From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Thu Jul 22 1999 - 14:24:03 MDT
mark@unicorn.com writes:
> Spike Jones [spike66@ibm.net] wrote:
> >Ya, but our chances of making indigenous fuels muuuuch better
> >on Mars than on the moon. The moon is both carbon
> >poor and hydrogen poor.
Well, there seem to be at least 20 Mt water buried at the
pole(s). Let's await the Lunar Prospector crash, perhaps if we're
lucky we'll see some water spectroscopically.
Using it for fuel would be somewhat wasteful, though. Otoh, there is
no telling how much water ice a comet core has, the difficulties to
capture it and spin it down to lunar surface are not so very small
however.
> As of a couple of years ago the leading contendor was a mixture of aluminum
> powder and liquid oxygen; it's not very efficient, but good enough to get
> you to lunar orbit and/or heading back to Earth with a reasonable mass
> ratio.
The very best fuel on the Moon is obviously a linear motor/mass
driver. One needs to make a ramp (using the best angle, which?) out of
regolith/solar-oven made regolith glass bricks, and create a means of
fabricating PV arrays (maybe just sputtering appropriately doped (made
in situ or imported) silicon on lunar soil glass panes, which can be
made by melting the surface of finely powdered regolith, giving time
to anneal/cool and then simply lift them off the powder surface). I am
not sure if lunar soil (without adding cryolith) is suitable for melt
electrolysis, one can certainly use hydrogen (from polar ice)
reduction to get at the iron (see according NASA papers).
Another nice point about a linear mass driver is that in the simplest
implementation it is just a linear array of identical modules:
solenoids, high-voltage capacitors and control logic (could be made as
"vacuum tubes", as even process-contaminated vacuum is probably better
than what is inside your CRT). Optimal for automated
mass-production. With time doubtlessly different techniques will be
developed: wet metallurgy, electron beam ovens, massively parallel
preparative mass spectroscopy for separation, on the long run even
nanotechnological methods, which would be obviously best.
By firing 10 kg packets each minute it could put 14 t/day, or 5
kT/year of material into orbit. And I guess these are very
conservative estimates.
What most astonishes me most is how little attention this angle of
attack receives. Space simulator chambers are a lot cheaper than
shooting the stuff in orbit to test. Also, Earth gravity arguably
reflects lunar situation better than microgravity conditions (these
will be necessary for asteroid processes though).
A lot of xenon lights in a big chamber with simulated regolith, with
an array of cryopumps and lots of remote-controlled micromechanics and
MEMS machinery could be a veritable testbed for developing lunar
tech. Would also be useful for popularisation, transmitting video from
the inside & allowing yokels to test-drive the machinery remotely via
the Internet.
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