Sinkholes on Titan? Unlocking origins of lakes on Saturn's largest moon
Scientists may be starting to understand the origins of the mysterious lakes on Saturn鈥檚 moon Titan.
Titan鈥檚 surface is home to depressions filled with liquid hydrocarbons, much like seas and lakes on Earth. Those depressions, , are formed through a process similar to the creation of caves and sinkholes on Earth.
鈥淲e compared the erosion rates of organics in liquid hydrocarbons on Titan with those of carbonate and evaporite minerals in liquid water on Earth,鈥� the European Space Agency鈥檚 (ESA) Thomas Cornet in a statement.
鈥淲e found that the dissolution process occurs on Titan some 30 times slower than on Earth due to the longer length of Titan鈥檚 year and the fact it only rains during Titan summer,鈥� Mr. Cornet added. 鈥淣onetheless, we believe that dissolution is a major cause of landscape evolution on Titan and could be the origin of its lakes.鈥�
Besides Earth, Titan is the only body in the solar system known to have surface lakes and seas, according to data collected by the joint NASA and ESA mission, .
These and other similarities have led many planetary scientists to view Titan as a kind of time capsule, one that shows what conditions on earth might have been like before life emerged, 海角大神鈥檚 Pete Spotts noted.
鈥淭hough Earth is much warmer than Titan, the moon hosts an inventory of organic compounds thought to be similar to those on Earth before life took hold,鈥� he wrote. 鈥淎nd the processes shaping Titan's surface 鈥� from flowing liquids to volcanic action 鈥� mirror those of Earth.鈥�
The new study, published in the Journal of Geophysical Research: Planets in May, provides further support for comparing Titan and our planet. Though the moon鈥檚 icy surface temperatures 鈥� roughly minus 292 degrees Fahrenheit 鈥� means that liquid methane and ethane, not water, dominate its surface, Cornet and his team found that Titan鈥檚 lakes resemble Earth鈥檚 caves, sinkholes, and sinking streams.
These Earthly features, known as karstic landforms, result from erosion of dissolvable rocks, such as limestone and gypsum, in groundwater and rainfall. How fast the rocks erode depends on factors such as humidity, rainfall, and surface temperature. The scientists, assuming that Titan鈥檚 surface is covered in solid organic material and that the main dissolving agent is liquid hydrocarbons, calculated how long it would take for parts of Titan鈥檚 surface to create these features.
The resulting time frame shows it takes about 50 million years to create a 300-foot depression at Titan's relatively rainy polar regions, consistent with the youthful age of the moon's surface. In the moon鈥檚 less rainy areas, the timescale is much longer: about 375 million years.
Cornet acknowledged some uncertainties with the calculations, but noted that the figures are consistent with Titan鈥檚 relatively youthful billion-year-old surface.
And despite the differences between Titan and Earth, the geological process that leads to the lakes鈥� formation looks surprisingly similar.
鈥淏y comparing Titan鈥檚 surface features with examples on Earth and applying a few simple calculations, we have found similar land-shaping processes that could be operating under very different climate and chemical regimes,鈥� said Nicolas Altobelli, ESA's Cassini project scientist.
鈥淭his is a great comparative study between our home planet and a dynamic world more than a billion kilometers away in the outer solar system,鈥� he added.
