Hi p

Hard to write when you're dead.

I think you figured out my basic point - that maybe we should be planning on going to Mars in a big way. But a precondition of that would be massive space-habitats and it's hard to see them arriving soon. I would say that Space Elevators or ultra-cheap HLLV (positron energised rockets?) are the necessary precondition for that.

Yet Anthony Zuppero's ice ships have a real appeal for bulding big habitats. He proposes using either Lunar, or dead comet, ice made accessible by relatively low temperature (1900 K) nuclear thermal rockets. Ice would be both structural and shielding material filling double-walled inflatables.

Makes sense and uses easily processed materials already in space.

Adam