Systems supporting human life and survival range from small items like oxygen masks or protective suits to the global biosphere. However, in a long run, the former ones cannot work without proper functioning of the latter. A consequence for biomedical research is the challenge to more fully understand, and to take into account, complex ecophysiological systems interdependencies. The development of life support systems (LSS) as used in manned flight significantly contribute to our understanding of life on a grand scale. A "medium-sized" materially closed LSS model is Biosphere 2, which completely recycles waste, provides clean air, potable water, and nutrient-dense food to a crew of 8 for basically unlimited time.