🚀 go-pugleaf

In article <19070@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes:

> density of about 2700 kg/m^3 will require small tanks.  The tanks are very
> hot, meaning that little mass of pressurization gas will be needed.  A useful
> technique might be to have the molten aluminum stored in a spherical steel
> tank pressurized by injecting liquid nitrogen into the tank (which because of
> the heat will immediately vaporize).  Is nitrogen available from the moon?


Hydrogen or helium could work.  If the tank is at 1000 K, and the tank
pressure is 2 MPa, one needs about 1 gram of hydrogen for every 5000
grams of aluminum.  Producing a gram of aluminum requires the
processing of about 10 grams of anorthite.  So, if the anorthite has
at least 20 ppm hydrogen (implanted from the solar wind) , this
byproduct would be sufficient to provide pressurizing gas (actually,
since there will be an excess of oxygen in the rocket, still more
regolith would have to be processed, so still more hydrogen would be
produced).  No need to liquify it, just store at high pressure.

Water might be more convenient, although I expect steam would react
with the aluminum (not necessarily a problem, unless the aluminum
oxide byproduct clogged things).

	Paul F. Dietz
	dietz@cs.rochester.edu