FLASHLAMP INSTRUMENTS FOR MEASURING THE MIDCOURSE SPACE EXPERIMENT SATELLITE CONTAMINATION ENVIRONMENT

The xenon flashlamp (XF) and krypton lamp and radiometer (KLR) are two of a suite of instruments that monitor the particulate and gaseous co ntamination environments of the Midcourse Space Experiment spacecraft. The near-field particulate measurement comprises the high-intensity X F that illuminates a volume of space in the field of view of a wide fi eld-of-view visible imager. Radiation scattered by illuminated contami nant particles is imaged. The intensity of the radiation is related to a particle's size and composition. The particle's track yields inform ation about its velocity and trajectory. From ground calibration data we estimate a sensitivity to detect particles smaller than 1 mm and to determine cross-field velocities from 1 mm s(-1) to 50 m s(-1). We pr esent early mission particulate data from known particle-generating ev ents and from comparatively quiescent times. These results are consist ent with previous measurements. The KLR measures the local H2O density in a volume of space approximately 0.5 m from one corner of the space craft. The instrument comprises an array of krypton vacuum ultraviolet line source lamps that dissociate H2O and a near-UV radiometer that d etects the chemiluminescence from the OH dissociation products. Ground calibrations indicate that the instrument has sufficient sensitivity to detect H2O densities as low as 1.5 X 10(7) molecules cm(-3). H2O is the primary outgassed species during the early part of a spaceflight, and is a particular concern to cryogenic sensors, such as the Spatial Infrared Imaging Telescope III (SPIRIT III) on this spacecraft. Early mission results are in overall agreement with prelaunch predictions. (C) 1998 American Institute of Physics. [S0034-6748(98)00811-9]