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Gas flow analysis during thermal vacuum test of a spacecraftThe self-contamination of the IMP-H spacecraft, while it was undergoing thermal and solar vacuum tests, has been investigated in conjunction with the outgassing evaluation and detection of molecular flow anomalies occurring in the test chamber. The pressures indicated by two tubulated ionization gauges were used to calculate flow kinetics in the vacuum chamber. The fluxes of emitted molecules and chamber wall reflected molecules were monitored during the entire test. Representative equations and graphs are presented. Test results indicate that from 3 to 9 of every 100 emitted molecules returned to the spacecraft surface; that self-contamination by noncondensable gases was more severe than that by condensable gases; and that outgassing of the spacecraft was approximately 1.18 x 0.01 g/s after 10 hours and 1.18 x 0.001 after 90 hours of vacuum exposure. Testing deficiencies have been identified, and the type and location of instruments required to measure the outgassing, the degree of contamination, and return flow are discussed.
Document ID
19740006849
Acquisition Source
Legacy CDMS
Document Type
Other - NASA Technical Note (TN)
Authors
Scialdone, J. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1974
Subject Category
Facilities, Research, And Support
Report/Patent Number
NASA-TN-D-7492
G-7346
Accession Number
74N14962
Funding Number(s)
PROJECT: RTOP 697-06-01-84
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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