On-Orbit Calibration Method for Rotation Axis Misalignment in Rotating Mirror-Based Wide-Field Space Cameras

Rotating mirror-based space cameras are susceptible to mirror misalignment due to the severe vibrations experienced during rocket launch and the harsh, variable conditions of the space environment, which can result in deviations of the camera’s line of sight. To mitigate this risk, this study proposes a simulation-based on-orbit calibration method for quantifying rotating mirror misalignment using a system of pointing vector equations. The method employs star coordinates as a reference to establish the reference pointing vector for stars, while simultaneously developing a model of the rotating mirror imaging system. By incorporating a misalignment matrix, the actual pointing vector of star points is derived. Subsequently, the reference star pointing vector and the actual star point pointing vector are combined to formulate a system of pointing vector equations. Solving these equations enables precise measurement of the rotating mirror’s rotational misalignment without requiring additional spaceborne equipment. Through simulations, the three-axis misalignment of the rotating mirror is deduced from imaging pixel coordinates, given the known right ascension and declination of reference star points. The influence and patterns of three-axis misalignment on pointing accuracy are analyzed separately. Although validation based on real measurement data remains to be carried out in future work, this simulation-based method provides a theoretical foundation for the calibration of internal orientation elements of space cameras equipped with moving components.