Qualification of bracket design for star tracker: numerical and experimental evaluation

Star tracker (STR) is an important instrument for satellite pointing requirements. Due to its position on the spacecraft, an extensive analysis was undertaken for the qualification of STR regarding the launch environment to overcome a larger acceleration response value under random excitation and thermal environment in orbit. This work focuses on the design of STR bracket which was studied to ensure structural and thermal stability during the satellite mission. Consequently, various model designs of brackets were analysed to satisfy the pointing and dynamic characteristics. The stiffness of the star sensor bracket was conducted based on the finite-element method and experimentally. Moreover, temperature data were obtained from the thermal analysis under the extreme operating conditions in orbit and mapped to the satellite structural model to calculate the thermal distortion. The results show that the main modes are achieved as required. In addition, according to the satellite reference system, the maximum angle change between the optical axis of the star sensor and the camera is 7.06 mdeg. Furthermore, the bracket was tested under random vibration integrated into the proto-flight model to validate the designed performance without any issues. The structural and thermal stability of the star sensor support is suitable for the mission, which can meet the requirements of attitude accuracy.