RBI Ground Calibration

The Radiation Budget Instrument (RBI) is the follow-on to the Clouds and the Earth’s Radiant Energy System (CERES) instruments, which have flown on several spacecraft since 1997. RBI will continue the record obtained by CERES of the total outgoing radiation emitted and reflected by the Earth. To obtain this record, RBI will view the Earth in three bands, a total band covering 0.35 to 100 microns, a short band from 0.4 to 5 microns and a long band from 5 to 50 microns. Data will be collected mainly in a whiskbroom mode at a sample rate of 100 Hz and 1.6x2.6 degree field of view from low Earth orbit. RBI is being built by Exelis Inc. and RBI ground calibration will be performed by Space Dynamics Lab. In addition to the broad bandpass and large field of view, RBI has strict calibration requirements, such as 0.5% or better absolute accuracy in the total band and total band repeatability over one month better than 0.067 W/m^2-sr plus 0.033% of the signal. The methods to provide a complete calibration of RBI with high accuracy will be discussed. Calibration will include RSR, non-linearity, point response function characterization, repeatability and absolute response