[extropy-chat] SPACE: Back to the Moon (?)

[Robert J. Bradbury]

On Thu, 30 Oct 2003, Brian Shores wrote:

> I've heard some ideas a while back about making some form of concrete
> with the regolith... maybe they could mix some nice polymers in with it
> and also make it sprayable and just spray it over the module shells?

Why not a simple production plant to crank out either sheet silicon
or titanium -- plenty of both up there.  Welding titanium is a bit
tricky but ought to eliminate the loss of gas problem Eugen was
discussing.  Since you have to separate O2 from the Si/Ti anyway,
it isn't going to be the problem.  Its N2 that is going to be the
problem.  Now of course one could substitute He3 which there is
a fair amount of and one wants to mine anyway for its use in fusion
reactors.  Downsides would be that the astronauts would talk funny
and He3 is moderately radioactive.

> Would some kind of electromagnetic shielding help in any way versus
> radiation, assuming one could be developed that was powerful enough? Is
> it really just high energy emissions people are most worried about? This
> is a bit out of my experience here, any ideas? :)

I'm reasonably certain that normal plasma coming off the sun (the solar
wind) as well as coronal mass ejections (which have been in the news
of late) are largely positively charged ions (solar surface temperatures
are more than hot enough to remove a significant number of the outermost
electrons from most elements).  Whether or not the electrons get thrown
off too and they effectively recombine to form neutral atoms I'm a bit
unsure of (I would suspect the probability is low).  So it seems probable
that with a big enough electromagnetic shield one should be able to deflect
many of the particles.  [Seems to me like the Earth's magnetic field functions
in this way for us.]  Amara might know more.  How difficult it would be to
produce such a magnetic field I don't know.

While effective against charged particles I don't think a magnetic shield
isn't going to help you with gamma rays -- but I don't think the sun emits
many of those.

Worth noting is that I believe the best radiation shields require the
greatest neucleon density -- that means most probably either hydrogen
or better yet deuterium.  So one is going to want to separate them from
any ice that is available and put the habitats underneath liquid H2 lakes.

R.