Humidity control continues to be a major concern in the Space Shuttle Program (SSP) and International Space Station Program (ISSP), affecting crew comfort and potential unwanted condensation. All analyses regarding these concerns depend on crewmember respired and perspired water vapor generation rates. However, there appears to be wide variation throughout the Environmental Control and Life Support (ECLS) community regarding the assumptions of these water vapor generation rates.
A study was conducted that includes a survey of past studies accomplished in terrestrial and microgravity environments, with data gathered from SSP, ISSP, and Mir missions. Subsequent data and independent conclusions suggested by SSP and ISSP flight data will also be examined. Analysis of water used by the Orbiter Flash Evaporator System (FES) and crew, condensate collection, urine collection, and dry bulb temperature, humidity, and carbon dioxide concentration measurements will be employed to complement the former studies.
It is anticipated that analysis of past studies and subsequent flight data will help define the most appropriate values for crewmember water vapor generation rates at expected cabin environment conditions during future SSP and ISSP missions.