The team combined observations from NASA’s Juno spacecraft with all available historic data, to find that volcanic activity on Jupiter’s second smallest moon is unlikely to be sourced from a magma ocean just below the surface. The findings may mean we need to rethink what we know about Io’s interior, as well as what is understood about planetary formation and evolution.
Measuring the extent of Io’s tidal deformation could help to determine whether the shallow magma ocean theory is plausible. Such measurements were taken by the Juno spacecraft in two recent flybys, and combining these observations with historic data, Ryan Park and colleagues calculate the extent to which Io is deformed by tidal forces. 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.
