Enceladus ice tectonics: Cassini’s latest mind-blowing image of another world

Posted by Daniel Pendick
on Wednesday, December 17, 2008

EnceladusMany phases of the Moon ago — more than 200 — I came under the spell of earth science and wrote a lot about it for a number of years. This week, some of that ancient knowledge came back to visit as I gazed at a fantastic 28-image mosaic of Saturn’s moon Enceladus.

You may see crusty cracked ice; I see the outlines of ice continents.

At the American Geophysicial Union meeting in San Francisco this week, the halls are abuzz with talk of plate tectonics on Enceladus.

Using Cassini-based digital maps of the south polar region of Enceladus, Paul Helfenstein of Cornell University in Ithaca, New York, reconstructed a possible history of the famous “tiger stripe” features by working backward in time and progressively snipping away older and older sections of the map. Each time he found that the remaining sections fit together like puzzle pieces. Bottom line: Giant fragments of Enceldus’ crust ARE MOVING.

In the 20th century, earth scientists found evidence for plate tectonics on Earth in part by reassembling puzzle pieces of Earth’s crust delineated by cracks in the seafloor called plate boundaries.

At some boundaries, tectonic plates scrape past each other; at other boundaries, plates nose under a neighbor or crash straight into each other, raising great mountain ranges like the Himalayas.

The same process is happening on Enceladus. This implies that energy is flowing somewhere underneath all that ice — probably heat convection similar to the swirling flow ina boiling pot.

Exobiologists think that where some sort of “energy gradient” exists — a difference between warm and cool, for example — life can develop. In the 1970s, biologists stumbled on diverse ecosystems thriving at plate tectonic boundaries on the seafloor. Hot hydrothermal water and elements like sulfur were all they needed to live in the inky darkness.

Oceans of water lie beneath the crust of Encaladus. The region near its famous geysers is warmer than its surroundings — an energy gradient if ever there was one. And the geyser jets contain organic molecules.

If we could drill beneath the icy continents of Enceladus — like the pilots of the deep-sea submersible Alvin visiting hydrothermal vent ecosystems — what might we find there?

Picture thick mats of bacteria coating cracks and crevices in the hydrothermal systems in Enceldaus crust.

It’s the stuff of science fiction, but could come true in our lifetimes.

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