design page on the LIT >site.) Thats probably the central thing confusing you. Unless your >confusing the Explorer ship with the plasma mirror design I came up with more >recently. Ah, now I see. But you agreed that both prelaunching and taking-all-with-us takes the same amount of energy/fuel. But after understanding it, I think that that prelaunching is more economic with energy. >Figure out how much fuel it would take to run the reactors & engines enough >to accelerate the ship (but not its fuel) up to speed. I've started a calculation, but as far as I can see it now, this method is not much more efficient than the take-it-all-with-us method. Furthermore, prelaunching only works for acceleration, not for decelleration. >> It would be best if we could find a solution without using the interstellar >> particles, but at the same time we should keep in mind >> that we have to protect us against it. This may sound a >> bit contradictory but a general solution would be best. > >How about working out a high and low range based on the most and least mass >expected out there? That would be fine with me, but I have a feeling that using the ISM to break will not work. But OK, does anyone have the number of particles per cubic metre? =========================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >Don't understand you question. I was assuming it would depend on the mass, >but I didn't know how much mass that would be. I guess, I was having difficulties with the expression "I don't have a handle". >> Ions are particles too. They may have small masses, >> but if you have enough of them you could build a >> complete dragon-fly sail. > >I don't know which system would be lighter, but of course we couldn't build >the dragon-fly system, so thats kind of a mute point. We can't build a dragon-fly system? I don't agree with that. Just make a big (heavy) mirror and detach just before the Asimov is going to decelerate and the mirror is going to accelerate. >> Probably all the way in between. But that is not important >> here, because a reflection means transfer of momentum, >> and with it energy. Since the plasma will be accelerated >> a lot, it will retrieve a lot of energy. > >Do you mean absorb a lot of energy? That is a problem with a drop mirrow or >plasma mirror idea. But as long as you can do it and get thrust to >decelerate the ship (the big problem in al this), it might work well enough >to get us somewhere. (Assuming the whole thing doesn't melt the ship!) No, I meant retrieving energy in the form of kinetic energy: The plasma is accelerated much as the photons are reflected on it. >On the contrary. I'm trying to take a very complicated system and make it >simpler. Notice I don't have the massive microwave to electric power >converters of Kevin's origional drive system. Nor do I have the ultra exotic >A.I. controled active structure of Forwards drop reflector sail. Forwards >design would have had to steer itself, while steering the reflected beam back >to the main ship, while tracking the main ship over interstellar distences. > This is not easy, and it is REALLY pushing the envelope of probable 2050 >technologies! Are you sure that you know how the Dragon-fly or retro-reflection method works? Because I don't see why a plasma mirror is easier than a solid mirror. >On the other hand my plasma mirror idea would all take place in the area of >the ship, and be directly controlable by the ship. Assuming it wasn't mass >or energy prohibative, it would clearly be the prefered system. (Assuming it >would work of course.) Indeed, if it wasn't for the mass or energy it would certainly have a pre. But I'm quite certain that especially the mass would be the problem. From popserver Sun Dec 3 23:15:05 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1224" "Sun" "3" "December" "1995" "23:48:23" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "31" "Engineering newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA25328; Sun, 3 Dec 95 14:45:03 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA00758 (5.67b/IDA-1.5 for ); Sun, 3 Dec 1995 23:48:16 +0100 Message-Id: <199512032248.AA00758@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818032205.027 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering newsletter Date: Sun, 03 Dec 1995 23:48:23 +0100 ReplyTo : Kevin ReplyFrom : Timothy Subject : Dragonfly? >I think this is what Kelly was trying to get at with his plasma mirror, >but this puts the mirror inside the ship. I realize that I'm talking >about some very very complicated twists and turns, but just answer the >following question. is this system physically possible? does it >preserve momenergy, and does the ship slow down. we can worry about the >merely difficult engineering tasks later. Yes, it looks much like it, and I have the same comment, why not use a simple massive mirror that works according to the dragon-fly principle. >here's how I see it breaking down, > >1 photons reflecting off RM: > >Momenergy (very dangerous of me to toss a word around that I don't fully >understand.) conserved by acceleration of RM. Ship slows down a little or >not at all (photons momentum equals RM momentum and ship stays the >same??? but ship now has less mass ) > >2 reflected photons absorbed: >Momenergy conserved by ship slowing down. > >3 electricity used to further accelerate RM. ship slows down even more. It would be better not to absorb the photons, but reflect them right away. Steve showed that a long time ago. From popserver Sun Dec 3 23:14:59 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["688" "Sun" "3" "December" "1995" "14:30:47" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "14" "Re: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from wolfe.net (mail1.wolfe.net) by efn.efn.org (4.1/smail2.5/05-07-92) id AA24281; Sun, 3 Dec 95 14:22:26 PST Received: from sea-ts2-p48.wolfenet.com (sea-ts2-p48.wolfenet.com [204.157.98.166]) by wolfe.net (8.7/8.7) with SMTP id OAA20330; Sun, 3 Dec 1995 14:30:47 -0800 (PST) Message-Id: <199512032230.OAA20330@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818032205.023 From: rddesign@wolfenet.com To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sun, 3 Dec 1995 14:30:47 -0800 (PST) >We can't build a dragon-fly system? I don't agree with that. Just make a big >(heavy) mirror and detach just before the Asimov is going to decelerate and >the mirror is going to accelerate. Lookout, here comes the novice again. :-) If yoyu are thinking about dicarding the mirror or anything else, think about dumping it as Reaction Mass into the drive and use it to help slow this puppy down. Along with mass brought along just for this purpose a dent could be made in slowing the ship. Deploy a second "sail/mirror" behind the ship to feed solar energy from TC into the drive to assist also. think about simpler soultions. The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Mon Dec 4 06:55:54 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["4219" "Mon" "4" "December" "1995" "00:29:18" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<951204002917_124214983@mail02.mail.aol.com>" "112" "Re: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from mail02.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA11586; Sun, 3 Dec 95 21:26:54 PST Received: by mail02.mail.aol.com (8.6.12/8.6.12) id AAA20779; Mon, 4 Dec 1995 00:29:18 -0500 Message-Id: <951204002917_124214983@mail02.mail.aol.com> X-UIDL: 818059876.006 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Mon, 4 Dec 1995 00:29:18 -0500 Subj: Engineering Newsletter Date: Sun, Dec 3, 1995 4:24 PM EST From: T.L.G.vanderLinden@student.utwente.nl X-From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl ReplyFrom : Timothy ReplyTo : Kelly Subject : Humans and stairs >Hold your arm out to you side. Tell me it takes no effort (energy) to hold >it there. >> Even if I could convince you that it took no energy to keep >> it there, you would probably say that the only possibility >> was that my feet got colder. Don't bother. I refused to get into an argument over levitating arms. >> Does it TAKE energy to walk down the stairs or does it GIVE energy? Actually both take energy since your accelerating and decelerating masses of your body. Though obviously going down you don't need to bost yourself up a gravity/potential energy well. =========================================================================== ReplyFrom : Timothy ReplyTo : Kelly Subject : Prelaunching >No, Kevins starship design is propelled by a photon (maser) beam. My >origional Explorer design is propelled by fusion powered mass drivers. I >call it an externally feed system since the fuel is thrown out ahead of the >ship by a launcher in Sol. (See my Explorer starship design page on the LIT >site.) Thats probably the central thing confusing you. Unless your >confusing the Explorer ship with the plasma mirror design I came up with more >recently. >> Ah, now I see. But you agreed that both prelaunching and taking-all-with-us >> takes the same amount of energy/fuel. But after understanding it, I think >> that that prelaunching is more economic with energy. Energy total yes. Energy on the ship, no. Since the ship power requierments are the show stoper of the system.. >> Furthermore, prelaunching only works for acceleration, not for decelleration. Agreed, but then you can say the same thing about photon sailers. >> It would be best if we could find a solution without using the interstellar >> particles, but at the same time we should keep in mind >> that we have to protect us against it. This may sound a >> bit contradictory but a general solution would be best. > >How about working out a high and low range based on the most and least mass >expected out there? >> >That would be fine with me, but I have a feeling that using the ISM to break >> >will not work. But OK, does anyone have the number of particles per cubic metre? I listed some assumptions on my Explorer Web page in LIT. I think bottom assumption was a hydrogen atom every cubic centameter or 4. =========================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >Don't understand you question. I was assuming it would depend on the mass, >but I didn't know how much mass that would be. >> I guess, I was having difficulties with the expression "I don't have a handle". Sorry for the slang. English to englist translation. I don't know what the answer is. >> Ions are particles too. They may have small masses, >> but if you have enough of them you could build a >> complete dragon-fly sail. > >I don't know which system would be lighter, but of course we couldn't build >the dragon-fly system, so thats kind of a mute point. >> >>We can't build a dragon-fly system? I don't agree with that. Just make a big >> >>(heavy) mirror and detach just before the Asimov is going to decelerate and >> >>the mirror is going to accelerate. Sorry that won't work. As the outer mirror moves away from the ship it has to continuosly reshape itself to refocus on the smaller catcher mirror/sail on the ship. Also without the anchor on the ship it will tend to flutter and shift off course due to slight variations in beam, ISM, mirror reflectvity, seperation torque, etc.. This of course ignores the fact the sail isn't rigid, and will tend to crumple once its free of the ship. Forward realized this, thats why he had an army of autonomus robots go with the outer sail to keep it working. Kelly From popserver Mon Dec 4 07:16:09 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2828" "Sun" "3" "December" "1995" "23:14:09" "-0800" "Steve VanDevender" "stevev@efn.org" nil "60" "Re: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA15476; Sun, 3 Dec 95 23:09:53 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id XAA11724; Sun, 3 Dec 1995 23:14:09 -0800 Message-Id: <199512040714.XAA11724@tzadkiel.efn.org> In-Reply-To: <199512032230.OAA20330@wolfe.net> References: <199512032230.OAA20330@wolfe.net> X-UIDL: 818061104.000 From: Steve VanDevender To: rddesign@wolfenet.com Cc: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden), KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sun, 3 Dec 1995 23:14:09 -0800 rddesign@wolfenet.com writes: > >We can't build a dragon-fly system? I don't agree with that. Just make a big > >(heavy) mirror and detach just before the Asimov is going to decelerate and > >the mirror is going to accelerate. > > Lookout, here comes the novice again. :-) > If yoyu are thinking about dicarding the mirror or anything else, think > about dumping it as Reaction Mass into the drive and use it to help slow > this puppy down. Along with mass brought along just for this purpose a dent > could be made in slowing the ship. Deploy a second "sail/mirror" behind the > ship to feed solar energy from TC into the drive to assist also. > think about simpler soultions. > The best Beads come from RD Designs. > Ric & Denisse Hedman To quickly summarize an earlier discussion: The novel _Flight of the Dragonfly_ by physicist Robert L. Forward describes a starship, called the Dragonfly, which uses a unique lightsail design. During the boost phase of the trip, the ship uses a single large lightsail to accelerate, powered by lasers from the Solar system. At the end of the boost phase, the large sail is detached but left intact. A smaller forward-facing sail is deployed on the ship. During the deceleration phase, the lasers remain aimed towards the large sail (with ship ship and small sail shadowing part of it), which is designed to carefully focus the incident light back towards the small sail. With this design, an ship can be accelerated and decelerated with lightsails powered from the system of origin. It's also pretty clean in terms of its physical behavior, although the task of focusing light from the forward sail to the retro sail is not trivial as the distances involved are very large. It is likely to be more efficient than using the sail material as reaction mass since it uses photons (already demonstrated to be a better form of "reaction mass" than any other material) exclusively for transferring momentum. The design still has some difficulties, the biggest of which is the focusing problem. Heavy use of such spacecraft would leave drifting relativistic-speed light sails zooming around the universe. These would gradually disintegrate from interactions with interstellar gas, if of course they didn't disintegrate while in use. The power coming from the forward sail gets pretty red-shifted near the end of the trip when the ship is nearly stopped; like most relativistic light-sail designs you have to turn up the power over the course of the trip. In some ways I think the Dragonfly sail (if I was sure that Forward invented it, I would call it the Forward sail both in his honor and for the mnemonic appropriateness) is a much cleaner and possibly more effective design than any of the other externally-powered ship designs that have been considered so far. From popserver Mon Dec 4 09:37:15 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2224" "Mon" "4" "December" "1995" "01:35:33" "-0800" "Steve VanDevender" "stevev@efn.org" nil "49" "Re: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA20152; Mon, 4 Dec 95 01:31:15 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id BAA12035; Mon, 4 Dec 1995 01:35:33 -0800 Message-Id: <199512040935.BAA12035@tzadkiel.efn.org> In-Reply-To: <951204002917_124214983@mail02.mail.aol.com> References: <951204002917_124214983@mail02.mail.aol.com> X-UIDL: 818069569.000 From: Steve VanDevender To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Mon, 4 Dec 1995 01:35:33 -0800 KellySt@aol.com writes: > ReplyFrom : Timothy > ReplyTo : Kelly > Subject : Humans and stairs > > >Hold your arm out to you side. Tell me it takes no effort (energy) to hold > >it there. > > >> Even if I could convince you that it took no energy to keep > >> it there, you would probably say that the only possibility > >> was that my feet got colder. > > Don't bother. I refused to get into an argument over levitating arms. > > >> Does it TAKE energy to walk down the stairs or does it GIVE energy? > > Actually both take energy since your accelerating and decelerating masses of > your body. Though obviously going down you don't need to bost yourself up a > gravity/potential energy well. Tell me this, Kelly. Given a rod of mass m and height h, standing vertically in a uniform gravitational field that produces acceleration g, what is the power in watts of heat energy dissipated by the rod? I'll also accept a formula that gives the dissipation of an infinitesimal element at the bottom of the rod; it would be sufficient for determining the power dissipated by any section of the rod by integrating the formula over that section. Pointers to experiments that have been done to demonstrate this effect would also be helpful in convincing me that it's real. I'm also curious about whether you'd draw a distinction between that rod standing in a gravity field and the same rod clamped horizontally in a vise -- in either case the rod is under compression forces, but the rod clamped in a vise is not getting its compression from the gravity field. Does the rod in the vise also dissipate heat for as long as it's under compression? Why or why not? If it does, where does the energy come from, and what is the relationship between the tension or compression and the heat dissipated by the rod? Like Timothy, I'm not doing this to make fun of you. You are stating an opinion that is at odds with accepted laws of physics, at least as we understand them. If your belief that standing structures dissipate heat because of tension or compression forces has any truth, then it should be possible to demonstrate the effect experimentally and produce a theory that explains the effect. From popserver Mon Dec 4 09:42:19 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8602" "Mon" "4" "December" "1995" "01:40:36" "-0800" "Steve VanDevender" "stevev@efn.org" nil "202" "Re: Summarry of the momentum wars and idea." "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA20238; Mon, 4 Dec 95 01:36:20 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id BAA12049; Mon, 4 Dec 1995 01:40:36 -0800 Message-Id: <199512040940.BAA12049@tzadkiel.efn.org> In-Reply-To: References: <199512030256.SAA02132@tzadkiel.efn.org> X-UIDL: 818069874.000 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Mon, 4 Dec 1995 01:40:36 -0800 Kevin C. Houston writes: > Half formed idea follows: (modifications/analysis welcomed) > > > __________ > |RM inlet > ship's core /"/ > Power from Sol ______________/"/________ > ~~~~~~~~~~~~~~~~~~~~~~============"="="="="="="="="="" exhaust and power > ~~~~~~~~~~~~~~~~~~~~~~============="="="="="="="="="=" > ~~~~~~~~~~~~~~~~~~~~~~============"="="="="="="="="="" > ______________ _________ > \"\ > \"\ > |RM inlet > > > ~ Photons going one way > = photons going both directions (canceling? hope not) > " Reaction Mass > > my question is this: > does the ship slow down? As drawn, I don't think so. The reason a rocket accelerates is that it reacts some material to produce pressurized gas in a vessel that is open on one end. The gas escapes from the opening, and the rocket moves in reaction because the pressure on the vessel (which is attached to the rocket) is asymmetric -- constant everywhere except at the opening. In microscopic terms all of the molecules that get forward momentum from the reaction bounce off the forward side of the vessel and transfer momentum to it. What you've built is sort of like a rocket that's a big open tube. Once the reaction mass is dumped into the tube, it's accelerated by the maser, but there's no way for it to transfer momentum with the ship. A chemical rocket built that way would just spew flame out each end of the pipe and not move. Here, whether the reaction mass absorbs or reflects the laser energy, it does so independently of the ship. A simple analogy might be to consider the difference between you throwing a baseball in zero-g and drifting backwards from the reaction, or placing a baseball in front of you and having someone shoot it with a rifle. The baseball goes flying away but you don't move from where you started. > I think it should. (but I've been wrong before) before the interaction, > the ship and the RM were traveling to the right with some speed V. after > the interaction, the RM is traveling at a greatly increased speed to the > right, and the photon beam is traveling to the left. (complete reflection > -- don't ask me how, just assume it for the moment.) I'll allow the hypothetical complete reflection, and your analysis of this part looks correct. The reaction mass accelerates but the ship doesn't slow down. > Now absorb the photon beam and convert it to electricity. > (the ship should act as though the photons came from Tau Ceti, slowing > even more.) -- again, we either need a magical one-way absorber at the > ~/= interface (~ photons enter from the left, = photons are absorbed from > the right), or a complicated series of reflectors. or we have to abandon > the photons capture and just let all that lovely energy zing back to earth. > > the electricity (if we can capture it) can then be used to power a lineac, > acellerating the plasma stream even more. which definitly would slow the ship > > I think this is what Kelly was trying to get at with his plasma mirror, > but this puts the mirror inside the ship. I realize that I'm talking > about some very very complicated twists and turns, but just answer the > following question. is this system physically possible? does it > preserve momenergy, and does the ship slow down. we can worry about the > merely difficult engineering tasks later. In principle this is really much like the Dragonfly two-piece lightsail. It's OK to reflect the photons backwards and use them to decelerate as long as you give the forward momentum from the original forward-moving photons to something, whether it's the Dragonfly forward sail or the reaction mass you're throwing into the pipe. > here's how I see it breaking down, > > 1 photons reflecting off RM: > > Momenergy (very dangerous of me to toss a word around that I don't fully > understand.) conserved by acceleration of RM. Ship slows down a little or > not at all (photons momentum equals RM momentum and ship stays the > same??? but ship now has less mass ) My thinking is that you are right that the ship won't slow down. Momenergy is Taylor and Wheeler's invented term. Their rationale for creating the concept seemed to be: 1. Conservation of energy is a major principle of physics. 2. Conservation of momentum is a major principle of physics. 3. Momentum and energy are conserved independently of each other, so energy can be added as a fourth component to a momentum vector, and normal vector operations will preserve conservation of the components. 4. When using total (rather than kinetic) energy for an object, there is a geometrically compelling interpretation for the resulting "momenergy" vector -- it points in the same direction as the velocity vector of the object, and its Lorentz magnitude is equal to the mass (in Timothy's terms, "rest mass") of the object. They then use momenergy vectors as fundamental items in relativistic kinematics problems. Conservation is handled automatically by requiring that the sum of momenergy vectors of all the components of an interaction remains the same before and after any interaction. In simple problems where you use one spatial dimension and momenergy vectors are two-dimensional, you can even draw nice diagrams on paper to show relationships, which is handy for solving problems. I write full four-dimensional momenergy vectors as: [ energy x-momentum y-momentum z-momentum ] The Lorentz magnitude of this vector is: sqrt(energy^2 - x-momentum^2 - y-momentum^2 - z-momentum^2) A more leisurely-paced explanation of momenergy vectors is in Chapter 7 of Taylor and Wheeler's _Spacetime Physics_. Have you bought your copy yet? > 2 reflected photons absorbed: > Momenergy conserved by ship slowing down. This is OK too, given your previous assumptions. > 3 electricity used to further accelerate RM. ship slows down even more. This is actually a very interesting idea. A small problem is that accelerating the reaction mass forward means that any light reflected back from it will be lower in energy because of doppler-shifting, so you get less energy back to accelerate further reaction mass. > I cannot begin to solve the math showing how much the ship slows down, or > how much energy is required, or how much RM is required. I'm not even > sure the physical model is correct. > > help. Well, I can at least show you how I'd start laying out the solution using the methods I'm familar with. First, let's pick a frame for doing the analysis. I tend to like using a frame where the spacecraft is initially at rest. So in this frame, the ship has momenergy [ s 0 ] (since motion in only one dimension is necessary for this analysis, I'll use 2-d vectors), and photons with momenergy [ p p ] are being beamed to the ship. This gives us the first major constraint on the solution -- no matter what happens, the total momenergy after any interaction will be [ s+p p ]. The intended reaction is to eject some quantity of reaction mass r into the photon beam, diminishing the ship's mass to s-r. This reaction mass also reflects the photons backward (in your ideal case), and the ship absorbs them. So now we have a system with these momenergies: ship: [ se sp ] reaction mass: [ re rp ] We also have the relationships: The invariant mass of the ship after ejecting the reaction mass is the magnitude of its momenergy vector: (s - r)^2 = magnitude [ se sp ] = se^2 - sp^2 Similarly, the invariant mass of the ejected reaction mass is the magnitude of its momenergy vector: r^2 = magnitude [ re rp ] = re^2 - rp^2 The momenergy vectors of the system components after the reaction is the same as the sum of the components before the reaction: [ se sp ] + [ re rp ] = [ s 0 ] + [ p p ] = [ s+p p ] It's too late for me to want to work on solving this now, but hopefully with appropriate juggling several of these variables can be eliminated and the final result can be expressed in terms of the quantities we consider known: s, r, p. > Kevin > > PS, I do appreciate your kind tutuledge Steve, I know it must be > frustrating trying to pound knowledge into a head as thick as mine, > especially through such a small bandwidth channel like this. If I keep this up I'd better get tenure in the LIT Physics department :-). From popserver Mon Dec 4 10:07:40 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["3641" "Mon" "4" "December" "1995" "03:59:52" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "80" "Retro sailing difficulties" "^From:" nil nil "12" nil nil nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA21089; Mon, 4 Dec 95 01:57:18 PST Received: by maroon.tc.umn.edu; Mon, 4 Dec 95 03:59:53 -0600 Reply-To: Kevin C Houston In-Reply-To: <199512040714.XAA11724@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII X-UIDL: 818071394.000 From: Kevin C Houston Sender: Kevin C Houston To: Steve VanDevender Cc: rddesign@wolfenet.com, Timothy van der Linden , KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Retro sailing difficulties Date: Mon, 4 Dec 1995 03:59:52 -0600 (CST) To: all I think another problem with a retro reflective sail is that it puts an effective upper limit on acceleration and speed of the ship. I'm not sure what that limit is, but it must be substantially below 1 G accel, and far below C at turnaround. The whole idea with an externally fueled (either mass or photonic) ship was to keep gravity constant and get close to C. But observe what happens near turnaround if you do this with a retro reflective mirror. At turnaround, the ship and mirror are moving at .99 of C. Ship and mirror are detached. outer sail begins to accelerate even more. the outer ring sail begins to get inefficient _twice_. Once, when it sees the maser from earth redshifted, and twice, when the ship sees the reflected beam redshifted _again_. At the limit, it begins to look like Steve's two mirror puzzle. We'd get almost nothing out of the mirror as it asymtotically approached the speed of light. The plasma mirror avoids these difficulties. Since the mirror is constantly being renewed at the ship's speed, the primary reflection gets more and more efficient as the ship slows down. Also, this allows us to use the plasma mirror as reaction mass at the same time we're using it for retro reflection. plasma exhaust may not be the most efficient in the universe, but it's the best I can find if you want to get near C. How to aim a maser up the butt of the ship from twelve light years away: Simple really, just reflect the maser off the main sail with the focus at one end of the core. a second mirror there re-reflects the maser up the central core. (Foreward shows in his design a way to make diseparate beams enter into a colimator, and emerge as one coherent beam.) How to support a large sail structure hanging off the ship. it supports itself, because it is a parabolic shape, the reflection off of the innermost part of the main sail imparts almost no perpendicular force component. the beam that reflects off the outermost part of the main sail imparts a larger perpendicular (to the ships direction of flight) component and thus keeps the sail "inflated". How to make the plasma go out one end only: a transparent (to whatever energy beam we use) plate on the back end would allow the energy in, but prevent the the plasma from escaping no furling or unfurling of the main sail is required, the whole thing can be controlled by the secondary mirror. if it is retracted, then the maser bounces off the main sail, imparting thrust to the ship. Without a second mirror to bounce off of, the ship accelerates away from Sol. To begin slow-down, (can't even call it turnaround anymore, things sure have changed.) the secondary mirror is extended to intercept the reflected beam and send it into the core. The beam hits a wall of plasma, bounces off, and hits an absorber. (it can't be bounced back, because then it would just hit the plasma again, and be going in the wrong direction -- back toward Sol) The absorbed energy is then used to power ship's systems and further accelerate the plasma. if anyone can figure out how to bounce the maser beam back toward TC after it hits the plasma, I'll gladly scrap the accelerating-the-plasma with-the-converted-energy idea. which would save us from having to use microwaves, and help out with our heat load. Kevin P.S. to Steve. I just got your analysis of the design as i was about to send this. seems reasonably well laid out. BTW, what is the ISBN of Taylor and Wheeler's book? that will help me to order it. It will be a week or so before i can do any detailed work on it. From popserver Mon Dec 4 21:29:05 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4216" "Mon" "4" "December" "1995" "12:27:43" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "90" "Re: Retro sailing difficulties" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA23250; Mon, 4 Dec 95 03:24:32 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA09586 (5.67b/IDA-1.5 for ); Mon, 4 Dec 1995 12:27:38 +0100 Message-Id: <199512041127.AA09586@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818112256.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Retro sailing difficulties Date: Mon, 04 Dec 1995 12:27:43 +0100 To: Kevin >I think another problem with a retro reflective sail is that it puts an >effective upper limit on acceleration and speed of the ship. I'm not >sure what that limit is, but it must be substantially below 1 G accel, >and far below C at turnaround. The whole idea with an externally fueled >(either mass or photonic) ship was to keep gravity constant and get close >to C. > >But observe what happens near turnaround if you do this with a retro >reflective mirror. > >At turnaround, the ship and mirror are moving at .99 of C. Ship and >mirror are detached. outer sail begins to accelerate even more. >the outer ring sail begins to get inefficient _twice_. Once, when it sees >the maser from earth redshifted, and twice, when the ship sees the >reflected beam redshifted _again_. I hadn't thought of that second shift... >At the limit, it begins to look like Steve's two mirror puzzle. We'd get >almost nothing out of the mirror as it asymtotically approached the speed >of light. But in the end it is also easier to decelerate: E=0.5 m v^2 The difference between v=1001 and v=1000 is dE=2001 while the difference between v=101 and v=100 is dE=201. Of course this same thing happens during acceleration: Only then more energy is needed. And that is not only because of the relativistic effects! >The plasma mirror avoids these difficulties. Since the mirror is >constantly being renewed at the ship's speed, the primary reflection gets >more and more efficient as the ship slows down. Yes but don't forget that the plasma gives also a serious redshift during the reflection. Also there is a finite time between replenishing the plasma and the reflection of light on that same plasma. This means the Asimov has decelerated a bit and that means the second redshift. It may be small, but it happens many many many times! Besides that, a lot of extra mass is needed to replenish the plasma. This extra mass has to be decelerated too! (Of course it get less during replenishing). Although I haven't done any calculations, I'm sure that a lot of mass is needed and my physics intuition tells me that the whole thing ends up needing the same energies as the dragon-fly. >Also, this allows us to use the plasma mirror as reaction mass at the >same time we're using it for retro reflection. plasma exhaust may not be >the most efficient in the universe, but it's the best I can find if you >want to get near C. If you use it as reaction-mass, that means that you need energy that comes from the Asimov, which it doesn't have! Also making the plasma move faster gives an even worse redshift. (If you think you can use the power of the maserbeam to accelerate the reaction-mass, then you are wrong) >How to aim a maser up the butt of the ship from twelve light years away: > >Simple really, just reflect the maser off the main sail with the focus at >one end of the core. a second mirror there re-reflects the maser up the >central core. (Foreward shows in his design a way to make diseparate >beams enter into a colimator, and emerge as one coherent beam.) I don't get this, could you make an ASCII drawing? >no furling or unfurling of the main sail is required, the whole thing can >be controlled by the secondary mirror. if it is retracted, then the >maser bounces off the main sail, imparting thrust to the ship. Without a >second mirror to bounce off of, the ship accelerates away from Sol. >To begin slow-down, (can't even call it turnaround anymore, things sure >have changed.) the secondary mirror is extended to intercept the >reflected beam and send it into the core. The beam hits a wall of >plasma, bounces off, and hits an absorber. (it can't be bounced back, >because then it would just hit the plasma again, and be going in the >wrong direction -- back toward Sol) That won't be bad, because we can use it again! (Of course more redshifted) >P.S. to Steve. I just got your analysis of the design as i was about to >send this. seems reasonably well laid out. BTW, what is the ISBN of >Taylor and Wheeler's book? that will help me to order it. It will be a >week or so before i can do any detailed work on it. ISBN 0-7167-2327-1 Timothy From popserver Mon Dec 4 21:29:56 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2177" "Mon" "4" "December" "1995" "17:35:00" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "60" "" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA04375; Mon, 4 Dec 95 08:31:27 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA13158 (5.67b/IDA-1.5 for ); Mon, 4 Dec 1995 17:34:58 +0100 Message-Id: <199512041634.AA13158@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818112256.017 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: stevev@efn.org Subject: Date: Mon, 04 Dec 1995 17:35:00 +0100 Hi Steve, Imagine two electrically charged plates, both the positively charged. These two plates are on top of each other in a gravitational field: +++++++++++++++++++ Plate 1 gravity force || +++++++++++++++++++ Plate 2 \/ -------------------------------- //////////////////////////////// Solid floor Q:Why do the plates stay apart? A:Because of the electrical field. Q:But what is an electrical field and how does it propagate? A:Photons are the cariers of the electrical field. Q:So there are photons going up and down the plates? A:Yes and no, there are virtual photons going up and down. Q:What are virtual photons? A:These are photons that have a momentum that does not correspond to its energy. They can exist due to the uncertainty principle: dp*dx=h/(4 pi) What am I trying to say? Although this situation is static (the amount of virtual photons going up equals the amount going down) there is an exchange of something. One could also say that there is just a electric field, but even then there should be something that keeps the field the way it is. It may be that this is one of the things why Kelly has a hard time understanding that it no energy is released when an object is standing on the floor. >>> If a static structure had to dissipate energy continuously to >>> remain standing, where would such energy come from? Why doesn't >>> your house fall down? Where are the batteries? >> >>The energy is coming from the gravitational attraction of the earth. It is >>disapated as heat in the structure of the house. In a structure under heavy >>loads (too heavy) you can feel the heat in the structure. > >Really? So when does the earth run out of gravity? Of course Kelly is wrong, but one could say that there is an exchange (of energy?) between the house and the Earth. The total exchange is of course zero, but in the mean time a lot of interactions are going on. Saying that there would happen nothing would not make much sense, because then Kelly is right asking what keep space-time curved. Timothy P.S. This letter is only send to you. From popserver Mon Dec 4 21:29:58 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["5186" "Mon" "4" "December" "1995" "17:34:56" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" "<199512041634.AA13144@student.utwente.nl>" "128" "Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA04398; Mon, 4 Dec 95 08:31:48 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA13144 (5.67b/IDA-1.5 for ); Mon, 4 Dec 1995 17:34:51 +0100 Message-Id: <199512041634.AA13144@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818112256.018 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Mon, 04 Dec 1995 17:34:56 +0100 ReplyFrom : Timothy ReplyTo : Kelly Subject : Humans and stairs >> Does it TAKE energy to walk down the stairs or does it GIVE energy? > >Actually both take energy since your accelerating and decelerating masses of >your body. Though obviously going down you don't need to bost yourself up a >gravity/potential energy well. When walking downstairs most of the accelerating is done by gravity, so that doesn't make you tired. Decelerating is done by the steps, so that does not take energy either. How do you respond to this? =========================================================================== ReplyFrom : Timothy ReplyTo : Kelly Subject : Using the SIM >I listed some assumptions on my Explorer Web page in LIT. I think bottom >assumption was a hydrogen atom every cubic centameter or 4. Now the question what are we going to do with the hydrogen? First catch it and decelerate a bit. Then use it both as fuel and reaction mass to decelerate even more. 4 per cubic centimetre --> 4E6 per cubic metre How much would we scoop? Total deceleration length: 2 ly = roughly 2E16 metres. 2E16*4E6*surface_of_the_scoop=8E22 hydrogen atoms per square metre of scooping area during the total deceleration. Thats a little more than one tenth MOL! and has a mass equivalent of: 0.0001 kilogram. This value seems to be too small to be useful! Unless we are planning a scoop of more than 1000 kilometres in radius. (Earth has a radius of 6500 kilometres) =========================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >Sorry that won't work. As the outer mirror moves away from the ship it has >to continuosly reshape itself to refocus on the smaller catcher mirror/sail >on the ship. I don't think refocussing is necessary, the mirror itself can be just a flat mirror so the reflected beam is nothing different than the beam from Earth. >Also without the anchor on the ship it will tend to flutter and >shift off course due to slight variations in beam, ISM, mirror reflectvity, >seperation torque, etc.. This of course ignores the fact the sail isn't >rigid, and will tend to crumple once its free of the ship. Of course the mirror has it's own "gyro-system" it can compensate slight movements by using a small side reflectors. The same principle would be used when the Asimov is accelerated by a beam. >Forward realized this, thats why he had an army of autonomus robots go with >the outer sail to keep it working. The mirror will be quite heavy so that it doesn't start moving too fast. (what is fast...) Most of that mass can be used as shielding for the mirror. Of course this whole thing would make the Asimov about twice as heavy. But that seems to be the price of any solution for deceleration. =============================================================================== ReplyTo : All ReplyFrom : Timothy Subject : nanoAI About AI and nanotech. If AI and nanotech would be sufficiently advanced in about 40 years. One or more small vessels could be send to TC all with their own fuel to decelerate. These small vessels would contain AI and nanotech or even a combination of both. This nanoAI could build the same facilities on TC that would "create" the energy for the Asimov on Earth. The advantage is that the small vessels would use much less energy to make the trip. After nanoAI has build the facilities, accelerating and decelerating the Asimov would be the same and make the whole design a lot easier. =============================================================================== ReplyTo : Steve ReplyFrom : Timothy Subject : Why use the Dragonfly >In some ways I think the Dragonfly sail (if I was sure that >Forward invented it, I would call it the Forward sail both in his >honor and for the mnemonic appropriateness) is a much cleaner and >possibly more effective design than any of the other >externally-powered ship designs that have been considered so >far. Indeed it doesn't need massive engines or difficult energy transformations. The only problem may be pointing the mirrors and beams acurately enough. What I don't see is why the mirror can't be flat. Why does it need a focusing action? As far as I can see problems about redshifts always arise if one tries to use the energy coming from Earth to decelerate the Asimov. =============================================================================== ReplyTo : Steve ReplyFrom : Timothy Subject : Lost letter? Steve, I haven't heard it from you, yet: Do we agree that at least between us the word relativistic mass is merely an other word for relativistic energy? Also in my letter of november 29th, I replied to you: >Yes, this is also true. Hot objects are heavier than cold ones >(although not by an amount we have equipment to measure). A >mirrored box full of photons is heavier than the empty box. And it doesn't matter if they all move parallel and in the same direction all the time, right? Here is another one: If two particles feel the gravity of each other, then they are heavier together than if they are separate because of the extra gravitational energy. From popserver Tue Dec 5 00:51:57 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1198" "Mon" "4" "December" "1995" "16:49:04" "-0800" "Steve VanDevender" "stevev@efn.org" nil "31" "Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA03002; Mon, 4 Dec 95 16:44:43 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id QAA13996; Mon, 4 Dec 1995 16:49:04 -0800 Message-Id: <199512050049.QAA13996@tzadkiel.efn.org> In-Reply-To: <199512041634.AA13144@student.utwente.nl> References: <199512041634.AA13144@student.utwente.nl> X-UIDL: 818124447.000 From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Mon, 4 Dec 1995 16:49:04 -0800 Timothy van der Linden writes: > ReplyTo : Steve > ReplyFrom : Timothy > Subject : Lost letter? > > Steve, I haven't heard it from you, yet: Do we agree that at > least between us the word relativistic mass is merely an other > word for relativistic energy? What you call "relativistic energy" or "relativistic mass" I call energy. I reserve the term mass for invariant mass. I believe this avoids confusion. > Also in my letter of november 29th, I replied to you: > > >Yes, this is also true. Hot objects are heavier than cold ones > >(although not by an amount we have equipment to measure). A > >mirrored box full of photons is heavier than the empty box. > > And it doesn't matter if they all move parallel and in the same direction > all the time, right? Even if the photons all move parallel in the same direction, the combination of the photons and the box is more massive than the box alone, even though the photons alone have no mass. > Here is another one: If two particles feel the gravity of each other, then > they are heavier together than if they are separate because of the extra > gravitational energy. I do not have the knowledge to answer this. From popserver Tue Dec 5 01:02:27 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["914" "Mon" "4" "December" "1995" "17:01:13" "-0800" "Steve VanDevender" "stevev@efn.org" nil "19" "Retro sailing difficulties" "^From:" nil nil "12" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA03689; Mon, 4 Dec 95 16:56:51 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.2/8.7.2) id RAA14024; Mon, 4 Dec 1995 17:01:13 -0800 Message-Id: <199512050101.RAA14024@tzadkiel.efn.org> In-Reply-To: References: <199512040714.XAA11724@tzadkiel.efn.org> X-UIDL: 818125070.002 From: Steve VanDevender To: Kevin C Houston Cc: Steve VanDevender , rddesign@wolfenet.com, Timothy van der Linden , KellySt@aol.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Retro sailing difficulties Date: Mon, 4 Dec 1995 17:01:13 -0800 Kevin C. Houston writes: > The plasma mirror avoids these difficulties. Since the mirror is > constantly being renewed at the ship's speed, the primary reflection gets > more and more efficient as the ship slows down. > > Also, this allows us to use the plasma mirror as reaction mass at the > same time we're using it for retro reflection. plasma exhaust may not be > the most efficient in the universe, but it's the best I can find if you > want to get near C. I don't think you could think of this as reaction mass as much as simply throwing out new mirrors continually so you have a backwards-reflecting mirror that stays near the speed of the ship. There is also advantage to decelerating a ship that is gradually decreasing in mass. You could just as easily talk about hucking out new mirrors periodically, rather than trying to make a plasma that has these magical reflective properties. From popserver Wed Dec 6 08:04:32 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1651" "Tue" "5" "December" "1995" "23:54:25" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "31" "Re: Retro sailing difficulties" "^From:" nil nil "12" nil "Retro sailing difficulties" nil nil] nil) Received: from mail06.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA29168; Tue, 5 Dec 95 20:55:59 PST Received: by mail06.mail.aol.com (8.6.12/8.6.12) id XAA10544; Tue, 5 Dec 1995 23:54:25 -0500 Message-Id: <951205235424_45961101@mail06.mail.aol.com> X-UIDL: 818237001.008 From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org Cc: rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Retro sailing difficulties Date: Tue, 5 Dec 1995 23:54:25 -0500 >> if anyone can figure out how to bounce the maser beam back >> toward TC after it hits the plasma, I'll gladly scrap the >> accelerating-the-plasma with-the-converted-energy idea. >> which would save us from having to use microwaves, and >> help out with our heat load. Arange the catcher mirror so that it focuses the reflected maser beam (from the ring sail) on the plasma, but does not inact with the maser reflected back from the plasma. If that reflected maser beam hits a flat mirror (or a curved or conical mirror) that doesn't reflect it onto the ring sail. The reflection from the plasma will push backwards toward Sol. I thought of a problem with the ring sail thou. It would focus the maser ahead of the ship. To realize this think of the thrust vectors on the sail from the reflections, vs the vectors from the cables from the ship. If the thrust vector angles are angled more forward than the cables, they would pull the sail forward. Which would colapse the sail. Since the reflected maser beams would be angled ahead of the normal vector at the point of reflection (equal angles of incidence and reflection) They would focus even farther ahead of the ship. I had thought of a was of using another sail to reflect the masers back outward for collection behind the ship, but that would probably not work due to beam reflections off the plasma stream. I suppose you could have the beam interact with the injected plasma in front of the ship. This would blow the high energy plasma stream backwards toward the ship. For later reflection off a magnetically or electrostatically charged forward shield/pusher plate. Kelly From popserver Wed Dec 6 08:04:33 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4359" "Tue" "5" "December" "1995" "23:54:56" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "97" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Received: from emout05.mail.aol.com by efn.efn.org (4.1/smail2.5/05-07-92) id AA29177; Tue, 5 Dec 95 20:56:02 PST Received: by emout05.mail.aol.com (8.6.12/8.6.12) id XAA14724; Tue, 5 Dec 1995 23:54:56 -0500 Message-Id: <951205235454_45961665@emout05.mail.aol.com> X-UIDL: 818237001.009 From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 5 Dec 1995 23:54:56 -0500 ReplyFrom : Timothy ReplyTo : Kelly Subject : Using the SIM >I listed some assumptions on my Explorer Web page in LIT. I think bottom >assumption was a hydrogen atom every cubic centameter or 4. Now the question what are we going to do with the hydrogen? First catch it and decelerate a bit. Then use it both as fuel and reaction mass to decelerate even more. 4 per cubic centimetre --> 4E6 per cubic metre How much would we scoop? Total deceleration length: 2 ly = roughly 2E16 metres. 2E16*4E6*surface_of_the_scoop=8E22 hydrogen atoms per square metre of scooping area during the total deceleration. Thats a little more than one tenth MOL! and has a mass equivalent of: 0.0001 kilogram. This value seems to be too small to be useful! Unless we are planning a scoop of more than 1000 kilometres in radius. (Earth has a radius of 6500 kilometres) =========================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >Sorry that won't work. As the outer mirror moves away from the ship it has >to continuosly reshape itself to refocus on the smaller catcher mirror/sail >on the ship. >> I don't think refocussing is necessary, the mirror itself can >> be just a flat mirror so the reflected beam is nothing >> different than the beam from Earth. That would mean the catcher sail on the ship would be the same size as the reflector mirror. That would mean it would get more push forward from the dirrect beam from earth, than push back from the reflected beam from the mirror. Assuming of course the mirror flies sideway slightly so it isn't in the ships shaddow all the way to Tau. Of course if its off to one side you have to turn it so its reflections tracks the ship, so your back to the tracking problem. >Also without the anchor on the ship it will tend to flutter and >shift off course due to slight variations in beam, ISM, mirror reflectvity, >seperation torque, etc.. This of course ignores the fact the sail isn't >rigid, and will tend to crumple once its free of the ship. >> Of course the mirror has it's own "gyro-system" it can >> compensate slight movements by using a small side >> reflectors. The same principle would be used when the >> Asimov is accelerated by a beam. With enough accuracy to hit the retro sail at a distence of light years? ============================================================================== = ReplyTo : All ReplyFrom : Timothy Subject : nanoAI >> About AI and nanotech. If AI and nanotech would be >> sufficiently advanced in about 40 years. One or more >> small vessels could be send to TC all with their >> own fuel to decelerate. These small vessels would >> contain AI and nanotech or even a combination of both. >> This nanoAI could build the same facilities on TC that >> would "create" the energy for the Asimov on Earth. The >> advantage is that the small vessels would use much less >> energy to make the trip. After nanoAI has build the >> facilities, accelerating and decelerating the Asimov >> would be the same and make the whole design a lot easier. We still have no drive idea that could get a bit or small ship to Tau C. We've added the relyability problems of the AI and Nano systems to the project. After all, programs can crash, and nano's are made of complex molecules that might break down in the high radiation in transite. Assuming they get there in tact, what do we tel them to use for resources in a system we don't know anything about? How does a ship fly in two apposing beams? You can't turn eiather off. Since: you can't contact the ship to know what its doing in time, and don't want to fly to a system in the hopes the A.I's will turn the beam on when you expect. We also have extended the time of the project to us sustainable levels. Figure a quarter century after launch before a returning beam from Tau C. announces the decel system is compleated. Then a quarter century after that (50 years from the launch of the first nano ship), a beam from your starship announces you've started exploration. If the projects going to take that long you might as well wait untill you have a better drive system. For that matter. If the A.I's are good enough to build the decel gear. You might as well have them do the exploration and skip the human ship. From popserver Wed Dec 6 21:11:32 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5589" "Wed" "6" "December" "1995" "22:02:09" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "131" "Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Received: from student.utwente.nl (driene.student.utwente.nl) by efn.efn.org (4.1/smail2.5/05-07-92) id AA16443; Wed, 6 Dec 95 13:02:37 PST Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA28198 (5.67b/IDA-1.5 for ); Wed, 6 Dec 1995 22:01:53 +0100 Message-Id: <199512062101.AA28198@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-UIDL: 818284229.000 From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Wed, 06 Dec 1995 22:02:09 +0100 Who anyone who likes a physics comic, try: http://www.cpedu.rug.nl/~N0642983/velcro.gif It's about 14 Kbyte ============================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >>> I don't think refocussing is necessary, the mirror itself can >>> be just a flat mirror so the reflected beam is nothing >>> different than the beam from Earth. > >That would mean the catcher sail on the ship would be the same size as the >reflector mirror. That would mean it would get more push forward from the >dirrect beam from earth, than push back from the reflected beam from the >mirror. Hmm, yes, but there seems to have a similar problem with the plasma mirror. But I've found a solution: /\ A / \ B Two mirrors A and B at a perpendicular angle /________\ /|__________|\ / || || \ || || || || || /\ \/ Beam from Earth Beam to Earth This design makes the total mirror about 3 times bigger. The beam from Earth should be directed mainly on mirror B so that the beam to the Earth (or from TC) is reflected mainly from A. The final result is that there are two beams next to each other, one is going up the other is going down. >Assuming of course the mirror flies sideway slightly so it isn't in >the ships shaddow all the way to Tau. Of course if its off to one side you >have to turn it so its reflections tracks the ship, so your back to the >tracking problem. With this new design the biggest tracking problem is removed. Furthermore the Asimov always has to follow the beam just as in the acceleration fase. >>Also without the anchor on the ship it will tend to flutter and >>shift off course due to slight variations in beam, ISM, mirror reflectvity, >>seperation torque, etc.. This of course ignores the fact the sail isn't >>rigid, and will tend to crumple once its free of the ship. > >>> Of course the mirror has it's own "gyro-system" it can >>> compensate slight movements by using a small side >>> reflectors. The same principle would be used when the >>> Asimov is accelerated by a beam. > >With enough accuracy to hit the retro sail at a distence of light years? 10 ly, 30 ly does it really matter? The minimum is 10 ly for any kind of beam-propulsion system. I wonder if an extra 20 ly makes that much difference. ============================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : nanoAI >We still have no drive idea that could get a bit or small ship to Tau C. We have ideas, the biggest problem is the enormous amounts of fuel that are needed. Lets say we use a take-all-fuel-with-you system. For matter&anti-matter fuel the ratio fuel:ship would be about 20:1 for small ships 1E4 1E5 kg this may be acceptable but for ships 1E8 or 1E9 kg its a completly different story. >We've added the relyability problems of the AI and Nano systems to the >project. After all, programs can crash, and nano's are made of complex >molecules that might break down in the high radiation in transite. Assuming >they get there in tact, what do we tel them to use for resources in a system >we don't know anything about? Indeed things can go wrong and will go wrong. So will things happen on a ship like the Asimov, only then people are endangered. High radiation as a cause of error can easely be prevented by sufficient shielding. We know that there will be asteroids and planets there. This means that all the basic materials should be present, so our mini factories have to find them an use them. >How does a ship fly in two apposing beams? You can't turn eiather off. > Since: you can't contact the ship to know what its doing in time, and don't >want to fly to a system in the hopes the A.I's will turn the beam on when you >expect. The beams should be slightly from parallel. Halfway the should cross, and the vessel using it has to change beams there. This means that it has to move "side-way" some 100-1000 km or so. It should be like changing rail-tracks by using a switch. >We also have extended the time of the project to us sustainable levels. > Figure a quarter century after launch before a returning beam from Tau C. >announces the decel system is compleated. Then a quarter century after that >(50 years from the launch of the first nano ship), a beam from your starship >announces you've started exploration. If the projects going to take that >long you might as well wait untill you have a better drive system. Supposing a significant better system is possible within 50 extra years, I think its worth the waiting. >For that matter. If the A.I's are good enough to build the decel gear. You >might as well have them do the exploration and skip the human ship. That is something completly different discussion: Why do we want to go there anyway. I was having a discussion with Nick Tosh about that, until his connection broke down. I can tell you, that I don't know why we want to go there so soon anyway. If you have an answer I'd like to know... For the AI and nano, if they will be as unreliable and unadvanced as you think, my guess is that the time isn't right for flying to TC anyway: If anything, and I mean anything goes wrong in a system that uses 1E17 Watts you are lost! It's not like you can cut the power any time you like. What I wrote about overheating is just a small example of the problems that go with these power streams. (And as far as I'm concerned that problem isn't solved yet) Timothy From popserver Sat Dec 9 05:41:15 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7364" "Fri" "8" "December" "1995" "21:34:28" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "197" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout04.mail.aol.com (emout04.mail.aol.com [198.81.10.12]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id VAA04907 for ; Fri, 8 Dec 1995 21:38:07 -0800 (PST) Received: by emout04.mail.aol.com (8.6.12/8.6.12) id VAA06888; Fri, 8 Dec 1995 21:34:28 -0500 Message-ID: <951208213427_67925326@emout04.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu Subject: Re: Engineering Newsletter Date: Fri, 8 Dec 1995 21:34:28 -0500 Hi guys, a few web pages you might be interested in. Zenon suggested nanotech and A.I. might be a pre req for star travel. He also suggested for more info about significance of nanotech for space exploration. See the Molecular Manufacturing Shortcut Group page at: http://www.music.qub.ac.uk:80/~amon/IslandOne/MMSG/ --------------- For serious info on planing space flights, check out: > >http://oel-www.jpl.nasa.gov/basics/bsf.htm > Originally created as an internal JPL training document, the Basics of Spaceflight is comprehensive, medium level overview of a wide range of topics related to construction and operation of planetary spacecraft. The material is supposed to be extremely well written and unlike many NASA outreach and educational materials, has not been digested down to the 5th grade level. ----------------------- Larry Klaes Editor of SETIQuest Magazine recomends http://www.setiquest.com It is still under construction, but its trying to let you explore how a starship will interact while approaching light speed. It can be found at URL http://www.fourmilab.ch under the link cship. ---------------------------------------------------------------------- ============================================================================== ReplyTo: Timothy Subject : Plasma mirror >>> I don't think refocussing is necessary, the mirror itself can >>> be just a flat mirror so the reflected beam is nothing >>> different than the beam from Earth. > >>That would mean the catcher sail on the ship would be the same size as the >>reflector mirror. That would mean it would get more push forward from the >>dirrect beam from earth, than push back from the reflected beam from the >>mirror. >Hmm, yes, but there seems to have a similar problem with >the plasma mirror. Not really, Since the ring sail & catcher mirror are in the same place (attached to the ship) the ring sial would be geting the same energy (no energy drop due to r^2 losses.) >But I've found a solution: /\ A / \ B Two mirrors A and B at a perpendicular angle /________\ /|__________|\ / || || \ || || || || || /\ \/ Beam from Earth Beam to Earth > This design makes the total mirror about 3 times bigger. >The beam from Earth should be directed mainly on mirror B > so that the beam to the Earth (or from TC) is reflected >mainly from A. The final result is that there are two beams > next to each other, one is going up the other is >going down. Whats the advantage? Also you seem to asume the that the power beam will be as small as the miror? It sould be thousands of miles across. >>Assuming of course the mirror flies sideway slightly so it isn't in >>the ships shaddow all the way to Tau. Of course if its off to one side you >>have to turn it so its reflections tracks the ship, so your back to the >>tracking problem. >With this new design the biggest tracking problem is removed. Furthermore >the Asimov always has to follow the beam just as in the acceleration phase. I don't understand what your going for. >>Also without the anchor on the ship it will tend to flutter and >>shift off course due to slight variations in beam, ISM, mirror reflectvity, >>seperation torque, etc.. This of course ignores the fact the sail isn't >>rigid, and will tend to crumple once its free of the ship. > >>> Of course the mirror has it's own "gyro-system" it can >>> compensate slight movements by using a small side >>> reflectors. The same principle would be used when the >>> Asimov is accelerated by a beam. > >With enough accuracy to hit the retro sail at a distence of light years? >>10 ly, 30 ly does it really matter? The minimum is 10 ly for >> any kind of >> beam-propulsion system. I wonder if an extra 20 ly makes that much difference. ============================================================================== ReplyTo : Timothy Subject : nanoAI >>We still have no drive idea that could get a bit or small ship to Tau C. >We have ideas, the biggest problem is the enormous amounts >of fuel that are needed. Lets say we use a >take-all-fuel-with-you system. For matter&anti-matter fuel > the ratio fuel:ship would be about 20:1 for small ships 1E4 >1E5 kg this may be acceptable but for ships 1E8 or 1E9 kg >its a completly different story. Your taking hundreds of tons of antimatter! That is a stagering amount to manufacture, or even hold on to! >>We've added the relyability problems of the AI and Nano systems to the >>project. After all, programs can crash, and nano's are made of complex >>molecules that might break down in the high radiation in transite. Assuming >>they get there in tact, what do we tel them to use for resources in a system >>we don't know anything about? >Indeed things can go wrong and will go wrong. So will things happen on a >ship like the Asimov, only then people are endangered. >High radiation as a cause of error can easely be prevented by >sufficient shielding. People are mentally much more adaptable and relyable than any current Nano/A.I. systems. >We know that there will be asteroids and planets there. This >means that all the basic materials should be present, so our >mini factories have to find them an use them. Thats a big job if your the size of a virus. -------- >>We also have extended the time of the project to un sustainable levels. >> Figure a quarter century after launch before a returning beam from Tau C. >>announces the decel system is compleated. Then a quarter century after that >>(50 years from the launch of the first nano ship), a beam from your starship >>announces you've started exploration. If the projects going to take that >>long you might as well wait untill you have a better drive system. >Supposing a significant better system is possible within 50 > extra years, I think its worth the waiting. So will the backers. So the nano idea won't be launched, and the idea isn't feasable. >>For that matter. If the A.I's are good enough to build the decel gear. You >>might as well have them do the exploration and skip the human ship. >That is something completly different discussion: Why do we >want to go there anyway. I was having a discussion with Nick > Tosh about that, until his connection broke down. I can tell > you, that I don't know why we want to go there so soon >anyway. >If you have an answer I'd like to know... As I remember the idea of LIT was to see if we could think of some way we could build a starship in 2050 with probable technology of the day. Tau C was selected as a target to focus the groups attention on. >For the AI and nano, if they will be as unreliable and > unadvanced as you think, my guess is that the time isn't right >for flying to TC anyway: If anything, and I mean anything goes >wrong in a system that uses 1E17 Watts you are lost! It's not >like you can cut the power any time you like. What I wrote >about overheating is just a small example of the problems >that go with these power streams. (And as far as I'm >concerned that problem isn't solved yet) Agreed. I remember a demo where a steelwool pad was throw in a radar beam. It burned away in secounds. Very impresive! Especially to someone who might be thinking of riding such a beam for a couple decades. Kelly From popserver Sat Dec 9 17:40:31 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6788" "Sat" "9" "December" "1995" "17:38:50" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "173" "Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id IAA29840 for ; Sat, 9 Dec 1995 08:38:06 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA11787 (5.67b/IDA-1.5 for ); Sat, 9 Dec 1995 17:38:48 +0100 Message-Id: <199512091638.AA11787@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Engineering Newsletter Date: Sat, 09 Dec 1995 17:38:50 +0100 ReplyTo : Kelly ReplyFrom : Timothy Subject : Plasma mirror >>>> I don't think refocussing is necessary, the mirror itself can >>>> be just a flat mirror so the reflected beam is nothing >>>> different than the beam from Earth. >> >>>That would mean the catcher sail on the ship would be the same size as the >>>reflector mirror. That would mean it would get more push forward from the >>>dirrect beam from earth, than push back from the reflected beam from the >>>mirror. > >>Hmm, yes, but there seems to have a similar problem with >>the plasma mirror. > >Not really, Since the ring sail & catcher mirror are in the same place >(attached to the ship) the ring sial would be geting the same energy (no >energy drop due to r^2 losses.) But would the beam from Earth not strike the ring sail? If not, please could you make an (ASCII)drawing, because then I don't understand how where the ring-sail and catcher mirror and the plasma are located. I don't use a ring-sail AND a catcher mirror, during deceleration, I have only one flat mirror directed to TC on the ship and a retro-mirror that is not coupled to the ship. A|----\ O-----------/ O Earth ----------- Beam from Earth \ / Retro-mirror ---- Beam from TC (Beam from Earth reflected by the retro-mirror) A| Asimov with a flat mirror >> This design makes the total mirror about 3 times bigger. >>The beam from Earth should be directed mainly on mirror B >> so that the beam to the Earth (or from TC) is reflected >>mainly from A. The final result is that there are two beams >> next to each other, one is going up the other is >>going down. >Whats the advantage? It overcomes the problem you mentioned: tracking. The only thing the Asimov has to do is move about 1000 kilometres to the left after it has uncoupled the retro-mirror. The result is that the mirror and the Asimov will move in the same direction during deceleration. >Also you seem to asume the that the power beam will be as small as the miror? >It sould be thousands of miles across. I indeed did, if the beam is much bigger than the mirror, that would really be a waste. If the radius of the beam is twice as big as the radius of the mirror that would mean a loss of 75% of the beam! But to overcome this if the beam is misplaced or bigger than the mirror, my design could be modified a bit: Beam that missed the mirror || || / || \ A / || \ B Two mirrors A and B at a perpendicular angle /__________________\ but at some distance from each other /|____________________|\ / || || || \ || || || || || || || /\ /\ \/ Beams from Earth Beam to Earth Although the mirrors are further apart, they still would be connected to each other, only the connections will not reflect much. >>>Assuming of course the mirror flies sideway slightly so it isn't in >>>the ships shaddow all the way to Tau. Of course if its off to one side you >>>have to turn it so its reflections tracks the ship, so your back to the >>>tracking problem. > >>With this new design the biggest tracking problem is removed. Furthermore >>the Asimov always has to follow the beam just as in the acceleration phase. > >I don't understand what your going for. See above. You said that a retro-mirror had tracking problems because it always had to be at an angle with the Asimov. My new design overcomes this problem ============================================================================== ReplyTo : Kelly ReplyFrom : Timothy Subject : nanoAI >>We have ideas, the biggest problem is the enormous amounts >>of fuel that are needed. Lets say we use a >>take-all-fuel-with-you system. For matter&anti-matter fuel >> the ratio fuel:ship would be about 20:1 for small ships 1E4 >1E5 kg this >may be acceptable but for ships 1E8 or 1E9 kg >>its a completly different story. > >Your taking hundreds of tons of antimatter! That is a stagering amount to >manufacture, or even hold on to! My assumptions are that making anti-matter in 50 years will be about 50% efficient. Of course I can't be sure of this, but why wouldn't it? (Rethorical question) Besides this efficiency, I wonder why you are so blaffed by these numbers. These numbers are just the sum of the energy needed during 1 or 2 years of acceleration. If we build a maser beaming station, a similar amount of energy is needed. The only thing you do when transferring energy to anti-matter is making it a bit more permanent. It probably is the easiest way to store such amounts of energy. So the moral is, anti-matter is merely an amount of energy that is easier to keep in storage. >People are mentally much more adaptable and relyable than any current >Nano/A.I. systems. You can't compare adaptability and reliable to CURRENT systems. That would be the same as to say that current engines would not work for our project and thus that it was not possible. >>We know that there will be asteroids and planets there. This >>means that all the basic materials should be present, so our >>mini factories have to find them an use them. > >Thats a big job if your the size of a virus. >From this I can conclude that I have a more optimistic view about nanotech and AI, then you do. Of course nanotech and AI are now in an early stage, but if 50 years ago, you had said what computers of today would be like, then they had laughed at you also. >>That is something completly different discussion: Why do we >>want to go there anyway. I was having a discussion with Nick >>Tosh about that, until his connection broke down. I can tell >>you, that I don't know why we want to go there so soon >>anyway. >>If you have an answer I'd like to know... > >As I remember the idea of LIT was to see if we could think of some way we >could build a starship in 2050 with probable technology of the day. Tau C >was selected as a target to focus the groups attention on. I know that, but I thought it was interesting to figure out why we want to go there. Is it just to have pissed on the ground there? Or is it because we want to colonize it? Or is it for scientific reasons? Or maybe all of them? All these things me be reasonable at first but, if you think a bit further, they make not much sense anymore... >Agreed. I remember a demo where a steelwool pad was throw in a radar beam. > It burned away in secounds. Very impresive! Especially to someone who >might be thinking of riding such a beam for a couple decades. I wish I could have seen it. Bear in mind that what you saw there was probably as very small example of what may be the case for the Asimov. Timothy From popserver Tue Dec 12 18:04:49 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["10319" "Tue" "12" "December" "1995" "00:03:44" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "239" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id VAA28152 for ; Mon, 11 Dec 1995 21:04:34 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id AAA05472; Tue, 12 Dec 1995 00:03:44 -0500 Message-ID: <951211233058_51562464@emout06.