Retrieval Strategies for Tethered Satellites

Space tethered systems are attracting a lot of attention from the scientific community since they have proved to be promising devices for a wide range of applications. The two most critical phases of tethered systems are the deployment and the retrieval maneuvers of the tether. Even though similar, the deployment and the retrieval have difficulties inherent to each of them. The retrieval must fulfill demanding stability issues, and its control strategy has to provide adequate energy dissipation because, due to the conservation of the angular momentum, rewinding the tether makes the system dynamics unstable. Moreover, the retrieval must be able to avoid undesirable events, such as jamming or winding the tether around the main spacecraft. This paper aims at investigating the retrieval dynamics for satellite tethered missions. A numerical simulator developed in MATLAB is introduced, presenting the model of a space tethered system that involves very complex phenomena. In the simulator, control strategies for the retrieval maneuver are numerically implemented to stabilize the system dynamics and their performance is evaluated considering both ideal and non-ideal scenarios.