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Effects of Heating on Teflon(Registered Trademark) FEP Thermal Control Material from the Hubble Space TelescopeMetallized Teflon(Registered Trademark) FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) is degrading in the space environment. Teflon(Registered Trademark) FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A Failure Review Board (FRB) was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid state nuclear magnetic resonance (NMR) analyses of FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200 C, than the SM1 material, estimated at 50 C. An investigation on the effects of heating pristine and FEP exposed on HST was therefore conducted. Samples of pristine. SM1, and SM2 FEP were heated to 200 C and evaluated for changes in density and morphology. Elevated temperature exposure was found to have a major impact on the density of the retrieved materials. Characterization of polymer morphology of as-received and heated FEP samples by NMR provided results that were consistent with the density results. These findings have provided insight to the damage mechanisms of FEP in the space environment.
Document ID
19990049235
Document Type
Reprint (Version printed in journal)
Authors
deGroh, Kim (NASA Glenn Research Center Cleveland, OH United States)
Gaier, James R. (NASA Glenn Research Center Cleveland, OH United States)
Hall, Rachelle L. (Ohio Aerospace Inst. Cleveland, OH United States)
Norris, Mary Jo (Cleveland State Univ. Cleveland, OH United States)
Espe, Matthew P. (Akron Univ. Akron, OH United States)
Cato, Daveen R. (Akron Univ. Akron, OH United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1999
Subject Category
Chemistry and Materials (General)
Report/Patent Number
NAs 1.15:209085
NASA/TM-1999-209085
E-11668
Funding Number(s)
PROJECT: RTOP 632-1A-1E
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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