Saturn's moon Titan is the most Earth-like place in our solar system, the only place other than Earth that has stable liquid on its surface. Researchers working with data collected by NASA's Cassini spacecraft, which orbits Saturn, have created the most detailed image of the Earth-like moon to-date.
By piecing together images of Titan taken by Cassini, the research team has created a mosaic that includes all of Titan's liquid hydrocarbon seas and most of its major lakes.
"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," said Steve Wall, acting radar team lead at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "While these two worlds aren't exactly the same, it shows us more and more Earth-like processes as we get new views."
Stitched together, the images reveal that Kraken Mare, Titan's largest sea, is more extensive and complex than previously believed. The images also reveal that nearly all of Titan's lakes are in an area covering 600 miles by 1,100 miles. Only 3 percent of the liquid on Titan falls outside of this area.
"Scientists have been wondering why Titan's lakes are where they are. These images show us that the bedrock and geology must be creating a particularly inviting environment for lakes in this box," said Randolph Kirk, a Cassini radar team member at the US Geological Survey in Flagstaff, Ariz. "We think it may be something like the formation of the prehistoric lake called Lake Lahontan near Lake Tahoe in Nevada and California, where deformation of the crust created fissures that could be filled up with liquid."
Ligeia Mare, Titan's second largest sea, turns out to have a very pure composition, which allowed radar signals to travel to the bottom of it, which informed scientists that the sea is about 560 feet deep.
The sea of Ligeia Mare is made mostly of liquid methane, the Cassini probe learned, providing researchers with a useful point of reference to study the moon from.
"Ligeia Mare turned out to be just the right depth for radar to detect a signal back from the sea floor, which is a signal we didn't think we'd be able to get," said Marco Mastrogiuseppe, a Cassini radar team associate at Sapienza University of Rome. "The measurement we made shows Ligeia to be deeper in at least one place than the average depth of Lake Michigan."
The researchers also calculated that there are about 2,000 cubic miles (9,000 cubic kilometers) of liquid hydrocarbons on Titan, about 40 times more than all of the proven oil reserves on Earth.