Two books

[snikt]
> I find it very unlikely that the moon can be terraformed (?impossible?),
> which is what I meant by 'long-term' colonization.
>

It is not exactly impossible to terraform the Moon, but I would say that it
is economically unviable in the foreseeable future. How the Moon could be
terraformed? Well, envelop the whole orb with a transparent bubble and cover
this bubble with some transparent material (glass plates or water bags)
while you slowly fill the bubble with an oxygen-nitrogen-CO2 atmosphere.
(The weight of the transparent layer over the bubble would counteract
pressure, so the material of your bubble would not have to be particularly
resistant.) Dump some zillions of tons of water to fill the Maria, colonize
the highlands with plants and animals and, voil, you have a terraformed
Moon. (Well, of course there is the problem of the long day-night cycle in
the Moon. Probably you would have to use genetically altered plants that
have a seasonal cycle of a month instead of a year. Those plants could loose
their leaves and hibernate during the lunar night and then resurrect during
the lunar day. Wild animals, supposing that there would be wild animals,
would have to suffer corresponding alterations.)

While the resources to do such a thing are unthinkable for our Earth-bound
economy, I think that they would be negligible for a space-faring
civilization, after some time. If you have trillions of people in hundreds
of thousands of habitats in the asteroids, then I think that you have an
economy powerful enough to finance projects that look impossibly expensive
for us. The question is: would some spacer investor finance such a project?
(Perhaps to sell real state in the Moon to Earthlings? ;-)

> Although I would think it kind of wasteful to terraform Mars (and it would
> no longer be the red planet, how un-romantic: two planets that look the
> same)
>

Uh, even a terraformed Mars would look very alien. For instance, assuming
that you'll use only the resources already in the planet, then you woul have
probably just a somewhat small sea around the North Pole and perhaps another
one in the Hellas Planum (sp?) - nothing like the oceans in Earth. Probably,
the atmosphere would be very thin, like that in the Andes or in the Rockies,
and there would even be large parts of the planetary surface too high to
have enough pressure. Gravity would be only a third of gee, and people would
walk with a somewhat dreamlike lightness (or clumsiness ;-), while sea waves
and water drops would be huge when compared to their Earth correspondents.
Since the planet would have just small seas, I much doubt that rainfalls
would extend much beyond them, and probably large fractions of the planet
would remain a desert. So, I think that the planet would still somewhat look
reddish, but with some blue and green spots and a lot of cloud clusters...
You would have neither the old Mars nor a new Earth, but something
completely different.

[snikt]
Lucio Coelho