The Biosphere 2 Project buildings. Biosphere 2 is a privately-funded experiment, designed to investigate the way in which humans interact with a small self-sufficient ecological environment, and to look at possibilities for future planetary colonisation. The $30 million Biosphere covers 2.5 acres near Tucson, Arizona, and is entirely self- contained. The eight 'Biospherians' share their air- and water-tight world with 3,800 species of plant and animal life. Intended for a two-year isolation, the project has allegedly had problems with oxygen levels and food supply, and has been criticised over its scientific validity.