Solar and lunar radiometric calibration

The current generation of Earth-imaging satellites is used primarily to produce photographic quality images that are corrected for inherent non-uniformity in the focal plane (flat-fielding) and non-linearity in the sensor. The next generation of satellites requires the extraction of target reflectance with 1-2% uncertainty from these images. This requires the payload to be radiometrically calibrated to 1% uncertainty, or less. In order to achieve these levels of uncertainty, a radiometric standard is needed that is accessible from low Earth-orbit. Unfortunately, there is no such standard currently available. One common approach is to utilize man-made source standards that have calibration traceable to NIST (or other primary standards). Another method is to use detector-based standards (also traceable to NIST) and available uncalibrated sources. Unfortunately, these approaches suffer from degradation during exposure to the low Earth- orbit, which causes an unknown departure from the calibrated state (and increases the radiometric uncertainty of the standard)