VII. SUMMARY OF MAGNETOSPHERIC EFFECTS Exhaust emissions from propulsion and stationkeeping activities of the SPS spacecraft induce substantial modifications of magnetospheric processes on both the local and the global scale. This is primarily because of the relatively large mass and energy contents of these emissions when compared with the total mass and energy contents of the inner magnetosphere. The sources of these emissions are: (a) the argon plasma jet from the solar electric propulsion modules of the cargo orbit transfer vehicle (COTV), and (b) the H2O neutral exhaust from LO2/LH2 main engines of the personnel orbit transfer vehicles (POTV). Assessment of the SPS scenario, based on presently-known physical mechanisms operative in plasma and neutral injections in the magnetosphere, indicates that the major part of the ion emission and a substantial part of the neutral emissions are likely to be deposited inside the magnetosphere. Injection of argon ions of 3.5 keV energy causes magnetospheric modifications in several ways. The energy released is sufficient to cause turbulent response in the magnetospheric plasma. As this free energy evolves, the magnetospheric composition is modified not only by the presence of argon ions but also by the heating. This physical evolution of injected energy and mass causes an increase in the intensity of radiation belt relativistic electrons which may require mitigation on the part of systems design in space equipment and human activity. At low earth orbit (LEO), a substantial fraction of the energetic argon may escape magnetic confinement and impact the atmosphere in the form of the intense beam. The optical emissions stimulated by such a beam may be about an order of magnitude more intense than the aurora at near UV wavelengths. The possible interference with space-borne optical sensors 75
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