[stcredzero]

I suspect hermetically sealed enclosed mini ecosystems are going to take on tremendous economic and technological importance as we move out into the solar system.

I've started to wonder why there aren't more closed loop experiments out there. These would be very cheap to make! (By space research standards.) A closed water loop habitat could be built in the middle of isolated land, like West Texas. Go from there to incrementally incorporating more of an ecosystem. Try and recycle the air last, of course, as that is potentially life threatening.