Can the Moon be given an earthlike atmosphere?

> My multilayered approach is more appropriate for smaller and earlier
> space colonies in which the mass is just not there yet, and for
> spaceships in which it is necessary to keep the mass down.

Yes, certainly for spaceships radiation shielding is a big and thorny
issue. If the Polywell reactor pans out, we will have plenty of energy
available, so an EM shield might make sense in that case.

For space colonies, though, I think even the early ones will find it
cheapest to just dump a few meters of soil (probably based on lunar
regolith) on the ground deck. If you don't have that, then you're
going to have a hard time growing trees, anchoring flagpoles, etc. And
don't even get me started on an external non-rotating radiation shield.
;)

> Your soil shield is a good idea, but we are still going to need a
> water tank beneath the soil and it could be metal lined with plastic.
> For simplicity we may just go with a porous gravel layer below the
> soil for an aquifer.

I like the idea of an aquifer, but -- why do we need it? I feel I've
missed your point here.

> The soil shield will only work on the outside/bottom of a spinning
> colony. For maximum surface area, I envisioned a long cylinder like
> the alien whale probe in Star Trek IV (Save The Whales). However, it
> was pointed out in another thread that this design is inherently
> unstable, as a long cylinder will tend to spin end-over-end like a
> cheerleader's baton.

Right. I much preferred that geometry too (I even have some fairly
detailed designs of a colony based on it), but alas, it doesn't seem
workable.

> I now envision a double-hulled colony consisting of a cylinder
> containing several spheres. ...
> The cylinder rotates around Shuttle Bay Sphere 0 at a rate that
> simulates 1 gee in Spheres 5a&b. Spheres 3a&b would be at about 1/3
> gee (Martian). Spheres 2a&b would be at about 1/6 gee (Lunar).
> Spheres 1 & 4 are optional.

So this is basically a multi-deck baton design. (What's neat is that
my earlier cylinder design, mentioned above, was also multi-deck, with
a "Martian" and "lunar" deck plus a couple others. That one spun
around its long axis though, which we now know is unstable, unlike
yours.)

I'm not sure I see the point of the spheres, though -- why not just put
in flat decks? Those would be simpler and provide slightly more living
area.

Anyway, you're quite right that in a baton design, soil doesn't help
much with the shielding problem, since most of the radiation would be
coming in from the side. In that case you do need some other strategy
(or combination thereof).

Best,
- Joe

Joe Strout -- joe@...