Biosphere 2 is located north east of Tucson at the base of the Catalina Mountains. It was built in the late 80s and the first and only human mission was a 2 year project in 1991 - 93.
Biosphere 1 is the earth itself - a God created totally sustainable environment where humans and animals exist in a perfectly balanced world.
The project was moderately successful but in many ways it failed. The concrete that it was built on continued to cure for many years and it stole oxygen out of the sealed environment through the soil. Normal O2 levels are 21% but it dropped to 15% over the 2 years of the experiment. Also, the fruit trees and other plants that were brought in, had bugs and pests that multipled and affected the food production. All the scientists lost weight and were malnourished. The 8 people working inside also had personality clashes that made their life difficult. When the door was opened at the end of the 2 years, they were all glad to leave!
Now, Biosphere 2 is owned and operated by the University of Arizona and many environmental experiments are going on there but it is no longer a closed and sealed place. We had a wonderfully informative tour by a guide who knew the place very well.