Lakes discovered on the surface of Saturn's mighty moon Titan could, in fact, be sinkholes created by a process or erosion driven by precipitation. If true, this process would mimic one seen on our own home planet.

Hydrocarbon lakes on Saturn's giant satellite were first seen in radar images recorded by the Cassini spacecraft orbiting the planet Saturn. New data from Cassini shows the lakes may have been created as the surface collapses, forming sinkholes that then fill with liquid hydrocarbons, including ethane and methane.

Two types of depressions have been identified on the surface of Titan. The first of these are filled with hydrocarbons and are connected to each other, creating a network of lakes and channels. Other basins are dry and are not connected to one another. Since they were first discovered, astronomers have questioned how these features came to be on the surface of the second-largest moon in the Solar System.

Karstic landforms form on Earth through the actions of rainfall and groundwater on dissolvable rock, resulting in sinkholes, occasionally swallowing homes and vehicles and destroying roadways. Astronomers studying the mysterious basins on Titan believe a similar process may be taking place on the distant moon. Calculations suggest that a basin 300 feet in diameter could form in the polar regions of Titan in around 50 million years through this process.

"We compared the erosion rates of organics in liquid hydrocarbons on Titan with those of carbonate and evaporite minerals in liquid water on Earth. We found that the dissolution process occurs on Titan some 30 times slower than on Earth due to the longer length of Titan's year and the fact it only rains during Titan summer," Thomas Cornet of the European Space Agency said.

Despite the fact that the formation of such sinkholes would take so much longer to form on Titan than on Earth, many researchers now believe the process could be taking place on the Saturnian satellite. The time estimate assumed the surface is completely covered in pure organic materials and that the primary dissolving agents are hydrocarbons. The best-known data concerning the climate of the massive satellite was utilized in the development of the model.  

Researchers calculated how long it would take for such depressions to form at lower latitudes, where hydrocarbon precipitation is not as common as it is near the poles. The model revealed such basins would take around 375 million years to form closer to the equator. This could explain the relative scarcity of such features at lower latitudes, investigators concluded.

The Cassini spacecraft is a joint mission of NASA, the European Space Agency (ESA) and the Italian Space Agency.

Analysis of the possible Karstic landforms on Titan was published in the Journal of Geophysical Research, Planets.