Image 1 - Cassini Eyes Blazing Trails In Saturn’s F-ring
April 25, 2012

Cassini Eyes Blazing Trails In Saturn’s F-ring

Brett Smith for

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Scientists studying images from NASA´s Cassini spacecraft have found evidence of massive snowballs dragging glittering trails from one of Saturn´s rings.

Saturn´s F ring has often been thought to be the most affected of the giant plant´s rings, often changing its look over the course of hours. The orbiting debris field measures a few hundred miles wide and is shepherded around the planet by two moons, Prometheus and Pandora.

At first, the Cassini imaging team was primarily interested in studying the effect that Prometheus has on the F ring. For years, scientists have known that the 92-mile-long icy moon manipulates the ring in a number of ways. Discovery of these debris trails occurred serendipitously when the Cassini team was scanning images of Prometheus.

“We have a new analysis of images obtained by Cassini that show the F Ring is actually even more dynamic than we thought,” said Carl Murray, a Cassini imaging team member based at Queen Mary University of London, England.

“For the first time, we can see some of the havoc wreaked by objects about a kilometer in diameter.”

In 2005, scientists found that gravitational forces around Prometheus periodically cause disturbances in the F ring, such as creating channels and ripples. The disturbances have also been found to create giant kilometer-wide snowballs.

The fate of these giant snowballs was mostly unknown until scientists discovered what they are calling “mini-jets” streaking from the F ring. These jets are the result of the snowballs colliding with ring debris at around 5 mph and punching material out of the ring to form trails that can have a single or multiple prongs.

In researching these mini-jets, scientists studied about 20,000 images generated by Cassini. They located around 500 pictures of these snowballs in action.

This discovery will help scientists to further understand how planetary bodies interact with other objects in space, including large debris fields.

"Beyond just showing us the strange beauty of the F ring, Cassini's studies of this ring help us understand the activity that occurs when solar systems evolve out of dusty disks that are similar to, but obviously much grander than, the disk we see around Saturn," Cassini project scientist Linda Spilker said. "We can't wait to see what else Cassini will show us in Saturn's rings."

The Cassini spacecraft, named after the Italian Renaissance astronomer Giovanni Domenico Cassini, was launched in 1997 after almost two decades of development. Its mission is to study Saturn and its satellites, which it began doing after entering into orbit in 2004. A few months after entering into orbit, Cassini launched the Huygens probe. The probe would eventually land on Saturn´s Titan moon. It was the first landing to occur outside our solar system´s first four planets.

In 2008, the ground based operations for NASA´s Cassini program were funded for an additional two years, at which point the program was dubbed, the Cassini Equinox Mission. In 2010, the program, renamed Cassini Solstice Mission, was extended into 2017. Cassini is the fourth craft of its kind to visit Saturn.


Image 1: Cassini mosaic of Saturn's rings on August 12, 2009, a day after equinox. With the rings pointed at the Sun, illumination is from light reflected off Saturn, except on thicker or out-of-plane sections, like the F Ring. Credit: NASA/JPL/Space Science Institute

Image 2: The constant change in Saturn's wavy, wiggly F ring is on display in this set of images obtained by NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI/QMUL