beam pointing failures. Many years of range safety successes mitigate the former concern, and it is presumed that fail-safe devices will assure transmission cut-off in case of any major beam misdirection due to satellite attitude control or stationkeeping failures. Radio frequency interference (RFI) may be an important concern. Evidence exists that potential degradation of some defense, police and ship radars could occur. As noted below, ionospheric modifications due to interactions with the beam might also affect high frequency communications and other uses of the ionosphere. b. Environmental Pollution Land disturbance and air water pollution caused by the materials extraction and manufacturing processes involved in the implementation of an energy satellite system appear to be negligible. Health effects due to SO^ emissions, for example, have been estimated to be less than 2% of those of a coal-fired plant, and 25% of a nuclear plant's ope rations. The primary pollution problems arise from the flight operations of the energy satellite systems. They begin with noise due to the baseline 360 shuttle launches per year, which can, however, be mitigated by a sufficiently large launch area. Sonic booms at the recovery area may also be a problem. No information is yet available on these factors. Of greater consequence is launch area, atmospheric and ionospheric pollution due to propellant residues and lower staging fragments of the boost to low earth orbit (LEO), transfer to geostationary earth orbit (GEO), and stationkeeping and attitude control in GEO. Particular concern exists regarding detrimental effects on the ozone layer, with consequent increases in the transmission of ultraviolet radiation and thereby of the incidence of skin cancer. These effects could arise due to the large quantities of H^O and NO^ that would accrue from the large number of flights. For example, a 2% increase in ^0 above normal might occur at the 25-30 mile (40-50 km) altitude range. This is believed to be inconsequential, however. (It is much less than the estimated emissions of an SST fleet of 500 aircraft once of concern.) An incremental flux of
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