Titan: The New World

<B>Scott Pelley</B> Reports On The NASA Mission To Earth's Closest Relative

This past weekend, one of the most dramatic space missions ever gave us the first peek at the most mysterious world in our solar system.

It's a body with an atmosphere, weather and much the same chemistry that gave rise to life here on Earth. Scientists believe it may be Earth's closest relative in the known universe.

The new world is Titan, the largest moon in orbit around Saturn.

This weekend, a flying saucer – no kidding - pierced the clouds and sent back images of what appear to be hills, rivers, ice and a sea on a world that is fearsomely dark and cold.

But Titan's surface was essentially unknown until the pictures came back to Earth. Correspondent Scott Pelley reports.

Scientists believe that the landscape of Titan - nearly a billion miles from Earth - may resemble, in deep freeze, what Earth was like before life took hold.

"This is one of the greatest achievements in the history of space exploration," says Claudio Sollazzo, manager of the Huygens space probe that landed on Titan over the weekend.

He was among the first to be shocked by a 360-degree panoramic of Titan's real estate, because there seemed to be prime shoreline at the bottom.

"Oh my God, this is incredible. This is like, it looks like my hometown," says Sollazzo. "There is a huge beach. There is a dark sea and there are things that look like hills on the back."

Well, it doesn't exactly look like Naples. And the sea isn't water. It may be liquid natural gas, ethane or methane -- same idea as the fuel in a gas grill. It's a liquid at Titan's temperature of 290 degrees below zero.

Some of these images look like inkblots until you see what the scientists can see. We are told that the ground of Titan appears to be spongy, somewhat like wet clay. And in one high altitude image that was taken looking straight down, scientists believe that they can see channels of flowing liquid running perhaps downhill to an area that appears to be a beach and then dark sea beyond.

These are among the first early theories. An image of Titan in color appears overcast by an orange smog sky with what appears to be ice balls on the surface. They're only a few inches across. Man has never landed a spacecraft on a world so far away. And these images are just one of the discoveries in a $3-billion mission to explore the Saturn system.

The mission called Cassini left this world back in 1997. It was a project of NASA's Jet Propulsion Laboratory and the European Space Agency. This nuclear powered robot, as big as a bus, is in orbit around Saturn, studying how planets and possibly life developed in the solar system. Cassini is named after the 17th century astronomer who discovered a gap in Saturn's rings. It's fitting because to reach its orbit, Cassini had to cannonball right through the rings.

"If you hit something the size of a rock, mission over," says Pelley.

"That's correct," says Jerry Jones, the chief navigator of the mission. "We're going so fast relative to the rings, it would just, you know, go right through the spacecraft, break it up. We'd never hear from it again."

But they did hear from Cassini – and you can hear the actual sound of space dust hitting the antenna as the ship passed through the rings. When Jones got the first signal back from Cassini, after it had gone through the rings, he said it was "deep breath time."

How does he explain his job? "I'm really a bus driver," says Jones. "In fact, when you think of Cassini, it really is the size of a bus. And so we like to think of our scientists with all of their instruments as the kids in the back of the bus."

And you can think of Carolyn Porco as the kid with the camera. She's the imaging team chief, and now, she's shooting some of the best close-ups ever.

"What motivates me are, you know, the just wonderful feelings of excitement we get at looking at something that's alien. You know, it just has to be part of our nature that we always want to know what's around the next corner," says Porco. "And then, when we finally see something that has never been seen before, and you know, this is the first time in human history that this has ever been done. It is a rush. It's that fix we're all looking for."

What's the history of the rings of Saturn?

"The rings are no older than about a few hundred million years. They're young. They are basically geologically young," says Porco. "It means that rings, Saturn's rings, were not in there in the early days when dinosaurs roamed the Earth."

What are they made of?

"Billions and billions of particles. Countless numbers of particles. Varying ice particles. Varying size from the sizes of houses, large houses or small apartment buildings, down to the sizes of stones and pebbles," says Porco. "And although they're screaming around Saturn at speeds of 40,000 miles an hour, they are very gently jostling each other."

They are the delicate wreckage of a moon, or maybe a comet that was ripped apart and captured by Saturn's gravity. Being in charge gives her the privilege of naming the pictures. "Ringworld Waiting" was taken more than 17 million miles away. "Side Swiping Saturn" is a view of the seemingly paper-thin ring level view. And "Nature's Canvas" captures Saturn's tiny moon, Mimas.

Cassini has discovered three new moons. Now Saturn has 34. But Titan, with its active weather, stands apart from just about everything else in the solar system.

There aren't too many people who can say they've been to Saturn twice. But Torrence Johnson was part of the team that shot the Voyager spacecraft past Saturn two decades ago.

It was a brief encounter. Now, he's back to study what Titan has in common with Earth.

"Titan's the only moon in the solar system with what you call a major atmosphere," says Johnson. "It's got an atmosphere made out of mostly nitrogen with several percent methane added to it."

"And being mostly nitrogen, it's very much like Earth," says Pelley.

"We think that a lot of the things that are going on in Titan now are very similar to what happened four-and-a-half billion years ago in the Earth's atmosphere before life arose," says Johnson. "And that's one of the allures of this place, for because it's kind of like a cosmic time machine. … What we may learn is something about our own origins, basically."

The trouble is, Titan's atmosphere is so thick that no one had ever seen the surface clearly -- making it the solar system's largest unexplored world. In October, Cassini flew by Titan, trying to peer at the ground.

In the radar room, world-renowned experts in geology, radar and Saturn were stumped. Ever wonder what all those genius kids in your science classes are doing with their lives?

"We knew we'd be surprised, and we were right," says one geologist, laughing.

The flyby pictures were tantalizing and tormenting. But they wouldn't make their breakthrough discovery until a few days ago.

On Christmas Eve, Cassini launched the Huygens probe, which looks a lot like a 1950s Hollywood flying saucer. It's named for the astronomer who discovered Titan. Huygens hit Titan's atmosphere like a bullet.

Huygens could have plunged into a methane sea, but it parachuted to a soft, 12-miles-an-hour landing on a solid surface. It transmitted about 350 pictures over several hours before it signed off forever when its batteries went dead.

"She was left in a savage, cold, harsh environment," says Sollazzo. "But she was strong enough to arrive there, to land and to survive for so long. I think she'll be happy there."

Jonathan Lunine has been looking at Titan since he was a graduate student 24 years ago. He says studying this alien world may help us find an answer to the biggest question in the cosmos.

"Titan is a place where the raw materials for life are present, and chemistry is still acting on these materials," says Lunine. "And if we find that these raw materials have made it at the surface a certain distance towards the origin of life itself, the building blocks of life have been created from these raw materials, then it tells us that doing those first steps is relatively easy."

"Not a one time accident. But maybe common," says Pelley.

"Not a one-time accident that requires such a special set of conditions that we can't expect it somewhere else," says Lunine.

Cassini has become the farthest outpost man has ever established. For the next four years, it will continue to explore Saturn and its constellation of moons.

"I think the exploration of the solar system is the greatest of human endeavors," says Porco. "It's the signature enterprise of our time. It's what our culture, in the late 20th century, early 21 century, will be remembered for."