Space Station Water for EMU? Subscale Sublimator Testing

The current Shuttle EMU (Extravehicular Mobility Unit) uses expendable water to provide cooling to the EMU. For Space Station Freedom (SSF), one potential source of this water is the SSF potable water processor (PWP). Concerns exist about utilizing the SSF water for the EMU sublimator because the SSF PWP effluent may contain low soap concentrations. Traces of soap-like compounds (surfactants) have been shown to affect EMU sublimator performance at low concentrations.

Results of testing indicate that a subscale sublimator functions equally well with both SSF PWP effluent and Shuttle quality deionized water. Furthermore, only minor performance anomalies are observed with water purposely spiked with maximum allowable concentrations of baseline shower soap. Not all surfactants are equally detrimental to sublimator performance. Testing with a full scale sublimator is the next step.