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu, kgstar@most.fw.hac.com Subject: Re: Engineering Newsletter Date: Tue, 12 Dec 1995 00:03:44 -0500 Kelly re: Timothy Subject : Plasma mirror >> >>>> I don't think refocussing is necessary, the mirror itself can >> >>>> be just a flat mirror so the reflected beam is nothing >> >>>> different than the beam from Earth. >> >> >> >>>That would mean the catcher sail on the ship would be the same size as the >> >>>reflector mirror. That would mean it would get more push forward from the >> >>>direct beam from earth, than push back from the reflected beam from the >> >>>mirror. >> > >> >>Hmm, yes, but there seems to have a similar problem with >> >>the plasma mirror. >> > >> >Not really, Since the ring sail & catcher mirror are in the same place >> >(attached to the ship) the ring sail would be getting the same energy (no >> >energy drop due to r^2 losses.) >> >> But would the beam from Earth not strike the ring sail? >> If not, please could you make an (ASCII)drawing, because then I don't >> understand how where the ring-sail and catcher mirror and the plasma are >> located. Yes, the beam strikes the ring sail, and is reflected backward (Sol ward) and inward toward a small catcher mirror. The beam is then reflected forward from the catcher mirror to the plasma mirror. Net fore-aft thrust is nil until after it reflects off the plasma mirror. >> >> I don't use a ring-sail AND a catcher mirror, during deceleration, I have >> only one flat mirror directed to TC on the ship and a retro-mirror that is >> not coupled to the ship. A|----\ O-----------/ O Earth ----------- Beam from Earth \ / Retro-mirror ---- Beam from TC (Beam from Earth reflected by the retro-mirror) A| Asimov with a flat mirror >> >> This design makes the total mirror about 3 times bigger. >> >>The beam from Earth should be directed mainly on mirror B >> >> so that the beam to the Earth (or from TC) is reflected >> >>mainly from A. The final result is that there are two beams >> >> next to each other, one is going up the other is >> >>going down. >> >> >Whats the advantage? >> >> It overcomes the problem you mentioned: tracking. >> The only thing the Asimov has to do is move about 1000 kilometers to the >> left after it has uncoupled the retro-mirror. The result is that the mirror >> and the Asimov will move in the same direction during deceleration. You still haven't dealt with the problems of a drop mirror. - Given that the point of the exercise is that the mirror and ship will accelerate apart until they are moving apart at nearly light speed. They will be getting very far apart, and the "Retro-mirror" will need to aim to track the decelerating ship. By having the ships flat reflector mirror the size of the full power mirrors you eliminate the retro-mirror needs to focus, but not to keep aiming at the retreating ship. In trade you've added increased need for structural material, and added extra forward thrust from the earth beam on the back of the ship. (I don't by the ship running on a tiny beam that just fits in the sail. The ship will need to maneuver, and the transmitters couldn't hope to generate that much accuracy.) - The energy retuning to ship will drop off like a rock as the distance between ship and retro or drop mirror increases. Given that the mirror will not be that smooth (it will probably be rippling) the beam will be diverging badly after it reflects. - Need for active control systems on drop mirror. - Need for structural stiffening on drop mirror. ============================================================================== Kelly re: Timothy Subject : nanoAI >> >>We have ideas, the biggest problem is the enormous amounts >> >>of fuel that are needed. Lets say we use a >> >>take-all-fuel-with-you system. For matter&anti-matter fuel >> >> the ratio fuel:ship would be about 20:1 for small ships 1E4 >1E5 kg this >> >may be acceptable but for ships 1E8 or 1E9 kg >> >>its a completely different story. >> > >> >Your taking hundreds of tons of antimatter! That is a staggering amount to >> >manufacture, or even hold on to! >> >> My assumptions are that making anti-matter in 50 years will be about 50% >> efficient. Of course I can't be sure of this, but why wouldn't it? >> (Rethorical question) >> Besides this efficiency, I wonder why you are so blaffed by these numbers. >> These numbers are just the sum of the energy needed during 1 or 2 years of >> acceleration. >> If we build a maser beaming station, a similar amount of energy is needed. >> The only thing you do when transferring energy to anti-matter is making it a >> bit more permanent. It probably is the easiest way to store such amounts of >> energy. >> >> So the moral is, anti-matter is merely an amount of energy that is easier to >> keep in storage. Easier? The ship would still need to carry something like its own weight in matter anti-mater. A mass of thousands to millions of tons. Forward was hoping optimistically we'd be able to routinely generate and store milligrams to grams of antimatter. >> >> >People are mentally much more adaptable and reliable than any current >> >Nano/A.I. systems. >> >> You can't compare adaptability and reliable to CURRENT systems. That would >> be the same as to say that current engines would not work for our project >> and thus that it was not possible. True, but since no current A.I. system works very well, and no nano-tech systems work at all, I'd have a very hard time expecting them to be developed to that degree of reliability in 50 years. Its out there with the "we discover warp drive possibilities". Sooner or later we'll do them, or something like them; but they don't fit within LITs "no radical new tech" parameters >> From this I can conclude that I have a more optimistic view about nanotech >> and AI, then you do. >> Of course nanotech and AI are now in an early stage, but if 50 years ago, >> you had said what computers of today would be like, then they had laughed at >> you also. 50 years ago we had production computers. Only a handful, and their capacities were trivial be current standards; but thats farther than Nano/A.I. systems, and no current computer or automation system could attempt anything on the scale of what you are suggesting >> >>That is something completely different discussion: Why do we >> >>want to go there anyway. I was having a discussion with Nick >> >>Tosh about that, until his connection broke down. I can tell >> >>you, that I don't know why we want to go there so soon >> >>anyway. >> >>If you have an answer I'd like to know... >> > >> >As I remember the idea of LIT was to see if we could think of some way we >> >could build a starship in 2050 with probable technology of the day. Tau C >> >was selected as a target to focus the groups attention on. >> >> I know that, but I thought it was interesting to figure out why we want to >> go there. Is it just to have pissed on the ground there? Or is it because we >> want to colonize it? Or is it for scientific reasons? Or maybe all of them? >> All these things me be reasonable at first but, if you think a bit further, >> they make not much sense anymore... True. The LIT project assumed a big (blank check) push to go to Tau, but no reason or goal was given, and the group has never been able to agree on one. Thats a pretty big hole in the discussion, but since we also can't figure out how to get there in the first place its kind of a mute point. One thing I was considering was what we can do. My Explorer design could certainly be able to carry enough fusion fuel to decelerate from 1/10th C. Marshal Savage mention something like a 20 to 1 fuel to ship mass ration to do that. I'd like to check that, but for the moment will assume its true. Obviously trying to do that at 2/10ths C would take 20 squared (400) ship masses of fuel. So thats out, but at even those speeds drag is a serious factor. Savages book mentions that at near light speed the (one atom per cubic centimeter) inter-stellar Medium could cause up to 37 milligrams of drag pressure per square centimeter of frontal area. I'd like to work up the numbers for various interstellar densities and ship speeds; but it seems likely that some kind of magnetic or electrostatic, scoop or parachute could give us a big amount of breaking force. If we stay with a .1 to .2 C top speed ship we might be able to get a practical mission to some of the nearer stars. Not Tau C, but Alpha Centuri, Barnard's, Rigil Kent (Rigel kent A is a G2 yellow Main star at 4.4 LY, B is a K6 orange-main at 4.4). A .2 C ship could get there in a usable period of time. A version of my Explorer Fusion design could get there and back. If you have some reason of wanting to go there regularly. The first ship could assemble automated fuel launchers in the target systems. That would allow lighter ships to make the same run at higher speeds without carrying heavy fuel loads. (Assuming they trusted the fuel launcher at the receiving system to answer their launch command.) I suppose launching construction/survey flights might be practical (i.e someone might be willing to pay for them.) if they could be kept down to that length of time, and the public had an interests in the stars similar to the Apollo days. But what do we do there that would interest people that much? Science seems a pretty thin reason. Colonies can be built in this solar system just as well as another. Apollo was run for the international prestige (specifically vs the Soviets). I can't see anyone coming up to threaten a specific group that much by 2050; but even without that the project might attract enough enthusiasm among a major country to fund it. (My experience on International space projects makes me discount them out of hand.) So I guess what we want to do there is a question that we'd need to resolve. More specifically why we'ld feel we needed to do it then? If you willing to wait another half century. You could expect to have relyable equipment based on physics unknown to us now. (Matter conversion? Time space distortion? Such things have been seriously proposed.) Kelly From popserver Tue Dec 12 18:11:19 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1935" "Tue" "12" "December" "1995" "09:19:36" "-0500" "Kelly Starks" "kgstar@most.magec.com" nil "45" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: kgstar@most.magec.com Received: from most.magec.com (gw1.magec.com [151.168.2.3]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id GAA16681 for ; Tue, 12 Dec 1995 06:25:27 -0800 (PST) Received: by most.magec.com (4.1/SMI-4.1) id AA16294; Tue, 12 Dec 95 09:22:04 EST Received: from unknown(151.168.254.82) by gw1 via smap (V1.3mjr) id smI016212; Tue Dec 12 09:20:33 1995 Received: by most (4.1/SMI-4.1) id AA02033; Tue, 12 Dec 95 09:20:30 EST Received: from ss4.magec.com(151.168.145.199) by most via smap (V1.5khhunt) id sma002022; Tue Dec 12 09:19:39 1995 Received: from [151.168.158.72] by ss4.uiv (4.1/SMI-4.1) id AA01252; Tue, 12 Dec 95 09:19:35 EST X-Sender: kgstar@pophost.magec.com Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: kgstar@most.magec.com (Kelly Starks x7066 MS 10-39) To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu, kgstar@most.magec.com Subject: Re: Engineering Newsletter Date: Tue, 12 Dec 1995 09:19:36 -0500 Ram mass? Ram Scoop collector 1000 km diameter scoop 200 tons. The speed of light is 300,000 kilometers per second Assuming your moving at 1/3rd the speed of light (100,000 kilometer per second, or 1E10 cm/sec) with a scoop area of 1000 km (pi*R^2=pi(50,000,000cm)^2 = 7.854E15 cm^2). You'd be scooping up the mass in 7.854 E25 cubic centimeters of space. A big question is the composition of interstellar space. A classic assumption is that there is nothing but about 1 atom of hydrogen in a cubic centimeter of space. More recently, people guess it might be less than .054 atoms per cubic centimeter or as many as 10. Even more recently than that (say the last few months) it has been proposed that there may be a lot of long-chain carbon molecules in space. Perhaps 60-200 atoms / molecules. These small, dark, heavy molecules might be the missing 90-99% of the mass of the galaxy (euphemistically called "dark matter"). So far, no one really knows. This is unfortunate, because the composition of the interstellar medium makes a hell of a difference in the design of a RAIR-based starship. Since we don't know one way or the other, let's assume one atom per cubic centimeter at a proton mass of 1.673 E-27 Kg. At 0.333c, using the above design figures, our 1000 km in diameter scoop, scoops up a ram flow of 131.4 grams per second. thats 473 kilos per hour 4.14 million kilos per year. Given a ship weighing hundreds of times that. This isn't going to slow us down much. Of course the mass of inter stellar medium is hotly debated. Some give numbers 100 times heavyer, but others think its much less. ---------------------------------------------------------------------- Kelly Starks Internet: kgstar@most.magec.com Sr. Systems Engineer Magnavox Electronic Systems Company (Magnavox URL: http://www.magec.com/external.html) ---------------------------------------------------------------------- From popserver Thu Dec 14 18:07:49 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2216" "Wed" "13" "December" "1995" "19:18:32" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "44" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail06.mail.aol.com (mail06.mail.aol.com [152.163.172.108]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id QAA07839 for ; Wed, 13 Dec 1995 16:20:01 -0800 (PST) Received: by mail06.mail.aol.com (8.6.12/8.6.12) id TAA24227; Wed, 13 Dec 1995 19:18:32 -0500 Message-ID: <951213191826_72201277@mail06.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, david@interworld.com, MLEN3097@mercury.gc.peachnet.edu Subject: Re: Engineering Newsletter Date: Wed, 13 Dec 1995 19:18:32 -0500 We were talking about how much drag we might be able to get out of the interstellar medium. I dug some old numbers out of my LIT web page and tinkered with them. Note that my numbers were for 1.3rd light speed, so I didn't bother with relativity corrections. Kelly Starks ================================================== Ram Scoop collector 1000 km diameter scoop 200 tons. The speed of light is 300,000 kilometers per second Assuming your moving at 1/3rd the speed of light (100,000 kilometer per second, or 1E10 cm/sec) with a scoop area of 1000 km (pi*R^2=pi(50,000,000cm)^2 = 7.854E15 cm^2). You'd be scooping up the mass in 7.854 E25 cubic centimeters of space. A big question is the composition of interstellar space. A classic assumption is that there is nothing but about 1 atom of hydrogen in a cubic centimeter of space. More recently, people guess it might be less than .054 atoms per cubic centimeter or as many as 10. Even more recently than that (say the last few months) it has been proposed that there may be a lot of long-chain carbon molecules in space. Perhaps 60-200 atoms / molecules. These small, dark, heavy molecules might be the missing 90-99% of the mass of the galaxy (euphemistically called "dark matter"). So far, no one really knows. This is unfortunate, because the composition of the interstellar medium makes a hell of a difference in the design of a RAIR-based starship. Since we don't know one way or the other, let's assume one atom per cubic centimeter at a proton mass of 1.673 E-27 Kg. At 0.333c, using the above design figures, our 1000 km in diameter scoop, scoops up a ram flow of 131.4 grams per second. thats 473 kilos per hour 4.14 million kilos per year. (4,140 metric tons per year.) Given a ship weighing hundreds of times that. This isn't going to slow us down much. But if we want to assume lots of carbon molecules, the mass could jump up to the mass of the ship per year. But thats probably a bad assumption here near Sol. Seems this area of the galaxy is in a big bubble of space blasted nearly clean of debries by a recent supernova. So we may be living in one of the worst areas of the galaxy for a ramscoop, or ram breaked, starship. Kelly From popserver Thu Dec 14 19:13:04 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7390" "Thu" "14" "December" "1995" "20:09:36" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "142" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id LAA12543 for ; Thu, 14 Dec 1995 11:08:54 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA03098 (5.67b/IDA-1.5 for ); Thu, 14 Dec 1995 20:09:29 +0100 Message-Id: <199512141909.AA03098@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Thu, 14 Dec 1995 20:09:36 +0100 Timothy re: Kelly Subject : Plasma mirror >You still haven't dealt with the problems of a drop mirror. > - Given that the point of the exercise is that the mirror and ship will >accelerate apart until they are moving apart at nearly light speed. They >will be getting very far apart, and the "Retro-mirror" will need to aim to >track the decelerating ship. By having the ships flat reflector mirror the >size of the full power mirrors you eliminate the retro-mirror needs to focus, >but not to keep aiming at the retreating ship. "Very far" would be something like 2 ly: The mirror and the ship will be furthest apart when the Asimov has decelerated and is near TC. It takes approximately 8 years to decelerate the Asimov. The mirror never exceeds the speed of light and thus travels about 8 ly. It is released from the Asimov when 6 ly from TC. So after 8 years the Asimov has decelerated and is near TC. The mirror is then thus 2 ly further than TC and the Asimov. So the extra distance is not so much as you would think. But of course still the problem of aiming is there. I've no solution other than some gyro-system. But what I don't understand is what is the difference between aiming the beam that comes from Earth and the beam that comes from the retro-mirror? The only thing the retro-mirror has to do is not turn, so it does not have to aim but just not have to turn. Do you know what the difference is between aiming the beam from Earth and aiming from the retro-mirror? > In trade you've added increased need for structural material, and added >extra forward thrust from the earth beam on the back of the ship. (I don't >by the ship running on a tiny beam that just fits in the sail. The ship will >need to maneuver, and the transmitters couldn't hope to generate that much >accuracy.) Increased structural material, indeed, but that does not matter, because the heavier the retro-mirror the less the doppler shifts. I don't buy you saying that the beam may be much bigger than the mirror. If you throw away most of the energy anyway, just by using a mirror that is too small, than you could also use an engine that has a worthless effeciency. Furthermore, I don't see why the ship wants to maneuver so much. It always has to stay in the beam for most of the time. If indeed the accuracy of the transmitters is that worse, my advice is to no use the beaming idea. >- The energy retuning to ship will drop off like a rock as the distance >between ship and retro or drop mirror increases. Given that the mirror will >not be that smooth (it will probably be rippling) the beam will be diverging >badly after it reflects. How well do you think that a plasma will reflect? Probably my almost flat mirror would do a much better job. I really don't agree using a beam for about 10% or less. It should be at least 50% otherwise, other systems may be more effecient. ============================================================================== Timothy re: Kelly Subject : nanoAI >Easier? The ship would still need to carry something like its own weight in >matter anti-mater. A mass of thousands to millions of tons. Forward was >hoping optimistically we'd be able to routinely generate and store milligrams >to grams of antimatter. Once again, anti-matter is just energy. The only thing that is important is the efficiency. How well can we transfer energy to matter? My assumtion is that this efficiency should be about 50% in 2040. If this isn't reasonable, than indeed it is a bad choice. My guess is that Forward also has no idea of generating 10E18 Watts of power or a total amount of 1E26 Joules of energy! And this is approx. the energy and power needed for most designs. >True, but since no current A.I. system works very well, and no nano-tech >systems work at all, I'd have a very hard time expecting them to be developed >to that degree of reliability in 50 years. Its out there with the "we >discover warp drive possibilities". Sooner or later we'll do them, or >something like them; but they don't fit within LITs "no radical new tech" >parameters Have you seen any (well) working plasma-mirrors yet? I really think that nanoAI is not that exotic as you think. The AI systems of today are capable of learning to read out loud (but not to understand). One of the things that keeps them from doing more difficult tasks is the amount of "neurons" (currently about 1E8 or so). This amount depends both on fast and vast memories. There has just been designed a chip with a build in neural-network for all kinds of purposes. About nano-tech I know a bit less, but certainly there are significant breaktroughs. And nano-tech has the same potential as computers had. Once there is a beginning, growth will be exponentially. >One thing I was considering was what we can do. My Explorer design could >certainly be able to carry enough fusion fuel to decelerate from 1/10th C. > Marshal Savage mention something like a 20 to 1 fuel to ship mass ration to >do that. I'd like to check that, but for the moment will assume its true. I checked it and its even better. For acceleration and deceleration a ratio of 1:10 when the exhaust speed is about 0.088 c (Quite critical value) For 0.2c the ratio becomes 1:100 and for 0.3c it is about 1:1100 > Obviously trying to do that at 2/10ths C would take 20 squared (400) ship >masses of fuel. So thats out, but at even those speeds drag is a serious >factor. Savages book mentions that at near light speed the (one atom per >cubic centimeter) inter-stellar Medium could cause up to 37 milligrams of >drag pressure per square centimeter of frontal area. I'd like to work up the >numbers for various interstellar densities and ship speeds; but it seems >likely that some kind of magnetic or electrostatic, scoop or parachute could >give us a big amount of breaking force. 3E10 cm/s * 1 atom/cm^3 = 3E10 atoms/cm^2 3E10 atoms/cm^2 * 1.67E-27 kg/atom = 5E-17 kg/cm^2 As you can see that number of Savage is completely wrong. (I did this calculation a week ago also!) >If we stay with a .1 to .2 C top speed ship we might be able to get a >practical mission to some of the nearer stars. Not Tau C, but Alpha Centuri, >Barnard's, Rigil Kent (Rigel kent A is a G2 yellow Main star at 4.4 LY, B is >a K6 orange-main at 4.4). A .2 C ship could get there in a usable period of >time. A version of my Explorer Fusion design could get there and back. If >you have some reason of wanting to go there regularly. The first ship could >assemble automated fuel launchers in the target systems. That would allow >lighter ships to make the same run at higher speeds without carrying heavy >fuel loads. (Assuming they trusted the fuel launcher at the receiving system >to answer their launch command.) 4.4/0.2=22 years for a complete one way trip. Not better than we are currently planning for TC. >So I guess what we want to do there is a question that we'd need to resolve. > More specifically why we'ld feel we needed to do it then? If you willing to >wait another half century. You could expect to have relyable equipment based >on physics unknown to us now. (Matter conversion? Time space distortion? > Such things have been seriously proposed.) This was what I meant, and I haven't got a clue what the answer could be. But as you said this has nothing to do with the initial goal of SD. Timothy From popserver Sat Dec 16 18:03:12 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["16120" "Fri" "15" "December" "1995" "23:08:09" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "347" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail04.mail.aol.com (mail04.mail.aol.com [152.163.172.53]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id UAA21343 for ; Fri, 15 Dec 1995 20:09:19 -0800 (PST) Received: by mail04.mail.aol.com (8.6.12/8.6.12) id XAA24326; Fri, 15 Dec 1995 23:08:09 -0500 Message-ID: <951215230809_91593264@mail04.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl cc: Bogart1594@aol.com, David@interworld.com, lunar@sunsite.unc.edu Subject: Re: Engineering Newsletter Date: Fri, 15 Dec 1995 23:08:09 -0500 >> Timothy re: Kelly >> Subject : Plasma mirror >> >> >You still haven't dealt with the problems of a drop mirror. >> > - Given that the point of the exercise is that the mirror and ship will >> >accelerate apart until they are moving apart at nearly light speed. They >> >will be getting very far apart, and the "Retro-mirror" will need to aim to >> >track the decelerating ship. By having the ships flat reflector mirror the >> >size of the full power mirrors you eliminate the retro-mirror needs to focus, >> >but not to keep aiming at the retreating ship. >> >> "Very far" would be something like 2 ly: >> The mirror and the ship will be furthest apart when the Asimov has >> decelerated and is near TC. >> It takes approximately 8 years to decelerate the Asimov. The mirror never >> exceeds the speed of light and thus travels about 8 ly. It is released from >> the Asimov when 6 ly from TC. So after 8 years the Asimov has decelerated >> and is near TC. The mirror is then thus 2 ly further than TC and the Asimov. >> >> So the extra distance is not so much as you would think. But of course still >> the problem of aiming is there. I've no solution other than some >> gyro-system. But what I don't understand is what is the difference between >> aiming the beam that comes from Earth and the beam that comes from the >> retro-mirror? The only thing the retro-mirror has to do is not turn, so it >> does not have to aim but just not have to turn. >> Do you know what the difference is between aiming the beam from Earth and >> aiming from the retro-mirror? Yes, the beam from earth can be maintained by a massive infrastructure of people carefully tuning it to keep it in the track to T.C. They also can make up for accuracy problems by making a bigger beam. Transmitting a hundred or a thousand times as much power as needed to compensate for all the waste that misses the ship. Thats not very efficient (but thats not a problem), and will cost a lot more (which might be a problem); but it could still work. (Actually you would need to do that anyway in order to give the ship some room to maneuver around in the beam.) The retro-sail on the other hand is a weak flimsy structure of huge dimensions, which has to keep a pinpoint aim of nearly all its reflected energy at a distance of light years. A neat trick given its basically a huge unsupported sheet of foil being blown along by the beam. Oh, and it would have to keep a pinpoint aim on a moving object up to two light years away. So it would be 2 years out of date in its understanding of where the ship was, and was going. And no you can't just not turn. First, given the load on it from the beam, its certain it will being twisted by beam asysmetries. Secound the ship can't be in direct line between the mirror and the beam, so their will be a changing angular offset. >> > In trade you've added increased need for structural material, and added >> >extra forward thrust from the earth beam on the back of the ship. (I don't >> >by the ship running on a tiny beam that just fits in the sail. The ship will >> >need to maneuver, and the transmitters couldn't hope to generate that much >> >accuracy.) >> >> Increased structural material, indeed, but that does not matter, because the >> heavier the retro-mirror the less the Doppler shifts. Also the more power you need to drive it and the ship up to speed, and more power needs for its maneuvering systems to turn it to keep aimed at the ship. Besides you couldn't possibly add enough mass to a structure hundreds to thousands of kilometers across to keep it optically flat! >> I don't buy you saying that the beam may be much bigger than the mirror. If >> you throw away most of the energy anyway, just by using a mirror that is too >> small, than you could also use an engine that has a worthless efficiency. The beam must be much bigger then the sail, and wasting energy isn't a critical problem. The purpose of the beam is to drive the ship. As long as enough of the beam gets to the ship to do that, the system can work. (I.E. the it can get the ship where it wants to go.) Efficiency is a cost concern, but would not effect the success of the project. After all you don't have to move the transmitters. The ships engines however have to be pretty efficient in order to get the job done (and not melt the ship in the process). We're nowhere near being able to design a starship that can "affordably" get back and forth to Tau Ceti. >> Furthermore, I don't see why the ship wants to maneuver so much. It always >> has to stay in the beam for most of the time. >> If indeed the accuracy of the transmitters is that worse, my advice is to no >> use the beaming idea. I expect it will need to maneuver around any interstellar rocks or other such junk. (Hitting a 4 kilometer comet at relativistic speeds is hard on the hull!!) One advantage of the beamed concept is that the unreflected energy acts as a radar searchlight to show whats ahead of the ship. >> >- The energy returning to the ship will drop off like a rock as the distance >> >between ship and retro or drop mirror increases. Given that the mirror will >> >not be that smooth (it will probably be rippling) the beam will be diverging >> >badly after it reflects. >> >> How well do you think that a plasma will reflect? Probably my almost flat >> mirror would do a much better job. The plasma reflector will be right next to the ship (surrounded by it actually). So couldn't possibly miss the ship, and doesn't need to keep a tightly aimed beam. The retro-mirror on the other hand will be up to 2 light years from the ship, and need to reflect a perfectly beam that converges inward toward a smaller drive mirror on the ship. The later is a much harder problem. >> I really don't agree using a beam for about 10% or less. It should be at >> least 50% otherwise, other systems may be more efficient. Do you mean you don't want to use a beam system thats that inefficient? Efficiency in catching the beam is a luxury we can worry about later. Right now we're just trying to devise a system that could possibly get us there at all! The choice isn't going wastefully vs going efficiency, but going wastefully or not going at all! ============================================================================== >> >> Timothy re: Kelly >> Subject : nanoAI >> >> >Easier? The ship would still need to carry something like its own weight in >> >matter anti-mater. A mass of thousands to millions of tons. Forward was >> >hoping optimistically we'd be able to routinely generate and store milligrams >> >to grams of antimatter. >> >> Once again, anti-matter is just energy. The only thing that is important is >> the efficiency. How well can we transfer energy to matter? My assumption is >> that this efficiency should be about 50% in 2040. If this isn't reasonable, >> than indeed it is a bad choice. >> My guess is that Forward also has no idea of generating 10E18 Watts of power >> or a total amount of 1E26 Joules of energy! >> And this is approx. the energy and power needed for most designs. I have no idea how you plan to convert energy directly to anti-matter. Certainly thats not how we make it now. Even if we could generate the anti matter, how would you store and move amounts on that scale safely? And of course how do you refuel for the return trip? Your probably right about the E18+ power being a 'show stopper' thou. I can't think of any reasonable scenario that would have us able to put that kind of power on line, in space, in about 50 years. >> >True, but since no current A.I. system works very well, and no nano-tech >> >systems work at all, I'd have a very hard time expecting them to be developed >> >to that degree of reliability in 50 years. Its out there with the "we >> >discover warp drive possibilities". Sooner or later we'll do them, or >> >something like them; but they don't fit within LITs "no radical new tech" >> >parameters >> >> Have you seen any (well) working plasma-mirrors yet? I really think >> that nanoAI is not that exotic as you think. >> The AI systems of today are capable of learning to read out loud (but not to >> understand). One of the things that keeps them from doing more difficult >> tasks is the amount of "neurons" (currently about 1E8 or so). This amount >> depends both on fast and vast memories. There has just been designed a chip >> with a build in neural-network for all kinds of purposes. >> About nano-tech I know a bit less, but certainly there are significant >> breakthroughs. And nano-tech has the same potential as computers had. Once >> there is a beginning, growth will be exponentially. Your definitely more optimistic about nano and A.I. than I. We after all can and do reflect radio and microwave off ionized gas all the time. We have no Nano systems, and are making painfully slow progress in A.I. (A.I. first learned to read aloud over ten years ago.) So I do think they are unlikely to be mature enough in 50 years to help us much. Actually, even if they did work, they wouldn't solve any critical problems for us. Just improve effecency and affordability. >> >One thing I was considering was what we can do. My Explorer design could >> >certainly be able to carry enough fusion fuel to decelerate from 1/10th C. >> > Marshal Savage mention something like a 20 to 1 fuel to ship mass ration to >> >do that. I'd like to check that, but for the moment will assume its true. >> >> I checked it and its even better. For acceleration and deceleration a ratio >> of 1:10 when the exhaust speed is about 0.088 c (Quite critical value) >> >> For 0.2c the ratio becomes 1:100 and for 0.3c it is about 1:1100 Hum... I just ran some numbers through the LIT Delta V program using the specific impulse of Bussards Fusion engines. I got about the same numbers at ..3c but I though I got slightly better numbers at .2c. But I don't have the numbers with me. Then again, I'm not even sure the LIT program nows to add the need to accelerate the fuel mass with the ship (I certainly hope it does, I'll have to test it.) >> > Obviously trying to do that at 2/10ths C would take 20 squared (400) ship >> >masses of fuel. So thats out, but at even those speeds drag is a serious >> >factor. Savages book mentions that at near light speed the (one atom per >> >cubic centimeter) inter-stellar Medium could cause up to 37 milligrams of >> >drag pressure per square centimeter of frontal area. I'd like to work up the >> >numbers for various interstellar densities and ship speeds; but it seems >> >likely that some kind of magnetic or electrostatic, scoop or parachute could >> >give us a big amount of breaking force. >> >> 3E10 cm/s * 1 atom/cm^3 = 3E10 atoms/cm^2 >> 3E10 atoms/cm^2 * 1.67E-27 kg/atom = 5E-17 kg/cm^2 >> >> As you can see that number of Savage is completely wrong. (I did this >> calculation a week ago also!) Yeah, I dug up some numbers from my old web page (see above) that showed he was off the wall too. (Well at relativistic speeds time dilation might help his numbers) Looks like no magnetic drag chutes. >> >If we stay with a .1 to .2 C top speed ship we might be able to get a >> >practical mission to some of the nearer stars. Not Tau C, but Alpha Centauri, >> >Barnard's, Rigil Kent (Rigel kent A is a G2 yellow Main star at 4.4 LY, B is >> >a K6 orange-main at 4.4). A .2 C ship could get there in a usable period of >> >time. A version of my Explorer Fusion design could get there and back. If >> >you have some reason of wanting to go there regularly. The first ship could >> >assemble automated fuel launchers in the target systems. That would allow >> >lighter ships to make the same run at higher speeds without carrying heavy >> >fuel loads. (Assuming they trusted the fuel launcher at the receiving system >> >to answer their launch command.) >> >> 4.4/0.2=22 years for a complete one way trip. Not better than we are >> currently planning for TC. But, it would require far simpler systems, and a fraction of the power. A comparatively simple fusion powered ship with fuel launchers in sol could make a round trip. If it builds a big fuel launcher in the target system it could even cut the return trip time down. Like I said above, I ran some numbers off using the delta-v program on the LIT site, and got a 60 to 1 fuel to ship mass ration for a .2c Delta v, using the Bussard fusion drive motors. Thats not an impossible number (bad, but not impossible). So I think such a ship could be built by 2050. So we could get to the nearer stars. At .2c we could get to the 4.5 to 5ish ly stars in 22-25 years. Which should be quick enough to be do able (thou its pushing it!), thou the crew will probably die durring the 25 year return flight. On the return flight the ship would load up with enough fuel to boost it back up to speed. It couldn't possibly carry enough fuel to accelerate, and decelerate! So it will have to use fuel launched by the Sol fuel launchers to power its deceleration boost. (Better home the folks back home still like you! ;) ) But then again, if we bring enough gear to build a fuel launcher at the target star system. The ship could boost for home with little or no fuel on board. Its speed wouldn't be limited to the maximum speed it can get out of the stored fuel its carring, or that it can carry the deceleration fuel to stop from. Accelerating with near empty fuel tanks the ship will weight a tiny fraction of the max weight its engines and structure were designed for. The crew could keep the extra for redundancy (the ship will be getting old by then), or they could strip some or all of the systems off to lighten the ship even further. Allowing the crew to boost at higher G's in the acceleration track, order to get to higher speeds. Remember, the limitation on accelerating in a pre-launched fuel stream. Is how far out you can get before the fuel gets so spread out that you can't scoop up enough fuel to run the engines. I.E. how accuratly can you launcher put the fuel? A striped down ship could not only accelerate faster, getting to higher speeds within a given distence from the fuel launcher. It could also get by on less fuel, allowing it to still keep up thrust farther out from the fuel launcher then its heavyer brother. If the folks back home really like you. They will have upgraded their fuel launcher in your absence. Allowing you to get a usable fuel density at far farther out from Sol. >> >So I guess what we want to do there is a question that we'd need to resolve. >> > More specifically why we'd feel we needed to do it then? If you willing to >> >wait another half century. You could expect to have reliable equipment based >> >on physics unknown to us now. (Matter conversion? Time space distortion? >> > Such things have been seriously proposed.) >> >> This was what I meant, and I haven't got a clue what the answer could be. >> But as you said this has nothing to do with the initial goal of SD. Yeah, but it seems to be an issue we need to resolve. As is, a .2 C ship with the ability to go faster with fuel launchers at both ends, seems reasonable by 2050. A near light speed ship seems out of the question. The microwave sail idea requires completely absurd amounts of power, and we can't seem to find a practical way to stop the ship. So until we change the physics we have to work with (or learn a much better way to manufacture and store anti-matter) we are limited to slower, shorter range fights. But flights that would be technically (and financially) far less chalenging. Does anyone disagree? Kelly P.S. Where is David? I keep geting undeliverable mail mesages when I ship to his office. Has anyone heard from him lately? P.P.S. Opps, I forgot to look up the thrust to weight ratio of the Bussard plasma engines. If their too low, the ship wouldn't be able to carry enough fuel. From popserver Sat Dec 16 20:38:55 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["12175" "Sat" "16" "December" "1995" "21:36:56" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "243" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id MAA16981 for ; Sat, 16 Dec 1995 12:36:03 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA21246 (5.67b/IDA-1.5 for ); Sat, 16 Dec 1995 21:36:50 +0100 Message-Id: <199512162036.AA21246@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 16 Dec 1995 21:36:56 +0100 Timothy re: Kelly Subject : Plasma mirror >Yes, the beam from earth can be maintained by a massive infrastructure of >people carefully tuning it to keep it in the track to T.C. They also can >make up for accuracy problems by making a bigger beam. Transmitting a >hundred or a thousand times as much power as needed to compensate for all the >waste that misses the ship. Thats not very efficient (but thats not a >problem), and will cost a lot more (which might be a problem); but it could >still work. (Actually you would need to do that anyway in order to give the >ship some room to maneuver around in the beam.) > >The retro-sail on the other hand is a weak flimsy structure of huge >dimensions, which has to keep a pinpoint aim of nearly all its reflected >energy at a distance of light years. A neat trick given its basically a huge >unsupported sheet of foil being blown along by the beam. Oh, and it would >have to keep a pinpoint aim on a moving object up to two light years away. > So it would be 2 years out of date in its understanding of where the ship >was, and was going. OK, I see the difference. But what I want to make clear is that it does not have to know where the ship is. (see next comment) >And no you can't just not turn. First, given the load on it from the beam, >its certain it will being twisted by beam asysmetries. Secound the ship >can't be in direct line between the mirror and the beam, so their will be a >changing angular offset. What I meant with no turning, was that it just had to reflect the beam STRAIGHT back. To do that is has a very precise orientation: the incoming beam. The mirror does not have to track a moving object, that is the task of the Earth beaming station. If Earth beams it to the Asimov, then it also aims to the mirror. because the Asimov and the retro-mirror are always lined up. >Also the more power you need to drive it and the ship up to speed, and more >power needs for its maneuvering systems to turn it to keep aimed at the ship. > Besides you couldn't possibly add enough mass to a structure hundreds to >thousands of kilometers across to keep it optically flat! Both are true, but since you are talking about losses of 99% or 99.9% (due to beam that is bigger than the mirror) I guess that energy to maneuver is just a minor extra. Also the heavier the mirror, the less it is turned by the beam, so it takes less to turn it back. (So the total energy stays about the same) >The beam must be much bigger then the sail, and wasting energy isn't a >critical problem. The purpose of the beam is to drive the ship. As long as >enough of the beam gets to the ship to do that, the system can work. (I.E. >the it can get the ship where it wants to go.) Efficiency is a cost concern, >but would not effect the success of the project. After all you don't have to >move the transmitters. The ships engines however have to be pretty efficient >in order to get the job done (and not melt the ship in the process). We're >nowhere near being able to design a starship that can "affordably" get back >and forth to Tau Ceti. Efficiency is not only a cost concern, if we had 100 to 1000 times more energy available, then certain things would be a lot easier. >I expect it will need to maneuver around any interstellar rocks or other such >junk. (Hitting a 4 kilometer comet at relativistic speeds is hard on the >hull!!) One advantage of the beamed concept is that the unreflected energy >acts as a radar searchlight to show whats ahead of the ship. I think that the beam from Earth has completely ionized and blown away these rocks before the Asimov gets into sight. Also there won't be that many big rocks in interstellar space. (If they were, they would certainly make a good braking force) >The plasma reflector will be right next to the ship (surrounded by it >actually). So couldn't possibly miss the ship, and doesn't need to keep a >tightly aimed beam. The retro-mirror on the other hand will be up to 2 light >years from the ship, and need to reflect a perfectly beam that converges >inward toward a smaller drive mirror on the ship. The later is a much harder >problem. Both the retro-mirror and the mirror on the Asimov are about the same size! You say the plasma surrounds the ship, I thought they were at the TC side of the ship. Does design looks like this: ) ------------) /) (--------| Plasma (--------| Plasma \) ------------) ) ( are the small mirror at the Earth side of the Asimov ) are the big mirror at TC side of the Asimov -- / \ Light rays As soon as the photons hit the plasma how are they reflected? >Do you mean you don't want to use a beam system thats that inefficient? >Efficiency in catching the beam is a luxury we can worry about later. Indeed, that's what I'm saying. If a system is only 10% or even 0.1% efficient, then for example a fusion system that uses a 1:1000 ship:fuel ratio as well. >Right >now we're just trying to devise a system that could possibly get us there at >all! The choice isn't going wastefully vs going efficiency, but going >wastefully or not going at all! I do not agree, as I said before, the anti-matter engine WILL work. Only you do think that it is very difficult to make anti-matter if you have the energy available. I, on the other hand don't see a reason why this should be so extremely difficult in 50 years. (And if efficiency isn't that important this will certainly be an option) My calculations tell me that to reach 0.9c one needs approximately: 1 spoon of spacevessel 1 spoon of anti-matter 4 spoons of normal matter ============================================================================== Timothy re: Kelly Subject : nanoAI >I have no idea how you plan to convert energy directly to anti-matter. > Certainly thats not how we make it now. Even if we could generate the anti >matter, how would you store and move amounts on that scale safely? And of >course how do you refuel for the return trip? Today we use the brute force method of collision. The particles that are created during that collision are not used and the energy of them is thrown away after detecting them. (nothing gets much overheated since we are talking about only a few particles) The biggest losses are due to the cooling of the (super-conducting) magnets. If such a collider is build in space or if room-temp. supercoliders are discovered these big losses may come down. Also the collision should be made more efficient in the way that some particles like neutrons and protons are created more often than other particles. I think this could be done by using the exact right collision energies. Another possibility could be to create an energy field (eg. a box with a lot of photons) Then more (virtual) particles will form that may be extracted. This method is never used because it is not so easy to create such high energy fields, but I think it should work. How to store the anti-matter? Just like normal matter, create anti-atoms and anti-solids. Finally charge it and suspend it in electro/magnetic bottles. OK, it sounds easy, but it seems to be possible. How to refuel? First of all, I'm not so certain that it will return. You would be 65 when you're back on Earth while all you worked and lived for is on TC. Just to come back and play the hero doesn't seem that much fun. But if you really want, than you have to build a refueling station at TC. Too difficult? All methods need to build some kind of beaming or fuel station at TC and all are probably difficult to realize. >Your probably right about the E18+ power being a 'show stopper' thou. I can't >think of any reasonable scenario that would have us able to put that kind of >power on line, in space, in about 50 years. I think that we have to assume that this minimum is possible, otherwise no system is possible unless we "invent" anti-gravity, or if we use a ship that has much less mass (which is almost impossible). So it would be better if one the rules of the SD "discussion" was that a minimum (unknown?) power source of 1E18 watt is available in 2040. >Your definitely more optimistic about nano and A.I. than I. We after all can >and do reflect radio and microwave off ionized gas all the time. We have no >Nano systems, and are making painfully slow progress in A.I. (A.I. first >learned to read aloud over ten years ago.) So I do think they are unlikely >to be mature enough in 50 years to help us much. We indeed do reflect radio-waves, but we do that always at a non-perpendicular angle. I'm not sure but, I think it works worse for right angles. >Actually, even if they did work, they wouldn't solve any critical problems >for us. Just improve effecency and affordability. Increasing efficiency or affordability make any design more probable and feasable. If for example the space shuttle had AI and nanotech. it would probably much more saver, reliable and cheaper. If one makes such a big ship, a lot of things may go wrong and endanger the trip. The more complex the ship, the more probable that the trip isn't completed. NanoAI will decrease that probability significantly. >Hum... I just ran some numbers through the LIT Delta V program using the >specific impulse of Bussards Fusion engines. I got about the same numbers at >.3c but I though I got slightly better numbers at .2c. But I don't have the >numbers with me. Then again, I'm not even sure the LIT program nows to add >the need to accelerate the fuel mass with the ship (I certainly hope it does, >I'll have to test it.) I've made a derivation and a Pascal program that can do such calculations. It's on the WWW at URL: http://www.cpedu.rug.nl/~N0642983/calc.txt >Like I said above, I ran some numbers off using the delta-v program on the >LIT site, and got a 60 to 1 fuel to ship mass ration for a .2c Delta v, >using the Bussard fusion drive motors. Thats not an impossible number (bad, >but not impossible). So I think such a ship could be built by 2050. So we >could get to the nearer stars. At .2c we could get to the 4.5 to 5ish ly >stars in 22-25 years. Which should be quick enough to be do able (thou its >pushing it!), thou the crew will probably die durring the 25 year return >flight. My ratios where for acceleration AND deceleration together. Nearer goals would indeed make a better chance of succeeding, also it would be a cheaper way to "test" interstellar space-trips. The disadvantage is of course that the number of stars is much smaller and so are the chances of finding lifeforms or habitable planets. >Remember, the limitation on accelerating in a pre-launched fuel stream. Is >how far out you can get before the fuel gets so spread out that you can't >scoop up enough fuel to run the engines. I.E. how accuratly can you launcher >put the fuel? A striped down ship could not only accelerate faster, getting >to higher speeds within a given distence from the fuel launcher. It could >also get by on less fuel, allowing it to still keep up thrust farther out >from the fuel launcher then its heavyer brother. If the folks back home >really like you. They will have upgraded their fuel launcher in your >absence. Allowing you to get a usable fuel density at far farther out from >Sol. I've done some calculations, these show there is not that much profit (in energy) when one compares prelaunching with take-all-with-you (from now on TAWY). >So until we change the physics we have to work with (or learn a much better >way to manufacture and store anti-matter) we are limited to slower, shorter >range fights. But flights that would be technically (and financially) far >less chalenging. Does anyone disagree? Indeed, even with anti-matter there will be a limit, it will be something like 100 ly. But what a world would we create: It isn't possible to ask something and receive an answer within a lifetime. Even 4 ly is a big barrier. What happens if one creates a world that far away from Earth. It is in fact a isolated world. There won't be interactive communication. All information streams will be one way (from boths sides). Timothy From popserver Sun Dec 17 18:07:23 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2417" "Sun" "17" "December" "1995" "10:07:58" "-0500" "David Levine" "David@interworld.com" nil "48" "RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id HAA07789 for ; Sun, 17 Dec 1995 07:05:03 -0800 (PST) Received: by www with Microsoft Mail id <01BACC67.8D248AB0@www>; Sun, 17 Dec 1995 10:08:02 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BACC67.8D3CF4B0" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: Engineering Newsletter Date: Sun, 17 Dec 1995 10:07:58 -0500 ------ =_NextPart_000_01BACC67.8D3CF4B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Um, gang, sorry about the confusion. Our T1 has been down for over a week. Ugh. Anyway, I'm back on the air. It's going to take me a while to get back to speed, but at least mail to me won't bounce anymore. Thanks for understanding. David -- David Levine - Senior Applications Programmer - InterWorld http://www.interworld.com/staff/david/ "He tried to kill me with a forklift..." -------------------------------------------------------------------------- ------ =_NextPart_000_01BACC67.8D3CF4B0 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IgMPAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAARAAoA BwA6AAAAOgEBCYABACEAAABERDk1REQxQUY3MzdDRjExQUMwNzAwODA1RjE0QTJGMAA+BwEggAMA DgAAAMsHDAARAAoACAACAAAAAwEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAGwAAAFJFOiBFbmdpbmVlcmluZyBOZXdzbGV0dGVyAKkJAQ2ABAACAAAAAgACAAEDkAYA9AMA ABIAAAALACMAAAAAAAsAKQAAAAAAAwAmAAAAAAADADYAAAAAAB4AcAABAAAAFwAAAEVuZ2luZWVy aW5nIE5ld3NsZXR0ZXIAAAIBcQABAAAAGwAAAAG6y/KFp1DRaQY34RHPrAYAgF8UovAAJ47j8gAD AAYQw5K5cgMABxB4AQAAHgAIEAEAAABlAAAAVU0sR0FORyxTT1JSWUFCT1VUVEhFQ09ORlVTSU9O T1VSVDFIQVNCRUVORE9XTkZPUk9WRVJBV0VFS1VHSEFOWVdBWSxJTUJBQ0tPTlRIRUFJUklUU0dP SU5HVE9UQUtFTUVBVwAAAAADABAQAAAAAAMAERAAAAAAAgEJEAEAAABQAgAATAIAAMgDAABMWkZ1 tjzfav8ACgEPAhUCqAXrAoMAUALyCQIAY2gKwHNldDI3BgAGwwKDMgPFAgBwckJxEeJzdGVtAoMz twLkBxMCgzQSzBTINREMtjEPzwIANgPGFMV9CoCLCM8J2Tsa+TEyOAojxxzRHBoKFDI1NQKACoGD DbELYG5nMTAzFFAXCwoUUQvyYxKgIFVtWCwgZx9hIXBzBbByHHkgAaAIYAVAdGhlYiAFoG5mdQCQ AiAuyCAgTwhwIFQX4BGAhQQgYgnhIGRvdwOgZQIQcgqFb3YEkCJAIIp3CeBrI4FVZ2gjgUBBbnl3 YXkhcEnsJ20kUADQayWQA6AiskULcHIjgUl0JwQgZypvC4BnIqBvIqBha+5lCoUHgCXiaAMQItAp cU5nEcAnlClxc3AJ4GT1IXBiIoFhBUAq0CQwBUCvAMADESlxKlF3AiAnK1F5CGBuYynWAHAGwAWw ZZYuCoUKhVQRgG5rBCC9JQEgLmAEgRPAAHBkKTFBL41EYXZpZAqLbLhpMzYN8CA8E1BvE9DeYwVA Co8LkRViMRkgIRAnAFAAoDVGLS0yeiBM6mUzAG4i0C0GUQMABbHkQXALUGljLKAjUQQg5lADYAnA YW0HgAXAObBWSQIwBJBXBbBsMyZoQQJAcDovL3c9YC4vC4A8AS3gPFEuBaBtL1MxcQ3QL2Qy8i81 xSLeSCrhCIE5IClxawMQAyDdLbJpIrAl4SUBazQAAYD6LkIAIjXFOFBCz0PfRO/fRf9GQgtGFvE3 MDc1PhohAgBJcEAAOQCw82Rzkcy6AQIBRwABAAAANAAAAGM9VVM7YT0gO3A9SW50ZXJXb3JsZDts PVByaXZhdGUgTURCLTk1MTIxNzE1MDc1OVotMQBAAAcwEHVjc5HMugFAAAgwoJ4UdpHMugEeAD0A AQAAAAUAAABSRTogAAAAAAIBFDQBAAAAEAAAAFSUocApfxAbpYcIACsqJRcXFg== ------ =_NextPart_000_01BACC67.8D3CF4B0-- From popserver Mon Dec 18 18:02:37 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["11190" "Sun" "17" "December" "1995" "22:45:54" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "267" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id TAA05766 for ; Sun, 17 Dec 1995 19:46:32 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id WAA09592; Sun, 17 Dec 1995 22:45:54 -0500 Message-ID: <951217224552_57060897@emout06.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sun, 17 Dec 1995 22:45:54 -0500 > > Timothy re: Kelly > Subject : Plasma mirror > What I meant with no turning, was that it just had to reflect the beam > STRAIGHT back. To do that is has a very precise orientation: the incoming > beam. The mirror does not have to track a moving object, that is the task of > the Earth beaming station. If Earth beams it to the Asimov, then it also > aims to the mirror. because the Asimov and the retro-mirror are always lined up. That wouldn't work, but eiather way. Straight back is still a direction to aim at, and it couldn't do it. --- snip --- > >The beam must be much bigger then the sail, and wasting energy isn't a > >critical problem. The purpose of the beam is to drive the ship. As long as > >enough of the beam gets to the ship to do that, the system can work. (I.E. > >the it can get the ship where it wants to go.) Efficiency is a cost concern, > >but would not effect the success of the project. After all you don't have to > >move the transmitters. The ships engines however have to be pretty efficient > >in order to get the job done (and not melt the ship in the process). We're > >nowhere near being able to design a starship that can "affordably" get back > >and forth to Tau Ceti. > > Efficiency is not only a cost concern, if we had 100 to 1000 times more > energy available, then certain things would be a lot easier. > > >I expect it will need to maneuver around any interstellar rocks or other such > >junk. (Hitting a 4 kilometer comet at relativistic speeds is hard on the > >hull!!) One advantage of the beamed concept is that the unreflected energy > >acts as a radar searchlight to show whats ahead of the ship. > > I think that the beam from Earth has completely ionized and blown away these > rocks before the Asimov gets into sight. Also there won't be that many big > rocks in interstellar space. (If they were, they would certainly make a good > braking force) We have no real idea whats in interstellar space, but is fair to expect a few comets, asteroids ect; and I don't think we can plan on everything in our way getting neatly blown out of the way. > >The plasma reflector will be right next to the ship (surrounded by it > >actually). So couldn't possibly miss the ship, and doesn't need to keep a > >tightly aimed beam. The retro-mirror on the other hand will be up to 2 light > >years from the ship, and need to reflect a perfectly beam that converges > >inward toward a smaller drive mirror on the ship. The later is a much harder > >problem. > > Both the retro-mirror and the mirror on the Asimov are about the same size! NO! A retro reflecter mirror wil not work unless the retro-mirror is much bigger. -If its the same size and the retro mirror is straight in frount of the ship. It will be in the shaddow of the ships drag mirror. So it won't 'see' any of the beam to reflect. - Even if its not in the line of sight. Being the same size as the drag mirror on the ship. It can't reflect anymore energy back to the drag mirror, than the mirror gets directly from earth. So It wouldn't be able to decelerate the ship. So it will have to be larger and focus the beam backward to a smaller beam. > > You say the plasma surrounds the ship, I thought they were at the TC side of > the ship. Does design looks like this: > > ) > -------------) > //) > (--------| Plasma > (--------| Plasma > \\) > ------------) > ) > > ( are the small mirror at the Earth side of the Asimov > ) are the big mirror at TC side of the Asimov > -- / \ Light rays Pretty much it. Imagine the ship as a hollow pipe with a plasma in the inside of the pipe and in frount of it. (The ship surrounds the plasma, not the other way round.) The microwaves are reflected back and inward by the forward main ring sial, toward the rear ring sail (drag sail) which reflects it forward inside the open area of the ship toward the plasma. It heats and is reflected off the plasma backward. > As soon as the photons hit the plasma how are they reflected? > > >Do you mean you don't want to use a beam system thats that inefficient? > >Efficiency in catching the beam is a luxury we can worry about later. > > Indeed, that's what I'm saying. If a system is only 10% or even 0.1% > efficient, then for example a fusion system that uses a 1:1000 ship:fuel > ratio as well. As well what? Efficency is not nessisary for a system to be usable, but a ship that needs to carry a thousand times its weight in fuel simply can't be built. > >Right > >now we're just trying to devise a system that could possibly get us there at > >all! The choice isn't going wastefully vs going efficiency, but going > >wastefully or not going at all! > > I do not agree, as I said before, the anti-matter engine WILL work. Only you > do think that it is very difficult to make anti-matter if you have the > energy available. I, on the other hand don't see a reason why this should be > so extremely difficult in 50 years. > (And if efficiency isn't that important this will certainly be an option) You've never suggested how you think such amounts of anti-matter could be made. Or how we could build such engines. Or store such amounts of antimater. 