Biosphere 2 Going Strong at 20

It's been a long time since the last human residents left Biosphere 2 but there's still plenty of life inside the sealed terrarium in the Arizona desert, the AP finds. The 7.2-million-square-foot facility, set up 20 years ago to see whether humans could create self-sustaining space colonies, is now being used by scientists trying to determine the future of our own planet. Teams of volunteers spent years living inside the Biosphere domes in its early days. The live-in phase ended in 1994, although tourists still turn up expecting to find people living there.

The rainforest inside the Biosphere is flourishing and scientists have discovered at least one plant species inside that has become threatened over the last 20 years. The latest Biosphere project aims to determine how vegetation affects rainwater's journey into the drinking supply. "Our understanding of how ecosystems are coupled to the atmosphere, how they're driven by climate, I mean, these are all issues that we absolutely have to deal with right now," the project's director says. "Biosphere 2's just become more and more relevant to that science through time. We don't have the capability to do this anywhere else." (More Biosphere 2 stories.)