A method for monitoring solar diffuser’s bidirectional reflectance distribution function degradation in geostationary orbit

Abstract

The advanced geosynchronous radiation imager (AGRI) is a geostationary sensor whose reflective solar band is calibrated by a solar diffuser (SD). The SD bidirectional reflectance distribution function (BRDF) degrades over time in the space environment. This degradation can be measured through the SD reflectance degradation monitor (SDRDM). The SDRDM calibration data are normally collected by three filtered detectors, covering wavelengths from 0.45μm to 0.90μm. The SD reflectance degradation can be derived by trending the ratio of the background-subtracted solar-angle corrected SDRDM sun and SD view responses. The conventional monitoring methods rely on geometry factors of the sun view port and the relative BRDF of the SD, and these parameters can cause uncertainties. Aiming at these uncertain factors, the present study collects calibration data at the same solar angle. This method compares the detector digital counts obtained at different times but with the same solar angle. Consequently, it cancels out the angle-dependent parameter to obtain the ratio of the BRDF degradation factors. The obtained results show that monitoring uncertainty of the proposed method is less than 0.18%, while the corresponding monitoring error is less than 0.66%. This method can be applicated in SD's BRDF monitoring.

Solar Light Radiometry Calibration Unit for a ScanPol Polarimeter of the Aerosol-UA Space Mission

“…Spectralon was used in the APS instrument of the Glory satellite [13,22]. Various auxiliary devices are used to assess and consider the degradation of such scatterers, as mentioned in [18,20,41], and special spacecraft maneuvers are aimed at the Moon [18,20,22].…”

“…Special systems are designed for on-orbit calibration of earth-based remote sensing devices. Tey often use the light from the Sun and the Moon for calibration [13][14][15][16][17][18]. For example, the MODIS, VIIRS, and MISR multiangle radiometers [15,19,20] use the Sun's radiation for radiometric calibration.…”

Optimization design and implementation of eccentric tracking pendulum mirror for satellite-borne laser communication

“…It has the advantages of high transmission rate, strong anti-interference ability, small system terminal size, light weight, low power consumption, and can be used to establish star-star, starspace or star-ground links in space to complete wireless data transmission [4][5][6] . Satellite-borne laser communication tracking mechanism usually contains warp and weft ceremony, pendulum mirror type, periscope type, rotating optical wedge type and galvanometer type, which are suitable for the corresponding scene according to the different working angle range and weight and volume constraints [7][8] . Dues to its simple configuration, small rotating load, moderate angle range and absence of light machine coupling, the pendulum mirror tracking mechanism is suitable for high density, medium and low orbit intersatellite laser communication scenarios.…”