I. INTRODUCTION The space segment of the satellite power system (SPS) is projected to operate at geosynchronous orbit (GEO) at an altitude of ~ 36,000 km [~ 6.6 earth radii (RE) from the center of the earth in the equatorial plane]. During the spacecraft construction phase, transportation and assembly activities will take place between low earth orbit (LEO) at ~ 400 km altitude and GEO. Thus, the operational activities of the SPS and a major segment of the constructional activities take place in the magnetosphere, which is a region of near-earth space where the ionized medium is controlled by magnetic and electric fields. These activities in space represent a loading upon the tenuous but spatialy vast magnetospheric environment. The magnitude of this loading, in the form of injections of matter and energy, can be qualitatively accentuated by comparison of the mass of the SPS spacecraft [~ (3-5) x 107 kg] at GEO with the largest spacecraft operated to date [Skylab, ~ 7 x 104 kg] at LEO. While Skylab did not seem to have any appreciable effects upon the magnetosphere, the key question, however, is whether the scaling-up of spacecraft mass by three orders of magnitude and the scaling-up of orbit altitude by two orders of magnitude would have appreciable magnetospheric effects. Further, if magnetospheric modifications were expected, what mitigation strategies would be required in system design? The primary goal of the assessment effort is to evolve an answer to the above key questions. This report represents our assessment in FY79 and FY80 of the magnetospheric effects of SPS based upon application of present knowledge and is written with a view toward recommendations for future studies and observations needed to verify the assessments. As such, we have focused our efforts to assess the entire range of magnetospheric effects which may con1
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