Launch and Recovery Air Pollution. The launch activity results in air quality impacts from the exhaust products of the launch vehicle and from the formation at the launch platform and dispersion of a "ground cloud" made up of exhaust gases and cooling waer along with some sand and dust. The ground cloud has the potential for creating direct public exposure to air pollutants because of its low altitude. A mathematical model has been developed to estimate the maximum concentrations of various pollutants in the ground cloud as a result of space shuttle operations. These results are not directly applicable to SPS operations because of the probable use of liquid- fueled rockets (versus solid-fueled for the shuttle) and the significantly larger launch vehicle size. The model has not yet been used for the SPS launch vehicle configuration. The Committee on Toxicology of the National Academy of Sciences/Na- tional Research Council (NAS/NRC) has recommended concentration limits for launch-related air pollutants (see Fig. 2.4) that include a short-term public limit (STPL) designed to avoid respiratory irritation and a public emergency limit (PEL) related to accident conditions that might result in some irritation but with reversible effects. Test flights and the testing of rocket engines, orbital maneuvering systems, and reaction control systems will also release air pollutants. Examination of the effects of such pollution, as well as further analysis of the ground cloud, will be included in the ongoing assessment. Launch and Recovery Water Quality Impacts. No assessment has been made of the water quality effects of the launch and recovery of SPS vehicles; however, some information is available for the space shuttle. Potential pollutants enter the water through contamination of the launch pad cooling water with engine exhaust products and removal of ablative insulation from reentry vehicles with high pressure water jets, and possibly through spillage of residual propellant if the launch vehicle is recovered from the ocean. The first two conditions can be controlled by onsite water treatment facilities and would not normally present a public health problem. Suggested maximum allowable concentrations for propellant spills are available and are shown in Fig. 2.5. The ongoing assessment will attempt to determine the ability of the SPS system to control spills to these levels.
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