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Cassini 'CAT Scan' maps clumps in Saturn's rings, says UCF researcher, team
May 23, 2007Results may help explain origin of rings
Saturn's largest and most densely packed ring is composed of dense clumps of particles separated by nearly empty gaps, according to new findings from NASA's Cassini spacecraft.
These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists.
Previous interpretations assumed the ring particles were distributed uniformly and so scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.
"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida and a member of the Cassini ultraviolet imaging spectrograph team publishing its results in the journal Icarus this month.
Principal investigator Larry Esposito at the University of Colorado, Boulder is fascinated with the findings.
"The rings are different from the picture we had in our minds," Esposito said. "We originally thought we would see a uniform cloud of particles. Instead we find that the particles are clumped together with empty spaces in between. If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth. This is different from flying under a uniform cloud of particles."
The observations were made using the spectrograph aboard the Cassini spacecraft, which left earth in 1997 on a mission to collect detailed data about Saturn, its rings and moons. Cassini -- the largest interplanetary spacecraft launched from earth -- entered Saturn's orbit in July 2004, and scientists have been using sophisticated equipment on board to view and analyze images.
Boulder and UCF scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provides a measurement of the amount of ring material between the spacecraft and the star.
"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."
The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes." If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around Saturn counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they get to be about 30 to 50 meters (about 100 to 150 feet) across.
"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.
Colwell is a professor in UCF's growing program in planetary sciences. He joined the faculty because of the "opportunity to be involved in growing a new planetary sciences program."
University of Central Florida
Previous interpretations assumed the ring particles were distributed uniformly and so scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.
"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida and a member of the Cassini ultraviolet imaging spectrograph team publishing its results in the journal Icarus this month.
Principal investigator Larry Esposito at the University of Colorado, Boulder is fascinated with the findings.
"The rings are different from the picture we had in our minds," Esposito said. "We originally thought we would see a uniform cloud of particles. Instead we find that the particles are clumped together with empty spaces in between. If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth. This is different from flying under a uniform cloud of particles."
The observations were made using the spectrograph aboard the Cassini spacecraft, which left earth in 1997 on a mission to collect detailed data about Saturn, its rings and moons. Cassini -- the largest interplanetary spacecraft launched from earth -- entered Saturn's orbit in July 2004, and scientists have been using sophisticated equipment on board to view and analyze images.
Boulder and UCF scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provides a measurement of the amount of ring material between the spacecraft and the star.
"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."
The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes." If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around Saturn counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they get to be about 30 to 50 meters (about 100 to 150 feet) across.
"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.
Colwell is a professor in UCF's growing program in planetary sciences. He joined the faculty because of the "opportunity to be involved in growing a new planetary sciences program."
University of Central Florida
Cassini Current Events and Cassini News RSSESA spacecraft may help unravel cosmic mystery
When Europe's comet chaser Rosetta swings by Earth tomorrow for a critical gravity assist, tracking data will be collected to precisely measure the satellite's change in orbital energy. The results could help unravel a cosmic mystery that has stumped scientists for two decades.
A Long Night Falls Over Saturn's Rings
As Saturn's rings orbit the planet, a section is typically in the planet's shadow, experiencing a brief night lasting from 6 to 14 hours. However, once approximately every 15 years, night falls over the entire visible ring system for about four days.
Cassini Helps Redraw Shape of Solar System
In a paper published Oct. 15 in Science, researchers from the Johns Hopkins Applied Physics Laboratory (APL) present a new view of the region of the sun's influence, or heliosphere, and the forces that shape it. Images from one of the Magnetospheric Imaging Instrument's sensors, the Ion and Neutral Camera (MIMI/INCA), on NASA's Cassini spacecraft suggest that the heliosphere may not have the comet-like shape predicted by existing models.
NAE announces award winners John Casani and Sheila Widnall
During its 2009 annual meeting, the National Academy of Engineering (NAE) will present two awards for extraordinary impacts on the engineering profession.
