Liquid Cooling and Ventilation Garment - Space Applications

Space Applications

Astronauts commonly wear a Liquid Cooling and Ventilation Garment in order to maintain a comfortable core body temperature during extra-vehicular activity (EVA). The LCVG accomplishes this task by circulating cool water through a network of flexible tubes in direct contact with the astronaut's skin. The water draws heat away from the body, resulting in a lower core temperature. The water then returns to the Primary Life Support System (PLSS), where it is cooled in a heat exchanger before being recirculated. In an independent space suit, the heat is ultimately transferred to a thin sheet of ice (formed by a separate feed water source). Due to the extremely low pressure in space, the heated ice sublimates directly to water vapor, which is then vented away from the suit. In a dependent space suit (such as the ones used in the Gemini program or within lunar orbit on the Apollo program), the heat is carried back to a host spacecraft through an umbilical connection, where it is ultimately radiated or sublimated via the spacecraft's own thermal control system.

Because the space environment is essentially a vacuum, heat cannot be lost through heat convection, and can only be directly dissipated through thermal radiation, a much slower process. Thus, even though the environment of space can be extremely cold, excessive heat build-up is inevitable. Without an LCVG, there would be no means by which to expel this heat, and it would affect not only EVA performance, but the health of the suit occupant as well. The LCVG used with the Apollo/Skylab A7L suit could remove heat at a rate of approximately 586 watts.

The LCVG used with NASA's Extravehicular Mobility Unit is primarily constructed of spandex, with a nylon tricot liner. The tubes are made of polyvinyl chloride.