On 26 September 1991, eight people locked themselves inside a three-acre world of glass and steel in the Arizona desert — and two years later emerged gaunt, oxygen-deprived, and having discovered that the building's own walls had been slowly stealing the air

On 26 September 1991, eight people locked themselves inside a three-acre world of glass and steel in the Arizona desert — and two years later emerged gaunt, oxygen-deprived, and having discovered that the building's own walls had been slowly stealing the air

On 26 September 1991, eight people entered Biosphere 2, a sealed glass and steel structure in Oracle, Arizona, built to test whether a human-made ecosystem could keep people alive for two years. The building was not a spacecraft, but it was a serious rehearsal for one of the hardest questions in space settlement: whether air, water, food, waste, soil, plants, animals, machinery, and human behaviour could be made into a working loop. The Universi…