*EPF306 10/27/2004
Cassini Completes First High-Resolution Reconnaissance of Titan
(Scientists need time to interpret data and images from Saturn's moon) (700)

By Cheryl Pellerin
Washington File Staff Writer

Washington -- The first high-resolution reconnaissance of Saturn's largest moon, Titan, shows dark and light features and possible striations on the surface, but scientists at an October 27 NASA press briefing are "not quite sure" yet what the images mean.

Calling Titan the "solar system's last great mystery, Cassini-Huygens mission imaging team leader Carolyn Porco, said "We can confidently say that there are linear trends, perhaps linear features on the surface, but we're not exactly sure what they're telling us."

The Cassini spacecraft beamed back information and pictures October 26 after skimming the hazy atmosphere of Saturn's moon Titan, long hidden behind a thick veil of haze.

NASA's Deep Space Network tracking station in Madrid, Spain, acquired a signal at about 6:25 p.m. Pacific Daylight Time. The spacecraft came within 1,200 kilometers of Titan's surface, the closest any spacecraft has ever come to that moon.

Although it will be days, perhaps weeks, before researchers can begin to interpret the Cassini data, team member Hunter Waite, team leader of the Ion and Neutral Mass Spectrometer and a professor in the University of Michigan Department of Atmospheric, Oceanic and Space Sciences, said Titan offered two initial surprises.

Cassini made solid measurements of nitrogen and methane, Waite said, but "we were surprised to see complex carbon species [carbon-containing molecules]" 1,200 kilometers above the moon's surface. "This may have been suggested theoretically," he said, "but we were surprised that we could see them at such a high altitude."

Studying carbon chemistry on Titan could help scientists apply that knowledge to carbon and its functions on Earth.

The second surprise involved Titan's atmospheric evolution; Waite said up to three-quarters of the moon's atmosphere might have been lost over geologic time. More data will be needed to confirm this finding, he said.

Titan is a prime target of the Cassini-Huygens mission because it is the only moon in the solar system with an atmosphere. It is a cosmic time capsule that offers a look back in time to see what Earth might have been like before the appearance of life.

An important goal of the flyby is to confirm scientists' model of Titan's atmosphere to prepare for the Huygens probe descent. The probe, built and managed by the European Space Agency, will be released from its mother ship Cassini on December 24 and will coast through the atmosphere of Titan.

On the way down, the probe will sample Titan's opaque atmosphere with a sophisticated set of scientific instruments. On January 14, 2005, it will touch down on the surface to collect data.

This first in-place sampling of Titan's atmosphere will help scientists understand the atmosphere's density and composition, which will help them manage the Huygens probe. This flyby marked the first time Cassini's imaging radar was used to observe Titan, and is expected to provide topographical maps and show whether there is a liquid or solid surface.

"Titan has been lying still, waiting. Cassini may finally show us if what we thought of this moon is true, and whether the Huygens probe touchdown will be a splash," said Dr. Jean-Pierre Lebreton, Huygens project manager and project scientist for the European Space Research and Technology Center, Noordwijk, Netherlands.

So far, team leader Porco said, there is no evidence of liquid on Titan's surface.

Of Cassini's 12 instruments, 11 were aimed at Titan during the encounter. Scientists hope to learn more about Titan's interior structure, surface, atmosphere and interaction with Saturn's magnetosphere.

Titan is larger than Mercury or Pluto and is the second largest moon in the solar system, after Jupiter's moon, Ganymede. Titan is a cold place thought to be inhospitable to life at 95 degrees Kelvin (minus 289 degrees Fahrenheit).

Cassini has performed flawlessly since entering orbit around Saturn on June 30.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

Information and images from Cassini are available at http://www.nasa.gov/cassini

Mission information and raw images are available at http://saturn.jpl.nasa.gov

(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)

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