2050 is to close for us to overcome all those problems on that scale. > Another possibility could be to create an energy field (eg. a box with a lot > of photons) Then more (virtual) particles will form that may be extracted. > This method is never used because it is not so easy to create such high > energy fields, but I think it should work. Why? We've never tried any of it. > How to store the anti-matter? Just like normal matter, create anti-atoms and > anti-solids. Finally charge it and suspend it in electro/magnetic bottles. > OK, it sounds easy, but it seems to be possible. In theory, but its a big jump from theoretically possible to usable. > How to refuel? First of all, I'm not so certain that it will return. You > would be 65 when you're back on Earth while all you worked and lived for is > on TC. Just to come back and play the hero doesn't seem that much fun. > But if you really want, than you have to build a refueling station at TC. > Too difficult? All methods need to build some kind of beaming or fuel > station at TC and all are probably difficult to realize. We went around on that question a lot a few months ago. Yes you have to bring the crews back. No one would fund a suicide run without a desparte need, and we don't have one. > >Your probably right about the E18+ power being a 'show stopper' thou. I can't > >think of any reasonable scenario that would have us able to put that kind of > >power on line, in space, in about 50 years. > > I think that we have to assume that this minimum is possible, otherwise no > system is possible unless we "invent" anti-gravity, or if we use a ship that > has much less mass (which is almost impossible). > So it would be better if one the rules of the SD "discussion" was that a > minimum (unknown?) power source of 1E18 watt is available in 2040. Or limit the discussion to systems and power levels that seem likely. > >Your definitely more optimistic about nano and A.I. than I. We after all can > >and do reflect radio and microwave off ionized gas all the time. We have no > >Nano systems, and are making painfully slow progress in A.I. (A.I. first > >learned to read aloud over ten years ago.) So I do think they are unlikely > >to be mature enough in 50 years to help us much. > > We indeed do reflect radio-waves, but we do that always at a > non-perpendicular angle. I'm not sure but, I think it works worse for right > angles. > > >Actually, even if they did work, they wouldn't solve any critical problems > >for us. Just improve effecency and affordability. > > Increasing efficiency or affordability make any design more probable and > feasable. If for example the space shuttle had AI and nanotech. it would > probably much more saver, reliable and cheaper. True, but since we havn't figured out a near lightspeed ship thats more than marginaly plausible, trying to cut costs on it doesn't mater. All that would do would be to make a nonfunctional system cheaper. > If one makes such a big ship, a lot of things may go wrong and endanger the > trip. The more complex the ship, the more probable that the trip isn't > completed. NanoAI will decrease that probability significantly. But of course, Nano are about the most complex and unrepairable systems we've even theorized making. > >Like I said above, I ran some numbers off using the delta-v program on the > >LIT site, and got a 60 to 1 fuel to ship mass ration for a .2c Delta v, > >using the Bussard fusion drive motors. Thats not an impossible number (bad, > >but not impossible). So I think such a ship could be built by 2050. So we > >could get to the nearer stars. At .2c we could get to the 4.5 to 5ish ly > >stars in 22-25 years. Which should be quick enough to be do able (thou its > >pushing it!), thou the crew will probably die durring the 25 year return > >flight. > > My ratios where for acceleration AND deceleration together. > > Nearer goals would indeed make a better chance of succeeding, also it would > be a cheaper way to "test" interstellar space-trips. > The disadvantage is of course that the number of stars is much smaller and > so are the chances of finding lifeforms or habitable planets. I'm suspicious of your fuel numbers. They seem too favorable. The odds of finding lifeforms and planets are how to judge. Certainly we're only taking about a handful of stars within search range. But it seems likely all of them could have planets, and we have no idea how picky life is about where it can form. In Sol, earths a yes, Mars is a maybe (please send unbroken lab gear) Venus I'd bet strongly against. As for the rest and their moons... ?? One thing we can be sure of, none of the planets out there will be habitable. Earth wouldn't be habitable to us if we hadn't evolved here. In any event a handfull of starsystems should keep us busy for a couple decades. Obviously past 2100 all the systems were discussing will seem archaic, and our physics quite naive. > >Remember, the limitation on accelerating in a pre-launched fuel stream. Is > >how far out you can get before the fuel gets so spread out that you can't > >scoop up enough fuel to run the engines. I.E. how accuratly can you launcher > >put the fuel? A striped down ship could not only accelerate faster, getting > >to higher speeds within a given distence from the fuel launcher. It could > >also get by on less fuel, allowing it to still keep up thrust farther out > >from the fuel launcher then its heavyer brother. If the folks back home > >really like you. They will have upgraded their fuel launcher in your > >absence. Allowing you to get a usable fuel density at far farther out from > >Sol. > > I've done some calculations, these show there is not that much profit (in > energy) when one compares prelaunching with take-all-with-you (from now on > TAWY). So? It would make a critical difference in the fuel mass ratio of the ship. Kelly From popserver Tue Dec 19 23:13:17 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8619" "Tue" "19" "December" "1995" "23:51:31" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "192" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id OAA07773 for ; Tue, 19 Dec 1995 14:51:11 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA05561 (5.67b/IDA-1.5 for ); Tue, 19 Dec 1995 23:51:11 +0100 Message-Id: <199512192251.AA05561@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 19 Dec 1995 23:51:31 +0100 Timothy re: Kelly Subject : Plasma mirror >>What I meant with no turning, was that it just had to reflect the beam >>STRAIGHT back. To do that is has a very precise orientation: the >>incoming beam. The mirror does not have to track a moving object, that >>is the task of the Earth beaming station. If Earth beams it to the >>Asimov, then it also aims to the mirror. because the Asimov and the >>retro-mirror are always lined up. > >That wouldn't work, but eiather way. Straight back is still a direction >to aim at, and it couldn't do it. Is it really that hard to keep the mirror straight? And still, if the beam deviates, the Asimov can still follow it (too a certain amount) by redirecting its own mirror. Doesn't this problem arise also on the Asimov itself, it too uses a big mirror to accelerate, if its mirror is a bit offside, it is out of the beam in seconds. If you move 1E8 metres in one second, only minute angles are needed to be off the "road" 1E4 metres or so. >We have no real idea whats in interstellar space, but is fair to expect a >few comets, asteroids ect; and I don't think we can plan on everything in >our way getting neatly blown out of the way. If there are indeed so many rocks that we have to worry, then we certainly should make use of them. How big do you think the chances are that any of these lumps comes even near the Asimov? >NO! A retro reflecter mirror wil not work unless the retro-mirror is much >bigger. >-If its the same size and the retro mirror is straight in frount of the > ship. > It will be in the shaddow of the ships drag mirror. So it won't 'see' > any of the beam to reflect. >-Even if its not in the line of sight. Being the same size as the drag > mirror on the ship. It can't reflect anymore energy back to the drag > mirror, > than the mirror gets directly from earth. So It wouldn't be able to > decelerate the ship. These two remarks mean that you haven't understood how I planned to make that retro-mirror! It was constructed of two mirrors at a right angle to each other... (See previous letters) A|----\ O-----------/ >> ) >> -------------) >> //) >> (--------| Plasma >> (--------| Plasma >> \\) >> ------------) >> ) >> >> ( are the small mirror at the Earth side of the Asimov >> ) are the big mirror at TC side of the Asimov >> -- / \ Light rays > >Pretty much it. Imagine the ship as a hollow pipe with a plasma in the >inside of the pipe and in frount of it. (The ship surrounds the plasma, >not the other way round.) The microwaves are reflected back and inward by >the forward main ring sial, toward the rear ring sail (drag sail) which >reflects it forward inside the open area of the ship toward the plasma. >It heats and is reflected off the plasma backward. And then after it has reflected backward? The ship needs to absorb or better to reflect the photons in the direction of TC. If it reflects straight back, then it enters the plasma pipe, that must mean trouble. Please tell me what happens after the (first) reflection on the plasma. >> Indeed, that's what I'm saying. If a system is only 10% or even 0.1% >> efficient, then for example a fusion system that uses a 1:1000 ship:fuel >> ratio as well. > >As well what? Efficency is not nessisary for a system to be usable, but a >ship that needs to carry a thousand times its weight in fuel simply can't >be built. I really don't see why, please explain. (See also the last paragraph of this letter.) >You've never suggested how you think such amounts of anti-matter could be >made. Or how we could build such engines. Or store such amounts of >antimater. 2050 is to close for us to overcome all those problems on that >scale. That means fusion is also out of the question! I've heard that the first commercial fusion power plant would be there at 2050. From there it is still a big step to scaling up such a power plant about 1E8 times. And if fusion isn't our source for the beaming station what is? A mirror-array to collect the energy of the Sun would be too large or too difficult to construct. The current electricity capacity of the world is about 3E12 Watt. So all what we have now should be scaled up 1E6 times! Finally we come to the conclusion that doing this in 2050 is completly out of the question. Even going to Alpha Centauri isn't possible, simply because we there isn't a power-source by then that can do the trick. >>How to store the anti-matter? Just like normal matter, create anti-atoms >>and anti-solids. Finally charge it and suspend it in electro/magnetic >>bottles. OK, it sounds easy, but it seems to be possible. > >In theory, but its a big jump from theoretically possible to usable. You are right. But the only experiment done with moving an object by laser light involved a mass of about a milligram. So that would mean that any lightsailing technique is not much more than theory too. What I mean is that probably none of the existing and almost-ready-to-use techniques could bring us to TC. >We went around on that question a lot a few months ago. Yes you have to >bring the crews back. No one would fund a suicide run without a desparte >need, and we don't have one. Staying there isn't necessary suicide! Going back may be a bigger risk. (On that question I didn't vote for a 2-way trip) >> I think that we have to assume that this minimum is possible, otherwise >> no system is possible unless we "invent" anti-gravity, or if we use a >> ship that has much less mass (which is almost impossible). >> So it would be better if one the rules of the SD "discussion" was that a >> minimum (unknown?) power source of 1E18 watt is available in 2040. > >Or limit the discussion to systems and power levels that seem likely. Lower power levels mean not going to TC! Lower levels mean a much longer trip, and we agreed that wasn't our goal. >> Increasing efficiency or affordability make any design more probable and >> feasable. If for example the space shuttle had AI and nanotech. it would >> probably much more saver, reliable and cheaper. > >True, but since we havn't figured out a near lightspeed ship thats more >than marginaly plausible, trying to cut costs on it doesn't mater. All >that would do would be to make a nonfunctional system cheaper. It makes a lot of difference if one needs 1000 Watt or 1000*1000 Watt. For the first a simple petrol-generator will do, but for de latter you need almost a complete power-plant. >> If one makes such a big ship, a lot of things may go wrong and endanger >> the trip. The more complex the ship, the more probable that the trip >> isn't completed. NanoAI will decrease that probability significantly. > >But of course, Nano are about the most complex and unrepairable systems >we've even theorized making. Maybe unrepairable, but there will be many of them, so one or two less doesn't matter. The strength of nano is not only their tinyness, but also their vastness (for small price? and weight). The goal will be that they become selfreproducive in a (hopefully) controlled way. >The odds of finding lifeforms and planets are how to judge. Certainly >we're only taking about a handful of stars within search range. But it >seems likely all of them could have planets, and we have no idea how picky >life is about where it can form. In Sol, earths a yes, Mars is a maybe >(please send unbroken lab gear) Venus I'd bet strongly against. As for >the rest and their moons... ?? > >One thing we can be sure of, none of the planets out there will be >habitable. Earth wouldn't be habitable to us if we hadn't evolved here. Why wouldn't they be habitable? It would be possible that there are already other forms of life there. (Not necessary intelligent) In any event a handfull of starsystems should keep us busy for a couple decades. Obviously past 2100 all the systems were discussing will seem archaic, and our physics quite naive. Probably the next century would keep us busy only by "colonizing" moon and mars. And maybe some nice asteroids for their low gravity. >> I've done some calculations, these show there is not that much profit >> (in energy) when one compares prelaunching with take-all-with-you (from >> now on TAWY). > >So? It would make a critical difference in the fuel mass ratio of the >ship. So, energy stays about the same, or even better it doesn't have to be produced it (the hydrogen) only has to be collected. Why would making a big lump of Hydrogen be so difficult? It doesn't all have to be launched from Earth (asteroids or moons?) Timothy From popserver Sat Dec 23 03:51:28 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["13039" "Fri" "22" "December" "1995" "22:43:22" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "287" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail02.mail.aol.com (mail02.mail.aol.com [152.163.172.66]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id TAA20804 for ; Fri, 22 Dec 1995 19:44:51 -0800 (PST) Received: by mail02.mail.aol.com (8.6.12/8.6.12) id WAA23676; Fri, 22 Dec 1995 22:43:22 -0500 Message-ID: <951222224321_22042979@mail02.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Fri, 22 Dec 1995 22:43:22 -0500 Oh, any idea why the LIT site droped off the SUNSITE server again? >> Timothy re: Kelly >> Subject : Plasma mirror >> >> >>What I meant with no turning, was that it just had to reflect the beam >> >>STRAIGHT back. To do that is has a very precise orientation: the >> >>incoming beam. The mirror does not have to track a moving object, that >> >>is the task of the Earth beaming station. If Earth beams it to the >> >>Asimov, then it also aims to the mirror. because the Asimov and the >> >>retro-mirror are always lined up. >> > >> >That wouldn't work, but eiather way. Straight back is still a direction >> >to aim at, and it couldn't do it. >> >> Is it really that hard to keep the mirror straight? And still, if the beam >> deviates, the Asimov can still follow it (too a certain amount) by >> redirecting its own mirror. Its kind of like balencing a meter square sheet of aluminum foil on the blast from a fire extiquisher, and expect it to never wrinkle or twist. >> Doesn't this problem arise also on the Asimov itself, it too uses a big >> mirror to accelerate, if its mirror is a bit offside, it is out of the beam >> in seconds. If you move 1E8 metres in one second, only minute angles are >> needed to be off the "road" 1E4 metres or so. The ring sail is anchored to the ship. Sort of like a parachute. I.E. a parachute attached to a weight forms a nice shape. Cut the corts and it turns into a lose sheet flutering and twisting down. Unevenness in the beam will tend to cause the ship to difft back and forth, but aslong as the beam is far larger than the sail, and the transmitions failly even (also helped by an oversized beam). It should be managable. >> >We have no real idea whats in interstellar space, but is fair to expect a >> >few comets, asteroids ect; and I don't think we can plan on everything in >> >our way getting neatly blown out of the way. >> >> If there are indeed so many rocks that we have to worry, then we certainly >> should make use of them. How big do you think the chances are that any of >> these lumps comes even near the Asimov? How could you make use of them? Your runing past them at a relativistic speed. Hopefully the odds are low, but prudent designers assume they will have the worst possible luck. >> >NO! A retro reflecter mirror wil not work unless the retro-mirror is much >> >bigger. >> >-If its the same size and the retro mirror is straight in frount of the >> > ship. >> > It will be in the shaddow of the ships drag mirror. So it won't 'see' >> > any of the beam to reflect. >> >-Even if its not in the line of sight. Being the same size as the drag >> > mirror on the ship. It can't reflect anymore energy back to the drag >> > mirror, >> > than the mirror gets directly from earth. So It wouldn't be able to >> > decelerate the ship. >> >> These two remarks mean that you haven't understood how I planned to make >> that retro-mirror! >> It was constructed of two mirrors at a right angle to each other... (See >> previous letters) >> >> A|----\ >> O-----------/ Sorry thought that idea was droped. With this you have two mirrors flaping in the breze trying to aim at something. Your odds of aiming accuratly have droped accordingly. Also you still have to focus back toward a smaller sail on the ship. >> >> ) >> >> -------------) >> >> //) >> >> (--------| Plasma >> >> (--------| Plasma >> >> \\) >> >> ------------) >> >> ) >> >> >> >> ( are the small mirror at the Earth side of the Asimov >> >> ) are the big mirror at TC side of the Asimov >> >> -- / \ Light rays >> > >> >Pretty much it. Imagine the ship as a hollow pipe with a plasma in the >> >inside of the pipe and in frount of it. (The ship surrounds the plasma, >> >not the other way round.) The microwaves are reflected back and inward by >> >the forward main ring sial, toward the rear ring sail (drag sail) which >> >reflects it forward inside the open area of the ship toward the plasma. >> >It heats and is reflected off the plasma backward. >> >> And then after it has reflected backward? The ship needs to absorb or better >> to reflect the photons in the direction of TC. Yes. If you could work out the angles and put a flat drag sail straight behind the ship (inside the rear ring sail that reflected the energy to the plasma) that would be ideal. Assuming the plasma isn't perfectly flat (highly likely) some energy will be reflected outward and it should be accounted for in the design of the ship. >> If it reflects straight back, then it enters the plasma pipe, that must mean trouble. >> Please tell me what happens after the (first) reflection on the plasma. Ideally, the beam reflects straight back toward a flat drag sail behind the ship (and straglers bounce of the inside of the ship tpward the drag sail). The beam is then directed forward toward the plasma again, and bounces back again. The plasma gets an extra boost forward. Then the ship gets an extra push backward. (repeat until beam is lost, absorbed, or canceled out by out of phase other parts of beam.) >> >> Indeed, that's what I'm saying. If a system is only 10% or even 0.1% >> >> efficient, then for example a fusion system that uses a 1:1000 ship:fuel >> >> ratio as well. >> > >> >As well what? Efficency is not nessisary for a system to be usable, but a >> >ship that needs to carry a thousand times its weight in fuel simply can't >> >be built. >> >> I really don't see why, please explain. (See also the last paragraph of this >> letter.) Because you can't build a craft thats engines and structure are so light, strong, and powerfull; that they could carry a weight a thousand times greater than their own and accelerate it at about 1 G. As a mater of fact I'm concerned that a fusion driven ship capable of carrying 40 or 60 times its weight is overly optimistic. (But I haven't gotten aroiund to looking up the numbers in the Bussard papers.) Also of course if the energy to accelerate the fuel doesn't need to be carried in the ship, the ship can get by on less fuel. >> >You've never suggested how you think such amounts of anti-matter could be >> >made. Or how we could build such engines. Or store such amounts of >> >antimater. 2050 is to close for us to overcome all those problems on that >> >scale. >> >> That means fusion is also out of the question! I've heard that the first >> commercial fusion power plant would be there at 2050. From there it is still >> a big step to scaling up such a power plant about 1E8 times. >> And if fusion isn't our source for the beaming station what is? Fusion could be developed in a decade or so if their was any push for it. Possibly power for intersystem space craft might entice someone to invest in the R&D money for it. Though your right. Their are no current plans to do so. Nor for that matter to build enough of a space infastructure to support a project like this. But, if we had usable space launchers. There is a big pent up demand for public and comercial access to space. When that demand starts, building up to the space infastructure we'ld need. Think of how fast aviation and its infastructure developed between 1915 and 1965. >> >>How to store the anti-matter? Just like normal matter, create anti-atoms >> >>and anti-solids. Finally charge it and suspend it in electro/magnetic >> >>bottles. OK, it sounds easy, but it seems to be possible. >> > >> >In theory, but its a big jump from theoretically possible to usable. >> >> You are right. But the only experiment done with moving an object by laser >> light involved a mass of about a milligram. So that would mean that any >> lightsailing technique is not much more than theory too. Actually NASA played around with the idea on a satelight. A couple public groups were trying tyo build and launch a solar sailer in the '80's, but they never finished them. >> What I mean is that probably none of the existing and almost-ready-to-use >> techniques could bring us to TC. To T.C.? Definatly. Thats why we spent so much time on the maser mirrors and such. >> >We went around on that question a lot a few months ago. Yes you have to >> >bring the crews back. No one would fund a suicide run without a desparte >> >need, and we don't have one. >> >> Staying there isn't necessary suicide! Going back may be a bigger risk. If your planing to send yourself to somewhere you can't really live at, and can't come back from, its suicide. If you propose sending others there its murder; and no western government or major group would be allowed to launch such a mission. >> (On that question I didn't vote for a 2-way trip) >> >> >> I think that we have to assume that this minimum is possible, otherwise >> >> no system is possible unless we "invent" anti-gravity, or if we use a >> >> ship that has much less mass (which is almost impossible). >> >> So it would be better if one the rules of the SD "discussion" was that a >> >> minimum (unknown?) power source of 1E18 watt is available in 2040. >> > >> >Or limit the discussion to systems and power levels that seem likely. >> >> Lower power levels mean not going to TC! Lower levels mean a much longer >> trip, and we agreed that wasn't our goal. Agreed. >> >> Increasing efficiency or affordability make any design more probable and >> >> feasable. If for example the space shuttle had AI and nanotech. it would >> >> probably much more saver, reliable and cheaper. >> > >> >True, but since we havn't figured out a near lightspeed ship thats more >> >than marginaly plausible, trying to cut costs on it doesn't mater. All >> >that would do would be to make a nonfunctional system cheaper. >> >> It makes a lot of difference if one needs 1000 Watt or 1000*1000 Watt. For >> the first a simple petrol-generator will do, but for de latter you need >> almost a complete power-plant. If you can build one petrol (gasoline) generator, at worst you can build a thousand others and string them together for a special project. Maybe well start mass producing O'Neil type solar power sattelites. >> >> If one makes such a big ship, a lot of things may go wrong and endanger >> >> the trip. The more complex the ship, the more probable that the trip >> >> isn't completed. NanoAI will decrease that probability significantly. >> > >> >But of course, Nano are about the most complex and unrepairable systems >> >we've even theorized making. >> >> Maybe unrepairable, but there will be many of them, so one or two less >> doesn't matter. The strength of nano is not only their tinyness, but also >> their vastness (for small price? and weight). The goal will be that they >> become selfreproducive in a (hopefully) controlled way. Hopefully. Otherwise we launched a gray goo plague to T.C. ;-) Eiather way its pretty iffy tech, and doesn't solve the fundemental problems. >> >The odds of finding lifeforms and planets are hard to judge. Certainly >> >we're only taking about a handful of stars within search range. But it >> >seems likely all of them could have planets, and we have no idea how picky >> >life is about where it can form. In Sol, earths a yes, Mars is a maybe >> >(please send unbroken lab gear) Venus I'd bet strongly against. As for >> >the rest and their moons... ?? >> > >> >One thing we can be sure of, none of the planets out there will be >> >habitable. Earth wouldn't be habitable to us if we hadn't evolved here. >> >> Why wouldn't they be habitable? It would be possible that there are already >> other forms of life there. (Not necessary intelligent) Agreed. Their is a reasonable chance of finding worlds with ecologies as complex as Earth and with life forms similar to ours in size, complexity, etc... And if you could survive a couple secounds on them outside of a biosuit I'ld be stunned! The history of explorers here on this world, and our present problems with plagues like Ebola, AIDs, Etc, don't speak well for the odds of a carless interstellar explorer. Your microbes, and the planets microbes would rapibly try to digest the alien life forms it sees. >> >> In any event a handfull of starsystems should keep us busy for a >> >> couple decades. Obviously past 2100 all the systems were >> >> discussing will seem archaic, and our physics quite naive. >> >> Probably the next century would keep us busy only by "colonizing" moon and >> mars. And maybe some nice asteroids for their low gravity. True, though I think big platforms harvesting near earth asteroids and comet cores would go first. Moon and Mars lack a human healty gravity, and its much easier to ship the mined cargo from near earth objects around and much richer pickings!! (One estimate places the value of the oil on one average near earth comet core at several hundred billion dollars US!) Which is one of the reasons I expect space development to progress much faster than expected. Free-for-the-taker valuble materials tend to encourage that. ;-) Kelly From popserver Sun Dec 24 00:17:21 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["11133" "Sat" "23" "December" "1995" "23:06:55" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "224" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id OAA18740 for ; Sat, 23 Dec 1995 14:06:03 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA20832 (5.67b/IDA-1.5 for ); Sat, 23 Dec 1995 23:06:45 +0100 Message-Id: <199512232206.AA20832@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sat, 23 Dec 1995 23:06:55 +0100 >Oh, any idea why the LIT site droped off the SUNSITE server again? Yes, they had a major harddisk failure. Timothy re: Kelly Subject : Plasma mirror >> Is it really that hard to keep the mirror straight? And still, if the beam >> deviates, the Asimov can still follow it (too a certain amount) by >> redirecting its own mirror. > >Its kind of like balencing a meter square sheet of aluminum foil on the blast >from a fire extiquisher, and expect it to never wrinkle or twist. You should compare each of the 2 parts of the retro-mirror with a bridge over a valley. The mirror itself would be the road, behind the mirror there would be strenghtening structure, that would be curved just like the bridge. The mirror would stay reasonable flat just like the road that connects both sides of the valley. >The ring sail is anchored to the ship. Sort of like a parachute. I.E. a >parachute attached to a weight forms a nice shape. Cut the corts and it >turns into a lose sheet flutering and twisting down. This assumes the wind is constant and comes always from the same side without small deviations. As soon as the wind comes a bit from aside, the parachute will turn a bit so that its movement is parallel with the incoming wind. >>If there are indeed so many rocks that we have to worry, then we certainly >>should make use of them. How big do you think the chances are that any of >>these lumps comes even near the Asimov? > >How could you make use of them? Your runing past them at a relativistic >speed. Lower an anchor... :) But seriously, we have a minimum of 1E19 Watt available, with that power you could move a mountain (literal). Then why do we need so much power, we are only 2E9 kg? We move at 1E8 m/s relative to that energy, that's why. >Sorry thought that idea was droped. With this you have two mirrors flaping >in the breze trying to aim at something. Your odds of aiming accuratly have >droped accordingly. Also you still have to focus back toward a smaller sail >on the ship. I don't see why these mirrors are flapping, see also the above. >>If it reflects straight back, then it enters the plasma pipe, that must mean >>trouble. Please tell me what happens after the (first) reflection on the >>plasma. > >Ideally, the beam reflects straight back toward a flat drag sail behind the >ship (and straglers bounce of the inside of the ship tpward the drag sail). > The beam is then directed forward toward the plasma again, and bounces back >again. The plasma gets an extra boost forward. Then the ship gets an extra >push backward. (repeat until beam is lost, absorbed, or canceled out by out >of phase other parts of beam.) I assume that the plasma is replenished all the time. So at the same time that the plasma is replenished inside the plasma-pipe, there are also coming reflected photons from the TC side. Doesn't that create a problem? >Because you can't build a craft thats engines and structure are so light, >strong, and powerfull; that they could carry a weight a thousand times >greater than their own and accelerate it at about 1 G. As a mater of fact >I'm concerned that a fusion driven ship capable of carrying 40 or 60 times >its weight is overly optimistic. (But I haven't gotten aroiund to looking up >the numbers in the Bussard papers.) I don't see why you can build a craft of 1E8 kg that can propell itself but not a craft of 1E11 kg. Just scale up the engines. If that isn't possible, the initial acceleration should be less, after a while the ship gets lighter and the acceleration can be increased. >Also of course if the energy to accelerate the fuel doesn't need to be >carried in the ship, the ship can get by on less fuel. Yes, but that would involve a beaming technique. >Fusion could be developed in a decade or so if their was any push for it. > Possibly power for intersystem space craft might entice someone to invest in >the R&D money for it. Though your right. Their are no current plans to do >so. Nor for that matter to build enough of a space infastructure to support >a project like this. How much push did you have in mind? There is already much research going on. Already a few seconds of "controlled" fusion are possible. Development isn't possible yet, because not enough is known about the plasma flows that are used. >But, if we had usable space launchers. There is a big >pent up demand for public and comercial access to space. When that demand >starts, building up to the space infastructure we'ld need. Think of how fast >aviation and its infastructure developed between 1915 and 1965. You yourself told me that you can't compare past developments so easely with future developments. But I don't want to hold this against you, I also see that space will become a bigger and bigger part of the economy. I know that certain commercial firms (General Motors) are developing small easy to produce and relative cheap launchers. >Actually NASA played around with the idea on a satellite. A couple public >groups were trying tyo build and launch a solar sailer in the '80's, but they >never finished them. Wasn't there an experiment with a solarsail last month? >>What I mean is that probably none of the existing and almost-ready-to-use >>techniques could bring us to TC. > >To T.C.? Definatly. Thats why we spent so much time on the maser mirrors >and such. The mirrors might be feasable but how about the maser itself? Making a beam of 1 or 1000 kilometres in radius... that would mean a massive area filled with maser cannons. So actually the beam would consist of many small beams evenly distributed. Say we take a 100x100 km area, that is 1E10 square metres. We need a power of about 1E18 Watt per square kilometre, so if we install one maser per square metre, each maser (there would be 1E10 of them) should need a power of 1E12 Watt. So that means every maser needs its own fusion power plant, meaning 1E10 power plants. These power plants would need a total of about 5000 kg of fuel per second. This story is almost the same for Alpha Centauri as for Tau Ceti the biggest difference is the total time these masers have to be turned on. Or if you lower the acceleration you may devide all numbers by 10 or 100. I hope this makes clear why existing or almost-ready-to-use techniques are not usable. >If your planing to send yourself to somewhere you can't really live at, and >can't come back from, its suicide. If you propose sending others there its >murder; and no western government or major group would be allowed to launch >such a mission. It's just how you want to see it. Confing the crew to 15 years living in a spaceship is bad enough. Giving them another 15 years may be even worse. Probably most people would fail the psychological test only for this reason. Imagine 15 years in the same environment, always busy with the same kind of job, then finally you find a 10 whole planets to build new things. Would they really like to go back? Would it really be such a crime to let those people stay there and try to make a living? Even if it are all rotten planets (which is doubtful) it probably would be better to be there than to be in that stinking old spaceship for another 15 years If we aren't planning on staying there, why go there? If it's just to investigate it may be better to send unmanned probes. (That would be a task for AI) >>Lower power levels mean not going to TC! Lower levels mean a much longer >>trip, and we agreed that wasn't our goal. > >Agreed. So TC is out? >>It makes a lot of difference if one needs 1000 Watt or 1000*1000 Watt. For >>the first a simple petrol-generator will do, but for de latter you need >>almost a complete power-plant. > >If you can build one petrol (gasoline) generator, at worst you can build a >thousand others and string them together for a special project. Maybe well >start mass producing O'Neil type solar power sattelites. String them together, there you said it. Doing that is not as easy as you make it sound. You have to fuel them all, a mayor cloud of smoke would hang around them, no to mention the noise they would make. Other power supplies may not smoke or make noise but tying them together tends to make problems expand non-linear. For example, wires get thicker but their surface does increase at a slower rate, so the heat that is created by resistance has more difficulties to escape. >>Maybe unrepairable, but there will be many of them, so one or two less >>doesn't matter. The strength of nano is not only their tinyness, but also >>their vastness (for small price? and weight). The goal will be that they >>become selfreproducive in a (hopefully) controlled way. > >Hopefully. Otherwise we launched a gray goo plague to T.C. ;-) > >Eiather way its pretty iffy tech, and doesn't solve the fundemental problems. Safety is a fundamental problem. >Agreed. Their is a reasonable chance of finding worlds with ecologies as >complex as Earth and with life forms similar to ours in size, complexity, >etc... And if you could survive a couple secounds on them outside of a >biosuit I'ld be stunned! The history of explorers here on this world, and >our present problems with plagues like Ebola, AIDs, Etc, don't speak well for >the odds of a carless interstellar explorer. Your microbes, and the planets >microbes would rapibly try to digest the alien life forms it sees. I heard that our genes would probably be so different from independant developped species that they would mean no harm at all. But if they weren't we certainly would be able to immunize ourselves. The humane genome project would be completed by then and we would be able to detect and probably cure every virus-disease (including AIDS). The reason for the history of Earth-based explorers is that their genes are so identical to those of the species in the newly dicovered areas. >True, though I think big platforms harvesting near earth asteroids and comet >cores would go first. Moon and Mars lack a human healty gravity, and its >much easier to ship the mined cargo from near earth objects around and much >richer pickings!! (One estimate places the value of the oil on one average >near earth comet core at several hundred billion dollars US!) Which is one >of the reasons I expect space development to progress much faster than >expected. Free-for-the-taker valuble materials tend to encourage that. ;-) Comets are probably not very handy, there are few of them and they have a peculiar orbit. Asteroids would be easier but probably less rich of organic material. Do you know why comets have that much oil? Oil means organic leftovers. And if there is that much of it, that means there is a big chance of life out in the galaxy. As indeed many suggested once you start living on Mars or Moon, you can't go back to Earth easely. Maybe we should look for a low gravity object (a moon), work on the ground and sleep in orbiting space stations with artificial Earth-gravity. Or we should build massive spinning buildings that create 1g. Timothy P.S. Why does your mailer add 2 >'s and a space for replied pieces of text? It looks a bit messy... From popserver Sun Dec 24 22:51:14 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2053" "Sun" "24" "December" "1995" "13:38:30" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "47" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.2/8.7.2) with ESMTP id NAA20762 for ; Sun, 24 Dec 1995 13:32:13 -0800 (PST) Received: from sea-ts1-p16.wolfenet.com (sea-ts1-p16.wolfenet.com [204.157.98.70]) by wolfe.net (8.7.3/8.7) with SMTP id NAA14438; Sun, 24 Dec 1995 13:38:30 -0800 (PST) Message-Id: <199512242138.NAA14438@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Sun, 24 Dec 1995 13:38:30 -0800 (PST) >>If your planing to send yourself to somewhere you can't really live at, and >>can't come back from, its suicide. If you propose sending others there its >>murder; and no western government or major group would be allowed to launch >>such a mission. > >It's just how you want to see it. Confing the crew to 15 years living in a >spaceship is bad enough. Giving them another 15 years may be even worse. >Probably most people would fail the psychological test only for this reason. >Imagine 15 years in the same environment, always busy with the same kind of >job, then finally you find a 10 whole planets to build new things. Would >they really like to go back? Would it really be such a crime to let those >people stay there and try to make a living? Even if it are all rotten >planets (which is doubtful) it probably would be better to be there than to >be in that stinking old spaceship for another 15 years In system travel should give us a good idea of how well people adapt to space travel. A few missions of longer and longer duration to near and then farther planets would help to see the adaptiveness of humans to prolonged space flight. By the time we sent some folks to Titan and back we could refine the problem and work on means to sidestep these. > >If we aren't planning on staying there, why go there? If it's just to >investigate it may be better to send unmanned probes. (That would be a task >for AI) I agree to this. > >So TC is out? So it would seem. >>As indeed many suggested once you start living on Mars or Moon, you can't go >back to Earth easely. Maybe we should look for a low gravity object (a >moon), work on the ground and sleep in orbiting space stations with >artificial Earth-gravity. Or we should build massive spinning buildings that >create 1g. We are going to have to establish a solarsystem based society before we would be able to convince anyone of the need to go anywhere else. Ric PS: A Happy Holiday and a Happy New Years to you all. :-) The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Tue Dec 26 05:05:20 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9161" "Mon" "25" "December" "1995" "18:48:41" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "183" "Fwd: Space Access Update #60 12/24/95 (fwd)" "^From:" nil nil "12" nil "Fwd: Space Access Update #60 12/24/95" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail06.mail.aol.com (mail06.mail.aol.com [152.163.172.108]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA21573 for ; Mon, 25 Dec 1995 15:48:51 -0800 (PST) Received: by mail06.mail.aol.com (8.6.12/8.6.12) id SAA24789; Mon, 25 Dec 1995 18:48:41 -0500 Message-ID: <951225184840_99012300@mail06.mail.aol.com> From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, T.L.G.vanderLinden@student.utwente.nl Subject: Fwd: Space Access Update #60 12/24/95 (fwd) Date: Mon, 25 Dec 1995 18:48:41 -0500 --------------------- Forwarded message: From: doughtd@pr.erau.edu (Donald Doughty) Sender: delta-clipper-approval@world.std.com Reply-to: delta-clipper@europe.std.com To: delta-clipper@world.std.com (DC-X) Date: 95-12-24 23:37:37 EST ---------- Forwarded message ---------- Date: Sun, 24 Dec 1995 10:46:50 -0500 (EST) From: hvanderbilt@BIX.com To: hvanderbilt@bix.com Subject: Space Access Update #60 12/24/95 Space Access Update #60 12/24/95 Copyright 1995 by Space Access Society _______________________________________________________________________ Stories this issue: - Where Have We Been? Where's My Tape? When Is Space Access '96? (Why *has* it been ten weeks since the last SAS Update?) - What The Heck Is Going On Anyway? (Reusable Launch News Summary) -----------------------(SAS Policy Boilerplate)------------------------ Space Access Update is Space Access Society's when-there's-news publication. Space Access Society's goal is to promote affordable access to space for all, period. We believe in concentrating our resources at whatever point looks like yielding maximum progress toward this goal. Right now, we think this means working our tails off trying to get the government to build and fly a high-speed reusable rocket demonstrator, one or more "X-rockets", in the next three years, in order to quickly build up both experience with and confidence in reusable Single-Stage To Orbit (SSTO) technology. The idea is to reduce SSTO technical uncertainty (and thus development risk and cost) while at the same time increasing investor confidence, to the point where SSTO will make sense as a private commercial investment. We have reason to believe we're not far from that point now. Our major current focus is on supporting the government's fully reusable single-stage rocket technology programs, the low-speed DC-XA, and its high-speed followon, the X-33 NASA/DOD/industry cooperative project. With luck and hard work, we should see fully-reusable rocket testbeds flying into space well before the end of this decade, with practical orbital transport projects getting underway. Join us, and help us make it happen. Henry Vanderbilt, Executive Director, Space Access Society To join Space Access Society or buy the SSTO/DC-X V 3.0 video we have for sale (Two hours, includes all eight DC-X flights, X-33, DC-X and SSTO backgrounders, aerospike engine test-stand footage, plus White Sands Missile Range DC-X pre and post flight footage) mail a check to: SAS, 4855 E Warner Rd #24-150, Phoenix AZ 85044. SAS membership with direct email of Space Access Updates is $30 US per year; the SSTO V 3.0 video is $25, $5 off for SAS members, $8 extra for shipping outside the US and Canada, VHS NTSC only. For more info on our upcoming Space Access '96 conference, email: space.access@space-access.org __________________________________________________________________________ Winding Up The Year We've been hearing questions lately, wondering if we'd left the planet ahead of everyone else. We've been busy as hell with some long-term payoff work, and there's been no one earthshaking development in the affordable access field, so we let the next Update slide for a week or two... And now it's over ten weeks, and the little things happening a bit at a time have begun to add up to some interesting trends. It's Update time again - but for now, the condensed holiday version. All the full-length news and informed opinion you can stand Real Soon Now... Those of you waiting for video tapes, all the backordered version 2.0 DC-X/SSTO tapes went into the mail December 22nd. It seems unlikely they'll arrive before Christmas; our apologies for the massive delay. You will find in them a discount certificate for the 3.0 video by way of amends. The long overdue (please, no letter bombs - we bruise easily!) version 3.0 X-33/DC-X/SSTO video now looks like being ready to go to the duplicators the first week of January; backorders will be in the mail immediately thereafter. Yes, we most likely got your order; we've been holding off cashing the checks out of the remnants of a sense of decency and fair play. We hope you'll think the footage we've found is worth the wait. We hope you won't march on SAS HQ with tar and feathers in the meantime... And it's getting toward that time of year again. Our next annual conference, Space Access '96, will be happening April 26-28 1996, Friday evening through Sunday afternoon, once again in Phoenix Arizona. We're going to go bigtime aerospace one of these years, do it during the working week at a posh resort at a thousand bucks a head, but not yet - SA'96 registration is still only $80 if postmarked before January 15th, when it goes up to $90, higher at the door. SA'96 will again be at a hotel within easy shuttle-bus distance of the Phoenix airport; we're currently negotiating with several and should have one nailed down shortly. Previous attendees, tell 'em - this really is worth the trouble to attend. Phoenix is a hub for Southwest and America West, and also served by Western Pacific, Continental, United, Delta, American, etc. There's no lack of cheap airfares if you plan ahead - so be here! Meanwhile, we wish you all a warm and peaceful holiday season, and we'll sign off on that note... What? Tar and feathers? Reusable Launch News Summary Oh, all right. The capsule version of the news... DC-XA is coming along OK, albeit the minor delays are piling up to the point where we'd guess it'll be a few weeks late flying, late spring rather than early. NASA tried to cancel X-34 at the start of November, but there was no wooden stake handy (actually the White House intervened), so it lives still, more or less - development cost is climbing, performance dropping, schedule slipping, and we hear that projected ops costs are rising to more or less the same as Pegasus. Which makes sense, since X- 34 now has as many stages as a Pegasus - carrier aircraft, winged booster, two upper stages - and will likely be at least as complex to integrate and operate. X-33 is doing OK; the picture is beginning to firm up as to what might actually fly and how much it'll cost. Much more on this next Update. The X-33 draft Phase 2 CAN (phase 2 is the actual construction and flight test of one or more X-33's, starting this summer) can be found at, among other places, http://www.space-access.org, our new under- construction web page. (Please, no critiques until we've actually had time to *do* something with the site!) Comments on the draft CAN are due January 22nd; email any comments you have to us at space.access@space-access.org at least one week before that, and we'll run the interesting ones past our advisory board before finalizing SAS's formal comments. After a once-over, we think it looks pretty good; the only "gotcha" we've spotted so far is the clause linking an X-33 go-ahead next summer to continued existance of X-34. Tsk, tsk, naughty naughty, we say - that's a pretty raw attempt to hold X-33 hostage to the highly dubious X-34 project on someone's part. X-33 funding for FY'96 looks fairly assured over on the NASA side, if the HUD/VA/Independent Agencies appropriation ever gets clear of the "train wreck". In theory, there's $25m for reusable rocket work actually appropriated now over in DOD, but the DOD bill was signed only because the White House has to pay for the Bosnia expedition somehow. Look for a major, multi-billion DOD rescissions list in the coming months, and look for an attempt to put our $25m on it. And once we beat that, look for months of delay in releasing the money. This is getting to be a familiar fight, but it's one we've won every time so far. And both McDonnell-Douglas and Lockheed-Martin are investing around $300 million each of private money in upgraded expendable commercial launch vehicles (Delta 3 and Atlas 2AR respectively), and both Kistler Aerospace and Kelly Space & Technology have money and are going ahead with their private reusable space launch ventures. We just might get to the point where government funding is irrelevant to a thriving cheap launch industry sooner than anyone expects. Merry Christmas, y'all. And an interesting New Year... ____________________________________________________________________________ Space Access Society "Reach low orbit and you're halfway to anywhere 4855 E Warner Rd #24-150 in the Solar System." Phoenix AZ 85044 - Robert A. Heinlein 602 431-9283 voice/fax email: "You can't get there from here." space.access@space-access.org - Anonymous - Permission granted to redistribute the full and unaltered text of this - - piece, including the copyright and this notice. All other rights - - reserved. In other words, intact crossposting is strongly encouraged. - From popserver Tue Dec 26 05:05:26 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["11387" "Mon" "25" "December" "1995" "18:48:59" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "288" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout05.mail.aol.com (emout05.mail.aol.com [198.81.10.37]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA21601 for ; Mon, 25 Dec 1995 15:49:29 -0800 (PST) Received: by emout05.mail.aol.com (8.6.12/8.6.12) id SAA14396; Mon, 25 Dec 1995 18:48:59 -0500 Message-ID: <951225184858_23629365@emout05.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Mon, 25 Dec 1995 18:48:59 -0500 > Timothy re: Kelly > Subject : Plasma mirror > > >> Is it really that hard to keep the mirror straight? And still, if the beam > >> deviates, the Asimov can still follow it (too a certain amount) by > >> redirecting its own mirror. > > > >Its kind of like balencing a meter square sheet of aluminum foil on the blast > >from a fire extiquisher, and expect it to never wrinkle or twist. > > You should compare each of the 2 parts of the retro-mirror with a bridge > over a valley. The mirror itself would be the road, behind the mirror there > would be strenghtening structure, that would be curved just like the bridge. > The mirror would stay reasonable flat just like the road that connects both > sides of the valley. Reasonably flat, and optically flat are very different! Optically focused over light-years is even more different. Again, you can't use a 2 part retro mirror since the drag mirror on the ship has to be much smaller. > >The ring sail is anchored to the ship. Sort of like a parachute. I.E. a > >parachute attached to a weight forms a nice shape. Cut the corts and it > >turns into a lose sheet flutering and twisting down. > > This assumes the wind is constant and comes always from the same side > without small deviations. As soon as the wind comes a bit from aside, the > parachute will turn a bit so that its movement is parallel with the incoming > wind. Not a big problem with a point source beam (effectivly point source). Even given unevenness in the beam it should be handelable. > > >>If it reflects straight back, then it enters the plasma pipe, that must mean > >>trouble. Please tell me what happens after the (first) reflection on the > >>plasma. > > > >Ideally, the beam reflects straight back toward a flat drag sail behind the > >ship (and straglers bounce of the inside of the ship tpward the drag sail). > > The beam is then directed forward toward the plasma again, and bounces back > >again. The plasma gets an extra boost forward. Then the ship gets an extra > >push backward. (repeat until beam is lost, absorbed, or canceled out by out > >of phase other parts of beam.) > > I assume that the plasma is replenished all the time. So at the same time > that the plasma is replenished inside the plasma-pipe, there are also coming > reflected photons from the TC side. Doesn't that create a problem? Can't think of any. It actually should help. > >Because you can't build a craft thats engines and structure are so light, > >strong, and powerfull; that they could carry a weight a thousand times > >greater than their own and accelerate it at about 1 G. As a mater of fact > >I'm concerned that a fusion driven ship capable of carrying 40 or 60 times > >its weight is overly optimistic. (But I haven't gotten aroiund to looking up > >the numbers in the Bussard papers.) > > I don't see why you can build a craft of 1E8 kg that can propell itself but > not a craft of 1E11 kg. Just scale up the engines. If that isn't possible, > the initial acceleration should be less, after a while the ship gets lighter > and the acceleration can be increased. Its not the weight, its the mass fraction. You could scale up the craft, but not increase the fraction of its total that is fuel or cargo (well not by much). Given the speeds and time we're talking about, you can't go with a ship with lower accell. > >Also of course if the energy to accelerate the fuel doesn't need to be > >carried in the ship, the ship can get by on less fuel. > > Yes, but that would involve a beaming technique. No, I was talking about my fuel launcher idea, not a beamed power system. > >Fusion could be developed in a decade or so if their was any push for it. > > Possibly power for intersystem space craft might entice someone to invest in > >the R&D money for it. Though your right. Their are no current plans to do > >so. Nor for that matter to build enough of a space infastructure to support > >a project like this. > > How much push did you have in mind? There is already much research going on. > Already a few seconds of "controlled" fusion are possible. Development isn't > possible yet, because not enough is known about the plasma flows that are used. Actually there is very little research going on. Several areas considered more promising than magnetic confinment have no funding due to competition with established programs. In the U.S. each new model car turned out receaves more R&D funding than all of fusion. Given the abundant conventional fuel sources, alternate energy suplies get little interest. > >But, if we had usable space launchers. There is a big > >pent up demand for public and comercial access to space. When that demand > >starts, building up to the space infastructure we'ld need. Think of how fast > >aviation and its infastructure developed between 1915 and 1965. > > You yourself told me that you can't compare past developments so easely with > future developments. --- I beleave I said you should consider dissimilar past developments. > --- But I don't want to hold this against you, I also see > that space will become a bigger and bigger part of the economy. I know that > certain commercial firms (General Motors) are developing small easy to > produce and relative cheap launchers. I don't beleave G.M. has any launcher program? > >Actually NASA played around with the idea on a satellite. A couple public > >groups were trying tyo build and launch a solar sailer in the '80's, but they > >never finished them. > > Wasn't there an experiment with a solarsail last month? Not that I know of. > >If your planing to send yourself to somewhere you can't really live at, and > >can't come back from, its suicide. If you propose sending others there its > >murder; and no western government or major group would be allowed to launch > >such a mission. > > It's just how you want to see it. Confing the crew to 15 years living in a > spaceship is bad enough. Giving them another 15 years may be even worse. > Probably most people would fail the psychological test only for this reason. > Imagine 15 years in the same environment, always busy with the same kind of > job, then finally you find a 10 whole planets to build new things. Would > they really like to go back? Would it really be such a crime to let those > people stay there and try to make a living? Even if it are all rotten > planets (which is doubtful) it probably would be better to be there than to > be in that stinking old spaceship for another 15 years 10 whole planets to build what in? They would have no place to live in other than their ship. No resources to suvive in the ship for more than a few decades (and we have no ability to do better than that). How are they going to survive? What do you mean by having them "stay there and try to make a living"? What is there for them to do that would pay for their keep and supply flights? > If we aren't planning on staying there, why go there? If it's just to > investigate it may be better to send unmanned probes. (That would be > a task for AI) Your expecting a lot out of A.I.s. Humans will probably be more adaptable for some time. Also no one would fund a A.I. exploration flight. Tax payers want to see humans explorer, and lose all interest in programs without human involvement. > >>Lower power levels mean not going to TC! Lower levels mean a much longer > >>trip, and we agreed that wasn't our goal. > > > >Agreed. > > So TC is out? Seems like. > >>Maybe unrepairable, but there will be many of them, so one or two less > >>doesn't matter. The strength of nano is not only their tinyness, but also > >>their vastness (for small price? and weight). The goal will be that they > >>become selfreproducive in a (hopefully) controlled way. > > > >Hopefully. Otherwise we launched a gray goo plague to T.C. ;-) > > > >Eiather way its pretty iffy tech, and doesn't solve the fundemental problems. > > Safety is a fundamental problem. Which they don't help particularly. Thou in our case, unless you can get there at all, mission safty is a moot point. > > Their is a reasonable chance of finding worlds with ecologies as > >complex as Earth and with life forms similar to ours in size, complexity, > >etc... And if you could survive a couple secounds on them outside of a > >biosuit I'ld be stunned! The history of explorers here on this world, and > >our present problems with plagues like Ebola, AIDs, Etc, don't speak well for > >the odds of a carless interstellar explorer. Your microbes, and the planets > >microbes would rapibly try to digest the alien life forms it sees. > > I heard that our genes would probably be so different from independant > developped species that they would mean no harm at all. But if they weren't > we certainly would be able to immunize ourselves. The humane genome project > would be completed by then and we would be able to detect and probably cure > every virus-disease (including AIDS). > The reason for the history of Earth-based explorers is that their genes are > so identical to those of the species in the newly dicovered areas. No, most deseases don't interact with our genetic structure (only viruses do) the rest (molds, bacteria, fungus, etc..) just use us as chemical food or fertalizer. Here we evelved defenses against those deseases, but on an alien ecosphere the counterparts could be radically invulnerable to our defence techneques, and we'ld have no time to evolve new ones. Then again alergies, even to things we've been exposed to for centuries, can kill sometimes us in minuttes. > >True, though I think big platforms harvesting near earth asteroids and comet > >cores would go first. Moon and Mars lack a human healty gravity, and its > >much easier to ship the mined cargo from near earth objects around and much > >richer pickings!! (One estimate places the value of the oil on one average > >near earth comet core at several hundred billion dollars US!) Which is one > >of the reasons I expect space development to progress much faster than > >expected. Free-for-the-taker valuble materials tend to encourage that. ;-) > > Comets are probably not very handy, there are few of them and they have a > peculiar orbit. Asteroids would be easier but probably less rich of organic > material. Do you know why comets have that much oil? Oil means organic > leftovers. And if there is that much of it, that means there is a big chance > of life out in the galaxy. I ment near earth comet cores. Their are a few thousand of them charted, and are easyier to get to than Mars. Technically they don't hold oil, so much as a hydrocarbon sludge. But an oil refinery would process it just the same. > As indeed many suggested once you start living on Mars or Moon, you can't go > back to Earth easely. More precisely the low G would deteriorate your system. Short term you couldn't handel 1 G. Long term you die from cardiovascular, bone, and immune system deterioration. > P.S. Why does your mailer add 2 >'s and a space for replied pieces of text? > It looks a bit messy... Sorry, I thought it was clearer. Is this preferable? Kelly P.S. A, I the only one who remembers to CC Dave Levin on the address list? From popserver Tue Dec 26 18:00:57 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1931" "Tue" "26" "December" "1995" "12:28:20" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "39" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id DAA08324 for ; Tue, 26 Dec 1995 03:27:18 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA15771 (5.67b/IDA-1.5 for ); Tue, 26 Dec 1995 12:28:10 +0100 Message-Id: <199512261128.AA15771@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 26 Dec 1995 12:28:20 +0100 ReplyTo : Ric >In system travel should give us a good idea of how well people adapt to >space travel. A few missions of longer and longer duration to near and then >farther planets would help to see the adaptiveness of humans to prolonged >space flight. By the time we sent some folks to Titan and back we could >refine the problem and work on means to sidestep these. Yes, that will give us a preview. But I think you don't have to wait for that: Imagine living and working in your own house, never allowed to open the door and go outside. When looking outside nothing happens, the stars almost don't change. How would you feel? How many people are there that can survive happely and healty in such an environment? Probably an important feature of the spacevessel would be that it feeled much like Earth's environment. This doesn't mean it should look the same, but several things like a leisure room, a bar, a garden of some sort (and maybe a swimming pool) also crew quarters should not be too small. In fact all kinds of things that would make the spaceship bigger and heavier would make living better. So the dilemmas are size and weight versus crew happyness and healthyness. The point is to make a spacevessel that feels like YOUR environment (home, work, shops). >>As indeed many suggested once you start living on Mars or Moon, you can't go >>back to Earth easely. Maybe we should look for a low gravity object (a >>moon), work on the ground and sleep in orbiting space stations with >>artificial Earth-gravity. Or we should build massive spinning buildings that >>create 1g. > >We are going to have to establish a solarsystem based society before we >would be able to convince anyone of the need to go anywhere else. So if we want to continue the SD project we should make it 2140 instead of 2040. Timothy P.S. Who knows the latest guess for the completion of THE spacestation (Freedom or whatever is leftover). From popserver Tue Dec 26 18:01:15 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4051" "Tue" "26" "December" "1995" "11:01:10" "-0500" "David Levine" "David@interworld.com" nil "72" "RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id HAA12024 for ; Tue, 26 Dec 1995 07:56:56 -0800 (PST) Received: by www with Microsoft Mail id <01BAD381.7A7D1690@www>; Tue, 26 Dec 1995 11:01:16 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD381.7A87EC00" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 11:01:10 -0500 ------ =_NextPart_000_01BAD381.7A87EC00 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Um, gang, you may have noticed that the LIT site has disappeared. In fact, EVERYTHING at SunSITE is --gone--. They had several major failures and are still trying to figure out what went wrong. So far it seems even the backups are unrecoverable. When they restore what they can, I was thinking about moving it all anyway. I don't know yet what's going to happen. Eventually, what I want to do (if possible... I don't know yet), is bring my Linux machine (a 100mhz pentium) into work, plug it in to the network, and give all you guys some disk space and an account. This way LIT can be a much more collaborative thing. Anyway, if that doesn't happen, I'll still find out a way to get as much back on-line as I can. And I don't know if I've gotten all the "issues" of this version of the newsletter - - but when we're back up, if anyone's been archiving the stuff (I've been keeping what I've been getting), please send it to me. One of my big projects at work has been a very powerful search engine... and guess what huge archive is going to benefit from this search engine.... -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD381.7A87EC00 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IhEQAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaAAsA AQAKAAIAEAEBCYABACEAAABBNTM2NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMAA3BwEggAMA DgAAAMsHDAAaAAsAAQAQAAIAFgEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAGwAAAFJFOiBFbmdpbmVlcmluZyBOZXdzbGV0dGVyAKkJAQ2ABAACAAAAAgACAAEDkAYAgAYA ABIAAAALACMAAAAAAAsAKQAAAAAAAwAmAAAAAAADADYAAAAAAB4AcAABAAAAFwAAAEVuZ2luZWVy aW5nIE5ld3NsZXR0ZXIAAAIBcQABAAAAGwAAAAG60yQDyPZuNmk6vBHPrAgAgF8UovAAIYJysQAD AAYQYM1+KgMABxC3AwAAHgAIEAEAAABlAAAAVU0sR0FORyxZT1VNQVlIQVZFTk9USUNFRFRIQVRU SEVMSVRTSVRFSEFTRElTQVBQRUFSRURJTkZBQ1QsRVZFUllUSElOR0FUU1VOU0lURUlTLS1HT05F LS1USEVZSEFEU0VWRQAAAAADABAQAAAAAAMAERADAAAAAgEJEAEAAADYBAAA1AQAAM0HAABMWkZ1 1ElmjP8ACgEPAhUCqAXrAoMAUALyCQIAY2gKwHNldDI3BgAGwwKDMgPFAgBwckJxEeJzdGVtAoMz 9wLkBxMCgzQDRRM1B20CgzY1A8YUyDYSzA/fZjerEswUyDgRDDEZrn0KgMsIzwnZOx85MTIcYAoy xyERIFoKFDI1NQKACoGDDbELYG5nMTAzFFAXCwoUUQvyYxKgIFVtWCwgZyOhJbB5CGAgCQDAeSAR gHZlIG6Qb3RpYwmAIHQRgIcFQCeAJuBMSVQgAJAXE9AmoQQgZAQAYXBwVmUKwAmALgqFSQOgZgUA 0HQlsEVWRVJZQFRISU5HICehU0h1blMoIEUgBAAgKC0tZwIgZSwwLiC/FkAn4CaSJ2ARsCbQcgdA +wqFAMBqBbEqQAMQCHAHkV8AcCdgKVEoQCcgbAMgdFRyeQuAZydwbyowaVpnLvEgCGAFQHcnknef CfAxUQNgI7AssVNvCoX/KkAFwChgLWET4AQgLYEDoMUn0mIA0Gt1cC8hL5FfK5AfQAWgLZICYGUs sVf/J+A0IyaQLwEwkB9ACoUxc+02k2MAcCWwSTFgKLEngL0LgGswUgGgMTIEYHYwUq8zYQdAAyAA cHk40HkssVU4sGQCICcFQGsnAHftCoV5EcAxYycEICxQMFUrEYApIW4ssUU0AXR1/TqheSWwMXM4 sjHhMJE7kEQgKAaQIHBvBBBp3zXiQRAppjuJPJIpJbAsAVZiBRAwYW0mkEwLgHUeeCZhEXALgCbg KGEgYSPQMG1oekCAMdFpuHVtKSvwAjAypncFsPZrJbALUHU6UwuAMIIn0s0scHRGZC9CZ2km0Tqi fyYyMOATsChAA3Am4Cjha/8oQAqwJ0AKhS9DA6AA0AWg/SuQdCyzLAE7ESgDOGE0cPtI4SZgdRFw OfEvkR6xC2B/BuAtsCcgJtE5EjJQCoVB/zrzQsFAcCeDO5AHkDuyPeT9OJEnL/EvxDDAL1ExMkSQ +0ySMJFnPLEosU2iCoU0gvExIG4tbERCKLE4sDhh/ymWT4cnYEG7QGFR8CbRLFBvAkA0ETqiJ9Ii BAEKUHP+IjEgUIIsAS2RAJACIFokczdGLHB3czXwWNEFwC3dXKFiMUM0ETHAJy+RVON/NMBQUzrh LGE9IU1QWPJy30QhOiIKhSfSE8B1DdBAQOtYY18zawngcDBSPzRhR/9TwScgI7BCsQtQKUARsC1h Py9RKGBgFjCgB4AssSBPd0RRWjFDcWIw0ECAA2Bq/QWQdC8hMVFGcSiTXzRaoscmkECQMcByZnUt 1hGw/1+CM+AjsERBQRFIZFnhTHH9J5JoRuBI4V+TJuAsAT1X/01QLHAwwGS2A1JaVGmuVj3zCvRV YDM2DfAkf3AsC1X9GMIxGMAlUHFBA2AT0Cpg/ywhC0Ya0nQDAFAAoHR2cod/C2QVYQvwErB0Mgww dHZE9SbAaSdgTC2AREFPhikg71VgOGAnIFsBRWojXIMqEOVccVcFsGxkdu9393R2gmgCQHA6Ly93 fvBeLkWxBJBGYXxALgWgbUovE8BhDdAvZHkyL9983wBQdm98/3ZISE8BCIH/J2EwoDlQL/FJ8QPw J4BNcf8CEEaAVWABgEEYC0YcYXPwFxrQgh0eYQCJwEAAOQDQjwRgq9O6AQIBRwABAAAANQAAAGM9 VVM7YT0gO3A9SW50ZXJXb3JsZDtsPVByaXZhdGUgTURCLTk1MTIyNjE2MDExMVotNDAAAAAAQAAH MHAtA2Cr07oBQAAIMGCKYmOr07oBHgA9AAEAAAAFAAAAUkU6IAAAAAACARQ0AQAAABAAAABUlKHA KX8QG6WHCAArKiUXTAc= ------ =_NextPart_000_01BAD381.7A87EC00-- From popserver Tue Dec 26 18:01:25 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8463" "Tue" "26" "December" "1995" "17:55:01" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "192" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id IAA13361 for ; Tue, 26 Dec 1995 08:54:06 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA20859 (5.67b/IDA-1.5 for ); Tue, 26 Dec 1995 17:54:55 +0100 Message-Id: <199512261654.AA20859@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Tue, 26 Dec 1995 17:55:01 +0100 Timothy re : Kelly Subject : Plasma mirror >Reasonably flat, and optically flat are very different! Optically focused >over light-years is even more different. OK, I give up... I hoped that this this unflatness would not be too big. But If you can't make a mirror that is flat enough than you can't make a curved mirror that is curved enough. So a curved mirror would spread the light just as much as a flat mirror. So this means that ANY mirror that works over a larger distance is out of the question! >Again, you can't use a 2 part retro mirror since the drag mirror on the ship >has to be much smaller. No, because the two parts of the retro-mirror could have been place further apart (but makes the construction not easier). Beam that missed the mirror || || / || \ A / || \ B Two mirrors A and B at a perpendicular angle /__________________\ but at some distance from each other /|____________________|\ / || || || \ || || || || || || || /\ /\ \/ Beams from Earth Beam to Earth _______ XX XX XX The Asimov The mirrors are connected in some rigid way! >>I assume that the plasma is replenished all the time. So at the same time >>that the plasma is replenished inside the plasma-pipe, there are also coming >>reflected photons from the TC side. Doesn't that create a problem? > >Can't think of any. It actually should help. After rethinking it, I see what you mean. The only thing I'm not sure about is what the physics of plasma reflection are. We may reflect radio-waves to the ionosphere everyday but how does it work? And does it work in the Asimov also? I