1. J.F. KEVILLE cal elements as low as -100°C. The primary radiator surfaces use second surface mirrors with solar absorptance values as low as 0.05. The solar absorptance of these radiator surfaces increases with time because of deposition of contaminants vaporized from other warmer parts of the satellite. This small but steady increase in absorbed solar energy causes the aforementioned warming trend. Although significant advances have been made in suppressing such contamination on recent satellites, present space radiator cooled satellites still must be expected to demonstrate such warming characteristics. Early in 1973, a program to forestall the effects of such warming on these satellite systems was undertaken by Aerojet ElectroSystems under contract to the Space and Missile System Organization of the United States Air Force Systems Command.