The rapid growth of space exploration industry and the increasing need for debris mitigation missions have led to rising interest in Active Debris Removal (ADR) and On-Orbit Servicing (OOS) operations. Among robotic systems, Space Manipulator Systems (SMS) stand out for their adaptability and versatility, making them the preferred solution for OOS tasks such as satellite grasping, berthing, repair, and maintenance. Consequently, the design of proper strategies to control them have become critical. However, these control laws are often ineffective due to the strongly coupled dynamics of space systems and the difficulty in estimating the characteristics of the target. This Master's thesis aims to find new control strategies that contribute to address this problem, by proposing a robust control against the disturbances and perturbations that derive from the capture of an unknown target.