AN ASSESSMENT OF HABITAT PRESSURE, OXYGEN FRACTION, AND EVA SUIT DESIGN FOR SPACE OPERATIONS

At high cabin pressure [e.g. 1013 hPa (14.7 psi) 21% O2] there are ser ious issues relative to specification of suit pressure and the need fo r prebreathing. A high pressure suit will be costly but use of the exi sting, flexible suit requires up to 6 h of prebreathing. Or one could use a cabin pressure of 700 hPa (10.2 psi) prior to extravehicular act ivity (EVA) in order to use the existing suit with only 1 h of prebrea thing. If these normal cabin pressures and O2 levels are utilized. exi sting physiological and medical databases apply, providing a known bas is for evaluating effects of long duration space missions. If a 345 hP a (5 psi), 70-100% O2 atmosphere is adopted the existing suit can be u sed with no prebreathing required. However, there is no reference data base on physiological effects under the conditions of lower pressure a nd higher O2 concentration. This paper considers the major issues invo lved in defining habitat pressure, O2 fraction, and EVA suit design fo r operations in space. A preliminary model for evaluating habitat/suit pressure and O2% strategies is presented.