Exploration of the Jupiter Plasma Torus with a self-powered electrodynamic tethers

Abstract

The dynamics and power generation of an electrodynamic tether (EDT) placed in the three body system formed by Jupiter, Io and the spacecraft are analyzed. In the region surrounding Io?s orbital path, a region of increased electron density called the plasma torus offers a suitable location to operate an EDT. The electrodynamic interaction between the conducting cable of the EDT and the strong magnetic field of the planet leads to non-negligible electrodynamic force, that perturbs the natural three body motion. New equilibrium positions are found in the synodic frame, which coincide with the classical triangular Lagrangian points only when the electrodynamic force vanishes. The locations of equilibrium positions are computed as a function of tether length, width and spacecraft mass. While in this equilibrium position, the tethered system can generate kilowatts of electrical power without deorbiting the system, the energy coming from to the super-rotating plasma sphere of Jupiter. The motion around the new equilibrium positions is evaluated, for both small linear motion confined to a neighborhood of the equilibrium point, and for large amplitude non-linear motions. As an application of this study, a misión profile capable to explore the whole plasma torus is presented. This plasma torus explorer can perform an internal ?scan? of the torus itself while generating electrical power useful for loads on board the spacecraft.