The necessity of the removal of inactive spacecraft (especially large and heavy ones) has been proposed for more than 20 years. In several studies, many different concepts have been developed. The use of a tether with a net or harpoon seems a promising solution. In an Active Debris Removal (ADR) mission a fast stabilization of the target is indispensable. So a safe and secure de-orbiting can be assured to avoid for example a collision of the chaser and target in space that will produce a quantity of new fragments that may cause additional collisions or fragmentation. To ensure the safety of an ADR mission an, active control of the Tethered Space System (TSpS) is required. Therefore, the dynamics and the transmission capabilities of the tether needs to be analyzed. Each maneuver performed by the chaser has an influence on the flexible connected target. So the TSpS needs to prevent any winding or high oscillation situations. At the Institute of Space Systems (IRAS) a Tether Dynamics Toolbox (TDT) is under development. In comparison to some existing models (in the field of tether dynamics) the IRAS TDT considers the end-bodies (chaser and target) and the tether model itself to take into account the complete ADR system. This separation offers also the chance to integrate different approaches to model the tether. Eventually it is planned that the TDT user can decide between three different tether model approaches, depending on the tasks and analysis that should be done. Key element of the TDT will be the capability to perform analysis and the stability of ADR systems, therefore a Guidance, Navigation and Control (GNC) module will be integrated. The module also includes the integration of losses and damping effects in the tether that can have an influence on the motion of the system. Basically the chaser performs a maneuver (thruster firing), the tether transmits the signal, the target reacts and the feedback on the chaser will be analyzed to ensure a stable orbital flight. Through this paper the general toolbox architecture shall be presented. Furthermore the concept of separation for the propagation of the end-bodies (chaser and target) and the tether itself is explained. Consolidations and objectives of the development and the approaches are introduced.
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