Nov. 2, 2004 — The solar system's smoggiest orb appears to have landscapes both foreign and familiar, say geologists who are sorting through the first up-close peek at Saturn's planet-sized moon Titan.

What's familiar and Earth-like is Titan's apparent lack of impact craters and what look like volcanic flows. What's unearthly are the winds and rains that are probably at work wearing away craters, and what comes out of Titan's volcanoes, researchers said.

"This is definitely not a planet with an easy answer," said geologist Jonathan Lunine of the University of Arizona who is on the Cassini mission science team. "We didn't find a dead planet," he said, referring to the signs of active geology.

The lack of obvious impact craters means that like Earth — and unlike Mars, Mercury or Earth's moon — there is weather eroding the surface and erasing the craters on Titan.

That isn't necessarily a surprise, since Titan has a thick atmosphere with a pressure of more than one-and-a-half Earth atmospheres on the moon's surface. But with a top surface temperature of just -288 degrees Fahrenheit (-178 degrees Celsius), water can't be the weathering agent, said NASA headquarters' Cassini Program Scientist Denis Bogan.

"(Methane) could serve the role of water on Earth," Bogan said of Titan.

On the other hand, features that look like volcanic flows might be made of frozen water, said Lunine. The flows are likely the frozen outpourings of gigantic, low-lying slushy ice volcanoes, he said.

Of the three imaging systems on Cassini, the radar can best pierce Titan's orange hydrocarbon haze. The radar bounces radio waves off the moon's surface to create maps of different textures of ground.

In this first pass over Titan, the radar mapped a strip of the moon about two-thirds of a mile wide and 66 miles long, just one percent of Titan's surface. Although scientists are still cleaning the radar data of noise, they can already make out rough and smoother areas on the planet, though no great mountains or valleys have yet been detected, Bogan said.

Of that small portion of the surface, there is no sign yet of the highly radio-reflective flat surfaces detected by the Arecibo radio telescope a couple of years ago. At the time of the Arecibo experiment some researchers believed it was a sign that Titan had large lakes or oceans of liquid hydrocarbons.

"No one really knows what that means yet," said Lunine of how the Arecibo data stack up against Cassini observations.

Titan's surface should get a lot clearer, said Lunine, as Cassini makes additional close flybys and especially when the Huygens probe is dropped from Cassini for a quick journey through Titan's atmosphere in January.