Here at the surface of the Earth, in gravitational terms, we are at the bottom of a hole that is 4,000 miles deep. Everything that we want to put in geosynchronous orbit must be hoisted up out of that hole. The alternative—what we might call the judo approach, using our adversary's strength instead of wasting our own—is to build all the heaviest components of satellite power stations out of material that is already waiting there almost at the top of that 4,000 miles. The surface of the Moon is at a gravitational level about 95 percent of the way to geosynchronous orbit. More than that, because the Moon has no atmosphere and has such weak gravity, we could launch materials from the Moon by a far cheaper and more efficient method than we could ever use from the Earth, that is, by ground-based machinery. The main components of any satellite power station would be metals, glass, and possibly silicon. From the Apollo project, we know that the ordinary unselected soils from the surface of the Moon are typically 40 percent oxygen, 20 percent silicon and 20 to 30 percent metals by weight—just the elements we would need for constructing nearly all of the mass of a power satellite. The key points in the orbital manufacturing of satellite power stations would be, first, cashing in on the great success of the Apollo project, by using materials from the surface of the Moon. Second, bootstrapping; that is, launching from the Earth only a comparatively small amount of equipment and material, comparable in total mass to only one power satellite. That equipment would be in the form of a small mining and launching outpost on the Moon and a construction station in high orbit. Once a regular supply of lunar material was available at the orbital station, the station would build others of its kind as well as satellite power stations. In that way, without the escalation of a launch-vehicle fleet and the corresponding possible environmental impact on the upper atmosphere, the growth of the number of satellite power stations would be geometric in time, like the series 1, 2, 4, 8, 16, 32 and so on—rather than just linear, 1, 2, 3, 4, 5, 6. That would be the way to get big results in a short time. The third key point would be to depend only on the technology and the vehicles that we are sure of—power stations at the technology level of the present—that is, similar to the station referred to in the last talk, which is even now being put into operation in Oberhausen in West Germany—and freight rockets that can be derived quickly and at low cost from the Space Shuttle, using Shuttle main engines. The Shuttle in exactly its present form would also be an essential part of that program. Clearly, research on lower-mass powerplants and higher performance vehicles is worthwhile. But orbital manufacturing, we believe, makes the difference between encouraging that research and staking everything on its complete success. If satellite power is to be successful, at some point it must attract private capital, the sooner the better. Without satellite power, private capital will have to spend on nuclear and coal plants about $800 billion in the next 25 years. At this time there is no chance of attracting significant private capital into satellite power research, because the risks are too great.
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