System Level Water Balance for Space Station Freedom

As a result of a 1989 program rephasing, Space Station Freedom's system-level water balances have been materially shifted. The average and the most likely values of the water balance, and the components of variability, were evaluated in this study. The Assembly Complete configuration has a large excess of ECLSS potable water but a deficit of ECLSS hygiene water. In contrast, there is a small ECLSS potable water deficit but an excess of ECLSS hygiene water for the “Permanent Manned Capability” (PMC) configuration. Upon considering the Orbiter fuel cell water supply to the station and the combined demands for station water, the average and most likely values for the overall excess quantity are 6,800 and 9,000 pounds per year for the Assembly Complete configuration. Comparable values for the PMC configuration are 6,600 and 6,400 pounds per year.