On Oct 18, 11:45 pm, Quadibloc wrote:
On Oct 17, 12:56 pm, Hop David wrote:

I agree moon habs will have lower start up costs. But why would Martian
habs be less expensive than NEO based habs? There are NEOs that can be
reached with less delta vee than Mars and with launch windows of
comparable frequency.

The start up cost of a small Martian habitat would be larger, since
initial supplies would be launched from Earth.

But the cost of expanding the habitat, while it would still be larger
than costs of Earth habitats - they would have to be airtight -
doesn't involve gallivanting around the Solar System to pick up
asteroids for metals and comets for volatiles. Surface transport will
do.

John Savard

In zero-g, you could probably use some kind of Venetian glass-blowing
technique to inflate a large pressure vessel from molten steel. A
little axial rotation would get you a disc shape, a little tug on the
ends would get you an ellipsoid. O'Neill suggested a magnetised steel
spray.

Yes, getting materials from other asteroids is trickier than scooping
them up with a rover but it can be done. Raw materials could be
supplied by unmanned solar sail craft scooping it off other asteroids,
if absolutely necessary. However, I believe the idea is to go
prospecting for one with the right mix of materials.

Sure, Mars and NEO are different, but I don't see them as having to
necessarily compete. But somebody, sooner or later will start to
utilise NEOs. NASA can go off and set up Mars colonies (actually the
Russkies are more apt to do that), Japan can build SPS, ESA can
develop the moon and India or China or private companies can go haring
after space rocks.