Electrodynamic tethers in space: dynamical issues, solutions and performance

Electrodynamic tethers are a promising new technology for a variety of applications ranging from deorbiting of spent satellites and upper stages in low Earth orbits to propellantless propulsion around any planet (inclusive Earth) with a magnetic field and a plasmasphere. However, the continuous application of electrodynamic forces/torques over a relatively long period of time raises dynamical issues related to the tether attitude dynamics that need to be solved for achieving longterm dynamical stability. The paper addresses firstly the fundamentals of the dynamical motion forced by the electrodynamic forces/torques and secondly reviews the techniques used to control the motion generated by those forces/torques. The paper also presents the techniques that were used successfully in simulation to control the dynamics of a tethered system designed for deorbiting spent satellites in low Earth orbits and shows its deorbiting performance at all orbital inclinations. Copyright © European Space Agency