"Tether satellite system for active debris removal: dynamics, control and chaotic motion"
Prof. Yehia Abdel-Aziz
National Research Institute of Astronomy and Geophysics, Cairo (Egypt)

Active Debris Removal (ADR) is a critical component of space sustainability efforts, especially as orbital congestion increases with the rise of mega-constellation satellites. ADR aims to reduce the risk of collisions with operational satellites or spacecraft. There are many different conceptual methods for ADR, including robotic arms or nets to capture debris, harpoons or tether satellite systems, and techniques like ion beam shepherding or laser nudging. In this seminar, we are focusing on the Tethered Satellite System (TSS), which is a space system that uses a long, strong tether (or cable) to connect two objects in orbit - typically a satellite and a spacecraft or another satellite. TSS was developed to study tether dynamics and to explore alternative methods of propulsion and power generation in space. TSS serves multiple purposes, such as: (i) electrodynamic tethers for generating electricity by interacting with Earth’s magnetic field, (ii) propulsion and orbital maneuvering without fuel, (iii) stabilization and attitude control of spacecraft, and (iv) Debris removal, where defunct satellites can be deorbited by lowering their altitude until they burn up in the atmosphere. The dynamics and stability of TSS are studied through simulations of different satellite configurations. These studies help to determine the electric current that can pass through the tether and ensure the presence of equilibrium points in the system. Such analyses directly support the practical design of tethered satellites, improving their performance across various applications. Finally, numerical simulations are presented to confirm the controllability of electrodynamic TSS systems and to explore the potential for chaotic motion within these systems.