Sculpting the dunes on Saturn's largest moon Titan took 88,000 Earth years, or 3,000 years in Saturn time, new analysis of images taken by NASA's Cassini spacecraft shows.
The study, which appears in this week's Nature Geoscience, points to long-term climate cycles, tied to variations in Saturn's orbit, as the key mechanism for creating Titan's dunes.
PHOTO: Cassini Spies Titan's Undulating Dunes
Titan is only the fourth place in the solar system known to have wind-blown dunes on its surface. The others are Earth, Venus and Mars.
Titan's "sand" is believed to be small particles of solid hydrocarbons, or ice-wrapped hydrocarbons, that are about one-third as dense as sand on Earth.
Related research published in this week's Nature shows that current computer models sorely underestimate the wind speed needed to move sand and form the dunes on Titan. Scientists using a wind tunnel at Arizona State University figured Titan's dune-forming winds are 40 percent to 50 percent higher than previous predictions.
"Dunes begin to form when the wind picks up loose particles from the ground and drives them to hop ... downwind. A key part of understanding dunes is to identify the threshold wind speed that causes dune particles to start to move," Arizona State University wrote in a press release about the research.
ANALYSIS: Titan's Great Dune Seas Rival Science Fiction Worlds
The experiments show that Titan's sand needs winds of at least 3.2 mph to lift. On Earth, that's a very light breeze, but Titan's gravity is about one-seventh as strong as Earth's and the particles weigh only about 4 percent as much as terrestrial sand.
"This is a dense atmosphere blowing against particles that are very light," co-author Nathan Bridges, with Johns Hopkins University Applied Physics Laboratory, said in the press release.
Weak, everyday winds, which on Titan blow from the east, would have little if any impact on lifting sand from the surface, the researchers conclude. Rather, it is the occasional strong westerly wind that launches the dunes into action.