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Deep Impact arrives
NASA's Deep Impact comet spacecraft arrives at the Astrotech Space Operations Facility near Kennedy Space Center to begin final launch preparations for blastoff December 30 aboard a Boeing Delta 2 rocket. (2min 53sec file)
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Swift preview
Mission scientists preview NASA's Swift gamma-ray burst detection satellite being readied for launch into Earth orbit. (39min 49sec file)
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Cassini science update
Radar imagery of Saturn's moon Titan and other new data from the Cassini spacecraft is presented during this JPL news conference on Thursday. (54min 48sec file)
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Post-flyby briefing
Scientists and mission officials discuss the initial pictures and data obtained during Cassini's flyby of Titan during this JPL news conference on Wednesday. (55min 18sec file)
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First pictures
The first pictures taken by Cassini during this close encounter with Titan are received at the Jet Propulsion Laboratory to the delight of the mission's imaging leader. (2min 21sec file)
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Images flood in
A Cassini mission scientist provides analysis as the raw images taken of Titan's surface flood into the Jet Propulsion Laboratory. (29min 29sec file)
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Flyby explained
Detailed animation illustrates Cassini's flyby of Titan and how the probe's instruments will study this moon of Saturn. Expert narration is provided by a project official. (3min 09sec file)
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Cassini captures Saturn moon red-handed
CASSINI PHOTO RELEASE
Posted: December 4, 2004

Stealing is a crime on Earth, but at Saturn, apparently it is routine. The Cassini spacecraft has witnessed Saturn's moon Prometheus snatching particles from one of Saturn's rings.


Credit: NASA/JPL/Space Science Institute
Download larger image version here

 
This potato-shaped moon is also believed to be responsible for kinks within Saturn's thin F ring, a contorted, narrow ring flanked by two small moons, Prometheus and Pandora. The thievery and the detailed behavior of kinks were observed for the first time ever in images taken by the Cassini spacecraft.

In an image taken on Oct. 29, Prometheus is seen stealing particles from the F ring while connected to the ringlets by a faint streak of material. A movie sequence of the ring, taken on Oct. 28, captures in freeze-frame motion the zigzagging kinks and knots, some of which are almost certainly caused by Prometheus.

The kinks look like "hiccups" traveling around the ring. Consisting of 44 frames taken three minutes apart, the sequence represents almost two hours, or about one-eighth of the orbital period of F ring particles around the planet.

Cassini was on a flight path that took the spacecraft away from the planet and farther south, so that the rings appear to tilt upward. The top portion of the F ring is closer to the spacecraft, while the bottom portion is farther away and curves around the far side of Saturn.

Scientists are not sure exactly how Prometheus is interacting with the F ring here, but they have speculated that the moon might be gravitationally pulling material away from the ring. Scientists speculate that the ring particles may end up in a slightly different orbit from the one they were in prior to getting a 'kick' from the moon. These kicks occur at specific locations in the rings and can actually cause large waves or knots to form. In the still image, gaps in the diffuse inner strands are seen. All these features appear to be due to the influence of Prometheus in ways that are not fully understood.

Saturn's moon Prometheus is following in the footsteps of the legendary Titan for which it is named. In Greek mythology, Prometheus stole fire from the gods and gave it to the mortals.

Scientists will use what they learn about Prometheus' interaction with the F ring to understand the gravitational exchanges between moons and rings, which give rise to so much of the structure that is observed in Saturn's rings.

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 Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

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