1. 0
2. The analysis considers the effects of several parameter variations on the pressures at the target. The backscattered return flux has been computed for a range of ambient and emitted temperatures and ambient densities, and the equivalent pressure is determined from the return flux. The effects of varying the boom length and the radius of the wake shield have also been investigated. The results of the analysis are shown in Figs. 3-6. Figure 3 shows computed pressures at the shield as a function of emitted temperature for the two gases examined. It can be seen that the pressure at the target depends strongly on the emitted gas; the pressure is several orders of magnitude less for I^O emissions than for ^. For the baseline case, the pressure due to N^ emissions is 1.01x10' torr, whereas the pressure due to water emission is only 2.54x10 torr. The 1-0 molecules are
3. The backscattered pressure is displayed as a function of the distance between the emission source and the shield in Fig. 5. As one would expect, the pressure depends quite strongly on boom length out to about 2000-3000 cm from the source but becomes much less sensitive at greater distances. Note that the longer distances are much greater than those practical with the Shuttle remote manipulator system (RMS); these conditions therefore would be more typical of a tethered or free-flying configuration.
4. Figure 6 shows the combined effects of shield radius and distance from the emission source. The pressure is a relatively weak function of shield radius, decreasing roughly linearly with increasing radius. At 2000 cm from the source, for example, increasing the shield radius from 100 to 1000 cm results in a less than 50% decrease in pressure. Again note that, beyond about 2500 cm, the pressure at the target is relatively insensitive to both shield size and distance from the source, indicating that the most effective means of controlling the pressure behind the shield may be to increase the orbital altitude, if pressures below about 10 torr are required.