[Possibility of conserving the heat balance of the human organism in an extremely rarefied atmosphere by vacuum evaporation of sweat from the surface of the body].

As a result of 64 experiments carried out on 24 test subjects, it has been shown that extreme overwarming due to moderate and heavy thermal loads can be prevented with the aid of heat release through sweat evaporation from the surface of the body under the action of a rarefied atmosphere (termed vacuum sweat evaporation). The test subjects wearing altitude suits remained in a thermal altitude chamber at 40 and 55 degrees C for 8 to 3 hours at rest and doing light work at altitudes of 7 to 25 km without marked signs of overwarming. The entire heat release occurred only through vacuum sweat evaporation from the surface of the body that was under the altitude suit during a gradual decrease of the chamber pressure to 20 mm Hg (equivalent to an altitude of 25 km). The findings give support to the hypothesis that heart release via vacuum sweat evaporation from the surface of the body can be used as a method of controlling thermal homeostasis during high altitude and space flights.