equipment is lower than that for the ceramics. Potential corrosion problems can be easily overcome by standard techniques of boiler feedwater treatment and the addition of small amounts of corrosion inhibiting chemicals. One such chemical, hydrazine, will be available in quantity due to its use in rocketry. Radiator Design A list of desired features is shown in Table I and is discussed below. Low Imported Weight The cost of payload launch from Earth is the overwhelming cost factor in establishing and maintaining a lunar base. Thus it is the weight imported to the moon that is crucial. Minimizing this weight can be done by use of exotic materials and inherently low weight designs or it can be done by using lunar materials. The plant for processing the lunar materials must be imported as must some other lightweight but sophisticated materials. The design should also be optimized to minimize the weight of the imported materials, not the overall weight. This can be done by simplification and avoidance of complicated equipment which needs to be imported. Use of lightweight imported materials such as radiation shields can reduce the weight of the radiator and working fluid and result in a reduction of imported mass. Unaffected by the Day-Night Cycle The significant swing in temperature on the lunar surface between day and night means that it is much easier to radiate heat at night than during the day. A system designed to handle the peak noon temperatures may be very oversized at night. This overcapacity may require reduction of the radiating area by shutdown of sections. Such shutdown and start-up is to be avoided if at all possible because it will be a constant source of problems in thermal stresses, sticking of moving parts etc. Start-up and shutdown of cooling equipment on Earth such as cooling towers and air cooled condensers is avoided by a variety of means for this very reason. Fortunately, on the moon it is possible to obtain the benefits of nighttime operation during the day if the radiator can be shielded from solar radiation as well as radiation from the lunar surface. This will give stable day and night operation as the environment of the radiator is not significantly changing, and give improved efficiencies. Optimized Heat Rejection It is desirable to avoid oversizing the radiator to handle peak loads which cause large swings in radiator temperature. It is also desirable to avoid unnecessary degradation of heat sources, so several temperatures of heat rejection may be desirable to minimize radiator area. Therefore it is desirable to match heat load to radiator performance as much as possible and be able to transfer heat to lower levels when heat rejection drops. The power plant is the major source of heat and electricity for the base and so must
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