Mocircus than science

On 3/30/06, George Perkins wrote:
>
> Seems the CELSS is a good idea but it's problematic over the long
> term. The real goal is to have it last forever. Even if it worked
> for two years, how do you hotwire a thousand years into it?
(...)

I would not think that the goal of a closed ecosystem in space is to
last "forever". The goal is to last long enough for the maintainers of
the ecosystem to find space resources to replenish losses due to
inefficiencies. Suppose that you live in a mobile space habitat using
a closed "farm" that is guaranteed to recycle your air and water for
two years. That is likely to be more than enough time for you to reach
an asteroid or comet or small orb were you will find volatiles to
replenish losses.

I think that this idea of a closed ecosystem that lasts "forever"
comes from the wrong (but very popular) idea that the global ecosystem
on Earth lasts "forever". The truth is that it does not last forever -
it has a cycle of collapses and then profound transformations. Ice
ages, warm ages, evolution of new lifeforms, all those are factors
able to "reset" our ecosystem. The only difference in relation to a
space habitat is that while an habitat ecosystem may suffer
significant changes in a few years the one in a huge planet will
likely need millenia to show the same effects.