April 21, 2012
Lake On Titan Resembles One In Africa
A new study based on data from the Cassini spacecraft suggests that a lake on one of Saturn's moons behaves similarly to the Etosha salt pan on Earth.
A group led by Thomas Cornet of the UniversitÃ© de Nantes, France, a Cassini associate, found characteristics of Ontario Lake on Titan are similar to Etosha Pan in Namibia, Africa because it drains and refills from below.
Etosha Pan is a lake bed that fills with a shallow layer of water from groundwater levels that rise during the rainy season. This layer evaporates, leaving behind sediments like tide marks, showing the previous dimensions of the water.
The team found evidence for long-standing channels etched into the Titan lake bed within the southern boundary of the depression.
"We conclude that the solid floor of Ontario Lacus is most probably exposed in those areas," Cornet, whose paper appears in a recent issue of the journal Icarus, said.
Bonnie Buratti, a co-author and Cassini team member, said that salt pans on Earth form in deserts where liquids can suddenly accumulate. She said this appears to be the same thing happening on Titan.
One of the differences between the lake on Titan compared to the one in Africa is that Ontario Lacus is methane, ethane and propane, not water. However, the cycle, NASA said, appears to work in a very similar fashion to the water cycle on Earth.
Titan is the only place other than Earth that is known to have stable liquid on its surface. The full hydrocarbon cycle on Titan is based on hydrogen, carbon and nitrogen, and is based on the moon's atmosphere.
NASA said Cassini has been observing the lake with multiple instruments and employing several methods to help determine if Titan changes with the seasons. Through use of these instruments, Cassini was able to witness Titan's southern hemisphere transition from summer to fall.
"These results emphasize the importance of comparative planetology in modern planetary sciences: finding familiar geological features on alien worlds like Titan allows us to test the theories explaining their formation," Nicolas Altobelli, ESA's Cassini-Huygens project scientist, said in a press release.
The team combined data from Cassini's imaging, spectroscopic and radar instruments to make their finding.
The channels the scientists found etched into the lake bed remained visible between December 2007 and January 2010.
Image 1: A recent study finds that the lake known as Ontario Lacus on Saturn's moon Titan (left) bears striking similarity to a salt pan on Earth known as the Etosha Pan (right). Image credit: NASA/JPL-Caltech and NASA/USGS
Image 2: Ontario Lacus is Titan's largest lake in its southern hemisphere. It is an ephemeral lake that resembles Etosha Pan in Namibia, Africa. On Titan the liquid is made of hydrocarbons, whereas on Earth it is made of water. Credit: Cassini radar image: JPL/NASA. Envisat radar image: ESA. Composite image: LPGNantes