Accession Number : ADA325759

Title :   Influence of the STS-78 Space Shuttle Exhaust Plume on Column Ozone Abundance Inferred from Ground-level Solar UV Spectra,

Corporate Author : AEROSPACE CORP EL SEGUNDO CA EL SEGUNDO TECHNICAL OPERATIONS

Personal Author(s) : McKenzie, D. J. ; Gutierrez, D. J. ; Hecht, J. H.

PDF Url : ADA325759

Report Date : 15 FEB 1997

Pagination or Media Count : 19

Abstract : The ground-based prototype of the High Resolution Ozone Imager (HIROIG), an imaging spectrograph that was operated in the wavelength range 275-360 nm, was deployed at Kennedy Space Center on June 19-21, 1996 to make observations before, during, and after the launch of the STS-78 space shuttle mission. The instrument measured the ultraviolet (UV) spectrum of direct sunlight at the ground every 74 s for several hours during each of the three days. The objective of the campaign was to search for evidence of stratospheric ozone depletion in the launch plume. To accomplish this, we examined, as functions of time, several spectral ratios that are sensitive to the total column ozone abundance along the line of sight to the sun. The spectral ratios yielded no evidence of column ozone depletion caused by the launch plume as it occulted the sun. The upper limit, at the 95% confidence level, on column ozone depletion for the entire lO-min period during which the plume was between the spectrograph and the sun was 3.4%. Since the potential harmful effect of ozone depletion, increased ultraviolet radiation at the ground, may be mitigated by increased scattering or absorption by rocket-plume aerosols, we also examined the absolute intensities at 300.8 and 307.5 nm wavelengths. There was no evidence of significant reduction in UV intensity attributable to the effects of plume aerosols, but the absolute flux measurements were complicated by the intermittent obscuration of the sun by tropospheric clouds. The upper limit on UV attenuation by scattering from plume aerosols is approximately 15% at 300.8 nm.

Descriptors :   *EXHAUST PLUMES, *CHLORINE, *STRATOSPHERE, *ULTRAVIOLET SPECTRA, DEPLETION, AEROSOLS, IMAGES, LAUNCHING, TROPOSPHERE, SOLAR SPECTRUM, SOLID ROCKET PROPELLANTS.

Subject Categories : Atmospheric Physics
      Ultraviolet Detection and Detectors
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE