Differences Fall Away Like Sand on Titan

New research looks at ooids on Earth to model how grains of sediment made of hydrocarbon sand could form and last on the surface of Titan.

IMAGE: These three mosaics of Titan were composed with data from Cassini’s visual and infrared mapping spectrometer taken during the last three Titan flybys, on Oct. 28, 2005 (left), Dec. 26, 2005 (middle), and Jan. 15, 2006 (right). In a new study, researchers have shown how Titan’s distinct dunes, plains, and labyrinth terrains could be formed. CREDIT: NASA / JPL / University of Arizona

New research published in Geophysical Research Letters and led by Mathieu Lapôtre models just how grains of sediment could form and exist on the large moon. On Earth, our sediment consists primarily of silicate rocks and minerals, which erode down into grains over very long periods of time. Silica is pretty hardy, after all, and doesn’t break down easily, so it takes erosion by wind and water to produce sand.

However, hydrocarbons are organic compounds, and they are more fragile than silicate grains, which means they should become dust over time. Lapôtre explains: As winds transport grains, the grains collide with each other and with the surface. These collisions tend to decrease grain size through time. What we were missing was the growth mechanism that could counterbalance that and enable sand grains to maintain a stable size through time.

To reconcile this mystery, the team turned to ooids on Earth, which are found in shallow tropical seas. Ooids are small, spherical grains made when calcium carbonate is removed from the water column and attaches to a silica grain, like quartz. The carbonate…