to space power beaming projects. Sacrificed would be data on rectenna performance on Earth, but this is easy enough to obtain elsewhere. Also missing from this experiment would be the experience with mid-sized deployable structures that might be gained from a mid-range space to Earth demonstration. The structures used in a mid-sized satellite would probably bear little resemblance to those used for a large-scale power satellite, however, so experience with the smaller satellites would likely be little help with the large scale construction needed for larger satellites. This paper examines the possibilities for conducting an inexpensive Earth to space power beaming demonstration using existing facilities. Design trade-offs will be discussed for both ends of the link: on the ground, potential facilities will be examined for power, transmission frequency, aperture, and tracking capability; while in space issues of orbit selection, launch vehicle choice, and satellite design will be addressed. Possible objectives of such a mission will be discussed, and a brief look at costs and time schedules included. Recommendations will be made with respect to these issues, and areas which need further study will be pointed out. It should be emphasized that this paper does not pretend to present a complete, workable design. The exact form of an actual Earth to Space power beaming experiment of this type will depend on the specific scientific objectives to be fulfilled and on the budgetary constraints that the program must operate within. This paper merely points out the benefits of the approach and the issues that will need to be addressed to bring the concept into reality. Facilities There are two broad categories of facilities which would be appropriate as radiators for an Earth to space power beaming experiment: military and civil. The military systems of interest are the large radar systems used during the past 40 years as a part of ballistic missile early warning systems. European systems with similar intent exist, but are smaller and less powerful than their American counterparts and hence are not considered here. Little is known of the corresponding Russian systems, but from the sketchy information available from Jane's Defence Data it seems that they would be largely inappropriate for power beaming. The only serious Russian candidate for the type of mission considered in this paper was destroyed in 1992 as part of a US-FSU arms reduction pact. Relevant civil systems are radar systems used for astronomical observations and spacecraft tracking. Table 1 shows some of the vital statistics of the major US military and civilian radar systems. In a brief survey of the table, the facilities at Arecibo Observatory in Puerto Rico stand out from the rest. Its 305 meter dish provides more than 40 times the radiator area of the next largest system, its S-band radar uses a frequency five times higher than most of the military radars, and it is capable of continuous power beaming. It’s closest competitor, COBRA DANE, can generate with its pulses a power density only 17% of Arecibo's, with an average of 1%. In addition to a lower power density, COBRA DANE'S remote polar location, northward facing, and low elevation detract from its utility in a power beaming experiment. In contrast, Arecibo has a low-latitude location and points toward the sky, not the horizon.
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