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Re: Re: starship-design: One way (again...)
In a message dated 12/11/97 6:55:35 AM, firstname.lastname@example.org wrote:
>> From: Kelly St <KellySt@aol.com>
>> In a message dated 12/8/97 3:24:52 PM, you wrote:
>> >From: Kelly St <KellySt@aol.com>
>> >> Then don't go by train. Most of our systems could get their once and
>> >> back easier and cheaper then going their and seting up infastructure.
>> >That is debatable.
>> >My opinion is that it would be cheaper to go one-way to establish
>> >infrastructure (as I have written before the biggest problem as for now
>> >is the propulsion - certainly going one-way halves this problem).
>> I disagree strongly. A construction expidition or a long duration mission
>> would need to be far better equiped, and far larger. Hence, both would be
>> more expensive.
>Due to the distances, the time duration of the two types of mission,
>when taking into account Isaac's calculations
>that most probably due to technologially affordable mass ratios,
>the cruise speed for the two-way mission would have to be halved:
This statment makes no sence to me, and none of the designs I've come up with
have shown this effect. We've all been talking about refuling the ship at the
target system. So the mass ratio for a one way or two way is the same. (Also
both my designs (explorer and Fuel/Sail) hav .33c and .42c cruse speeds, and
most every one else was pushing for faster ships.)
If you are for some reason assuming a 2 way trip without refueling, I'm not
sure mearly halving the cruse speed would allow you to stay withing the same
total fuel mass ratio.
> flight there (10 yrs);
> + sustained stay for the rest of the crew (natural) life
> (with life expectancy in space of 70 yrs, age at start 30yrs,
> and flight time 10 yrs, this phase will last 30yrs at most);
> = 40 yrs;
> flight there (20 yrs);
> + sustained stay for the exploration phase (5 yrs);
> + flight back (20 yrs);
> = 45 yrs.
>may actually be in favor of the one-way mission.
>Not speaking about the fact that those who return from
>the two-way mission will land on Earth five years
>after their life expectancy...
Only because your assuming a fairly short life expectance. With the high risk
environment of a mission like that, that might be justifiable, but for planing
purposes you'ld have to assume longer.
>Hence, the two-way mission will need approximately the same
>amount (and duration needs) of the equipment.
>But two-way will be much more demanding from the fuel/engine
>point of view (as Isaac correctly remarked, not simply two times
>more, but possibly orders of magnitude more).
This makes no sence. If your assuming the same total fuel ration on the ship
for a one or two way mission. You need the same total thrust from the engines
(but of course on the return leg you can stand dropout with less mission
impact). So how could the demands on the engines be orders of magnitude more,
or realisticly even twice as much? At most the engines firing time is twice
as much, but thats separated by years to do check out and servicing.
>Hence, which would cost more - still REMAINS DEBATABLE.
>Note also that in order to not became a suicide mission,
>the two-way mission plan must ALSO be capable to safely change it
>into one-way at target when the return flight becomes impossible
>for some quite probable reasons (engine failure, problems
>with fuel mining at target, etc.).
That would be desirable, but increasing the service life by more then 50%
would probably require MAJOR scale up in the ship systems and crew, which
would probably be untenable. Contingencies for those problems that allow a
return would need to be factored in, or a possible rescue mission (i.e.
diverting the next ship that could have been planed to be launched to another
>> >Especially in long run: two-way leaves practically nothing
>> >over there to go back for; establishing an outpost - well,
>> >establishes a target to return to (at least to help with new
>> >supplies them struggling over there...).
>> >Remember Apollo - a plant-the-flag mission has little consequences
>> >and does not lead to sustained exploration.
>> >The Russian "Mir", being a true outpost in near-space
>> >is since many years the only long-term space project -
>> >one of its main effects being prevention of Russian space program
>> >from a total collapse...
>> >The two-way mission "just to show it is possible" will also make
>> >a much less impact and consequence than the outpost-building.
>> No, we would not go somewhere just to go to an outpost. In itself,
>> an outpost isn't a goal or a reason for going somewhere.
>> At best its a tool to allow you to do something there.
>> At worst its a stunt. (Been there, done that, took
>> our bows, and went home.)
>Ahh, but the above applies even stronger to the two-way mission
>(especially the "and went home" part ;-)).
I don't follow that statement. It sounds like your saying if we have no
reason to go somewhere (or go back to) then stay there perminently?
>Hence, from this point of view one-way and two-way seem equivalent...
>> If your assuming a maned outpost, it would be a strong incentive to cancel
>> the first mission. I.E. to prevent being forced to eather:
>> send a retriaval expidition to bring them back, or to take the heat
>> for leaving them to die for some Apollo like stunt.
>You again with that "leaving them to die" rhetoric...
>And "leaving them to die" back on Earth is so much better?
Yes, obviously, for reasons I've stated several times, including above.
>Or "leaving them to die" during the long and quite boring
>return flight (of old age/sickness or in a catastrophic accident,
>much more probable during the return flight due to engine wear)?
The return flight would certainly be no more boring then being parked in the
target system. Eaither way you still stuck in the ship with no where to go.
