Bob: I didn't mean to say that we can make such Biospheres NOW. What
I meant was that if we had the technology to make closed ecosystems in
space it would still be much much cheaper to build them on earth.
As for materials, there are plenty of materials in space. Asteroid
mining only makes sense if you decide to stay in the asteroid belt and
set up shop there. It makes no sense to try to bring megatons of
metals back to the earth's surface, especially since the earth is
mostly made of metals. All we have to do is process it, and all this
takes is energy. And anyway, how much metal do we need? Our standing
stock of metals is getting higher and higher, metals have always been
recycled throughout history.
Suppose someone brought back a metal asteroid, and brought all the
metal back to earth's surface. Well, metal prices would drop like a
rock. But how much of an advantage would that be for our global
civilization? Metal prices have been declining for decades, there
isn't a metal shortage, we aren't starving for metals.
The real use for these asteroids is in space. As Bob pointed out,
there aren't a lot of building materials in earth orbit. Well, keep
the asteroids in earth orbit. However, I bet that we will never allow
people to regularly bring asteroids near earth due to the catastrophic
consequences of a parking accident. So asteroid mining and
terrafroming will have to be done away from earth.
And I agree with Christopher that Biosphere II was not really a
failure. It didn't demonstrate what the builders hoped it would
demonstrate, but we did learn a lot from it. Perhaps the same amount
of money spent on less grandiose projects would have been wiser, but it
wasn't a complete waste. Has it been conclusively decided whether the
dropping oxygen levels were due to concrete curing or very organic
soils?
But anyway, consider this. Biosphere II cost millions of dollars, and
was only able to keep a half dozen people alive for a year or so as
long as they worked like dogs farming and maintaining the machinery and
if they could get shipments of extra raw materials. I would imagine
that space stations would require similar efforts. For the next
hundred years or so biospheres are going to be experimental, hugely
capital intensive, and a huge amount of work.
=====
Darryl
Think Galactically -- Act Terrestrially
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