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Chemical Interactions and Light Emissions from Vented Species

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Final rept. Jun 1988-Mar 1989

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Airglow emissions may be induced by the interaction of atmospheric constituents with vapors released from space vehicles. Such emissions can be produced by a number of chemical mechanisms. This study considers neutral-plasma reactions as well as neutral-neutral reactions as the sources for excited species. The intensities of light emissions produced by the release of water and methyl alcohol into the upper atmosphere is estimated with a numerical mode. Chemical reactions between the injected neutrals, background ions, electrons, and neutrals, and artificially created ions and neutrals are considered. We find that OH is the primary excited species resulting from the water release. Vibrational and electronic states of OH will be excited to yield emission spectra between 240 and 4400 nm wavelengths. For the release of 10 to the 26th power molecules in the nighttime ionosphere with a density of 10 to the 6th powercu. cm, the intensities of the emissions will be greater than .0001 Rayleights. The water release also produces vibrational states of H2O and electronic states of atomic oxygen. The addition of methyl alcohol to the release causes substantial production of vibrationally excited formaldehyde. We conclude that the venting of reactive molecules into the upper atmosphere at 300 km altitude or above can produce excited species by neutral-neutral, ion- neutral, or electron-ion reactions. No one reaction process is dominant in the F-region. Keywords Ionospheric modification, Infrared emissions, Visible emissions, Ultraviolet emissions, Vehicle outgassing. AW

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  • Atmospheric Physics

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