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During EVA and other extreme environments, mutual human support is sometimes the last way to survive when there is a failure of the life support equipment. The possibility to transfer a warming fluid from one individual to another to increase heat and support the thermal balance of the individual with system failure was assessed. The following analog scenarios were considered: 1. one subject has a cooling system that is not working well and already has a body heat deficit equal to 100-120 kcal and a finger temperature decline to 26-27ºC, the other subject is at comfort level; 2. one subject is overcooled due to system failure and the other is mildly overheated. Preliminary findings showed promise in using such thermal sharing tactics to extend the time duration of survival in extreme situations when there is an increased metabolic rate in the donor.

The focus of this research is on the development of a more energy efficient shortened liquid cooling/warming garment (LCWG) based on physiological principles comparing the efficacy of heat transfer of different body zones; the capability of blood to deliver heat; individual muscle and fat body composition as a basis for individual thermal profiles to customize the zonal involvement of the garment; and the development of shunts to minimize or redirect the cooling/warming loop for different environmental conditions, physical activity levels, and emergency situations. The total length of tubing in the LCWG is approximately 35% less, and the weight decreased by 45% compared to the LCVG currently used in space.

The maximal capability of several body areas to absorb/release heat by varying the circulating water temperature in different zones of a multi-compartment liquid cooling/warming garment (LCWG) was explored. The goal was to identify the areas that are highly effective to stabilize body comfort, and to use this information for developing a more physiologically-based design of the space suit. The results showed a high capability of the upper compared to the lower body in the conductive heat exchange process. The involvement of the head in this process is still problematic, because there was not a high level of direct heat absorption/release through the cooling/warming hood in the LCWG. Exclusion of the legs but with involvement of the feet in heat exchange had no effect on comfort of the distal parts of the extremities and core body status.

This pilot study explored the effectiveness of local wrist warming as a potential countermeasure for providing finger comfort during extended duration EVA. Four subjects (3 males and 1 female) were evaluated in three different experimental conditions. Two additional body surface and wrist thermal conditions were evaluated on a smaller number of subjects. Wrist warming significantly increased finger temperature in ambient temperature. A clear positive effect to the fingers was evident when total body heat deficit was 30% of basal metabolic heat production in resting conditions. These initial findings indicate that wrist warming has considerable potential for increasing astronaut comfort during EVA while decreasing power requirements.