Measurement of Optical Radiations in Spacecraft Environments

Three topics in remote sensing of the gaseous and particulate environment of spacecraft are reported and several further optical contamination and induced-glow phenomenology issues now under consideration are briefly reviewed. The transmission to ground stations of the near-ultraviolet radiation from OH excited when high-kinetic energy water molecules in thruster rocket exhaust react with the ambient oxygen atoms is calculated from band and atmosphere models, and the measurement signalnoise is shown to depend on the concentrations of both UV-absorbing ozone molecules and UV sky background- producing O atoms along the view path as well as on the spatial distribution of radiance from the exoatmospheric collision volume. Vacuum-ultraviolet photolysis of water vapor off spacecraft with radiometry of the resulting electronically- excited, microsecond lifetime hydroxyl radicals is shown to be a feasible means for determining its rates of offgassing, and preliminary designs for such active probes are presented. An initial review of the potential for identification of spaceborne particulates from their chemical composition-dependent scattering and emission of visible and infrared quanta indicates these synthetic instrument response-convolved spectra of candidate contaminant particles are need to evaluate the concept. Keywords Rocket exhaust gases Volume Space shuttle Spacecraft rams Atmospheric limb Video images Infrared images Spacecraft dumping Water dumping Spacecraft contamination Optical glows Radiometry.