|Volume: 03, Issue: 08||04/20/2005|
Cassini Zooms In on TitanThe Cassini spacecraft closed in on Saturnís largest moon, Titan, more than once in the past few weeks. Cassini has now performed six flybys of Titan, but much of the moon remains for the spacecraft to explore.
The latest flyby of the smoggy moon was April 16. Cassini came within 637 miles of the moon's surface, and scientists hope the low altitude of this flyby may provide important clues about the magnetosphere around Titan.
Cassini also successfully flew by Titan at a distance of 1,493 miles on March 31. Titan's haze was the focus of ultraviolet observations during this brush with the moon. By mapping its haze, scientists hope to learn more about particle size and properties. Titan's transient clouds were also studied during the flyby.
Titan's northern hemisphere was previously imaged with Cassini's radar instrument in October 2004 and February 2005. This time, Cassini's optical cameras got their best view of the same area, as did the visual and infrared mapping spectrometer.
Titan is a prime target of the Cassini-Huygens mission because it is the only moon in our solar system with a thick, smoggy atmosphere. The observations of both the Cassini spacecraft and Huygens probe have demonstrated that the large moon shares some of the same qualities as the young Earth.
Cassini was launched more than seven years ago and has traveled 3.55 billion kilometers (2.2 billion miles). All 12 of Cassini's instruments have been returning data. Recently, scientists noticed episodic interferences on the composite infrared spectrometer that were traced back to the time of orbit insertion. A mirror on the spectrometer is showing some signs of jitter. The movement may be associated with the use of the spacecraft reaction wheels, used for spacecraft pointing control. A motor on one of three sensors on the magnetospheric imaging instrument and another motor on the plasma spectrometer are also not working properly. All three instruments continue to function, however, with some reduced level of science data collection.
"We are working to understand why the instruments are not performing properly, but it is likely to be a few weeks before we have definitive answers," said Robert T. Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory. "When running a mission for this long, you expect to have a few glitches. Cassini has been working remarkably well considering the duration and complexity of the mission."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Science Mission Directorate.
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