Space Station Environmental Control and Life Support System Distribution and Loop Closure Studies

The space station environmental control and life support system (ECLSS) is divided into seven functional groups: temperature and humidity control (THC), atmosphere control and supply (ACS), atmosphere revitalization (AR), fire detection and suppression (FDS), water recovery and management (WRM), waste management (WM), and EVA support (ES). This paper addresses the distribution among the modules of the ECLSS subsystems within each of these groups, both in terms of physical and functional distribution. The module resource requirements and safety implications, particularly with regard to safe haven operations are discussed. The implications of subsystem sizing are also addressed. The major recommendation is to physically distribute, but functionally centralize the air revitalization and potable water reclamation systems, while sizing each of these subsystems to support a six person crew under emergency conditions. This paper also addresses the degree of loop closure of the oxygen and water reclamation loops for the IOC space station. The primary tradeoffs are the additional resupply requirements for opening the loops as opposed to the additional development costs and risks associated with the loop closure options. Closure of both the oxygen and water recovery systems are recommended for the IOC space station.