May 12, 2011

Jupiter’s Moon Io Contains Ocean Of Magma

NASA said on Thursday that its Galileo spacecraft has revealed a subsurface ocean of molten, or partially molten, magma beneath the surface of Jupiter's volcanic moon Io.

The research is the first direct confirmation of this kind of magma layer at Io and explains why the moon is the most volcanic object known in the solar system.

"Scientists are excited we finally understand where Io's magma is coming from and have an explanation for some of the mysterious signatures we saw in some of the Galileo's magnetic field data," Krishan Khurana, lead author of the study and former co-investigator on Galileo's magnetometer team at UCLA, said in a statement.

"It turns out Io was continually giving off a 'sounding signal' in Jupiter's rotating magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface."

Io produces about 100 times more lava every year than all the volcanoes on Earth.

Io's volcanoes are distributed all over its surface.  A global magma ocean about 20 to 30 miles beneath Io's crust helps explain the moon's activity.

"It has been suggested that both the Earth and its moon may have had similar magma oceans billions of years ago at the time of their formation, but they have long since cooled," Torrence Johnson, a former Galileo project scientist based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. said in a statement. 

"Io's volcanism informs us how volcanoes work and provides a window in time to styles of volcanic activity that may have occurred on the Earth and moon during their earliest history."

NASA's Voyager spacecraft discovered Io's volcanoes in 1979.  It is the only body in the solar system other than Earth known to have active magma volcanoes. 

"During the final phase of the Galileo mission, models of the interaction between Io and Jupiter's immense magnetic field, which bathes the moon in charged particles, were not yet sophisticated enough for us to understand what was going on in Io's interior," Xianzhe Jia, a co-author of the study at the University of Michigan, said in a statement.

NASA said the findings led Khurana and colleagues to test the hypothesis that the strange signature was produced by current flowing in a molten or partially molten layer of this kind of rock.

The space agency said the magma ocean layer on Io appears to be over 30 miles thick, making it up to at least 10 percent of the moon's mantle by volume. 

The temperature of the magma ocean probably exceeds 2,200 degrees Fahrenheit, according to NASA.


Image 1: Galileo image showing a dark spot (interrupting the red ring of short-chain sulfur allotropes deposited by Pele) produced by a major eruption at Pillan Patera in 1997. Credit: NASA/JPL/University of Arizona

Image 2: This graphic and animation show the internal structure of Jupiter's moon Io as revealed by data from NASA's Galileo spacecraft. The low-density crust about 30 to 50 kilometers (20 to 30 miles) thick is shown in gray in the cross-section. Image credit: NASA/JPL/University of Michigan/UCLA


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