A Proposed Two-Stage Two-Tether Scientific Mission at Jupiter

A two-stage mission to place a spacecraft (SC) below the Jovian radiation belts, using a spinning bare tether with plasma contactors at both ends to provide propulsion and power, is proposed. Capture by Lorentz drag on the tether, at the periapsis of a barely hyperbolic equatorial orbit, is followed by a sequence of orbits at near-constant periapsis, drag finally bringing the SC down to a circular orbit below the halo ring. Although increasing both tether heating and bowing, retrograde motion can substantially reduce accumulated dose as compared with prograde motion, at equal tether-to-SC mass ratio. In the second stage, the tether is cut to a segment one order of magnitude smaller, with a single plasma contactor, making the SC to slowly spiral inward over several months while generating large onboard power, which would allow multiple scientific applications, including in situ study of Jovian grains, auroral sounding of upper atmosphere, and space- and time-resolved observations of surface and subsurface.