Interior of Biosphere 2, a laboratory for global ecological research, under construction.

The Biosphere 2 project in Arizona was one of the most advanced scientific experiments of the late Twentieth Century. Simply put, the project aimed to create a completely sealed ecological system containing several of the major tropical biomes found on Earth. (The Earth biosphere, Biosphere 1, was the only biosphere known to man until the creation of Biosphere 2.) An engineering marvel in its own right, the 3.5 hectare footprint facility was the most tightly-sealed structure ever built. Inside, sealed off from contact with the outside world, were housed a rain-forest, a coral reef, a savannah, a marsh, a desert, a human habitat and an intensive agricultural and farm area, that was to provide food for the eight human occupants of the first two-year experiment. Biosphere 2 was a laboratory for the study of global ecology and was designed to last for one hundred years with rotating human 'crews.' The aim was to study the complex processes of self-organisation in the biosphere and to pioneer new systems for air, water and waste-water recycling and sustainable agricultural systems.