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Subject: 
Re: We're here to go
Newsgroups: 
lugnet.off-topic.geek
Date: 
Fri, 16 Jan 2004 22:00:13 GMT
Viewed: 
733 times
  
In lugnet.off-topic.geek, Larry Pieniazek wrote:
In lugnet.off-topic.geek, Dave Schuler wrote:
By now, everyone knows about Dubya's Brave New Vision of America's future in
space, specifically regarding the Moon and Mars.  One of Dubya's selling points
for a permanent Moon base (perhaps modular, in 48x48 squares) is that it will
make it easier to launch spacecraft to Mars "and beyond."  But will it?

I believe that one of the arguments is that it takes X amount of fuel to go from
Earth to Mars, but only Y amount of fuel to go from Earth to the Moon and only Z
amount (i.e., less than X) to go from the Moon to Mars.  Dubya seems to be
suggesting that, in lauching from the Moon to Mars will use only Z amount of
fuel and will therefore be more efficient than an Earth-based launch.

Here's my quandary:  Don't we still need to transport the fuel from Earth to the
Moon, and doesn't it take fuel to get there?  If so, is this really more
efficient?  If so, it is sufficiently more efficient to justify a multi-billion
dollar construction project on the Moon?

Boost the fuel (and oxidizer) from earth?

Fuel maybe, oxidizer no.

The moon has among its most common elements: oxygen, silicon and aluminum

Solar cells can be made from silicon and aluminum + trace elements. Just add
energy. (and technology that you brought with you)

Rocket fuel can be made from aluminum dust. Just add energy (and ditto)
Rocket oxidizer can be made from oxygen. Just add energy (and ditto)

The moon gets 2 weeks solid non stop sunshine a month, with no clouds to get in
the way. That's a lot of energy.

Proposals I have seen for using a moonbase as a true BASE involve setting up
automated manufacturing operations on the moon... send a small plant up that can
make solar cells, use it to bootstrap up to a larger plant that makes solar
cells, use that to bootstrap up to a plant that makes rocket oxidizer and fuel.

If aluminum dust fueled engines are too far out, you still can get a lot of
savings from making the oxidizer locally, even if you brought the fuel with you.

OR... build an electric catapult to get things into low lunar orbit, then switch
to ion drive, which is electric (and thus non chemical and thus much higher
specific impulse). Aluminum ions or oxygen ions would work fine.

Okay, that's pretty cool (but you lose points for using "bootstrap").  I was
only thinking of vehicles launched from Earth and using the Moon as a
waystation, rather than craft built in orbit or on the Moon.

But wouldn't it be monstrously expensive to build such a manufacturing facility
on the Moon in the first place?  Unless the moonbase is an end unto itself
(rather than being solely a stepping-stone to Mars), would it be more
economically sensible to construct a lunar base or simply to go straight to
Mars?

Of course, if there are other benefits to a lunar base, all the better.  But I
guess I'm having trouble getting all the numbers to line up.

Thanks all the same.

Dave!



Message has 1 Reply:
  Re: We're here to go
 
(...) Um, no I don't. And stop resetting the FUT back to geek. (...) For NASA, sure. They blew 100B on something that could have been built out of spent shuttle fuel tanks if they had spent about 100M early in the program. For Burt Rutan, no. (or (...) (21 years ago, 17-Jan-04, to lugnet.off-topic.geek, lugnet.off-topic.debate)

Message is in Reply To:
  Re: We're here to go
 
(...) Boost the fuel (and oxidizer) from earth? Fuel maybe, oxidizer no. The moon has among its most common elements: oxygen, silicon and aluminum Solar cells can be made from silicon and aluminum + trace elements. Just add energy. (and technology (...) (21 years ago, 16-Jan-04, to lugnet.off-topic.geek, lugnet.off-topic.debate)

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