ABSTRACT A simple time-dependent analytic formalism is developed and utilized to predict the influences of transport, photodissociation, and frequency of injection on the global redistribution of water deposited in the earth's upper atmosphere by repeated launches of large rockets. As an example, possible future Satellite Power System (SPS) activities are simulated by injections of 7.0 x 10$ 1 molecules of ^0 between 70 and 120 km by second stages of heavy lift launch vehicles (HLLVs), with launch frequencies ranging between 8 day-1 and 2 week \ Generally, measurable environmental effects are found to occur when the mesospheric water vapor mixing ration (x) exceeds 100 ppmv, which can occur over areas of the order of 20,000 kmz for the SPS scenarios adopted here. Possible environmental effects quantitatively evaluated for x>100 ppmv include: (a) a 50% reduction in D-region ionization due to screening of L radiation by water (and a smaller contribution, by thermospheric hydrogen produced by photolysis of the injected H^O below 120 km); (b) an additional 50% reduction of D-region ionization resulting from conversion of ambient N0+ and 02+ ions to heavy water cluster ions that possess more rapid recombination rates; and (c) at least a doubling of OH concentrations below 100 km. Radiative cooling produced by the injected ^0 is found to have a negligible effect on the general circulation of the mesosphere and lower thermosphere, and at mid-latitudes mixing ratios of order 10J ppmv would be required to reach the frost-point temperatures necessary for the maintenance of clouds at the mesopause. Qualitatively, atomic hydrogen released by photolysis of ^0 is expected to increase the loss rate of ozone between 75 and 95 km, to significantly increase OH concentrations and accompanying airglow emissions, and also act to increase nighttime E-region ionization by geocornonally scattering L and LR radiations after diffusing into the upper thermosphere. These effects of hydrogen released by ^0 photolysis may indeed encompass the most important upper atmosphere environmental impacts to be researched.
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