In 1991, eight people voluntarily sealed themselves inside a three-acre collection of domes for two years, cutting off air, water and food from the outside world.
The volunteers planned to receive everything they needed to survive from inside the glass domes, collectively called Biosphere 2. They grew fruits and vegetables and raised goats and chickens for food. They recycled every drop of water they used—condensing water from the air and reusing waste water for the plants. They didn’t want to take oxygen from the outside world, so Biosphere 2 was totally sealed. It was more airtight than the space shuttle. In order to keep the air inside oxygenated, plants grew everywhere, especially in the rainforest area; the abundant plant life soaked up carbon dioxide.