Skip to content

New science results about extremely active volcanism on Jupiter's moon Io: Implications for future exploration

Alfred S. McEwen , IVO Team

Abstract

Recent Io results have come from telescopic observations and from Io flybys by the Juno mission.  De Kleer et al. (2024, Science 384) used submillimeter observations of Io's atmosphere to measure sulfur isotopes and found 34S/32S to be highly elevated compared to average Solar System values. They interpret this to mean that Io has lost 94 to 99% of its available sulfur and has been volcanically active for most of its history.   Juno observations show new eruptions (Ravine et al., in progress) and revealed that many hot spots consist of hot rings suggestive of lava lakes (Mura et al., in press).  The Juno and other data shows the polar regions may be less active than equatorial regions (Davies et al., 2024, PSJ 5), important to understanding the depth of tidal heating, but Juno cannot detect all of Io's heat flow and longer-wavelength observations are needed.  Juno acquired gravity data to measure tidal k2 as a test for a magma ocean with a detached lithosphere (Park et al., in progress).  New models for the distribution of melt in Io may be needed to satisfy the gravity result, the induced magnetic signature (Khurana et al., 2011, Science 332), and other observations.  The Io Volcano Observer mission completed a Phase A study for Discovery in 2021 and was updated in 2023 for a New Frontiers 5 opportunity (Hamilton et al., PSJ in progress).  We will discuss how a future Io-dedicated mission could address the science questions raised by the new results.