Trade Study of an Exploration Cooling Garment 2008-01-1994

A trade study was conducted with a goal to develop relatively high TRL design concepts for an Exploration Cooling Garment (ExCG) that can accommodate larger metabolic loads and maintain physiological limits of the crewmembers health and work efficiency during all phases of exploration missions without hindering mobility. Effective personal cooling through use of an ExCG is critical in achieving safe and efficient missions. Crew thermoregulation not only impacts comfort during suited operations but also directly affects human performance. Since the ExCG is intimately worn and interfaces with comfort items, it is also critical to overall crewmember physical comfort. Both thermal and physical comfort are essential for the long term, continuous wear expected of the ExCG.

The subsystems and design considerations that were studied include the amount and placement of cooling, the ventilation system, the carrier structure in terms of the number and configuration of garment components, garment materials, the cooling line configuration, ancillary equipment, water connectors, and a bio-medical harness. The guiding principle of the ExCG system is the physiological design of cooling. Based on this study, it is recommended that the ExCG be configured as a one piece garment with physiologically placed cooling lines on the head, back, top of the shoulders, ribs, lower arms, inner thighs, and calves. Placement of tubing in these physiological zones was based on the results of a cooling analysis and crew survey. An optimal cooling line configuration was selected through analytical and experimental investigation of different materials, tube geometries, and tube routing. An assessment of the ventilation system, beginning with a historical perspective and considering a wide range of options including a vent system on the pressure garment, concluded that a vent system should be integral with the ExCG. Materials were selected based on the mapping of material functionality of different physiological zones.

This paper will discuss the recommended ExCG system concept and its expected ability to meet goals and requirements described in the Crew, Robotics, and Vehicle Equipment (CRAVE) delivery order (DO 25) for the ExCG. This concept will maintain crew thermal balance and physical comfort while simplifying ExCG operations and logistics.