Re: Mini SD-newsletter

[T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)]

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

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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