On-Board Thermal Motion Compensation Method for Pointing Errors of the Remote Sensor Aboard a Three-Axis Stabilized Geostationary Satellite

For earth observation from a three-axis stabilized geostationary (GEO) remote-sensing satellite, a highly accurate onboard thermal motion compensation (TMC) method for real-time correction of the satellite sensor's line-of-sight (LOS) pointing error due to thermally induced structural distortion internal to the sensor during the diurnal cycle remains a global concern to date. In this letter, we propose a novel TMC method for GEO sensors. Compared with the traditional TMC methods, this method has the following two advantages. First, we define the LOS misalignment angle to model the comprehensive impact of the sensor's internal thermal misalignment angles on the sensor's LOS pointing behavior, which makes the optical path modeling simpler and more generic. Second, we fit the repeatable diurnal variations of the LOS misalignment angle based on long time-series star observations; therefore, the calculation and the use of the TMC amount are no longer limited to the assumption that the sensor's internal thermal misalignment angles remain constant within a certain period of time, as in the traditional method. The proposed TMC method is theoretically applicable to all types of GEO sensors, including optical and microwave sensors, and is verified by Fengyun-4A advanced geosynchronous radiation imager (FY-4A/AGRI) TMC experiments.