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The industrialization of near-earth space has already begun during the last few space shuttle flights and will continue at an ever-accelerating pace as the first United States space station is built in the next 8 yr. However, the economic return from near-earth space industry is limited by the high cost per kilogram of launching into orbit the structural elements needed to build the space stations and the raw materials that are to be made into products in them. This limiting factor can be overcome if the moon is used as a source of the material needed to build the space structures and as the source of the raw materials needed in the processing. First, O, Si, Mg, Fe, Ca, Al, and Ti are the major constituents (> 1% by weight) in lunar rocks, and can be obtained directly rom them by one of several proposed processes. Of these, O is needed as a rocket fuel, Si for making solar cells to generate space-station electricity, and light weight Mg, Al, and Ti to make structural elements for the space stations. Second, the rocket fuel per kilogram of payload needed to reach low earth orbit from the moon is 68% of that needed from the earth's surface, assuming that decelerating into earth orbit is achieved by a rocket maneuver. The amount of fuel is reduced to 15% if orbit is achieved by aero-braking. If the payload is launched from the moon by a "mass driver" and aero-braking is used, the cost in the rocket fuel needed to reach low earth orbit is reduced to nearly zero.
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