| Abstract |
Jupiter's moon Io, the world with the greatest tidal flexing, volcanic and tectonic
activity, and mass-loss in our solar system, begs for dedicated exploration.
Missions such as Juno, JUICE, and Europa Clipper, along with Earth-based telescopes
such as JWST and ALMA, will acquire important Io observations over the next 15
years. However, a mission designed for Io science is needed for key advances, to
contribute to understanding the early evolution of terrestrial planets,
tidally-heated exoplanets and ocean worlds, and magnetospheric physics across the
galaxy. The NASA Discovery-class Io Volcano Observer concept study demonstrated how
10 carefully designed close Io flybys could determine the melt distribution in Io's
interior--confirming or refuting the purported magma ocean, determine Io's
lithospheric structure, determine where and how Io is losing heat, and determine
Io's volatile loss processes and rates. Such encounters would also measure Io's
rate of orbital migration, key to determining the stability of the LaPlace resonance
that heats Europa and Ganymede as well as Io. The science payload included a
magnetometer, plasma instrument, narrow- and wide-angle cameras, thermal mapper, and
neutral mass spectrometer. There may be an opportunity in 2023 to propose an Io
mission in NASA's New Frontiers program, so how might that differ from a
Discovery-class mission? An Io orbiter to provide the best geophysical measurements
would be very challenging deep inside Jupiter's gravity well and high radiation
zone. Or the IVO concept could be augmented with a radiation design to support more
than 10 encounters and use of Ka-band downlink telemetry to improve the data return
capability and gravity science. There are many other science instruments that would
be valuable additions. Small spacecraft might be released to explore close to Io's
surface. International collaboration will certainly be important.
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