Building Titan's Dunes

When the Cassini spacecraft returned pictures of the surface of Saturn's moon Titan a decade ago, researchers were startled by the band of towering dunes that ran around its equator. Scientists immediately began to puzzle out what these dunes might be made of, and how they might have been formed. Now, Dr. Devon Burr, from the Department of Earth and Planetary Sciences at the University of Tennessee in Knoxville, and her colleagues, have worked out some explanation. They repeated painstaking experiments in a sealed wind-tunnel to simulate Titan's thick atmosphere. Their results suggest that the dunes are probably not made of sand as we understand it, but of super-light and super-cold particles of ice and organics, like methane. And even in Titan's low gravity, it probably takes stronger winds than we thought might circulate there to pile them into 100-meter-tall dunes.