The linear dunes that have been observed on the surface of Saturn's largest moon, Titan, have made astronomers wonder how they came to be since day one. A number of theories on their formation was proposed, some with no merit, and others that actually stand to reason even now. To these ideas, Louisiana State University (LSU) Department of Geography and Anthropology Chair Patrick Hesp, and United States Geological Survey (USGS) scientist David Rubin recently added a new one, in a paper called “Multiple origins of linear dunes on Earth and Titan.”
The linear, or longitudinal, dunes on the surface of Titan are extremely large. In order to get a better understanding of their origin, the two scientists took to the Qaidam Basin desert, in China, where similar formations can be found today. The largest component in these dunes was, naturally, sand, but the experts discovered that the sand and silt that were also there gave the formations a more cohesive feel, and kept them together under the influence of wind.
The investigators propose that the addition of these two elements triggers a massive change in the shape of the dune itself, which moves from transverse to linear. This happens even if no noticeable changes are detected in the pattern and speed of wind blowing in a specific region. The scientists say that transversal dunes usually form under the influence of winds from a narrow directional range, whereas the longitudinal ones are created by winds from two obliquely opposing directions. Hesp and Rubin believe that this knowledge could also be applied on the surface of Titan.
The two say that, if it turns out that Titan's dunes have cohesive agents inside, then this conclusion would be in direct violation of previous studies, which hold that the sand is loose, and that the seemingly random shape of the dunes is dictated by winds coming in from alternating directions. Given the new idea, winds would blow from a single direction. In other words, if this theory turns out to be true, then everything from sand composition to Titan's wind patterns, and from the soil's density to the overall surface wetness of the satellite would have to be reassessed.