don't know how big the plasma-tube is going to be but at certain radiation-densities materials get blown up, so you don't even need to ionize the molecules yourself to create a plasma. >Its not the weight, its the mass fraction. You could scale up the craft, but >not increase the fraction of its total that is fuel or cargo (well not by >much). Given the speeds and time we're talking about, you can't go with a >ship with lower accell. Yes, I understood that. But do the engines take the most of the weight? Or in other words, what percentage of the ship (without fuel) is reserved for the engine? If that percentage is small it may be possible to scale up the engines a bit. But indeed there is a limit, only where is that limit? Ideally the weight of the engine grows slower than its power: Make an engine twice as big doubles the power, but the weight increases with the squareroot of 2. > > >Also of course if the energy to accelerate the fuel doesn't need to be > > >carried in the ship, the ship can get by on less fuel. > > > > Yes, but that would involve a beaming technique. > >No, I was talking about my fuel launcher idea, not a beamed power system. Probably launching is even more difficult than beaming. >>How much push did you have in mind? There is already much research going on. >>Already a few seconds of "controlled" fusion are possible. Development isn't >>possible yet, because not enough is known about the plasma flows that are >>used. > >Actually there is very little research going on. Several areas considered >more promising than magnetic confinment have no funding due to competition >with established programs. In the U.S. each new model car turned out >receaves more R&D funding than all of fusion. Given the abundant conventional >fuel sources, alternate energy suplies get little interest. Here in the Europe (also in the Netherlands) there are several institutes busy. Most of the research is in a very early stage. Spending more money may help a bit but not that much as you would hope. Some things just can't go any faster. Besides that, it is not fair to assume that money alone can change research that fast, otherwise antimatter may become a possibility too. >I don't beleave G.M. has any launcher program? You're right, after some research and your forwarded letter, I figured it was the X-33 that I had in mind, and GM should be Lockheed Martin Skunk Works, McDonnell Douglas Aerospace and Rockwell International Corp. >>Wasn't there an experiment with a solarsail last month? > >Not that I know of. I will try finding some info, if I know more I'll let you know. >10 whole planets to build what in? They would have no place to live in other >than their ship. No resources to suvive in the ship for more than a few >decades (and we have no ability to do better than that). How are they going >to survive? What do you mean by having them "stay there and try to make a >living"? What is there for them to do that would pay for their keep and >supply flights? My guess was that they would construct a pre-fab habitat and from there they would expand. Being on a planet gives you much more resources and savety than a spaceship. Not all planets will be equal favourable, but a solid planet the size of Earth will be better than a spaceship after the main habitats are equipped. > > If we aren't planning on staying there, why go there? If it's just to > > investigate it may be better to send unmanned probes. (That would be > > a task for AI) > >Your expecting a lot out of A.I.s. Humans will probably be more adaptable >for some time. Also no one would fund a A.I. exploration flight. Tax payers >want to see humans explorer, and lose all interest in programs without human >involvement. To see? There won't be a live television show with interactive conversations. By the time Earth gets the first message of landing, the crew is already on their way back. Also would you pay money now to see a spectacular show that happens in 30 years? And indeed I am expecting a lot of AI, humans may be more adaptable for a while, but have lots of limitations that "machines" don't have. >> So TC is out? > >Seems like. So where to and when is our new goal? Until now only fusion may bring us out of the solar system within reasonable time. Even if you use a beam, the fusion is necessary to maintain the beam. >No, most deseases don't interact with our genetic structure (only viruses do) >the rest (molds, bacteria, fungus, etc..) just use us as chemical food or >fertalizer. Here we evelved defenses against those deseases, but on an alien >ecosphere the counterparts could be radically invulnerable to our defence >techneques, and we'ld have no time to evolve new ones. > >Then again alergies, even to things we've been exposed to for centuries, can >kill sometimes us in minuttes. Is there any hope for us? Our best hope was to find a living planet, full of life and oxigen. Now it seems that it is better to find a barren planet with no life at all. Do we indeed have not enough time to develop a anti-bodies against these diseases? We indeed should be very careful, but that doesn't mean that after we have found most anti-bodies we can live there. >I ment near earth comet cores. Their are a few thousand of them charted, and >are easyier to get to than Mars. Comet cores? I'm not sure anymore what you mean, what kind of orbit do they have? Elliptical or (near) circular? And do they turn around the Sun or the Earth? How big are they? >More precisely the low G would deteriorate your system. Short term you >couldn't handel 1 G. Long term you die from cardiovascular, bone, and immune >system deterioration. Oh, I didn't know that it was that serious. But I assume we can adapt to a thirth of Earth's gravity or is that still to little? >Sorry, I thought it was clearer. Is this preferable? Unfortunately not, the problem was not the double > but the three (>> ) characters added, that makes that all lines are broken off and one word is shown on the next line. If the you add only one > (no spaces) this word-wrap happens less often. Probably Steve has "trouble" with everyone because he use lines of 60 characters or so. >P.S. >A, I the only one who remembers to CC Dave Levin on the address list? I've never received a (personal) notice from Dave, he just left me (us?) in the dark and I always had to hear from some others that they had made contact with him. The least he could have done was send a (general) note telling he had no time for the SD-project anymore. In fact the only message I got from him was the one of December 17th. So in short, I'm a disappointed by Dave's performance. Timothy From popserver Tue Dec 26 18:01:31 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1785" "Tue" "26" "December" "1995" "11:09:19" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "26" "possible LIT site." "^From:" nil nil "12" nil "possible LIT site." nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id JAA13724 for ; Tue, 26 Dec 1995 09:09:04 -0800 (PST) Received: by maroon.tc.umn.edu; Tue, 26 Dec 95 11:09:20 -0600 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: David Levine cc: "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: possible LIT site. Date: Tue, 26 Dec 1995 11:09:19 -0600 (CST) Ok, I have 10 Meg of Web space, I don't have a forms capability yet, but I imagine that if I had a legitamate reason for needing it, then it would be granted (and maybe some more disk space to boot.) let me know if This would work, so I can get started on the begging asa soon as possible. If you want, you can get everything but the forms stuff right now, my only limit is 10 megs. Perhaps now would be the time to talk about paying our way. I would be willing to part with $20.00 (US) per year to see this continue. (of course getting the web space for free is better, but if we are paying our own way, then we'd have the right to expect it to be up, or complain if it was not) I am just throwing the $20 figure out as my personal resistance point. beyond that, i don't think i could afford it. I'm just a poor college student! ideally, the webspace cost should be split as many ways as we can, and those who contribute get nothing more than name recognition (and maybe the right to put a link on the LIT web page -- Hmm.... Kinda like advertising. no, scratch that. A lot like advertising) maybe we could approach various aerospace companies and get them to help defray the cost, they could then put links to their web pages. A few tens of megabytes of webspace shoud not be that expensive, I've seen quotes in various magazines from $30 (US) for 10 MB on up. I would think that for as little as $100 a year, we could have a very nice website with lots and lots of room. Counting heads that i see here often, (no pressure, I'm just thinking out loud) me, Dave, Kelly, Ric, Timothy, Steve. That's 6 people who contribute regularly, would bring the price down to $16.67 each. the more people who help, the less each of us would have to pay. From popserver Tue Dec 26 18:01:33 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2139" "Tue" "26" "December" "1995" "12:18:04" "-0500" "David Levine" "David@interworld.com" nil "43" "RE: possible LIT site." "^From:" nil nil "12" nil "possible LIT site." nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id JAA13822 for ; Tue, 26 Dec 1995 09:13:41 -0800 (PST) Received: by www with Microsoft Mail id <01BAD38C.376EA430@www>; Tue, 26 Dec 1995 12:18:08 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD38C.3774BEB0" From: David Levine To: "'Kevin C Houston'" Cc: "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "T.L.G.vanderLinden@student.utwente.nl" Cc: "zkulpa@zmit1.ippt.gov.pl" Subject: RE: possible LIT site. Date: Tue, 26 Dec 1995 12:18:04 -0500 ------ =_NextPart_000_01BAD38C.3774BEB0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable It definitely sounds like an interesting possibility, but let me see if I= can get something set up at work first. Free is always better. -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD38C.3774BEB0 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IgkRAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaAAwA EgAEAAIAHAEBCYABACEAAABCRTM2NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMABIBwEggAMA DgAAAMsHDAAaAAwAEgAIAAIAIAEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAFwAAAFJFOiBwb3NzaWJsZSBMSVQgc2l0ZS4AXgcBDYAEAAIAAAACAAIAAQOQBgCwAwAAEgAA AAsAIwAAAAAACwApAAAAAAADACYAAAAAAAMANgAAAAAAHgBwAAEAAAATAAAAcG9zc2libGUgTElU IHNpdGUuAAACAXEAAQAAABsAAAAButO1g1n2bja9OrwRz6wIAIBfFKLwAAAN/PIAAwAGELCrzsYD AAcQ2QAAAB4ACBABAAAAZQAAAElUREVGSU5JVEVMWVNPVU5EU0xJS0VBTklOVEVSRVNUSU5HUE9T U0lCSUxJVFksQlVUTEVUTUVTRUVJRklDQU5HRVRTT01FVEhJTkdTRVRVUEFUV09SS0ZJUlNURlJF RUlTQUwAAAAAAwAQEAAAAAADABEQAwAAAAIBCRABAAAACwIAAAcCAACyAwAATFpGdSZ+SeD/AAoB DwIVAqgF6wKDAFAC8gkCAGNoCsBzZXQyNwYABsMCgzIDxQIAcHJCcRHic3RlbQKDM/cC5AcTAoM0 A0UTNQdtAoM2NQPGFMg2EswP32Y3qxLMFMg4EQwxGa59CoDLCM8J2TsfOTEyHGAKMschESBaChQy NTUCgAqBgw2xC2BuZzEwMxRQlwsKFFEL8mMSoCBJBUALDbELgGkT0Gx5IHMJCGBuZAQgbGlrZX4g A5ELgBPQH0ATwAuAZ8ggcG8EEGliAxAmEKB5LCBidQVAbBHAXiAHgCZgCeAnUGYlgCB6YwORZxHA CoUmcAeAdMZoJ+IRsSB1cCcgBUAydwWwayAl4BGgdC54ICBGCdEnUAQgB0B33mETsCjgEcAngS4K iybg7DM2DfAkfyAKjwuRGMK+MRjAJVAvkQNgE9BjBUD8LS0LRhrSMlMAUACgMsb/MNcLZBVhC/AS sDKCDDAyxgBEYXZpZCBMZUk3kG5lMNVBcAtQaecqMCfQAiAgRSOwOAEEkJczMCWAJ3JXBbBsZDU/ CzZHMsZoAkBwOi8vunc9QC4nYyxROpAuBaCUbS8TwGEN0C9kN4K+LzsvAFA0vztPNJhIJxCGdAiB N7B0byBrAxD/AyApcQPwK1AnICyQLGEm4P0BgC5FUEDtHGEyQBrQQG0FHmEASBAAQAA5AHAj7x22 07oBAgFHAAEAAAA1AAAAYz1VUzthPSA7cD1JbnRlcldvcmxkO2w9UHJpdmF0ZSBNREItOTUxMjI2 MTcxODA0Wi00MQAAAABAAAcw8MHtHbbTugFAAAgwMOBKILbTugEeAD0AAQAAAAUAAABSRTogAAAA AAIBFDQBAAAAEAAAAFSUocApfxAbpYcIACsqJRcXAA== ------ =_NextPart_000_01BAD38C.3774BEB0-- From popserver Tue Dec 26 19:12:25 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5384" "Tue" "26" "December" "1995" "13:06:58" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "99" "RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id LAA17932 for ; Tue, 26 Dec 1995 11:06:43 -0800 (PST) Received: by maroon.tc.umn.edu; Tue, 26 Dec 95 13:06:59 -0600 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: David Levine cc: "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 13:06:58 -0600 (CST) To: All Re: various. Bio interaction between earth and E.T. organisms. first, I believe that any viral infection is not possible, due to the totally arbitrary rna to protien coding system that earth biology uses. Of course all this assumes that the ET biology uses DNA/RNA Glucose ATP systems, but i do have sound Therodynamic/chemical reasons for thinking this is the case. bacteria/fungi on the other hand may pose a serious threat suposing that our systems are even remotely similar, I think it will come down to how long that particular ecosystem has been evolving. if it has been a hort while, then i think that or immune responeses will likely have seen a particular attack statagy before, and will know what to do. if the ET biology has been around longer than us, then I suspect that we will be more vulnerable. however, many earthly bacteria exploit specific weaknesses in our defenses in order to enter our systems. Alien bacteria would not be designed for this. Also, our immune system would probably go into hyperdrive if it was presented with a truely alien protein. I believe that Kelly is right when he identifies allergic reactions as one of the main health problems to be faced. This doesn't even consider what a nasty little fungus like yeast (deposited on the ground the first time you tried to spit out the foul smelling pollen that was making your throat squeeze shut) would do to an alien ecosytem. you might think it's kinda cute the way they take sugar and make alcohol, but I'll bet that just about every other biosystem we ever encounter will think that it's a vile poison. and won't have any idea that making penicillin would get rid of it. this is not to say that a alien ecosystem would be totally useless to us. who know what wonders we may find. how bout an organism that can "grow" silicon chips? of solar cells? perhaps some organism lives in a metal rich environment and can really concentrate metal ores. Perhaps, perhaps, perhaps. I could go on all day, how bout a critter that _likes_ 70 % ethanol (I'll bet that many companies would love to make brandy without having to distill) bacteria that excrete oil, or plastic, or ones that prefer it as a food source. the list goes on and on, and I'm very willing to bet that none of these creatures will be the first exploitable alien lifeform. and I'd further bet that the universe is not only stranger than I imagined, it's stranger than i _can_ imagine. In short, A totally barren 1 G planent would be ideal for colonization, but totally boring for study. To: all Re: mission Ok, I think we all have come slam up against a brick wall. Sending 1 E+09 Kg _any_ distance and coming back to rest WRT the target system is turning into a Herculean task. The charter says that we have remote sensing clues of a biosphere. we also have a public mandate for sending some people there to study it. I think perhaps it's time to either put the "Asimov" on a diet, or approach the problem from the other end. To put the "Asimov" on a diet, I'd suggest at least a thousand fold reduction in payload down to 1E+05 Kg I think this rules out self sustained mission, and requires a return. I still think we can go at 1 G, and use a MARS for the engine, but in order to over come the photon thrust, we're going to have to bring more reaction mass ( and use a slower exhaust velocity). for the return trip, I'd suggest scrapping the lineac entirely, and relying on photonic thrust for both portions of the trip. this means that some payload capacity will have to be devoted to maser transmitter control packages, but i don't see this as a real problem. the crew should be pared down to no more than 100 people, and the return module can totaly scrap the hab ring which can then be left in the target system as a stepping stone for a follow up crew if one is deemed desirable I'll follow this up with some hard numbers later,But, one thing that strikes me off hand is this, for reflection, p= 2E/C this is great for acelerating. for absorbtion, p=E/C this is a smaller amount of photonic thrust to overcome. so for example, a energy beam that provides 10 m/s^2 acceleration via light pressure only needs a 15 m/s^s deceleration from the engines to equal 10 m/s^2 total. and if it takes a 1000 to 1 RM to payload ratio, then that is the cost. and we just have to live with it. but once you get 100 people and a number of maser arrays in orbit around another star system, then sending a follow up mission is relatively easy the second option is to design this mission as if we had _no_ long range information on nearby systems, and design a small ~ 5000 Kg robot. to explore nearby systems, and return pictures and other information about every system in a 20 ly. radius. we might not have to slow down entirely, a .5 C flyby might work here. and perhaps a magnetic turning might work for some long range steering. The robots should be small and low-cost, so that is we lose a few, it's no biggie. then to luanch, we could use a particle luancher, (just like a solar sail, but you use charged particles and a heavier acceleration factor) and once the probes are up to speed, we don't bother with them again. well, my connection is getting slow, so I'll send this and wait til I get home to send the rest. Kevin From popserver Tue Dec 26 23:17:42 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["290" "Tue" "26" "December" "1995" "18:13:43" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "6" "Re: RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout04.mail.aol.com (emout04.mail.aol.com [198.81.10.12]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA28137 for ; Tue, 26 Dec 1995 15:13:13 -0800 (PST) Received: by emout04.mail.aol.com (8.6.12/8.6.12) id SAA05198; Tue, 26 Dec 1995 18:13:43 -0500 Message-ID: <951226181342_79266998@emout04.mail.aol.com> From: KellySt@aol.com To: David@interworld.com, hous0042@maroon.tc.umn.edu, jim@bogie2.bio.purdue.edu, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, zkulpa@zmit1.ippt.gov.pl Subject: Re: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 18:13:43 -0500 Sunsite lost the archives TOO!!? You've got to be kidding? I was woundering what happend. One day I signed on to use some of the software, and the next day it said it could find LIT. I hope you have a lot of back ups? I think I have about all of the newsletters, if that helps. Kelly From popserver Tue Dec 26 23:17:43 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["15625" "Tue" "26" "December" "1995" "18:13:34" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "313" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail02.mail.aol.com (mail02.mail.aol.com [152.163.172.66]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA28198 for ; Tue, 26 Dec 1995 15:14:11 -0800 (PST) Received: by mail02.mail.aol.com (8.6.12/8.6.12) id SAA07175; Tue, 26 Dec 1995 18:13:34 -0500 Message-ID: <951226181334_79266919@mail02.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Tue, 26 Dec 1995 18:13:34 -0500 Kelly Re Timothy >> Timothy re : Kelly >>Subject : Plasma mirror >> >>>Reasonably flat, and optically flat are very different! Optically focused >>>over light-years is even more different. >> >>OK, I give up... I hoped that this this unflatness would not be too big. >>But If you can't make a mirror that is flat enough than you can't make a >>curved mirror that is curved enough. So a curved mirror would spread >>the light just as much as a flat mirror. So this means that ANY mirror >>that works over a larger distance is out of the question! Seems unavoidable. >>>>I assume that the plasma is replenished all the time. So at the same time >>>>that the plasma is replenished inside the plasma-pipe, there are also coming >>>>reflected photons from the TC side. Doesn't that create a problem? >>> >>>Can't think of any. It actually should help. >> >>After rethinking it, I see what you mean. >>The only thing I'm not sure about is what the physics of plasma reflection >>are. We may reflect radio-waves to the ionosphere everyday but how does it >>work? And does it work in the Asimov also? It would certainly involve a much larger scale, and I don't know what the reflection efficency is. Or how much mass would need to be ionized to keep up the reflection. One thing for certain, the stuff will be HOT! >>>Its not the weight, its the mass fraction. You could scale up the craft, but >>>not increase the fraction of its total that is fuel or cargo (well not by >>>much). Given the speeds and time we're talking about, you can't go with a >>>ship with lower accell. >> >>Yes, I understood that. But do the engines take the most of the weight? Or >>in other words, what percentage of the ship (without fuel) is reserved for >>the engine? If that percentage is small it may be possible to scale up the >>engines a bit. But indeed there is a limit, only where is that limit? >>Ideally the weight of the engine grows slower than its power: Make an engine >>twice as big doubles the power, but the weight increases with the squareroot >>of 2. Hard to say. The best engines Iever heard of were liquid fueld rocket engines. The engines can produce thrust over a hundred times their own weight. The Bussard fusion/electrics produce about 6 times their weight. But scaled up and eliminatring the weight of the vacume chamber might make it up to the 10's to 1 ration? (I hope.) >>>>How much push did you have in mind? There is already much research >>>>going on. Already a few seconds of "controlled" fusion are possible. >>>>Development isn't possible yet, because not enough is known about the >>>>plasma flows that are used. >>> >>>Actually there is very little research going on. Several areas >>>considered more promising than magnetic confinment have no funding >>>due to competitionwith established programs. In the U.S. each new >>>model car turned out receaves more R&D funding than all of fusion. >>>Given the abundant conventional fuel sources, alternate energy suplies >>>get little interest. >> >>Here in the Europe (also in the Netherlands) there are several institutes >>busy. Most of the research is in a very early stage. Spending more money >>may help a bit but not that much as you would hope. Some things just >>can't go any faster. Besides that, it is not fair to assume that money >>alone can change research that fast, otherwise antimatter may become >>a possibility too. That would be true if all major areas of research were being investigated and resonably well funded. But most areas of fusion research that I know of have no funding. Magnetic plasma fusion is geting funded, but at least in the US the systems are dead ends. Even if they worked they'ld be useless (to large to be intergrated into the power grid.). Where as more inovative designs that are considered more promising (like Bussards among others) are geting no funding. >>>I don't beleave G.M. has any launcher program? >> >>You're right, after some research and your forwarded letter, I figured it >>was the X-33 that I had in mind, and GM should be Lockheed Martin Skunk >>Works, McDonnell Douglas Aerospace and Rockwell International Corp. Oh yeah, the single stage to orbit program (SSTO). My excorperation, and the NASA department I used to work at in NASA headquarters were working on that program. Increadable potential. It could cut costs to orbit by a factor of 100! Fed Ex is even rumored to be seriously interested in using them for suborbital intercontenental mail carriers. >>>10 whole planets to build what in? They would have no place to live in >>>other than their ship. No resources to suvive in the ship for more than >>>a few decades (and we have no ability to do better than that). How are >>>they going to survive? What do you mean by having them "stay there >>>and try to make a living"? What is there for them to do that would pay >>>for their keep and supply flights? >> >>My guess was that they would construct a pre-fab habitat and from >>there they would expand. Being on a planet gives you much more >>resources and savety than a spaceship. Not all planets will be equal >>favourable, but a solid planet the size of Earth will be better than a >>spaceship after the main habitats are equipped. I'ld debate that. Since your stuck in an artificial habitat anyway, one in space has easy access to all the floating ores and raw materials in the solar system. Much of which would be hard to get at on a planet (ever see a strip mine) and much harder to transport. I'm a firm beleaver that heavy industry will largely move off earth in a century or two. If your already off planet and in a starship, trying to set up on a planet would be hellish. >>> > If we aren't planning on staying there, why go there? If it's just to >>> > investigate it may be better to send unmanned probes. (That would >>> > be a task for AI) >>> >>>Your expecting a lot out of A.I.s. Humans will probably be more >>>adaptable for some time. Also no one would fund a A.I. exploration >>>flight. Tax payers want to see humans explorer, and lose all interest >>>in programs without human involvement. >> >>To see? There won't be a live television show with interactive >>conversations. By the time Earth gets the first message of landing, the >>crew is already on their way back. Also would you pay money now to see >>a spectacular show that happens in 30 years? People won't see it right away, but they will know people are out there. I think that would be enough to get public interest. I know public interest in robot probes is near nill. As NASA constantly found. Robots were thought of as scout craft for maned expiditions. If no manned folowups were planed (and frequently mentioned) public interest in funding the robots droped way off. Generally a so what atitude. Drove the Robot probe teams CRAZY! >>>> So TC is out? >>> >>>Seems like. >> >>So where to and when is our new goal? Until now only fusion may bring >>us out of the solar system within reasonable time. Even if you use a >>beam, the fusion is necessary to maintain the beam. Well you could power the beam with big solar electric power platforms in space. (The kind of stuff the L-5 socyety kept proposing to power earth.) >>>No, most deseases don't interact with our genetic structure (only viruses do) >>>the rest (molds, bacteria, fungus, etc..) just use us as chemical food or >>>fertalizer. Here we evelved defenses against those deseases, but on an >>>alien ecosphere the counterparts could be radically invulnerable to our >>>defence techneques, and we'ld have no time to evolve new ones. >>> >>>Then again alergies, even to things we've been exposed to for >>>centuries, can kill sometimes us in minuttes. >> >>Is there any hope for us? Our best hope was to find a living planet, full >>of life and oxigen. Now it seems that it is better to find a barren planet >>with no life at all. I would definatly prefer a dead world as a possible colony site over a lush one like earth. Wouldn't be as interesting to study, but much more survivable. The problem is any world that could support us, probably has life. >>Do we indeed have not enough time to develop a anti-bodies against >> these diseases? We indeed should be very careful, but that doesn't >> mean that after we have found most anti-bodies we can live there. Hell, we're still trying to find cures for all the plagues on earth. So far our best luck seem to be in destroying the worst sections of the ecology (draining wetlands, fogging everything with pestasides, etc..) and building urban semi-ecologies. Most of the habited areas of the developed world (europe, North America, etc..) do this so routinely we don't even notice anymore. But then living in a coutry thats largly under sea level I hardly have to tell you. ;) >>>I ment near earth comet cores. Their are a few thousand of them >>>charted, and are easyier to get to than Mars. >> >>Comet cores? I'm not sure anymore what you mean, what kind of orbit >>do they have? Elliptical or (near) circular? And do they turn around the >>Sun or the Earth? How big are they? Near earth in that the inner part of their orbit come in near to earths orbit, or farther in than it. The outer orbits are generally farther in then jupiter. Somethimes closer in than Mars. After bein in that close for a while. Most of the light volitals melt away, and the outer surface gets covered over by rock. That crust helps shield the reset from sunlight. Compasition is estimated (by weight) at 1/3rd water ice, 1/3rd rock and metalic ores, 1/3rd hydrocarbon sludge (thick cride oil). Size varies. 5 kilometer across ones are fairly common. (Weight 50 billion metric tons.) Estimates are about that there are a few thousand about that size in near earth space. Possibly more asteroids. (It surprising we don't get more impacts!) >>>More precisely the low G would deteriorate your system. Short term >>>you couldn't handel 1 G. Long term you die from cardiovascular, bone, >>>and immune system deterioration. >> >>Oh, I didn't know that it was that serious. But I assume we can adapt to >>a thirth of Earth's gravity or is that still to little? No one really knows. Its assumed you'ld have the same problems, just slower acting. >>>P.S. >>>A, I the only one who remembers to CC Dave Levin on the address list? >> >>I've never received a (personal) notice from Dave, he just left me (us?) >>in the dark and I always had to hear from some others that they had >>made contact with him. The least he could have done was send a >>(general) note telling he had no time for the SD-project anymore. >>In fact the only message I got from him was the one of December 17th. >>So in short, I'm a disappointed by Dave's performance. You have a point. Certainly droping the Newsletter functions off line for .. what is it 2-3 months now? Doesn't speak well for his enthusiasm. Then again the participation has been kind of slight in general lately. Kelly RE Kevin >>To: All >>Re: various. >> >>Bio interaction between earth and E.T. organisms. >> >>first, I believe that any viral infection is not possible, due to the >>totally arbitrary rna to protien coding system that earth biology uses. >> >>Of course all this assumes that the ET biology uses DNA/RNA Glucose >>ATP systems, but i do have sound Therodynamic/chemical reasons for >>thinking this is the -=--- Big snip ----- >> >>In short, A totally barren 1 G planent would be ideal for colonization, >>but totally boring for study. I agree. Its a topic that doesn't get talked about much, but the idea of steping out of a ship on an alien world taking a breath is really shallow. I guess we're all just used to decontaminated parks, or advanced medicines, or something. On the other hand a real alien ecology could be fantastically interesting! >>To: all >>Re: mission >> >>Ok, I think we all have come slam up against a brick wall. Sending >>1 E+09 Kg _any_ distance and coming back to rest WRT the target >>system is turning into a Herculean task. >> >>The charter says that we have remote sensing clues of a biosphere. we >>also have a public mandate for sending some people there to study it. >> >>I think perhaps it's time to either put the "Asimov" on a diet, or >>approach the problem from the other end. To put the "Asimov" on a diet, >>I'd suggest at least a thousand fold reduction in payload down to >> 1E+05 Kg I think we're more stuck than that. We haven't figured out any idea for slowing down a sail or MARS driven ship from relativistic speeds. NOt just not doing it on that scale. We haven't a handel on how to do it at all! >>I think this rules out self sustained mission, and requires a return. I >>still think we can go at 1 G, and use a MARS for the engine, but in order >>to over come the photon thrust, we're going to have to bring more >>reaction mass ( and use a slower exhaust velocity). for the return trip, >>I'd suggest scrapping the lineac entirely, and relying on photonic thrust >>for both portions of the trip. this means that some payload capacity >>will have to be devoted to maser transmitter control packages, but i >>don't see this as a real problem. the crew should be pared down to no >>more than 100 people, and the return module can totaly scrap the hab ring >>which can then be left in the target system as a stepping stone for a >>follow up crew if one is deemed desirable >>I'll follow this up with some hard numbers later,But, one thing that >>strikes me off hand is this, for reflection, p= 2E/C this is great for >>acelerating. for absorbtion, p=E/C this is a smaller amount of photonic >>thrust to overcome. so for example, a energy beam that provides 10 m/s^2 >>acceleration via light pressure only needs a 15 m/s^s deceleration from >>the engines to equal 10 m/s^2 total. and if it takes a 1000 to 1 RM to >>payload ratio, then that is the cost. and we just have to live with it. >>but once you get 100 people and a number of maser arrays in orbit around >>another star system, then sending a follow up mission is relatively easy How do you get a 1000 - 1 mass ration ship to move? Can we scale down the ship that much? We need the hab centrafuge to keep the crew alive and healthy, and that dictates about a 200 meter diameter ring. Fiting that and the systems and sypplies all in 1E+5 kg seems unlikely. (Thats the weight of the shutle orbiter. Or did you mean 1E+5 tons?) Adding in the construction equipment fort big maser arrays makes it even harder. >>the second option is to design this mission as if we had _no_ long range >>information on nearby systems, and design a small ~ 5000 Kg robot. to >>explore nearby systems, and return pictures and other information about >>every system in a 20 ly. radius. we might not have to slow down entirely, >>a .5 C flyby might work here. and perhaps a magnetic turning might >>work for some long range steering. The robots should be small and >>low-cost, so that is we lose a few, it's no biggie. then to luanch, we >>could use a particle luancher, (just like a solar sail, but you use >>charged particles and a heavier acceleration factor) and once the probes >>are up to speed, we don't bother with them again. It would seem you could get about as much info from a large teklescope array in Sol orbit, and get results now! From popserver Tue Dec 26 23:33:08 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8492" "Tue" "26" "December" "1995" "18:34:02" "-0500" "David Levine" "David@interworld.com" nil "157" "RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA28979 for ; Tue, 26 Dec 1995 15:29:43 -0800 (PST) Received: by www with Microsoft Mail id <01BAD3C0.BFD26C10@www>; Tue, 26 Dec 1995 18:34:11 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD3C0.BFE334F0" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 18:34:02 -0500 ------ =_NextPart_000_01BAD3C0.BFE334F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable > >>>P.S. > >>>A, I the only one who remembers to CC Dave Levin on the address=20 >list? > >> > >>I've never received a (personal) notice from Dave, he just left me (u= s?)=20 > >>in the dark and I always had to hear from some others that they had=20 > >>made contact with him. The least he could have done was send a=20 > >>(general) note telling he had no time for the SD-project anymore. > >>In fact the only message I got from him was the one of December=20 >17th. > >>So in short, I'm a disappointed by Dave's performance. > > >You have a point. Certainly droping the Newsletter functions off line fo= r .. >what is it 2-3 months now? Doesn't speak well for his enthusiasm. Then= >again the participation has been kind of slight in general lately. Hmmm... Well, this is interesting, considering I thought I --have-- been keeping everyone up to date by occassionally sending out messages CCed to everyone on this private list. Of course, I only occassionally get these messages, and then only from Kelly (and sometimes Kevin). In fact, as I said earlier today, SunSITE is having some major malfunctio= ns. In the meantime, for the last month or two, I've been working at home on getting together a system whereby LIT would have it's own computer, and people here would get disk space, email accounts, etc. at LIT. If you are reading this message, please check my CC's and TO line - - if there's someone I've left out, it's because I haven't been included on any of their CC's... can someone forward my messages to them? It's interesting to note that I've been administrating four other web sites... one of them, ArchaeoSETI, has also recently been "disappointed" in my "performance". I would like everyone to remember that we are ALL volunteers in this endeavor... this includes me. LIT was meant from the first to be an entirely web-based campus. To be honest, I've never liked the idea of an email newsletter, and would have preferred some kind of web-based discussion system (and one a little more stable than the one I had originally written). However, since everyone seemed to think that email newsletters were the way to go, I've tried to keep up as best I could. All of the newsletters you have EVER received from LIT have been processed ONE AT A TIME by me with a simple filter... I couldn't even get ".forward" to work on SunSITE, so I had to feed each email into the filter program myself. Let me tell you, this is a bunch of work. Anyway, I have never ever intended to drop LIT, and I promise you I am working in almost all of my free time to rebuild LIT into what I've always wanted it to be. One of the ideas of LIT was that it would grow. I wanted it to be big. In this case, it was to have several people helping me run such things as classes and discussions. I can't do everything. When LIT returns, I will still need help. One of the things I'd like to do ASAP is find a charitable listserv that could perhaps support the discussion list. I have no idea where to start doing this. Does anyone have any ideas? RE: the last message from me being on Dec. 17th. Does anyone realize that it's the 26th today? In my book, nine days since my last message (and actually I sent something this very morning) is not exactly a very long time. Hell, the newsletters from LIT used to come out once a week, and were usually late at that. Is 9 days really an eternity all of the sudden? There is lots more I'd like to say, but I'll let it lie for now. -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD3C0.BFE334F0 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IgwXAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaABIA IgACAAIAMAEBCYABACEAAABGRDM2NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMABLBwEggAMA DgAAAMsHDAAaABIAIgALAAIAOQEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAGwAAAFJFOiBFbmdpbmVlcmluZyBOZXdzbGV0dGVyAKkJAQ2ABAACAAAAAgACAAEDkAYAYAwA ABIAAAALACMAAAAAAAsAKQAAAAAAAwAmAAAAAAADADYAAAAAAB4AcAABAAAAFwAAAEVuZ2luZWVy aW5nIE5ld3NsZXR0ZXIAAAIBcQABAAAAGwAAAAG60+hLRfZuNvc6vBHPrAgAgF8UovAAAAqeIQAD AAYQU5odMgMABxDmCgAAHgAIEAEAAABlAAAAUFNBLElUSEVPTkxZT05FV0hPUkVNRU1CRVJTVE9D Q0RBVkVMRVZJTk9OVEhFQUREUkVTU0xJU1Q/SVZFTkVWRVJSRUNFSVZFREEoUEVSU09OQUwpTk9U SUNFRlJPTURBVkUsSAAAAAADABAQBAAAAAMAERADAAAAAgEJEAEAAAC4CgAAtAoAADoVAABMWkZ1 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([nil nil nil nil nil nil nil nil nil] ["4261" "Tue" "26" "December" "1995" "18:38:52" "-0500" "David Levine" "David@interworld.com" nil "77" "RE: RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA29240 for ; Tue, 26 Dec 1995 15:34:22 -0800 (PST) Received: by www with Microsoft Mail id <01BAD3C1.687ECFC0@www>; Tue, 26 Dec 1995 18:38:54 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD3C1.6884EA40" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 18:38:52 -0500 ------ =_NextPart_000_01BAD3C1.6884EA40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Yes, SunSITE lost EVERYTHING. They're still trying to figure out with Sun what happened. Apparently, the last backup didn't even turn out to be a complete backup. And when they try restoring from an older backup, the machine keeps freezing up. They promise to have stuff back soon, but it might be a month old (which is not too bad for the Asimov, but really stinks for things like ArchaeoSETI, and a huge amount of stuff that others have on SunSITE). However, every few days they've been promising to have stuff back in a few days... so, I don't really know whether to believe things will be all right or not. Anyway, I have backups of various items, but not the entire site. The problem is that the site was very poorly organized, directory-wise, and several of my sites shared the same directory. The resulting mess was more megabytes than I cared to personally back up, trusting SunSITE's backup devices. You'd be surprised how big LIT alone was. Anyway, this is another reason I've been reorganizing stuff at home (this stuff I've saved) - - to give some sort of logical order to the structure, and make it easier to backup, etc. Never fear, LIT will return (and better than ever)... the question is whe= n. -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD3C1.6884EA40 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IjcXAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaABIA JgA0AAIAZgEBCYABACEAAAAwMTM3NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMAAjBwEggAMA DgAAAMsHDAAaABIAJgA2AAIAaAEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAHwAAAFJFOiBSRTogRW5naW5lZXJpbmcgTmV3c2xldHRlcgCaCgENgAQAAgAAAAIAAgABA5AG AKgGAAASAAAACwAjAAAAAAALACkAAAAAAAMAJgAAAAAAAwA2AAAAAAAeAHAAAQAAABsAAABSRTog RW5naW5lZXJpbmcgTmV3c2xldHRlcgAAAgFxAAEAAAAbAAAAAbrT6H6a9m42/Dq8Ec+sCACAXxSi 8AAAZ/myAAMABhC2td63AwAHEDUEAAAeAAgQAQAAAGUAAABZRVMsU1VOU0lURUxPU1RFVkVSWVRI SU5HVEhFWVJFU1RJTExUUllJTkdUT0ZJR1VSRU9VVFdJVEhTVU5XSEFUSEFQUEVORURBUFBBUkVO VExZLFRIRUxBU1RCQUNLVVBESUROAAAAAAMAEBAAAAAAAwAREAMAAAACAQkQAQAAAPwEAAD4BAAA DAgAAExaRnWXVusU/wAKAQ8CFQKoBesCgwBQAvIJAgBjaArAc2V0MjcGAAbDAoMyA8UCAHByQnER 4nN0ZW0CgzP3AuQHEwKDNANFEzUHbQKDtjUSzBTINgPGFMg3EsypD99mOBEMMRs+fQqAywjPCdk7 HzkxMhxgCjLHIREgWgoUMjU1AoAKgYMNsQtgbmcxMDMUUKcLChRRC/EgWQeQLAYAgHVuU0lURSAe 0AETwCBFVkVSWVRASElORy4gFkBo6GV5Jx9AIBPAAxADICh0cnkLgGcoEG8g6GZpZwhwZQqFCGAF QPkD8HRoJZIpwBGABUARgNxwcAnwCYAnEUEq0ArA8QnwdGx5JYAp8CegC2AFJkFiANBrdXAgZCBp ZG4ndAqFZXa/CfAoEAhwA6ApkiiRYieg9GEgBaBtC1ARwCegLLT5KzJuZCpRLhInUSgSCoV/H0AT wAWwKFIDUi8gLnFsbwSBLKUsBADBaAuAJ6Br3QngcAQgA1AJ4HooUjAh+wqFJ0IgE1ADcAQAJ6Ao kXcRgC4AJ7F1DdAsoyewb3sCICWAYimhKeA0ICjQaG8skS8SBGACMGgpJjMgIDooKmBpEXA40AQg bm97LrIu4WEwkAIQBcAsIkH7AJAEYHY4hB9AB0Ar4Cey/G5rNPEFsAqFKfAoUQQgHGxpNLAUsRFx ZW9TeEVUSSWAAHAwkC8waLx1Zy8RBGAlsAVAbzfQ/zeUKfAqgTtwJ1ARoAqFN0MbAiAllik1xgqF SG93XS3xciWARWIxMGYH0WT2YROwMPMnN2EvAC4RNpS/KFU3TQqFC4AvIUYmLkqAezgxJYBJLRAC IC1gPVZr/ztgB+AwsUKCLsQ/UC3xPtX/CoUD8CfxLwIn8QUQOTIFsfM7YTBDeXdGcEriN0MstOsE IEGRdgrAaQhgBCAp4H8T4CVwCoU4ojtjLDErsWn/J5JSEScUNoICYBPgOyJCI38sIlQSKcAscFGA ReEKhXAtOFByPaEFsGcAcGl6LwmAJYAtIB9AYzIheS19A/FlQFQRsEVxB0BBgm33PbFSEQQgcxGB CYA+dyehn0EgJ6BYZ1RVMfF1bD3h/yhwB4EEIFZSBGAnkQeAV9BsYnlaokIhbgqFSwBj/1sCKIIq 4BGgAiA9gzfzM7PuclHgXZMlpScEICy0CoVdDbB2OvAHkCcRWQhgJ3cwkC8BXWByE1A20TCQaOVM EWIo0CBMJeBOsQIg/1YzT8k+4VHxQsYAcEJzPVL/YPFK8Eb3H0BXtShSN5QqgvsDcCegKGfTN5Rp ogqFW/BhLgBkKSAtbcEogmf+aTdia7I4QAAgQYIe0G5Q/2AwWgELIEyUVcNiAVigKPH/QFMKhQDA P3E44WlBCJEuw/szhRHAY0RNB8BFcUYRCsDfJYBmUk5DH0AuQyhAci8AfwJATJJfcUWzRDBKkSwi cf8KUCfBQ5E7MTCyRE0K+xpS2jEZIGMN4G3ALQtGF5L7e3MAUGl56AtkFWEL8BKw83uhCiAgRDdQ LTBmQGQRvysAefUrYT9QYDB4s0UjsLc0cTNBbdBJAjAEkFdXYQ9bNn3PJTA5QHRwOi+0L3eEYC4L gHcRd4ISqi4vUS8TwGEN0C9GYH1/MS+Czx1Qgl9+Z30wSPc28QiBYHNrJ+JcESnTSeH9BbBrP1AB gEqBh40cYXtgFjdEth5hAI2wQAA5ANDhSlDr07oBAgFHAAEAAAA1AAAAYz1VUzthPSA7cD1JbnRl cldvcmxkO2w9UHJpdmF0ZSBNREItOTUxMjI2MjMzODUyWi00NAAAAABAAAcwcG5JUOvTugFAAAgw UKdlUevTugEeAD0AAQAAAAUAAABSRTogAAAAAAIBFDQBAAAAEAAAAFSUocApfxAbpYcIACsqJRdL Fw== ------ =_NextPart_000_01BAD3C1.6884EA40-- From popserver Tue Dec 26 23:38:21 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2177" "Tue" "26" "December" "1995" "18:40:42" "-0500" "David Levine" "David@interworld.com" nil "44" "RE: RE: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id PAA29339 for ; Tue, 26 Dec 1995 15:36:12 -0800 (PST) Received: by www with Microsoft Mail id <01BAD3C1.AA1E6EE0@www>; Tue, 26 Dec 1995 18:40:44 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD3C1.AA248960" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 18:40:42 -0500 ------ =_NextPart_000_01BAD3C1.AA248960 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Oh, as for my previous post - I do apologize - I've checked my archives and have also received some CCs from Steve and a few from Ric (plus one from Zenon). -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD3C1.AA248960 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+Ii0XAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaABIA KAAqAAIAXgEBCYABACEAAAAwNTM3NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMAAnBwEggAMA DgAAAMsHDAAaABIAKAAsAAIAYAEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAHwAAAFJFOiBSRTogRW5naW5lZXJpbmcgTmV3c2xldHRlcgCaCgENgAQAAgAAAAIAAgABA5AG AMADAAASAAAACwAjAAAAAAALACkAAAAAAAMAJgAAAAAAAwA2AAAAAAAeAHAAAQAAABsAAABSRTog RW5naW5lZXJpbmcgTmV3c2xldHRlcgAAAgFxAAEAAAAbAAAAAbrT6H6a9m42/Dq8Ec+sCACAXxSi 8AAAkwKzAAMABhAjM1BFAwAHEOYAAAAeAAgQAQAAAGUAAABPSCxBU0ZPUk1ZUFJFVklPVVNQT1NU LUlET0FQT0xPR0laRS1JVkVDSEVDS0VETVlBUkNISVZFU0FOREhBVkVBTFNPUkVDRUlWRURTT01F Q0NTRlJPTVNURVZFQU5EQUZFV0ZSAAAAAAMAEBAAAAAAAwAREAMAAAACAQkQAQAAABMCAAAPAgAA 1gMAAExaRnU1jbiQ/wAKAQ8CFQKoBesCgwBQAvIJAgBjaArAc2V0MjcGAAbDAoMyA8UCAHByQnER 4nN0ZW0CgzP3AuQHEwKDNANFEzUHbQKDtjUSzBTINgPGFMg3EsypD99mOBEMMRs+fQqAywjPCdk7 HzkxMhxgCjLHIREgWgoUMjU1AoAKgYMNsQtgbmcxMDMUUBcLChRRC/JjEqAgT2g4LCBhBCACEAXA bXliIBNQZXZpCGAEIHACbxPAIC0gSSBkDm8lwCcAHtBnaXpluSdCJ3YoQBFwBZBrCYDXJjIKwBFw aSigcwqFAHBvKTARgCihB0BzJ6AfQGMeZSnBKTArIAeAIENDvyXhA2EGABPQKtIqgWEl8KMH0Sxz UmljCoUoC1BvJtECIChALHNaCfACICmGLgqFCotsaTM2DfDrJHwTUG8T0GMFQAqPC5GdGlIxGSAl UDJ4LS0LRv8XkjSTAFAAoDKfC2QVYQvwrxKwNMIMMDb2RCrAaSkwzkwmkS8gMxVBcAtQLiDsYXQm sAOgRSOwOkEEkJcnQgIwBJBXBbBsZDd/CziHNvZoAkBwOi8vWnc/gC4LgDxxdzyyLikFoG0vE8Bh DdAvZH05wi89bwBQNv89jzbYSK0oQHQIgSkwdCegawMQZwMgLAED8HRoLVIFsGv7MVABgC5HkEMt HGE0gBpQC0KtHmEASlAAQAA5AAASA5Lr07oBAgFHAAEAAAA1AAAAYz1VUzthPSA7cD1JbnRlcldv cmxkO2w9UHJpdmF0ZSBNREItOTUxMjI2MjM0MDQyWi00NQAAAABAAAcwgPYkbOvTugFAAAgwsFIF k+vTugEeAD0AAQAAAAUAAABSRTogAAAAAAIBFDQBAAAAEAAAAFSUocApfxAbpYcIACsqJRcI/w== ------ =_NextPart_000_01BAD3C1.AA248960-- From popserver Wed Dec 27 01:05:49 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2448" "Tue" "26" "December" "1995" "20:06:54" "-0500" "David Levine" "David@interworld.com" nil "48" "RE: RE: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id RAA03521 for ; Tue, 26 Dec 1995 17:02:40 -0800 (PST) Received: by www with Microsoft Mail id <01BAD3CD.B831AE50@www>; Tue, 26 Dec 1995 20:07:01 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD3CD.B8394F70" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 20:06:54 -0500 ------ =_NextPart_000_01BAD3CD.B8394F70 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Okay, I've heard from SunSITE - it turns out the latest full backups they have are October 25, and they are just now starting to restore them. Bleah. They promise it won't happen again (and that we'll never lose more than a day's work in the future)... but, still.... Bleah. -- David Levine Application Engineer - InterWorld http://www.interworld.com/staff/david/ He tried to kill me with a forklift... ------ =_NextPart_000_01BAD3CD.B8394F70 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IgIBAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEFgAMADgAAAMsHDAAaABQA BgA2AAIASgEBCYABACEAAAAwRTM3NkVGNkJDM0FDRjExQUMwODAwODA1RjE0QTJGMAA3BwEggAMA DgAAAMsHDAAaABQABwABAAIAFgEBCIAHABgAAABJUE0uTWljcm9zb2Z0IE1haWwuTm90ZQAxCAEE gAEAHwAAAFJFOiBSRTogRW5naW5lZXJpbmcgTmV3c2xldHRlcgCaCgENgAQAAgAAAAIAAgABA5AG ADAEAAASAAAACwAjAAAAAAALACkAAAAAAAMAJgAAAAAAAwA2AAAAAAAeAHAAAQAAABsAAABSRTog RW5naW5lZXJpbmcgTmV3c2xldHRlcgAAAgFxAAEAAAAbAAAAAbrT6H6a9m42/Dq8Ec+sCACAXxSi 8AADlyPUAAMABhBIaKiIAwAHED4BAAAeAAgQAQAAAGUAAABPS0FZLElWRUhFQVJERlJPTVNVTlNJ VEUtSVRUVVJOU09VVFRIRUxBVEVTVEZVTExCQUNLVVBTVEhFWUhBVkVBUkVPQ1RPQkVSMjUsQU5E VEhFWUFSRUpVU1ROT1dTVEFSVElOAAAAAAMAEBAAAAAAAwAREAMAAAACAQkQAQAAAIECAAB9AgAA WwQAAExaRnVfwcud/wAKAQ8CFQKoBesCgwBQAvIJAgBjaArAc2V0MjcGAAbDAoMyA8UCAHByQnER 4nN0ZW0CgzP3AuQHEwKDNANFEzUHbQKDtjUSzBTINgPGFMg3EsypD99mOBEMMRs+fQqAywjPCdk7 HzkxMhxgCjLHIREgWgoUMjU1AoAKgYMNsQtgbmcxMDMUUBcLChRRC/JjEqAgT2sAYXksIEkndmVo IGhlCxEgA1IGAHUAblNJVEUgLSD6aQVAdAhwBjEIYCehJkAeIAtgE9ATwCaQdWxsxQqFYgDQa3Vw BCAoYTp5JjBhJhEKwCYgT2PodG9iBJAgIuAl0ABwJyaAKkMq4mp1KOFub653CoUTwArAdAuAZyew fG8gH0ATwAWwJiAoYW2gLiAgQmwmUGgvIX5UKlITUANwBAAmICeRd5kCICd0CoURgHBwCfDlKtBn C3EgKCvkKLAwwOxlJykwLPBlJhAFwB7QjzBxBGAuswORYSBkJbDMJ3MKhTDQcmsngAOgxyhiKRAn wWUpLjbAKbDvKDAl0BPAAxBsNsEvJwqF4QqLbGkzNg3wJHwwId8T0CswOMwLVRpSMRkgJVD5Osgt LQtGF5I84wBQAKD/Ou8LZBVhC/ASsD0SDDA/RmpEKqBpJoBMM3ALgGWtO2VBMbA5oGMosGkCILwg RSOwQpErcSdwSQIw5QSQVwWwbGQ/z0DXP0aCaAJAcDovL3dH0F4uC4BEwTWRRSAuBaBtti8toQ3Q LzTQQiEvRb/vAFA/T0XfPyhILsEIgSwB/S5AazdxNAAmIAPwKGA0of8CEDWwOaABgDbBS30cYTzQ FxpQSv0eYQBSoAAAAEAAOQBwtcSc99O6AQIBRwABAAAANQAAAGM9VVM7YT0gO3A9SW50ZXJXb3Js ZDtsPVByaXZhdGUgTURCLTk1MTIyNzAxMDY1NVotNDYAAAAAQAAHMMASvZz307oBQAAIMHAKF6H3 07oBHgA9AAEAAAAFAAAAUkU6IAAAAAACARQ0AQAAABAAAABUlKHAKX8QG6WHCAArKiUXgC8= ------ =_NextPart_000_01BAD3CD.B8394F70-- From popserver Wed Dec 27 18:01:26 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2712" "Wed" "27" "December" "1995" "15:39:05" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "62" "Re: David" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id GAA27111 for ; Wed, 27 Dec 1995 06:37:57 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10767 (5.67b/IDA-1.5 for ); Wed, 27 Dec 1995 15:38:57 +0100 Message-Id: <199512271438.AA10767@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: David Date: Wed, 27 Dec 1995 15:39:05 +0100 Hello David, >It's interesting to note that I've been administrating four other web >sites... one of them, ArchaeoSETI, has also recently been >"disappointed" in my "performance". I would like everyone to remember >that we are ALL volunteers in this endeavor... this includes me. True, but I still don't know why your support for SD stopped the way it did. >LIT was meant from the first to be an entirely web-based campus. >To be honest, I've never liked the idea of an email newsletter, and >would have preferred some kind of web-based discussion system >(and one a little more stable than the one I had originally written). I like the idea of a discussion system, in fact that is what we are doing for the last 2 months. At the time I didn't vote on this because I did not participate that much. A "subscribe" list would probably be very handy. >One of the ideas of LIT was that it would grow. I wanted it to be big. >In this case, it was to have several people helping me run such things >as classes and discussions. I can't do everything. When LIT >returns, I will still need help. On of my reasons for disappointment was that some long time ago I offered you some help by writing some documents and a program. You replied to me that at that time you had no time and would write back. After waiting a few weeks I send a similar letter once more. Again you replied the same. But I'm still waiting for an answer. My offer still stands... >One of the things I'd like to do ASAP is find a charitable listserv >that could perhaps support the discussion list. I have no idea where >to start doing this. Does anyone have any ideas? As far as I know this can be done at any server with form-capabilities, the thing you need to install is a auto-mailer. (I tried to do it once but got not very far.) >RE: the last message from me being on Dec. 17th. Does anyone realize >that it's the 26th today? In my book, nine days since my last message >(and actually I sent something this very morning) is not exactly >a very long time. Hell, the newsletters from LIT used to come out >once a week, and were usually late at that. Is 9 days really an >eternity all of the sudden? That message of Dec. 17th was the last and the ONLY letter I received from you, the only other trace I have found was at Nov. 10th where Kevin told that you had written him. As I wrote before I can understand that you are busy, but I can't understand that you have not 15 minutes to write a letter to people that try to build something together with you. > >Attachment Converted: D:\REEngin1 > What is this attachment? All letters from you seem to include it, but when I take a look at it, it is garbled completely. Timothy From popserver Wed Dec 27 18:01:28 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5100" "Wed" "27" "December" "1995" "15:39:12" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "95" "Re: Kelly" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id GAA27117 for ; Wed, 27 Dec 1995 06:38:06 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10773 (5.67b/IDA-1.5 for ); Wed, 27 Dec 1995 15:39:06 +0100 Message-Id: <199512271439.AA10773@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Kelly Date: Wed, 27 Dec 1995 15:39:12 +0100 Timothy replies to Kelly > >>After rethinking it, I see what you mean. > >>The only thing I'm not sure about is what the physics of plasma reflection > >>are. We may reflect radio-waves to the ionosphere everyday but how does it > >>work? And does it work in the Asimov also? > >It would certainly involve a much larger scale, and I don't know what the >reflection efficency is. Or how much mass would need to be ionized to keep >up the reflection. One thing for certain, the stuff will be HOT! I think it is that HOT thing that worries me, it may well be that that will screw up your whole nice reflection. >That would be true if all major areas of research were being investigated and >resonably well funded. But most areas of fusion research that I know of have >no funding. Magnetic plasma fusion is geting funded, but at least in the US >the systems are dead ends. Even if they worked they'ld be useless (to large >to be intergrated into the power grid.). Where as more inovative designs >that are considered more promising (like Bussards among others) are geting no >funding. You can't assume that more money is used for this, because I could assume that more money is used for research for anti-matter containment and creation. Both fusion and anti-matter are areas where little is known about. >Oh yeah, the single stage to orbit program (SSTO). My excorperation, and the >NASA department I used to work at in NASA headquarters were working on that >program. Increadable potential. It could cut costs to orbit by a factor of >100! Fed Ex is even rumored to be seriously interested in using them for >suborbital intercontenental mail carriers. E-mail is cheaper and faster :) >I'ld debate that. Since your stuck in an artificial habitat anyway, one in >space has easy access to all the floating ores and raw materials in the solar >system. Much of which would be hard to get at on a planet (ever see a strip >mine) and much harder to transport. I'm a firm beleaver that heavy industry >will largely move off earth in a century or two. If your already off planet >and in a starship, trying to set up on a planet would be hellish. Hmm, yeps, you may well be right. But the place where people want to live will be on a nice planet. Doing research on a planet or building industries is still much more interesting than flying back to Earth. And if it isn't more intersting, then research will gives more fruits for the money than flying back would do. >People won't see it right away, but they will know people are out there. I >think that would be enough to get public interest. I know public interest in >robot probes is near nill. As NASA constantly found. Robots were thought of >as scout craft for maned expiditions. If no manned folowups were planed (and >frequently mentioned) public interest in funding the robots droped way off. > Generally a so what atitude. Drove the Robot probe teams CRAZY! I think that the mission will not be funded by governments but by commercial firms. They would use it as advertisement and gain of new technology. Such a project will not be done by one country, but by all developped countries. So the competition between countries would not be the same as they were in past times. So public interest should have a completely other background: love for the unknown. Ordinary people probably are more concerned about other things. > >>So where to and when is our new goal? Until now only fusion may bring > >>us out of the solar system within reasonable time. Even if you use a > >>beam, the fusion is necessary to maintain the beam. > >Well you could power the beam with big solar electric power platforms in >space. (The kind of stuff the L-5 socyety kept proposing to power earth.) No, Earth's consumption of electricity is much much less than that of the Asimov. As I showed before you would need an array bigger than the moon! And than you only have the energy but not the beam. For that you need again an enormous array of high power masers. >I would definatly prefer a dead world as a possible colony site over a lush >one like earth. Wouldn't be as interesting to study, but much more >survivable. The problem is any world that could support us, probably has >life. So how do we solve that? Walking in spacesuits all day isn't that much fun. >Hell, we're still trying to find cures for all the plagues on earth. So far >our best luck seem to be in destroying the worst sections of the ecology >(draining wetlands, fogging everything with pestasides, etc..) and building >urban semi-ecologies. Most of the habited areas of the developed world >(europe, North America, etc..) do this so routinely we don't even notice >anymore. But then living in a coutry thats largly under sea level I hardly >have to tell you. ;) The place I live is save, even if all the polar ice melts away. :) (33 metres above sealevel) What you write may be true, but is not complete, we have found cures for many diseases and our understanding gets better all the time. In 50 years this will only be better and more advanced. Timothy From popserver Wed Dec 27 18:01:31 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2790" "Wed" "27" "December" "1995" "15:39:21" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "53" "Re: Kevin" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id GAA27122 for ; Wed, 27 Dec 1995 06:38:14 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10782 (5.67b/IDA-1.5 for ); Wed, 27 Dec 1995 15:39:15 +0100 Message-Id: <199512271439.AA10782@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Kevin Date: Wed, 27 Dec 1995 15:39:21 +0100 ReplyTo: Kevin Subject: Bio interaction between earth and E.T. organisms. >this is not to say that a alien ecosystem would be totally useless to >us. who know what wonders we may find. how bout an organism that can >"grow" silicon chips? of solar cells? perhaps some organism lives in a >metal rich environment and can really concentrate metal ores. Perhaps, >perhaps, perhaps. I could go on all day, how bout a critter that _likes_ >70 % ethanol (I'll bet that many companies would love to make brandy >without having to distill) bacteria that excrete oil, or plastic, or ones >that prefer it as a food source. the list goes on and on, and I'm very >willing to bet that none of these creatures will be the first exploitable >alien lifeform. and I'd further bet that the universe is not only >stranger than I imagined, it's stranger than i _can_ imagine. It seems that some of that kind of bacteria also live on earth, every week new ones are discovered. Solar cells are a bit to complex to be produced by bacteria and I think they won't produce pure silicium bars either. So maybe you imagined a bit too much. What bacteria are best at is converting molecules (not atoms). But you shouldn't forget that we are getting better and better in doing the same thing with technology. >In short, A totally barren 1 G planent would be ideal for colonization, >but totally boring for study. That means we need two planets :) Subject: mission >I think perhaps it's time to either put the "Asimov" on a diet, or >approach the problem from the other end. To put the "Asimov" on a diet, >I'd suggest at least a thousand fold reduction in payload down to 1E+05 Kg >I think this rules out self sustained mission, and requires a return. I >still think we can go at 1 G, and use a MARS for the engine, but in order >to over come the photon thrust, we're going to have to bring more >reaction mass ( and use a slower exhaust velocity). for the return trip, >I'd suggest scrapping the lineac entirely, and relying on photonic thrust >for both portions of the trip. this means that some payload capacity >will have to be devoted to maser transmitter control packages, but i >don't see this as a real problem. the crew should be pared down to no >more than 100 people, and the return module can totaly scrap the hab ring >which can then be left in the target system as a stepping stone for a >follow up crew if one is deemed desirable As Kelly said, 1E5 is too small, probably the engines alone would weigh that much. Also such "maser transmitter control packages" as you call them so neatly won't be thato small, you are talking about an array of several square kilometres filled with masers and powerstations. (See also my letter to Kelly at Dec. 23th) Timothy From popserver Wed Dec 27 18:01:46 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["11958" "Wed" "27" "December" "1995" "10:30:27" "-0500" "David Levine" "David@interworld.com" nil "214" "RE: David" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: David@InterWorld.com Received: from www (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id HAA28461 for ; Wed, 27 Dec 1995 07:25:59 -0800 (PST) Received: by www with Microsoft Mail id <01BAD446.5C2BE610@www>; Wed, 27 Dec 1995 10:30:36 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BAD446.5C45D6B0" From: David Levine To: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "KellySt@aol.com" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" To: "'Timothy van der Linden'" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: David Date: Wed, 27 Dec 1995 10:30:27 -0500 ------ =_NextPart_000_01BAD446.5C45D6B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit >True, but I still don't know why your support for SD stopped the way it >did. As I've said, I don't really think my support has ever stopped. The newsletters fell apart at my end, mainly because the file containing the email addresses got corrupted. Yes, it could have been rebuilt, but there were absolutely hundreds of people involved... Anyway, I certainly had never intended (and still don't intend) that the official newsletters are dead. It WILL return. >>LIT was meant from the first to be an entirely web-based campus. >>To be honest, I've never liked the idea of an email newsletter, and >>would have preferred some kind of web-based discussion system >>(and one a little more stable than the one I had originally written). > >I like the idea of a discussion system, in fact that is what we are doing >for the last 2 months. At the time I didn't vote on this because I did not >participate that much. A "subscribe" list would probably be very handy. Actually, perhaps I didn't explain myself well... when I say a "web-based discussion system" I mean one that works entirely though the WWW, and does not include email in any way. You would post using forms, and read the discussion on a series of pages. However, I think the majority of the most active people seem to prefer an email discussion list. >On of my reasons for disappointment was that some long time ago I >offered >you some help by writing some documents and a program. You replied >to me >that at that time you had no time and would write back. After waiting a >few >weeks I send a similar letter once more. Again you replied the same. But >I'm >still waiting for an answer. >My offer still stands... Just so you know, my response right now to such an offer would be "please, go ahead, write something and let me know when you have finished". This is how I responded to several people who wished to write articles for LIT (i.e. Ges Seger, Jack Sarfatti come to mind... there are a few others who have contributed that I can't remember off-hand at the moment) in the past... If you made an offer to which I said "I don't have the time at the moment" in response, I can only assume that your offer was not of the "I have an idea for an article I'd like to write" variety, but rather a "what can I do to help?" offer.... my response to the latter would STILL be "I'll have to get back to you, I don't have the time right now", mainly because I don't have the time to figure out who should be writing what, when, and how. I always accept anything you'd want to put on the pages. When SunSITE gets its act together again, I'll do a quick survey for you, and I think you'll find that at least a third of the starship school pages are not by me... and ALL of them were pages people just sent me, saying "here, can you use this?" So, please, if you want to do something (and this is to everyone), please do it. When LIT is back, it can continue to grow in the way it has in the past. >>One of the things I'd like to do ASAP is find a charitable listserv >>that could perhaps support the discussion list. I have no idea where >>to start doing this. Does anyone have any ideas? > >As far as I know this can be done at any server with form-capabilities, the >thing you need to install is a auto-mailer. (I tried to do it once but got >not very far.) I think we're talking at cross-purposes again. I'm looking for a listserv at some site somewhere that is charitable enough to start a new discussion list (I have heard that many listservs will do this - I just don't know how to go about doing it) for us... it would make things very simple, and very automatic. >That message of Dec. 17th was the last and the ONLY letter I received >from >you, the only other trace I have found was at Nov. 10th where Kevin told >that you had written him. > >As I wrote before I can understand that you are busy, but I can't >understand >that you have not 15 minutes to write a letter to people that try to build >something together with you. Um, I've looked through my archive of the current batch of "newsletters", extending back to November 5th (again, a majority of these come from Kelly), and find... um... let's see... zero from Tim, out of fifty nine messages since then. When I respond to this list (and granted it's not often... but to be honest, most of this discussion is out of my technical depth, and I've rarely participated in the project since it's beginnings over a year ago anyway, even when it was five newsletters once a week) it's reply-to-all.... if you're not getting them, I can only assume you're not getting the letters I'm responding to anyway. Actually, I have a bad feeling now that apparently with my 59 messages, I'm still missing quite a number. Sigh. >> >>Attachment Converted: D:\REEngin1 >> > >What is this attachment? All letters from you seem to include it, but >when I >take a look at it, it is garbled completely. > >Timothy On this front, I'm sorry, I don't know. Certainly I'm not attaching anything to my documents. We're using Microsoft Exchange at work, which every time it starts reminds me its a Beta, sooooo.... Also, some people tell me that some of my letters include odd characters (=20, or something) at the end of each line... Also something I don't see when I'm typing messages. 