Pictures from Titan puzzle Saturn scientists

As the Cassini-Huygens spacecraft zooms away from Saturn on its first sweeping, orbital loop, it has left a wake of questions that has scientists buzzing about the craft’s first pass by the moon Titan.

Scientists expected to see oceans or lakes reflecting like mirrors from Titan’s surface. Instead, Cassini sent back murky pictures obscured by moon clouds.

“All of this is very mystifying,” Cassini’s imaging team leader, Carolyn Porco, said Monday. “We are trying to piece together a picture with really scant evidence.”

The ship snapped pictures and took instrument readings as it passed within 211,000 miles of Titan, about as close as Earth is to its own moon. The craft is soaring away from Saturn on the first orbit.

Titan is a focus of the $3.27 billion mission, which will spend at least four years exploring Saturn’s rings, moons, atmosphere and magnetic field. The multinational team of NASA, the European Space Agency and the Italian Space Agency launched the mission in 1997 with a focus on planet-like Titan because it is believed to be similar to primordial Earth.

Cassini will be back near Saturn in about 50 days, and in October, it will pass within 750 miles of Titan. Once in a tight orbit, Cassini’s regular passes within 600 miles will produce a steady stream of data.

Until then, scientists can only debate what they’ve seen so far.

The team wonders which of its assumptions were wrong. Are there no lakes or oceans, or is the haze in the atmosphere just much thicker than expected?

“It’s not obvious to us what we are seeing,” Porco says. “The paradigms we have are inadequate.”

Comparing Titan today to the Earth 4 billion years ago could be like opening a scientific time capsule, providing insight into the conditions in which life arose here.

Or it could raise new questions.

“It’s going to take all of the instruments and all of us working together to work out the story of Titan’s surface,” Porco says.

Though clouds obscured the view, they also provided scientists with clues. A methane cloud near Titan’s south pole is made of unusually large particles, suggesting something is brewing below.

And scientists were able to look for the first time at the surface, using an infrared mapping spectrometer that cut through the haze, to map minerals and chemicals.

“We have indeed seen Titan’s surface with unprecedented clarity,” said Dennis Matson, one of the project scientists. When the ship gets closer to Titan in coming months, the scientists will use radar to map the surface in greater detail. In January, a probe will descend to the surface.

Friday’s distant flyby, primarily a braking and navigational move, gave Cassini a good view of how Titan interacts with huge Saturn.

Cassini showed a vast swarm of hydrogen molecules surrounding Titan, which is one of 31 known moons circling the planet.