Water Recovery Trades for Long-Duration Space Missions

Water recovery in life support systems is critical for long-duration space missions. Potential sources of recoverable water include humidity condensate, urine, feces, and wet trash. Water can also be recovered from metabolic carbon dioxide when hydrogen is available either as a byproduct of oxygen generation or from storage. An assessment of fecal water recovery is initially presented, including a comparison with baseline storage options that do not recover water. The paper then trades combinations of water recovery approaches for deep space missions considering all of the above sources. The trade study uses equivalent system mass as the primary comparison basis and includes reliability/failure tolerance impacts through the addition of spares. Alternative system sizing approaches are considered in addition to possibilities for dissimilar redundancy.