Thermal control of the large space telescope /LST/

Author(s):  
R. CUMMINGS
1975 ◽  
Author(s):  
S. OKEN ◽  
D. SKOUMAL ◽  
J. STRAAYER ◽  
C. LOY
Keyword(s):  

2006 ◽  
Vol 929 ◽  
Author(s):  
Kim K. de Groh ◽  
Joyce A. Dever ◽  
Aaron Snyder ◽  
Sharon Kaminski ◽  
Catherine E. McCarthy ◽  
...  

ABSTRACTDuring the fourth servicing mission of the Hubble Space Telescope (HST), the second set of solar arrays (SA-II) was replaced with a third set and the SA-II was brought back to Earth. A section of the retrieved SA-II solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was provided to NASA Glenn Research Center for environmental durability analyses of the top layer of silver-Teflon fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Therefore, the objective of this research was to characterize the degradation of retrieved HST SADA Ag-FEP with particular emphasis on solar radiation effects. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface of the SADA was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 ± 0.032) and the anti-solar facing surface (0.208 ± 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect.


1973 ◽  
Vol 95 (4) ◽  
pp. 1039-1047 ◽  
Author(s):  
H. Fine ◽  
J. Quadrini ◽  
S. Ollendorf

The Orbiting Astronomical Observatory (OAO)-C was successfully launched into 400-nautical mile circular orbit on August 21, 1972. For this spacecraft, a unique sensitivity approach to the thermal design was developed which resulted in a predictal design—the merits of which should be considered for application on future spacecra. The OAO-C is also serving as a test bed for the evaluation of thermal control hardware. To provide flight data for space program applications, experiments for a new coating and four different heat pipe designs are on this spacecraft. The data derived from OAO-C will be extremely valuable for such future programs as the Large Space Telescope (LST) and the Earth Observation Satellite (EOS). This paper will describe the detailed of the sensitivity design approach and thermal control hardware. For all aspects discussed, a comparison of pertinent analysis, ground test data, and flight data [1] will be given.


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