Titan may have lakes, rivers

DARMSTADT, Germany — It is a desperately cold, forbidding landscape, but scientists said yesterday that Saturn's moon Titan may have one thing found nowhere else in the solar system besides Earth: lakes and rivers.

"I'm just staggered by the level of detail," said European Space Agency science chief David Southwood, examining images of Titan captured by the agency's Huygens space probe on Friday.

Southwood was one of scores of exhausted but exultant scientists who took a first look at the near-flawless data returned by Huygens as it parachuted 789 miles through Titan's smoggy atmosphere and came to rest on a rock-strewn plain bathed in orange twilight, with a spongy surface topped by a thin crust.

"The closest analogues are wet sand or clay," said John Zarnecki, in charge of instruments analyzing Titan's surface.

The imaging team presented its first panoramic view of Titan's surface yesterday, showing a broad expanse of what looked like coastline, crags and glacier-like deposits.

"It's almost impossible to resist the interpretation that this is some kind of drainage channel," imaging-team leader Marty Tomasko told reporters, pointing to a gorge running through the middle of the picture. But, he said, "you have to be careful, because we're biased by the things we see on Earth." The "sea" in the panorama may not be liquid, but instead a mushy hydrocarbon slush.

An early-Friday photo suggesting a treacly lava flow fit neatly into yesterday's panorama, suggesting a glacier-like wall of sludge moving toward the "coastline." A white band framing the junction of coast and ocean could indicate some sort of "ground fog," Tomasko said.

All of this suggested that Titan's surface is a shifting, oozing combination of gravel, stones, hydrocarbon sludge and, possibly, ethane lakes or ponds.

"There's weather," Southwood said. "It's unlike any other place except Earth." There was no lightning or thunder, as Huygens' microphone picked up little but white noise.

All six of Huygens' instruments functioned perfectly, and although a software glitch stymied transmission of data about Titan's winds, 18 Earth-based radio telescopes on four continents were able to eavesdrop on the probe's signals and will collaborate to reproduce the experiment.

Scientists have long coveted the opportunity to see Titan up close, but until now they have been frustrated by a cloud of methane-laced nitrogen that obscures its surface.

Scientists believe that Titan's atmosphere may be similar to that of primordial Earth and that studying it could provide clues to how life began on our planet.

Forcing Titan to surrender its secrets was a principal goal when NASA and the European and Italian space agencies launched the Cassini-Huygens spacecraft in 1997 on a voyage of exploration to Saturn, its rings and seven of its 33 known moons.

The methane haze, which gives Titan a green-blue cast at higher altitudes, turns the sky bright orange at ground level, spectrographic data taken by Huygens showed. Surface temperatures were 291 degrees below zero Fahrenheit.

Material from The Associated Press