The boldest human experiment of the last century?

When an intrepid crew of eight entered Biosphere 2, a giant air-tight greenhouse in the Arizona desert in September 1991, no one knew how it would pan out. It was an experiment to see if humans could live in similar glass worlds on other planets. Their intention was to survive by cultivating the farmland and plant life inside to create the food and oxygen they needed, but quickly both ran dangerously low. This is the story of how original 'Biospherians' Mark Nelson, Sally Silverstone, Jane Poynter and Taber MacCallum endured what's been called one of the most audacious, unusual and controversial experiments of the last decade. Mark Nelson and Sally Silverstone have released a new edition the book they wrote whilst inside Biosphere 2 called 'Life Under Glass: Crucial Lessons in Planetary Stewardship from 2 Years in Biosphere 2'. Presented and produced by Saskia Edwards Additional production by Mariana Des Forges Picture: The original crew outside Biosphere 2 Credit: Getty Images