Planet in a bottle. Eden revisited. Laboratory under glass. The largest self-sustaining closed ecological system ever made. Biosphere 2 is many things to many people. From its half-acre farm to its coral reef to its emerald rainforest—this unique research facility has proven itself a marvel of human engineering and a testament to the human imagination. For two full years from 1991 to 1993, four men and four women lived and worked inside the structure, recycling their air, water, food, and ...