simply by comparing the absolute velocities with the escape velocities, which are 10.76 km/sec at LEO and 4.34 km/sec at GEO. Thus, effluents from Burns 3, 4 and 5 will escape. Effluents from Burn 1 will likely fall back to earth, although, being released at LEO, it will not be in the area of concern to this study. As indicated in the figure, the effluents of Burn 2 are trapped in an earth-bound orbit at the rate of 145 metric tons per POTV mission. The center of gravity of the effluent mass has a perigee of 14,400 km above sea level, an apogee of 35,800 km above sea level (GEO), and a period of 18 hours. But the effluents (~ 1031 molecules) are spread over a wide range: some particles have a perigee as high as 30,000 km while others have only 3000 km. Since the typical densities of naturally occurring charged and neutral particles in this region are [[spi:math]] 103 cm-3, the collisional lifetimes of these injected particles are likely to be months; thus, giving rise to the possibility of accumulating a "torus” or "belt" of neutrals in the region (3-6) RE from successive POTV missions. It appears that the effects of this second phase of neutral emission scenario will be of long time scale rather than transient. We have attempted to collect and summarize the available information on emission parameters of argon ion engines and of LO2/LH2 chemical engines in the magnetosphere for the SPS program. As we can see, the information available is not sufficient for a complete environmental assessment although it does allow limits of magnetospheric modifications to be roughly defined. The evolution of each exhaust emission outside of the immediate vicinity of the relevant spacecraft represents the effects of magnetospheric modification. These will be treated separately in the rest of this report. 1 2
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