CU-Boulder space scientists set for final spacecraft flyby of Mercury
NASA's MESSENGER spacecraft, which is toting an $8.7 million University of Colorado at Boulder instrument, will make its third and final flyby of Mercury on Sept. 29 -- a clever gravity-assist maneuver that will steer it into orbit around the rocky planet beginning in March 2011.
Deep Impact and Other Spacecraft Find Clear Evidence of Water on Moon
New data from the Deep Impact spacecraft and the Moon Mineralogy Mapper (M3), an instrument aboard India's recently ended Chandrayaan-1 spacecraft, provide, for the first time, clear evidence that water exists on the surface of the Moon.
Brown Scientists Announce Finding of Water on the Moon
Brown University scientists have made a major discovery: The moon has distinct signatures of water. The discovery came from a paper published in Science detailing findings from the Moon Mineralogy Mapper (M3), a NASA instrument aboard the Indian spacecraft Chandrayaan-1. Carle Pieters, professor of geological sciences at Brown, is the principal investigator of the M3 instrument and the lead author of the Science paper.
University of Hawai'i at Manoa team unravels the chemistry of Titan's hazy atmosphere
A team of University of Hawai'i at Mānoa researchers led by Ralf Kaiser, physical chemist at UH Mānoa, unraveled the chemical evolution of the orange-brownish colored atmosphere of Saturn's moon Titan, the only solar system body besides Venus and Earth with a solid surface and thick atmosphere.
Precise Radio-Telescope Measurements Advance Frontier Gravitational Physics
Scientists using a continent-wide array of radio telescopes have made an extremely precise measurement of the curvature of space caused by the Sun's gravity, and their technique promises a major contribution to a frontier area of basic physics.
Surface features on Titan form like Earth's, but with a frigid twist
"It is really surprising how closely Titan's surface resembles Earth's," says Rosaly Lopes, a planetary geologist at the Jet Propulsion Laboratory (JPL) in Pasadena, California, who is presenting the results on Friday, 7 August.
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Cassini at Saturn: Huygens Results (Springer Praxis Books / Space Exploration) by David M. Harland (Author) Cassini At Saturn – Huygens Results brings the story of the Cassini-Huygens mission and their joint exploration of the Saturnian system right up to date. Cassini entered orbit around Saturn June 2004 so this update includes 8 months of scientific data available for review, including the most spectacular images of Saturn, its rings and satellites ever obtained by a space mission. As the Cassini spacecraft approached its destination in spring 2004, the quality of the images already being returned by the spacecraft clearly demonstrated the spectacular nature of the close-range views that will be obtained. The book contains a 16-page colour section, comprising a carefully chosen selection of the most stunning images to be released during the spacecraft’s initial period of operation.... |
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Saturn: A New View by Laura Lovett (Author), Joan Horvath (Author), Jeff Cuzzi (Author), Kim Stanley Robinson (Foreword) After a journey of seven years and 2.2 billion miles, the spacecraft Cassini, with a probe named Huygens aboard, reached Saturn in July 2004, beginning a four-year tour to observe the remote planet, its rings, and its moons in depth. As a result of the spectacularly succesful Cassini-Huygens mission, photographs of astounding beauty have come streaming back to Earth, together with enough data to keep hundreds of scientists engrossed for decades. Reproduced here, in unprecedented detail and exquisite, high-quality format, are 150 of the best of those images, among them rings from the unlit side never visible from Earth and panoramas of the surface of Titan, Saturn’s largest moon. This breathtaking volume, including authoritative essays on the planetary system and the mission,... |
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Break a Leg Starring: Jennifer Beals, John Cassini, Molly Parker The nepotism that runs rife throughout the film world proves to be problematic for talented actor Max who can't seem to land a job. But Max has plenty of cunning and comes up with a devious plan to get ahead in the acting world giving a whole new meaning to the term BREAK A LEG.System Requirements:Running Time 97 Mins.Format: DVD MOVIE Genre: ACTION/ADVENTURE/THRILLERS Rating: NR UPC: 039414520569 Manufacturer No: MTI2056DVD |
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