NASA's Cassini spacecraft has found evidence of the long-sought seas of Titan, planetary scientists announced this week.
Several instruments aboard the craft, which has been orbiting Saturn and its largest moon for the past two years, have identified large, dark features at the moon's north polar region. The new areas are flat and undifferentiated, several hundred miles across and have sharp, shoreline-type features.
Cassini scientists said the latest images are still short of "smoking gun" proof, but represent the best evidence so far that there are large bodies of liquid, probably methane and ethane, on the surface of the solar system's second-largest moon.
Large seas "are the simplest explanation that fits the data we've seen so far," said Jonathan Lunine, an astronomer and Cassini scientist at the University of Arizona.
Scientists have been looking for seas or oceans of methane on Titan since NASA's Voyager mission 25 years ago found evidence of a smog-choked atmosphere around the moon. There must be some source for the hydrocarbon muck surrounding Titan, they theorized, or else the atmosphere would have disappeared billions of years ago.
Scientists originally speculated that there must be a global ocean of methane. But Cassini and its Huygens probe, which landed on the surface of the moon, found nothing resembling large bodies of liquid.
In recent weeks, however, Cassini focused its radar and infrared mapping instruments on Titan's north pole region. Vast dark regions started unfolding. One of the spacecraft's cameras also found a large, irregular dark feature corresponding to the radar image.
The largest possible body of liquid is being compared to the Caspian Sea, Earth's largest lake with an area of 143,000 square miles.
Los Angeles Times