[Weightlessness and heat stress on astronauts]

Thermal emergency situations have more than once been encountered since the beginning of manned space flights in 1961. This article contemplates human thermal tolerance in weightlessness as complicated with headward [correction of headword] fluid shifts, plasma volume loss, cardiovascular deconditioning, reduced exercise capacity and energy metabolism changes, etc. With these considerations, it is necessary to further investigate the thermoregulation in spaceflight for the health and safety of astronauts.