Icy Europa is on the short list of places where extraterrestrial life might exist. Jupiter’s moon, which is slightly smaller than our own, is believed to contain 3 times more liquid water than the Earth. Now new research is suggesting that it may also experience plate tectonics of the type that causes earthquakes and creates mountain ranges. Results of a recent geological survey show that a 12,000 square mile chunk of Europa’s surface, photographed by NASA’s Galileo spacecraft is missing. Researchers theorize that the area may have been pushed beneath the surface by shifting geological plates.

Plate tectonics are a large part of what makes Earth unique. The rest of the planets in the universe appear to have a solid crust. The Earth’s crust, the upper part of the mantle, is broken into late pieces which move at an almost imperceptible rate of just a few inches per year. This tiny movement is what has pushed the Earth’s continents apart, through a process called continental drift. When these plates rub together it causes instability such as earthquakes and volcanoes. Over time plates can continue to push into each other, or one plate can be pushed beneath another causing depressions and mountain ranges.

Researchers have long had evidence of Europa’s crust expanding, but hand’t found areas where old crust was destroyed to allow for new crust. However, while exploring Galileo images from the Early 2000’s planetary geologists Simon Kattenhorn, of the University of Idaho, Moscow, and Louise Prockter, of the Johns Hopkins University Applied Physics Laboratory discovered unusual geological boundaries.

“We have been puzzled for years as to how all this new terrain could be formed, but we couldn’t figure out how it was accommodated. We finally think we’ve found the answer,” said Prockter in a statement.

When studying Europa, scientists frequently reconstruct the surface blocks of the moon into their original configuration to create a picture of what the surface looked like prior to a disruption. However, when Kattenhorn and Prockter did this they found that they had a large piece of the jigsaw puzzle left over.

Further examination suggested that the 12,000 mile piece of crust had moved under a second geographic plate. The researchers observed ice volcanos on the new plate, which could have been caused by the melting and absorption of the original plate as it was driven beneath the surface. The area also lacked the mountains which would form of the two plates continually pushed into one another.

“Europa may be more Earth-like than we imagined, if it has a global plate tectonic system. 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,” said Kattenhorn.

In July of this year, NASA issued an Announcement of Opportunity for proposals for science instruments to be carried on a future mission to Europa. This new evidence of plate tectonics greatly expands the number of things that scientists may wish to measure and explore and expands speculation about some form of life on the small, icy but very Earth-like moon.

The team’s research appears in the online edition of the journal Nature Geoscience.