Tolerance of G-Loads by a Russian Cosmonaut and a NASA Astronaut during the Soyuz Space Vehicle De-Orbit after a 340-Day Mission to the International Space Station

Abstract

Tolerance of the chest-to-back (+Gx) loads aboard the Soyuz transport vehicle was evaluated for the first time in the Russian cosmonaut (55 years old, second mission) and NASA astronaut (51 years old, fourth mission) during de-orbit after a 340-day mission on the International Space Station (ISS) in 2015–2016. According to the analysis of subjective sensations and objective physiological data, the G-tolerance of the Russian cosmonaut was satisfactory. However, it is pertinent to note that at the landing site he exhibited momentary symptoms of orthostatic instability including “the gray-out” when rising to his feet that usually precede syncope, as well as salient vestibular symptoms such as vertigo, nausea, difficulty maintaining balance, locomotor ataxia during walking and the feeling of general discomfort that all suggest decline of G-tolerance in comparison with the results of preflight G-testing. Since 2009 astronauts have not been interviewed or examined immediately after landing, and for this reason G-tolerance of the NASA astronaut was evaluated as satisfactory based on analysis of objective physiological information only.