EFFECTIVENESS OF RADIATION SHIELDS FOR THERMAL CONTROL OF VEHICLES ON THE SUNLIT SIDE OF THE MOON

摘要

Analyses are presented for studying the problems of thermal control associated with vehicles on the lunar surface during the daytime and evaluating the effectiveness of solar and lunar radiation shields in minimizing these problems. Included in the analyses are inputs of direct solar radiation, solar radiation reflected from the lunar surface, radiation emitted from the lunar surface, internally generated power, and, for a shielded vehicle, radiation reflected and emitted from the shields. An additional analysis is presented for studying the effect of conduction in the skin upon the temperature variation around a vehicle illuminated from the side.nTemperatures of unshielded vehicles were found to be a strong function of the ratio of solar absorptance to emittance (αs/ε) of their surfaces and might be excessively high during daytime. Even with coatings of very lowαs/ε, the vehicle temperatures could be undesirably high as a result of absorption of radiation emitted from the hot lunar surface. When an unshielded vehicle is subjected to solar illumination from the side, as may be encountered at dawn, dusk, or at the poles, large temperature differences and gradients are found to occur from the sunlit to the shaded side of the vehicle.nResults of this study indicate that solar and lunar radiation shields can eliminate many of the thermal problems apparent with unshielded vehicles on the lunar surface. Solar shields may reduce the amount of incident solar radiation so greatly that the temperatures on the vehicle will become independent of the vehicle's surface properties. Lunar radiation shields may be used to isolate, effectively, the vehicle from radiation emitted from the lunar surface. With a combination of solar and lunar shields, the surface temperatures of a vehicle can be reduced to a desirable level.