The Etosha Pan on Earth and Ontario Lacus on Titan in comparison. (c) JPL / NASA / ESA / LPG Nantes
Read Outline The outline of Lake Ontario Lacus on Saturn's moon Titan roughly resembles a footprint? as well as the Etosha pan, a mostly dry salt lake in northern Namibia. The similarities between the two lakes extend far beyond the outer shape, report researchers Thomas Cornet in the journal Icarus: Also the hydrocarbon-filled lake on Titan is in an extremely shallow pool, is partially dried and with a layer of solid particles covered by the evaporation of methane and ethane. Ontario Lacus, the largest lake in the southern hemisphere of Titan, was named after Lake Ontario in North America because they are about the same size. Otherwise, the two namesake but not much in common. The main difference: Ontario Lacus is not filled with water, but with the hydrocarbons methane, ethane and propane. Titan has developed a cycle of these substances, which is very similar to the water cycle on Earth. Cornet and his colleagues were now analyzing Ontario Lacus recordings and measurements made by the Cassini spacecraft using various instruments.

They discovered small channels in the surface both on optical images and on radar images on the southern edge of the Titan lake. So far, planetary scientists had suspected that this part of the lake is filled with liquid. But Cornet and his colleagues now assume that the lake is only about half filled. "The areas in the south are probably the permanent lake bottom, " says Cornet. Around the lake, the researchers found deposits that resembled a flood plume. This shows that the fluid level must have been higher in the past.

As the researchers write, the Etosha Pan in Namibia is the best earthly counterpart to Ontario Lacus. The barren salt lake is usually dried out, but in damp years, the groundwater level rises and fills the shallow basin of the Etosha pan a few decimeters high with water. When the liquid evaporates again, a light salt crust will be left behind. Also Ontario Lacus fills in the opinion of the researchers with Flüssigket from the soil. Since it is not about water, but about hydrocarbons, so-called alkanes, the researchers do not speak of an aquifer (in technical terms aquifer), but of an alkanofer. Instead of bright salt, however, a dark material deposits on the dried-up soil of Ontario Lacus, presumably organic substances from the atmosphere that can dissolve in the lake.

Thomas Cornet (Université de Nantes) et al .: Icarus, Vol. 218, No. 2, p. 788, doi: 10.1016 / j.icarus.2012.01.013 - Ute Kehse Anzeige


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