Io exploration with electrodynamic tethers

Abstract - Electrodynamic tethers (EDT) are a promising alternative to produce the energy required in any scientific exploration mission to Io, always handcuffed by a scarcity of power. We propose two alternatives using EDT working in the generator regime: 1) a bare self-balanced electrodynamic tether placed in an equilibrium position in the synodic frame Jupiter-Io, and 2) a rotating EDT orbiting around Io to generate permanent power and to provide propellantless orbital maneuvering capability. In the first alternative we review several tether designs addressing the benefits which can be obtained from them. In the second one, two mission scenarios are investigated; both involve a 25-km-long 5-cm-wide tape tether placed on a stable retrograde equatorial orbit around Io capable to provide kW-level useful power extracted from the fast rotating Jupiter plasmasphere. In the first scenario the tether current is controlled to provide maximum power generation. The amount of power produced and the impact on the orbit stability is investigated numerically. In the second scenario the current is controlled in order to reduce or increase the orbital energy of the system with the possibility of reaching escape velocity. Results show that EDT can be used as a permanent power production system in exploration missions to Io without compromising the orbital stability.