Correction Method for Thermal Deformation Line-of-Sight Errors of Low-Orbit Optical Payloads Under Unstable Illumination Conditions

Accurate optical axis pointing of optical payloads in low orbits is essential for sustained indication and high-precision positioning of motion targets. Owing to the short orbital period in low orbits and the influence of the sun, the incident light on the optical payloads and the space thermal environment undergo drastic and irregular changes over a short period. These changes cause optical distortions within the camera and variations in the installation matrix referenced for the satellite. Ultimately, these changes affect the imaging process of the camera and the line-of-sight (LOS) accuracy, greatly disadvantaging the high-precision pointing and positioning of space targets. In this paper, a correction method based on stellar observation data is proposed to address the LOS deviation issue of low-orbit optical payloads caused by space thermal deformation (STD). The proposed method innovatively utilizes the angle relationship between the solar vector, the satellite position vector, and the camera LOS vector as the correction parameters to characterize the thermal environment in which the payload operates. This method overcomes the irregularity and frequent correction requirements of LOS errors in low-orbit payloads. Experimental results showed that the mean absolute error of the camera LOS after the correction was 0.001096 rad, representing an 80.28% improvement over previous measurements, even reaching 99% improvement in the final mission. At a 95% confidence level, the correction errors for the final mission were consistently below 10−4 (2σ) rad in the right ascension and declination directions.