Impact of lunar dust on radiator design for Moon bases and rovers

The change of thermal-optical properties caused by lunar dust on optical instruments, surface coatings, seals and spacesuit garments has been the subject of numerous theoretical and experimental studies over the past decades. Surface-craft, such as rovers or astronauts in spacesuits, stir up dust due to their own movement. Dust particles also move naturally along electrostatic gradients, for example between sunlit areas and those cast in shadow, or between a spacecraft, surface-craft or base structure and the lunar soil. In light of these findings, the degradation of thermal control surfaces due to dust contamination must be accounted for in the design not only of mobile systems, but for static objects on the Moon as well. In this work we model the impact of dust on thermal control surfaces, chiefly radiators. A discretized spherical body was used to evaluate different angles towards the lunar surface. A static as well as a transient model was used to account for long-term static as well as short-term dynamic influences. The time-dependent incident thermal radiation received from the Sun, Moon albedo and Moon infrared are accounted for in the model. Also the impact of elevated levels of infrared radiation in the vicinity of a lunar boulder was included. Radiators covered at 50% with lunar regolith are mostly affected in the solar radiation and less in the infrared part of the wavelength spectra. Thus, dusty radiators are increasingly sensitive to incoming solar radiation. The impact of lunar dust decreases with increasing lunar latitude and increasing view factor to the lunar surface. The results indicate that it is beneficial to either have adjustable surface coatings or steerable radiators. Another option would be sur-face pointing radiators at higher latitudes or close to the lunar terminator. The proposed de-sign options are complementary to dust mitigation techniques. An efficient radiator design should account for dust, local surface features and the time and latitude dependent Sun elevation angle.