life as well as for the non-isothermal nature of the radiating surface and redundancy. The rejection temperature given in Table III is a log mean effective rejection temperature. The fuel cell radiator, operating during the lunar night, was sized for a 20 K sink temperature. However, both the drying and liquefaction subsystem radiators operate during the lunar day, and, consequently, must reject heat to a signfiicantly higher sink temperature, in the order of 330 K. Since both of these subsystems are characterized by low effective rejection temperatures in relation to the sink temperature, it was desirable to make the sink temperature on the lunar surface as low as possible so as to reduce the radiator area and, therefore, the radiator mass. In order to reduce the lunar sink temperature, the radiator panels were oriented vertically with an aluminized plastic sheet, spread over as a cover over the lunar soil in the area immediately surrounding the radiator. The vertical orientation of the panels ensures that the radiator sees no direct solar energy, while the cover-sheet, having a lower solar absorptivity and thermal emissivity than the lunar soil, reduces the effect of reflected solar and thermal energy from the lunar surface. The configuration reduces the daytime equivalent sink temperature on the lunar surface from 330 K to approximately 220 K [7],
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