Off-Nominal Planning for the Cryogenic Thermal Vacuum/ Thermal Balance Test of the James Webb Space Telescope Optical Telescope Element/Integrated Science
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Abstract
The cryogenic thermal vacuum/thermal balance test of the James Webb Space Telescope (JWST) combined Optical Telescope Element (OTE)/Integrated Science Instrument Module (ISIM), known as the OTIS, at the Johnson Space Center (JSC) Chamber A in 2017 was likely the most complex test ever performed by NASA for an unmanned mission. The test of the combined flight Optical Telescope and ISIM elements was prefaced by years of modifications to chamber facilities, and included three extensive precursor tests of non-flight and flight hardware to establish safe and optimal test operational procedures. One critical part of the test preparation was planning for off-nominal events that could arise, including appropriate responses. In some cases, assurance of personnel and payload safety required modification of original test hardware and procedures which had to be validated before the final test could begin. This planning proved especially prescient for the OTIS test, as Hurricane Harvey struck the Houston area during the test in August 2017, and consequences for the precious payload could have been severe. This paper describes the extent of the thermal off-nominal planning undertaken for the OTIS test, including including safing for hurricanes, and some real-life effects of Hurricane Harvey on the test conduct. Documentation of the consequences and mitigations for these events are discussed. The importance of off-nominal planning for future thermal vacuum/thermal balance tests is illustrated.
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Brian Comber, Genesis Engineering Solutions
Kan Yang, NASA
Paul Cleveland, Engineering Solutions International
Wes Ousley, Genesis Engineering Solutions
ICES108: Thermal Control of Cryogenic Instruments and Optical Systems
The 48th International Conference on Environmental Systems was held in Albuquerque, New Mexico, USA on 08 July 2018 through 12 July 2018.