New THERME Experiment Concept for Measuring Thermal Coating Aging

The French Space Agency has developed a simple, low-cost experiment, “THERME,” which aims to assess the aging of thermal coatings by measuring solar absorptivity. This experiment is now used on-board several low-Earth-orbit (LEO) Sun-synchronous satellites. The most significant in-orbit results for thermal control coatings (white paints, second surface mirrors, and Kapton) are summarized in this paper. To use THERME on-board geostationary Earth orbit (GEO) missions, the existing THERME concept had to be modified to allow typical rigid GEO thermal coatings such as optical solar reflectors to be carried. This new concept was developed based on the LEO THERME design and was made to be as nonspecific as possible, and so it may be carried on any industrial GEO satellite. The development and qualification of this new THERME concept, the so-called “THERME GEO” or “THERME rigid,” is presented in this paper. “THERME GEO” is currently being used on two telecom satellites. All the flight models were subject to therm...