Vibration load compliance of a miniaturized CubeSat quantum communication terminal

CubeSats are a promising platform for the implementation of the space segment in future satellite quantum key distribution constellations. This work demonstrates the design optimization regarding the structural dynamics of the OSIRIS4QUBE quantum communication terminal and the validation of its compliance with launch and operational vibration loads. A representative simulation model is constructed, which allows for the optimization of the system. The goal is to adapt its modal characteristics to isolate it from the resonance of the fine pointing system. Since the modifications are to be decoupled from the optics design, only the printed circuit board, which serves as the optical bench, is adapted. Additionally, customized dampers are used to flatten the response curve of residual vibrations in the critical band. The payload is subjected to a vibration test to validate the simulations and demonstrate the integrity of the fast steering mirror, which revealed a resonance separation factor of 1.28 between the actuator and the optical terminal. In addition, the influence of micro-vibrations from the reaction wheels on the fine pointing mechanism is analyzed. A 3 σ tracking error of 72μ rad is measured, proving that the pointing requirements are still met under the most adverse onboard operational conditions.