THE FUTURE OF IO EXPLORATION

Jupiter’s moon Io is arguably the most geologically active solid body in the Solar System beyond Earth. Io undergoes severe tidal heating, induced by the orbital eccentricity forced by Jupiter and the Laplace resonance between Io, Europa, and Ganymede. Io’s high global heat flow presages an extremely rich array of geophysical, geological, geochemical, atmospheric, and magnetospheric phenomena operating at a scale not seen active anywhere else in our Solar System. Unlike any other place in the Solar System, Io is remarkable in that geological processes can be observed as they happen. Io is also the best place in the Solar System to study tidal heating, a process that is fundamental to the evolution of giant planet satellite systems, and one that may greatly expand the habitability zone in extrasolar systems. Io is directly linked to the evolution of the one of most promising sites for extraterrestrial life, Europa. By studying the time-variable orbital and thermal evolution of Io, we gain a better understanding of time-variable tidal heating of Europa, with obvious implications for the sustainability of its putative subsurface ocean and history of habitability. An Io-dedicated mission that operates in the 2013-2022 timeframe could identify key parameters involved in orbital-thermal evolution. This presentation will review the science of Io, and objectives and proposed mission concepts for future exploration of Io in the next decade and beyond. Future Io exploration is recommended to include: 1) a Jupiter-orbiting Io Observer spacecraft of either Discovery-class or New Frontiers-class; 2) a space-based UV telescope with diffraction-limited capability; 3) space-based missions that enable long-term monitoring of Io over a variety of time scales (seconds, minutes, hours, days, months, years); and 4) expanded time for Io observation on ground-based 8- to 10-m class telescopes, particularly those with nighttime Adaptive Optics capability.