Flat Plate Radiometer (FPR)

Description

The flat plate radiometer (FPR) system was designed to provide a measurement of the global distribution of reflected solar and longwave radiation leaving the earth. The FPR system consisted of four detectors, and analog-to-digital converter, and a tape recorder. The detectors had a hemispheric field of view of 2 pi ster and were mounted on the satellite baseplate facing earth. The detectors used coated aluminum discs as a sensing element. Two of the discs were white and responded only to infrared energy (7 to 30 microns) radiated from the earth and its atmosphere. The other two discs were painted black and had a broader band sensitivity (0.3 to 30 microns). Two discs (one fo each type) had a thermistor bolometer mounted on the back surface to measure the disc temperature. The other two discs used thermopiles. An identical experiment was flown on ITOS 1, and similar experiments were flown on ESSA 3, 5, 7, and 9. For a full description of the FPR system, see 'Studies in atmospheric energetics based on aerospace probings, annual report - 1967,' pages 179 to 189, Dept. of Meteorology, University of Wisconsin, March 1968. The FPR functioned normally from launch until May 29, 1971 when the incremental tape recorder failed, resulting in total data loss.