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NAA21077 for ; Wed, 27 Dec 1995 13:41:42 -0800 (PST) Received: from sea-ts3-p47.wolfenet.com (sea-ts3-p47.wolfenet.com [204.157.98.229]) by wolfe.net (8.7.3/8.7) with SMTP id NAA08002; Wed, 27 Dec 1995 13:43:13 -0800 (PST) Message-Id: <199512272143.NAA08002@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl Subject: Re: Engineering Newsletter Date: Wed, 27 Dec 1995 13:43:13 -0800 (PST) >ReplyTo : Ric > >>In system travel should give us a good idea of how well people adapt to >>space travel. A few missions of longer and longer duration to near and then >>farther planets would help to see the adaptiveness of humans to prolonged >>space flight. By the time we sent some folks to Titan and back we could >>refine the problem and work on means to sidestep these. > >Yes, that will give us a preview. But I think you don't have to wait for >that: Imagine living and working in your own house, never allowed to open >the door and go outside. When looking outside nothing happens, the stars >almost don't change. How would you feel? >How many people are there that can survive happely and healty in such an >environment? >Probably an important feature of the spacevessel would be that it feeled >much like Earth's environment. This doesn't mean it should look the same, >but several things like a leisure room, a bar, a garden of some sort (and >maybe a swimming pool) also crew quarters should not be too small. In fact >all kinds of things that would make the spaceship bigger and heavier would >make living better. >So the dilemmas are size and weight versus crew happyness and healthyness. >The point is to make a spacevessel that feels like YOUR environment (home, >work, shops). Ric replies: This is about like what I was saying many, many months ago. It wouldn't be much different than life in a submarine. The spaces would be larger. The number of people would be many more. There would be windows where as a submarine doesn't. The only limiting factor for subs is the food issue. ( Take it with us or grow it along the way, eother one ) Humans are a pretty addaptable animal. Look at how many different localities they inhabit on this earth. The room to move about and jobs to do and time and places to relax are importent to the mission. The Mir and Space Shuttle are OK for short periods of time. For years and years you can't have enough space and room. Hab modules with different "landscapes" and " cultures" would help relieve boredom. >>We are going to have to establish a solarsystem based society before we >>would be able to convince anyone of the need to go anywhere else. > >So if we want to continue the SD project we should make it 2140 instead of 2040. Very possibly The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Wed Dec 27 21:52:50 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["671" "Wed" "27" "December" "1995" "13:54:05" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "19" "Re: possible LIT site." "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.2/8.7.2) with ESMTP id NAA21435 for ; Wed, 27 Dec 1995 13:47:40 -0800 (PST) Received: from sea-ts3-p47.wolfenet.com (sea-ts3-p47.wolfenet.com [204.157.98.229]) by wolfe.net (8.7.3/8.7) with SMTP id NAA08533; Wed, 27 Dec 1995 13:54:05 -0800 (PST) Message-Id: <199512272154.NAA08533@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: Kevin C Houston Cc: "David Levine \"jim@bogie2.bio.purdue.edu\"" , "'KellySt@aol.com'" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: Re: possible LIT site. Date: Wed, 27 Dec 1995 13:54:05 -0800 (PST) I would be willing to part with $20.00 (US) per year to see this >continue. >I've seen quotes in various magazines from $30 (US) for 10 MB on up. I >would think that for as little as $100 a year, we could have a very nice >website with lots and lots of room. Counting heads that i see here >often, (no pressure, I'm just thinking out loud) me, Dave, Kelly, Ric, >Timothy, Steve. That's 6 people who contribute regularly, would bring >the price down to $16.67 each. the more people who help, the less each >of us would have to pay. Count me in for a $20.00 bill. The rest of you all in?? Ric The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Wed Dec 27 22:03:11 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3987" "Wed" "27" "December" "1995" "23:02:01" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "71" "RE: David" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.2/8.7.2) with SMTP id OAA22119 for ; Wed, 27 Dec 1995 14:01:07 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA21112 (5.67b/IDA-1.5 for ); Wed, 27 Dec 1995 23:01:56 +0100 Message-Id: <199512272201.AA21112@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: RE: David Date: Wed, 27 Dec 1995 23:02:01 +0100 ReplyTo: David >>I like the idea of a discussion system, in fact that is what we are doing >>for the last 2 months. At the time I didn't vote on this because I did not >>participate that much. A "subscribe" list would probably be very handy. > >Actually, perhaps I didn't explain myself well... when I say a "web-based >discussion system" I mean one that works entirely though the WWW, and >does not include email in any way. You would post using forms, and >read the discussion on a series of pages. However, I think the majority >of the most active people seem to prefer an email discussion list. What is the real difference? If you have a mail-adress, you can forward all mail to a single file. (maybe change the filename every week) That file could be made visible in a web page. This of course is the most crude method, but it will work. (this way all mail-headers are included of course) Having to fill out forms takes a while, even if you copy it directly from a pre-written text into the form. For people with limited (dialup) access it is much more handy to send a single mail. Also downloading several pages is less convenient than just getting your mail. >Just so you know, my response right now to such an offer would be >"please, go ahead, write something and let me know when you have >finished". This is how I responded to several people who wished to >write articles for LIT (i.e. Ges Seger, Jack Sarfatti come to mind... >there are a few others who have contributed that I can't remember >off-hand at the moment) in the past... If you made an offer to which >I said "I don't have the time at the moment" in response, I can >only assume that your offer was not of the "I have an idea for an >article I'd like to write" variety, but rather a "what can I do to help?" >offer.... my response to the latter would STILL be "I'll have to get >back to you, I don't have the time right now", mainly because I >don't have the time to figure out who should be writing what, when, >and how. I always accept anything you'd want to put on the pages. >When SunSITE gets its act together again, I'll do a quick survey >for you, and I think you'll find that at least a third of the starship >school pages are not by me... and ALL of them were pages people >just sent me, saying "here, can you use this?" So, please, if >you want to do something (and this is to everyone), please do it. >When LIT is back, it can continue to grow in the way it has in the >past. In fact you had already some subjects (shown on some webpage), I asked you if you could tell me what the exact purpose was, because some of the subjects were quite broad. It would have been better if you had responded: "Just write, and I will put it on the web" instead you indeed wrote "I'll have to get back to you, I don't have the time right now". Also I said I had a Pascal-program that could do some calculations, I don't know what your answer was, but it wasn't "send it to me". >>As I wrote before I can understand that you are busy, but I can't >>understand >>that you have not 15 minutes to write a letter to people that try to build >>something together with you. > >Um, I've looked through my archive of the current batch of "newsletters", >extending back to November 5th (again, a majority of these come from >Kelly), and find... um... let's see... zero from Tim, out of fifty nine >messages since then. When I respond to this list (and granted it's >not often... but to be honest, most of this discussion is out of my >technical depth, and I've rarely participated in the project since it's >beginnings over a year ago anyway, even when it was five newsletters >once a week) it's reply-to-all.... if you're not getting them, I can only >assume you're not getting the letters I'm responding to anyway. >Actually, I have a bad feeling now that apparently with my 59 messages, >I'm still missing quite a number. Sigh. There are about 140 of them, I have all letters since contact was "lost". Timothy From popserver Sat Dec 30 04:58:29 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8226" "Fri" "29" "December" "1995" "21:53:43" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "201" "Re: RE: Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from mail06.mail.aol.com (mail06.mail.aol.com [152.163.172.108]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id SAA05669 for ; Fri, 29 Dec 1995 18:53:45 -0800 (PST) Received: by mail06.mail.aol.com (8.6.12/8.6.12) id VAA29778; Fri, 29 Dec 1995 21:53:43 -0500 Message-ID: <951229215342_80862787@mail06.mail.aol.com> From: KellySt@aol.com To: David@interworld.com, hous0042@maroon.tc.umn.edu, jim@bogie2.bio.purdue.edu, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, zkulpa@zmit1.ippt.gov.pl Subject: Re: RE: Engineering Newsletter Date: Fri, 29 Dec 1995 21:53:43 -0500 Sunsite didn't have a good backup since OCTOBER!! I'm glad were not paying them, at least were getting our moneys worth out of them. Dave, whats ArchaeoSETI? RE: Timothy replies to Kelly > > > >>After rethinking it, I see what you mean. > > >>The only thing I'm not sure about is what the physics of plasma reflection > > >>are. We may reflect radio-waves to the ionosphere everyday but how does it > > >>work? And does it work in the Asimov also? > > > >It would certainly involve a much larger scale, and I don't know what the > >reflection efficency is. Or how much mass would need to be ionized to keep > >up the reflection. One thing for certain, the stuff will be HOT! > > I think it is that HOT thing that worries me, it may well be that that > will screw up your whole nice reflection. Hot would be good for the reflection. It would meen it was more ionized. Also it would be more presure for drive purposes. Might be a little hard on the hull thou. ;) > >That would be true if all major areas of research were being investigated and > >resonably well funded. But most areas of fusion research that I know of have > >no funding. Magnetic plasma fusion is geting funded, but at least in the US > >the systems are dead ends. Even if they worked they'ld be useless (to large > >to be intergrated into the power grid.). Where as more inovative designs > >that are considered more promising (like Bussards among others) are geting no > >funding. > > You can't assume that more money is used for this, because I could assume > that more money is used for research for anti-matter containment and > creation. Both fusion and anti-matter are areas where little is known about. I wasn't refering to LIT assumptions, only real world. But, if we are to assume a large scale space infastructure. I guess we can assume it was worth there while to develope fusion systems. > >Oh yeah, the single stage to orbit program (SSTO). My excorperation, and the > >NASA department I used to work at in NASA headquarters were working on that > >program. Increadable potential. It could cut costs to orbit by a factor of > >100! Fed Ex is even rumored to be seriously interested in using them for > >suborbital intercontenental mail carriers. > > E-mail is cheaper and faster :) A but its so hard to E-mail a xmas present! ;) > >I'ld debate that. Since your stuck in an artificial habitat anyway, one in > >space has easy access to all the floating ores and raw materials in the solar > >system. Much of which would be hard to get at on a planet (ever see a strip > >mine) and much harder to transport. I'm a firm beleaver that heavy industry > >will largely move off earth in a century or two. If your already off planet > >and in a starship, trying to set up on a planet would be hellish. > > Hmm, yeps, you may well be right. But the place where people want to live > will be on a nice planet. Hey, if they want a nice planet their going to be out of luck on out flight. We'll only be ofering dead, or plague worlds. > Doing research on a planet or building industries is still much more > interesting than flying back to Earth. And if it isn't more intersting, then > research will gives more fruits for the money than flying back would do. Building industries? I don't follow. Research I can understand, but obviously they can't do that forever. Nor do I expect to settle for living out the rest of their lives in the hab deck. > >People won't see it right away, but they will know people are out there. > > I think that would be enough to get public interest. I know public interest in > >robot probes is near nill. As NASA constantly found. Robots were thought of > >as scout craft for maned expiditions. If no manned folowups were planed (and > >frequently mentioned) public interest in funding the robots droped way off. > > Generally a so what atitude. Drove the Robot probe teams CRAZY! > > I think that the mission will not be funded by governments but by commercial > firms. They would use it as advertisement and gain of new technology. Such a > project will not be done by one country, but by all developped countries. So > the competition between countries would not be the same as they were in past > times. So public interest should have a completely other background: love > for the unknown. Ordinary people probably are more concerned about other things. I can't see corporations droping probably hundreds of billions of dollars on a project like this. It absolutly would have no short term benifit (decades at least) and advertizing would supply this kind of money. International projects ARE A DISSASTER!! I was in the International Space Station Freedom Program, and can assure you it convinced about everybody that international cost everyone far more, slowed the program WAY down, and generally made it impossible. If a project like this requirers international particip[ation, it will be a write off. > > > >>So where to and when is our new goal? Until now only fusion may bring > > >>us out of the solar system within reasonable time. Even if you use a > > >>beam, the fusion is necessary to maintain the beam. > > > >Well you could power the beam with big solar electric power platforms in > >space. (The kind of stuff the L-5 socyety kept proposing to power earth.) > > No, Earth's consumption of electricity is much much less than that of the > Asimov. As I showed before you would need an array bigger than the moon! And > than you only have the energy but not the beam. For that you need again an > enormous array of high power masers. I don't remember you mentioning that. In any event its the cost not the size that would make a difference. > > >I would definatly prefer a dead world as a possible colony site over a lush > >one like earth. Wouldn't be as interesting to study, but much more > >survivable. The problem is any world that could support us, probably has > >life. > > So how do we solve that? Walking in spacesuits all day isn't that much fun. Exploration is seldom a lot of fun. I can't think of anyway to solve the biohazard problem other than space suits, or staying in the ship and using tele-operated robots. > >Hell, we're still trying to find cures for all the plagues on earth. So far > >our best luck seem to be in destroying the worst sections of the ecology > >(draining wetlands, fogging everything with pestasides, etc..) and building > >urban semi-ecologies. Most of the habited areas of the developed world > >(europe, North America, etc..) do this so routinely we don't even notice > >anymore. But then living in a coutry thats largly under sea level I hardly > >have to tell you. ;) > > The place I live is save, even if all the polar ice melts away. :) (33 > metres above sealevel) > What you write may be true, but is not complete, we have found cures for > many diseases and our understanding gets better all the time. In 50 years > this will only be better and more advanced. True, but its taken us centuries to get this far in our medical skills. We won't have centuries, or even decades, to learn how to fight the alien bio-hazards. > >ReplyTo : Ric > >>We are going to have to establish a solarsystem based society before > >>we would be able to convince anyone of the need to go anywhere else. > > > >So if we want to continue the SD project we should make it 2140 instead of > 2040. > > Very possibly > If we shove the calendar to 2140 from 2050, we'ld have nothing to base it on. We would have to debate what type of physics, much less engineering we could assume. Oh, what did.. whoever said it (I never got the origional message) mean by: > >>We are going to have to establish a solarsystem based society before > >>we would be able to convince anyone of the need to go anywhere else. We obviously arn't going to NEED to go to another star system, and certainly we've never come up with a reason anyone would want to stay in this other starsystem. (Trade obviously isn't practical with the technology we're discusing.) But that doesn't meen people wouldn't be interested in finding out what is there. Kelly P.S. I suppose I'ld kick in $20 for the cause if it would help. From popserver Sun Dec 31 01:59:18 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6198" "Sat" "30" "December" "1995" "22:07:00" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "130" "Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id NAA07583 for ; Sat, 30 Dec 1995 13:05:55 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA16549 (5.67b/IDA-1.5 for ); Sat, 30 Dec 1995 22:06:56 +0100 Message-Id: <199512302106.AA16549@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Engineering Newsletter Date: Sat, 30 Dec 1995 22:07:00 +0100 Timothy replies to Kelly: >>You can't assume that more money is used for this, because I could assume >>that more money is used for research for anti-matter containment and >>creation. Both fusion and anti-matter are areas where little is known >>about. > >I wasn't refering to LIT assumptions, only real world. But, if we are to >assume a large scale space infastructure. I guess we can assume it was worth >there while to develope fusion systems. Indeed, but so would anti-matter systems after a while. >>Doing research on a planet or building industries is still much more >>interesting than flying back to Earth. And if it isn't more intersting, then >>research will gives more fruits for the money than flying back would do. > >Building industries? I don't follow. For some kind of colonization. Even if it is used as "refresh" point for futere missions to other solarsystems, it needs some form of selfsufficiency. Therefor it needs "farms" and buildings, you can't make them all by hand, so you need some form of small industry. >Research I can understand, but obviously they can't do that forever. Why not, there will be plenty to figure out. >Nor do I expect to settle for living out the rest of their lives in the hab >deck. Why don't you expect them to do that? I still don't see that as suicide, they can live perfectly healthy lives. >I can't see corporations droping probably hundreds of billions of dollars on >a project like this. It absolutly would have no short term benifit (decades >at least) and advertizing would supply this kind of money. One Japanese building company is seriously thinking about how it could build on the moon. Now it may be a sign of advancement(=adverticement) but in 20 years they may be the first(=money) to build there. Indeed one company would not have enough money, but one company alone could not build a city, so several companies will take their share. And after all, the government's money is in fact the money of the companies. >International projects ARE A DISSASTER!! I was in the International Space >Station Freedom Program, and can assure you it convinced about everybody that >international cost everyone far more, slowed the program WAY down, and >generally made it impossible. If a project like this requirers international >particip[ation, it will be a write off. May be, but a single country couldn't do it either. I don't know all about problems about Freedom, but wasn't NASA the main "sponsor"? Such a project would be a challenge for mankind, it would not ALLOW us to work together, it would INSIST us working together. Maybe today such a project will not work, but countries are aligning. I know this sound biblical: "When all sheep listen to one herdsman...", but I think it's better than that: "The sum of the parts is much more than the parts themselves". >>No, Earth's consumption of electricity is much much less than that of the >>Asimov. As I showed before you would need an array bigger than the moon! >>And than you only have the energy but not the beam. For that you need again >>an enormous array of high power masers. > >I don't remember you mentioning that. In any event its the cost not the size >that would make a difference. Size is a problem of feasability. If things get too big, it takes also more time to build them. An array of thousands or even a million square kilometres is not possible to build in a reasonable time. >> So how do we solve that? Walking in spacesuits all day isn't that much fun. > >Exploration is seldom a lot of fun. I can't think of anyway to solve the >biohazard problem other than space suits, or staying in the ship and using >tele-operated robots. Exploration isn't much fun? What else drives people to such far places... >> The place I live is save, even if all the polar ice melts away. :) (33 >> metres above sealevel) >> What you write may be true, but is not complete, we have found cures for >> many diseases and our understanding gets better all the time. In 50 years >> this will only be better and more advanced. > >True, but its taken us centuries to get this far in our medical skills. We >won't have centuries, or even decades, to learn how to fight the alien >bio-hazards. In all these centuries we accumulated these skills, a lot of these skills can be used as general solutions and not as specific solutions. Often if a cure for one disease is found, a lot of similar diseases are cured too. It is not the specific case that takes decades to develop but the general solution. So since we want to know what is out there, we will study those creatures that have the potential to make us ill. Probably that is enough to find a specific cure. >>>So if we want to continue the SD project we should make it 2140 instead of >>>2040. >> >> Very possibly > >If we shove the calendar to 2140 from 2050, we'ld have nothing to base it on. > We would have to debate what type of physics, much less engineering we could >assume. So, what should we do? The main problem is the source of power that we are allowed to use. So before we start discussing how the engine looks, we should know what techniques we can use and in what AMOUNT. Just saying that money doesn't matter isn't enough, money means manpower. Whatever the futere will bring, the amount of capable manpower will be limited. >We obviously arn't going to NEED to go to another star system, and certainly >we've never come up with a reason anyone would want to stay in this other >starsystem. (Trade obviously isn't practical with the technology we're >discusing.) But that doesn't meen people wouldn't be interested in finding >out what is there. It could be a goal for better survival of the human species. Two so separate worlds are unlikely to become extinct at the same time. The reason for people to stay in such a desolated area is quite obvious, to start a new or other life. Think of the people that went to Australia the last 50 years (not the prisoners), a lot of them wanted new chances. Chances they could not realize at their previous home. My guess is that there are millions of people that want to get away from their present life and start somewhere else. Timothy From popserver Sun Dec 31 11:43:39 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["906" "Sun" "31" "December" "1995" "03:38:27" "-0800" "Steve VanDevender" "stevev@efn.org" nil "19" "Engineering Newsletter" "^From:" nil nil "12" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id DAA03559; Sun, 31 Dec 1995 03:37:23 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id DAA19347; Sun, 31 Dec 1995 03:38:27 -0800 Message-Id: <199512311138.DAA19347@tzadkiel.efn.org> In-Reply-To: <199512302106.AA16549@student.utwente.nl> References: <199512302106.AA16549@student.utwente.nl> From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Engineering Newsletter Date: Sun, 31 Dec 1995 03:38:27 -0800 This page is _so cool_ that I've stayed up until 3:30 am looking at it: http://www.fourmilab.ch/cship/cship.html Although his starship design is simplistic and intended more for expository purposes than as a completely realistic design, it does have some interesting features I haven't seen us discuss before. In particular he discusses the need for streamlining (!) for a ship that travels at high relativistic speeds. In essence it's a self-powered ship fueled by antimatter. The coolest part, though, is a couple of MPEGs that show trips through his imaginary "lattice galaxy" at relativistic speeds. This is exactly the kind of thing I want to do with my starship simulation program (still completely embryonic at this point), but with a database of real stars in the Solar neighborhood. View the MPEGs, and then we can talk about why it looks like you're flying backwards at the start of a trip. From popserver Wed Nov 29 07:08:42 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5582" "Tue" "28" "November" "1995" "23:07:53" "-0800" "Steve VanDevender" "stevev@efn.org" nil "109" "Re: Summarry of the momentum wars and idea." "^From:" "KellySt@aol.com, stevev@efn.org, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "KellySt@aol.com, stevev@efn.org, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "11" nil nil nil nil] nil) Received: from tzadkiel.efn.org by efn.efn.org (4.1/smail2.5/05-07-92) id AA05662; Tue, 28 Nov 95 23:04:17 PST Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.1/8.7.1) id XAA00455; Tue, 28 Nov 1995 23:07:53 -0800 Message-Id: <199511290707.XAA00455@tzadkiel.efn.org> In-Reply-To: <951128203350_119181713@emout06.mail.aol.com> References: <951128203350_119181713@emout06.mail.aol.com> X-UIDL: 817628697.000 From: Steve VanDevender To: KellySt@aol.com Cc: stevev@efn.org, hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Summarry of the momentum wars and idea. Date: Tue, 28 Nov 1995 23:07:53 -0800 KellySt@aol.com writes: > >> Besides not treating momentum as a vector quantity, people are > >> making the mistake of thinking that lateral loading of the sail > >> assembly is a magical sink for momentum or energy. The error is > >> in thinking that stress on a static structure absorbs energy or > >> momentum continuously over time. If the sail does not move > >> relative to the ship, then it cannot absorb or dissipate momentum > >> separately from the ship. It cannot absorb momentum if it does > >> not move, because momentum means motion. ---- > > (??!) > Thats like the old argument that if a tractor is pushing against a wall its > doing no work, since the wall isn't accelerated. The sail is getting a > thrust that is perpendicular to the surface of reflection. If you want to > describe the portion of the thrust that isn't accelerating the ship as > invalid, enjoy. The tractor is dissipating energy because it contains moving parts in its engine and drive train that keep moving even though the tractor chassis and the wall are not. And it did do some amount of work compressing itself against the wall; when the engine is turned off, the tractor will roll away from the wall. Lean a board against the wall. Does it dissipate energy because it can't move the wall? Lean a heavy iron bar against the wall. Does it dissipate more energy than the board? Are the bricks at the bottom of the wall permanently warmer than the bricks at the top because they are under compression? These are all what I mean by static stress. Static stress does not dissipate energy. Varying stress dissipates energy; the tractor engine powered by intermittent gasoline explosions produces vibration and heat as it pushes the tractor against the wall; the tractor vibrating against the wall even heats the wall. On the other hand, the board or the iron bar, or the bricks at the bottom of the wall, do not dissipate energy. If you think they do, tell me where it comes from. You can't claim that gravity is continuously pumping energy into the objects; you can't gain or lose energy if you don't move up or down in a gravity field. > But when you start to mutter things like: > >> ---as long as the sail does not fall apart or the support > >> members do not break, no more energy is dissipated into > >> loading of the sail structure. > > We have a problem. > > A considerable amount of energy will be continuously loaded and (hopefully) > disapated by the sail cross webbing. If we don't consider it, and make sure > the structure can disapate it, the cross cables will melt under the energy > they have to disapate under this lateral thrust load. The structure will dissipate energy if the photon beam varies periodically with time, as the up-and-down variations will induce vibration in the structure. This is certainly a real engineering problem that would have to be considered in a real ship. My intention was to prove that Kevin's parasail design couldn't absorb photons without absorbing their momentum. This principle is still true even if the parasail isn't exposed to a completely steady, unvarying photon flux. The members of the support structure don't "dissipate" or "absorb" forward momentum because they are under sideways load. You seem to have a real misunderstanding of the difference between work and potential. When you put a structure under tension or compression, you do change its energy, ONCE, when you slightly pull apart or scrunch together all of the atomic bonds in the object; you have put potential energy into the object. As long as the forces on the structure do not change, no further energy flows in or out of it; it does not continue to dissipate energy with time. Your house does not radiate heat because it is in a gravity field. The cornerstone of the Empire State Building is not hot because it is holding up the weight of the building. The Earth is not losing energy to everything that its gravity holds to the ground. Just as I could build a reactionless drive from Kevin's parasail, if I play by your rules I can build a perpetual motion machine from a piece of metal in a vise; all I have to do is extract the energy that you claim it will continually radiate for as long as it is in the vise. The reason that real engineering structures dissipate energy is that there is rarely such a thing as pure static stress. Structures endure varying loads -- cars drive over bridges, the Empire State Building sways in the wind and absorbs millions of footsteps. The cornerstone of the Empire State Building isn't warmer because it's under compression; it's warmer because it dissipates energy from swaying and vibration. > One very consistent problem in LIT over the last year has been > a very limited interest in the engineering realities of a > situation, and to much fondness for endless equation wars. These are not equation wars; as this message shows, you don't always have to use math to talk about physics. We are talking about very real physics concepts, and I'm afraid you are the one who has a few important ones wrong. Before we can do the detailed engineering for a starship, we need to understand what physical constraints it will be under. Even the best engineering cannot violate the laws of physics. If we are engaged in "equation wars", it is because we are trying to figure out the limits of what is possible before we do detailed design work based on faulty assumptions. This is the most fundamental interest in engineering realities you could want. From popserver Wed Dec 27 06:39:47 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["631" "Tue" "26" "December" "1995" "21:45:58" "-0800" "Steve VanDevender" "stevev@efn.org" nil "15" "RE: RE: Engineering Newsletter" "^From:" "David@InterWorld.com, hous0042@maroon.tc.umn.edu, jim@bogie2.bio.purdue.edu, KellySt@aol.com, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, zkulpa@zmit1.ippt.gov.pl" "David Levine, hous0042@maroon.tc.umn.edu, jim@bogie2.bio.purdue.edu, 'KellySt@aol.com', rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl, zkulpa@zmit1.ippt.gov.pl" "12" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.2/8.7.2) with ESMTP id WAA15692; Tue, 26 Dec 1995 22:32:54 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id VAA04686; Tue, 26 Dec 1995 21:45:58 -0800 Message-Id: <199512270545.VAA04686@tzadkiel.efn.org> In-Reply-To: References: From: Steve VanDevender To: David Levine Cc: "hous0042@maroon.tc.umn.edu" , "jim@bogie2.bio.purdue.edu" , "'KellySt@aol.com'" , "rddesign@wolfenet.com" , "RUSSESS@cellpro.cellpro.com" , "stevev@efn.org" , "T.L.G.vanderLinden@student.utwente.nl" , "zkulpa@zmit1.ippt.gov.pl" Subject: RE: RE: Engineering Newsletter Date: Tue, 26 Dec 1995 21:45:58 -0800 David Levine writes: > Oh, as for my previous post - I do apologize - I've checked my archives > and have also received some CCs from Steve and a few from Ric > (plus one from Zenon). I have pretty much been following up to whatever recipient list is attached to whatever post I'm commenting on. I noticed your name was on some of the messages we've been passing around. I've saved copies of most of the messages sent to me since I started receiving them. If you are interested I could arrange to get that mail folder to you. It's a bummer to hear about SunSITE; I had been depending on it as a Linux software archive too. From popserver Mon Jan 1 18:58:15 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1070" "Mon" "1" "January" "1996" "11:02:36" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "28" "Happy New Year" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id KAA25449 for ; Mon, 1 Jan 1996 10:56:44 -0800 (PST) Received: from sea-ts2-p17.wolfenet.com (sea-ts2-p17.wolfenet.com [204.157.98.135]) by wolfe.net (8.7.3/8.7) with SMTP id LAA16684; Mon, 1 Jan 1996 11:02:36 -0800 (PST) Message-Id: <199601011902.LAA16684@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Happy New Year Date: Mon, 1 Jan 1996 11:02:36 -0800 (PST) Happy New Year everyone!! Well, I have done the first of my new years projects. I created a mailing group for this group. No more cutting and pasting for this guy in the new year. Well, what do we want to get completed this year? Mission Plans were few. the mission still needs to be defined. Engins!! Boy, is that a topic. I don't know the physics of all of this but it seems that we just don't have the technology yet to get what we need for this project. I hope I'm wrong, soon. Without knowing the mission or propulsion, the size of the ship isn't known. Hab spaces are seem to be dependent on the first two. Crew size is determined by ship and habitat sizes. The means of getting to TC or where ever it is we decide to go does seem to revolve around a power plant though. The question, to me, is, if we can't do it yet, why not pick a more realistic and closer goal that we could expect to acchive by 2040 or 2050. The above opinions are my own and do not reflect those of the management. :-) Ric The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Tue Jan 2 03:16:58 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1692" "Tue" "2" "January" "1996" "00:36:50" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "39" "Re: Happy New Year" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id PAA05399 for ; Mon, 1 Jan 1996 15:35:41 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA12594 (5.67b/IDA-1.5 for ); Tue, 2 Jan 1996 00:36:45 +0100 Message-Id: <199601012336.AA12594@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Happy New Year Date: Tue, 02 Jan 1996 00:36:50 +0100 >Well, I have done the first of my new years projects. I created a mailing >group for this group. No more cutting and pasting for this guy in the new year. Didn't you do that before? How for heaven sake have you been archieving 140 letters? >Engins!! Boy, is that a topic. I don't know the physics of all of this but >it seems that we just don't have the technology yet to get what we need for >this project. I hope I'm wrong, soon. The problem is the amount of power needed, no technology of today except for H-boms can give us that power easely. >Without knowing the mission or propulsion, the size of the ship isn't known. >Hab spaces are seem to be dependent on the first two. If we want to go to TC, habsize doesn't depend on the kind of propulsion, we just NEEDS space to live and work in. Every extra kilogram that is not needed should be eliminated regardless of the type of engine. >The means of getting to TC or where ever it is we decide to go does seem to >revolve around a power plant though. The question, to me, is, if we can't do >it yet, why not pick a more realistic and closer goal that we could expect >to acchive by 2040 or 2050. What about a mission to Venus? The high temperatures would make it a nice challenge. Or the outer regions of our solar system, doing it as fast as possible, ie. using 1g all the time. The trip would take about 3 weeks. We could of course stay on Earth and look for a way to easely go to the bottom of the oceans. A submarine that isn't limited by 300 or 1000 metres of depth. >The best Beads come from RD Designs. Ric, are these Beads the beads on a cord? (I wondered about this since the first time I read your signature) Timothy From popserver Tue Jan 2 07:07:12 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1323" "Mon" "1" "January" "1996" "23:04:45" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "36" "Re: Happy New Year" "^From:" "T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "Timothy van der Linden, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id XAA21897 for ; Mon, 1 Jan 1996 23:05:26 -0800 (PST) Received: from sea-ts2-p41.wolfenet.com (sea-ts2-p41.wolfenet.com [204.157.98.159]) by wolfe.net (8.7.3/8.7) with SMTP id XAA14744; Mon, 1 Jan 1996 23:04:45 -0800 (PST) Message-Id: <199601020704.XAA14744@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Happy New Year Date: Mon, 1 Jan 1996 23:04:45 -0800 (PST) >>Well, I have done the first of my new years projects. I created a mailing >>group for this group. No more cutting and pasting for this guy in the new year. > >Didn't you do that before? How for heaven sake have you been archieving 140 >letters? What I ment was I created a "mailing list" under one heading. (LIT). It contains everyone's names who has been active in this e-mail newsletter. >What about a mission to Venus? The high temperatures would make it a nice >challenge. >Or the outer regions of our solar system, doing it as fast as possible, ie. >using 1g all the time. The trip would take about 3 weeks. >We could of course stay on Earth and look for a way to easely go to the >bottom of the oceans. A submarine that isn't limited by 300 or 1000 metres >of depth. 3 weeks? what speed would you be traveling at? I don't have the real figure but aren't our present space craft traveling at 10's of thousands of miles a minute? > >>The best Beads come from RD Designs. > >Ric, are these Beads the beads on a cord? (I wondered about this since the >first time I read your signature) I keep forgetting to turn off that darn thing. We seel strings of beads as well as bags of beads. Do you have an interest? I could get you some prices if you like. Ric The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Tue Jan 2 09:34:23 GMT 1996 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["10557" "Tue" "2" "January" "1996" "01:30:13" "-0800" "Steve VanDevender" "stevev@efn.org" "<199601020930.BAA25497@tzadkiel.efn.org>" "231" "Re: C-ship" "^From:" "T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org" "Timothy van der Linden, stevev@efn.org" "1" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id BAA25840; Tue, 2 Jan 1996 01:29:04 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id BAA25497; Tue, 2 Jan 1996 01:30:13 -0800 Message-Id: <199601020930.BAA25497@tzadkiel.efn.org> In-Reply-To: <199601012207.AA10231@student.utwente.nl> References: <199601012207.AA10231@student.utwente.nl> From: Steve VanDevender To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: stevev@efn.org Subject: Re: C-ship Date: Tue, 2 Jan 1996 01:30:13 -0800 Timothy van der Linden writes: > >I am still trying to get enough understanding of special > >relativity theory to make sure I get things right. I also want > >to work out more of the mathematical techniques I will use. > > Once that is ready, writing the simulator is easy ;) Yes, and that's why I've spent all my time on that so far, with a relatively brief digression into astrophysics to develop a simple but adequate model of starlight and a 3-d star database from catalogs. > >The basic structure of the simulation will be to model worldlines > >for all objects, and compute visibility for display by tracing > >light-like worldlines from a observer point to the other > >worldlines in the simulation in some common frame, then transform > >apparent positions of these objects in the common frame into the > >frame of the observer. > > Indeed, but for this you need to have a history of all the objects positions. > As long as they move linear or linear accelerated that's not so difficult > because you can use a function. But as soon as the behaviour gets less > simple you may need large arrays and with it come less precise calculations. > Also it would be nice to see the time at every point of the several objects > (for example by halting the simulation and clicking with the mouse). I realize that a motion history is necessary. In fact, the fundamental information associated with a typical object will be a worldline, consisting of straight and accelerated segments. The worldline represents the full motion history of an object, so in theory you could go to any point in spacetime in any frame and get a view of the universe by tracing intersections to the worldlines of all the other objects, then transforming those displacements into the view frame. I recognize the problem of dealing with more complicated types of motion. I at least want to work out a reasonable method of handling orbital motion so you can see what it looks like to boost into or out of a solar system. > >I think most of the relativistic effects, particularly things > >like aberration and rotation induced by moving at relativistic > >speed, can come out of fundamental behavior of the simulation > >rather than having to be explicitly calculated in each case. > >Aberration is simply a result of the way worldlines of light rays > >Lorentz-transform. > > Rotation will indeed follow from the finite speed of light. But I don't see > how abberation does not show up after the LT of the worldlines. Lightrays > coming form the backside of the observer won't come from the front after the LT. Check out the exercises in Chapter L (that's what they call it) of _Spacetime Physics_. Aberration and the "headlight effect" both follow directly from the geometry of the Lorentz transformation applied to light rays. Remember that a displacement along a worldline of a light ray is different than a plain spacial displacement, so applying a Lorentz transform to it produces a different result. Try out the numbers and I think you'll be surprised. I just ran an example for myself with a Lorentz transform matrix for a boost of 0.9 c in the x direction, and light rays coming from a perpendicular direction (say from along the y or z axes). They really do end up looking like they're in front of you when transformed into the "moving" frame. > >Rather than seeing Lorentz contraction, you > >see object rotation, because you see light from farther parts of > >an object that came from it earlier than light from nearer > >parts. I am trying to prove to myself that all these effects > >will fall out of the simulation model I want to use; so far I am > >pretty confident that I'm on the right track. > > This rotation is only seen if the object moves along you, thus not towards you. Correct. If your optics all take into account the finite speed of light, though, you will not necessarily see the amount of Lorentz contraction you'd think. Farther portions of the object are seen farther back in time when they were farther away. > >>What I asked John Walker was that I would expect curved lines in the SHUTTLE > >>and FLYTHRU movies. I think this curvature would be result of the finite > >>travel speed of light, ie. light from further objects reach the observer > >>later than the light from nearer object. > > > >That effect should happen. > > I've been rethinking this bending of the lines today. And now I think that > the lines should be straight. The lines are only curved if the objects are > moving. If the observer is moving and the objects don't move this bending > will not occur. What do you think after reading this? > > This would mean that you could "easely" recognize moving objects because of > the curvature they have and that still objects don't have. Which is why you should be suspicious. In the case of a constant-velocity observer, it is not possible to decide whether the observer or its surroundings are moving. (An accelerated observer experiences something that the rest of the universe does not; an accelerated observer knows that he is accelerating.) The appearance of curvature for large fast-moving objects will happen. Your arbitrary decision of whether the object is still or moving does not affect the geometry of the light; you can simply apply a Lorentz transform to the situation where the ship is moving and the object is still and get the situation where the ship is still and the object is moving, with the same view from the ship. The appearance of curvature is an effect of the finite speed of light. A snapshot of a scene captures light that arrived at the camera all at the same time. So light from farther portions of an object must have been emitted earlier, when the farther portions were farther back in their motion history, in order to be seen at the same time as light from nearer portions. This effect only becomes pronounced if the object subtends a large part of the field of view and is moving at a large fraction of c. > Yes, you need to know the functions of motion several points of an object. > Let's call one point of the object P[t]. > Call the point of the observer O[t]. > What does the observer see at time T1? The observer sees an object if a > photon that left the object at time T0 reached the position O[T1]. > > So in formula's: > > c*(T1-T0)=Sqrt((O[T1]-P[T0])^2) c is the speed of light > > With this equation one can calculate T0. When knowing that, you can > determine the position of the object at T0, so then you know from what > direction and from how far the photon came. > > Do this for all object-points and you have a created the "see-able" world, > after that you could use the c-ship program. That's the basic approach, although I use 4-vectors to represent time and position in the same object. First, for a U = [ u0 u1 u2 u3 ] and V = [ v0 v1 v2 v3 ], U|V = u0*v0 - u1*v1 - u2*v2 - u3*v3 (Lorentz inner product), and U^2 = U|U. U^2 is the square of the spacetime interval of a displacement represented by U. Velocities are neatly represented by vectors V where V^2 = 1; the components of the vector can be interpreted as displacements in frame coordinates per unit object time. Convert a frame velocity V = [ 1 v1 v2 v3 ] into a unit vector by dividing all components by sqrt(V^2). If you are at a point S = [ t x y z ], and you want to view an object whose worldline is described by P(t') = P0 + V * t' = [ t0 x0 y0 z0 ] + [ v0 v1 v2 v3 ] * t', then the path of a light ray between S and P satisfies the equation (S - P(t'))^2 = 0, The solution is: t' = ((S - P0)|V - sqrt(((S - P0)|V)^2 - (S - P0)^2 * V^2)) / V^2 This is pretty much simple application of the quadratic formula, choosing the smallest solution to get the t' that corresponds to light leaving the object at an earlier time than the observer's. Things are substantially more complicated when dealing with accelerated worldlines. I've got a preliminary solution stated in similar terms as the above discussion; perhaps you'd like to check my math :-). You are at the point S = [ t x y z ] attempting to view an object whose coordinates are P(t') = 1/a^2 * [ a * sinh(a * t') ax * (cosh(a * t') - 1) ay * (cosh(a * t') - 1) az * (cosh(a * t') - 1) ] where the acceleration is represented by A = [ 0 ax ay az ] (in the object local frame) and a = sqrt(ax^2 + ay^2 + az^2) (the magnitude of the acceleration). So again, we want to solve the equation (S - P(t'))^2 = 0. Of course, the components of P(t') are much more complicated. I won't bore you with the full derivation, other than to note that it becomes easier to isolate t' by writing the sinh and cosh terms in terms of their definitions using exp (e^x). Eventually, you get: exp(a * t')^2 * (1 - A|S - a * t') + exp(a * t') * (a^2 * S^2 - 2 * (1 - A|S)) + (1 - A|S + a * t') = 0 It's convenient to make some substitutions for common subexpressions: k = 1 - A|S p = k - a * t' q = a^2 * S^2 - 2 * k r = k + a * t' So then applying the quadratic formula and isolating t' gives: t' = 1/a * ln((-q - sqrt(q^2 - 4 * p * r)) / (2 * p)) I have yet to program this expression into my calculator and play with some solutions to see if they have the predicted results. In particular, there should be regions of spacetime where you cannot see the accelerated object (see Chapter 6 of _Gravitation_). You will also note that this is a somewhat less general statement of the problem; it uses a frame in which the accelerated object was at rest at the origin of the frame. For a general solution you would need to transform the view point into the appropriate frame, apply this solution, and transform it back out afterwards. > >Now that I think about it, simple extensions to POVray for > >modeling relativistic effects probably wouldn't work well, > >because you really have to raytrace in four dimensions to > >properly model them. > > Indeed, although it is easy to calculate the length of the lightray, it is > much more difficult to know where all object where in the past. For the purposes of the guy's C-ship simulation he would have to model acceleration, at least, which would substantially complicate things. My plan for my simulation will be to develop some heuristics to find the right worldline segment to which to apply the analytic solutions above, and possibly some other heuristics to discard old pieces of worldlines that are no longer visible to other important simulation objects. From popserver Tue Jan 2 10:16:55 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1770" "Tue" "2" "January" "1996" "02:14:26" "-0800" "Steve VanDevender" "stevev@efn.org" nil "60" "Re: C-ship" "^From:" "stevev@efn.org, T.L.G.vanderLinden@student.utwente.nl" "Steve VanDevender, Timothy van der Linden" "1" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id CAA26814; Tue, 2 Jan 1996 02:13:24 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id CAA25641; Tue, 2 Jan 1996 02:14:26 -0800 Message-Id: <199601021014.CAA25641@tzadkiel.efn.org> In-Reply-To: <199601020930.BAA25497@tzadkiel.efn.org> References: <199601012207.AA10231@student.utwente.nl> <199601020930.BAA25497@tzadkiel.efn.org> From: Steve VanDevender To: Steve VanDevender Cc: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Subject: Re: C-ship Date: Tue, 2 Jan 1996 02:14:26 -0800 Steve VanDevender writes: > Things are substantially more complicated when dealing with > accelerated worldlines. I've got a preliminary solution stated > in similar terms as the above discussion; perhaps you'd like to > check my math :-). > > You are at the point S = [ t x y z ] attempting to view an object > whose coordinates are P(t') = > > 1/a^2 * [ a * sinh(a * t') > ax * (cosh(a * t') - 1) > ay * (cosh(a * t') - 1) > az * (cosh(a * t') - 1) ] > > where the acceleration is represented by A = [ 0 ax ay az ] (in > the object local frame) and a = sqrt(ax^2 + ay^2 + az^2) (the > magnitude of the acceleration). > > So again, we want to solve the equation (S - P(t'))^2 = 0. Of > course, the components of P(t') are much more complicated. I > won't bore you with the full derivation, other than to note that > it becomes easier to isolate t' by writing the sinh and cosh > terms in terms of their definitions using exp (e^x). > > Eventually, you get: > > exp(a * t')^2 * (1 - A|S - a * t') + > exp(a * t') * (a^2 * S^2 - 2 * (1 - A|S)) + > (1 - A|S + a * t') > = 0 Sigh. That should actually be: exp(a * t')^2 * (1 - A|S - a * t) + exp(a * t') * (a^2 * S^2 - 2 * (1 - A|S)) + (1 - A|S + a * t) = 0 I wrote t' rather than the t component of S in a couple wrong places. > It's convenient to make some substitutions for common > subexpressions: > > k = 1 - A|S > p = k - a * t' > q = a^2 * S^2 - 2 * k > r = k + a * t' And these should be p = k - a * t q = a^2 * S^2 - 2 * k r = k + a * t > So then applying the quadratic formula and isolating t' gives: > > t' = 1/a * ln((-q - sqrt(q^2 - 4 * p * r)) / (2 * p)) Fortunately I still copied that correctly. From popserver Tue Jan 2 18:01:55 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["498" "Tue" "2" "January" "1996" "06:41:54" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "16" "New Year Resolutions" "^From:" "rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "rddesign@wolfenet.com, Timothy van der Linden, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id EAA29533 for ; Tue, 2 Jan 1996 04:41:36 -0800 (PST) Received: by maroon.tc.umn.edu; Tue, 2 Jan 96 06:41:55 -0600 In-Reply-To: <199601020704.XAA14744@wolfe.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: rddesign@wolfenet.com cc: Timothy van der Linden , KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: New Year Resolutions Date: Tue, 2 Jan 1996 06:41:54 -0600 (CST) This year (1996) I resolve to: 1) to find a physically consistent means to slow down the Asimov from lightspeed, assuming that all the energy we want can be beamed from Sol. 2) to find a physically consistent means to beam that energy. 3) to buy and read "spacetime physics" note, "physically consistent" means that it satisfies all know physical laws, esp. conservation of momentum and energy Kevin PS Happy New Year Guys! May it be a healthy and productive one in all your pursuits. From popserver Tue Jan 2 18:28:20 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1544" "Tue" "2" "January" "1996" "19:27:10" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "41" "Re: Happy New Year" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id KAA14593 for ; Tue, 2 Jan 1996 10:26:10 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA00685 (5.67b/IDA-1.5 for ); Tue, 2 Jan 1996 19:27:05 +0100 Message-Id: <199601021827.AA00685@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Happy New Year Date: Tue, 02 Jan 1996 19:27:10 +0100 ReplyTo: Ric >>What about a mission to Venus? The high temperatures would make it a nice >>challenge. >>Or the outer regions of our solar system, doing it as fast as possible, ie. >>using 1g all the time. The trip would take about 3 weeks. >>We could of course stay on Earth and look for a way to easely go to the >>bottom of the oceans. A submarine that isn't limited by 300 or 1000 metres >>of depth. > >3 weeks? what speed would you be traveling at? I don't have the real figure >but aren't our present space craft traveling at 10's of thousands of miles a >minute? The distance to Pluto is about 6E12 metres, you need half that distance to accelerate and the other half to decelerate. x = 0.5 g t^2 --> t = Sqrt(2x/g) = Sqrt(6E12/9.8) = 7.8E5 seconds = 9 days So it takes 9 days to accelerate and 9 to decelerate. Ok, how fast are we going after accelerating: 7.8E5 * 9.8 = 7.7E6 m/s = 2.1E6 km/h = 1.3E6 mph That is 0.026c and it will give us a gamma of 1.0033 The total trip will take about 5.5 minutes less due to the relativistic effects. >>>The best Beads come from RD Designs. >> >>Ric, are these Beads the beads on a cord? (I wondered about this since the >>first time I read your signature) > >I keep forgetting to turn off that darn thing. We seel strings of beads as >well as bags of beads. Do you have an interest? I could get you some prices >if you like. No, that won't be necessary, I wouldn't have a purpose for them. >Ric >The best Beads come from RD Designs. >Ric & Denisse Hedman There you did it again :) Timothy From popserver Thu Jan 4 03:09:44 GMT 1996 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["960" "Wed" "3" "January" "1996" "21:00:38" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<960103205747_105827744@emout06.mail.aol.com>" "26" "Re: Happy New Year" "^From:" "rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id SAA27165 for ; Wed, 3 Jan 1996 18:00:08 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id VAA18508; Wed, 3 Jan 1996 21:00:38 -0500 Message-ID: <960103205747_105827744@emout06.mail.aol.com> From: KellySt@aol.com To: rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Happy New Year Date: Wed, 3 Jan 1996 21:00:38 -0500 >What about a mission to Venus? The high temperatures would make it a nice >challenge. >Or the outer regions of our solar system, doing it as fast as possible, ie. >using 1g all the time. The trip would take about 3 weeks. >We could of course stay on Earth and look for a way to easely go to the >bottom of the oceans. A submarine that isn't limited by 300 or 1000 metres >of depth. >> 3 weeks? what speed would you be traveling at? I don't >> have the real figure but aren't our present space craft >> traveling at 10's of thousands of miles a minute? More like 20 - 30 thousand MPH. Far too slow to cover solar systems distences quickly. But we do know of much better systems. We could work on a Alpha Centuri flight. Thats closer to our capacity. Oh, as far as cabin space. Its going to need to be big because of the need for a large diameter centrafuge, and because the crew will need a lot of room to keep from going stire crazy! Kelly Kelly From popserver Thu Jan 4 03:09:45 GMT 1996 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["10053" "Wed" "3" "January" "1996" "21:00:18" "-0500" "KellySt@aol.com" "KellySt@aol.com" "<960103205728_105827437@emout06.mail.aol.com>" "224" "Re: Engineering Newsletter" "^From:" "T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id SAA27273 for ; Wed, 3 Jan 1996 18:01:43 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id VAA18072; Wed, 3 Jan 1996 21:00:18 -0500 Message-ID: <960103205728_105827437@emout06.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Wed, 3 Jan 1996 21:00:18 -0500 Tim thanks for forwarding the missing letter. Re: Timothy replies to Kelly: > > >>You can't assume that more money is used for this, because I could assume > >>that more money is used for research for anti-matter containment and > >>creation. Both fusion and anti-matter are areas where little is known > >>about. > > > >I wasn't refering to LIT assumptions, only real world. But, if we are to > >assume a large scale space infastructure. I guess we can assume it was worth > >there while to develope fusion systems. > > Indeed, but so would anti-matter systems after a while. Fusion is an extreamly usefull general purpose technology. Anti-matter is far less so, and far more dangerous on the scale we would need. I wouldn't expect a lot of anti-mater ships in 50 years. > >>Doing research on a planet or building industries is still much more > >>interesting than flying back to Earth. And if it isn't more intersting, then > >>research will gives more fruits for the money than flying back would do. > > > >Building industries? I don't follow. > > For some kind of colonization. Even if it is used as "refresh" point for > future missions to other solarsystems, it needs some form of > selfsufficiency. Therefor it needs "farms" and buildings, you can't make > them all by hand, so you need some form of small industry. Oh, that would be beyond the resources and tech of the project. Also it seem a waste of time. Sort of novelty project for the record books. With no practical reason to stay perminently there the bases would be prefab ghost towns. Future missions to other solar systems would have to be based out of dynamic, growing, large scale, civilizations. Not out of a staging camp in the middle of nowhere. > >Research I can understand, but obviously they can't do that forever. > > Why not, there will be plenty to figure out. Forever? Do you expect earth to keep funding these people in this base forever? With continuous supply flights from sol to keep them going? We couldn't even keep the moon program going for more than a few months after it planted its flag. > >Nor do I expect to settle for living out the rest of their lives in the hab > >deck. > > Why don't you expect them to do that? I still don't see that as suicide, > they can live perfectly healthy lives. Thats like condeming somone to spend the rest of their lives in an apartment/shoping mall! Good researchers will want to retire or go on to other projects. Not sit around in a worn out ship, in the middle of nowhere, with nothing to do. > >I can't see corporations droping probably hundreds of billions of dollars on > >a project like this. It absolutly would have no short term benifit (decades > >at least) and advertizing would supply this kind of money. > > One Japanese building company is seriously thinking about how it could build > on the moon. Now it may be a sign of advancement(=adverticement) but in 20 > years they may be the first(=money) to build there. > Indeed one company would not have enough money, but one company alone could > not build a city, so several companies will take their share. > And after all, the government's money is in fact the money of the companies. Japanise think big (and talk big), but seldom can carry out those big plans. Companise are in busness to make money for people. If they don't do that, they are taking their investors money under false pretenses. Which can get their executives fired or jailed. Droping money on a scale like this for no reasone other than as a charity project for prospace people would be criminal mis-appropriation, and comercial suicide. Assuming they weren't thrown in jail, the company would be so weak another pragmatic company could easily take it over. > >International projects ARE A DISSASTER!! I was in the International Space > >Station Freedom Program, and can assure you it convinced about everybody that > >international cost everyone far more, slowed the program WAY down, and > >generally made it impossible. If a project like this requirers international > >particip[ation, it will be a write off. > > May be, but a single country couldn't do it either. I don't know all about > problems about Freedom, but wasn't NASA the main "sponsor"? A single country could have done it far cheaper and quicker then all combined. > Such a project would be a challenge for mankind, it would not ALLOW us to > work together, it would INSIST us working together. Maybe today such a > project will not work, but countries are aligning. I know this sound > biblical: "When all sheep listen to one herdsman...", but I think it's > better than that: "The sum of the parts is much more than the parts themselves". Sorry, no. In large projects like this the sum of the parts is the lowest common denominator of everyone. It becoming a big issue in the U.S. The more people you get on a project, the less energy and inovation is avalible. Things get bogged down, lost in committe misunderstanding, ecetera. Costs can go up to hundreds of times what a small tight group could do it for. Thats one of the reasons that over the last decade or two, NASA has been incapable of trying, or developing, cutting edge technologies or programs. > >> So how do we solve that? Walking in spacesuits all day isn't that much fun. > > > >Exploration is seldom a lot of fun. I can't think of anyway to solve the > >biohazard problem other than space suits, or staying in the ship and using > >tele-operated robots. > > Exploration isn't much fun? What else drives people to such far places... Curiosity, greed, a chalenge, desire for fame or acomplishment. Exploration is generally horiobly uncomfortable and life threatening. But its very chalenging, and its atractive to know your one of the few to ever do something, know something, etc... Even if you know its killing you. Like an anthro professor my wife had. He loved studying aborigional tribes in the backwaters of the Amazon, but he frely admitted everyone who does it expect that they've paid with decades off their life expectancy. A ground team to a worl with a eath like bioshpere could expect to losemost of the team over a couple of months even inside the biosuits. > >> The place I live is save, even if all the polar ice melts away. :) (33 > >> metres above sealevel) > >> What you write may be true, but is not complete, we have found cures for > >> many diseases and our understanding gets better all the time. In 50 years > >> this will only be better and more advanced. > > > >True, but its taken us centuries to get this far in our medical skills. We > >won't have centuries, or even decades, to learn how to fight the alien > >bio-hazards. > > In all these centuries we accumulated these skills, a lot of these skills > can be used as general solutions and not as specific solutions. Often if a > cure for one disease is found, a lot of similar diseases are cured too. > It is not the specific case that takes decades to develop but the general > solution. So since we want to know what is out there, we will study those > creatures that have the potential to make us ill. Probably that is enough to > find a specific cure. Since your dealing with radically differnt life forms. Its unlikely the old rules, or solutions, would hold. We mostly will be starting from scratch. After all, we have no experience with alien biospheres. > >>>So if we want to continue the SD project we should make it 2140 instead of > >>>2040. > >> > >> Very possibly > > > >If we shove the calendar to 2140 from 2050, we'ld have nothing to base it on. > > We would have to debate what type of physics, much less engineering we could > >assume. > > So, what should we do? The main problem is the source of power that we are > allowed to use. So before we start discussing how the engine looks, we > should know what techniques we can use and in what AMOUNT. -- We're in a serous bind. The tech we can expect in 50 years isn't enough for a T.C. flight. Or all but the most modest interstellar flights. NOr would they be that likely to be interested in footing a huge program. Yet if we back up the date by a hundred years we could be much more confident that they could do it, and do it affordably, but we wouldn't have any credible idea how! > >We obviously arn't going to NEED to go to another star system, and certainly > >we've never come up with a reason anyone would want to stay in this other > >starsystem. (Trade obviously isn't practical with the technology we're > >discusing.) But that doesn't meen people wouldn't be interested in finding > >out what is there. > > It could be a goal for better survival of the human species. Two > so separate worlds are unlikely to become extinct at the same time. Your not talking about two planets. Your talking about earth, a fleet of colony platforms in sol and an outpost in another star. And the outpost is totally dependand on sol. Put another way. Are we that likely to be so afraid of human extinction, that we'll rush to do such a project in 50 years? > The reason for people to stay in such a desolated area is quite obvious, to > start a new or other life. Think of the people that went to Australia the > last 50 years (not the prisoners), a lot of them wanted new chances. Chances > they could not realize at their previous home. My guess is that there are > millions of people that want to get away from their present life and start > somewhere else. Oh certainly. The united states gets several million of them a year! But, another star doesn't offer much opportunity. It isolated, expensive, no markets to go to, few resorces that you can get at. No home world to go to on vacation to. Your very dependand on the supply line from Sol, and their for far less independant than you would be in a colony in Sol. Also, the kind of people we would send on such a ship. Would be the ellete that would have a lot of opportunity back home. The people who want a new start, wouldn't be sent on the ship. Kelly From popserver Thu Jan 4 03:20:12 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["343" "Wed" "3" "January" "1996" "19:17:15" "-0800" "Steve VanDevender" "stevev@efn.org" nil "7" "Re: Happy New Year" "^From:" "KellySt@aol.com, rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "KellySt@aol.com, rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id TAA01802; Wed, 3 Jan 1996 19:16:07 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id TAA31203; Wed, 3 Jan 1996 19:17:15 -0800 Message-Id: <199601040317.TAA31203@tzadkiel.efn.org> In-Reply-To: <960103205747_105827744@emout06.mail.aol.com> References: <960103205747_105827744@emout06.mail.aol.com> From: Steve VanDevender To: KellySt@aol.com Cc: rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Happy New Year Date: Wed, 3 Jan 1996 19:17:15 -0800 KellySt@aol.com writes: > We could work on a Alpha Centuri flight. Thats closer to our capacity. Alpha Centauri is 4.3 lyr away. Tau Ceti is 10 lyr away. This is barely any difference as far as interstellar travel goes. If you can get to Alpha Centauri effectively, you can get to Tau Ceti with no more than about twice the travel time. From popserver Thu Jan 4 03:20:13 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["512" "Wed" "3" "January" "1996" "19:19:22" "-0800" "Steve VanDevender" "stevev@efn.org" nil "10" "Re: Engineering Newsletter" "^From:" "KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "KellySt@aol.