costs at the earth would be $450 and $900 on the basis of electric energy costs of 5 cents and 10 cents per kilowatt-hour, respectively. One of the potential objections to the electric propelled vehicle is the relatively long calendar transit times. However, the transit times can be greatly reduced by placing more transmitters on the equator. Some of- these could be relatively low in power and cost and would be used only for satellites in relatively low altitude orbits. In the context of adding low-power, ground-based transmitters there is the nucleus of a universal ground-to-space power system. These additional lower-powered ground stations could supply power not only to the interorbital vehicles in low-earth orbit but also could send energy to manufacturing satellites rotating in equatorial orbit. Eventually, in an expanding space economy, the number of both ground stations and satellites would increase to the point where the duty cycles of both would approach 100%. Operating in a high duty cycle mode such a system could be very cost competitive with other means of supplying large amounts of power to low-earth satellites. ACKNOWLEDGMENTS The support of NASA and the Raytheon Company for the technology advances that have been discussed is acknowledged. All illustrations are reprints with permission of the Raytheon Company.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==