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Burn ignition!
Mission control erupts in applause as communications from Cassini confirm the orbit insertion burn has begun. (60sec file)
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Burn completed
Signals from Cassini announce the conclusion of the Saturn orbit insertion burn, confirming the spacecraft has arrived at the ringed planet. (2min 15sec file)
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Post-arrival briefing
Mission officials hold a post-orbit insertion burn news conference at 1 a.m. EDT July 1 to discuss Cassini's successful arrival at Saturn. (25min 27sec file)
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Wednesday's status briefing
Cassini's health in the final hours before arrival at Saturn is presented in this status briefing from 12 p.m. EDT on June 30. (33min 09sec file)
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International cooperation
Officials from the U.S., European and Italian space agencies discuss the international cooperation in the Cassini mission and future exploration projects during this news conference from 2 p.m. EDT June 30. (19min 35sec file)
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'Ring-side' chat
This informal "ring-side chat" from 5 p.m. EDT June 30 discusses the Cassini mission to Saturn and the future of space exploration. (49min 20sec file)
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Cassini update
Mission managers and scientists provide an update on the Cassini mission and preview the spacecraft's arrival at Saturn during this news conference from June 29. (51min 58sec file)
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Phoebe science briefing
Scientists report scientific results from the Cassini spacecraft's close-up examination of Saturn's moon Phoebe. (31min 53sec file)
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Phoebe flyby preview
This animation shows Cassini during its encounter with the tiny moon Phoebe on the route to Saturn. (42sec file)
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Cassini preview
The Cassini spacecraft's arrival at Saturn is previewed in this detailed news conference from NASA Headquarters on June 3. (50min 01sec file)
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Saturn arrival explained
Cassini's make-or-break engine firing to enter orbit around Saturn is explained with graphics and animation. Expert narration is provided by Cassini program manager Robert Mitchell. (3min 33sec file)
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Cassini mission science
The scientific objectives of the Cassini mission to study the planet Saturn, its rings and moons are explained by Charles Elachi, director of the Jet Propulsion Laboratory. (4min 54sec file)
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Huygens mission science
After entering orbit around Saturn, the Cassini spacecraft will launch the European Huygens probe to make a parachute landing on the surface of the moon Titan. The scientific objectives of Huygens are explained by probe project manager Jean-Pierre Lebreton. (3min 14sec file)
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Cassini finds puzzles in Saturn's ring ingredients
NASA/JPL ANNOUNCEMENT
Posted: July 2, 2004

Just two days after the Cassini spacecraft entered Saturn orbit, preliminary science results are already beginning to show a complex and fascinating planetary system.

One early result intriguing scientists concerns Saturn's Cassini Division, the large gap between the A and B rings. While Saturn's rings are almost exclusively composed of water ice, new findings show the Cassini Division contains relatively more "dirt" than ice. Further, the particles between the rings seem remarkably similar to the dark material that scientists saw on Saturn's moon, Phoebe. These dark particles refuel the theory that the rings might be the remnants of a moon. The F ring was also found to contain more dirt.


Evidence from the visual and infrared mapping spectrometer on the Cassini spacecraft indicates that the grain sizes in Saturn's rings grade from smaller to larger, related to distance from Saturn. Those data (right) are shown next to a corresponding picture of the rings taken by Cassini's narrow angle camera. Saturn's rings are thought to be made up of boulder-size snowballs. By looking at the rings with the visual and infrared mapping spectrometer, the size of the ice crystals, or grains, on the surfaces of those boulders can be determined. Credit: NASA/JPL/University of Arizona
 
Another instrument on Cassini has detected large quantities of oxygen at the edge of the rings. Scientists are still trying to understand these results, but they think the oxygen may be left over from a collision that occurred as recently as January of this year.

"In just two days, our ideas about the rings have been expanded tremendously," said Dr. Linda Spilker, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., deputy project scientist for the Cassini-Huygens mission. "The Phoebe-like material is a big surprise. What puzzles us is that the A and B rings are so clean and the Cassini Division between them appears so dirty."

The visual and infrared mapping spectrometer onboard Cassini revealed the dirt mixed with the ice in the Cassini Division and in other small gaps in the rings, as well as in the F ring.

"The surprising fingerprint in the data is that the dirt appears similar to what we saw at Phoebe. In the next several months we will be looking for the origin of this material," said Dr. Roger Clark, of the U.S. Geological Survey, Denver, Colo., and a member of the Cassini science team.

