thereafter with two satellites launched each year in columns 4 and 5. The first satellite includes not only transportation and rectenna, but also the orbital staging and construction bases, plus the construction of the cargo orbital vehicles. It should be noted that because the gallium arsenide system has both construction bases as total mass estimates at this time, (see Table 5) the mass of those components is indicated under miscellaneous and organics heading. L. Operations SPS operations include those activities required to build SPS's and then to operate and maintain them. This requires a wide variety of activities as illustrated by figure 33. Because studies of most of these activities are not yet complete, this section will briefly outline the overall SPS operation as it appears at this time. 1. Construction Operations Construction of an SPS starts with two supporting operations. First the necessary raw materials are mined and manufactured into launch-ready components and propellants. A significant mass production capability will need to be developed to produce the high number of components needed per satellite (e.g., about 10^ solar cells, 10$ klystrons, 10^ dipoles). Similarly, requirements for large amounts of propellants (oxygen, hydrogen, argon) demand expanded processing capabilities. The other supporting function involves ground transportation of raw materials, fabricated components, and assemblies to the launch site. Also, about 10$ MT of hydrocarbon propellants are used per year. Among the possibilities for propellants under investigation are processing coal at mines and using a gas transmission system, transporting coal to the launch site, using rectenna-supplied electricity to electrolyze water, and others. At the launch site, principal activities involve receiving, storing, and processing of material and propellants; launching vehicles; and refurbishing and checking out returning vehicles.
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