Initial Application of Intra-Fleet Simultaneous Crossovers for Rapid Commissioning of New Satellites
Abstract
Planet owns and operates a large fleet of medium resolution CubeSats. These satellites, named Doves and SuperDoves, provide monitoring of the world’s full land surface on a near-daily basis. For accurate production of radiance based imagery, SuperDoves are calibrated on orbit using Sentinel-2 as reference due to the close similarity between the spectral responses of their corresponding spectral bands. As older satellites age out of production use due to orbital decay or technical issues, new satellites are launched to maintain coverage. When launching these new satellites, it is important to execute commissioning activities quickly so that coverage continuity is maintained without interruption.
Current launch commissioning includes a calibration update that uses simultaneous crossovers with Sentinel-2 to determine corrections to apply, the same approach used for the normal biannual updates to SuperDove calibrations. Therefore, the radiometric commissioning time is dependent on acquiring a sufficient number of good quality, near simultaneous crossovers for each satellite to provide a high confidence in the derived calibration corrections. In practice, deriving initial calibrations for SuperDove satellites using Sentinel-2 as a reference requires a minimum of three to four weeks to provide calibrations with a marginal degree of confidence. In contrast, high confidence calibrations can be obtained using Dove-Dove crossovers in less than week, followed by independent validation in a similar timeframe, with the same number of high quality crossovers normally used for standard on-orbit calibration updates.
Initial Application of Intra-Fleet Simultaneous Crossovers for Rapid Commissioning of New Satellites
Planet owns and operates a large fleet of medium resolution CubeSats. These satellites, named Doves and SuperDoves, provide monitoring of the world’s full land surface on a near-daily basis. For accurate production of radiance based imagery, SuperDoves are calibrated on orbit using Sentinel-2 as reference due to the close similarity between the spectral responses of their corresponding spectral bands. As older satellites age out of production use due to orbital decay or technical issues, new satellites are launched to maintain coverage. When launching these new satellites, it is important to execute commissioning activities quickly so that coverage continuity is maintained without interruption.
Current launch commissioning includes a calibration update that uses simultaneous crossovers with Sentinel-2 to determine corrections to apply, the same approach used for the normal biannual updates to SuperDove calibrations. Therefore, the radiometric commissioning time is dependent on acquiring a sufficient number of good quality, near simultaneous crossovers for each satellite to provide a high confidence in the derived calibration corrections. In practice, deriving initial calibrations for SuperDove satellites using Sentinel-2 as a reference requires a minimum of three to four weeks to provide calibrations with a marginal degree of confidence. In contrast, high confidence calibrations can be obtained using Dove-Dove crossovers in less than week, followed by independent validation in a similar timeframe, with the same number of high quality crossovers normally used for standard on-orbit calibration updates.