[meteorite-list] Cassini Provides New Views of Titan, Saturn's Largest Moon

[Ron Baalke]

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.naas.gov

Carolina Martinez (818) 354-5011 						
Jet Propulsion Laboratory, Pasadena, Calif.		

Donald Savage (202) 358-1727
NASA Headquarters, Washington

NEWS RELEASE: 2004-171		July 3, 2004

CASSINI PROVIDES NEW VIEWS OF TITAN, SATURN'S LARGEST MOON

The Cassini spacecraft has revealed surface details of 
Saturn's moon Titan and imaged a huge cloud of gas 
surrounding the planet-sized moon.  

Cassini gathered data before and during a distant flyby of
 the orange moon yesterday. Titan's dense atmosphere is 
opaque at most wavelengths, but the spacecraft captured 
some surface details, including a possible crater, through 
wavelengths in which the atmosphere is clear.

"Although the initial images appear bland and hard to 
interpret, we're happy to report that, with a combination 
of instruments, we have indeed seen Titan's surface with 
unprecedented clarity. We also look forward to future, much 
closer flybys and use of radar for much greater levels of 
surface detail," said Dr. Dennis Matson of NASA's Jet 
Propulsion Laboratory, Pasadena, Calif., project scientist 
for the international Cassini-Huygens mission. 

Cassini's visible and infrared mapping spectrometer pierced 
the smog that enshrouds Titan. This instrument, capable of 
mapping mineral and chemical features of the moon, reveals 
an exotic surface bearing a variety of materials in the 
south and a circular feature that may be a crater in the 
north.  Near-infrared colors, some three times redder than 
the human eye can see, reveal the surface with unusual clarity.

"At some wavelengths, we see dark regions of relatively pure 
water ice and brighter regions with a much higher amount of 
non-ice materials, such as simple hydrocarbons. This is 
different from what we expected. It's preliminary, but it may 
change the way we interpret light and dark areas on Titan," 
said JPL's Dr. Kevin Baines, Cassini science-team member. "A 
methane cloud is visible near the south pole. It's made of 
unusually large particles compared to the typical haze 
particles surrounding the moon, suggesting a dynamically 
active atmosphere there."

This is the first time scientists are able to map the 
mineralogy of Titan. Using hundreds of wavelengths, many of 
which have never been used in Titan imaging before, they are 
creating a global map showing distributions of 
hydrocarbon-rich regions and areas of icy material. 

Cassini's camera also sees through the haze in some 
wavelengths. "We're seeing a totally alien surface," said Dr. 
Elizabeth Turtle of the University of Arizona, Tucson. "There 
are linear features, circular features, curvilinear features. 
These suggest geologic activity on Titan, but we really don't 
know how to interpret them yet. We've got some exciting work cut 
out for us."

Since entering orbit, Cassini has also provided the first view 
of a vast swarm of hydrogen molecules surrounding Titan well 
beyond the top of Titan's atmosphere. Cassini's magnetospheric 
imaging instrument, first of its kind on any interplanetary 
mission, provided images of the huge cloud sweeping along with 
Titan in orbit around Saturn. The cloud is so big that Saturn 
and its rings would fit within it. "The top of Titan's 
atmosphere is being bombarded by highly energetic particles in 
Saturn's radiation belts, and that is knocking away this 
neutral gas," said Dr. Stamatios Krimigis of Johns Hopkins 
Applied Physics Laboratory, Laurel, Md., principal investigator 
for the magnetospheric imager. "In effect, Titan is gradually 
losing material from the top of its atmosphere, and that 
material is being dragged around Saturn."

The study of Titan, Saturn's largest moon, is one of the major 
goals of the Cassini-Huygens mission. Titan may preserve in 
deep-freeze many chemical compounds that preceded life on Earth. 
Friday's flyby at a closest distance of 339,000 kilometers 
(210,600 miles) provided Cassini's best look at Titan so far, 
but over the next four years, the orbiter will execute 45 Titan 
flybys as close as approximately 950 kilometers (590 miles). 
This will permit high-resolution mapping of the moon's surface 
with an imaging radar instrument, which can see through the 
opaque haze of Titan's upper atmosphere. In January 2005, the 
Huygens probe that is now attached to Cassini will descend 
through Titan's atmosphere to the surface.

During the ring plane crossing, the radio and plasma wave 
science instrument on Cassini measured little puffs of plasma 
produced by dust impacts. While crossing the plane of Saturn's 
rings, the instrument detected up to 680 dust hits per second. 
"The particles are comparable in size to particles in cigarette 
smoke," said Dr. Don Gurnett of the University of Iowa, Iowa City, 
principal investigator for the instrument. "When we crossed the 
ring plane, we had roughly 100,000 total dust hits to the 
spacecraft in less than five minutes. We converted these into 
audible sounds that resemble hail hitting a tin roof." 

The spacecraft reported no unusual activity due to the hits and 
performed flawlessly, successfully going into orbit around 
Saturn on June 30. The engine burn for entering orbit went so 
well that mission managers have decided to forgo an 
orbital-adjustment maneuver scheduled for today.

The Cassini-Huygens mission is a cooperative project of NASA, 
the European Space Agency and the Italian Space Agency. The Jet 
Propulsion Laboratory, a division of the California Institute of 
Technology in Pasadena, manages the Cassini-Huygens mission for 
NASA's Office of Space Science, Washington, D.C.  JPL designed, 
developed and assembled the Cassini orbiter.  

For the latest images and more information about the 
Cassini-Huygens mission, visit 

http://saturn.jpl.nasa.gov and 

http://www.nasa.gov/cassini .

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