Io’s Missing Magma Ocean
In the late 1970s, scientists conjectured that Io was likely a volcanic world, heated by tidal forces from Jupiter that squeeze it along its elliptical orbit. Only months later, images from Voyager 1’s flyby confirmed the moon’s volcanism. Magnetometer data from Galileo’s later flyby suggested that tidal heating had created a shallow magma ocean that powered the moon’s volcanic activity. But newly analyzed data from Juno’s flyby shows that Io doesn’t have a magma ocean after all.
The new flyby used radio transmission data to measure any little wobbles that Io caused by tugging Juno off its expected course. The team expected a magma ocean to cause plenty of distortions for the spacecraft, but the effect was much slighter than expected. Their conclusion? Io has no magma ocean lurking under its crust. The results don’t preclude a deeper magma ocean, but at what point do you distinguish a magma ocean from a body’s liquid core?
Instead, scientists are now exploring the possibility that Io’s magma shoots up from much smaller pockets of magma rather than one enormous, shared source. (Image credit: NASA/JPL/USGS; research credit: R. Park et al.; see also Quanta)
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