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id TAA01934; Wed, 3 Jan 1996 19:18:12 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id TAA31210; Wed, 3 Jan 1996 19:19:22 -0800 Message-Id: <199601040319.TAA31210@tzadkiel.efn.org> In-Reply-To: <960103205728_105827437@emout06.mail.aol.com> References: <960103205728_105827437@emout06.mail.aol.com> From: Steve VanDevender To: KellySt@aol.com Cc: T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Wed, 3 Jan 1996 19:19:22 -0800 KellySt@aol.com writes: > Fusion is an extreamly usefull general purpose technology. Anti-matter is > far less so, and far more dangerous on the scale we would need. I wouldn't > expect a lot of anti-mater ships in 50 years. Perhaps not, but the only fuel that you can use to reach high relativistic speeds with a ship that carries its own fuel is antimatter. A fusion-powered ship carrying its own fuel can't reach high relativistic speeds without fuel-to-payload ratios of 10^6 or higher (much higher). From popserver Fri Jan 5 01:46:10 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["710" "Thu" "4" "January" "1996" "17:50:35" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "21" "Engineering Newsletter" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id RAA18283 for ; Thu, 4 Jan 1996 17:43:55 -0800 (PST) Received: from sea-ts1-p61.wolfenet.com (sea-ts1-p61.wolfenet.com [204.157.98.115]) by wolfe.net (8.7.3/8.7) with SMTP id RAA18479; Thu, 4 Jan 1996 17:50:35 -0800 (PST) Message-Id: <199601050150.RAA18479@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Engineering Newsletter Date: Thu, 4 Jan 1996 17:50:35 -0800 (PST) So what are we going to do? Our technology isn't quite there yet for the propulsion plant. I'm sure we could build the rest of the ship no problem. The people we would like to crew the ship and maybe colonize the new system probably won't want to go. We have funding problems. To small and not enought money. To large and you couldn't get folks to decide on when to have dinner much less pay for it. Where do we go? What do we do? Do we start in-system with projects on the moon and Mars and build to the larger prospect of inter-steller flight? Alpha Centauri is half the distance. Can we make it at half the speed? Ric the trouble maker :-) The best Beads come from RD Designs. Ric & Denisse Hedman From popserver Fri Jan 5 18:02:51 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["555" "Thu" "5" "January" "1995" "10:55:20" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "14" "Re: Happy New Year" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id BAA14323 for ; Fri, 5 Jan 1996 01:54:15 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA15120 (5.67b/IDA-1.5 for ); Fri, 5 Jan 1996 10:55:13 +0100 Message-Id: <199601050955.AA15120@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Happy New Year Date: Thu, 05 Jan 1995 10:55:20 +0100 Steve writes: >KellySt@aol.com writes: > > We could work on a Alpha Centuri flight. Thats closer to our capacity. > >Alpha Centauri is 4.3 lyr away. Tau Ceti is 10 lyr away. This >is barely any difference as far as interstellar travel goes. If >you can get to Alpha Centauri effectively, you can get to Tau >Ceti with no more than about twice the travel time. It depends, if you can just reach AC with a fusion engine in 15 years, then a round trip to TC would take at least 60 years. Not many would survive that trip simply because of age. Timothy From popserver Fri Jan 5 18:02:57 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7975" "Thu" "5" "January" "1995" "10:55:25" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "153" "Engineering Newsletter" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id BAA14330 for ; Fri, 5 Jan 1996 01:54:24 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA15130 (5.67b/IDA-1.5 for ); Fri, 5 Jan 1996 10:55:19 +0100 Message-Id: <199601050955.AA15130@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Engineering Newsletter Date: Thu, 05 Jan 1995 10:55:25 +0100 Timoty replies to Kelly: >Fusion is an extreamly usefull general purpose technology. Anti-matter is >far less so, and far more dangerous on the scale we would need. I wouldn't >expect a lot of anti-mater ships in 50 years. You shouldn't see anti-matter as a fuel, but more as efficient energy storage. Why is anti-matter not a fuel? Because we have to make it. Coparing these two is like comparing a petrol car with an electric car. The energy for an electric car has to come from other fuels. Although the weight advantage with electric cars may not be evident yet there are other advantages. One of the advantages is the independancy of the origin of the fuel source. If it is fusion, fission or solar energy all are easely converted to electric energy which is relative easy to handle. So what car-batteries are for us now, anti-matter will be for fast spacevessels. >Oh, that would be beyond the resources and tech of the project. Also it seem >a waste of time. Sort of novelty project for the record books. With no >practical reason to stay perminently there the bases would be prefab ghost >towns. Future missions to other solar systems would have to be based out of >dynamic, growing, large scale, civilizations. Not out of a staging camp in >the middle of nowhere. If it really is to get a entry in the record books and not much more that would really be a shame of all resources. If people really want to do that, I see the end of humanity near. About growing civilizations, I don't think that western cultures will expand that much. In the US the birthrate is 2.05 per female, in Europe it's about 1.8. So that would mean that population will decrease. The mean reason that Earth's population is still increasing are the less developed countries which have birthrates of 4 to 7. I think that families in developed countries have less children because of the care these children need (financial but also social/tutorial). So this means that we probably never need to go to other places. But if we want to explore and discover new places we may want outposts at many places. So building small colonies would not be that crazy then. These colonies would have two purposes, the outpost and a research function. There would probably many researchers that like to check a foreign planet. >Forever? Do you expect earth to keep funding these people in this base >forever? With continuous supply flights from sol to keep them going? We >couldn't even keep the moon program going for more than a few months after it >planted its flag. After some time they could have build a small colony with all facilities needed to live and work. The energy they need comes from TC itself. So Earth would need funding them, but since they have build a "nice" place in the middle of an interesting place they may be interested to hear something of them. You may argue that building a colony is difficult in an alien environment, but by that time we will have some experience in building things on the Moon or Mars. >> Why don't you expect them to do that? I still don't see that as suicide, >> they can live perfectly healthy lives. > >Thats like condeming somone to spend the rest of their lives in an >apartment/shoping mall! Good researchers will want to retire or go on to >other projects. Not sit around in a worn out ship, in the middle of nowhere, >with nothing to do. Other projects, they have all the choice they could have. Who's going to tell them that they cannot do what they want. The only limits are the ones of themselves. The people going there aren't the people who really want to retire, these are people that are born for exploration and research. (They really exist) My guess is that they wouldn't sit all the time in some ship or compartment, but that they would allow themselves to go to the planets surface (in spacesuits). >Sorry, no. In large projects like this the sum of the parts is the lowest >common denominator of everyone. It becoming a big issue in the U.S. The >more people you get on a project, the less energy and inovation is avalible. > Things get bogged down, lost in committe misunderstanding, ecetera. Costs >can go up to hundreds of times what a small tight group could do it for. And do you know why this happens, because everyone wants his own share and no one is prepared to accept an idea of an other because that will mean a loss of personal profit. >Thats one of the reasons that over the last decade or two, NASA has been >incapable of trying, or developing, cutting edge technologies or programs. Maybe even one country is too big? >> Exploration isn't much fun? What else drives people to such far places... > >Curiosity, greed, a chalenge, desire for fame or acomplishment. Exploration >is generally horiobly uncomfortable and life threatening. But its very >chalenging, and its atractive to know your one of the few to ever do >something, know something, etc... Even if you know its killing you. Sorry, I had a more lossy idea about the word exploration than you did, I meant approximately what you wrote. >Like an anthro professor my wife had. He loved studying aborigional tribes >in the backwaters of the Amazon, but he frely admitted everyone who does it >expect that they've paid with decades off their life expectancy. So that means a return trip won't be necessary. >Since your dealing with radically differnt life forms. Its unlikely the old >rules, or solutions, would hold. We mostly will be starting from scratch. > After all, we have no experience with alien biospheres. I doubt if they are so radically different, all lifeforms have to abide the laws of nature. Maybe some of them have found tricks that have not been found on Earth but that is why we are going there. And still if we know what doesn't work the chances of finding something that does work are enlarged. >We're in a serous bind. The tech we can expect in 50 years isn't enough for >a T.C. flight. Or all but the most modest interstellar flights. NOr would >they be that likely to be interested in footing a huge program. Yet if we >back up the date by a hundred years we could be much more confident that they >could do it, and do it affordably, but we wouldn't have any credible idea >how! So maybe we should say "a priori" that certain techniques are available. And discuss how and why these could be used. >Put another way. Are we that likely to be so afraid of human extinction, >that we'll rush to do such a project in 50 years? You can never tell :) people are worring about many things (like asteroids colliding with Earth or the Asimov :)) If humanity ever becomes extinct, it will be likely that it is not because of natural disasters. >Oh certainly. The united states gets several million of them a year! But, >another star doesn't offer much opportunity. It isolated, expensive, no >markets to go to, few resorces that you can get at. No home world to go to >on vacation to. Your very dependand on the supply line from Sol, and their >for far less independant than you would be in a colony in Sol. You indeed can't go on vacation, and it probably never will have more than 1000 inhabitants for the first 100 years. But as every place where people live, they will adapt themselves and the environment. Not all people want to become rich by selling stuff, a lot of them just want a place to life as they like with the "sky" as the only limit. As I said before dependancy is only a short time (if at all), once there is TC-light and gravity they can grow food just as on Earth. So the first necessaries of life should not be that difficult. >Also, the kind of people we would send on such a ship. Would be the ellete >that would have a lot of opportunity back home. The people who want a new >start, wouldn't be sent on the ship. If you are 25 to 30 how sure can you be that you are a member of that elite. Also it doesn't have to be a new start but a first very defiant start. Timothy From popserver Fri Jan 5 18:03:08 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["891" "Thu" "5" "January" "1995" "11:37:39" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "38" "" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id CAA15053 for ; Fri, 5 Jan 1996 02:36:26 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA17547 (5.67b/IDA-1.5 for ); Fri, 5 Jan 1996 11:37:32 +0100 Message-Id: <199601051037.AA17547@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Date: Thu, 05 Jan 1995 11:37:39 +0100 Available power sources: Fission Solar power Fusion Chemical Other? Available techniques: Beaming Energy storage in anti-matter Other? Places to go to: Tau Ceti (TC) Alpha Centaury (AC) Pluto Objectives: One way trip Two way trip Let's assume that all the above are possibilities. What we should do is calculate the size and feasability and discuss the (dis)advantages for all cases. We should NOT try to discard a method, but only give its advantages and disadvantages. Of course we have done a lot already, only we haven't ordered it very much. Maybe it is time to recapitulate our discussions. I think that we need a complete survey, of course every one knows a lot of it, but I think that we don't agree about everything yet, but we also don't know exactly what these differences are. So we should try to come up with a kind of report. (Of course easier said than done) Timothy From popserver Fri Jan 5 18:03:35 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3448" "Fri" "5" "January" "1996" "15:47:57" "+0100" "Zenon Kulpa" "zkulpa@lksu.ippt.gov.pl" nil "115" "Asimov DESIGN SPACE" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl, zkulpa@sunet.se" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl, zkulpa@sunet.se" "1" nil nil nil nil] nil) Return-Path: zkulpa@lksu.ippt.gov.pl Received: from sunic.sunet.se (sunic.sunet.se [192.36.125.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id GAA22205 for ; Fri, 5 Jan 1996 06:46:08 -0800 (PST) Received: from lksu.ippt.gov.pl by sunic.sunet.se (8.6.8/2.03) id PAA27365; Fri, 5 Jan 1996 15:47:20 +0100 Received: from zmit1.ippt.gov.pl by lksu.ippt.gov.pl (4.1/SMI-4.1) id AA18161; Fri, 5 Jan 96 15:47:57 +0100 Organization: Institute of Fundamental Technological Research Address: Swietokrzyska 21, 00-049 Warszawa, POLAND Message-Id: <9601051447.AA18161@lksu.ippt.gov.pl> From: zkulpa@lksu.ippt.gov.pl (Zenon Kulpa) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Cc: zkulpa@sunet.se Subject: Asimov DESIGN SPACE Date: Fri, 5 Jan 96 15:47:57 +0100 > From T.L.G.vanderLinden@student.utwente.nl Fri Jan 5 11:40:02 1996 > > Available power sources: > > Fission > Solar power > Fusion > Chemical > Other? > > Available techniques: > > Beaming > Energy storage in anti-matter > Other? > > Places to go to: > > Tau Ceti (TC) > Alpha Centaury (AC) > Pluto > > Objectives: > > One way trip > Two way trip > > Let's assume that all the above are possibilities. What we should do is > calculate the size and feasability and discuss the (dis)advantages for all > cases. We should NOT try to discard a method, but only give its advantages > and disadvantages. > Of course we have done a lot already, only we haven't ordered it very much. > Maybe it is time to recapitulate our discussions. I think that we need a > complete survey, of course every one knows a lot of it, but I think that we > don't agree about everything yet, but we also don't know exactly what these > differences are. > So we should try to come up with a kind of report. (Of course easier said > than done) > Here I would like to remind about my attempt (a year ago) to start recapitulation effort of all discussed options. Below follows the sketch of the beginning ;-)) of the DESIGN SPACE summary I have started then. There should be, of course, many more aspects listed, like target(s), life supply (e.g., stored food/hydroponics/farming; all crew awake/all crew hibernates(or something)/mixed, etc.), command structure, project financing.... &c &c. I think listing all the discussed possibilities, shortly and systematically, should help greatly in clearing the matter and see the whole forest instead of only trees (as Polish saying goes). *************************** * * * LIT "ASIMOV" * * Starship Design * * * *************************** Progress Report The DESIGN SPACE discussed: 1. Type of Mission: * Robotic * Fly-by (no braking nor stop at target) * Exploratory (stop at target & explore) * Pathfinder (ahead of manned one: scouting/early warning) * Supply (after the manned: catching on the way or at target) * Manned: * Without crew procreation * Suicide (explore and die before your time when supplies end) * One-way (outpost construction and stay till natural death) * Round-trip (return to Earth, possibly with some crew left at the outpost) * Multi-step (start to new target from the previous one) * Multigenerational * Short-range, but long (slowship) * Long-range, thus long even though fast (fastship) * Colonization 2. Type of Propulsion * Main source * All fuel on-board * Use the interstellar medium * Power from installations at Solar system * Main type * Fission * Fusion * Antimatter * Sails * Other? 3. Gravity on board * Zero or small gravity * Near-g gravity * Centrifugal (rotational) * Whole ship * Habitat ring only * Tethered sections * Acceleration * Mixed 4. Mission composition * Single ship * Multiple ships * Manned plus robotic: * Pathfinder probes * Supply ships ---------------------------------------------------------- Hoping it may help, -- Zenon From popserver Fri Jan 5 18:03:47 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["173" "Fri" "5" "January" "1996" "07:57:15" "-0800" "Ric Hedman" "HEDMARC@cellpro.cellpro.com" nil "7" "Newsletters" "^From:" "KellySt%aol.com@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com" "KellySt%aol.com@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com" "1" nil nil nil nil] nil) Return-Path: HEDMARC@cellpro.cellpro.com Received: from cellpro.com (mail.cellpro.com [198.202.28.254]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id HAA25848 for ; Fri, 5 Jan 1996 07:52:58 -0800 (PST) Received: by cryovial.cellpro.com id <44804>; Fri, 5 Jan 1996 07:56:30 -0800 X-Nvlenv-01Date-Posted: 5-Jan-1996 7:57:20 -0800; at Bothell.CellPro Priority: Urgent References: <5041ED30025C2979@-SMF-> Message-Id: <96Jan5.075630pst.44804@cryovial.cellpro.com> From: HEDMARC@cellpro.cellpro.com (Hedman, Ric) To: KellySt%aol.com@cellpro.cellpro.com Cc: hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com Subject: Newsletters Date: Fri, 5 Jan 1996 07:57:15 -0800 Well. my system has crashed once more. Please send the newsletters to this address until furture notice:: hedmarc@cellpro.cellpro.com Sorry for all the trouble. :-) Ric From popserver Fri Jan 5 18:04:11 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["140" "Fri" "5" "January" "1996" "09:29:24" "-0800" "Ric Hedman" "HEDMARC@cellpro.cellpro.com" nil "6" "e-mails" "^From:" "T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com" "Timothy van der Linden, bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com" "1" nil nil nil nil] nil) Return-Path: HEDMARC@cellpro.cellpro.com Received: from cellpro.com (mail.cellpro.com [198.202.28.254]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id JAA01557 for ; Fri, 5 Jan 1996 09:17:24 -0800 (PST) Received: by cryovial.cellpro.com id <44805>; Fri, 5 Jan 1996 09:20:50 -0800 X-Nvlenv-01Date-Posted: 5-Jan-1996 9:21:26 -0800; at Bothell.CellPro In-Reply-To: <11009A30015C2979@-SMF-> References: <11009A30025C2979@-SMF-> Message-Id: <96Jan5.092050pst.44805@cryovial.cellpro.com> From: HEDMARC@cellpro.cellpro.com (Hedman, Ric) To: T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com (Timothy van der Linden) Cc: bpvanstr%yoho.uwaterloo.ca@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com Subject: e-mails Date: Fri, 5 Jan 1996 09:29:24 -0800 Well. my system crashed again. Please forward all Newsletters to me at work until I get my home system up and running again. Thanks, Ric From popserver Fri Jan 5 23:06:51 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["567" "Fri" "6" "January" "1995" "00:04:55" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "15" "Asimov DESIGN SPACE" "^From:" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id PAA28495 for ; Fri, 5 Jan 1996 15:03:51 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA28071 (5.67b/IDA-1.5 for ); Sat, 6 Jan 1996 00:04:49 +0100 Message-Id: <199601052304.AA28071@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Asimov DESIGN SPACE Date: Fri, 06 Jan 1995 00:04:55 +0100 Timothy replies to Zenon: Yes, Zenon I can remember that message very well. To be honest, when you wrote it, I thought, nice idea, but who's gonna do it. And in fact I'm still asking myself who's going to do it? I think I will try to make a start myself, but think it won't be much fun. But I think that now we have a much better idea about the several possibilities then a year ago, so a summary may be a bit more complete. >clearing the matter and see the whole forest instead of only trees >(as Polish saying goes). We have the same saying in Dutch... Timothy From popserver Sat Jan 6 05:05:28 GMT 1996 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["3217" "Fri" "5" "January" "1996" "22:27:55" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "82" "Re: Asimov DESIGN SPACE" "^From:" "T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "Timothy van der Linden, KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id UAA18170 for ; Fri, 5 Jan 1996 20:26:42 -0800 (PST) Received: by maroon.tc.umn.edu; Fri, 5 Jan 96 22:27:56 -0600 In-Reply-To: <199601052304.AA28071@student.utwente.nl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: Timothy van der Linden cc: KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Asimov DESIGN SPACE Date: Fri, 5 Jan 1996 22:27:55 -0600 (CST) On Fri, 6 Jan 1995, Timothy van der Linden wrote: > Timothy replies to Zenon: > >clearing the matter and see the whole forest instead of only trees > >(as Polish saying goes). > > We have the same saying in Dutch... > Interesting, in english we say it the other way around: for example, "He can't see the forest for the trees" Now, for another drive proposal (you didn't possibly think I'd give up did you?) Consider the following Gedenken experiment: (inspired by actual events) you are standing on ice skates on very smooth ice (not completely frictionless, but then the ISM is not completely empty either) several hundred of your (friends?) throw snowballs at you, you catch them in a device that compresses a spring as each one is caught. Of course, as Steve teaches us, you begin to move across the ice. your friends continue to pelt you with snow balls, until you are moving with the speed of a thrown snowball (let's call it B). Halfway across the ice, you realize what will happen when you get all the way across the ice (and run out of ice) so you begin to throw your snowballs (using the energy stored in the spring) until you come to a nice stop on the far side of the ice. looking in your snowball holder, you notice that you still have some left, since the friction from the ice slowed you down a little. Of course, some of the snowballs may have melted, or small bits of snow could have rubbed off on the device, but I think you get the idea. Now, consider the the following engine design: Sol sends out a maser beam, and the "Asimov" absorbs it, turning it into electricity (let's say 80% eff) This gives the Asimov a nice 1 G accel. The energy is stored (if I knew how, I wouldn't need you guys ;) ) and later, at the halfway point, the beam from Sol stops. The "Asimov" gains some deceleration out of friction with the ISM (until you get down to about .90 C) and then releases the stored energy in the form of a maser beam generated by the "Asimov" and directed toward TC. Various transfer losses would probably leave you with some velocity even after you expended all of the stored energy. But I think that the velocity you would have left would be within the stopping range of a fusion engine. Once the antenna array was done absorbing the maser beam, it could be used for ISM drag chute, and we don't really care that it erodes away because by the time it's gone, we're below the speed where we get any useful drag. much better if a way can be found to hold the maser in a "mirrored box" and let it out with out needing conversion to electricity. I wonder, can Quantum mechanics help us here? can the wave be put in a box that allows only one harmonic to exist? Return trip is done the same way. Very simple timeline. all times relative to ship. 0 years -- leave earth 5 years -- arrive at TC, Send message informing earth. Begin assembling maser array for return trip. 5-15 yrs-- exploration / refuel / rebuild / 15 years-- maser array at TC finished. Send radio message informing earth 20 years-- arrive Sol eagerly awaiting responses. (esp. Steve and Tim -- renowned throwers of ice water) :) Kevin From popserver Sat Jan 6 05:05:32 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1866" "Fri" "5" "January" "1996" "23:37:29" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "43" "Re: Engineering Newsletter" "^From:" "rddesign@wolfenet.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl" "rddesign@wolfenet.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id UAA18725 for ; Fri, 5 Jan 1996 20:38:37 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id XAA21403; Fri, 5 Jan 1996 23:37:29 -0500 Message-ID: <960105233728_33202780@emout06.mail.aol.com> From: KellySt@aol.com To: rddesign@wolfenet.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Engineering Newsletter Date: Fri, 5 Jan 1996 23:37:29 -0500 RE: rddesign@wolfenet.com > >So what are we going to do? > >Our technology isn't quite there yet for the propulsion plant. I'm sure we >could build the rest of the ship no problem. > >The people we would like to crew the ship and maybe colonize the >new system probably won't want to go. > >We have funding problems. To small and not enought money. To large and > you couldn't get folks to decide on when to have dinner much less pay > for it. > >Where do we go? What do we do? > >Do we start in-system with projects on the moon and Mars and build > to the larger prospect of inter-steller flight? > >Alpha Centauri is half the distance. Can we make it at half the speed? Well I made my cut at it a long time ago. A fusion ship could get to Alpha C. in about 20 years, maybe 12, and a bit quicker on the flight back with fuel launchers at each end. That might be short enough to interest the public and capable people. Moneys a problem. This is going to take some heavy coin to pay for, and its not very clear why we'd do it. Colonization doesn't make any sense (why spend decades getting somewhere to do something you could do better at home), and I've never heard of people putting up this kind of money for science. That leaves exploration. A fierce public desire to send someone out there with a camera and a flag. Some reason that people will want to feel really challenged and fund a national adventure. (International isn't feasible. The costs would explode, and you'd never be able to get anything done with that many people working on it.) Early 21st century we should be making a big push into space. By mid century we should have major industrial and tourist projects, and access to effectively unlimited raw materials. Maybe we will be pumped up and full of ourselves and be in the mood for a big adventure. Kelly From popserver Sat Jan 6 17:31:46 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2403" "Fri" "6" "January" "1995" "16:20:48" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "63" "Re: Asimov DESIGN SPACE" "^From:" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id HAA05920 for ; Sat, 6 Jan 1996 07:19:38 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA19553 (5.67b/IDA-1.5 for ); Sat, 6 Jan 1996 16:20:37 +0100 Message-Id: <199601061520.AA19553@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com Subject: Re: Asimov DESIGN SPACE Date: Fri, 06 Jan 1995 16:20:48 +0100 Timothy replies to Kevin: >> >clearing the matter and see the whole forest instead of only trees >> >(as Polish saying goes). >> >> We have the same saying in Dutch... > >Interesting, in english we say it the other way around: > >for example, > >"He can't see the forest for the trees" I guess that in both cases we can't see the forest because of the trees. In fact the Dutch saying is like you wrote it. Zenon uses a negated sentence and so changed the construction of the sentence and says the same... >Consider the following Gedenken experiment: (inspired by actual events) It should be "Gedanken Experiment" (it's German) >Now, consider the the following engine design: > >Sol sends out a maser beam, and the "Asimov" absorbs it, turning it into >electricity (let's say 80% eff) This gives the Asimov a nice 1 G accel. >The energy is stored (if I knew how, I wouldn't need you guys ;) ) The only way to store so much energy would be a matter & anti-matter mixture. Talk to Kelly if you want to hear why this wouldn't work :) >much better if a way can be found to hold the maser in a "mirrored box" >and let it out with out needing conversion to electricity. I wonder, can >Quantum mechanics help us here? can the wave be put in a box that allows >only one harmonic to exist? - What would be the advantage of one harmonic? - No two particles (photons) can be in the same state, so a single harmonic isn't possible. - There is a perfect one-way mirror: a blackhole - An unperfect mirror isn't usefull at all, even the slightest unperfection will give an almost 100% loss in a small time. (The box should at best be a sphere to avoid losses in the edges and joints. So in short your method could work but we don't know a way to store the energy. Besides that, if we could store that energy, it would be better to take it with us from the start, since than there would be no efficiency losses during capturing and beaming. So if we could create anti-matter efficiently and store it, it would always be cheaper then beaming. >5-15 yrs-- exploration / refuel / rebuild / > >15 years-- maser array at TC finished. Send radio message informing earth I wonder if about 100 (wo)men can build a 10 by 10 kilometre maser array (including a power source?) in 10 years. >(esp. Steve and Tim -- renowned throwers of ice water) :) I hope I've cooled you down enough :) Timothy From popserver Sat Jan 6 20:17:51 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1096" "Sat" "6" "January" "1996" "11:06:25" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "27" "Engineering Newsletter" "^From:" "T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "Timothy van der Linden, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id KAA15051 for ; Sat, 6 Jan 1996 10:59:38 -0800 (PST) Received: from sea-ts1-p50.wolfenet.com (sea-ts1-p50.wolfenet.com [204.157.98.104]) by wolfe.net (8.7.3/8.7) with SMTP id LAA13934; Sat, 6 Jan 1996 11:06:25 -0800 (PST) Message-Id: <199601061906.LAA13934@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Engineering Newsletter Date: Sat, 6 Jan 1996 11:06:25 -0800 (PST) >Steve writes: >>KellySt@aol.com writes: >> > We could work on a Alpha Centuri flight. Thats closer to our capacity. So, let's do something about this. If the fligh time is 15 years we should be able to trim that to 8 to 10 years some how. >> >>Alpha Centauri is 4.3 lyr away. Tau Ceti is 10 lyr away. This >>is barely any difference as far as interstellar travel goes. If >>you can get to Alpha Centauri effectively, you can get to Tau >>Ceti with no more than about twice the travel time. AC is 40% of the distance of TC. I'd say that there is more than "barely any difference". On a galaxtic scale, it's nothing. To humans it makes a big difference.. Kind of like walking to Denver from Seattle instead of walking to New York. I know I could probably do it if i had to. I don't even try and fool myself that I'd want to do that. Now, is there any thing at AC worth going there for? > >It depends, if you can just reach AC with a fusion engine in 15 years, then >a round trip to TC would take at least 60 years. Not many would survive that >trip simply because of age. > >Timothy > Ric From popserver Sat Jan 6 20:17:59 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9454" "Sat" "6" "January" "1996" "14:37:56" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "242" "Re: Asimov DESIGN SPACE" "^From:" "zkulpa@lksu.ippt.gov.pl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl, zkulpa@emin08.mail.aol.com, kgstar@most.fw.hac.com" "zkulpa@lksu.ippt.gov.pl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl, zkulpa@emin08.mail.aol.com, kgstar@most.fw.hac.com" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from emout05.mail.aol.com (emout05.mail.aol.com [198.81.10.37]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id LAA16785 for ; Sat, 6 Jan 1996 11:39:25 -0800 (PST) Received: by emout05.mail.aol.com (8.6.12/8.6.12) id OAA02840; Sat, 6 Jan 1996 14:37:56 -0500 Message-ID: <960106143755_33625202@emout05.mail.aol.com> From: KellySt@aol.com To: zkulpa@lksu.ippt.gov.pl, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl cc: zkulpa@emin08.mail.aol.com, kgstar@most.fw.hac.com Subject: Re: Asimov DESIGN SPACE Date: Sat, 6 Jan 1996 14:37:56 -0500 >>>> I have an idea <<<< I mensioned to Tim that you couldn't build a ship that could carry a thousand times its own weight in fuel. True, but I forgot about staging! You start with a 1 billion ton fueled ship cluster driven by a 10 million ton engine and support structure (yeah right.). That engine is powerfull enough to push the whole mess at speed. When you burn off 95% of your weight in fuel. The ship cluster weighs 50 million tons, 20% of which is a first stage engine/structure thats WAY too powerful. You throw the first stage away and start a smaller secound stage. It weighs about 400,000 tons (about as much as 4 aircraft carriers) and can push the 40,000,000 ton ship cluster. When you burn that down to 2,000,000 tons of cluster you throw that away that stage for a 70,000 ton ship with 5-10,000 tons of drive systems. Which can use the remaining 390,000 tons of fuel to get itself into the system. stage total weight (tons) thruster pack and stage structure 1 1,000,000,000 10,000,000 2 40,000,000 400,000 3 2,000,000 70,000 ton ship with 5-10,000 tons of drive systems. This assumes a 100 to 1 thrust to weight ration for a fussion drive systems (which is questionable), and once you get where your going, coming back is out. But it would give us huge fuel ratios for relativistic flight. Possibly a multi stage fusion craft to get to the star and build a fuel launcher systems for two way flight? I'll have to think on this. > From T.L.G.vanderLinden@student.utwente.nl Fri Jan 5 11:40:02 1996 > > > > Available power sources: > > > > Fission > > Solar power > > Fusion > > Chemical > > Other? > > > > Available techniques: > > > > Beaming > > Energy storage in anti-matter > > Other? > > > > Places to go to: > > > > Tau Ceti (TC) > > Alpha Centaury (AC) > > Pluto > > > > Objectives: > > > > One way trip > > Two way trip > > > > Let's assume that all the above are possibilities. What we should do is > > calculate the size and feasability and discuss the (dis)advantages for all > > cases. We should NOT try to discard a method, but only give its advantages > > and disadvantages. > > Of course we have done a lot already, only we haven't ordered it very much. > > Maybe it is time to recapitulate our discussions. I think that we need a > > complete survey, of course every one knows a lot of it, but I think that we > > don't agree about everything yet, but we also don't know exactly what these > > differences are. > > > So we should try to come up with a kind of report. (Of course easier said > > than done) Good idea, we have pretty well argued threw everything, and a summary would be a good idea. Assuming we'ld dfo it. Several of us have suggested it. A fw said they were starting. Oh well. Using Zenons framework > Here I would like to remind about my attempt (a year ago) > to start recapitulation effort of all discussed options. > Below follows the sketch of the beginning ;-)) > of the DESIGN SPACE summary I have started then. > There should be, of course, many more aspects > listed, like target(s), life supply > (e.g., stored food/hydroponics/farming; > all crew awake/all crew hibernates(or something)/mixed, etc.), > command structure, project financing.... &c &c. > * LIT "ASIMOV" * > * Starship Design * You might have noticed I hate the name Asimov for the ship. It gives the whole project a grade school feel. I mean lets be real. This is a name that would never be acceptable to a real starship project. > The DESIGN SPACE discussed: > > 1. Type of Mission: > * Robotic > * Fly-by (no braking nor stop at target) > * Exploratory (stop at target & explore) > * Pathfinder (ahead of manned one: scouting/early warning) > * Supply (after the manned: catching on the way or at target) Fly by doesn't make much sence. If you just want to observe, you could do that just as well from here with big telescopes. Exploratory and Pathfinder have the same drive problems as the main ship, but greater funding problms and less capabilities. Pathfinder would be good as a warning scout ahead of the main ship though. > * Manned: > * Without crew procreation > * Suicide (explore and die before your time when supplies end) > * One-way (outpost construction and stay till natural death) Suicide and one way are the same. We couldn't biuld a self sustaining outpost, and wouldn't fund resupply flights forever unless there was something in it for us (or a fantastic improvement in star drives back home). NO ONE would fund a one-way flight. > * Round-trip (return to Earth, > possibly with some crew left at the outpost) About the only practical option. If we can't get them back, we woun't be allowed to send them. > * Multi-step (start to new target from the previous one) We are having a big problem even thinking how to get to one star and back. Multiples!? > * Multigenerational > * Short-range, but long (slowship) > * Long-range, thus long even though fast (fastship) > * Colonization We beat this one to death. - If its going to take you that long to get somewhere, wait for faster ships to be built. Since those ships will get there before you do anyway. - People who might want to go explore a star, certainly wouldn't settle for spending the rest of their days stuck in a ship with nothing to do. - The people who get there will have no allegence to the origional mission. In the United States about a century or two back, a lot of religious or other groups decided to go off into the wilderness and found a utopia. They eiather didn't plan and died out quick. Or they lasted about 2 generations. The grand children, didn't have their zeal, so they left, or rebuilt the city/culture along more conventional lines. Why would the grand kids bother to do our exploration for us. They never asked for this, and were never asked. I'ld bet they'ld eiather sit in the ship and wait for a followup mission to rescue them, or turn around and go home. - The people who get to the star wont be the ones you sent. They wont have the same skill mix as the first generation. They wont have any familiarity with planets, exploration, the shutles and rovers they'll need to use, etc.. - The ship would need to be much larger and better equiped to handel multiple generations (only one of which is working). Better medical, people will take more risks with their own lives then with their kids, and old people need MAJOR medical. Assuming we don't do the Canadian health care trick and just tell them their lives are no longer cost effective? - Equipment has a life expectency too folks! Usually less than 40 years. We wont be able rebuild everything in flight. So the ship will grow old and die around the crew. Even if it makes it, by the time it gets their its exploration gear will be in prety tired shape in the bay, and noone will remember how to fix it. (Sorry you can't just look it up in a VR sim.) Multi-gen is interesting in that its both technically more risky, expensive, etc.. and because of its long time lines, its certain to be a waste of time. Again, it will be certian to not get there first. Also there is a moral issue about throwing generations down a dangerous mission for no good reason. > 2. Type of Propulsion > * Main source > * All fuel on-board Not possible unless you have a very slow ship, or anti matter. Niether is very practical. Of course that assumes conventional physics. > * Use the interstellar medium We have no real idea how to, or for that matter know whats out there to use. > * Power from installations at Solar system Beamed power or fuel launchers have the advantage of offloading the need to carry the heavy fuel (and power systems) with the ship. That improves the ships power to weight ration significantly. But the systems are difficult to do, limit range, and don't seem to help us to slow down. > * Main type > * Fission > * Fusion > * Antimatter > * Sails > * Other? Fusion and anti-matter could power a ship. Microwave or laser sails could drive it. > 3. Gravity on board > * Zero or small gravity > * Near-g gravity > * Centrifugal (rotational) > * Whole ship > * Habitat ring only > * Tethered sections > * Acceleration > * Mixed I think the idea I came up with for a multi segmeny hab ring is the best. We need gravity for the crew, and the rotating hab segments will allow it to adapt to changing thrust directions. Unless the ship can operate under continuous thrust for the full flight. This seem best. > 4. Mission composition > * Single ship > * Multiple ships > * Manned plus robotic: > * Pathfinder probes > * Supply ships Given the size the main ship must be, I don't think we could afford 2. Which is a pity from a safty standpoint. A robotic pathfinder would be a good idea if it would work, but I'm dubious. A suply ship sounds a little risky. How would you like to be waiting in the target system for the next 5 years groceries. Kelly p.s. Zenon, did you CC yourself at an AmericaOnline account? (@emin08.mail.aol.com) From popserver Sat Jan 6 20:18:05 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2003" "Sat" "6" "January" "1996" "14:38:09" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "43" "Re: Asimov DESIGN SPACE" "^From:" "hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from emout05.mail.aol.com (emout05.mail.aol.com [198.81.10.37]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id LAA16860 for ; Sat, 6 Jan 1996 11:41:29 -0800 (PST) Received: by emout05.mail.aol.com (8.6.12/8.6.12) id OAA02915; Sat, 6 Jan 1996 14:38:09 -0500 Message-ID: <960106143806_33625334@emout05.mail.aol.com> From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl cc: stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Asimov DESIGN SPACE Date: Sat, 6 Jan 1996 14:38:09 -0500 > >>>>>>>>>>>>>>>>>>>>>> Now, for another drive proposal <<<<<<<<<<< > > > you are standing on ice skates on very smooth ice (not > completely frictionless, but then the ISM is not completely empty > either) several hundred of your (friends?) throw snowballs at > you, you catch them in a device that compresses a spring as each > one is caught. Of course, as Steve teaches us, you begin to move > across the ice. your friends continue to pelt you with snow balls, > until you are moving with the speed of a thrown snowball (let's > call it B). Halfway across the ice, you realize what will happen > when you get all the way across the ice (and run out of ice) so you > begin to throw your snowballs (using the energy stored in the > spring) until you come to a nice stop on the far side of the ice. -- > -- > > > Now, consider the the following engine design: > > > Sol sends out a maser beam, and the "Asimov" absorbs it, turning > it into electricity (let's say 80% eff) This gives the Asimov a > nice 1 G accel. The energy is stored (if I knew how, I wouldn't > need you guys ;) ) and later, at the halfway point, the beam from > Sol stops. The "Asimov" gains some deceleration out of friction > with the ISM (until you get down to about .90 C) and then releases > the stored energy in the form of a maser beam generated by the > "Asimov" and directed toward TC. Various transfer losses would > probably leave you with some velocity even after you expended all > of the stored energy. But I think that the velocity you would have > left would be within the stopping range of a fusion engine.--- > One alternate that was discussed prevbiously would be to throw fusion fuel snowbals to same effect as first section. But of course thats probably impractical over large distences. Your stored microwave idea is interesting, but given the huge watage flows I can't think how to store it. Unless Tim's power to antimatter conversion systems would work. Kelly From popserver Sat Jan 6 20:18:11 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["164" "Sat" "6" "January" "1996" "14:52:06" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "9" "Re: Engineering Newsletter" "^From:" "rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: KellySt@aol.com Received: from mail02.mail.aol.com (mail02.mail.aol.com [152.163.172.66]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id LAA17378 for ; Sat, 6 Jan 1996 11:52:54 -0800 (PST) Received: by mail02.mail.aol.com (8.6.12/8.6.12) id OAA03346; Sat, 6 Jan 1996 14:52:06 -0500 Message-ID: <960106145205_84893438@mail02.mail.aol.com> From: KellySt@aol.com To: rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl cc: hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Sat, 6 Jan 1996 14:52:06 -0500 to: Rick >> Now, is there any thing at AC worth going there for? Is there anything in Tau C? You got a problem with multiple star systems or something? Kelly From popserver Sat Jan 6 21:24:31 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1250" "Sat" "6" "January" "1996" "15:21:48" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "32" "Re: Engineering Newsletter" "^From:" "KellySt@aol.com, rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "KellySt@aol.com, rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com" "1" nil nil nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id NAA21657 for ; Sat, 6 Jan 1996 13:20:37 -0800 (PST) Received: by maroon.tc.umn.edu; Sat, 6 Jan 96 15:21:49 -0600 In-Reply-To: <960106145205_84893438@mail02.mail.aol.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: KellySt@aol.com cc: rddesign@wolfenet.com, T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com Subject: Re: Engineering Newsletter Date: Sat, 6 Jan 1996 15:21:48 -0600 (CST) On Sat, 6 Jan 1996 KellySt@aol.com wrote: > to: Rick > > > >> Now, is there any thing at AC worth going there for? > > Is there anything in Tau C? You got a problem with multiple star systems or > something? > One reason to go to AC, would be to see if there are any planets, how far out they are, and so forth. The dynamicists tell us that we can expect them to be close in to one of the stars, or way out from both (all three?) but I've not seen anything that says just how far out or how close in. The opportunities for advancing our knowledge about multi-stared systems might just make the trip worthwhile. we could also see just how much comprhensible noise our star system makes. are we letting out a big Neon sign that blinks and says "Eat at Sol's", or are we such tiny whos that only Horton can hear us? (from a Dr. Suess book called "Horton hears a Who" for our non-native english members) As for the name "Asimov", I was under the impression that it was decided by vote, (although it now seems that we do it by rote) Anyway, you'll all be delighted to know that I now have a descent calculator again, a TI-92 $231.00 at the Univ. Bookstore. a thousand curses on the miscreant who stole my TI-85 >:-( Kevin From popserver Sat Jan 6 22:42:06 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4350" "Sat" "6" "January" "1996" "14:01:06" "-0800" "Steve VanDevender" "stevev@efn.org" nil "84" "Re: Asimov DESIGN SPACE" "^From:" "hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "Kevin C Houston, Timothy van der Linden, KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com" "1" nil nil nil nil] nil) Return-Path: stevev@tzadkiel.efn.org Received: from tzadkiel.efn.org (stevev@tzadkiel.efn.org [198.68.17.19]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id OAA23388; Sat, 6 Jan 1996 14:00:57 -0800 (PST) Received: (from stevev@localhost) by tzadkiel.efn.org (8.7.3/8.7.3) id OAA10967; Sat, 6 Jan 1996 14:01:06 -0800 Message-Id: <199601062201.OAA10967@tzadkiel.efn.org> In-Reply-To: References: <199601052304.AA28071@student.utwente.nl> From: Steve VanDevender To: Kevin C Houston Cc: Timothy van der Linden , KellySt@aol.com, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Asimov DESIGN SPACE Date: Sat, 6 Jan 1996 14:01:06 -0800 Kevin C. Houston writes: > [ . . . ] > > Now, consider the the following engine design: > > Sol sends out a maser beam, and the "Asimov" absorbs it, turning it into > electricity (let's say 80% eff) This gives the Asimov a nice 1 G accel. > The energy is stored (if I knew how, I wouldn't need you guys ;) ) and > later, at the halfway point, the beam from Sol stops. The "Asimov" gains > some deceleration out of friction with the ISM (until you get down to > about .90 C) and then releases the stored energy in the form of a maser > beam generated by the "Asimov" and directed toward TC. Various transfer > losses would probably leave you with some velocity even after you > expended all of the stored energy. But I think that the velocity you > would have left would be within the stopping range of a fusion engine. > Once the antenna array was done absorbing the maser beam, it could be > used for ISM drag chute, and we don't really care that it erodes away > because by the time it's gone, we're below the speed where we get any > useful drag. > > [ . . . ] > > eagerly awaiting responses. > > (esp. Steve and Tim -- renowned throwers of ice water) :) > > Kevin You'll probably die of shock, Kevin, but this idea, at least in concept, could actually work. Collecting and storing the immense energy required is likely to be almost impossible, but assuming that a method existed, this doesn't seem to violate the laws of physics. I'd like to present a similar idea framed in terms ofw a laser and a sheet of "slow glass" -- a material that was the main gimmick in a few science fiction stories by an author whose name I can't remember right now (darn it). Slow glass transmits light, but with a long time delay between when it comes in one side and goes out the other. In the stories, it was used for things like scenery windows -- a sheet of slow glass was set in a field for a few years, then put on the wall of a house, where it would release the years of scenery. Let's pick a sheet of slow glass that has a year-long delay between when it absorbs light on one side and re-emits it on the other. If we shine a laser at a sheet of slow glass, it will effectively appear to absorb the laser light, and the light's momentum, for the first year of its proper time. At the end of that year of proper time for the glass, the laser is turned off, and the absorbed laser light is emitted from the other side of the glass. Light continues to be emitted for another year of proper time for the glass, until all of the laser light absorbed has been emitted. At least to the first analysis, the glass must pick up momentum from the laser beam while it is absorbing the photons, and accelerates for as long as the laser is beamed at it. Then, when the light begins coming out the other side, the glass loses that momentum and decelerates. The end result seems like it ought to be that the glass ends up with some amount of spatial displacement from its original position, and the laser light passes through effectively unchanged, so that energy and momentum are conserved throughout. However, assuming a laser that emits constant power in its rest frame, the light intensity from the laser seen by the slow glass won't be constant. As the slow glass accelerates, the incident power from the laser will decrease from doppler shifting. Getting the glass to accelerate to high relativistic speeds will also cause the system of the glass and the photons absorbed to that point to increase significantly in mass (this isn't the same as what Timothy calls "relativistic mass increase" -- why?). So I'm a little troubled about the overall physics -- if the glass emits exactly the light it saw, then at the end of the first year of its proper time, if it emits the same light it saw at the beginning of the year, an observer in front of it would see that light tremendously blue-shifted if the glass was accelerated to high relativistic speeds. On the other hand, by the end of the second year of proper time of the glass, the light it emits is the very red-shifted light it was absorbing just before the laser turned off. I'm not sure, without doing the math, whether this comes out such that the energy emitted during the second year is the same as the energy absorbed during the first year. From popserver Sat Jan 6 23:17:38 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["591" "Sat" "6" "January" "1996" "15:17:58" "-0800" "rddesign@wolfenet.com" "rddesign@wolfenet.com" nil "22" "Re: Engineering Newsletter" "^From:" "KellySt@aol.com, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "KellySt@aol.com, KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl" "1" nil nil nil nil] nil) Return-Path: rddesign@wolfenet.com Received: from wolfe.net (mail1.wolfe.net [204.157.98.11]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id PAA26461 for ; Sat, 6 Jan 1996 15:11:31 -0800 (PST) Received: from sea-ts1-p50.wolfenet.com (sea-ts1-p50.wolfenet.com [204.157.98.104]) by wolfe.net (8.7.3/8.7) with SMTP id PAA26114; Sat, 6 Jan 1996 15:17:58 -0800 (PST) Message-Id: <199601062317.PAA26114@wolfe.net> X-Sender: rddesign@gonzo.wolfenet.com X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: rddesign@wolfenet.com To: KellySt@aol.com Cc: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, T.L.G.vanderLinden@student.utwente.nl Subject: Re: Engineering Newsletter Date: Sat, 6 Jan 1996 15:17:58 -0800 (PST) >to: Rick > > >>> Now, is there any thing at AC worth going there for? > >Is there anything in Tau C? You got a problem with multiple star systems or >something? > >Kelly > I have no problem with multi-star systems but will they support planets that would be stable for life? And you are right, Is there anything at TC worth going to either. The problems is were we live, and probably true for space as a whole, with few stars "close" to us. The problem of living in a spur of a sprial arm, kind of out of the mainstream. Like being in a town that the Intestate jogged around. :-) Ric From popserver Sun Jan 7 03:17:03 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4078" "Sat" "7" "January" "1995" "01:51:26" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "91" "Re: Asimov DESIGN SPACE" "^From:" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id QAA01997 for ; Sat, 6 Jan 1996 16:50:18 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10800 (5.67b/IDA-1.5 for ); Sun, 7 Jan 1996 01:51:20 +0100 Message-Id: <199601070051.AA10800@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu Subject: Re: Asimov DESIGN SPACE Date: Sat, 07 Jan 1995 01:51:26 +0100 Timothy replies to Kelly: >stage total weight (tons) thruster pack and stage structure >1 1,000,000,000 10,000,000 >2 40,000,000 400,000 >3 2,000,000 70,000 ton ship > with 5-10,000 tons of > drive systems. > >This assumes a 100 to 1 thrust to weight ration for a fussion drive systems >(which is questionable), and once you get where your going, coming back is >out. But it would give us huge fuel ratios for relativistic flight. > Possibly a multi stage fusion craft to get to the star and build a fuel >launcher systems for two way flight? I'll have to think on this. I assumed that we could build a variable thrust engine, but for weight-savings staging may be better. I think that staging would not solve a more fundamental problem: Pressure One can see the engine as a force pressing on the back of the ship. We want a certain acceleration a. The heavier the ship gets, the bigger the force that is needed to get that acceleration (F=m*a). But assuming the backside of the ship stays about the same, the pressure (p=F/Area) gets bigger and bigger. So for a certain weight of the ship the pressure may become to big for any material to hold. (The backside of the ship is a loose expression, in fact it would be the support beams that connect the ship and the engine) >> * LIT "ASIMOV" * >> * Starship Design * > >You might have noticed I hate the name Asimov for the ship. It gives the >whole project a grade school feel. I mean lets be real. This is a name that >would never be acceptable to a real starship project. I never liked it much either, I guess the vote was done by passer-by-ers on the Web. I can recal that I added the optimistic name 'New Eden' :) What did you vote Kelly? >> * Manned: >> * Without crew procreation >> * Suicide (explore and die before your time when supplies end) >> * One-way (outpost construction and stay till natural death) > >Suicide and one way are the same. We couldn't biuld a self sustaining >outpost, and wouldn't fund resupply flights forever unless there was >something in it for us (or a fantastic improvement in star drives back home). > NO ONE would fund a one-way flight. I don't agree with you on that (yet?), I will expect an answer on my letter of 01-05 10:55. >> * Use the interstellar medium > >We have no real idea how to, or for that matter know whats out there to use. There is just too little, unless we can scoop an area with a 1000 km radius. >> * Power from installations at Solar system > >Beamed power or fuel launchers have the advantage of offloading the need to >carry the heavy fuel (and power systems) with the ship. That improves the >ships power to weight ration significantly. But the systems are difficult to >do, limit range, and don't seem to help us to slow down. Also they have a not so good efficiency. (A big part of the beam just flies along the ship without being used.) >> 3. Gravity on board > >I think the idea I came up with for a multi segmeny hab ring is the best. We >need gravity for the crew, and the rotating hab segments will allow it to >adapt to changing thrust directions. Unless the ship can operate under >continuous thrust for the full flight. This seem best. You would always need the rotating rings, because in the time that you spend at TC you don't have acceleration because of engine-thrust. >> 4. Mission composition > >Given the size the main ship must be, I don't think we could afford 2. Which >is a pity from a safty standpoint. A robotic pathfinder would be a good idea >if it would work, but I'm dubious. > >A suply ship sounds a little risky. How would you like to be waiting in the >target system for the next 5 years groceries. The idea of supply ships is to send them first and wait for them to arrive savely, unfortunately that would take 20 years from their launch. No a good way for food. Timothy From popserver Sun Jan 7 03:17:06 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1118" "Sat" "7" "January" "1995" "01:51:37" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "25" "Re: Engineering Newsletter" "^From:" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id QAA02001 for ; Sat, 6 Jan 1996 16:50:21 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10812 (5.67b/IDA-1.5 for ); Sun, 7 Jan 1996 01:51:31 +0100 Message-Id: <199601070051.AA10812@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu Subject: Re: Engineering Newsletter Date: Sat, 07 Jan 1995 01:51:37 +0100 !Warning this letter contains no important info! Timothy replies to Kevin: >One reason to go to AC, would be to see if there are any planets, how far >out they are, and so forth. The dynamicists tell us that we can expect >them to be close in to one of the stars, or way out from both (all three?) >but I've not seen anything that says just how far out or how close in. >The opportunities for advancing our knowledge about multi-stared systems >might just make the trip worthwhile. we could also see just how much >comprhensible noise our star system makes. are we letting out a big Neon >sign that blinks and says "Eat at Sol's", or are we such tiny whos that >only Horton can hear us? (from a Dr. Suess book called "Horton hears a >Who" for our non-native english members) And what is "a Who"? >Anyway, you'll all be delighted to know that I now have a descent >calculator again, a TI-92 $231.00 at the Univ. Bookstore. a thousand >curses on the miscreant who stole my TI-85 >:-( So now all you have to do is learn where what function can be found under these "10-function" buttons? Timothy From popserver Sun Jan 7 03:17:07 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3401" "Sat" "7" "January" "1995" "01:51:42" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "66" "Re: Asimov DESIGN SPACE" "^From:" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu" "1" nil nil nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id QAA02017 for ; Sat, 6 Jan 1996 16:50:30 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA10820 (5.67b/IDA-1.5 for ); Sun, 7 Jan 1996 01:51:37 +0100 Message-Id: <199601070051.AA10820@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu Subject: Re: Asimov DESIGN SPACE Date: Sat, 07 Jan 1995 01:51:42 +0100 Timothy replies to Steve: >I'd like to present a similar idea framed in terms ofw a laser and >a sheet of "slow glass" -- a material that was the main gimmick >in a few science fiction stories by an author whose name I can't >remember right now (darn it). Slow glass transmits light, but >with a long time delay between when it comes in one side and goes >out the other. In the stories, it was used for things like >scenery windows -- a sheet of slow glass was set in a field for a >few years, then put on the wall of a house, where it would >release the years of scenery. The slowest glass would be diamond with a speed of light 2.4 times slower than vacuum. But maybe there are other material with a higher refractive index for other wavelengths. >At least to the first analysis, the glass must pick up momentum >from the laser beam while it is absorbing the photons, and >accelerates for as long as the laser is beamed at it. Then, when >the light begins coming out the other side, the glass loses that >momentum and decelerates. The end result seems like it ought to >be that the glass ends up with some amount of spatial >displacement from its original position, and the laser light >passes through effectively unchanged, so that energy and momentum >are conserved throughout. This is a really fascinating idea, I wish I had thought of it. >However, assuming a laser that emits constant power in its rest >frame, the light intensity from the laser seen by the slow glass >won't be constant. As the slow glass accelerates, the incident >power from the laser will decrease from doppler shifting. >Getting the glass to accelerate to high relativistic speeds will >also cause the system of the glass and the photons absorbed to >that point to increase significantly in mass (this isn't the same >as what Timothy calls "relativistic mass increase" -- why?). Yes why, I don't understand, the glass is just a fast moving mass, so it will increase in mass due to a higher velocity. Of course the photons add some extra weight (m=Ephoton/c^2) >So I'm a little troubled about the overall physics -- if the glass >emits exactly the light it saw, then at the end of the first year >of its proper time, if it emits the same light it saw at the >beginning of the year, an observer in front of it would see that >light tremendously blue-shifted if the glass was accelerated to >high relativistic speeds. On the other hand, by the end of the >second year of proper time of the glass, the light it emits is >the very red-shifted light it was absorbing just before the laser >turned off. I'm not sure, without doing the math, whether this >comes out such that the energy emitted during the second year is >the same as the energy absorbed during the first year. As far as I can tell this is indeed what happens the first light that comes out is blue shifted. But the last light that comes out isn't more red-shifted than when it entered, because when the last light comes out the glass isn't moving anymore. Of course this slow glass should be very "clear" otherwise most of the light would be really absorbed before it could leave. Now that we are talking about slow-glass, did you know that you could make a photon stand still relative to you. Just shoot it in a bar of glass, then move the glass with about 0.7c in the opposite direction. The photon will then not move relative to you. Timothy From popserver Sun Jan 7 18:02:49 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["728" "Sun" "7" "January" "1996" "08:23:28" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "24" "Re: Engineering Newsletter" "^From:" "T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com" "Timothy van der Linden, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com" "1" nil nil nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id GAA00900 for ; Sun, 7 Jan 1996 06:22:18 -0800 (PST) Received: by maroon.tc.umn.edu; Sun, 7 Jan 96 08:23:28 -0600 In-Reply-To: <199601070051.AA10812@student.utwente.nl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: Timothy van der Linden cc: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hedmarc@cellpro.cellpro.com Subject: Re: Engineering Newsletter Date: Sun, 7 Jan 1996 08:23:28 -0600 (CST) On Sat, 7 Jan 1995, Timothy van der Linden wrote: > >only Horton can hear us? (from a Dr. Suess book called "Horton hears a > >Who" for our non-native english members) > > And what is "a Who"? read the book ;) I wouldn't want to spoil the end for you. :) > > >Anyway, you'll all be delighted to know that I now have a descent > >calculator again, a TI-92 $231.00 at the Univ. Bookstore. a thousand > >curses on the miscreant who stole my TI-85 >:-( > > So now all you have to do is learn where what function can be found under > these "10-function" buttons? > yeah, and I'm really upset that the physical constants and the metric conversions aren't on the TI-92, that was half the value of the TI-85 Kevin From popserver Mon Jan 8 19:58:44 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5900" "Mon" "8" "January" "1996" "20:55:12" "+0100" "Zenon Kulpa" "zkulpa@lksu.ippt.gov.pl" nil "145" "Re: Asimov DESIGN SPACE" "^From:" "hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, kgstar@most.fw.hac.com, zkulpa@sunet.se" "hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, kgstar@most.fw.hac.com, zkulpa@sunet.se" "1" nil nil nil nil] nil) Return-Path: zkulpa@lksu.ippt.gov.pl Received: from sunic.sunet.se (sunic.sunet.se [192.36.125.