Search Results

The risk of decompression sickness (DCS) inherent in extra-vehicular activity (EVA) is reduced through the usage of hypobaric normoxic atmosphere. The safety of decompression protocols was evaluated during EVA simulation in the PCC-270 pressure chamber complex according to DCS frequency and tissue supersaturation ratio. The test program included 15 man rated test runs (1828 man- runs) with 123 test subjects aged 19-54. The aim of the test program was to select decompression safe protocols for transfer from hypobaric environment to a reduced pressure mode in the Russian space suit. These experiments allowed to display in nomogramm form the ratio of operative pressure mode in the extravehicular space suit to the duration of a preliminary exposure in normoxic hypobaric conditions.

The report presents the values of supersaturation ratio expected during space flights in chart form, covering the range 400-950 mm Hg of total atmospheric pressure and 150-400 mm Hg final space suit pressure. These charts allow users to rapidly find decompression risk received in the most critical decompression protocols for extravehicular activity either in nominal situations or during emergency activity. Decompression safety transfer to the reduced pressure has been established as a result of long-standing man rated tests during two decades. Tests aimed at selecting decompression-safe protocols for transition from a hypobaric normoxic environment to reduced pressure. Experimental data is discussed and some protocols for safe transition to reduced pressure are recommended.