Degradation of Apollo 11 Deployed Instruments because of Lunar Module Ascent Effects

Three similar horizontal solar cells were deployed by the Apollo 11 astronauts to measure whether the lunar module ascent caused degradation of their surface properties and resultant thermal control. The outputs of the cells at lunar module ascent decreased approximately 18%, 7%, and 0%. The average absorptivity thus decreased approximately 8%, while the average emissivity decreased approximately 12%, resulting in overheating. The results are discussed and several possible causes are suggested. Subsequently, the surface absorptivity and emissivity of each cell changed less than 1%–2% during the following month. Lunar module ascent effects for the closely deployed Apollo 11 instruments were therefore much more important than the long-term exposure to the lunar environment. The relevance of these findings to future deployment of lunar instruments is discussed.