Biosphere 2 is a 3.15-acre (12,700 m2) structure originally built to be a man-made, materially-closed ecological system in Oracle, Arizona by Space Biosphere Ventures, a joint venture whose principal officers were John P. Allen, inventor and Executive Director, and Margret Augustine, CEO. Constructed between 1987 and 1991, it was used to explore the complex web of interactions within life systems in a structure that included five areas based on natural biomes and an agricultural area and human living/working space to study the interactions between humans, farming and technology with the rest of nature. It also explored the possible use of closed biospheres in space colonization, and allowed the study and manipulation of a biosphere without harming Earth’s. The name comes from Earth’s biosphere, Biosphere 1, Earth’s life system and the only biosphere currently known. Funding for the project came primarily from the joint venture’s financial partner, Ed Bass’ Decisions Investment, and cost $200 million from 1985 to 2007, including land, support research greenhouses, test module and staff facilities.
At a size comparable to two and a half football fields, it remains the largest closed system ever created. The sealed nature of the structure allowed scientists to monitor the ever-changing chemistry of the air, water and soil contained within. Health of the human crew was monitored by a medical doctor inside and an outside medical team.
Biosphere 2 contained representative biomes: a 1,900 square meter rainforest, an 850 square meter ocean with a coral reef, a 450 square meter mangrove wetlands, a 1,300 square meter savannah grassland, a 1,400 square meter fog desert, a 2,500 square meter agricultural system, a human habitat, and a below-ground level technical infrastructure. Heating and cooling water circulated through independent piping systems and passive solar input through the glass space frame panels covering most of the facility, and electrical power was supplied into Biosphere 2 from an onsite natural gas energy center through airtight penetrations.
Biosphere 2 had two closure experiments, Missions 1 and 2. The first, with a crew of eight people, ran for two years 1991-93. Following a six month transition period during which researchers entered the facility through airlock doors and conducted research and system engineering improvements, a second closure with a crew of seven people was conducted March 1994-September 1994. In the course of that second mission, a dispute over management of the financial aspects of the project caused the on-site management to be locked out, and the mission itself to be ended prematurely.
In 1995, Columbia University took over management of the facility for research and as a campus until 2003. In 1996, they changed the virtually airtight, materially-closed structure designed for closed system research, to a “flow-through” system, and halted closed system research. They manipulated carbon dioxide levels for global warming research, and injected desired amounts of carbon dioxide, venting as needed.
By 2006, the property, which is in exurban Tucson, was slated to be redeveloped for a planned community. As of June 5, 2007, the property including surrounding land, totaling 1,650 acres (6.7 km2), had been sold to a residential home developer for US$50 million. A development including homes and a resort hotel was planned for a portion of the land. The Biosphere itself remains open for tours
On June 26, 2007, the University of Arizona announced it would take over research at the Biosphere 2. The announcement ended immediate fears that the famous glass vivarium would be demolished. University officials said private gifts and grants enabled them to cover research and operating costs for three years with the possibility of extending that funding for 10 years.