Saturn-bound Cassini probe sees its destination
Posted: November 1, 2002

Credit: NASA/JPL/Southwest Research Institute
Saturn appears serene and majestic in the first color composite made of images taken by NASA's Cassini spacecraft on its approach to the ringed planet, with arrival still 20 months away.

The planet was 285 million kilometers (177 million miles) away from the spacecraft, nearly twice the distance between the Sun and Earth, when Cassini took images of it in various filters as an engineering test on Oct. 21, 2002.

It is summer in Saturn's southern hemisphere. The Sun is a lofty 27 degrees below the equator and casts a semi-circular shadow of the planet on the rings. The shadow extends partway across the rings, leaving the outer A ring in sunlight. The last Saturn-bound spacecraft, Voyager 2, arrived in early northern spring. Many features seen in Voyager images -- spoke-like markings on the rings, clouds and eddies in the hazy atmosphere, ring-shepherding moons -- are not yet visible to Cassini.

Titan, Saturn's largest moon, appears in the upper left. It is the only moon resolved from this distance. This composite uses a threefold enhancement in the brightness of Titan relative to the brightness of Saturn. Titan is a major attraction for scientists of the Cassini-Huygens mission. They will study its haze-enshrouded atmosphere and peer down, with special instrumentation, to its surface to look for evidence of organic processes similar to those that might have occurred on the early Earth, prior to the emergence of life.

"Cassini has sighted the ringed planet looking distant, mysterious and serene," said Dr. Carolyn Porco, a planetary scentist at Southwest Research Institute in Boulder, Colo., and leader of the science team using the Cassini camera. "Our anticipation has been building for years, so it's good to know our destination is in view."

Dr. Dennis Matson, Cassini project scientist at JPL in Pasadena, Calif., said, "This is an emotional event for the mission. We now have Saturn in our sights."

Cassini camera-team member Dr. Alfred McEwen at the University of Arizona, Tucson, added, "Seeing the picture makes our science-planning work suddenly seem more real. Now we can see Saturn and we'll watch it get bigger as a visual cue that we're approaching fast. It's good to see the camera is working well."

Fourteen camera-team scientists selected by NASA will use the camera to investigate many features of Saturn, its moons and its rings. Cassini will begin a four-year prime mission in orbit around Saturn when it arrives on July 1, 2004. It will release a piggybacked probe, Huygens, to descend through the thick atmosphere of Titan on Jan. 14, 2005.

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 mission for NASA's Office of Space Science, Washington, D.C.

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