A Theoretical Method for Selecting Space Craft and Space Suit Atmospheres,
DUKE UNIV MEDICAL CENTER DURHAM N C F G HALL LAB FOR ENVIRONMENTAL RESEARCH
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A theoretical method for selecting space craft and space suit atmospheres is described. The method assumes that gas bubbles cause decompression sickness and that the risk increases when a critical bubble volume is exceeded. The method is consistent with empirical decompression exposures for humans under conditions of nitrogen equilibrium between the lungs and tissues. Space station atmospheres are selected so that flight crews may decompress immediately from sealevel to station pressure without preoxygenation. Bubbles form as a result of this decompression but are less than the critical volume. The bubbles are absorbed during an equilibrium period after which immediate transition to suit pressure is possible. Exercise after decompression and incomplete nitrogen equilibrium are shown to increase bubble size, and these factors limit the usefulness of one previously tested stage decompression procedure for the Shuttle. The method might be helpful for evaluating decompression procedures before testing.
- Life Support Systems