Effect of Simulated Lunar Dust on the Properties of Thermal Control Surfaces

摘要

NASA Johnson Space Center's lunar simulant JSC-1AF has been applied to a white thermal control paint and a second-surface mirror thermal control surfaces on aluminum or composite substrates in a simulated lunar environment. The temperature of these surfaces was monitored as they were heated with a solar simulator and cooled in a 30 K cold box. Thermal modeling was used to determine the absorptivity (α) and emissivity (ε) of the thermal control surfaces in both their clean and dusted states. Then, a known amount of power was applied to the samples while in the cold box and the steady-state temperatures measured. It was found that even a submonolayer of simulated lunar dust can significantly degrade the performance of both white paint and second-surface mirror type radiators under simulated lunar conditions. Contrary to earlier studies, dust was found to affect s as well as α. Dust lowered the emissivity by as much as 16% in the case of the white thermal control paint and raised it by as much as 11 % in the case of the second-surface mirror. The degradation of thermal control surface by dust as measured by α /ε rose monotonically regardless of the thermal control coating or substrate, and extrapolated to degradation by a factor 3 at full coverage by dust. Submonolayer coatings of dust were found to not significantly change the steady-state temperature at which a shadowed thermal control surface will radiate.