Thermal control coatings performance at near geosynchronous altitude

Abstract

Flight measurements on 16 spacecraft thermal control coating materials over 10 yr at geosynchronous altitude are reported. Fused-silica second-surface mirrors and polished metals are essentially stable in space; observed increases in solar absorptance <0.002/yr are ascribed to contamination. Metalized Teflon® FEP and aluminized Kapton® darken over a long period of time. Two types of conductive mirror coatings darken measurably. The backing material on Astroquartz fabrics influenced their darkening. The time dependence of the darkening of these samples is well described by physical models of the degradation processes. 3M 401C10 black paint and Grafoil samples lighten over a long time period. NASA/GSFC NS43G conductive yellow paint darkens over a long time period.