CONTAMINATION EFFECTS ON THE GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITE INSTRUMENT THERMAL CONTROL-SYSTEM

The instrument thermal control system of the Geostationary Operational Environmental Satellite may have been affected by specific contaminat ion problems that arose because of the unique conditions and requireme nts of the spacecraft mission. This paper addresses some specific cont amination effects from the coatings used in the instrument cavities, C ontamination control actions that were implemented during ground proce ssing to ensure limited impact on the on-orbit temperature control are described, The selection of thermal coatings is an integral part of t he overall spacecraft design. Molecular contamination accretion on the rmal coatings may alter the design properties of the surface coatings, In an effort to quantify the molecular contamination effects from mat erial outgassing, an assessment was conducted to address the concerns inside the instrument cavities. The study results prompted an extensiv e prelaunch vacuum bakeout effort and an on-orbit solar radiation avoi dance exercise, In addition, the thermal performance of the instrument radiant coolers could have been detrimentally affected by scattered s olar radiation from particulate contamination, To mitigate the impact of the particulate contamination the radiant cooler surfaces were clea ned to an established criteria prior to launch.