[LINK] "Deep Magma Ocean Fuels Hundreds of Volcanoes on Jupiter Moon"

[rfmcdonald]

Richard Lovett at National Geographic News is one of the many sources to comment on the discovery of massive amounts of lava beneath the crust of Jupiter's innermost major moon Io.

Only slightly larger than Earth's moon, Io is the most volcanically active body in the solar system. The discovery solves a long-standing debate over how much of the moon's insides must be molten to feed the ongoing eruptions.

"At any time, Io has 400 [and] maybe more active volcanoes," said study leader Krishan Khurana, a planetary physicist at the University of California, Los Angles.

"They are very powerful—they can shoot plumes out into space to a height of about 300 miles [500 kilometers]." Finding an extensive magma ocean means that "now we know why there are so many, and where the lava comes from."

[. . .]

Khurana and colleagues made the find after reexamining readings from the Galileo spacecraft, which orbited Jupiter from 1995 to 2003 and made occasional flybys of the planet's moons, including Io.

The data showed how Io deflects Jupiter's enormous magnetic field via a process called electromagnetic induction—"very similar to the principle used by the metal detectors at the airport," Khurana said.

Magma has high electrical conductivity, he explained, a trait that laboratory studies have demonstrated with molten rocks similar to those expected to lie beneath Io's surface.

As Jupiter's electromagnetic field penetrates Io, it interacts with the magma ocean, and a current forms on the outer edge of the molten rock layer. This current in turn generates its own electromagnetic waves, which deflect Jupiter's field lines, an effect the Galileo probe was able to detect.

The data show that Io's magma exists in an underground layer that lies about [30 to 50 kilometers] beneath the surface, between the crust and the mantle.

The magma layer is at least [50 kilometers] thick, and it might be as thick as [320 kilometers].

The magma, likely with the consistency of slushy ice (a mix of molten rock and crystals), was created by tidal forces produced by Jupiter, this magma ocean in turn generating tidal energy through friction.