Yesterday we went to the Biosphere 2 in Tucson. We've talked about going for awhile so it was great to finally check it out. It's an amazing piece of architecture and engineering. It was designed to be a closed off ecosystem, so the huge complex (over 4 acres) is enclosed in sealed glass and the foundation is lined with solid steel. It is completely air proof and requires two geodesic domes called "lungs" on each end to provide a flexible membrane air compression so that the building does not explode or implode under changing air pressures. There are three main areas, a tropical forest with a tropical coral ocean, a desert, and a farm and living area. At one point, people tried to live inside with no help from the outside world, but had a problem with global warming because the plants could not keep up with their oxygen needs (the building was absorbing it) and had to have oxygen pumped in. We went on a guided tour through the whole place, examining a lot of the high technology that such a place requires. Then we explored on our own.
This was worth the hefty admission price. I recommend going if you haven't seen it. The Discovery Channel voted it 3rd most impressive human engineering accomplishment..
