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Cooling Properties of the Shuttle Advanced Crew Escape Spacesuit: Results of an Environmental Chamber ExperimentThe shuttle crew wears the Advanced Crew Escape Spacesuit (ACES) to protect themselves from cabin decompression and to support bail out during landing. ACES is cooled by a liquid-cooled garment (LCG) that interfaces to a heat exchanger that dumps heat into the cabin. The ACES outer layer is made of Gore-Tex(Registered TradeMark), permitting water vapor to escape while containing oxygen. The crew can only lose heat via insensible water losses and the LCG. Under nominal landing operations, the average cabin temperature rarely exceeds 75 F, which is adequate for the ACES to function. Problem A rescue shuttle will need to return 11 crew members if the previous mission suffers a thermal protection system failure, preventing it from returning safely to Earth. Initial analysis revealed that 11 crew members in the shuttle will increase cabin temperature at wheel stop above 80 F, which decreases the ACES ability to keep crew members cool. Air flow in the middeck of the shuttle is inhomogeneous and some ACES may experience much higher temperatures that could cause excessive thermal stress to crew members. Methods A ground study was conducted to measure the cooling efficiency of the ACES at 75 F, 85 F, and 95 F at 50% relative humidity. Test subjects representing 5, 50, and 95 percentile body habitus of the astronaut corps performed hand ergometry keeping their metabolic rate at 400, 600, and 800 BTU/hr for one hour. Core temperature was measured by rectal probe and skin, while inside and outside the suit. Environmental chamber wall and cooling unit inlet and outlet temperatures were measured using high-resolution thermistors ( 0.2 C). Conclusions Under these test conditions, the ACES was able to protect the core temperature of all test subjects, however thermal stress due to high insensible losses and skin temperature and skin heat flow may impact crew performance. Further research should be performed to understand the impact on cognitive performance.
Document ID
20080046861
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Hamilton, Douglas
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Gillis, David
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Bue, Grant
(Boeing Aerospace Co. Houston, TX, United States)
Son, Chan
Norcross, Jason
Kuznetz, Larry
Chapman, Kirt
Chhipwadia, Ketan
(NASA Johnson Space Center Houston, TX, United States)
McBride, Tim
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2008
Subject Category
Man/System Technology And Life Support
Meeting Information
Meeting: 80th Annual Scientific Meeting of the Aerospace Medical Association (ASMA)
Location: Los Angeles, CA
Country: United States
Start Date: May 3, 2009
End Date: May 7, 2009
Distribution Limits
Public
Copyright
Other

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