First Earth-like plate tectonics found on Jupiter’s Europa: NASA

WASHINGTON — Jupiter’s icy moon Europa may have an active system of plate tectonics, making it the first body in the Solar System other than Earth to have this type of surface- shifting geological activity, U.S. space agency NASA said Monday.

The surface of Europa — one of Jupiter’s four largest moons and slightly smaller than Earth’s moon — is riddled with cracks and ridges.

Planetary geologists Simon Kattenhorn, of the University of Idaho in Moscow, and Louise Prockter, of the Johns Hopkins University in Maryland used images taken by NASA’s Galileo orbiter in the early 2000s to reconstruct the geological history of a portion of Europa’s icy surface.

They found that nearly 20,000 square kilometers of the surface were missing in the moon’s high northern latitudes.

Further study suggested the missing terrain moved under a second surface plate — a scenario commonly seen on Earth at plate- tectonic boundaries.

Kattenhorn and Prockter saw ice volcanoes, which erupt volatiles such as water, ammonia or methane, instead of molten rock, on the overriding plate, possibly formed through melting and absorption of the slab as it dove below the surface.

They also found a lack of mountains at the so-called subduction zone, implying material was pushed into the interior rather than crumpled up as the two plates mashed against each other.

The researchers believed the subducted area was absorbed into Europa’s ice shell, which may be up to 30 kilometers thick, rather than breaking through it into Europa’s underlying ocean.

“Europa may be more Earth-like than we imagined, if it has a global plate tectonic system,” Kattenhorn said in a NASA press release. “Not only does this discovery make it one of the most geologically interesting bodies in the solar system, it also implies two-way communication between the exterior and interior — a way to move material from the surface into the ocean — a process which has significant implications for Europa’s potential as a habitable world.”

The team’s results appeared in the British journal Nature Geoscience.

In July, NASA issued an Announcement of Opportunity for proposals for science instruments that could be carried aboard a future mission to Europa.

“Europa continues to reveal itself as a dynamic world with compelling similarities to our own planet Earth,” said Curt Niebur, NASA’s outer planets program scientist. “Studying Europa addresses fundamental questions about this potentially habitable icy moon and the search for life beyond Earth.”

NASA’s Galileo spacecraft, launched in 1989, was the only space mission to make repeated visits to Europa, passing close by the moon about a dozen times. The mission officially was ended when Galileo plunged into Jupiter’s atmosphere in September 2003 to prevent an impact with Europa. (Xinhua)

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