Performance of the Shortened Liquid Cooling Warming Garment During Simulated MicroG EVA

Surface temperatures during extravehicular activity (EVA) in low Earth orbit range from -157°C to 121° C. Although spacesuits shield astronauts from such inhospitable extremes, metabolic heat production due to physical exertion is trapped within the garment, leading to increased internal temperature. Cooling garments are utilized to maintain human thermal equilibrium.

NASA's Liquid Cooling and Ventilation Garment (LCVG) has been in use for decades. Koscheyev and colleagues developed a physiologically designed Shortened Liquid Cooling Warming Garment (SLCWG) at the University of Minnesota, focused on increasing the efficiency of the garment to support thermal balance. The performance capability of the SLCWG to remove excess metabolic heat during EVA was assessed by comparison with the LCVG and via metabolic heat development models. The SLCWG findings demonstrated similar thermal balance management and higher subjective comfort ratings compared to the LCVG.

However, the SLCWG has not been tested with subjects in a pressurized spacesuit. The current study assessed the thermoregulatory performance of the SLCWG within a pressurized spacesuit during a simulated microgravity EVA. Test subjects are suspended using the DL/H-1 spacesuit within a horizontal harness system while they perform a number of tasks comparable to the ones performed during microgravity EVAs. Performance of the SLCWG is then judged based on skin temperature measurements, calculated core body temperature, and subjective thermal comfort ratings. Based on data retrieved during the control phase, common metabolic heat development models are evaluated and a metabolic heat development model for the DL/H-1 spacesuit is created.