 Between the years 1987-1991, SBV constructed the 7 million cubic foot (3.14 acres) Biosphere 2 in the foothills of the Santa Catalina Mountains in Oracle, Arizona, in the appropriately Mars-like Sonoran Desert.Allen began the first manned Biosphere Test Module experiment in September 1988, residing in the structure for three days, proving that closed ecological systems could work with humans inside and setting a world record at that time.The first crew (four men and four women) sealed themselves inside Biosphere 2 on September 26, 1991, and began a two-year experiment to study how the ecosystems inside the artificial biosphere developed.