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Re: starship-design: One way (again...)

L. Parker wrote:
>On Tuesday, December 09, 1997 9:55 AM, Isaac Kuo [SMTP:kuo@bit.csc.lsu.edu] 

>> Resources on a planet are much more plentiful than in space, and
>> much easier to get at (for the inhabitants).  Furthermore, building
>> habitats on a planet is much simpler than in space, because you get
>> radiation and space debris shielding for free.

>Yes, planets have more total resources perhaps, but typically they are not 
>as concentrated, and definitely harder to get at.

That really depends on what resources you're talking about.  I'm talking
about the surface and atmosphere resources--which are all we've been
able to sample so far anyway.

The thing about building habitats on asteroids is that you're still
limited to whatever resources happen to be on the asteroids and you've
got to import the rest.  That means you've got to spend the premium
of getting all your stuff by space ship.  And what do you have to
export?  Asteroid resources--until they run out.  These are all much
less of a problem on a planetbound colony.

>Current concepts for 
>orbital mining and manufacturing use the tailings to build shielding which 
>is more than adequate for any conceivable circumstance short of a nova.

Yes, but it still costs more than building habitats on a planet.

>As far as easy of construction, I will grant that we have very little 
>experience with this right now, but fifty years from now it either won't be 
>an issue or we won't be going, period. Or were you planning on building the 
>ship on the ground?

Huh?  We aren't talking about any interstellar mission in this subthread.
This is the question of orbital vs. planetary colonies.  I'm arguing that
there are indeed good reasons why you'd want to put a colony on a planet.

>> IMO, this mission is still too ambitious for a first manned mission.
>> A first manned mission cannot expect to get _any_ resources from the
>> target system, because that first system will be the planetless Alpha
>> Centauri system.

>Perhaps it is ambitious, but I think it is really the most likely way of 
>doing a successful program. BTW, where did you by your telescope? I want 
>one too. I didn't know there weren't ANY planets around Alpha Centauri.

Okay, it's theoretically possible for their to be exploitable planets
around Alpha Centauri.  I still don't think we'd be able to count on
even knowing about their existence, much less bring equipment to
exploit them, before a manned mission.  An unmanned radar probe could
find relatively large planets, but there's no reason to believe there
are even small planets there yet.

OTOH, we have good reason to believe a binary star system is much less
likely to have planets around them (because there are so much fewer
places to have a stable orbit).

>> I don't think an unmanned flyby probe would be able to find usable
>> resources even if they were there to be found (because it would
>> lack the human creativity to recognize and scientificaly interpret
>> something unexpected).  With the 8 year two-way time delays, I
>> don't think an unmanned 1-way probe would work out either.

>Probably true.

>> If there are resources to be exploited, then a 1-way manned mission
>> is the way to find it.

>> I think that we can send them there with the hope that they'll find
>> something they can turn into something useful, but trying to build
>> power stations from the hydrogen and helium of Alpha Centauran
>> solar winds is trying to squeeze water out of graphite.

>If we establish that there are no planets there, then obviously we wouldn't 
>attempt this kind of mission. Then again, we probably wouldn't send ANY 

IMO, we could and would eventually send a manned mission to Alpha
Centauri.  It's a beautiful scientific mission which actually does
have long term critical benefits to humanity in that it will provide
invaluble information about other star systems should we ever even
begin to think about interstellar colonization.

"What does it do to help our nation's defense?"

"It make our nation more worth defending."
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
/___________\ "Mari-san...  Yokatta...
\=\)-----(/=/  ...Yokatta go-buji de..." - Karigari Hiroshi