Living inside the glass enclosure known as Biosphere 2 for two years wasn’t easy. If its eight pioneering residents wanted pizza, they had to grow their own wheat and milk a goat for cheese. They contended with thinning air, insufficient food, constant work and, worst of all, each other. Biosphere 2 — an attempt to create an enclosed, self-sustaining environment like Earth’s — was part ecology project and part trial space colony.