Abstract
Maintaining the radiometric accuracy of the 140-satellite Planet Dove constellation has required the development of a more automated approach to on-orbit radiometric calibration given the number of satellites and the operational behavior. In nominal operations, Dove Satellites are non-tasking and are nadir pointing. A methodology has been developed that utilizes a hybrid approach to combine lunar calibration and cross calibration to enable on-orbit absolute radiometric calibration of each individual Dove satellite. The cross-calibration approach utilizes instantaneous crossovers in spectrally characterized pseudo-invariant calibration sites with RapidEye, Landsat8, and other Dove satellites. Lunar Calibration utilizes an implementation of the ROLO model [1] and daily moonshots taken by each satellite during both the waxing and waning moon phases. This approach is automated, with new crossovers for each satellite processed and stored daily, and moonshots on a monthly cadence. This has allowed for regular monitoring of the radiometric calibration for each satellite and regular updates to ensure calibration accuracies. Initial validation of this approach using 40 Dove satellites shows an uncertainty of 5% at 1-sigma is achieved across all satellites using instantaneous crossovers with Landsat8 as a validation dataset. This paper describes the absolute radiometric calibration approach, how this method will scale to the larger 140 satellite constellation, and a discussion on the initial results.
[1] Hugh H. Kieffer and Thomas C. Stone, "The Spectral Irradiance of the Moon", Astronomy. J. 129, 2887-2901 (2005)
In-Orbit Radiometric Calibration of the Planet Dove Constellation
Maintaining the radiometric accuracy of the 140-satellite Planet Dove constellation has required the development of a more automated approach to on-orbit radiometric calibration given the number of satellites and the operational behavior. In nominal operations, Dove Satellites are non-tasking and are nadir pointing. A methodology has been developed that utilizes a hybrid approach to combine lunar calibration and cross calibration to enable on-orbit absolute radiometric calibration of each individual Dove satellite. The cross-calibration approach utilizes instantaneous crossovers in spectrally characterized pseudo-invariant calibration sites with RapidEye, Landsat8, and other Dove satellites. Lunar Calibration utilizes an implementation of the ROLO model [1] and daily moonshots taken by each satellite during both the waxing and waning moon phases. This approach is automated, with new crossovers for each satellite processed and stored daily, and moonshots on a monthly cadence. This has allowed for regular monitoring of the radiometric calibration for each satellite and regular updates to ensure calibration accuracies. Initial validation of this approach using 40 Dove satellites shows an uncertainty of 5% at 1-sigma is achieved across all satellites using instantaneous crossovers with Landsat8 as a validation dataset. This paper describes the absolute radiometric calibration approach, how this method will scale to the larger 140 satellite constellation, and a discussion on the initial results.
[1] Hugh H. Kieffer and Thomas C. Stone, "The Spectral Irradiance of the Moon", Astronomy. J. 129, 2887-2901 (2005)