But at least your going back somewhere at the end.
>> >And, Kelly, you seem to contradict yourself at the costs issue -
>> >in another post you have written:
>> >> From: Kelly St <KellySt@aol.com>
>> >> Date: Sun, 7 Dec 1997 10:59:57 EST
>> >> [...]
>> >> Thats effectivly a suicide mission. I know a few folks in this group
>> >> disagree, or don't care, but it still would meen no government on earth
>> >> could get permision for such a mission.
>> >> I.E. your throwing away a crew for no critical reason.
>> >> Specifically your doing it to save money,
>> >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> >> which is really not going to sell.
>> >I.e., you assume (and use it as an argument!)
>> >that one-way will save money... Voila!
>> I thought you had used that as an argument!? Why else would you not
>> equip an expidition with a return capability? I thought your whole
>> suggestion for this started as a suggestion to save money?
>You suggested that one-way will be much more costly (due to much
>larger needs for long duration supplies, repair factories, etc.).
>I had only countered your opinion on that, arguing that
>the costs might actually be smaller for one-way.
>My main arguments in favor for one-way were (and are):
>- technological feasibility;
>Cost is for me a secondary factor here, but, in my opinion,
>ALSO in favor of one-way.
>> >> >> Seariously a big question we've never gotten very far with is why
>> >> >> anyone would send such a mission?
>> >> >
>> >> >See, above. I still haven't found a sound reason to send any mission.
>> >> >Lee
>> >> Me neiather.
>> >> Kelly
>> >Yes, in short term, there isn't any.
>> >But remember Sagan:
>> >"All civilizations become either spacefaring or extinct."
>> Tese missions would in no way make us a more 'spacefaring civilization'.
>> They would however require us to already be a very space faring
>> civilization to launch them.
>Yes, before undertaking an insterstellar mission we must be
>already a very spacefaring civilization - in fact I have repeated
>this several times in our discussions in the past (and in the next
>paragraph of my previous letter too, see below).
>However, going interstellar will be the logical and ncessary
>NEXT step to become really spacefaring, not merely in-system-faring...
>We all agree that interstellar travel is orders of magnitude
>harder than in-system, hence being able to launch a starship
>will certainly signify that we are much more spacefaring
But, within the technical limits of the designs were coming up with. There
are no practical benifits, and some significal costs) to launching such a
mission. So launching it can't be considered important for the survival of
the civilization, in the sence of the quoted comment. I.E. It does not offer
the potential to increse resorces andmaerial, or ranges, accessable to human
>> >Of course, we must first settle our system to a significant
>> >degree (at least to be able to built a HUGE starship
>> >without hauling all that mass from Earth's gravity well).
>> >Thus, barring some great breakthrough like FTL,
>> >I do not see any real possibility (if not technological,
>> >then psycho-/econo-/political) to send a manned interstellar
>> >mission within 50 years or so.
>On the abvoe we agree, I presume? ;-0
Probably true. Certainly the costs would make this an unsustainable
enterprize with the systems we've come up with.
>> >Returning to Sagan, his prediction already seems to turn
>> >the dangerous way - as Kyle has remarked:
>> >> From: "Kyle R. Mcallister" <email@example.com>
>> >> The visionaries of our world are nearly gone. What I mean by this is
>> >> the ones that saw true worth in our exploration and expansion,
>> >> those such as Carl Sagan, Isaac Asimov, and the like are all dying.
>> >> The sad thing is, there seem to be few if any new visionaries
>> >> like them. I, being a teenager, spend considerable
>> >> time with other teenagers, and can tell you that the vision is gone.
>> >> Arthur C. Clarke and Rober Bussard won't be around forever.
>> >> I just wonder where the human in humanity has gone.
>> >Without opening a real big frontier in space, the humanity will
>> >decline even faster and earlier than we may expect.
>> >The symptoms are already quite visible.
>> I'm not sure what your talking about as symptoms,
>One example - a prominent member of the interstellar travel
>discussion list so strongly opposed to even considering
>one-way missions as a discussion option! ;-(
Because they have significant increased costs political, social, and economic,
and have no corresponding advantage. (and their is the moral issue involved.)
>> but their are plenty of
>> other visionaries. Many working to build more realistic and grand visions.
>> But they aren't as interesting to the public at the moment.
>You just pointed out another symptom...
Agreed, but that comes and goes in cycles. The public now isn't as interetsed
in mega projects. But that that changes.
>> Personally I think interest in space will perk up when space does do
>> At the moments its effects have been quite underwelming given the levels of
>> effort. A more productive space program, should gain more interest and
>Possibly, let us hope so.
>But without a vision and exploration spirit in plenty,
>there will be NO "more productive space program",
>or even any space program.
Not really. Most of the growth in space systems and programs, especially up
to the scale needed for a project like this, would have to come from
commercial interests, not from exploration, political, or scientific
interests. Such interests are making serious moves toward space, but have to
dismantal governmently roadblocks and sanctions. I'm not sure if you'ld
consider that "...a vision and exploration spirit in plenty.."?