Cassini's ultraviolet imaging instrument detected the sudden and surprising increase in the amount of atomic oxygen at the edge of the rings. The finding leads scientists to hypothesize that something may have collided with the main rings, producing the excess oxygen.

Dr. Donald Shemansky of the University of Southern California, Los Angeles, co-investigator for Cassini's ultraviolet imaging spectrograph instrument, said, "What is surprising is the evidence of a strong, sudden event during the observation period causing substantial variation in the oxygen distribution and abundance." Although atomic oxygen has not been previously observed, its presence is not a surprise because hydroxyl was discovered earlier from Hubble Space Telescope observations, and these chemicals are both products of water chemistry.

Cassini's examination of Saturn's atmosphere began while the spacecraft was still approaching the planet. Winds on Saturn near the equator decrease dramatically with altitude above the cloud tops. The winds fall off by as much 140 meters per second (approximately 300 miles per hour) over an altitude range of 300 kilometers (approximately 200 miles) in the upper stratosphere. This is the first time winds have been measured at altitudes so high in Saturn's atmosphere.

"We are finally defining the wind field in three dimensions, and it is very complex," said Dr. Michael Flasar of NASA Goddard Space Flight Center, Greenbelt, Md., principal investigator for Cassini's composite infrared spectrometer. "Temperature maps obtained now that Cassini is orbiting Saturn are expected to show more detail, helping us to unravel the riddles of Saturn's winds above the cloud tops."

Early Friday (Pacific Time), Cassini imaged Saturn's largest moon Titan, one of the prime targets for the mission. Titan is thought to harbor simple organic compounds that may be important in understanding the chemical building blocks that led to life on Earth. Although too cold to support life now, Titan serves as a frozen vault to see what early Earth might have been like. Scientists will receive the new data and images from Titan later Friday.

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. 

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Additional coverage for subscribers:
VIDEO: WATCH FRIDAY'S SCIENCE NEWS CONFERENCE QT

VIDEO: THURSDAY'S NEWS BRIEFING ON CASSINI'S FIRST PICTURES QT
VIDEO: RING PICTURES ARE PRESENTED WITH EXPERT NARRATION QT
VIDEO: CASSINI RE-DISCOVERS TINY MOONS ATLAS AND PAN QT
VIDEO: CASSINI BOOMING SOUNDS FROM BOW-SHOCK CROSSING QT

VIDEO: CASSINI BEGINS ENGINE FIRING TO ENTER ORBIT QT
VIDEO: BURN ENDS SUCCESSFULLY TO PUT CASSINI IN ORBIT QT
VIDEO: POST-ARRIVAL NEWS CONFERENCE QT

VIDEO: WEDNESDAY'S 12 P.M. EDT CASSINI STATUS BRIEFING QT
VIDEO: A LOOK AT INTERNATIONAL COOPERATION QT
VIDEO: 'RING-SIDE CHAT' ABOUT SPACE EXPLORATION QT
VIDEO: AN OVERVIEW OF CASSINI'S RADIO SCIENCE QT

VIDEO: TUESDAY'S CASSINI MISSION OVERVIEW BRIEFING QT
VIDEO: CASSINI'S ARRIVAL AT SATURN EXPLAINED QT
VIDEO: SCIENCE OBJECTIVES FOR CASSINI ORBITER QT
VIDEO: HUYGENS LANDER SCIENCE OBJECTIVES QT
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Mars rover collectible patch

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This commemorative patch celebrates NASA's Curiosity rover mission of the Mars Science Laboratory in search of clues whether the Red Planet was once hospitable to life.
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Columbia Report
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Mars Panorama

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Apollo 11 Mission Report
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Rocket DVD
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Columbia Report
A reproduction of the official accident investigation report into the loss of the space shuttle Columbia and its crew of seven.
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Mars Panorama

DISCOUNTED! This 360 degree image was taken by the Mars Pathfinder, which landed on the Red Planet in July 1997. The Sojourner Rover is visible in the image.
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Apollo 11 Mission Report
Apollo 11 - The NASA Mission Reports Vol. 3 is the first comprehensive study of man's first mission to another world is revealed in all of its startling complexity. Includes DVD!
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Rocket DVD
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Ares 1-X Patch
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Hubble Patch
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