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Proceedings Paper

Atomic oxygen erosion of a graphite coating on a TQCM onboard the Return Flux Experiment (REFLEX)
Author(s): Steve M. Benner; Charles C. Lorentson; Philip T. C. Chen; Shaun R. Thomson
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Paper Abstract

A TQCM coated with graphite was flown aboard a Spartan carrier in January 1996. During a flight of about 46 hours at an altitude of 305 km, the graphite reacted with the atomic oxygen (AO) in the environment and was eroded away. The 15-MHz TQCM's frequency dropped from 6800 to 4000 Hz in about 15 hours of exposure and was shown to be a strong function of the TQCM's orientation to the ram direction. The erosion rates for four different ram angels was measured and found to be both consistent and repeatable. The average graphite volume loss for the 61 degree and -62 degree ram angles was calculated to be about 2 X E-08 cm3/hr and for the 18 degrees and 19 degrees angles to be about 8.5 X E-08 cm3/hr, which is slightly less than previous flight data. The erosion data was then correlated with AO density numbers for the particular times and positions of the spacecraft in orbit. From this analysis, an equation was derived that shoed the carbon volume loss as a function of both atomic oxygen density and ram angle. For example, 1.59 E-07 cm3/hr would be the calculated carbon volume loss for a ram angle of 0- degrees and an AO fluence of 3.52 E+17 atoms/hr. The results of this data and analysis may lead to the development of a sensor capable of monitoring the AO fluence on a spacecraft.

Paper Details

Date Published: 27 October 1998
PDF: 10 pages
Proc. SPIE 3427, Optical Systems Contamination and Degradation, (27 October 1998); doi: 10.1117/12.328489
Show Author Affiliations
Steve M. Benner, NASA Goddard Space Flight Ctr. (United States)
Charles C. Lorentson, NASA Goddard Space Flight Ctr. (United States)
Philip T. C. Chen, NASA Goddard Space Flight Ctr. (United States)
Shaun R. Thomson, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 3427:
Optical Systems Contamination and Degradation
Philip T. C. Chen; William E. McClintock; Gary J. Rottman, Editor(s)

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