On-orbit calibration based upon star observation to correct thermal deformation of geostationary optical satellites

The thermal environment in a geostationary orbit is more complicated than a low orbit. Thermal deformation is a primary factor to deteriorate geometric quality of remote imaging of geostationary optical satellites. The on-orbit geometric quality testing of the SDLT-1 satellite of China shows that the light of sight (LOS) deformation in longitude and latitude are 26 pixels and 14 pixels, respectively, which do not meet the accuracy requirements. Therefore, a novel on-orbit geometric calibration method based on star observation is proposed to improve the geometric deformation. The imager embodied stars are employed as sources to evaluate the developed method and compared with the traditional procedure based upon landmarks. The results show that the geometric accuracy of the new approach is 3.2 pixels which is improved compared to traditional calibration method.