NASA's Cassini spacecraft successfully photographed one of the most mysterious objects in our solar system on Tuesday in a flyby that brought it within 745 miles of Saturn's hazy moon Titan.
However, scientists analyzing the photographs back on Earth say they are baffled by what they see.
The images, downloaded from the spacecraft by the Jet Propulsion Laboratory on Tuesday night, are the most detailed ever taken of Titan and can reveal objects as small as 200 meters wide on the moon's surface. But so far, the only things mission investigators are seeing are more of the same light and dark patches that they saw in earlier photographs. And what exactly causes those patches is still anybody's guess.
"We are not quite sure what we're looking at," said Cassini imaging team leader Carolyn Porco during a press conference on Wednesday. "From what we can tell right now, it could all be flat. We could be seeing light material and dark material all at the same level, (but) we don't know."
Additional images taken by Cassini's Visual and Infrared Mapping Spectrometer, or VIMS, revealed that the light and dark regions reflect sunlight at the same wavelength -- a sign that they are possibly composed of the same material.
Another option is that the regions are made of different substances but coated in the same sort of translucent material, said Robert Brown, VIMS team leader at the University of Arizona, where the instrument was created. "It's certainly not what we expected."
The one thing the scientists are certain about is the existence of clouds at Titan's southern pole. Tuesday's images clearly show bright clouds forming and changing shapes near the pole. Porco said the movement of these clouds, as captured in successive images, is a good indicator that Titan is a "super rotator." This means that, like Venus, Titan's atmosphere rotates much faster than its surface.
In another observation, the scientists noted that the sunlight reflecting off a thin band of the moon's surface during the photo session didn't cause anything to sparkle. Without this sparkle, they can't be sure of the existence of lakes or oceans of toxic ethane or methane on the planet.
Still, the Cassini team remains confident that it will solve the mystery of what lies on Titan's surface sometime within the next four years. That's how long the Cassini spacecraft will continue to explore the Saturnian system, which includes the planet, its rings and its moons.
Mission planners have singled out Titan in particular for extended exploration because it is the only moon in our solar system known to have an atmosphere. It is also the second-largest moon, after Jupiter's Ganymede.
One of the team's best chances for making discoveries will come in late December and early January, when Cassini returns to Titan and releases the European Space Agency's Huygens probe into the moon's atmosphere. Huygens will then orbit Titan until Jan. 14, when it will deploy a parachute and drift down to Titan's surface, all the while sending data back to the Cassini orbiter.
The probe will crash into the moon or splash into one of its ethane or methane oceans -- if any exist -- after approximately 2.5 hours. If it's not damaged at that point, the probe could continue sending data to Cassini for an additional 30 minutes before its batteries run out.
