Landsat-7 Enhanced Thematic Mapper Plus In-Flight Radiometric Calibration

The Enhanced Thematic Mapper Plus (E,TM-k) for the Landsat-7 satellite is currently in the assembly and integration stage with the satellite due for launclh in 1998. The ETM+ is a derivative of the earlier Thematic Mappers (TM??s) flown on Landsats 4 and 5. Chief among changes designed to improve radiometric calibration accuracy is the Full Aperture Solar Calibrator (FASC), a diffuse reflecting plate that can be deployed in front of the ETMt aperture. With knowledge of the reflectance and illumination geometry of this calibrator, an absolute radiometric calibration of the ETM+ can be performed in flight by reference to the sun. Also incorporated on the ETM+ is a Partial Aperture Solar Calibrator (PASC) which can perform more frequent, but less complete calibrations of the ETM+. These two calibration devices, along with an Internal Calibrator similar to the one on the earlier TM??s, constitute the on-board calibration capability. Ground Look calibrations will supplement `the on -board measurements