Effectiveness of the Space Shuttle anti-exposure system in a cold water environment

The purpose of this study was to evaluate the National Aeronautics and Space Administration (NASA) Space Shuttle Launch Entry Suit (LES) and raft for 24 h of protection against cold water immersion. Two configurations, the LES and the LES with raft (Navy LRU-18/U with NASA spray shield) were evaluated for anti-exposure protection. Conditions were selected to simulate worst case water and air temperatures along projected Space Shuttle ground tracks; i.e., water temperatures = 4.4 degrees C (40 degrees F), air temperature = 5.6 degrees C (42 degrees F), 1 foot waves (chop), and constant spray. Four males, 31-44 years of age, and one 32-year-old female, were studied once in each configuration. Trials with and without a raft were scheduled for up to 24 and 6 h, respectively. Mean LES trial durations were 150 +/- 9 min and final rectal temperature (Tre, f) = 36.5 +/- 0.3 degrees C. Mean LES with raft (LES/r) trial durations were 398 +/- 126 min and final rectal temperature (Tre, f) = 35.6 +/- 0.4 degrees C. LES and LES/r trials were terminated for reaching Tre = 35.0 degrees C or subject-requested termination due to discomfort. The longest LES and LES/r trials were terminated due to subject discomfort. Although not achieving the desired durations, the LES and LES/r did prove capable of protecting individuals, respectively, for up to 3 and 13.5 h. Since the longest LES and LES/r runs were terminated due to subjective tolerance and not physical incapacitation, actual survival times greater than 3 and 13.5 h, respectively, could be expected for individuals in these ensembles.