By now you probably know about the lakes of liquid hydrocarbons on Titan. Thanks to Cassini, we know that Saturn’s largest moon is the one other place in the solar system where liquid can be found in stable amounts on the surface, except that it’s not water like we have here on Earth, but rather liquid methane. (Thank you for not smoking!) Now, radar measurements by Cassini show that Titan’s lakes are nearly all found in one 600 x 1100-mile region around its north pole — a true “land o’lakes!”
The animation above, made up of colorized radar data acquired over the past 9 years that the spacecraft has been in orbit around Saturn, takes us on a flyover tour of Titan’s northern lakes region. Fasten your seat belts!
In the projection below Titan’s north pole is at the center. The view extends down to 50 degrees north latitude. In this color scheme, liquids appear blue and black depending on the way the radar bounced off the surface. Land areas appear yellow to white. A haze was added to simulate the Titan atmosphere.
Kraken Mare, Titan’s largest sea, is the body in black and blue that sprawls from just below and to the right of the north pole down to the bottom right. Ligeia Mare, Titan’s second largest sea, is a nearly heart-shaped body to the left and above the north pole. Punga Mare is just below the north pole.
A creative application of a method previously used to analyze data at Mars also revealed that Ligeia Mare is about 560 feet (170 meters) deep. This is the first time scientists have been able to plumb the bottom of a lake or sea on Titan. This was possible partly because the liquid turned out to be very pure, allowing the radar signal to pass through it easily. The liquid surface may be as smooth as the paint on our cars, and it is very clear to radar eyes.
The area above and to the left of the north pole is dotted with smaller lakes. Lakes in this area are about 30 miles (50 kilometers) across or less.
Most of the bodies of liquid on Titan occur in the northern hemisphere. In fact nearly all the lakes and seas on Titan fall into a box covering about 600 by 1,100 miles (900 by 1,800 kilometers). Only 3 percent of the liquid at Titan falls outside of this area.
Scientists are trying to identify the geologic processes that are creating large depressions capable of holding major seas in this limited area. A prime suspect is regional extension of the crust, which on Earth leads to the formation of faults creating alternating basins and roughly parallel mountain ranges. This process has shaped the Basin and Range province of the western United States, and during the period of cooler climate 13,000 years ago much of the present state of Nevada was flooded with Lake Lahontan, which (though smaller) bears a strong resemblance to the region of closely packed seas on Titan.
“Learning about surface features like lakes and seas helps us to understand how Titan’s liquids, solids and gases interact to make it so Earth-like. While these two worlds aren’t exactly the same, it shows us more and more Earth-like processes as we get new views.”
– Steve Wall, acting radar team lead at NASA’s Jet Propulsion Laboratory