News about Saturn's Rings as seen from Cassini

[Rick]

The spyware/adblocker discussion triggered by some of the stuff space.com serves up has gone over to the PC chatter section...

[Rick]

Bright Clumps in Saturn Ring Now Mysteriously Scarce

Compared to the age of the solar system -- about four-and-a-half billion years -- a couple of decades are next to nothing. Some planetary locales change little over many millions of years, so for scientists who study the planets, any object that evolves on such a short interval makes for a tempting target for study. And so it is with the ever-changing rings of Saturn.

Case in point: Saturn's narrow, chaotic and clumpy F ring. A recent NASA-funded study compared the F ring's appearance in six years of observations by the Cassini mission to its appearance during the Saturn flybys of NASA's Voyager mission, 30 years earlier. The study team found that, while the overall number of clumps in the F ring remained the same, the number of exceptionally bright clumps of material plummeted during that time. While the Voyagers saw two or three bright clumps in any given observation, Cassini spied only two of the features during a six-year period. What physical processes, they wondered, could cause only the brightest of these features to decline sharply?

More: http://www.jpl.nasa.gov/news/news.php?release=2014-302

[Rick]

At Saturn, One of These Rings is not like the Others

When the sun set on Saturn's rings in August 2009, scientists on NASA's Cassini mission were watching closely. It was the equinox -- one of two times in the Saturnian year when the sun illuminates the planet's enormous ring system edge-on. The event provided an extraordinary opportunity for the orbiting Cassini spacecraft to observe short-lived changes in the rings that reveal details about their nature.

Like Earth, Saturn is tilted on its axis. Over the course of its 29-year-long orbit, the sun's rays move from north to south over the planet and its rings, and back again. The changing sunlight causes the temperature of the rings -- which are made of trillions of icy particles -- to vary from season to season. During equinox, which lasted only a few days, unusual shadows and wavy structures appeared and, as they sat in twilight for this brief period, the rings began to cool.

In a recent study published in the journal Icarus, a team of Cassini scientists reported that one section of the rings appears to have been running a slight fever during equinox. The higher-than-expected temperature provided a unique window into the interior structure of ring particles not usually available to scientists.

More: http://www.jpl.nasa.gov/news/news.php?feature=4709

[Rick]

Saturn's Rings: Less than Meets the Eye?

It seems intuitive that an opaque material should contain more stuff than a more translucent substance. For example, muddier water has more suspended particles of dirt in it than clearer water. Likewise, you might think that, in the rings of Saturn, more opaque areas contain a greater concentration of material than places where the rings seem more transparent.

But this intuition does not always apply, according to a recent study of the rings using data from NASA's Cassini mission. In their analysis, scientists found surprisingly little correlation between how dense a ring might appear to be -- in terms of its opacity and reflectiveness -- and the amount of material it contains.

More: http://www.jpl.nasa.gov/news/news.php?feature=4886

[Rick]

Cassini Makes First Ring-Grazing Plunge

NASA's Saturn-orbiting Cassini spacecraft has made its first close dive past the outer edges of Saturn's rings since beginning its penultimate mission phase on Nov. 30.

Cassini crossed through the plane of Saturn's rings on Dec. 4 at 5:09 a.m. PST (8:09 a.m. EST) at a distance of approximately 57,000 miles (91,000 kilometers) above Saturn's cloud tops. This is the approximate location of a faint, dusty ring produced by the planet's small moons Janus and Epimetheus, and just 6,800 miles (11,000 kilometers) from the center of Saturn's F ring.

About an hour prior to the ring-plane crossing, the spacecraft performed a short burn of its main engine that lasted about six seconds. About 30 minutes later, as it approached the ring plane, Cassini closed its canopy-like engine cover as a protective measure.

More: http://www.jpl.nasa.gov/news/news.php?feature=6690

[Rick]

Close Views Show Saturn's Rings in Unprecedented Detail

Newly released images showcase the incredible closeness with which NASA's Cassini spacecraft, now in its "Ring-Grazing" orbits phase, is observing Saturn's dazzling rings of icy debris.

The views are some of the closest-ever images of the outer parts of the main rings, giving scientists an eagerly awaited opportunity to observe features with names like "straw" and "propellers." Although Cassini saw these features earlier in the mission, the spacecraft's current, special orbits are now providing opportunities to see them in greater detail. The new images resolve details as small as 0.3 miles (550 meters), which is on the scale of Earth's tallest buildings.

More: http://www.jpl.nasa.gov/news/news.php?feature=6729

[Rick]

Cassini Mission Prepares for 'Grand Finale' at Saturn

NASA's Cassini spacecraft, in orbit around Saturn since 2004, is about to begin the final chapter of its remarkable story. On Wednesday, April 26, the spacecraft will make the first in a series of dives through the 1,500-mile-wide (2,400-kilometer) gap between Saturn and its rings as part of the mission's grand finale.

"No spacecraft has ever gone through the unique region that we'll attempt to boldly cross 22 times," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "What we learn from Cassini's daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve. This is truly discovery in action to the very end."

More: https://www.jpl.nasa.gov/news/news.php?feature=6803