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Degradation of FEP thermal control materials returned from the Hubble Space TelescopeAfter an initial 3.6 years of space flight, the Hubble Space Telescope was serviced through a joint effort with the NASA and the European Space Agency. Multi-layer insulation (MLI) was retrieved from the electronics boxes of the two magnetic sensing systems (MSS), also called the magnetometers, and from the returned solar array (SA-I) drive arm assembly. The top layer of each MLI assembly is fluorinated ethylene propylene (FEP, a type of Teflon). Dramatic changes in material properties were observed when comparing areas of high solar fluence to areas of low solar fluence. Cross sectional analysis shows atomic oxygen (AO) erosion values up to 25.4 mu m (1 mil). Greater occurrences of through-thickness cracking and surface microcracking were observed in areas of high solar exposure. Atomic force microscopy (AFM) showed increases in surface microhardness measurements with increasing solar exposure. Decreases in FEP tensile strength and elongation were measured when compared to non-flight material. Erosion yield and tensile results are compared with FEP data from the Long Duration Exposure Facility. AO erosion yield data, solar fluence values, contamination, micrometeoroid or debris impact sites, and optical properties are presented.
Document ID
Document Type
Technical Memorandum (TM)
Zuby, Thomas M.
(Unisys Corp. Lanham, MD., United States)
Degroh, Kim K.
(NASA Lewis Research Center Cleveland, OH., United States)
Smith, Daniela C.
(Cleveland State Univ. OH., United States)
Date Acquired
September 6, 2013
Publication Date
December 1, 1995
Subject Category
Chemistry And Materials (General)
Report/Patent Number
NAS 1.15:104627
Distribution Limits
Work of the US Gov. Public Use Permitted.

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NameType 19960012199.pdf STI