Io’s long-debated magma ocean may not exist. Juno spacecraft data reveals that tidal forces deform the moon differently than expected if a magma ocean were present. Instead, Io’s mantle appears mostly solid, challenging old models and hinting at a more complex interior.
A new study published in Nature challenges previous claims that Io has a shallow, global magma ocean beneath its surface.
Data from NASA’s Juno spacecraft, combined with historical observations, suggests that Io’s intense volcanic activity is not driven by a vast underground magma ocean. This discovery could reshape our understanding of the moon’s interior and influence broader theories about planetary formation and evolution.
The Volcanic Power of Io
Io, the most volcanically active body in the solar system, experiences extreme geological activity due to tidal forces from Jupiter’s gravity. As Io orbits elliptically, Jupiter’s gravitational pull stretches and compresses the moon, generating internal heat. Some scientists have theorized that this process could create enough energy to sustain a global magma ocean beneath the surface, but this idea remains debated.
To test this theory, researchers analyzed measurements of Io’s tidal deformation—how much its surface flexes under gravitational stress. Juno’s recent flybys, along with historical data, allowed Ryan Park and his team to calculate the extent of this deformation. Their findings suggest that Io’s interior is not consistent with a shallow magma ocean, raising new questions about how the moon’s volcanic activity is sustained.
Solid Mantle, Not Magma Ocean
The results are not consistent with what would be expected if a shallow global magma ocean was present, which suggests that Io has a mostly solid mantle, the authors report. Whether there may be some regions of magma deep inside the moon remains to be determined, they add.
The findings indicate that tidal forces do not always create global magma oceans, which may have implications for our understanding of other moons, such as Enceladus or Europa, the authors conclude.
Explore Further: NASA’s Juno Reveals Hidden Magma Chambers Fueling Endless Eruptions Inside Io
Reference: “Io’s tidal response precludes a shallow magma ocean” by R. S. Park, R. A. Jacobson, L. Gomez Casajus, F. Nimmo, A. I. Ermakov, J. T. Keane, W. B. McKinnon, D. J. Stevenson, R. Akiba, B. Idini, D. R. Buccino, A. Magnanini, M. Parisi, P. Tortora, M. Zannoni, A. Mura, D. Durante, L. Iess, J. E. P. Connerney, S. M. Levin and S. J. Bolton, 12 December 2024, Nature.
DOI: 10.1038/s41586-024-08442-5
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1 Comment
Fascinating! If Io lacks a global magma ocean, that suggests its volcanic activity is fueled by localized magma pockets or deep mantle convection rather than a vast, interconnected reservoir. Could this mean our models for Europa’s or Enceladus’s subsurface oceans need re-evaluation too?