Design considerations for a passive electrodynamic tether

Defunct satellites and increasing volume of space debris create challenges for a sustainable space for future missions, due to increased congestion and a higher risk of collisions. Implementing de-orbiting strategies for satellites at the end of their mission life is crucial to mitigate the risk. Electrodynamic tethers (EDTs) can generate thrust for fuel-less propulsion by harnessing the interaction between the tether and the Earth’s magnetic field. A passive EDT system, operating in power generation mode, can be utilized as an autonomous de-orbiting system by relying solely on the motional electromotive force to sustain current flow and operate the electrical subsystem without continuous spacecraft power. While previous EDT missions primarily focused on large-scale systems using very long tethers, the emergence of CubeSats and other small spacecrafts necessitates a review of EDT design principles. This paper aims to provide a foundational framework for engineers, outlining the fundamental principles and key design considerations for implementing EDT systems across a range of spacecraft sizes and orbital regimes. This work focuses on demonstrating the operating conditions and desired output (de-orbiting time, low mass, and adequate thrust generation) that define the characteristics of the EDT system. By considering multiple criteria and trade-offs, this review provides design considerations for mission-specific passive EDT systems for end-of-life missions. A simplified electrical system architecture is presented to facilitate the development of autonomous EDT systems. Furthermore, the study examines the influence of external factors, including solar conditions and orbital parameters, on EDT performance and design characteristics.