A survey of some regenerative physico-chemical life support technology

To date, manned spaceflight has used the relatively simple support methodology of bringing all the necessary water, oxygen, and food for the duration of the mission, and collecting and storing waste products for return to Earth. This is referred to as an open system. It was recognized early, as manned missions became longer and crew size increased, that the weight, volume, and transportation penalties of storing or routinely resupplying consumables would at some point become too expensive. Since the early 1960's regenerative ECLSS technology has been under development, and there now exists a foundation in both systems definition and subsystem technology to support long-duration manned missions. In many cases this development has reached the engineering prototype stage for physico-chemical subsystems and in this article some of these subsystems are described. Emphasis is placed on physico-chemical waste conversion and related processes which provide sustenance and not on environmental factors or subsystems, e.g., temperature and humidity control, spacecraft architecture, lighting, etc.