Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Physical Chemistry

Everything's Organic on Titan

by Elizabeth K. Wilson
November 8, 2004 | A version of this story appeared in Volume 82, Issue 44

COMPLEXITY
[+]Enlarge
Credit: NASA PHOTO
This false-color infrared image shows the varying face of Titan, including a methane cloud at the South Pole. The inset shows the landing site of the Huygens probe, which will be deployed in late December and is currently aboard the Cassini spacecraft.
Credit: NASA PHOTO
This false-color infrared image shows the varying face of Titan, including a methane cloud at the South Pole. The inset shows the landing site of the Huygens probe, which will be deployed in late December and is currently aboard the Cassini spacecraft.

Peering through the thick atmospheric haze that surrounds Saturn's giant moon Titan, the Cassini spacecraft has uncovered a geological wonderland, suggesting a world of organic lakes, melted water and ammonia volcanoes, and sticky polymer surfaces.

During the craft's close-up flyby last week, numerous spectrometers, radar, and microwave instruments scanned a rectangle covering about 1% of Titan's surface. Early results from the instruments showed that organic molecules most likely blanket Titan's surface.

"The picture emerging is that Titan is really covered in organics," said Ralph Lorenz, a member of the Cassini mission radar imaging team at the University of Arizona, Tucson.

Titan's largely nitrogen atmosphere contains methane, which, when broken apart by sunlight, can recombine to form other molecules such as ethane, propane, and acetylene. These would fall to the surface as solids or liquids, "but how much is liquid or solid is still unclear. That's going to take a lot of work to tease out," said Jonathan I. Lunine, another Cassini team member at the University of Arizona.

Some of these surface deposits could be sticky or flaky. For example, frozen acetylene is a nondescript white material, but it readily polymerizes to form substances that could look metallic or black.

Images show bright rough areas that look similar to basaltic flows seen on Venus or Earth. But flows on Titan would not be caused by molten rock. Rather, upwellings would likely spring from melted water ice in its interior.

Fine bright features that stretch across dark areas may be cracks in a thin solid layer, like an eggshell. And mysterious streaks on the surface could be caused by wind.

"We now have strong evidence for active atmospheric processes--winds moving solids or liquids around," Lunine said.

A dark, cat-shaped area that may be a large lake has been dubbed "SiSi, the Halloween cat" (after the daughter of one of the team members), by Charles Elachi, director of the Jet Propulsion Laboratory, which manages the Cassini mission for NASA.

Advertisement

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.