Ultraviolet Irradiation Effects on Candidate Spacelab Thermal Control Coatings

The advent of Spacelab has made it necessary to review those materials that are acceptable for passive thermal control. This paper describes the ultraviolet vacuum simulation tests performed on several candidate Spacelab thermal control coatings. The in-situ degradation curves of solar absorptance as well as in-air degradation values of normal emittance and solar absorptance are presented. Also included is a description of the ESTEC combined irradiation chamber. This facility is equipped for simultaneous particle (electron and proton) and ultraviolet irradiation. An integrating sphere inside the chamber enables in-situ measurements of the spectral and total solar absorptance of a test specimen. The test results of several candidate materials, including a white paint and a silica fabric, are discussed.