Radiator Heat Pump Subsystem for the Space Suit Portable Life Support

The study of conceptual designs for a space suit Personal Life Support Subsystem (PLSS) at the Texas Engineering Experiment Station resulted in the recommendation to NASA of an evolution path from the existing PLSS to a long duration, low mass PLSS suitable for Martian missions. The replacement of the water sublimator cooling unit by a radiator-mechanical heat pump subsystem was one of the key technology upgrades for this evolution. The assessment was based on using a carbon radiator and mechanical heat pump. The “Lunar Noon” environment was used for sizing the system. The effect of lunar dust on the radiator and choice of refrigerant fluid were considered. A survey of previous work on high temperature heat pumps was made in order to estimate the maturation time for the heat pump technology. We concluded that a heat pump radiator using water as its cooling fluid was the best alternative.