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Space suits for advanced missions have baselined radiators as the primary means of heat rejection in order to minimize consumables and logistics requirements. While radiators have been used in the active thermal control system for spacecraft since Gemini, the use of radiators in spacesuits introduces many unique requirements. These include the ability to reduce the amount of heat rejection when overcooling or overheating of the crew member is a concern. Overcooling can occur with low metabolic rates, cold environments or a combination of the two, and overheating can occur with high metabolic rates in a warm environment. The main goal of the Radiator Advanced Demonstrator (RAD) program is to build and fly a radiator on the current Extravehicular Mobility Unit (EMU) in order to verify thermal performance capabilities in actual flight conditions. The RAD incorporates an aluminum plate separated from the primary water panel with a silicone gasket.

During extravehicular activities (EVAs) it is crucial to keep the astronaut comfortable. Currently, a sublimator rejects to space both the astronaut's metabolic heat and that produced by the Portable Life Support System. In doing so, it consumes up to 3.6 kg (8 lbm) of water; the single largest expendable during an eight-hour EVA. While acceptable for low earth orbit, resupply for moon and interplanetary missions will be too costly. Fortunately, the amount of water consumed can be greatly reduced if most of the heat load is radiated to space. However, the radiator must reject heat at the same rate that it is generated to prevent heat stroke or frostbite. Herein, we report on a freezable radiator and heat exchanger to proportionally control the heat rejection rate.

This paper presents the analysis findings of a study reducing the overall mass of the lightweight liquid cooling garment (LCG). The LCG is a garment worn by crew to actively cool the body, for spacesuits and launch/entry suits. A mass reduction of 66% was desired for advanced missions. A thermal math model of the LCG was developed to predict its performance when various mass-reducing changes were implemented. Changes included varying the thermal conductivity and thickness of the garment or of the coolant tubes servicing the garment. A second model was developed to predict behavior of the suit when the cooling tubes were to be removed, and replaced with a highly-conducting (waterless) material. Findings are presented that show significant reductions in weight are theoretically possible by improving conductivity in the garment material.