The third option is considered as a means for removing the SPS satellite permanently from space. In this option the satellite is impacted on the lunar surface. Naturally any such impact would have to be carefully coordinated with lunar activities at the time of impact. Although it might be possible to recover some of the SPS materials after impact, this is not accepted as a realistic benefit of this mode of disposal at this time. The fourth disposal option considered is removal of SPS satellites to a heliocentric orbit such as 0.8 AU. This option removes the SPS satellites sufficiently far from the earth that they are effectively gone forever. The energy requirement for this mode of disposal is, of course, dependent upon the heliocentric orbit into which the satellite is placed. The final disposal option considered is earth reentry. This disposal option arouses some amount of interest because of the possibility of recovering some SPS materials for reuse on earth if the reentry can be sufficiently wellcontrolled. Unfortunately, however, this mode of disposal not only requires the highest energy increment and is, thus, the most expensive disposal option, it probably is not acceptable due to environmental and risk considerations, especially in light of the absurd extent to which the Skylab reentry risks were escalated in the media. Within each of the above disposal options there exists several suboptions. The principal suboptions include the trajectory mode and thrust level for the disposal mission. It is envisioned that the disposal would occur using argon thrusters at a 10,000 s specific impulse. Disposal could be by means of the last flight of a COTV. The COTV could use its own power supply or it could be augmented by power provided from the SPS satellite. In the event that it uses its own power, the SPS satellite could be disposed of in varying states of salvage incuding one in which essentially all of the solar arrays have been removed. In the
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