[meteorite-list] Unusual Red Arcs Spotted on Icy Saturn Moon Tethys

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4671

Unusual Red Arcs Spotted on Icy Saturn Moon
Jet Propulsion Laboratory
July 29, 2015

[Image]
Unusual arc-shaped, reddish streaks cut across the surface of Saturn's 
ice-rich moon Tethys in this enhanced-color mosaic. The red streaks are 
narrow, curved lines on the moon's surface, only a few miles (or kilometers) 
wide but several hundred miles (or kilometers) long. 
Image Credit: NASA/JPL-Caltech/Space Science Institute 

Like graffiti sprayed by an unknown artist, unexplained arc-shaped, reddish 
streaks are visible on the surface of Saturn's icy moon Tethys in new, 
enhanced-color images from NASA's Cassini spacecraft.

The red arcs are narrow, curved lines on the moon's surface, and are among 
the most unusual color features on Saturn's moons to be revealed by Cassini's 
cameras.

Images taken using clear, green, infrared and ultraviolet spectral filters 
were combined to create the enhanced-color views, which highlight subtle 
color differences across the icy moon's surface at wavelengths not visible 
to human eyes.

A few of the red arcs can be seen faintly in observations made earlier 
in the Cassini mission, which has been in orbit at Saturn since 2004. 
But the color images for this observation, obtained in April 2015, are 
the first to show large northern areas of Tethys under the illumination 
and viewing conditions necessary to see the arcs clearly. As the Saturn 
system moved into its northern hemisphere summer over the past few years, 
northern latitudes have become increasingly well illuminated. As a result, 
the arcs have become clearly visible for the first time.

"The red arcs really popped out when we saw the new images," said Cassini 
participating scientist Paul Schenk of the Lunar and Planetary Institute 
in Houston. "It's surprising how extensive these features are."

The origin of the features and their reddish color is a mystery to Cassini 
scientists. Possibilities being studied include ideas that the reddish 
material is exposed ice with chemical impurities, or the result of outgassing 
from inside Tethys. They could also be associated with features like fractures 
that are below the resolution of the available images.

Except for a few small craters on Saturn's moon Dione, reddish-tinted 
features are rare on other moons of Saturn. Many reddish features do occur, 
however, on the geologically young surface of Jupiter's moon Europa.

"The red arcs must be geologically young because they cut across older 
features like impact craters, but we don't know their age in years." said 
Paul Helfenstein, a Cassini imaging scientist at Cornell University, Ithaca, 
New York, who helped plan the observations. "If the stain is only a thin, 
colored veneer on the icy soil, exposure to the space environment at Tethys' 
surface might erase them on relatively short time scales."

The Cassini team is currently planning follow-up observations of the features, 
at higher resolution, later this year.

"After 11 years in orbit, Cassini continues to make surprising discoveries," 
said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion 
Laboratory in Pasadena, California. "We are planning an even closer look 
at one of the Tethys red arcs in November to see if we can tease out the 
source and composition of these unusual markings."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European 
Space Agency) and the Italian Space Agency. JPL, a division of the California 
Institute of Technology in Pasadena, manages the mission for NASA's Science 
Mission Directorate in Washington. The Cassini imaging operations center 
is based at the Space Science Institute in Boulder, Colorado.

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov


Media Contact

Preston Dyches 
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches at jpl.nasa.gov 

2015-250