V CHEMICAL ENGINE EXHAUST IN MAGNETOSPHERE The importance of assessing the effects of POTV chemical engine exhaust in the magnetosphere was not immediately realized at the initial phases of the magnetospheric effects assessment effort. However, in the course of assessing effects on modification of ring-current and auroral processes, we came to realize that the quantity of neutral exhaust and the location of its injection are so critical to ring current dynamics that assessment of auroral modification would be quite meaningless unless the effects of neutrals were included. In the SPS atmospheric effects meeting in LaJolla 1979, Dr. C. Park of NASA/Ames constructed the probable POTV chemical exhaust emission scenario. The location and amount of chemical engine burn 2 (Figure 6), which is gravitationally trapped in essentially collisionless orbits, would profoundly affect the natural ring current even if we do not consider accumulative effects over a number of POTV flights. In FY80, we started to examine the effects of POTV neutral exhaust in depth. It was discovered that the amount of chemical exhaust estimated by Park was low by a factor of about 1.8 because the POTV payload according to the DOE SPS Concept Report (U.S. DOE, 1978) is much higher than that assumed in an earlier unofficial SPS concept description (Piland, 1979), from which Park’s estimates were made. In this report, Park’s emission scenario is adopted for the increased emission of the SPS Concept Report. A. Reduction of Ring Current Lifetime The main effect of the neutral exhaust cloud is that it acts as an artificial source that can charge-exchange with ring-current ions, thereby reduc63
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