Titan Images Reveal Dynamic Surface and an Apparent Lake

The first radar images of Saturn’s smoggy moon Titan show what appears to be a large lake, rolling ridges and lava-like flows of ice or ammonia, researchers at Pasadena’s Jet Propulsion Laboratory said Thursday.

The images from the Cassini spacecraft provide the best evidence yet that lakes, or even seas, exist on Titan’s surface, team members said.

The potential lake was christened “Si-Si the Halloween Cat” in honor of a scientist’s daughter, who first noted the feline resemblance. It appeared as a blackened-out area about the size of Lake Tahoe on the radar image.

The Cassini team urged caution in interpreting the findings, because the black-and-white radar image covered only 1% of the moon’s surface, roughly a swath of land 75 miles wide and 1,250 miles long. Over the next four years, Cassini is scheduled to make 44 more close passes of Titan, providing what scientists said should be a much clearer picture of the solar system’s second-largest moon.

Some space scientists say the frozen moon could turn out to be the strangest place in the solar system. Not only is it likely to possess methane lakes and water ice, but the surface appears to be heavily carpeted in organic material, such as ethane, propane and acetylene. Those compounds had already been observed high in the moon’s atmosphere.

Researchers speculate the surface might possess the consistency of powder, flakes or even sticky, plastic-like substances.

“Titan is an extremely dynamic and active place,” said Jonathan Lunine, a Cassini scientist from the University of Arizona. Though too cold for life at minus 290 degrees Fahrenheit, Titan appears to be a massive organic chemistry laboratory, in which carbon-based substances could be endlessly combining and recombining into a wide variety of molecules.

“Titan is really covered in organics,” said Ralph Lorenz, a member of the radar imaging team.

Cassini’s radar also produced streaky images that scientists said could be ice ridges. Other images resembled lava-like flows. They couldn’t be from an erupting volcano, however, because Titan’s interior isn’t hot enough to melt rock.

Though its atmosphere is much denser than Earth’s, the moon is much less massive, being composed of equal proportions of water ice and rock. The flows on Titan are likely melted water and possibly ammonia, Lunine said.

Lunine speculated that the ridges were the result of the very thin surface cracking open under pressure like an eggshell.

Scientists hope to learn more when Cassini sends its Huygens probe to the surface in January. If it survives the landing, Huygens is designed to measure the atmosphere, as well as the surface, possibly answering questions as to whether Titan has a gloppy, sticky, powdery or rocky surface -- or all of the above.

The $3.2-billion mission is a collaboration between NASA, the European Space Agency and the Italian Space Agency.