GROUND CHARACTERIZATION OF THE SCANNER FOR RADIATION BUDGET (SCARAB) FLIGHT MODEL-1

The Scanner for Radiation Budget (ScaRaB) is a satellite-based radiome ter for measurements of the planetary radiation budget. It was launche d in January 1994 on a Russian A METEOR-3 platform and provided excell ent data from February 1994 to March 1995. The radiometer is briefly d escribed. Onboard calibration is performed by tungsten filament lamps and blackbody simulators. The onboard sources were characterized on gr ound, as well as the spectral response function of the instrument and the linearity of the channels. The ground measurements are described a nd the results are presented. The error in the blackbody calibration i s estimated to 0.4% and to less than 1.5% for the various lamp sources . The lamp sources showed significant drifts during ground testing tha t could be corrected.