seconds. Comparison of this streaming expansion model (w is not necessarily the thermal speed) with (4) shows that [[spi:math]] and z = ut, as it should be. As we shall see, the dense neutral cloud at early times would significantly influence the lifetimes of charged particles in the magnetosphere. For the second phase of the neutral chemical exhaust emission scenario, we must consider the fate of the rocket burns. Dr. Chul Park of NASA/Ames has worked out a likely scenario of the POTV burns (private communications from Dr. Chul Park), based on an earlier version of the SPS concept which involves fewer workers at GEO requiring 561 metric tons of ignition weight at LEO for the POTV [Piland, 1979]. The official baseline concept [DOE, 1979; NASA, 1978] specified the POTV ignition weight to be 890 metric tons at LEO. We have accordingly revised Dr. Park’s scenario for the official version of the POTV chemical exhaust emissions. The fates of the various POTV burns are shown in Figure 6. According to Park’s construction, a POTV mission requires five engine burns. They are named here for convenience Burns 1 through 5 where: Burn 1 is the acceleration burn at LEO using the first stage engines to deorbit from LEO, Burn 2 is the acceleration burn at GEO using the second stage engines to circularize at GEO, Burn 3 is the deceleration burn at GEO using the second stage engines to deorbit from GEO, Burn 4 is the deceleration burn at LEO using the second stage engines to circularize at LEO, and Burn 5 is the deceleration burn at LEO of the first stage vehicle using the first stage engines for circularization at LEO. In time sequence, Burn 5 occurs prior to Burn 3. The masses of fuel burned, the absolute velocities of effluents^ and the eventual fate of the effluents are listed in Figure 6. In the figure, the negative sign denotes the direction opposite to the earth’s rotation. The finite range in the velocities given are due to the fact that the vehicles change velocity during burns. The fates of the effluents are judged 11
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