By Xinhua
Beijing : vast ocean of water and ammonia may lurk deep beneath the surface of Titan, the intriguing, orange moon of Saturn already known for its blanket of clouds and dense atmosphere, according to scientists.
Astronomers have not directly observed this ocean. However, they said on Thursday that observations made by the Cassini spacecraft of Titan’s rotation and shifts in the location of surface features suggest an ocean exists perhaps 100 kilometers below the surface.
Titan is Saturn’s largest moon and the second biggest in the solar system, only slightly smaller than Jupiter’s moon Ganymede. Titan’s diameter of about 5,150km is larger than the planet Mercury and the dwarf planet Pluto.
Cassini, exploring Saturn and its moons in an ongoing US-European mission, collected measurements using radar that penetrated Titan’s thick clouds during 19 passes over the moon from October 2005 to May 2007.
Data from the early observations allowed researchers to establish the locations of 50 landmarks including lakes, canyons and mountains on Titan’s surface. They looked at later radar data and discovered that prominent surface features had shifted location by up to 30km.
The spin of Titan’s crust is linked to winds blowing through its atmosphere, the scientists said. But the type of broad displacement of surface features seen on Titan would be hard to explain unless its crust were separated from its core by an internal ocean, allowing the crust essentially to float.
“It’s because Titan’s crust seems to be so mobile that we infer this internal ocean,” said Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who directed the research published in the journal Science.