Billy Brown writes:
> I think you both overestimate the problem. Building a 'natural'
> biosphere is well beyond our current knowledge, but we don't need
> to do anything of the sort for life support. Providing air, water
> and climate control requires only mechanical systems and a decent
> energy source. Providing food is simply a matter of growing crops,
> which is something we do know a lot about.
Ask the cosmonauts how they and everything they were living among smelled after the end of a long stay in Mir. (If you can't find a cosmonaut, ask a sailor who has done a long tour of duty on a nuclear submarine.) Foul air is an unsolved problem for long-term missions. Biosphere 2 experienced no foul air problems (although there was that bit about uncured concrete stealing the oxygen) although earlier biosphere closures had, because they pumped their air through a soil bed with a variety of carefully chosen bacterial cultures growing in it.
As we extend human presence in space to larger populations and longer stays, more problems of this kind are going to come up. Your assertion about "mechanical systems and a decent energy source" has *never* been tested in a closed biosphere with a large human population over a long period of time, and I see no reason to accept it in advance of such testing. Don't confuse wishful thinking with practical optimism.
> Mind you, I do think we would be wise to do everything we can to
> maximize the colony's resources in this regard. We should take
> along a good assortment of experts in related fields, as well as
> a good variety of plant and insect species (no 'one person growing
> one crop' scenarios, please - we don't want the colony to fail
> because we happened to pick the one plant that doesn't adapt well
> to low gravity). However, I see no reason to think that moving
> food production into space will be anywhere near as difficult as
> creating an entire biosphere.
The setup you propose with its "mechanical systems" *is* a biosphere which will have to be created, so of course moving self-sustaining food production into space will be exactly as difficult as creating an entire biosphere. The question is, will the biosphere you create succeed or fail, over the long term, in supporting the lives of a human society or not.