Probe gets first look at mysterious Titan


As elated scientists gasped in delight, a spunky, wok-shaped European space probe called Huygens beamed home yesterday the first images from the smog-shrouded surface of Saturn's moon Titan - widely considered the most inscrutable spot in the solar system.

The first black-and-white images, snapped during the probe's 2 1/2 -hour parachute descent, revealed a landscape etched with what appeared to be fluid-cut channels snaking toward the shoreline of a liquid methane lake.

If those impressions are accurate, it would mark the first time that scientists have run across liquid formations anywhere but Earth.

Huygens' successful landing, after a journey of almost seven years, marked the first time a spacecraft has touched down on the moon of another planet - and the first fresh images of the surface of another world since Viking 1 landed on Mars in 1976.

"The scientific data that we are collecting now shall unveil the secrets of this new world," declared Jean-Jacques Dordain, director general of the European Space Agency, which orchestrated the mission in partnership with NASA and the Italian space agency.

Emotion-choked scientists and engineers at ESA's control center in Darmstadt, Germany, broke into hearty applause - and others shed tears - as the first data from the Huygens spacecraft began to flash up on their screens around 11:20 a.m. Eastern time.

In all, scientists said they received more than three hours of data from the probe's six onboard instruments, including at least 10 precious minutes of measurements from Titan's surface.

"This data is data for posterity," David Southwood, ESA's director of science, said during a packed news conference yesterday. "I don't think it's likely in the lifetime of anyone in this room that we will repeat a landing on Titan."

Since its discovery in 1655 by Dutch astronomer Christiaan Huygens, the moon has been an irresistible - if frustrating - scientific target. With a diameter between that of Mercury and Mars, Titan is more planet than moon. It's also one of only four solid bodies in the solar system with a substantial atmosphere. The others are Venus, Mars and Earth.

And it's not just any atmosphere. Composed mostly of nitrogen, spiked with methane and other hydrocarbons, Titan's skies are thought to resemble those of a primordial Earth before life took hold.

Huygens, scientists say, could offer clues to how biology began on our own planet. But Titan's chemical makeup also created an orange smog so thick that it has stymied nearly all attempts to see what lies beneath.

Scientists expect that the data they collected yesterday will help resolve some long-standing debates about Titan, including whether frigid seas of methane or some other liquid hydrocarbon exist on its surface.

"Clearly there is liquid matter flowing on the surface," said planetary scientist Martin Tomasko of the University of Arizona, head of the probe's imaging team. The carved channeling in Huygens' photos, he says, "almost looks like a river delta."

Another photo of Huygens' landing site shows a flat landscape dotted with large boulders, which scientists said could be composed not of rock, but of frozen water.

"I think my biggest surprise about the images was they're not more exotic," says Kevin Grazier, a planetary scientist at NASA's Jet Propulsion Laboratory in California.

"If you handed someone this picture and said it was the American Southwest, I think people would believe it," he said.

In all, scientists expected the probe to capture 750 photos of its surroundings. Over the next several days they plan to add color to the initial black-and-white images and stitch together panoramas that provide sweeping views of the moon.

Getting to Titan was no easy feat. Huygens spent nearly seven years bolted to the back of NASA's Cassini spacecraft, which logged nearly two billion miles on its way to Saturn. The $3.3 billion mission will spend the next three years exploring the ringed planet and its 34 moons.

Cassini cut its 705-pound passenger loose on Christmas Eve, and Huygens spent three weeks free-falling toward Titan under the tug of the moon's gravity.

The first signs that Huygens had successfully entered the atmosphere came just before 5:30 a.m. Eastern yesterday, when the probe broadcast a carrier tone - similar to the dial tone on a telephone - that was picked up by a 110-meter radio telescope in Greenbank, W.Va., one of several around the world listening for the signal.

The tone indicated that the probe had shed its heat shield and deployed its main parachute.

"We heard the baby crying. The probe is alive," an ecstatic mission manager Jean-Pierre Lebreton told reporters.

As Huygens spiraled down to the moon's surface, its onboard instruments measured the temperature and composition of the atmosphere and nature of the moon's winds - measurements that were relayed to Cassini and stored on the mother ship's computers.

After landing on what appeared to be solid ground, the probe continued to transmit measurements from the surface - surprising scientists who had predicted that the probe's onboard batteries could give out within a half-hour of landing.

But radio telescopes continued to report picking up Huygens' signal more than five hours after its arrival - long after Cassini had passed out of range and left the probe behind.

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