EFFECTS OF SPACE-SHUTTLE FLIGHT ON THE REFLECTANCE CHARACTERISTICS OFDIFFUSERS IN THE NEAR-INFRARED, VISIBLE, AND ULTRAVIOLET REGIONS

Many remote sensing instruments employ diffuse targets for calibration . These targets usually consist of diffusers with high Lambertian char acteristics illuminated by a calibrated irradiance source. There is in creasing interest in conducting in-orbit radiance calibration checks o f remote sensing instruments using sunlight reflected off a diffuser. We report on the effects of space flight on the reflectance properties of polytetrafluoroethylene (PTFE) and aluminum diffuser samples flown on three Space Shuttle flights. These experiments showed good stabili ty of both diffuser types in the visible and near infrared but experie nced measurable degradation in the ultraviolet. Degradation varied fro m flight to flight and seemed to be related to different levels of con tamination experienced on the three flights.