Cassini spots hydrocarbon lakes on Saturn's moon Titan

Using its radar system, the Cassini spacecraft had discovered very strong evidence for the existence of lakes on Saturn's moon Titan, scientists with U.S. space agency NASA reported on Monday.

The lakes appeared to be filled with hydrocarbon liquids, possibly making Titan the only place other than Earth known to contain lakes, said scientists at NASA's Jet Propulsion Laboratory based in Pasadena, California.

Dark patches, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan's north pole. Scientists have speculated that liquid methane or ethane might form lakes on Titan, particularly near the somewhat colder polar regions.

During its latest flyby on July 21, 2006, the Cassini radar instrument acquired two images in synthetic aperture mode. The images, each covering about 60,000 square kilometers, have shown details of a dozen lakes, some up to 100 kilometers wide, the scientists said.

In the images, the lakes appeared to be a variety of dark patches, some with channels leading in or out of them. The channels have a shape that strongly implies they were carved by liquid.

Some of the dark patches and connecting channels are completely black, that is, they reflect back essentially no radar signal, and hence must be extremely smooth. In some cases rims can be seen around the dark patches, suggesting deposits that might form as liquid evaporates.

The abundant methane in Titan's atmosphere is stable as a liquid under Titan's conditions, as is its abundant chemical product, ethane, but liquid water is not.

"For all these reasons, scientists interpret the dark areas as lakes of liquid methane or ethane, making Titan the only body in the solar system besides Earth known to possess lakes," the Jet Propulsion Laboratory said.

Source: Xinhua