Cassini Reveals Earth-like Land on Titan

These radar images, from a strip more than 2,796 miles long, show Xanadu is surrounded by darker terrain, reminiscent of a free-standing landmass. At the region's western edge, dark sand dunes give way to land cut by river networks, hills and valleys. These narrow river networks flow onto darker areas, which may be lakes. A crater formed by the impact of an asteroid or by water volcanism is also visible. More channels snake through the eastern part of Xanadu, ending on a dark plain where dunes, abundant elsewhere, seem absent. Appalachian-sized mountains crisscross the region.

"We could only speculate about the nature of this mysterious bright country, too far from us for details to be revealed by Earth-based and space-based telescopes. Now, under Cassini's powerful radar eyes, facts are replacing speculation," said Jonathan Lunine, Cassini interdisciplinary scientist at the University of Arizona, Tucson. "Surprisingly, this cold, faraway region has geological features remarkably like Earth."

Titan is a place of twilight, dimmed by a haze of hydrocarbons surrounding it. Cassini's radar instrument can see through the haze by bouncing radio signals off the surface and timing their return. In the radar images bright regions indicate rough or scattering material, while a dark region might be smoother or more absorbing material, possibly liquid.

Xanadu was first discovered by NASA's Hubble Space Telescope in 1994 as a striking bright spot seen in infrared imaging. When Cassini's radar system viewed Xanadu on April 30, 2006, it found a surface modified by winds, rain, and the flow of liquids. At Titan's frigid temperatures, the liquid cannot be water; it is almost certainly methane or ethane.

"Although Titan gets far less sunlight and is much smaller and colder than Earth, Xanadu is no longer just a mere bright spot, but a land where rivers flow down to a sunless sea," Lunine said.

Observations by the European Space Agency's Huygens probe, that Cassini carried to Titan, and by NASA's Voyager spacecraft strongly hint that both methane rain and dark orange hydrocarbon solids fall like soot from the moon's dark skies.

On Xanadu, liquid methane might fall as rain or trickle from springs. Rivers of methane might carve the channels and carry off grains of material to accumulate as sand dunes elsewhere on Titan.

"This land is heavily tortured, convoluted and filled with hills and mountains," said Steve Wall, the Cassini radar team's deputy leader at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "There appear to be faults, deeply cut channels and valleys. Also, it appears to be the only vast area not covered by organic dirt. Xanadu has been washed clean. What is left underneath looks like very porous water ice, maybe filled with caverns.

"In the 1980s, it took the shuttle imaging radar to discover subsurface rivers in the Sahara. Similarly, if it hadn't been for the Cassini radar, we would have missed all of this. We have a newly discovered continent to explore," Wall said.

Cassini will view Titan again on Saturday, July 22, exploring the high northern latitudes. In the next two years the orbiter will fly by Titan 29 times, nearly twice as many encounters as in the first half of Cassini's four-year prime mission. Twelve of the planned flybys will use radar.

Source: NASA

Titan's Enigmatic Infrared-Bright Spot Is Surface Make-Up
A 300-mile-wide patch that outshines everything else on Titan at long infrared wavelengths appears not to be a mountain, a cloud or a geologically active hot spot, University of Arizona scientists and Cassini team members say.

Odd spot on Titan baffles scientists
Saturn's moon Titan shows an unusual bright spot that has scientists mystified. The spot, approximately the size and shape of West Virginia, is just southeast of the bright region called Xanadu and is visible to multiple instruments on the Cassini spacecraft.
The 483-kilometer-wide (300-mile) region may be a "hot" spot -- an area possibly warmed by a recent asteroid impact or by a mixture of water ice and ammonia from a warm interior, oozing out of an ice volcano onto colder surrounding terrain. Other possibilities for the unusual bright spot include landscape features holding clouds in place or unusual materials on the surface.
Titan still offers all possibilities for the Huygens probe landing
The prospect of the Huygens probe landing on a hard, soft or liquid surface when it lands on Titan on Friday still remain following further analysis of data taken during the Cassini mother ship's closest encounter with Saturn's largest moon.
Cassini instrument confirms liquid surface lake on Titan
Scientists have confirmed that at least one body in our solar system, other than Earth, has a surface liquid lake. Using an instrument on NASA's Cassini orbiter, they discovered that a lake-like feature in the south polar region of Saturn's moon, Titan, is truly wet. The lake is about 235 kilometers, or 150 miles, long.
Saturn images to be displayed in New York
The National Aeronautics and Space Administration says some of the best images from Saturn and the planet's rings and moons will be displayed in New York.
Mars radar opens up a planet’s third dimension
ESA’s Mars Express radar sounder, MARSIS, has looked beneath the martian surface and opened up the third dimension for planetary exploration. The technique’s success is prompting scientists to think of all the other places in the Solar System where they would like to use radar sounders.
NASA Extends Cassini's Grand Tour of Saturn
NASA is extending the international Cassini-Huygens mission by two years. The historic spacecraft's stunning discoveries and images have revolutionized our knowledge of Saturn and its moons.
Ocean May Exist Beneath Titan's Crust
NASA's Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan. The findings made using radar measurements of Titan's rotation will appear in the March 21 issue of the journal Science.

Cassini Reveals Earth-like Land on Titan

Related stories:

News discussion: