Decompression Safety of Extravehicular Activities of Cosmonauts: The Ways and Means for Solution

This paper is concerned with preventing decompression sickness (DCS) in cosmonauts during extravehicular activities (EVAs). The reasons of a significant discrepancy between the DCS risk for usual subjects during simulation of EVA in altitude chambers and ones for cosmonauts during real EVA performance are discussed. Presented here are means and methods of DCS prevention which form the basis of the Russian and U.S. protocols of preparing to go EVA. Performed analysis of effect of physical-chemical properties of inert components of breathing mixtures on the rate of washin and washout of these gases from body tissues and on dynamics of tissue gas bubbles shows that it is expedient to use the normobaric neon-oxygen atmosphere in spacecrafts as a means of increase in decompression safety and effectiveness of EVA.