Shell worlds

On 10/11/13 12:19 AM, Combs, Mike wrote:

> Good points. Plus, when it comes to radiation shielding, anything over
> 2 meters is overkill.

2 meters is sufficient, but more is better. Where I live, 5000 feet
above sea level, the radiation protection provided by the atmosphere is
considered "good enough" -- but I certainly wouldn't object to more.

> I hear people talk a lot about lunar lava tubes.
> But just dig a shallow trench in any desired location on the surface,
> lay your prefabricated module down in it, and then pile on 2 meters of
> regolith, and youre all set for radiation protection, micrometeoroid
> protection, and thermal insulation.

I can't fault the logic of this. If you have the earth-moving (erm,
regolith-moving) equipment, and are building on a small to moderate
scale, then this is a sensible way to go.

On the other hand, I find the idea of lunar lava tubes very attractive
because they're BIG. You could have structures walls of reasonable
thickness, and windows. Granted, the windows wouldn't look out on too
much of a view -- but you could at least see the rest of the settlement,
whatever's being projected on the walls and ceiling of the tube, and how
the new building is coming. I think it'd be enough to give a feeling of
normalcy, and avoid the feeling of being a mole in a hole.

Moreover, it *might* be practical to cap a section of a lava tube,
perhaps spray some sort of sealant on the inside walls, and pressurize
the whole thing. Then you have a *huge* outdoorsy-feeling space, in
which you could build houses separated by little paths and picket
fences. I don't know if anybody's ever done a rigorous study of this
idea, though. (Al?)

Best,
- Joe