Biosphere 2

In 1991, four men and four women entered the Biosphere 2, an airtight, self-contained structure in Oracle, Ariz., where they would live for two years. The 7,200,000-cu-ft sealed glass and space-frame structure contained 5 biomes, including a 900,000-gallon ocean, a rain forest, a desert, agricultural areas and a human habitat. It was built in the late 1980s with $150 million in funding by Texas oil magnate Edward Bass. Biosphere 2 was designed as replica of Earth's environment (Biosphere 1). During their stay, the crew experienced various problems. Limited agricultural productivity restricted their diet. Micro-organisms in the soil reduced oxygen levels in the atmosphere and added nitrous oxide. The crew emerged on 26 Sep 1993. Unfortunately, the problems with the project's results brought scientific disdain.«