Oct. 27, 2004 —Humanity's first look at the largest piece of unexplored real estate in the solar system raised more questions than answers among scientists on the Cassini Saturn project.

The spacecraft on Tuesday made its first close approach of the moon Titan, the only planetary satellite in the solar system that sports its own thick atmosphere.

"Last night, the solar system became a smaller place," said Carolyn Porco, the Cassini imaging science team leader with the Space Science Institute in Boulder, Colo.

During Tuesday's flyby, Cassini used its science instruments to peer for the first time at surface features of Titan, although researchers have no idea what they are.

"It seems to be young surface, with no craters and no shadows," Porco said. "We can't say for sure at this point whether there are liquid seas on Titan."

Scientists have theorized that oceans of liquid methane and ethane could exist on the moon's surface, although they doubt the organic stew contains life forms, as the temperatures on Titan are believed to be about minus 290 degrees Fahrenheit.

From Cassini's close encounter, however, the team has learned that Titan is a "super-rotator," like Venus, with an atmosphere that spins faster than the solid body beneath it.

The wind speeds, roughly similar to what is experienced on Earth, may be the source of some or all of the surface features on Titan, which appear as light and dark shapes. Oddly, initial results show the composition of the features to be the same.

"If there is a pattern there is something going on," Porco said. "It could be geophysical or some surface- atmospheric interaction. We're still mystified. We're not sure what we're looking at."

Cassini flew by Titan as it entered Saturn's orbit in July to begin a four-year study. The data and images during the flyby Tuesday, however, are 10 times better resolution, Porco added.

"You always find something new when you have better resolution, " she said. "It's just that we can't figure out what that something is."

Cassini passed within about 745 miles, or 1,200 kilometers, from the surface of Titan, which is as close as the science team dared without having better information about the moon's atmosphere. On future passes, Cassini is expected to dip as close as 590 miles, or 950 kilometers.

"Essentially we just dipped our toes into the lowest altitude we knew was safe," said Earl Maize, deputy manager of the Cassini program at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The information will help the science team not only assess how much closer Cassini can safely fly for future passes, but also refine the flight path for a probe that is to be cast away from the mothership on Dec. 24 for a parachute descent through Titan's atmosphere.

"Cassini may finally show us if what we thought of this moon is true, and whether the Huygens probe touchdown will be a splash," said Jean-Pierre Lebreton, Huygens project manager.

Added Porco, "There's a lot of work left to do. Our exploration of Titan is really just beginning."