Guidance and control strategies for a 12U CubeSat involved in the observation/inspection of a collaborative target

The development of technologies that enable operational capabilities that broaden the range of missions carried out by CubeSats has recently been the focus of governmental and private actors in the field of small satellites. The examination and observation of larger spacecraft (like the International Space Station) or debris is a useful example of a new small-sat mission. In this context, a TDE study developed the Space Rider Observer Cube (SROC) mission, which attempts to demonstrate the critical capabilities and technologies needed to successfully carry out an inspection mission in a safety-sensitive environment. This in-orbit demonstration could pave the way for a variety of cutting-edge CubeSat applications in the field of inspection missions. Space Rider is an unmanned spacecraft designed to provide Europe routine access and return from Low-Earth Orbit (LEO) with a space transportation system that is economical, independent, and reusable. The SROC mission consists of a 12U CubeSat deployed from the Space Rider cargo bay to closely inspect the vehicle in a safety-sensitive context with a multispectral camera. In fact, visual, near-infrared, and thermal infrared photos of Space Rider in-orbit may be useful for understanding its status and performance (e.g. heat shield deterioration), as well as for outreach. The main objective of the thesis is to define guidance and control strategies for small satellites involved in the observation/inspection of a collaborative target. Due to the difficulties in modeling internal and external disturbances and usually also in accurately measuring the system parameters, a super-twisting sliding mode control law has been proposed for the spacecraft attitude tracking. For the attitude guidance it has been used a method based on computing the Euler axis to correctly point, in each position of the trajectory, to the center of mass of Space Rider. Then, in MATLAB and Simulink environment, it has been implemented an orbital simulator where the attitude dynamics and the attitude control could be simulated. Finally, a robustness analysis through Monte Carlo simulations has been conducted.