LUNA: Re: indigenous fuels

Eugene Leitl (
Thu, 22 Jul 1999 13:24:03 -0700 (PDT) writes:
> Spike Jones [] 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.