The Mystery of Titan's Sand Dunes: Winds are Powerful on Saturn's Moon

Saturn's largest moon, Titan, is an unusual world. Unlike other moons, it has a dense atmosphere, and even has rivers and lakes made up of components of natural gas. Now, scientists have taken a closer look at one of its other unusual features, its dunes, and have found that winds must blow far faster and more violently than previously thought.

The windswept dunes on Titan are hundreds of yards high, more than a mile wide and hundreds of miles long. With dunes like these, it's obvious that windy forces are at work. Yet until about a decade ago, researchers didn't know these dunes even existed. It was only when the Cassini spacecraft snapped pictures of Titan that the scientists saw the dunes that were created by particles that they didn't know existed.

"It was surprising that Titan had particles the size of grains of sand-we still don't understand their source-and that it had winds strong enough to move them," said Devon Burr, one of the researchers, in a news release. "Before seeing the images, we thought the winds were likely too light to accomplish this movement."

While the Cassini data showed that the predominant winds blew from east to west, though, the streamlined appearance around mountains and craters seemed to show that they were created by winds moving in the opposite direction.

The scientists created a wind tunnel to recreate Titan's surface conditions to get to the bottom of the mystery. They used 23 varieties of sand in the wind tunnel in order to capture the possible sand behavior. In the end, they found that the minimum wind on Titan must be 50 percent faster than previously thought. In addition, the higher wind speed offers an explanation for the shape of the dunes.

"If the predominant winds are light and blow east to west, then they are not strong enough to move sand," said Burr. "But a rare event may case winds to reverse momentarily and strengthen."

The findings reveal a bit more about the conditions on Titan, and show exactly how its strange dunes formed.

The findings are published in the journal Nature.

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