0191-9067/85 $3.00 + .00 Copyright ® 1985 SUN SAT Energy Council A Method for Comparison of Technologies for Orbital Transfer CARL ROSENE Rice University P.O. Box 1892 Houston, Texas 77251 Abstract — The success of the U.S. Space Shuttle, the increasing requirements for LEO to GEO and the new U.S. Space Station have placed attention on reusable Orbital Transfer Vehicles for LEO to GEO transfer. The current work develops the formulae necessary to compare different technologies that might be used in such a system. INTRODUCTION The United States’ space shuttle has proven the workability and usefulness of reuseable space vehicles. The reuseable shuttle provides transportation between ground and Low Earth Orbit (LEO). Yet, most of its payloads are destined not for LEO but rather for Geosynchronous Earth Orbit (GEO). There is no reuseable system to provide the transportation between LEO and GEO. Instead, each payload must include a throw-away boost vehicle to provide the orbit transfer. The burgeoning market for communication satellites, their increasing size (many planned satellites are already too big for existing systems), the new U.S. space station and the heralding of the end of throw-away satellites have focused attention on the problem of orbit transfer, and reuseable vehicles to provide the transfer. Many studies have been done comparing different technologies to be used in such a vehicle. These studies, however, consider only very narrow definitions of performance. Although these narrow definitions of performance allow a rigor that a broader analysis may prevent, they fail to show what performance areas are likely to prove to be the most critical in terms of the overall vehicle. This paper attempts to develop a broad overall look that may be used to show what areas of performance are likely to prove most critical for the economic viability of the system. This paper develops the techniques necessary to compare and evaluate any proposed orbital transfer system. More specifically, it provides the formula necessary to find the break-even price for an orbital transfer with a given system. The factors considered include capital costs of the vehicle, recurring maintenance, and the efficiency and configuration of the vehicle in terms of the technologies used. This paper does not attempt to make a conclusive comparison of the different technologies. Because of the nature of the formula derived it is not possible to make these comparisons without a detailed engineering analysis that is beyond the scope of this paper. However, some of the propulsive systems are looked at in a hypothetical case so that the results of the formula may be seen. TECHNIQUES Any proposed space vehicle can be considered to be made up of subsystems that
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