Recent research published in Nature has raised questions about the volcanic processes occurring on Jupiter’s moon Io, particularly the absence of a global magma ocean beneath its surface. Data collected by NASA’s Juno spacecraft, combined with historical information from the Galileo mission, shows that Io’s interior is more solid than previously thought. This revelation has implications not only for Io, but also for our understanding of tidal heating in other celestial bodies.
Juno and Galileo’s discovery reveals a solid interior
According to the report, scientists led by Ryan Park of NASA’s Jet Propulsion Laboratory have analyzed data from Juno’s close fly-by of Io between December 2023 and February 2024. These measurements, along with Galileo’s archival data, focused on Io’s gravitational field and its deformation under Jupiter’s intense gravitational pull. It was found that Io’s hardness rules out the possibility of a moon-wide ocean of molten rock. Previous theories based on magnetic induction data and the distribution of volcanic activity had suggested that such an ocean might exist to facilitate the movement of heat beneath Io’s surface.
Investigation into the source of the lava continues
According to reports, Io is home to around 400 active volcanoes, with its surface covered with extensive lava plains. Without a magma ocean, the molten rocks erupting from these volcanoes must originate from local pockets of melt within the mantle. These pockets are thought to be heated due to tidal forces exerted by Jupiter and its neighboring moons, Europa, Ganymede and Callisto. The continued twisting and squeezing caused by these gravitational interactions produces heat, although this appears to be insufficient to maintain a completely molten layer.
Implications for exoplanetary studies
The findings extend beyond Io, influencing theories about exoplanets in orbit around M-dwarf stars. Similar to Io’s interaction with Jupiter, these exoplanets experience tidal heating. The absence of a global magma ocean on Io challenges the notion that such exoplanets would host extensive molten layers, prompting scientists to revisit these models.