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id LAA23486 for ; Mon, 8 Jan 1996 11:52:45 -0800 (PST) Received: from lksu.ippt.gov.pl by sunic.sunet.se (8.6.8/2.03) id UAA02886; Mon, 8 Jan 1996 20:53:55 +0100 Received: from zmit1.ippt.gov.pl by lksu.ippt.gov.pl (4.1/SMI-4.1) id AA26153; Mon, 8 Jan 96 20:55:12 +0100 Organization: Institute of Fundamental Technological Research Address: Swietokrzyska 21, 00-049 Warszawa, POLAND Message-Id: <9601081955.AA26153@lksu.ippt.gov.pl> From: zkulpa@lksu.ippt.gov.pl (Zenon Kulpa) To: hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, kgstar@most.fw.hac.com Cc: zkulpa@sunet.se Subject: Re: Asimov DESIGN SPACE Date: Mon, 8 Jan 96 20:55:12 +0100 > From KellySt@aol.com Sat Jan 6 20:43:10 1996 > [...] > Good idea, we have pretty well argued threw everything, and a summary would > be a good idea. Assuming we'ld dfo it. Several of us have suggested it. A > fw said they were starting. Oh well. Using Zenons framework > > > Here I would like to remind about my attempt (a year ago) > > to start recapitulation effort of all discussed options. > > Below follows the sketch of the beginning ;-)) > > of the DESIGN SPACE summary I have started then. > > There should be, of course, many more aspects > > listed, like target(s), life supply > > (e.g., stored food/hydroponics/farming; > > all crew awake/all crew hibernates(or something)/mixed, etc.), > > command structure, project financing.... &c &c. > > > * LIT "ASIMOV" * > > * Starship Design * > > You might have noticed I hate the name Asimov for the ship. It gives the > whole project a grade school feel. I mean lets be real. This is a name that > would never be acceptable to a real starship project. > The name arised from the vote by LIT members. I did not vote - I missed the deadline... My proposal would be different, though Asimov-like: "FarStar". However, on second thoughts, it should possibly be changed to "NearStar", to be more real...;-)). Acceptable for the real thing or not, it seems good enough as our "working name" in discussions. When starting to build the real thing :-) we can announce the name competition again... Concerning my "preliminary sketch of the beginning of the Design Space topics listing" :-)), I think we should first finish the (well ordered & structured) listing of the topics in the Design Space instead of arguing again over these few topics I have listed which were over-argued back and forth already... And the rationale for the listing is NOT to list options which we (who are we, anyway?) AGREED upon (I am afraid there are a few, if any, of them - even the name semms to be still disputable...), but to list ALL the options proposed, in a structured way, to give us insight about the full range of possibilities and their interdependence (something like the list obtained after the first stage of a brainstorming session). Such a listing may be then used as a structuring device for collecting the results of/positions taken during the discussion, showing, e.g., the holes in the arguments or (im)possibilities that were missed somehow, etc. In this way we may come at the only(!? - any other ideas?) useful and READABLE (in the finite time left us... ;-)) summary of the discussion and progress made so far. Without this, I am afraid further discussion would be a waste of time: as many of you complain, we are already either going around in circles, endlessly repeating the arguments and ideas that just happen old enough to be forgotten by most of the remaining participants, or are trying to devise more and more outlandish SF ideas without knowing whether they are really necessary (or whether they were not discussed a year ago...). I know it may be boring, such compilation and structuring of topics, but it is inevitable if the whole LIT affair is to have any further sense. I have made a beginning - let someone else adds a few more topics to the list (from his favourite domain) - we will then shortly discuss and refine the composition of this additional fragment of the list (NOT discussing the pro/contra of the topics on it - THAT was discussed upon already!), then go to the next few... Thus, Kellys discussion of the options on my list is rather off (current) topic - there are many arguments pro/contra the options listed (as for me, I have the opposite opinion to at least some arguments given by Kelly in his letter), but this is no time to repeat them - first, we should list all options discussed, then recapitulate shortly the previous arguments (the even MORE BORING part of the job... ;-)) using the list as a Table of Contents, and then start arguing again for the topics we find not (over-)discussed yet satisfactorily. Thus, despite the (AAAFFFULLL!) itching, I try to refrain from arguing with Kelly's opinions on the topics I listed. Ohhh my, except that one: ;-O ------------------------ > > * Manned: > > * Without crew procreation > > * Suicide (explore and die before your time when supplies end) > > * One-way (outpost construction and stay till natural death) > > Suicide and one way are the same. > Kelly, try to be logical. They are NOT the same (for short explanation - see inside brackets above). > We couldn't biuld a self sustaining > outpost, > If so, we couldn't build the (tens-of-years)-self sustaining space ship, either... > and wouldn't fund resupply flights forever > You assume the outpost crew will live forever? [see above]. And with the presently foreseable technology, the return flight will last just around the life expectancy of the outpost crew (oh, let add some 10 yers or so); thus the return will have almost only one sense - to bury the crew bones in the Earth grave (rather than in Space...). Or either we should assume "a fantastic improvement in star drives" (your words, Kelly...). No question in this case - we should plan a round-trip mission (but, I am sure, quite a number of the crew will want to stay back at the outpost anyway - I would, for that matter). [...] > NO ONE would fund a one-way flight. > Did you ask EVERYone, so you are so cock-sure about that "NO ONE" thing? ------------------------------------------ Enough, Zenon, do not indulge yourself in the pleasure of arguing with Kelly, against your own advice... > p.s. > Zenon, did you CC yourself at an AmericaOnline account? > (@emin08.mail.aol.com) > I do not think so. At least I am not aware of having any contacts with AOL. Why do you ask? -- Zenon From popserver Mon Jan 8 21:55:47 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2399" "Mon" "8" "January" "1996" "16:51:58" "-0500" "David Levine" "David@interworld.com" nil "85" "Re: Asimov DESIGN SPACE" "^From:" "T.L.G.vanderLinden@student.utwente.nl, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu, david@interworld.com" "Timothy van der Linden, KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu, david@interworld.com" "1" nil nil nil nil] nil) Return-Path: David@interworld.com Received: from www.interworld.com (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id NAA02271 for ; Mon, 8 Jan 1996 13:51:30 -0800 (PST) Received: from hal ([165.254.130.90]) by www.interworld.com (post.office MTA v1.9.1 ID# 0-11464) with SMTP id AAA259; Mon, 8 Jan 1996 16:55:40 -0500 Message-ID: <30F191FE.4573@interworld.com> Organization: InterWorld, Really Cool Stuff Division X-Mailer: Mozilla 2.0b3 (WinNT; I) MIME-Version: 1.0 References: <199601070051.AA10800@student.utwente.nl> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: David@interworld.com (David Levine) To: Timothy van der Linden CC: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hedmarc@cellpro.cellpro.com, hous0042@maroon.tc.umn.edu, david@interworld.com Subject: Re: Asimov DESIGN SPACE Date: Mon, 08 Jan 1996 16:51:58 -0500 Timothy van der Linden wrote: > >> * LIT "ASIMOV" * > >> * Starship Design * > > > >You might have noticed I hate the name Asimov for the ship. It gives the > >whole project a grade school feel. I mean lets be real. This is a name that > >would never be acceptable to a real starship project. > > I never liked it much either, I guess the vote was done by passer-by-ers on > the Web. I can recal that I added the optimistic name 'New Eden' :) > What did you vote Kelly? > Obviously, the ship can be called anything - that's the least of the worries. In the interest of accuracy, though, here's how the name was decided: (and again, remember, you guys are doing the work now, if you wish to rename it, please, by all means...) There was a two month period in which names were accepted for submission, and a one month voting period. Only 15 people voted. Internet apathy at its best. First choice got 3 points, second 2 points, and third 1 point. While many of the names on the list are no longer familiar, some of these people were pretty active at the time, and at least three were "faculty", whatever that meant. I can't remember what I voted for, except I think "Albert Einstein" was one of my favorites. People Who Voted: ----------------- Jason Patten Calvin Li Chris Dolan Robin Chapman Scott Dawson Elisa Derickson Timothy van der Linden Eric Moore Doug Lampert Jeff Balcerski Ges Seger Chad Barb David Levine Don Flint Kellie Miller Top Four Names: --------------- Asimov - 13 points Albert Einstein - 9 points Intrepid - 8 points Enterprise - 5 points Last Place: ----------- Bradbury - 1 point Raw Data: --------- Albert Einstein ********* Ambassador ** Ancient Mariner *** Asimov ************* Bradbury * Brain of Pooh ** Brave Endeavour *** Brave New World ** Cassandra's Redemption *** Challenger **** Copernicus **** Eagle ** Emissary *** Enterprise ***** Far Reach ** Intrepid ******** Galileo **** Kepler *** Lady Galadril **** New Eden *** Star Hack ** Star Tramp ** Thunder Road *** Yamato *** From popserver Mon Jan 8 22:56:09 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["226" "Mon" "8" "January" "1996" "14:27:12" "-0800" "Ric Hedman" "HEDMARC@cellpro.cellpro.com" nil "7" "My e-mails" "^From:" "david%InterWorld.com@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com, T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com" "david%InterWorld.com@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com, Timothy van der Linden" "1" nil nil nil nil] nil) Return-Path: HEDMARC@cellpro.cellpro.com Received: from cellpro.com (mail.cellpro.com [198.202.28.254]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id OAA03834 for ; Mon, 8 Jan 1996 14:15:00 -0800 (PST) Received: by cryovial.cellpro.com id <44801>; Mon, 8 Jan 1996 14:18:58 -0800 X-Nvlenv-01Date-Posted: 8-Jan-1996 14:19:42 -0800; at Bothell.CellPro Priority: Urgent References: <2449F130025C2979@-SMF-> Message-Id: <96Jan8.141858pst.44801@cryovial.cellpro.com> From: HEDMARC@cellpro.cellpro.com (Hedman, Ric) To: david%InterWorld.com@cellpro.cellpro.com, hous0042%maroon.tc.umn.edu@cellpro.cellpro.com, zkulpa%zmit1.ippt.gov.pl@cellpro.cellpro.com, jim%bogie2.bio.purdue.edu@cellpro.cellpro.com, RUSSESS@cellpro.cellpro.com, stevev%efn.org@cellpro.cellpro.com, KellySt%aol.com@cellpro.cellpro.com, T.L.G.vanderLinden%student.utwente.nl@cellpro.cellpro.com (Timothy van der Linden) Subject: My e-mails Date: Mon, 8 Jan 1996 14:27:12 -0800 Thank you one and all for assiting me during the inconvenence with the LIT newsletter mailings. I can now access e-mail from home again. Please send future newsletters to the: rddesign@wolfenet.com address. Thank you, Ric From popserver Mon May 1 19:28:35 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["10192" "Mon" "1" "May" "1995" "13:02:38" "-0500" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "197" "Re: relativistic acceleration stuff" "^From:" nil nil "5" nil "relativistic acceleration stuff" nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA10241; Mon, 1 May 95 11:02:39 PDT Received: by maroon.tc.umn.edu; Mon, 1 May 95 13:02:41 -0500 Reply-To: Kevin C Houston In-Reply-To: <199504300023.RAA23296@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII X-UIDL: 799356346.067 From: Kevin C Houston Sender: Kevin C Houston To: Steve VanDevender Subject: Re: relativistic acceleration stuff Date: Mon, 1 May 1995 13:02:38 -0500 (CDT) On Sat, 29 Apr 1995, Steve VanDevender wrote: > Here I'm keeping things simple by measuring both mass and energy > in units of mass. What this means, though, is that to accelerate > 1 kg of mass to 0.9996 c, you need to convert a additional 35 kg > of mass completely to energy to apply to the original unit of > reaction mass. That's some power requirement! In the most ideal > case, you have to carry 35 times as much fuel as reaction mass to > get an exhaust velocity of 0.9996 c, _or_ receive that quantity > of energy from an outside source. For your example of wanting to > have 0.011645 kg accelerated to that velocity, the total power > required is 3.701E16 joules; therefore you have to receive beamed > power of 3.701E16 W in order to maintain a rate of 0.011645 kg of > reaction mass accelerated to 0.9996 c every second. This number (3.7 E+16 W) agrees quite well with my results. > > This is complicated further by redshifting; as you reach higher > and higher velocities the effective power from the beam > decreases. In order for the ship to maintain a consistent 10 > m/s^2 acceleration in its frame, the beamer has to continually > increase its power. > I looked at the redshifting problem, and decided that the sensible thing to do is decrease your acceleration as you approach light speed. in the ship's frame, the amount of time spent accelerating less than 10 m/s^2 is only about a week, and if the power starts out slightly higher than needed, then there is no shortfall at midpoint. > If you really could maintain 1 g acceleration in the ship frame, > you run into an even worse problem with getting beamed power -- > during the first year of acceleration, you watch the beam > decrease in power to effectively 0! If you continue the > acceleration using stored fuel on the ship, the beamer is > completely inaccessible to you -- your velocity approaches an > asymptote with slope c that intersects the origin at about t = 1 > yr. You are completely unable to receive anything from the other > side of that asymptote, or in other words power transmitted after > about the first year of beamer (Earth) time; it's very much like > a black hole event horizon opens up 1 lyr behind you. Of course, > in reality maintaining continuous acceleration indefinitely is > pretty much impossible, but you are going to have to expect that > you won't get much beamed power once you get very close to c. > Again, by decreasing your acceleration near the midpoint, you can avoid some of this problem by not getting too close to c. The rest of the problem dissappears (for me) upon noting that the beamer only has to beam about 1.5 years anyway, after that, any light that is beamed to T.C. will get there _after_ we've come to rest. also, the time dialation effect would keep _power_ (not energy) essentially constant wouldn't it? by that I mean that while red-shifted light would be falling on the dipoles, the amount that would fall per second would increase (beacuse our seconds would get longer). Also, because we have to decelerate at some point, power sent from earth after 1 year would still reach us and do us some good, when we are approaching T.C. > Here's a relativity puzzler that you might find enlightening (I > came up with it while I was thinking about these problems, and > while I haven't made a detailed analytical solution, I'm pretty > sure that I know what the answer is): You have two perfect > mirrors facing each other, exactly parallel. You create a > coherent beam of photons that will bounce continually back and > forth between the mirrors. The photons have momentum (and > therefore energy) p; the two identical mirrors each have mass m. > By reflecting off the mirrors, the photons will gradually > accelerate the mirrors, causing them to move apart; what are the > final velocities of the mirrors, and what happens to the beam of > photons? Without going into a detailed analysis, I would say that as the mirrors begin to accelerate, the reflected light would begin falling in energy (wavelength) and that the final speed would depend on the amount of energy in the beam of light and the mass of the mirrors; the final speed should be less than c, unless you have infinite time in which to accelerate. > There are several reasons why I think that a mass-based thruster > may be more advantageous than a photon-based one: > > 1) slowing down. You need a sail three times larger than otherwise > needed, in order to have the incident photons be in the right > direction. > > I don't know that I have the _Flight of the Dragonfly_ book, but > I do have the _Rocheworld_ serial that appeared in Analog, which > I think was the original publication of the book. I just looked > over it for a bit, and it appears to use an idea I hadn't > originally been thinking about, which is to use a sail initially > to accelerate, then to split the sail and use part of it to > reflect and focus energy backwards to the remaining part to > decelerate. I didn't see any hard figures leap out at me other > than the sail sizes, though; those agree with the figures you > imply. > This is one of the monsters in the light sail senario, "Dragonfly" weighs 10,000 tons (inner sail and 3000 tons payload) with a 300 Km dia inner sail, and a 1000 Km outer sail (outer sail alone weighs 72,000 tons) it acelerates at .01g for twenty years, and decelerates at .1 g for 2 years. I meant to say that it'd need three times the _energy_ for deceleration. I now see, that these sail sizes are smaller than the MARS (10000 Km) but the payload size of the MARS is much bigger (2,000,000) tons and we are going to accelerate at 1 Sg, so we wont have any medical problems (and we get that wonderful time dialation) > 2) drag and radiation at relativistic velocity. the best acceleration > is going to be one grav or slightly above, near turnaround point, we > get up to .999999....... of C (you pays your money and you takes your > decimal points) however, this is just where drag starts to play havoc > with your sail. the on coming protons (stripped hydrogens) _appear_ > much more massive than normal (of course). but because of > time-dialation effects, you encounter many more of them in a ship's > "day" than you would otherwise find in interstellar space. near > turnaround, we are going to pass through a volume of space of a > light-year length in around three days. if you have a huge sail, then > the force of the interstellar gale will slow you down fast! > > It's not that the incoming protons are more massive. It's that > they have more energy and momentum. This is kind of a picky > distinction, but at my current level of understanding it is > important. What I mean by saying that their mass has increased, is to say that the momentum and velocity dont add up with the rest mass. p=M*V but the momentum of the oncoming hydrogen coming at near light speed is not consistent with an atomic weight of one AMU it is consistent with a particle of mass of 1 AMU/sqrt(1-v^2/c^2) > > You could also blame the increased incidence of incoming protons > on Lorentz contraction; you get the same result. > Yes I know. > As far as I know, if the beamed power is coming in at radio > frequencies (weren't we talking about a microwave beamer?), the > reflector doesn't have to be one continuous sheet, like it would > be if you were using a visible-light laser. well, even the visible light sail that Foreward uesed, had tiny holes in it that were smaller than the wavelength of laser light ( but when the hero tripled the wavelength of light, (to get around a fensel zone lens that had not gotten enough federal funding), he forgot to mention whether the one-third sized wave lengths would passs through the sail Hee Hee Hee. > > 3)sail size. The sail size needed to accelerate at 1 grav is > horrendous, even for a "small" ship. See Robert L. Foreward's "Flight > of the Dragonfly" (if you haven't already.) > > Again, I don't see why a reflective sail is going to be any > larger than the antenna/collector needed to absorb the energy > rather than reflect it. retro reflection > > What I'm arguing is that if you are relying on beamed power to > reduce your mass load, then you are better off reflecting the > power to get thrust rather than using it to accelerate reaction > mass, at least for the acceleration phase of your trip. Here's > why: > > You don't discard all the reaction mass at once, as in the ideal > equation I derived earlier. In the early phases of the trip, you > are using your reaction mass to accelerate your remaining > reaction mass in addition to the payload mass. So you have to > throw more reaction mass during the early phases of the trip to > maintain constant acceleration. okay, I agree with the esthetics of yur argument, that is it makes sense that the same amount of energy will produce the same amount of acceleration regardless of it's use, but I would like to see a few calculations just to be sure. you've already calculated the amount of energy needed to accelerate the exhaust stream, now convert that energy to photons and calculate the amount of thrust gained by reflecting them. BTW, what kind of acceleration do you gain just by absorbing the photons, and not reflecting them? > > I do realize, however, that one way or another you're going to > have to carry reaction mass to _decelerate_, whether you throw it > out the back with the help of beamed power or not. It turns out > that even if you have the fabled photon rocket, getting to any > high fraction of c requires substantially more fuel than payload; > this fuel/payload ratio _squares_ if you intend to both > accelerate and decelerate under your own power. So a practical > design could very well involve using beamed power to accelerate > and stored reaction mass to declerate. > Actually, we can slow down and scoop up reaction mass needed for the final slow down. I posted a formula by which scoop size needed to get a 10m/s^2 deceleration can be figured. From popserver Tue May 16 19:46:03 GMT 1995 X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil] ["2715" "Tue" "16" "May" "1995" "08:20:07" "-0500" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" "" "55" "Re: relativistic acceleration stuff" "^From:" nil nil "5" nil "relativistic acceleration stuff" nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA12176; Tue, 16 May 95 06:20:29 PDT Received: by maroon.tc.umn.edu; Tue, 16 May 95 08:20:08 -0500 In-Reply-To: <199504300023.RAA23296@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 800653470.026 From: Kevin C Houston To: Steve VanDevender Subject: Re: relativistic acceleration stuff Date: Tue, 16 May 1995 08:20:07 -0500 (CDT) Steve, I was going through my old E-mail, when I re-read this one from you and I think I have some newer (to me anyway) thoughts on them. On Sat, 29 Apr 1995, Steve VanDevender wrote: > required is 3.701E16 joules; therefore you have to receive beamed > power of 3.701E16 W in order to maintain a rate of 0.011645 kg of > reaction mass accelerated to 0.9996 c every second. > > This is complicated further by redshifting; as you reach higher > and higher velocities the effective power from the beam > decreases. In order for the ship to maintain a consistent 10 > m/s^2 acceleration in its frame, the beamer has to continually > increase its power. > This can be kept to an order of two magnitude. Beamer stays constant. > If you really could maintain 1 g acceleration in the ship frame, > you run into an even worse problem with getting beamed power -- > during the first year of acceleration, you watch the beam > decrease in power to effectively 0! But at the same (well I was gonna say time but that would lead to confusion) in the same way, the rate of change of everything on the ship decreases. It's just like going into a kind of hibernation. Thus the beamer sends out an energy pulse of about 2 L.Y. long. The crew then use the first L.Y.'s worth of energy to approach c to four or five decimals. The ship then nearly "keeps pace" with it's energy supply, and uses hardly any at all. This is possible because with very long time parameters, very little energy is needed to effect change, so that the crew "feels" awake, the clocks and other (mechanical/electrical/ chemical/bio-chemical) systems behave normally within the frame of the ship itself. > If you continue the > acceleration using stored fuel on the ship, the beamer is > completely inaccessible to you -- your velocity approaches an > asymptote with slope c that intersects the origin at about t = 1 > yr. You are completely unable to receive anything from the other > side of that asymptote, or in other words power transmitted after > about the first year of beamer (Earth) time; it's very much like > a black hole event horizon opens up 1 lyr behind you. Of course, > in reality maintaining continuous acceleration indefinitely is > pretty much impossible, but you are going to have to expect that > you won't get much beamed power once you get very close to c. No, I won't get much beamed _energy_ , I'll have plenty of power tho' because each of my seconds becomes worth hundreds of beamer seconds. So when I absorb one seconds worth of energy, it suffices me for nearly two minutes beamer time because my demand for energy (in any form) has decreased. Kevin From popserver Wed May 17 19:29:24 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8094" "Wed" "17" "May" "1995" "08:39:28" "-0500" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "165" "Re: relativistic acceleration stuff" "^From:" nil nil "5" nil "relativistic acceleration stuff" nil nil] nil) Received: from maroon.tc.umn.edu by efn.efn.org (4.1/smail2.5/05-07-92) id AA01662; Wed, 17 May 95 06:39:41 PDT Received: by maroon.tc.umn.edu; Wed, 17 May 95 08:39:28 -0500 In-Reply-To: <199505162301.QAA13293@tzadkiel.efn.org> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-UIDL: 800738860.023 From: Kevin C Houston To: Steve VanDevender Subject: Re: relativistic acceleration stuff Date: Wed, 17 May 1995 08:39:28 -0500 (CDT) > Kevin C. Houston writes: > > > > > > This can be kept to an order of two magnitude. Beamer stays constant. > > What are you saying here? That the beam only has to vary in > magnitude by an "order of two", or that it stays constant? Both. The Beamer sends a constant wavelength. The ship only sees the wavelength vary by a factor of ~130 near midpoint. (velocity is limited to .99997 c due to the ship reducing acceleration before midpoint) > > To maintain constant acceleration _in the ship's rest frame_, the > ship must receive a constant amount of energy _in its frame_. As > the ship accelerates away from the beamer and reaches higher > velocities, _it will see the beamer output go down in energy_. > If you claim anything else, you haven't been studying your > relativity theory. You keep making the mistake (or the mis-type) of equating energy and power (power = energy/time) so that as time slows down, power goes up for an equal amount of energy or stays constant for a decreasing amount of energy. In order to maintain a constant acceleration, the ship must recieve a constant amount of _power_ in it's frame, and that can be affected by time dialation parameters. > > > If you really could maintain 1 g acceleration in the ship frame, > > > you run into an even worse problem with getting beamed power -- > > > during the first year of acceleration, you watch the beam > > > decrease in power to effectively 0! > > > > But at the same (well I was gonna say time but that would lead to > > confusion) in the same way, the rate of change of everything on the ship > > decreases. It's just like going into a kind of hibernation. Thus the > > beamer sends out an energy pulse of about 2 L.Y. long. > > The crew then use the first L.Y.'s worth of energy to approach c to four > > or five decimals. The ship then nearly "keeps pace" with it's energy > > supply, and uses hardly any at all. This is possible because with very > > long time parameters, very little energy is needed to effect change, so > > that the crew "feels" awake, the clocks and other (mechanical/electrical/ > > chemical/bio-chemical) systems behave normally within the frame of the > > ship itself. > > I don't think you understand what goes on. If the ship maintains > constant acceleration at 1G, it can only see about 1 year's worth > of power. IT NEVER SEES LIGHT EMITTED FROM THE BEAMER AFTER > THAT, UNTIL ITS ACCELERATION DECREASES. please don't shout. I understand full well what is going on here, I'm just having a little difficulting explaining what I mean to you. first point, I'n not talking about open-ended acceleration, I'm talking about the trip we are planning to T.C. the ship will be under acceleration for about 3/4 of a year. that is, they will only accelerate with power from the first 9 months of the beam. then they will turn around and begin decelerating. > > Draw a spacetime diagram with a hyperbola opening to the right > whose asymptotes are the lines t = x/c and t = -x/c. The > worldline of the uniformly accelerated ship corresponds to the > hyperbola. In this diagram, the ship starts at a nonzero x = 1/a > (a is the acceleration) at t = 0. Light is constrained to move > along worldlines of the form t = x/c + k and t = -x/c + k, for > any arbitrary constant k. What light lines can intersect the > hyperbola? At what times and locations can those light beams be > emitted in the global frame? Using the four regions bounded by > the asymptotes, you'll see that only light from the region below > t = x/c can ever reach the ship. Light from above that region > never reaches the ship. Similarly, the ship can only send light > to the region above t = -x/c. > Imagine yourself to be floating in space watching the trip from a long ways off. what would you see as a stationary observer. 1) Time=0 days Sol system begins beaming and "Asimov" begins accelerating. 2) Time~365 days. Ship reaches near light speed (time=c/a) dist ~.5 L.Y. 3) Time~547 days. Dist ~1 L.Y. Earth stops sending Beam. Ship and beam travel nearly as one, that is to say that the tail end of the beam does not move apreciably nearer to the ship. Time is very slow on ship by factor of ~130:1 4) dist=5.98 L.Y. ship begins decelerating. Tail end of beam begins to move toward ship again. 5) midpoint+547 days dist=11.9 L.Y. ship arrives at T.C. tail end of beam arrives at T.C. also > > No, I won't get much beamed _energy_ , I'll have plenty of power tho' > > because each of my seconds becomes worth hundreds of beamer seconds. So > > when I absorb one seconds worth of energy, it suffices me for > > nearly two minutes beamer time because my demand for energy (in any form) > > has decreased. > > No, you are mixing frames, and thereby ruining your argument. > Draw everything out in a frame that is inertial (the ship's frame > is accelerating, so it is invalid as an ongoing reference for > analysis in special relativity). When the beamer emits one > second of energy in your global frame, it takes much more time > than that along the ship's worldline for that second of energy to > be received when the ship is at high velocity. In the case of > sustained acceleration, only a finite amount of energy from the > beamer is ever visible to the ship; energy emitted after a time > 1/a (a is the acceleration in 1/m units) can never reach the > ship. I agree that we can't accelerate forever, and for the reason you state. However, by the time you had accelerated to that point, you're time rate would be so slow, that for all practical purposes you'd be standing still. (i.e. you could cover light-years of distance in a single "hour" of your awareness) the small amount of additional acceleration you might accomplish over these multi-light-years of space would feel like 10m/s^2 to you on the ship, but it wouldn't increase your energy or momentum very much (as measured by the outside observer) Ok, I'm traveling at .99997 c (no accel), and getting my power from a beam coming from behind. Power in the beam is 1000 KJ/s. The beam is at a wavelength of 130 cm as measured by the stationary beamer. So that the wavelength I "see" is 1 cm. (of course, I cooked the numbers). So the energy in the beam that I can use is 130 times less than if I were stationary or energy in one second of beam = 7.69 KJ. But my time rate is 130 times slower than the beamer's. so that I will recieve 130 seconds of beam (as measured by the beamer) in only 1 second (as measured by me) this is 7.69 *130 =1000 KJ. Time dialation conspires with lorentz contraction to provide me with the same amount of _power_. > > You really should sit down and read _Spacetime Physics_. You're > making elementary errors in reasoning about relativistic physics. > I have taken a modern physics course in college, although much of it was wave equations, we did have some relativity training. I will be reading "Spacetime Physics" and the gravitation book you mentioned over the summer. Since you have read these books recently, here's a project for you: come up with equations for the ship that: 1) show ships velocity as a function of ship time (St) assuming constant accel. ex. v=f(St,a) 2) show ship's distance from earth in earth-sized meters D as a function of ship time assuming constant accel. ex D (in meters)=f(St,a) 3) the amount of exhaust mass Em moving at .9996 c required to accelerate a ship at 10 m/s^2 (as felt by the crew) as a function of ship's total mass Mt. ex. Em=f(Mt,a) 4) the rest mass (as measured by the crew) of that exhaust. ex. Rm=f(Em,.9996c) 5) The power (in units of energy) needed on board to accelerate that mass flow to .9996c (assume stored energy on board to make it easier) ex. P=f(Rm,.9996c) This will enable us to track time and energy requirements of the "Asimov" much better than in the past. Hopefully I'll be able to dump these formulas into the spreadsheet, and model the trip much better. Kevin From popserver Sun Dec 31 18:13:11 GMT 1995 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1812" "Sun" "31" "December" "1995" "15:23:59" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "40" "Re: Engineering Newsletter" "^From:" nil nil "12" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id GAA05466 for ; Sun, 31 Dec 1995 06:22:50 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA03264 (5.67b/IDA-1.5 for ); Sun, 31 Dec 1995 15:23:54 +0100 Message-Id: <199512311423.AA03264@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, hous0042@maroon.tc.umn.edu, stevev@efn.org, rddesign@wolfenet.com, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com Subject: Re: Engineering Newsletter Date: Sun, 31 Dec 1995 15:23:59 +0100 >This page is _so cool_ that I've stayed up until 3:30 am looking >at it: > >http://www.fourmilab.ch/cship/cship.html Yes, I had found it a month ago or so, and downloaded it all, (took some time though) now I've a copy at my own HDD. I had in mind telling you about it, but when 2 weeks ago I walked around in your netpage, I saw that you already had a link to C-ship. I tried contacting the author, but have a hard time getting answers. He only replied my first email very shortly. The next letter involved some questions but I haven't heard from him since. >Although his starship design is simplistic and intended more for >expository purposes than as a completely realistic design, it >does have some interesting features I haven't seen us discuss >before. In particular he discusses the need for streamlining (!) >for a ship that travels at high relativistic speeds. In essence >it's a self-powered ship fueled by antimatter. He assumes that the interstellar medium and the background radiation give much drag, I think that is neglectable for speeds under .99c (and probably even higher) >The coolest part, though, is a couple of MPEGs that show trips >through his imaginary "lattice galaxy" at relativistic speeds. >This is exactly the kind of thing I want to do with my starship >simulation program (still completely embryonic at this point), >but with a database of real stars in the Solar neighborhood. >View the MPEGs, and then we can talk about why it looks like >you're flying backwards at the start of a trip. These 6 mpeg have a total size of 5 Mb, so for the other who are interested, be warned. The rest of the pages is about 1 Mb including the images. I myself have some doubts about some points in the simulation, but as I said before, the author doesn't answer my questions. Timothy From popserver Tue Jan 9 05:53:05 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6344" "Mon" "8" "January" "1996" "21:40:15" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "165" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id SAA23753 for ; Mon, 8 Jan 1996 18:40:14 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id VAA22883; Mon, 8 Jan 1996 21:40:15 -0500 Message-ID: <960108213807_86279596@emout06.mail.aol.com> From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl cc: stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, hedmarc@cellpro.cellpro.com Subject: Re: Engineering Newsletter Date: Mon, 8 Jan 1996 21:40:15 -0500 > > to: Rick > > > > > >>> Now, is there any thing at AC worth going there for? > > > >Is there anything in Tau C? You got a problem with multiple star systems or > >something? > > > >Kelly > > I have no problem with multi-star systems but will they support > planets that would be stable for life? And you are right, Is there > anything at TC worth going to either. Who knows? We have no idea what areas life can handel. If nothing else a very different starsystem could answer a lot of questions, especiall with three stars of different types. Of course we'ld know where the planets were before we sent of the mission. > The problems is were we live, and probably true for space as a whole, with > few stars "close" to us. The problem of living in a spur of a sprial arm, > kind of out of the mainstream. Like being in a town that the Intestate > jogged around. :-) Unfortunatly, this is an unusually empty area of space. Both in starsystems and in interstellar matter. > > To Timothy: > > >stage total weight (tons) thruster pack and stage structure > >1 1,000,000,000 10,000,000 > >2 40,000,000 400,000 > >3 2,000,000 70,000 ton ship > > with 5-10,000 tons of > > drive systems. > > > >This assumes a 100 to 1 thrust to weight ration for a fussion drive systems > >(which is questionable), and once you get where your going, coming back is > >out. But it would give us huge fuel ratios for relativistic flight. > > Possibly a multi stage fusion craft to get to the star and build a fuel > >launcher systems for two way flight? I'll have to think on this. > > I assumed that we could build a variable thrust engine, but for > weight-savings staging may be better. Yes, the weight of the huge engines we'ld need at the start would dominate the ship after a little while. > I think that staging would not solve a more fundamental problem: Pressure > One can see the engine as a force pressing on the back of the ship. We want > a certain acceleration a. The heavier the ship gets, the bigger the force > that is needed to get that acceleration (F=m*a). But assuming the backside > of the ship stays about the same, the pressure (p=F/Area) gets bigger and > bigger. --- Do you mean the thrust loads? If so we will need to take that into consideration. But we can use some of the fuel or reaction mass as structure (ice perhaps?) and the structure needed to carry the load shouldn't be a major fraction of the fuel mass. > > >> * LIT "ASIMOV" * > >> * Starship Design * > > > >You might have noticed I hate the name Asimov for the ship. It gives the > >whole project a grade school feel. I mean lets be real. This is a name that > >would never be acceptable to a real starship project. > > I never liked it much either, I guess the vote was done by passer-by-ers on > the Web. I can recal that I added the optimistic name 'New Eden' :) > What did you vote Kelly? I never even heard their was a vote until the 'winner' was announced. Thou I guess since I picked Explorer for my design, that would count as a vote. > >> * Manned: > >> * Without crew procreation > >> * Suicide (explore and die before your time when supplies end) > >> * One-way (outpost construction and stay till natural death) > > > >Suicide and one way are the same. We couldn't biuld a self sustaining > >outpost, and wouldn't fund resupply flights forever unless there was > >something in it for us (or a fantastic improvement in star drives back home). > > NO ONE would fund a one-way flight. > > I don't agree with you on that (yet?), I will expect an answer on > my letter of 01-05 10:55. What letter? The ones in my inbox don't have that time? Given that fantastic trouble NASA has always had justifing risking people in space. The idea of deliberatly sending them to their deaths is ludacrus! Every politician who ever came near you would rush to lead the witch hunt to fire you and anyone who ever asked you a question. Any public interest in the project would immediatly turn to revulsion at such a suggestion. The whole concept of interstallar flight would be off limits for years, even if someone else came up with a two way idea. > >> * Use the interstellar medium > > > >We have no real idea how to, or for that matter know whats out there to use. > > There is just too little, unless we can scoop an area with a 1000 km radius. Again we don't even know whats out their, but it does seem unlikly that it will be able to help us any. > >> * Power from installations at Solar system > > > >Beamed power or fuel launchers have the advantage of offloading the need to > >carry the heavy fuel (and power systems) with the ship. That improves the > >ships power to weight ration significantly. But the systems are difficult to > >do, limit range, and don't seem to help us to slow down. > > Also they have a not so good efficiency. (A big part of the beam just flies > along the ship without being used.) Thats true of beamed power, not launched fuel. > >> 3. Gravity on board > > > >I think the idea I came up with for a multi segmeny hab ring is the best. We > >need gravity for the crew, and the rotating hab segments will allow it to > >adapt to changing thrust directions. Unless the ship can operate under > >continuous thrust for the full flight. This seem best. > > You would always need the rotating rings, because in the time that you spend > at TC you don't have acceleration because of engine-thrust. True. I guess my had ring idea covers all requirement well enough to be assumed in a ship. > >> 4. Mission composition > > > >Given the size the main ship must be, I don't think we could afford 2. Which > >is a pity from a safty standpoint. A robotic pathfinder would be a good idea > >if it would work, but I'm dubious. > > > >A suply ship sounds a little risky. How would you like to be waiting in the > >target system for the next 5 years groceries. > > The idea of supply ships is to send them first and wait for them to arrive > savely, unfortunately that would take 20 years from their launch. No a good > way for food. 20 year old rations? Kelly From popserver Wed Jan 10 05:04:25 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2930" "Wed" "10" "January" "1996" "00:17:02" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "64" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id PAA03985 for ; Tue, 9 Jan 1996 15:16:04 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA03942 (5.67b/IDA-1.5 for ); Wed, 10 Jan 1996 00:16:55 +0100 Message-Id: <199601092316.AA03942@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Wed, 10 Jan 1996 00:17:02 +0100 Timothy replies to Kelly: >> I think that staging would not solve a more fundamental problem: Pressure >> One can see the engine as a force pressing on the back of the ship. We want >> a certain acceleration a. The heavier the ship gets, the bigger the force >> that is needed to get that acceleration (F=m*a). But assuming the backside >> of the ship stays about the same, the pressure (p=F/Area) gets bigger and >> bigger. --- > >Do you mean the thrust loads? If so we will need to take that into >consideration. But we can use some of the fuel or reaction mass as structure >(ice perhaps?) and the structure needed to carry the load shouldn't be a >major fraction of the fuel mass. I'm not sure of what you mean with thrust loads. What I meant was that the beams that connect the engine with the ship may not be able to stand the load. It's like you were pulling a very heavy cart with a sewing thread. For most metals the pull- or press-strength is about the same and in the magnitude of 4E8 N/m^2 You have a solid beam of iron (7.8E3 kg/m^3) with sizes 10x10x5000 metres. It would weigh 10*10*5000*7.8E3=3.9E9 kg Now you want to accelerate is with 9.8 m/s^2 you do that by equally excerting pressure at the 10x10 area. That would mean a pressure of (3.9E9*9.8)/(10*10)=3.8E8 N/m^2 As you can see the pressure is almost to is maximum and any unperfection will probably have caused it to snap earlier. I thought of a way to overcome this problem though, just add some (probably more than 10) extra engines. Then the load per engine could be less and so could the stresses. These extra engines should NOT be placed at the back (that would not change the problem) but along the side of it. >>I don't agree with you on that (yet?), I will expect an answer on >>my letter of 01-05 10:55. > >What letter? The ones in my inbox don't have that time? Maybe you have one of 6 hours earlier due to timezones, but I will send it to you again. >> >> * Power from installations at Solar system >> > >> >Beamed power or fuel launchers have the advantage of offloading the need >to >> >carry the heavy fuel (and power systems) with the ship. That improves the >> >ships power to weight ration significantly. But the systems are difficult >to >> >do, limit range, and don't seem to help us to slow down. >> >> Also they have a not so good efficiency. (A big part of the beam just flies >> along the ship without being used.) > >Thats true of beamed power, not launched fuel. The advantage of a lower ship:fuel ratio is that it needs less energy. If one decides to launch that fuel instead of adding it to the ship from the start, there is not much gain: Although the weight of launched fuel is less, there is a large extra amount of energy needed to launch that fuel. It follows from calculations that the total gain is not so big as you would have thought. But what you have added is a complicated launch method. Timothy From popserver Fri Jan 12 03:57:19 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["17239" "Thu" "11" "January" "1996" "21:30:51" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "382" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout06.mail.aol.com (emout06.mail.aol.com [198.81.10.43]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id SAA14790 for ; Thu, 11 Jan 1996 18:32:33 -0800 (PST) Received: by emout06.mail.aol.com (8.6.12/8.6.12) id VAA08095; Thu, 11 Jan 1996 21:30:51 -0500 Message-ID: <960111212801_88210828@emout06.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Thu, 11 Jan 1996 21:30:51 -0500 Zenon! I did get you letter but was going to try to shuffle the catagories around and see if I could come up with something. I will respond! Oh, I still say there is no significant difference between a suicide flight, and a flight where the crew are abandoned with enough supplies to last them their life. I am frankly shocked that you and Tim could seriously suggest such a horrific and ruthless option. Thats like sending a team to antartica, on a one way trip to the pole with no resuply and recovery runs! "Hey guys, go there, explore, radio back what you find, and here's 50 years supplies and parts for you to live out you life with." Timothy replies to Kelly: > > >> I think that staging would not solve a more fundamental problem: Pressure > >> One can see the engine as a force pressing on the back of the ship. We want > >> a certain acceleration a. The heavier the ship gets, the bigger the force > >> that is needed to get that acceleration (F=m*a). But assuming the backside > >> of the ship stays about the same, the pressure (p=F/Area) gets bigger and > >> bigger. --- > > > >Do you mean the thrust loads? If so we will need to take that into > >consideration. But we can use some of the fuel or reaction mass as structure > >(ice perhaps?) and the structure needed to carry the load shouldn't be a > >major fraction of the fuel mass. > > I'm not sure of what you mean with thrust loads. Thrust is the presure on the ship from the engines that shoves the craft along. > What I meant was that the beams that connect the engine with the ship may > not be able to stand the load. It's like you were pulling a very heavy cart > with a sewing thread. For most metals the pull- or press-strength is about > the same and in the magnitude of 4E8 N/m^2 > > You have a solid beam of iron (7.8E3 kg/m^3) with sizes 10x10x5000 metres. > It would weigh 10*10*5000*7.8E3=3.9E9 kg > Now you want to accelerate is with 9.8 m/s^2 you do that by equally > excerting pressure at the 10x10 area. > That would mean a pressure of (3.9E9*9.8)/(10*10)=3.8E8 N/m^2 > As you can see the pressure is almost to is maximum and any unperfection --- This really isnt a problem Tim. All large systems have to distribute their strructural loads amoung enough structure to get the job done. The shuttle tanks for example weight 30 tons, yet can carry about 750 tons of fuel at multiple G accelerations, and provide expensive structural bracing for the fources of the attached solid boosters and orbiter. Our starship design would be comparativly trivial. >-----These extra engines should NOT be placed at the back > (that would not change the problem) but along the side of it. Sorry they have to be at the back. Otherwise they would be blasting the sides of the ship. > >>I don't agree with you on that (yet?), I will expect an answer on > >>my letter of 01-05 10:55. > > > >What letter? The ones in my inbox don't have that time? I just got it, never saw it before thou. Responce below. > >> >> * Power from installations at Solar system > >> > > >> >Beamed power or fuel launchers have the advantage of offloading the need > >to > >> >carry the heavy fuel (and power systems) with the ship. That improves the > >> >ships power to weight ration significantly. But the systems are difficult > >to > >> >do, limit range, and don't seem to help us to slow down. > >> > >> Also they have a not so good efficiency. (A big part of the beam just flies > >> along the ship without being used.) > > > >Thats true of beamed power, not launched fuel. > > The advantage of a lower ship:fuel ratio is that it needs less energy. If > one decides to launch that fuel instead of adding it to the ship from the > start, there is not much gain: Although the weight of launched fuel is less, > there is a large extra amount of energy needed to launch that fuel. > It follows from calculations that the total gain is not so big as you would > have thought. But what you have added is a complicated launch method. You keep missing the point that the ship doesn't need to be generating the power to accellerate the fuel. Tus it would need as much fuel for power. The over all energy expenditure of the systems is irrelavant. ============================= the lost letter =========== > Timoty replies to Kelly: > > >Fusion is an extreamly usefull general purpose technology. Anti-matter is > >far less so, and far more dangerous on the scale we would need. I wouldn't > >expect a lot of anti-mater ships in 50 years. > > You shouldn't see anti-matter as a fuel, but more as efficient energy > storage. Why is anti-matter not a fuel? Because we have to make it. > Coparing these two is like comparing a petrol car with an electric car. The > energy for an electric car has to come from other fuels. Although the weight > advantage with electric cars may not be evident yet there are other > advantages. One of the advantages is the independancy of the origin of the > fuel source. If it is fusion, fission or solar energy all are easely > converted to electric energy which is relative easy to handle. > So what car-batteries are for us now, anti-matter will be for fast spacevessels. What electric cars are now, is exotic impractical and dangerous (and oddly not particularly clean). Fusion fuel can be mined and stored fairly easily. Anti-mater is a nightmare to hold in quantity, and in our case difficult to use efficently. Again certainly beyond the tech of 2050. > >Oh, that would be beyond the resources and tech of the project. Also it seem > >a waste of time. Sort of novelty project for the record books. With no > >practical reason to stay perminently there the bases would be prefab ghost > >towns. Future missions to other solar systems would have to be based out of > >dynamic, growing, large scale, civilizations. Not out of a staging camp in > >the middle of nowhere. > > If it really is to get a entry in the record books and not much more that > would really be a shame of all resources. If people really want to do that, > I see the end of humanity near. Would you say the same about missions to the Earths poles? Fairly common and trivially cheap compared to this. A far, far more habitable environment than any alien planet is likly to offer. Yet no one has attempted to colonize Antartica. What would be the point? > About growing civilizations, I don't think that western cultures will expand > that much. In the US the birthrate is 2.05 per female, in Europe it's about > 1.8. So that would mean that population will decrease. > The mean reason that Earth's population is still increasing are the less > developed countries which have birthrates of 4 to 7. > I think that families in developed countries have less children because of > the care these children need (financial but also social/tutorial). > So this means that we probably never need to go to other places. Well I wasn't refering to growing in population (and actually you have all thouse birth rates to high), but growing technically, economically, etc... Obviously games like these are only for the very rich. > But if we want to explore and discover new places we may want outposts at > many places. So building small colonies would not be that crazy then. > These colonies would have two purposes, the outpost and a research function. > There would probably many researchers that like to check a foreign planet. A base I could agree to, but not a colony. They are too isolated and to dependant on that long supply line from earth. Thou they are rich in resorces (ore and fuel). Without the infastructure and personel to exploit it, thats irrelavant. Without something big to attract major numbers of people here (which you seem to agree) they would stay to smal to be an independant population. At best they'ld be people rotated back to earth with the next supply run. I keep coming back to the isolation. It takes to long to get a ship out there and back, and costs too much to send it for this to be a colony or even a sustainable outpost. > >Forever? Do you expect earth to keep funding these people in this base > >forever? With continuous supply flights from sol to keep them going? We > >couldn't even keep the moon program going for more than a few months after it > >planted its flag. > > After some time they could have build a small colony with all facilities > needed to live and work. The energy they need comes from TC itself. So Earth > would need funding them, but since they have build a "nice" place in the > middle of an interesting place they may be interested to hear something of them. > You may argue that building a colony is difficult in an alien environment, > but by that time we will have some experience in building things on the Moon > or Mars. Moon and mars are also unsuitable (low gravity). More important you keep expecting them to live off the land. Thats like droping a hundred people in kansas with a small truck load of gear each, allow no trade with the out side, and expect them to build a ultra-modern city. Not likely. > >> Why don't you expect them to do that? I still don't see that as suicide, > >> they can live perfectly healthy lives. > > > >Thats like condeming somone to spend the rest of their lives in an > >apartment/shoping mall! Good researchers will want to retire or go on to > >other projects. Not sit around in a worn out ship, in the middle of nowhere, > >with nothing to do. > > Other projects, they have all the choice they could have. Who's going to > tell them that they cannot do what they want. The only limits are the ones > of themselves. Again you seem to be assuming they have tremendous resources of equipment and time. They would be extreamly limited, and given the dangerous nature of their mission. They are probably going to be losing stuff (people and equipment) fairly quickly. Without Earth benificent supply runs. They are going to be in bad shape fairly soon. > The people going there aren't the people who really want to retire, these > are people that are born for exploration and research. (They really exist) > My guess is that they wouldn't sit all the time in some ship or compartment, > but that they would allow themselves to go to the planets surface (in > spacesuits). Most of them will never be able to go to the planets. After a while none of them will be able to as the equipment runs out. If they have to plan on a long stay, they'll have to curtail exploration fairly quickly in order to save the equip for more practical uses. > >Sorry, no. In large projects like this the sum of the parts is the lowest > >common denominator of everyone. It becoming a big issue in the U.S. The > >more people you get on a project, the less energy and inovation is avalible. > > Things get bogged down, lost in committe misunderstanding, ecetera. Costs > >can go up to hundreds of times what a small tight group could do it for. > > And do you know why this happens, because everyone wants his own share and > no one is prepared to accept an idea of an other because that will mean a > loss of personal profit. No its more fundamental than that. Theirs just too many people. The more people the more corrdination efforts. For example I worked in the Space Station Freedom headquarters along with a few thousand other people. NONE of us actually worked on the space station. We worked to coordinate information between all the groups. The more people, the harder it is to keep everyone informed. On a big goverment project, everyone has to know what everyone else is doing. The more agencies, the more paths of interaction. Since governments tend to demand everything is monitored to the finest detail. The vast bulk (maybe 80%-90%) of the group effort is in meeting and reports to keep everyone else informed. > >Thats one of the reasons that over the last decade or two, NASA has been > >incapable of trying, or developing, cutting edge technologies or programs. > > Maybe even one country is too big? Certainly one buracracy is! > >> Exploration isn't much fun? What else drives people to such far places... > > > >Curiosity, greed, a chalenge, desire for fame or acomplishment. Exploration > >is generally horiobly uncomfortable and life threatening. But its very > >chalenging, and its atractive to know your one of the few to ever do > >something, know something, etc... Even if you know its killing you. > > Sorry, I had a more lossy idea about the word exploration than you did, I > meant approximately what you wrote. > > >Like an anthro professor my wife had. He loved studying aborigional tribes > >in the backwaters of the Amazon, but he frely admitted everyone who does it > >expect that they've paid with decades off their life expectancy. > > So that means a return trip won't be necessary. These people all wanted to come back. They wanted to go back out to the bush again, but not forever, and not to die. > >Since your dealing with radically differnt life forms. Its unlikely the old > >rules, or solutions, would hold. We mostly will be starting from scratch. > > After all, we have no experience with alien biospheres. > > I doubt if they are so radically different, all lifeforms have to abide the > laws of nature. Maybe some of them have found tricks that have not been > found on Earth but that is why we are going there. > And still if we know what doesn't work the chances of finding > something that does work are enlarged. Why not radically differnt? Life on earth is all based on a couple of basic chemical and anitomical tricks. There isn't anything special about those tricks. MANY others would work as well. I imagine most life out their will be radically different from that here, and may have a few times as long as Earth had to develop. > >We're in a serous bind. The tech we can expect in 50 years isn't enough for > >a T.C. flight. Or all but the most modest interstellar flights. NOr would > >they be that likely to be interested in footing a huge program. Yet if we > >back up the date by a hundred years we could be much more confident that they > >could do it, and do it affordably, but we wouldn't have any credible idea > >how! > > So maybe we should say "a priori" that certain techniques are > available. And discuss how and why these could be used. I suggested that a few months ago and got no interest. I suppose it moves this project from a serious attempt to figure out if we could do it in 2050. To a science fiction club. > >Put another way. Are we that likely to be so afraid of human extinction, > >that we'll rush to do such a project in 50 years? > > You can never tell :) people are worring about many things (like asteroids > colliding with Earth or the Asimov :)) > If humanity ever becomes extinct, it will be likely that it is not because > of natural disasters. Well nature is our worst enemy, but then we are very hard to kill. More to the point we could built fleets of O'Niel sized space colonies here for far less than this project. And they wouldn't have the resorce, access, and communication limits of a star colony. > >Oh certainly. The united states gets several million of them a year! But, > >another star doesn't offer much opportunity. It isolated, expensive, no > >markets to go to, few resorces that you can get at. No home world to go to > >on vacation to. Your very dependand on the supply line from Sol, and their > >for far less independant than you would be in a colony in Sol. > > You indeed can't go on vacation, and it probably never will have more than > 1000 inhabitants for the first 100 years. But as every place where people > live, they will adapt themselves and the environment. Not all people want to > become rich by selling stuff, a lot of them just want a place to life as > they like with the "sky" as the only limit. As I said before dependancy is > only a short time (if at all), once there is TC-light and gravity they can > grow food just as on Earth. So the first necessaries of life should not be > that difficult. I would say just the oposite. Life on a T.C. colony will be hard and very limited. The planets would be ignored, and the platform colony would need a lot of work to equip and maintain. They would be far more dependant and under the control of whoever runs the supply flights, then a similar colony in Sol space. > >Also, the kind of people we would send on such a ship. Would be the ellete > >that would have a lot of opportunity back home. The people who want a new > >start, wouldn't be sent on the ship. > > If you are 25 to 30 how sure can you be that you are a member of that elite. If you didn't already have the credientials,you wouldn't be offered a ride. (You would be stunned at the credentials NASA can require for astrounauts that only get to fly every yeear or three. On the other hand the turn over rate among the astronuate is pretty high. They are highly competative people. After they do this, they want new chalenges and get bored. > Also it doesn't have to be a new start but a first very defiant start. ?? Defiant of what? Defiannce doesn't work very well when you are dependant on others. From popserver Sat Jan 13 04:23:33 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["15236" "Sat" "13" "January" "1996" "01:42:17" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "293" "Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id QAA07547 for ; Fri, 12 Jan 1996 16:41:15 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA08539 (5.67b/IDA-1.5 for ); Sat, 13 Jan 1996 01:42:11 +0100 Message-Id: <199601130042.AA08539@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Engineering Newsletter Date: Sat, 13 Jan 1996 01:42:17 +0100 Timothy replies to Kelly: >Oh, I still say there is no significant difference between a suicide flight, >and a flight where the crew are abandoned with enough supplies to last them >their life. I am frankly shocked that you and Tim could seriously suggest >such a horrific and ruthless option. Thats like sending a team to antartica, >on a one way trip to the pole with no resuply and recovery runs! "Hey guys, >go there, explore, radio back what you find, and here's 50 years supplies and >parts for you to live out you life with." Summarizing what I write in this letter: - We have to discuss what is necessary for a small colony. - You can't compare Antarctica with a new planet full of life. - We (or I) don't see it as dropping people without any regard, but as a well organized lifetime adventure. - Do things break down or get lost faster than one can repair or replace them? >This really isnt a problem Tim. All large systems have to distribute their >strructural loads amoung enough structure to get the job done. The shuttle >tanks for example weight 30 tons, yet can carry about 750 tons of fuel at >multiple G accelerations, and provide expensive structural bracing for the >fources of the attached solid boosters and orbiter. Our starship design >would be comparativly trivial. For these shuttle tanks the bottoms have the highest pressure while the top has a low pressure. (It could be left open, at least for the matter of pressure). So the weight of the tanks isn't the main clue but the size of the bottom is (assuming that every part of the bottom gets the same pressure). So a tank with a large bottom and the same weight has much less pressure at that bottom. (The total force stays the same, the surface gets bigger). So it would be wise to build the walls of the tanks thick at the bottom and thinner at the top. Also the welds are more likely to break at the bottom than at the top. What I'm trying to say is thus that the bottom part is most vulnerable, For the pressure at the bottom of the shuttle tanks, I can estimate: (assuming a 3.5 metre diametre of the bottom) (750+30 tons)*3g/(10 m^2)=830*3000=2.34E6 Pascal That means it is still 170 times less than the maximum pressure (about 4E8 Pa) So a large and heavy spaceship could be build but the load-surface should be large enough. The load surface is in fact equal to the surface of the ends of the beams that are connected to the engine. So taking long beams makes no difference, only taking thick beams does. Now where I was going to, if the ship becomes very large and the engine surface too small there isn't enough support-surface and the thing can't work. I realize of course that it takes a big ship to make these problems real. But how big will the support-surface of the engine for the Asimov be? 300 square metres (and engine with a radius of 10 metres) would mean that the Asimov could weigh about 3E10 kg. >>-----These extra engines should NOT be placed at the back >> (that would not change the problem) but along the side of it. > >Sorry they have to be at the back. Otherwise they would be blasting the >sides of the ship. Maybe a cone shaped vessel with the largest radius in front (anti-streamlined) would work. How had you planned to connect the torus-shaped hab-rail to the ship? The loads of a 100 metre arm should be multiplied by 100! >You keep missing the point that the ship doesn't need to be generating the >power to accellerate the fuel. Tus it would need as much fuel for power. > The over all energy expenditure of the systems is irrelavant. It is indeed clear to me that the ship does need less power, because it doesn't need to accelerate its own fuel. But if the over all expenditure of the system is irrelevant, why is it such a problem to accelerate a 1:1000000 ship:fuel combination? Such a ship would accelerate, it just needs a lot of engines (or one very powerful one). By the way I still don't see how you possibly can say that the amount of energy needed doesn't matter. (Yes, I know as long as we have no working method...) ============================================================================ >What electric cars are now, is exotic impractical and dangerous (and oddly >not particularly clean). Fusion fuel can be mined and stored fairly easily. > Anti-mater is a nightmare to hold in quantity, and in our case difficult to >use efficently. Again certainly beyond the tech of 2050. Yes, but so is 1E18 Watt during a few years. (You would create the same energy in a day as the Sun would in a second) OK, enough about anti-matter, I hope I've made clear what the advantages are if we can use this techniques savely. I accept that 2050 will not be ready for anti-matter but I also have strong doubts if any technique can handle the high power we need. What I expect to happen in the futere is that anti-matter will find its way at the same time that such enormous power finds it way. >Would you say the same about missions to the Earths poles? Fairly common and >trivially cheap compared to this. A far, far more habitable environment than >any alien planet is likly to offer. Yet no one has attempted to colonize >Antartica. What would be the point? On the poles you won't find a whole new planet full of life. If we indeed knew there were only a few boring planets with nothing more than dust, we would probably go somewhere else or not go at all. >A base I could agree to, but not a colony. They are too isolated and to >dependant on that long supply line from earth. Thou they are rich in >resorces (ore and fuel). Without the infastructure and personel to exploit >it, thats irrelavant. Without something big to attract major numbers of >people here (which you seem to agree) they would stay to smal to be an >independant population. At best they'ld be people rotated back to earth with >the next supply run. How many people should there be for an independant colony? I think 100 people should make a living possible. You indeed cannot expect large factories, but these aren't necessary since there are not many people. >> You may argue that building a colony is difficult in an alien environment, >> but by that time we will have some experience in building things on the >> Moon or Mars. > >Moon and mars are also unsuitable (low gravity). Yes, but they will have build structures for people working there for a few months. >More important you keep >expecting them to live off the land. Thats like droping a hundred people in >kansas with a small truck load of gear each, allow no trade with the out >side, and expect them to build a ultra-modern city. I'm not sure I know what Kansas is like, but surely if they had some habitation-modules from the year 2050 they could prosper. The modules have a self sustained climate, their only input is energy (from a small anti-matter-tank :) or just plain old solar-panels). Not only its climate is self-sustained but also vegetables and other food would would be grown. So now that you have your first-aid life support for one or two persons in say 300 cubic metres, you want something to do. OK in Kansas you probably could do nothing at all, but on TC you might want to get out. So what you need more is a bunch of basic construction machines and ore-extracters. These indeed are the things that use the most room and weigh the most. But they also could be used by more than one person. Now I'm interested to know what would be the minimal amount of machines to start at a reasonable level. (say the level of our current technology, meaning pentium-computers, Scanning microscopes etc.) I've not a good idea of what to take, do you? (Has this subject been discussed before?) - Life sustaining habitats. - Nano tech would be a great help for ore extracters - Machines to make simple metal, plastic forms. A lot of these machines we probably need on the Asimov during its 25 year mission, most computer won't last for 25 years continuous work. Taking with us a lot of reserve chips seems a bit too simplistic to me. (Even the food growing-machines are nessecary, eating 10 year old food all the time is yuck) >Again you seem to be assuming they have tremendous resources of equipment and >time. They would be extreamly limited, and given the dangerous nature of >their mission. They are probably going to be losing stuff (people and >equipment) fairly quickly. Without Earth benificent supply runs. They are >going to be in bad shape fairly soon. How fast are they loosing too much supply in a two-way mission? Even such a mission should stay there for about 10 years researching planets. They will be loosing stuff but if it goes in the rate you are predicting, then every mission is suicide. >> The people going there aren't the people who really want to retire, these >> are people that are born for exploration and research. (They really exist) >> My guess is that they wouldn't sit all the time in some ship or >> compartment, >> but that they would allow themselves to go to the planets surface (in >> spacesuits). > >Most of them will never be able to go to the planets. After a while none of >them will be able to as the equipment runs out. If they have to plan on a >long stay, they'll have to curtail exploration fairly quickly in order to >save the equip for more practical uses. That may indeed be the case, but a 10 year exploration with 100 people is hardly enough to do any real research of a complete solarsystem. Not to mention refueling or building complete beaming-arrays (only advanced nano-tech or anti-matter might overcome that problem). >No its more fundamental than that. Theirs just too many people. The more >people the more corrdination efforts. For example I worked in the Space >Station Freedom headquarters along with a few thousand other people. NONE of >us actually worked on the space station. We worked to coordinate information >between all the groups. The more people, the harder it is to keep everyone >informed. On a big goverment project, everyone has to know what everyone >else is doing. The more agencies, the more paths of interaction. Since >governments tend to demand everything is monitored to the finest detail. The >vast bulk (maybe 80%-90%) of the group effort is in meeting and reports to >keep everyone else informed. What if everyone informed themselves? It's like the internet, people make information available, othera read it and if they don't agree, they discuss it with the author, after discussing they come to a common conclusion (if not, that's because of stubbornness) which is made public again. Also not all people need to know about everything in such a big project, there are many specialized groups, but they should not loose the survey of the project. >> Maybe even one country is too big? > >Certainly one buracracy is! Then there may be a big problem, because such a big project would need a lot of people. >These people all wanted to come back. They wanted to go back out to the bush >again, but not forever, and not to die. Going to the bush doesn't take 5 to 7 years plus 5+ years of preparation. I only wonder those people come back, do you know that? I can lively imagine that there are also people who want to stay simply because the find that special lifestyle so fascinating. >Why not radically differnt? Life on earth is all based on a couple of basic >chemical and anitomical tricks. There isn't anything special about those >tricks. MANY others would work as well. I imagine most life out their will >be radically different from that here, and may have a few times as long as >Earth had to develop. The main tricks are based on storing and retreiving energy in and from molecules, that energy comes from the sun or from planet-heat (vulcanos). Are there many easy reactions that can do that back and forth. (a cycle reaction is probably to unlikely) On Earth that reaction is H2O+CO2 <--> O2+CnHm by the use of sunlight. Then there are aerobic creatures, that rely on (I hope I'm right) Sulphur or phosphor oxides for energy, but that is a single way reaction, once the sulphuroxide is used it is not reused. Also this substance is not likely to be available in large quantities for several billion years. I'm not sure how many basic trick theres are, but I think it would be very likely that the alien creatures use oxigen and CnHm as main food. Assuming this basic trick, a lot of conditions are already set. And if the basic conditions are set, so are the creatures that spring from it. >I suggested that a few months ago and got no interest. I suppose it moves >this project from a serious attempt to figure out if we could do it in 2050. > To a science fiction club. Then we should end the discussion about engines with the conclusion that only exotic fuels and/or enormous powerstations could make the trip possible. The techniques needed are only in a early theoretical stage and the size of what is necessary is (almost) beyond imagination and reasonabless. >> You can never tell :) people are worring about many things (like asteroids >> colliding with Earth or the Asimov :)) >> If humanity ever becomes extinct, it will be likely that it is not because >> of natural disasters. > >Well nature is our worst enemy, but then we are very hard to kill. Even on a planet 10 ly away? >More to the point we could built fleets of O'Niel sized space colonies here >for far less than this project. And they wouldn't have the resorce, access, >and communication limits of a star colony. You say these colonies are dependant on Earth, what if such a disaster happens, then they won't have much resources any more. >I would say just the oposite. Life on a T.C. colony will be hard and very >limited. The planets would be ignored, and the platform colony would need a >lot of work to equip and maintain. They would be far more dependant and >under the control of whoever runs the supply flights, then a similar colony >in Sol space. At sol there can't be planet based colonies because of the wrong gravity. (only Venus has a comparable g but it's a bit hot out there) You keep saying that it takes a lot of effort to keep the colony working, I wonder if that is true: Do you need to repair a lot in your house? (not a personal question) OK, a house on a barren planet would be different, but I cannot believe that everyone is constantly busy repairing things. >If you didn't already have the credientials,you wouldn't be offered a ride. > (You would be stunned at the credentials NASA can require for astrounauts >that only get to fly every yeear or three. On the other hand the turn over >rate among the astronuate is pretty high. They are highly competative >people. After they do this, they want new chalenges and get bored. Probably the normal astronauts are suited for such a trip. If they indeed want new challanges every few years, they are probably on the wrong trip. This trip is a carreer for life, even if you make it a two-way trip. >> Also it doesn't have to be a new start but a first very defiant start. > >?? Defiant of what? Defiannce doesn't work very well when you are dependant >on others. I think I meant challenging, those damn dictionaries.. Timothy From popserver Sat Jan 13 04:23:43 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1324" "Fri" "12" "January" "1996" "19:57:30" "-0500" "David Levine" "David@interworld.com" nil "34" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: David@interworld.com Received: from www.interworld.com (interworld.com [165.254.130.4]) by caritas.efn.org (8.7.3/8.7.2) with ESMTP id QAA08679 for ; Fri, 12 Jan 1996 16:57:06 -0800 (PST) Received: from hal ([165.254.130.90]) by www.interworld.com (post.office MTA v1.9.1 ID# 0-11464) with SMTP id AAA47; Fri, 12 Jan 1996 20:01:27 -0500 Message-ID: <30F7037A.DFD@interworld.com> Organization: InterWorld, Really Cool Stuff Division X-Mailer: Mozilla 2.0b5 (WinNT; I) MIME-Version: 1.0 References: <199601130042.AA08539@student.utwente.nl> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: David@interworld.com (David Levine) To: Timothy van der Linden CC: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Fri, 12 Jan 1996 19:57:30 -0500 Just a quick note: Many people seem to be saying "What's the point of going there? We don't know for sure that there's anything interesting, and this is going to be hellishly expensive, if it's even possible." If this is going through anybody's mind, please remember that this is a thought experiment. We're trying to decide how we could go to the stars, if we wanted to. Yes, right now we probably don't want to. But assume we did. Assume that several planets have been detected at our target star, and spectral analysis even reveals the presence of chlorophyll, or some other definite indicator of the existance of life of some kind. Of course, if such a situation arose, we probably WOULD try to get something out there ASAP... but it would most likely be an unmanned probe. And while I think everyone agrees this would be a more sensible course of action, it's not as inherently interesting as a manned mission. And unmanned missions have been designed many times before. Manned missions have only been looked at sporadically. So let's assume that there is some reason to send people as well. I'll turn this "excuse" over to someone else... Anyway, remember: this is a thought experiment. Why we are going is not as important as HOW we are going - is it possible, and if so, how could it be done? -David From popserver Sat Jan 13 18:04:00 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1273" "Sat" "13" "January" "1996" "15:49:08" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "29" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id GAA08852 for ; Sat, 13 Jan 1996 06:47:58 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA14525 (5.67b/IDA-1.5 for ); Sat, 13 Jan 1996 15:49:00 +0100 Message-Id: <199601131449.AA14525@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Sat, 13 Jan 1996 15:49:08 +0100 Timothy replies to David: >And while I think everyone agrees this would be a more >sensible course of action, it's not as inherently >interesting as a manned mission. And unmanned >missions have been designed many times before. Manned >missions have only been looked at sporadically. An unmanned mission has two possibilities, a not very extended survey of TC using technology of today. Or a more extended survey using the benefits of complicated AI. But since we don't know how fast AI will develop, we cannot say a lot of senseful things about it. >Anyway, remember: this is a thought experiment. Why >we are going is not as important as HOW we are going - is >it possible, and if so, how could it be done? Yes I know that the how aspect is most important but the reasons for discussing the WHY-aspect were: - A one-way trip would be much easier than a two-way trip. - The purpose of the trip has influence on the kind of crew and the load, which in turn may have influence on the design of the ship. - At the moment we are a bit in an impasse as for propulsion methods. - We wanted to know where possible fundings could come from. - Personally I thought it was an interesting question. Certainly while some of us don't agree with each other at all. Timothy From popserver Sun Jan 14 03:17:22 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7815" "Sat" "13" "January" "1996" "19:51:11" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "149" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id RAA12586 for ; Sat, 13 Jan 1996 17:49:52 -0800 (PST) Received: by maroon.tc.umn.edu; Sat, 13 Jan 96 19:51:12 -0600 In-Reply-To: <199601130042.AA08539@student.utwente.nl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: Timothy van der Linden cc: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@InterWorld.com, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Sat, 13 Jan 1996 19:51:11 -0600 (CST) Kevin wishes to interrupt: > Timothy replies to Kelly: > > >Oh, I still say there is no significant difference between a suicide flight, > >and a flight where the crew are abandoned with enough supplies to last them > >their life. I am frankly shocked that you and Tim could seriously suggest > >such a horrific and ruthless option. Thats like sending a team to antartica, > >on a one way trip to the pole with no resuply and recovery runs! "Hey guys, > >go there, explore, radio back what you find, and here's 50 years supplies and > >parts for you to live out you life with." > > Summarizing what I write in this letter: > - We have to discuss what is necessary for a small colony. > - You can't compare Antarctica with a new planet full of life. > - We (or I) don't see it as dropping people without any regard, but as a well > organized lifetime adventure. > - Do things break down or get lost faster than one can repair or replace them? Okay, Okay, I think we've all heard enough of this argument. Neither of you is going to change the other's mind. If all we can do is figure out how to send a one-way mission, then I think we can assume that it will never be used until someone comes up with a valid reason to send so many people off on a no-return mission. What's a good reason? Why, one that would attract enough qualified (intelectually and psychologically) volunteers of course. I think we all agree that it would be a good _idea_ to have a return flight, The question, is whether it is possible or not. i think it is, A one-way mission would only be sent in the direst of planetary emergencies (sun going nova, hostile aliens etc.) > >What electric cars are now, is exotic impractical and dangerous (and oddly > >not particularly clean). Fusion fuel can be mined and stored fairly easily. > > Anti-mater is a nightmare to hold in quantity, and in our case difficult to > >use efficently. Again certainly beyond the tech of 2050. > > Yes, but so is 1E18 Watt during a few years. (You would create the same > energy in a day as the Sun would in a second) Impractical and expensive, yes, but there are no tech dificulties. you would not be "creating" the energy, but only re-directing a tiny fraction of the sun's output. I would say it thusly "you would be using 1/3600 of the suns total output for a period of 2 years" After that, the energy could be used right here in Sol System for any other project that was desired. > OK, enough about anti-matter, I hope I've made clear what the advantages are > if we can use this techniques savely. I accept that 2050 will not be ready > for anti-matter but I also have strong doubts if any technique can handle > the high power we need. What I expect to happen in the futere is that > anti-matter will find its way at the same time that such enormous power > finds it way. > As to anti-matter and large energy requirements -- I think it would be far more useful to figure out how we can send the most mass for the least energy. Tim, if you want to postulate anti-matter, go ahead. give some rough idea of how you intend to make it and store it, and then let us argue about when we might expect it. I for one, will postulate beamed energy, and once I have a workable system, I will go about estimating the size and manufacturing time of the requesite array. same with Kelly's design, come up with a viable method of stopping and tell us how long it would take to come up with the tech. (or lhow long it will take to pre-load the decell track) Then when we have several methods, we can rank them according to speed of travel, tech level, and other factors, to come up with a viable method. Tim, i have a question for you regarding anti-matter, how do you intend to direct the "exhaust"? as I see it, anti-hydrogen would combine with normal hydrogen (scooped?) and this would result in a burst of Gamma rays in _all_ directions. how will you harness the momentum of these photons? assuming you can make and store the anti-hydrogen, how many Kg of anti-matter would you need to get to the target star? do we carry the return trip fuel with us? or try to make it from the target? if we are going to make it, what percentage of energy can be turned into anti-matter? (and you can't assum 100% eff. either, or then I can assume 100% eff. solar arrays and microwave converters ;) ) and where does the energy come from if you intend to make it? (one idea for storage of anti-matter, start with anti-hydrogen,made from slamming high-speed protons into a stationary target, and use fusion to work your way up to anti-iron does anti-matter give energy when it fuses with anti matter? i think it must. when you have a quantity of anti-iron, magnetize it and your storage problems are solved. many of these technologies probably won't be avail until 2250 AD :( ) > > I'm not sure I know what Kansas is like, but surely if they had some > habitation-modules from the year 2050 they could prosper. > The modules have a self sustained climate, their only input is energy (from > a small anti-matter-tank :) or just plain old solar-panels). Not only its > climate is self-sustained but also vegetables and other food would would be > grown. So now that you have your first-aid life support for one or two > persons in say 300 cubic metres, you want something to do. OK in Kansas you > probably could do nothing at all, but on TC you might want to get out. So ^^^^^^^^^^^^^^^^^ I thought you said you didn't know what Kansas was like. ;) (for information, it is totally flat, totally farming, and totally boring) > That may indeed be the case, but a 10 year exploration with 100 people is > hardly enough to do any real research of a complete solarsystem. Not to > mention refueling or building complete beaming-arrays (only advanced > nano-tech or anti-matter might overcome that problem). > One of the implicit assumptions I'm going to use is that some form of self-replicating machinery is possible. not nano-tech, and not self-directed either. I'm assuming that a robot can be made that can make a copy of itself given: premade circuit board (pentium level motherboard with cameras and wireless modems) and ready made ores. that is, some other machine refines the ores and gives our robot "ingots" of aluminum or silicon or whatever else it needs. The robot needs to do the following autonomuos tasks: 1) shape metal into any shape (most NC millers can do this today) 2) make a 1 meter by 1 meter solar cell from a solid ingot of silicon and proper doping materials (they work in vacumn, so much bulky equipment won't be needed 3) scoop or mine ore and bring it to a central location 4) wind motors, connect wires and other tasks required to make a copy of itself (note, while theoretically, one robot could make a copy of itself, in pactice, many would be assigned the task of turning out more robots A Semi-autonomous computer would direct all the robots, while humans would be available for debugging, and initial set-up. an ore processing machine will be required as well as constant oversight by one or more crew. these would then be able to first, turn out many copies of themselves, and then secondly, they could begin turning out the hectares of solar panels needed for the maser transmitters. the same system would work in Sol, as would work in TC This would solve the problem of super-large collecting arrays, by allowing geometric growth of the machinery needed to manufacture it. Kevin who _makes_ glass beads, but doesn't brag about it in off topic groups ;) just kidding Ric. From popserver Sun Jan 14 18:57:04 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7606" "Sun" "14" "January" "1996" "19:53:55" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "151" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id KAA28129 for ; Sun, 14 Jan 1996 10:53:52 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA00771 (5.67b/IDA-1.5 for ); Sun, 14 Jan 1996 19:53:37 +0100 Message-Id: <199601141853.AA00771@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, David@InterWorld.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 19:53:55 +0100 Timothy replies to Kevin: >Okay, Okay, I think we've all heard enough of this argument. Neither of >you is going to change the other's mind. If all we can do is figure out >how to send a one-way mission, then I think we can assume that it will >never be used until someone comes up with a valid reason to send so many >people off on a no-return mission. What's a good reason? Why, one that >would attract enough qualified (intelectually and psychologically) >volunteers of course. I think we all agree that it would be a good >_idea_ to have a return flight, The question, is whether it is possible >or not. i think it is, A one-way mission would only be sent in the >direst of planetary emergencies (sun going nova, hostile aliens etc.) You shouldn't say that neither one is changing their mind. I'm certainly not argueing to enforce my ideas on those of Kelly, I'm trying to figure out why we do so fundamentally disagree. Now after a few letters, I think it is getting clearer were our differences are. If you don't like to read these discussions that's fine, but I sometimes have the idea that discussions are too easely stopped, so that in the end both (or more) members still disagree and that means that the whole discussion was done for nothing. >boost colony (ship/worlds) to other systems?> Probably not, the Sun would have grown too large before you could use its nova. I think the increase of the Sun's radiation will not be that significant. >Impractical and expensive, yes, but there are no tech dificulties. you >would not be "creating" the energy, but only re-directing a tiny fraction >of the sun's output. I would say it thusly "you would be using 1/3600 of >the suns total output for a period of 2 years" After that, the energy >could be used right here in Sol System for any other project that was >desired. I'm sorry, I'm not sure how I got to the numbers but what I wrote between braces is totally wrong, you would need about 1/(1E8) part of the Sun's total output. Meaning a solar panel with a 1000 kilometre radius near Earth. >As to anti-matter and large energy requirements -- I think it would be >far more useful to figure out how we can send the most mass for the least >energy. That would always be anti-matter or a beam that is very tight. >Tim, i have a question for you regarding anti-matter, how do you intend >to direct the "exhaust"? as I see it, anti-hydrogen would combine with >normal hydrogen (scooped?) and this would result in a burst of Gamma rays >in _all_ directions. how will you harness the momentum of these photons? >assuming you can make and store the anti-hydrogen, how many Kg of >anti-matter would you need to get to the target star? do we carry the >return trip fuel with us? or try to make it from the target? if we are >going to make it, what percentage of energy can be turned into >anti-matter? (and you can't assum 100% eff. either, or then I can assume >100% eff. solar arrays and microwave converters ;) ) and where does the >energy come from if you intend to make it? I haven't a complete oversight, but can tell you what I have in mind: 1. Matter is injected by matter, so that the photons collide with normal matter. This matter is heated and will escape at the place of the lowest pressure, the backside. This anti-matter engine needs more matter than antimatter. (I think in this case the comparison is big with chemical or fusion engines) 2. When an electron and anti-electron collide from almost rest, then 2 photons of 511 KeV (2400 nm) are formed, so this means that photons of resonable equally wavelength are created. So that would allow some kind of mirror to reflect them to the back. To be honest sometimes there are 3 or more photons formed with a total energy of 1022 KeV but all have different wavelengths. Now the problem is how to get only (anti)electrons and no protons or other bigger particles. I haven't an aswer to that, so for now this method will not work. You also ask how efficient it will be, that is hard for me to estimate, but like most engines it has to be efficient otherwise it will melt away. This seems like an easy way out, but I think it is true. So what it is important that the products of the antimatter reaction are all discarded and not absorbed in the engine. If the end-products are controlable this may not be too hard. >(one idea for storage of anti-matter, start with anti-hydrogen,made from >slamming high-speed protons into a stationary target, and use fusion to work >your way up to anti-iron does anti-matter give energy when it fuses >with anti matter? i think it must. when you have a quantity of anti-iron, >magnetize it and your storage problems are solved. many of these >technologies probably won't be avail until 2250 AD :( ) You could see anti-matter just as ordinary matter. All physic laws that are valid for matter do hold for anti-matter. Thus fusion would work. In fact Hydrogen is also a metal, it just has a very low melting point, I don't know however what its magnetic properties are. Also all materials have magnetic properties, though most don't have such a strong and autonomic fields as iron. So all materials will be attracted to or repelled from a magnetic field only some much more than others. >I thought you said you didn't know what Kansas was like. ;) >(for information, it is totally flat, totally farming, and totally boring) I had some feeling about what it should be like... >One of the implicit assumptions I'm going to use is that some form of >self-replicating machinery is possible. not nano-tech, and not >self-directed either. I'm assuming that a robot can be made that can >make a copy of itself given: premade circuit board (pentium level >motherboard with cameras and wireless modems) and ready made ores. that is, >some other machine refines the ores and gives our robot "ingots" of >aluminum or silicon or whatever else it needs. >The robot needs to do the following autonomuos tasks: I like the idea about such robots, especially because you could design them to build habitat units, or is that too difficult? >1) shape metal into any shape (most NC millers can do this today) What does NC mean? >2) make a 1 meter by 1 meter solar cell from a solid ingot of silicon and >proper doping materials (they work in vacumn, so much bulky equipment >won't be needed Even if needed (because of dust attracted and distributed by the ore-extracters) these vacuum pumps should not be that bulky. >these would then be able to first, turn out many copies of themselves, >and then secondly, they could begin turning out the hectares of solar >panels needed for the maser transmitters. the same system would work in >Sol, as would work in TC That would mean roughly 1E8 hectares, or about 3 hectares per second if you want to do it in 10 years :| The 1E7 masers would need to be build by robots too! This may need more complicate fabricating processes than solarcels. How much work can one robot unit do? Say 1m^2/second. So that means about 3E4 robots are needed. How long would one robot need to replicate itself? Say 3 days. Using exponetial growth: 2^T=3E4 --> T=173 --> 3*T=519 days needed to make 3E4 robots. If I use these numbers your plan could succeed. But are they realistic? 3 hectares per second seem so much. (You could really see it grow) Just a note: Would super conductors be any use to us? In free-space (not near a Sun) the temperatures are ideal for super conductors. Timothy From popserver Sun Jan 14 19:07:17 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1095" "Sun" "14" "January" "1996" "20:04:51" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "24" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id LAA28617 for ; Sun, 14 Jan 1996 11:03:27 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA01538 (5.67b/IDA-1.5 for ); Sun, 14 Jan 1996 20:04:42 +0100 Message-Id: <199601141904.AA01538@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, David@InterWorld.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 20:04:51 +0100 Timothy replies to David: >I'm sorry, Timothy - I didn't make myself clear enough. >All I meant was that it seemed like every now and then >people were thinking "Why, really, are we doing this >when we're not even sure of the reason for the trip... >We haven't even explored our own solar system yet..." >or any number of other lines of thought. I just didn't >want people too discouraged. Of COURSE it's an interesting >question, and I certainly realize the impact a one- or >two-way trip would have on the mission. I guess all I'm >really saying is that we should pick some reason for >going (even if it means deciding between several possibilities >at random), stick with it and say "How would we do the >trip assuming THIS is the reason we're going?" and not >worry too much about why that particular reason is the one >chosen. OK, I was never assuming we would not go, I see it more as a reality that we would go, I only have doubts about the date. (2050 seems to near) I haven't really noticed others thinking different from me. I'm wondering who gave you that idea... Greetings Tim From popserver Sun Jan 14 21:56:51 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9126" "Sun" "14" "January" "1996" "15:23:13" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "200" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: hous0042@maroon.tc.umn.edu Received: from maroon.tc.umn.edu (root@maroon.tc.umn.edu [128.101.118.21]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id NAA05387 for ; Sun, 14 Jan 1996 13:21:53 -0800 (PST) Received: by maroon.tc.umn.edu; Sun, 14 Jan 96 15:23:13 -0600 In-Reply-To: <199601141853.AA00771@student.utwente.nl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII From: Kevin C Houston To: Timothy van der Linden cc: KellySt@aol.com, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, rddesign@wolfenet.com, David@InterWorld.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 15:23:13 -0600 (CST) On Sun, 14 Jan 1996, Timothy van der Linden wrote: > Timothy replies to Kevin: > > >Okay, Okay, I think we've all heard enough of this argument. Neither of > >you is going to change the other's mind. If all we can do is figure out > > You shouldn't say that neither one is changing their mind. I'm certainly not > argueing to enforce my ideas on those of Kelly, I'm trying to figure out why > we do so fundamentally disagree. Now after a few letters, I think it is > getting clearer were our differences are. > If you don't like to read these discussions that's fine, but I sometimes > have the idea that discussions are too easely stopped, so that in the end > both (or more) members still disagree and that means that the whole > discussion was done for nothing. Oh, you two can go on argueing if you want to, don't let me stop you. I just thought that the ground had been covered many times before in finest detail. I did not realize that you were still confused as to what Kelly meant. i suppose that's my own fault for thinking that all members of this group speak english with perfect understanding (typical american attitude i know, but at least I can admit my mistake) I'm just glad this dicussion isn't taking place in Dutch or Polish > >Impractical and expensive, yes, but there are no tech dificulties. you > >would not be "creating" the energy, but only re-directing a tiny fraction > >of the sun's output. I would say it thusly "you would be using 1/3600 of > >the suns total output for a period of 2 years" After that, the energy > >could be used right here in Sol System for any other project that was > >desired. > > I'm sorry, I'm not sure how I got to the numbers but what I wrote between > braces is totally wrong, you would need about 1/(1E8) part of the Sun's > total output. > Meaning a solar panel with a 1000 kilometre radius near Earth. and a lot smaller if you could put in orbit at mercury's distance. > > >As to anti-matter and large energy requirements -- I think it would be > >far more useful to figure out how we can send the most mass for the least > >energy. > > That would always be anti-matter or a beam that is very tight. i don't agree, that's true only if you want to do it in a man's lifetime. if you are willing to accept a lower speed, then you can do the trip with a _lot_ less energy. > > >anti-matter would you need to get to the target star? do we carry the > >return trip fuel with us? or try to make it from the target? if we are > >going to make it, what percentage of energy can be turned into > >anti-matter? (and you can't assum 100% eff. either, or then I can assume > >100% eff. solar arrays and microwave converters ;) ) and where does the > >energy come from if you intend to make it? > > I haven't a complete oversight, but can tell you what I have in mind: > > 1. Matter is injected by matter, so that the photons collide with normal > matter. This matter is heated and will escape at the place of the lowest > pressure, the backside. This anti-matter engine needs more matter than > antimatter. > (I think in this case the comparison is big with chemical or fusion engines) > > 2. When an electron and anti-electron collide from almost rest, then 2 > photons of 511 KeV (2400 nm) are formed, so this means that photons of > resonable equally wavelength are created. So that would allow some kind of > mirror to reflect them to the back. To be honest sometimes there are 3 or > more photons formed with a total energy of 1022 KeV but all have different > wavelengths. > Now the problem is how to get only (anti)electrons and no protons or other > bigger particles. I haven't an aswer to that, so for now this method will > not work. > > You also ask how efficient it will be, that is hard for me to estimate, but > like most engines it has to be efficient otherwise it will melt away. This > seems like an easy way out, but I think it is true. So what it is important > that the products of the antimatter reaction are all discarded and not > absorbed in the engine. If the end-products are controlable this may not be > too hard. I meant by eff. Question, "what will the eff. of energy to antimatter conversion be?" or How many kilowatts does it take to make a gram of anti-matter? > > >(one idea for storage of anti-matter, start with anti-hydrogen,made from > >slamming high-speed protons into a stationary target, and use fusion to work > >your way up to anti-iron does anti-matter give energy when it fuses > >with anti matter? i think it must. when you have a quantity of anti-iron, > >magnetize it and your storage problems are solved. many of these > >technologies probably won't be avail until 2250 AD :( ) > > You could see anti-matter just as ordinary matter. All physic laws that are > valid for matter do hold for anti-matter. Thus fusion would work. > In fact Hydrogen is also a metal, it just has a very low melting point, I only if you put it under a hellish pressure. > don't know however what its magnetic properties are. > Also all materials have magnetic properties, though most don't have such a > strong and autonomic fields as iron. So all materials will be attracted to > or repelled from a magnetic field only some much more than others. > Actually, if we could get any respectable solid at all, like Li maybe, then we could give it an electricall charge and keep it suspended that way > >One of the implicit assumptions I'm going to use is that some form of > >self-replicating machinery is possible. not nano-tech, and not > >self-directed either. I'm assuming that a robot can be made that can > >make a copy of itself given: premade circuit board (pentium level > >motherboard with cameras and wireless modems) and ready made ores. that is, > >some other machine refines the ores and gives our robot "ingots" of > >aluminum or silicon or whatever else it needs. > >The robot needs to do the following autonomuos tasks: > > I like the idea about such robots, especially because you could design them > to build habitat units, or is that too difficult? no, I think that would be possible. > > >1) shape metal into any shape (most NC millers can do this today) > > What does NC mean? > Numerically Controlled, old fashioned term for computer controlled > >2) make a 1 meter by 1 meter solar cell from a solid ingot of silicon and > >proper doping materials (they work in vacumn, so much bulky equipment > >won't be needed > > Even if needed (because of dust attracted and distributed by the > ore-extracters) these vacuum pumps should not be that bulky. > > >these would then be able to first, turn out many copies of themselves, > >and then secondly, they could begin turning out the hectares of solar > >panels needed for the maser transmitters. the same system would work in > >Sol, as would work in TC > > That would mean roughly 1E8 hectares, or about 3 hectares per second if you > want to do it in 10 years :| > The 1E7 masers would need to be build by robots too! This may need more > complicate fabricating processes than solarcels. > > How much work can one robot unit do? Say 1m^2/second. > So that means about 3E4 robots are needed. > How long would one robot need to replicate itself? Say 3 days. > Using exponetial growth: 2^T=3E4 --> T=173 --> 3*T=519 days needed to make > 3E4 robots. Tim, i think you have a little problem here. 2^173= 1.19 E+52 robots =8^O In fact, I'm having trouble following where some of your numbers come from. assuming that your 1000 Km radius solar array is correct, I get (1000 * 1000)^2 *PI() = 3.14 E+12 m^2 of solar cells i think your estimate of solar cell production is way too liberal, I say 1 m^2/day is more likely. so now we need 8.6 E08 robots to do the job in ten years I think your three day replication estimate is good. using exponential growth, I get 2^T=8.6 E08 T=29 days 3 * T =89 days thats if we start with one robot. I think we would probably start with a 1000. if we let reproduction continue for 100 days ( nice round number) we'd have 8.59 E09 robots, and at the lesuirely rate of 1 m^2/day, we could build the entire solar array in 365 days. 100 robots could work on each maser transmitter, and all of them could be built in a month. we'd still have plenty of robots left over to build habitats, mine fusion fuel, or whatever other job we needed done. with that many pentium level processers, the resultant computer power would be staggering! Now, as Kelly says, when you get this many "Grunts", the job of the top boss becomes more and more difficult. but with several layers of "middle managment" computers, I think it would be doable ( although, maybe not at the speed I was reffering to > Just a note: Would super conductors be any use to us? In free-space (not > near a Sun) the temperatures are ideal for super conductors. yeah, I think we are going to need that technology in many areas. Computer circuitry, accelerator coils, fusion containment coils anywhere you have a lot of energy, and no way to remove the heat. Kevin From popserver Mon Jan 15 03:24:18 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2731" "Sun" "14" "January" "1996" "22:07:33" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "60" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail04.mail.aol.com (mail04.mail.aol.com [152.163.172.53]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id TAA21351 for ; Sun, 14 Jan 1996 19:09:49 -0800 (PST) Received: by mail04.mail.aol.com (8.6.12/8.6.12) id WAA29530; Sun, 14 Jan 1996 22:07:33 -0500 Message-ID: <960114220732_116630037@mail04.mail.aol.com> From: KellySt@aol.com To: hous0042@maroon.tc.umn.edu, T.L.G.vanderLinden@student.utwente.nl cc: stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 22:07:33 -0500 > Kevin wishes to interrupt: > > > Timothy replies to Kelly: ---- > --- same with Kelly's > design, come up with a viable method of stopping and tell us how long it > would take to come up with the tech. (or lhow long it will take to > pre-load the decell track) Then when we have several methods, > we can rank them according to speed of travel, tech level, and other > factors, to come up with a viable method. Of the two ideas I came up with (launched fuel and stages fusion rocket) they both are stuck with using stored on-board fuel for deceleration. No solid numbers yet but it looks like 20% to MAYBE 30% is doable. In more detail: For a fuel laucher based systems the ship takes off with a ful load of decel fuel and accelerates up the accelleration track wich is pre loaded with fuel. Its maximum speed is limited by how far they launcher can accuratly launch the fuel. I.E. how far from the launcher does the fuel become so dispersed that the ship can't scoop up enough for its needs. Anyway. The ship leaves sol with its decel fuel. Coasts to a star thats close enough (T.C. would not be close enough, so I'm assuming Alpha C or something else in the 4-6 ly range), then Decelerates with the onboard fuel. For the return flight, it can eiather accelerate with stored fuel and decel into sol using a Sol fuel launcher provided decel track. Or they could, maybe, biuld a fuel launcher atthe target system. This would allow that ship, and subsequent ships, to make the flight at speeds not limited by on-board fuel limitations. Possibly at much higher speeds. A multi stage ship is theoretically limited by how many stages you can get. But I think the specific impulse of the system will give an upper practical limit. Returning could be harder since you won't have all the stages. Tim I think the central difference between us is your expectation of being able to colonise a world and self sustain a colony or base with only a couple hundred people. Currently a self sustained society needs millions of people to keep going and cities full of hardware. I might be willing to accept that we might be able to do it with tens or hundreds of thousands of people in 50 years; but not hundreds, and certainly not with what a ship could carry. So given my expectation that planets with a bio-sphere would be unsurvivable for any period of time, and the crews will be strongly limited by the spare parts the ship can carry. The mision couldn't sustain the open ended operations you seem to be assuming. So going there doesn't give the crew the option of living on their own, or starting a sustainable society. This probably accounts for our different reaction toward one-way missions. Kelly From popserver Mon Jan 15 03:24:20 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["338" "Sun" "14" "January" "1996" "22:07:38" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "10" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from mail06.mail.aol.com (mail06.mail.aol.com [152.163.172.108]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id TAA21390 for ; Sun, 14 Jan 1996 19:11:10 -0800 (PST) Received: by mail06.mail.aol.com (8.6.12/8.6.12) id WAA20818; Sun, 14 Jan 1996 22:07:38 -0500 Message-ID: <960114220720_116629868@mail06.mail.aol.com> From: KellySt@aol.com To: David@interworld.com, T.L.G.vanderLinden@student.utwente.nl cc: stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 22:07:38 -0500 >> ---- Anyway, remember: this is a thought experiment. Why >> we are going is not as important as HOW we are going - is >> it possible, and if so, how could it be done? Well thats a good point. Of course the why effects the how. But since we don't seem to be geting very far in the how departments its probably a mute point. Kelly From popserver Mon Jan 15 05:05:53 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["13626" "Sun" "14" "January" "1996" "23:57:34" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "307" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: KellySt@aol.com Received: from emout05.mail.aol.com (emout05.mail.aol.com [198.81.10.37]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id UAA26569 for ; Sun, 14 Jan 1996 20:58:30 -0800 (PST) Received: by emout05.mail.aol.com (8.6.12/8.6.12) id XAA17237; Sun, 14 Jan 1996 23:57:34 -0500 Message-ID: <960114235734_42026576@emout05.mail.aol.com> From: KellySt@aol.com To: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, David@interworld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com Subject: Re: Engineering Newsletter Date: Sun, 14 Jan 1996 23:57:34 -0500 Kely Re:Timothy replies to Kelly: > > >Oh, I still say there is no significant difference between a suicide flight, > >and a flight where the crew are abandoned with enough supplies to last them > >their life. I am frankly shocked that you and Tim could seriously suggest > >such a horrific and ruthless option. Thats like sending a team to antartica, > >on a one way trip to the pole with no resuply and recovery runs! "Hey guys, > >go there, explore, radio back what you find, and here's 50 years supplies and > >parts for you to live out you life with." > > Summarizing what I write in this letter: > - We have to discuss what is necessary for a small colony. If it is to be self sufficent. It would need the resources of a small country now. (Thou no current country is self suficent, the current estimate is about 7 million people to maintain current society.) > - You can't compare Antarctica with a new planet full of life. True, Antartica would be far more habtable and survivable, but its the best quick example I could come up with. Then again, since antartic is so much easyier to settle, and we don't. Why would we settle in another star system. > - We (or I) don't see it as dropping people without any regard, but as a well > organized lifetime adventure. When the gear runs out. It will be far less adventurous, and much more tedious. > - Do things break down or get lost faster than one can repair or replace them? In aircraft, one lists how many man-hours of work per hour of flight. For exploration gear it could get that bad. I'ld expect the hab deck could keep going for a couple decades with minimal repairs. Probably the same for the heavy power and water systems. The mini ships and shuttles, or ground rovers would probably be geting tired after a few years of hard use. > How had you planned to connect the torus-shaped hab-rail to the ship? The > loads of a 100 metre arm should be multiplied by 100! See my Web page. In general the hab-deck track is attached to the outer hull. > >You keep missing the point that the ship doesn't need to be generating the > >power to accellerate the fuel. Tus it would need as much fuel for power. > > The over all energy expenditure of the systems is irrelavant. > > It is indeed clear to me that the ship does need less power, because it > doesn't need to accelerate its own fuel. But if the over all expenditure of > the system is irrelevant, why is it such a problem to accelerate a 1:1000000 > ship:fuel combination? Such a ship would accelerate, it just needs a lot of > engines (or one very powerful one). That asumes the engines can provide the thrust equivelent to 1,000,000 times their own weight. No engines now made can do that. The best fusion engines I've heard specilated about can do 6 times there weight. We could probably expect that to go up to 20, but not a million. > By the way I still don't see how you possibly can say that the amount of > energy needed doesn't matter. (Yes, I know as long as we have no working > method...) If it doesn't need to be carried by the ship, it doesn't effect the ability of the ship to function. That gear can stay at home and be serviced by facilities and people thatthe ship doesn't need to carry. ============================================================================ > >Would you say the same about missions to the Earths poles? Fairly common and > >trivially cheap compared to this. A far, far more habitable environment than > >any alien planet is likly to offer. Yet no one has attempted to colonize > >Antartica. What would be the point? > > On the poles you won't find a whole new planet full of life. If we indeed > knew there were only a few boring planets with nothing more than dust, we > would probably go somewhere else or not go at all. Doesn't matter for survival. Planets with Bio-spheres would be uninhabitable. Actualy its unlikely any planet would be habitable to us. > ------ Now I'm > interested to know what would be the minimal amount of machines to start at > a reasonable level. (say the level of our current technology, meaning > pentium-computers, Scanning microscopes etc.) > I've not a good idea of what to take, do you? (Has this subject been > discussed before?) Several times. > - Life sustaining habitats. > - Nano tech would be a great help for ore extracters > - Machines to make simple metal, plastic forms. > > A lot of these machines we probably need on the Asimov during its 25 year > mission, most computer won't last for 25 years continuous work. Taking with > us a lot of reserve chips seems a bit too simplistic to me. > (Even the food growing-machines are nessecary, eating 10 year old food all > the time is yuck) The heavy equip probably can give a 40 year service life. Computers can do a couple decades if well made, and are light enough so several sets of spares can be carried. To keep down the weight I was figuring no food rasiing on the ship. Instead 20 years of standard frozen foods in cryo, and 20 years of concentrated rations. The rations are only for use for the ship to hold on for rescue if they can't make it back. (I was assuming a standard mission of 20 years round trip. Thou we may need to streach it a bit more.) > >Again you seem to be assuming they have tremendous resources of equipment and > >time. They would be extreamly limited, and given the dangerous nature of > >their mission. They are probably going to be losing stuff (people and > >equipment) fairly quickly. Without Earth benificent supply runs. They are > >going to be in bad shape fairly soon. > > How fast are they loosing too much supply in a two-way mission? Even such a > mission should stay there for about 10 years researching planets. > They will be loosing stuff but if it goes in the rate you are predicting, > then every mission is suicide. Again I was expecting shorter missions, with a 2 maybe 3 year layover in system. > >> The people going there aren't the people who really want to retire, these > >> are people that are born for exploration and research. (They really exist) > >> My guess is that they wouldn't sit all the time in some ship or > >> compartment, > >> but that they would allow themselves to go to the planets surface (in > >> spacesuits). > > > >Most of them will never be able to go to the planets. After a while none of > >them will be able to as the equipment runs out. If they have to plan on a > >long stay, they'll have to curtail exploration fairly quickly in order to > >save the equip for more practical uses. > > That may indeed be the case, but a 10 year exploration with 100 people is > hardly enough to do any real research of a complete solarsystem. Not to > mention refueling or building complete beaming-arrays (only advanced > nano-tech or anti-matter might overcome that problem). Which was one of the reasons why I was arguing against such things. > >No its more fundamental than that. Theirs just too many people. The more > >people the more corrdination efforts. For example I worked in the Space > >Station Freedom headquarters along with a few thousand other people. NONE of > >us actually worked on the space station. We worked to coordinate information > >between all the groups. The more people, the harder it is to keep everyone > >informed. On a big goverment project, everyone has to know what everyone > >else is doing. The more agencies, the more paths of interaction. Since > >governments tend to demand everything is monitored to the finest detail. The > >vast bulk (maybe 80%-90%) of the group effort is in meeting and reports to > >keep everyone else informed. > > What if everyone informed themselves? It's like the internet, people make > information available, othera read it and if they don't agree, they discuss > it with the author, after discussing they come to a common conclusion (if > not, that's because of stubbornness) which is made public again. > Also not all people need to know about everything in such a big project, > there are many specialized groups, but they should not loose the survey of > the project. Doesn't really help. Instead of everyone getting to gether in a meeting where everyone presents their material and discuses it. You have people doing the same thing one at a time over the net. > >> Maybe even one country is too big? > > > >Certainly one buracracy is! > > Then there may be a big problem, because such a big project would need a lot > of people. If the project is organized by a small central group running autonomous projects. Its possible. Add in multiple governments and you have a big problem. > >Why not radically differnt? Life on earth is all based on a couple of basic > >chemical and anitomical tricks. There isn't anything special about those > >tricks. MANY others would work as well. I imagine most life out their will > >be radically different from that here, and may have a few times as long as > >Earth had to develop. > > The main tricks are based on storing and retreiving energy in and from > molecules, that energy comes from the sun or from planet-heat (vulcanos). > Are there many easy reactions that can do that back and forth. (a cycle > reaction is probably to unlikely)----- Lifes a lot more complicated then that. But if it all has the same chemistry it can counter attack. But the subtel chemistry and biostructures that immune defenses use could be completely wrong to deal with the threat. > >I suggested that a few months ago and got no interest. I suppose it moves > >this project from a serious attempt to figure out if we could do it in 2050. > > To a science fiction club. > > Then we should end the discussion about engines with the conclusion that > only exotic fuels and/or enormous powerstations could make the trip > possible. The techniques needed are only in a early theoretical stage and > the size of what is necessary is (almost) beyond imagination and reasonabless. Then what else is there left to talk about? > >> You can never tell :) people are worring about many things (like asteroids > >> colliding with Earth or the Asimov :)) > >> If humanity ever becomes extinct, it will be likely that it is not because > >> of natural disasters. > > > >Well nature is our worst enemy, but then we are very hard to kill. > > Even on a planet 10 ly away? I'm assuming we're not stupid enough to go on the planets. > > >More to the point we could built fleets of O'Niel sized space colonies here > >for far less than this project. And they wouldn't have the resorce, access, > >and communication limits of a star colony. > > You say these colonies are dependant on Earth, what if such a disaster > happens, then they won't have much resources any more. The colonies in Sol space can develop rapidly and become very large. Because they could pay for their own way they could afford that, and pay for all the supplies and equipment they'ld need. Should Earth be trashed somehow. They would at least have all their resources and the resources of the other colonies to draw on. What they need they could trade the recovering Earth civilization for. (Or salvage from the remains.) Unlike a couple hundred people in another star system. Who just have to hope the folks back home stay rich enough to pay for the supply flights. > >I would say just the oposite. Life on a T.C. colony will be hard and very > >limited. The planets would be ignored, and the platform colony would need a > >lot of work to equip and maintain. They would be far more dependant and > >under the control of whoever runs the supply flights, then a similar colony > >in Sol space. > > At sol there can't be planet based colonies because of the wrong gravity. > (only Venus has a comparable g but it's a bit hot out there) > You keep saying that it takes a lot of effort to keep the colony working, I > wonder if that is true: Do you need to repair a lot in your house? (not a > personal question) OK, a house on a barren planet would be different, but I > cannot believe that everyone is constantly busy repairing things. Again you can't use the planets. Of course people are constantly busy repairing or replacing everything! What do you think most of the efforts of civilization go toward here? We're constantly working to maintain and replace everything from homes and cars, to worn out cloths and paper clips. Except here we have a trmendous industrial advantage due to the scale of those operations. On a colony world it would be harder, and take longer. We'ld be forced to try to keep old equipment runing that really should be replaced. > >If you didn't already have the credientials,you wouldn't be offered a ride. > > (You would be stunned at the credentials NASA can require for astrounauts > >that only get to fly every yeear or three. On the other hand the turn over > >rate among the astronuate is pretty high. They are highly competative > >people. After they do this, they want new chalenges and get bored. > > Probably the normal astronauts are suited for such a trip. If they indeed > want new challanges every few years, they are probably on the wrong trip. > This trip is a carreer for life, even if you make it a two-way trip. > Who would volenteer for a trip that could take deacdes but only give them a couple years work in the star system? Or even worse if after that you are abandoned in the starsystems with nothing to do but last out as long as the ship holds out? Or worse yet, expected to slave away maintaing the thing, like being traped in a decades long Apollo 13 mission. Kelly From popserver Mon Jan 15 18:00:58 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1571" "Mon" "15" "January" "1996" "13:51:04" "+0100" "Zenon Kulpa" "zkulpa@lksu.ippt.gov.pl" nil "34" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: zkulpa@lksu.ippt.gov.pl Received: from sunic.sunet.se (sunic.sunet.se [192.36.125.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id EAA12394 for ; Mon, 15 Jan 1996 04:48:16 -0800 (PST) Received: from lksu.ippt.gov.pl by sunic.sunet.se (8.6.8/2.03) id NAA16954; Mon, 15 Jan 1996 13:49:38 +0100 Received: from zmit1.ippt.gov.pl by lksu.ippt.gov.pl (4.1/SMI-4.1) id AA17876; Mon, 15 Jan 96 13:51:04 +0100 Organization: Institute of Fundamental Technological Research Address: Swietokrzyska 21, 00-049 Warszawa, POLAND Message-Id: <9601151251.AA17876@lksu.ippt.gov.pl> From: zkulpa@lksu.ippt.gov.pl (Zenon Kulpa) To: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, KellySt@aol.com Cc: zkulpa@sunet.se Subject: Re: Engineering Newsletter Date: Mon, 15 Jan 96 13:51:04 +0100 > From KellySt@aol.com Fri Jan 12 03:34:37 1996 > > Oh, I still say there is no significant difference between a suicide flight, > and a flight where the crew are abandoned with enough supplies to last them > their life. I am frankly shocked that you and Tim could seriously suggest > such a horrific and ruthless option. Thats like sending a team to antartica, > on a one way trip to the pole with no resuply and recovery runs! "Hey guys, > go there, explore, radio back what you find, and here's 50 years supplies and > parts for you to live out you life with." > Horrific and ruthless? If you send them for such a trip against their will - then you are possibly right. But if they are willing? There is a good ol' rule of Roman law: "Who is willing, does not suffer" [sorry if I do not used the correct English version of the text]. Besides, everybody must die some time - what is that real & shocking difference between dying in Antarctica and in Sometown, Montana? With the starflight, another important factor is added: the return flight is long (of the order of at least 10 years, say), thus those returning will have only few years to enjoy their medals on Earth, not to say of the boring years on the ship with nothing exciting to do (except betting if the next ship gear failure will be fatal...) and rather risky - the probability of irreparable failure of the ship during the flight is much larger than the failure of the outpost base. I, frankly, would prefer to stay at the outpost. It might significantly increase my life expectance... -- Zenon From popserver Mon Jan 15 18:01:00 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1359" "Mon" "15" "January" "1996" "14:02:24" "+0100" "Zenon Kulpa" "zkulpa@lksu.ippt.gov.pl" nil "29" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: zkulpa@lksu.ippt.gov.pl Received: from sunic.sunet.se (sunic.sunet.se [192.36.125.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id EAA12670 for ; Mon, 15 Jan 1996 04:59:42 -0800 (PST) Received: from lksu.ippt.gov.pl by sunic.sunet.se (8.6.8/2.03) id OAA18694; Mon, 15 Jan 1996 14:00:58 +0100 Received: from zmit1.ippt.gov.pl by lksu.ippt.gov.pl (4.1/SMI-4.1) id AA17950; Mon, 15 Jan 96 14:02:24 +0100 Organization: Institute of Fundamental Technological Research Address: Swietokrzyska 21, 00-049 Warszawa, POLAND Message-Id: <9601151302.AA17950@lksu.ippt.gov.pl> From: zkulpa@lksu.ippt.gov.pl (Zenon Kulpa) To: T.L.G.vanderLinden@student.utwente.nl, stevev@efn.org, RUSSESS@cellpro.cellpro.com, jim@bogie2.bio.purdue.edu, David@interworld.com, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, KellySt@aol.com Cc: zkulpa@sunet.se Subject: Re: Engineering Newsletter Date: Mon, 15 Jan 96 14:02:24 +0100 > From KellySt@aol.com Fri Jan 12 03:34:37 1996 > > [...] > No its more fundamental than that. Theirs just too many people. The more > people the more corrdination efforts. For example I worked in the Space > Station Freedom headquarters along with a few thousand other people. NONE of > us actually worked on the space station. We worked to coordinate information > between all the groups. The more people, the harder it is to keep everyone > informed. On a big goverment project, everyone has to know what everyone > else is doing. The more agencies, the more paths of interaction. Since > governments tend to demand everything is monitored to the finest detail. The > vast bulk (maybe 80%-90%) of the group effort is in meeting and reports to > keep everyone else informed. > The key phrase is: "Since governments tend to demand everything [, everything] is monitored to the finest detail", not the "just too many people". 80%-90% of this "coordination" is not necessary. Did all people involved really READ (with attention) ALL that "coordination" stuff? Put the task as a question of survival (of the humanity, of the company, of the people involved...) instead of as a government project that must be reported back in all, important or not, details - and the effectiveness rises several times (if not orders of magnitude...). -- Zenon From popserver Tue Jan 16 18:04:57 GMT 1996 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["8996" "Tue" "16" "January" "1996" "17:59:09" "+0100" "Timothy van der Linden" "T.L.G.vanderLinden@student.utwente.nl" nil "179" "Re: Engineering Newsletter" "^From:" nil nil "1" nil "Engineering Newsletter" nil nil] nil) Return-Path: T.L.G.vanderLinden@student.utwente.nl Received: from student.utwente.nl (driene.student.utwente.nl [130.89.220.2]) by caritas.efn.org (8.7.3/8.7.2) with SMTP id IAA19862 for ; Tue, 16 Jan 1996 08:58:25 -0800 (PST) Received: from slp10048.slip.utwente.nl by student.utwente.nl with SMTP id AA11176 (5.67b/IDA-1.5 for ); Tue, 16 Jan 1996 17:59:03 +0100 Message-Id: <199601161659.AA11176@student.utwente.nl> X-Sender: S9421793@mail.student.utwente.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden) To: KellySt@aol.com, stevev@efn.org, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, David@InterWorld.com Subject: Re: Engineering Newsletter Date: Tue, 16 Jan 1996 17:59:09 +0100 Timothy replies to Kelly: >I think the central difference between us is your expectation of being able >to colonise a world and self sustain a colony or base with only a couple >hundred people. Indeed, that seems to be the difference between us, Zenon has a bit other attitude, saying that people should decide for themselves what they want (to which I do not agree completely but also do not disagree completely, it's like smoking, it's bad but not bad enough (No... I don't smoke)). Where Zenon and I do agree is that staying at TC may be less dangerous than flying all the way back home. >Currently a self sustained society needs millions of people to keep going and >cities full of hardware. I might be willing to accept that we might be able >to do it with tens or hundreds of thousands of people in 50 years; but not >hundreds, and certainly not with what a ship could carry. I've doubts about that, a lot of things are unnessary renewed also a lot of effort is used to develop new things, if we would maintain the current level of technology and not innovate, we probably had a lot more spare time. ============================================================================ >> - You can't compare Antarctica with a new planet full of life. > >True, Antartica would be far more habtable and survivable, but its the best >quick example I could come up with. Then again, since antartic is so much >easyier to settle, and we don't. Why would we settle in another star system. What I meant is that a new planet would give us more than Antarctica could, I don't mean that it could be a place to live, but a place to get much new scientific information. >That asumes the engines can provide the thrust equivelent to 1,000,000 times >their own weight. No engines now made can do that. The best fusion engines >I've heard specilated about can do 6 times there weight. We could probably >expect that to go up to 20, but not a million. OK, take 1 engine that could acclerate itself and 19 other engines, than the other 19 engines didn't need to accelerate themselves anymore so they could use all their power to accelerate the ship. >If it doesn't need to be carried by the ship, it doesn't effect the ability >of the ship to function. That gear can stay at home and be serviced by >facilities and people thatthe ship doesn't need to carry. Storing fuel doesn't need much that much facilities. >Doesn't matter for survival. Planets with Bio-spheres would be >uninhabitable. Actualy its unlikely any planet would be habitable to us. We would not live on those planets, we would do research in spacesuits or with remote controlled robots. Maybe after we had figured out an anti-dote against most diseases we might want to live there. I don't see why good planets without live could not be used. Slowly I'm thinking of not going to a planet to live there: The main advantage of a planet are its ore resources, (assuming you can't live there without spacesuits. So why would we want live on a planet at all, space-stations could live near asteroids for their ores, the could fly away whenever they had enough materials. This does not mean that going to a planet to research it isn't useful! >To keep down the weight I was figuring no food rasiing on the ship. Instead >20 years of standard frozen foods in cryo, and 20 years of concentrated >rations. The rations are only for use for the ship to hold on for rescue if >they can't make it back. (I was assuming a standard mission of 20 years >round trip. Thou we may need to streach it a bit more.) Aaagh 20 years of drinking porrige, OK I'm out, I won't go anymore. Although we could bake some bread or won't flour hold for that long? Nah, bread and porrige that still isn't eatable. >Again I was expecting shorter missions, with a 2 maybe 3 year layover in >system. That makes Kevin's array-building even more difficult. Also doing any real research would not be possible. Besides that 3 years research for 15 years of travel is not acceptable, it would really be a waste of man power. So I think your idea of the goal of the mission isn't right. >>>Most of them will never be able to go to the planets. After a while none of >>>them will be able to as the equipment runs out. If they have to plan on a >>>long stay, they'll have to curtail exploration fairly quickly in order to >>>save the equip for more practical uses. >> >> That may indeed be the case, but a 10 year exploration with 100 people is >> hardly enough to do any real research of a complete solarsystem. Not to >> mention refueling or building complete beaming-arrays (only advanced >> nano-tech or anti-matter might overcome that problem). > >Which was one of the reasons why I was arguing against such things. Huh, I can't follow you, am I right that you are against refueling or building beaming arrays? If so, than the trip may indeed become very difficult. >> The main tricks are based on storing and retreiving energy in and from >> molecules, that energy comes from the sun or from planet-heat (vulcanos). >> Are there many easy reactions that can do that back and forth. (a cycle >> reaction is probably to unlikely)----- > >Lifes a lot more complicated then that. Yes, but once you have the same base things are a lot less different. >But if it all has the same chemistry >it can counter attack. But the subtel chemistry and biostructures that >immune defenses use could be completely wrong to deal with the threat. Yes, we have also very powerful medcines, take penicillin, it has a very broad range, and can kill many diseases at once, probably a lot of extraterrestial ones too. >> Then we should end the discussion about engines with the conclusion that >> only exotic fuels and/or enormous powerstations could make the trip >> possible. The techniques needed are only in a early theoretical stage and >> the size of what is necessary is (almost) beyond imagination and >reasonabless. > >Then what else is there left to talk about? I don't know, maybe there are other interesting subjects where everyone like to discuss about. Or we should summarize and break up but that sounds so hard after 1.5 years of writing. >> Even on a planet 10 ly away? > >I'm assuming we're not stupid enough to go on the planets. Oh yes, I forgot that :)) >> At sol there can't be planet based colonies because of the wrong gravity. >> (only Venus has a comparable g but it's a bit hot out there) >> You keep saying that it takes a lot of effort to keep the colony working, I >> wonder if that is true: Do you need to repair a lot in your house? (not a >> personal question) OK, a house on a barren planet would be different, but I >> cannot believe that everyone is constantly busy repairing things. > >Again you can't use the planets. Why not even a lifeless ones assuming they have almost the right gravitation? >Of course people are constantly busy repairing or replacing everything! What >do you think most of the efforts of civilization go toward here? We're >constantly working to maintain and replace everything from homes and cars, to >worn out cloths and paper clips. Except here we have a trmendous industrial >advantage due to the scale of those operations. On a colony world it would >be harder, and take longer. We'ld be forced to try to keep old equipment >runing that really should be replaced. A lot of things in the current civilization are too easely discarded of, a lot of things are bought new because a single part needed to repair the thing is more expensive or not possible to buy. Besides that a lot of appliances aren't build to repair. I can give you dozens of examples where an easy single repair can save a whole apparatus but you have to do it yourself because others can't or won't repair it. Also a lot of the current resources are use for devellopment not for reproduction. On TC we don't need to worry how we can make faster computers or better lightbulbs for the first few decades. So this is why I think that a lot less people are needed than you suggest. The things that really need to be renewed are a lot less and so you need a lot less people. >> Probably the normal astronauts are suited for such a t