Ok, radiation shielding is necessary *anywhere*

--- In spacesettlers@egroups.com, "Darren Brown"

> What happens to the excess heat or do you need to supply
heat?

If we're talking about the solar-powered habitats of O'Neill, we'll
need to dump excess heat. Fans circulating air through metal
radiators should be sufficient.

> Where does the sewerage go and what happens to it?

To the CELSS of course. We just try not to think about it too much.
:)

Another alternative was proposed by Marshall Savage. He recommended
use of a super-critical combustion chamber to combust sewerage down to
simple compounds, which would then go into the CELSS. It's just a
choice between using microorganisms to do the job, or using the
machine Savage recommends.

> What do you
> produce and who buys it? How do you get it to your customers?

I get lots of arguments from Mars advocates, but I still say SPS is a
plausible export for orbital settlements, and Earth is the market for
it. O'Neill was intelligent and practical enough to know that his
vision of orbital habitats would not be realized until he could
identify a market better served from space than from Earth, and I
think he correctly identified it. When I ask what market is better
served from Mars than anywhere else, I just get told that exports
aren't really all that important, and money isn't everything.

The thing I like about SPS is that the customer being served is Earth.
I can't seem to convince Mars advocates that the first customer for
our products has to be Earth people. They don't seem to understand
that saying the justification for settling Mars is to serve the
markets that the Martians will require is a circular argument.

I think O'Neill was correct in saying that the only products better
produced in space than on Earth are orbital assets, but orbital assets
can still be sold to customers on Earth. The beauty of SPS is that
power can be beamed down. I don't have as much confidence in the idea
that anything might be mined in space and then sent down to the Earth,
although I suppose some platinum group metals might be an outside
possibility.

Rgds,
Mike Combs