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Geological activity on a frozen world

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Staff writer ▼ | August 9, 2008
The new images sent from the Cassini spacecraft passing by Enceladus revealed plumes of water-ice jetting out into space. That opens new questions about life on Jupiter's moon.
Simon Kattenhorn
Simon KattenhornThe new images sent from the Cassini spacecraft passing by Enceladus revealed plumes of water-ice jetting out into space. That opens new questions about life on Jupiter's moon.

With average temperatures of minus 260 degrees Fahrenheit, an almost nonexistent atmosphere and a complex web of cracks in a layer of ice encompassing the entire surface, the environment on Jupiter’s moon Europa is as alien as it can be. So are the enormous forces behind the surface display, namely an ocean beneath the ice nine times deeper than Earth’s deepest ocean trench and gravitational affects from a planet 318 times the mass of Earth.

For nearly a decade, it has been Simon Kattenhorn's passion to understand the amazing surface features on Europa and how they are formed. And supported by new grants from NASA, his research may provide clues to one of mankind's biggest questions – is there life outside of Earth?

Mr. Kattenhorn is an associate professor of geology at the University of Idaho. The first of his two recent grants totaling 358,000 dollars will allow him to study the most recent geological features on the highest resolution photos NASA has to offer of Europa. These subtle cracks will reveal if there is any current geological activity on the distant moon, which also would be the best place to look for signs of life.

Simon Kattenhorn“In the case of Europa, the best place to look is where cracks on its icy surface are active today,” said Kattenhorn, who also is currently authoring a chapter for a book on the moon. But finding signs for current geological activity is no easy task.

Kattenhorn can tell a lot about fractures because they form very specific patterns that allow him to unravel their relative ages. His goal in this project is to find the youngest fractures and compare them to the tidal forces that Europa would be experiencing today to see if the features and recent forces match up.

There is some debate over how thick Europa’s outer shell of ice is – some say more than 20 miles and some claim only a few – but it is generally agreed that it covers an ocean more than 60 miles deep. This means that although Europa is only about the size of our moon, it has more water than Earth.

As the moon orbits Jupiter, it gets closer and further from the giant planet, changing the amount of gravitational pull it experiences. The result is that the moon is constantly being squeezed and released like a balloon full of water, which causes cracks and fissures, raising the question of the possibility of geysers, like the ones recently spotted on Saturn's moon Enceladus.

Recent photos from the Cassini spacecraft passing by Enceladus revealed stunning plumes of water-ice jetting out into space. The discovery sent a flurry of excitement and activity through the academic community, including Kattenhorn, whose second recent NASA grant will allow him to apply what he’s learned from Europa to studies on Enceladus.

The discovery also led to a renewed vigour to study and explore Europa to find out if similar, active processes might be occurring today. “This research feeds that need that I have as a geologist and as a person to be the explorer, to be the adventurer, to see things that no one else has seen before and figure out things that no one else has figured out before,” said Kattenhorn of his research into the two moons.

“And out in the solar system is a great place to do that, because there are some things – like the plumes on Enceladus – that we really are seeing for the very first time.”

Recent discoveries of amazingly adaptive bacteria in some of Earth’s harshest environments have led to the speculation that it is possible. “Europa has the potential for something very similar to hydrothermal systems we have here in our oceans,” said Susan Childers, head of the geomicrobiology research team at the University of Idaho, who studies life in extreme environments.

“Very ancient organisms that thrive on oxidized metals potentially could be centered on one of these oases formed by heat and metals seeping from cracks in the ocean floor," says Mr. Kattenhorn in release published on the website of University of Idaho.