3) Much reduced Earth launch vehicle requirements due to lower payload requirements. This results in reduced propellant consumption and atmospheric pollution. Launch vehicle size and flight schedule can also be reduced greatly. 4) Economic and environmental gains accruing from these reduced Earth activities, assuming that equivalent revenue-generating satellites can be produced with lunar resources. The SPS design baseline used for the lunar resources utilization study was a 10 gW satellite assembled in space entirely of Earth-manufactured components (reference #3). Minor material substitution and design modifications were imposed to increase the amount of lunar material utilization to approximately 90% of total SPS mass. With this revised SPS design, the study concluded that LRU was economically competitive with an SPS constructed totally of Earth materials. It is anticipated that an SPS configured specifically to utilize lunar resources will have an LRU mass fraction much greater than 90%, and may therefore represent a commercially attractive investment option. F. THE LUNAR SURFACE — COMPOSITION AND CHARACTERISTICS The surface of the Moon is characterized by large dark areas, designated Maria, and light colored areas generally a kilometer higher in elevation than the Maria. These highland areas are severely cratered as a result of meteorite impacts. Chemical analyses of surface and slightly subsurface soil and rock samples have been performed on material collected by six Apollo and two Luna spacecraft (reference #4). The composition of the lunar crust, insofar as the sampling to date permits, is somewhat similar to that of Earth's in that oxygen and silicon comprise the major elements, and at least eight of the ten most abundant elements in the Earth's crust are also among the most prevalent in the lunar crust. Of the ten most abundant elements in the Earth's crust (see Table I)
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