Cosmonauts’ tolerance of the chest-back G-loads during ballistic and automatically controlled descents of space vehicles

Abstract

This paper carries out analysis of cosmonauts’ +G _x tolerance on the stage of ballistic or automatically controlled descent of Soyuz space vehicles after missions to the International Space Station of varying duration. As compared with automatically controlled descents, tolerance of descent re-entry + G _x following short (8–14 days) missions was marked by reliably more frequent instances of visual disorders, difficult breathing, sensation of a lump in the throat, and vestibulo-autonomic disorders (p < 0.05). The ballistic but not controlled re-entry after long-term missions provoked visual disorders, difficulties with breathing and speech, and vestibulo-autonomic disorders more often (p < 0.05). A considerable HR rise at the ballistic rather than control descent was associated with re-entry and main parachute re-hooking for symmetrical suspension; respiration rate was the highest during parachuting. On the whole, these factual data infer that the ballistic descent after various periods in spaceflight microgravity, especially after extended space missions (164–169 days), led to a dramatic loss in the body functional reserves.