Titan's Enigmatic Infrared-Bright Spot Is Surface Make-Up

October 6, 2005
ombined VIMS and ISS images of Titan's mysterious bright red spot gives researchers more information about the feature than eith

A 300-mile-wide patch that outshines everything else on Titan at long infrared wavelengths appears not to be a mountain, a cloud or a geologically active hot spot, University of Arizona scientists and Cassini team members say.

Image: Combined VIMS and ISS images of Titan's mysterious bright red spot gives researchers more information about the feature than either single view. (Credit: NASA/JPL/University of Arizona/Space Science Institute)

"We must be looking at a difference in surface composition," said Jason W. Barnes, a postdoctoral researcher at UA's Lunar and Planetary Lab. "That's exciting because this is the first evidence that says not all of the bright areas on Titan are the same. Now we have to figure out what those differences are, what might have caused them."

When NASA's Cassini spacecraft flew by Titan on March 31 and again on April 16, its visual and infrared mapping spectrometer saw a feature that was spectacularly bright at 5-micron wavelengths just southeast of the continent-sized region called Xanadu.

The bright spot occurs where Cassini's visible-wavelength imaging cameras photographed a bright arc-shaped feature approximately the same size in December 2004 and February 2005.

Cassini's radar instrument, operating in the "passive" mode that is sensitive to microwaves emitted from a planetary surface, saw no temperature difference between the bright spot and surrounding region. That rules out the possibility that the 5-micron bright spot is a hot spot, such as a geologically active ice volcano, Barnes said.

Cassini microwave radiometry also failed to detect a temperature drop that would show up if some two-mile high mountain rose from Titan's surface, he said.

And if the 5-micron bright spot is a cloud, it's a cloud that hasn't moved or changed shape for three years, according to ground-based observations made at the Keck Telescope and with Cassini's visual and infrared mapping spectrometer during five different flybys. "If this is a cloud," Barnes said, "it would have to be a persistent ground fog, like San Francisco on steroids, always foggy, all the time."

"The bright spot must be a patch of surface with a composition different from anything we've seen yet. Titan's surface is primarily composed of ice. It could be that something is contaminating the ice here, but what this might be is not clear," Barnes said.

"There's a lot left to explore about Titan. It's a very complex, exciting place. It's not obvious how it works. It's going to be a lot of fun over the next couple of years figuring out how Titan works," he said.

Barnes and 34 other scientists report the research in the Oct. 7 issue of Science. Authors include UA Lunar and Planetary Laboratory scientists and Cassini team members Robert H. Brown, head of Cassini's visual and infrared mapping spectrometer team; Elizabeth P. Turtle and Alfred S. McEwen of the Cassini imaging team; Ralph D. Lorenz of the Cassini radar team; Caitlin Griffith of the Cassini visual and infrared mapping team; and Jason Perry and Stephanie Fussner, who work with McEwen and Turtle on Cassini imaging.

Source: University of Arizona

Explore further: Our living planet shapes the search for life beyond Earth

Related Stories

The cosmic water trail uncovered by Herschel

September 19, 2017

During almost four years of observing the cosmos, the Herschel Space Observatory traced out the presence of water. With its unprecedented sensitivity and spectral resolution at key wavelengths, Herschel revealed this crucial ...

Odd spot on Titan baffles scientists

May 25, 2005

Saturn's moon Titan shows an unusual bright spot that has scientists mystified. The spot, approximately the size and shape of West Virginia, is just southeast of the bright region called Xanadu and is visible to multiple ...

Cassini Reveals Earth-like Land on Titan

July 20, 2006

New radar images from NASA's Cassini spacecraft revealed geological features similar to Earth on Xanadu, an Australia-sized, bright region on Saturn's moon Titan.

Recommended for you

World's smallest tape recorder is built from microbes

November 23, 2017

Through a few clever molecular hacks, researchers at Columbia University Medical Center have converted a natural bacterial immune system into a microscopic data recorder, laying the groundwork for a new class of technologies ...

The world needs to rethink the value of water

November 23, 2017

Research led by Oxford University highlights the accelerating pressure on measuring, monitoring and managing water locally and globally. A new four-part framework is proposed to value water for sustainable development to ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.