The radar imaging system detected more than 75 dark patches in the landscape near Titan’s northern polar region, the scientists said in a detailed description of the find published today in the journal Nature.
The patches, they said, indicated smooth surfaces in an otherwise rugged topography, suggesting lake beds either partly dry or filled with liquid. These smooth surfaces, more or less circular and with diameters ranging from 2 miles to 40 miles, are associated with channels that appear to have been formed by flowing liquids, presumably tributaries to the lakes.
Methane exists in Titan’s atmosphere and, in the extreme cold of high latitudes, is expected to rain on the surface and be present as liquids in subsurface reservoirs.
The radar images, made on a close pass of Saturn’s largest moon by the Cassini spacecraft in July, “provide definitive evidence for the presence of lakes on the surface of Titan,” the discovery team concluded.
When the spacecraft conducted its first radar search above 70 degrees north latitude, Ellen R. Stofan, leader of the team, said in an interview, “We saw a huge swath of the surface just covered with lakes, like Minnesota.”