Saturn's Moons as seen by Cassini

[mickw]

New images of Saturn's moon Dione were taken and released today.

The pockmarked moon is seen by NASA's Cassini spacecraft as a partial globe hanging in space, as well as in close-ups that reveal its many craters.

Dione is an icy ball. It has a radius of 348 miles (560 kilometers) and orbits Saturn every 2.73 days from 234,505 miles (377,400 kilometers) away.

More:   Dione

[mickw]

A NASA spacecraft has snapped some of the best-ever pictures of Saturn's moon Rhea, yielding clues about the satellite's recent tectonic rumblings.

NASA's Cassini probe captured the images — some of which shine bright in blue-and-green false color —on two recent flybys of Rhea, Saturn's second-largest moon. The photos show dramatic fractures cutting through craters on Rhea's surface, suggesting the satellite's interior churned and rumbled not too long ago, scientists said. [New Cassini photo of Rhea]

The pictures also reveal that Rhea bears a closer resemblance to another Saturn moon, Dione, than previously thought, researchers said.

"These recent, high-resolution Cassini images help us put Saturn's moon in the context of the moons' geological family tree," Cassini team member Paul Helfenstein of Cornell University said in a statement. "Since NASA's Voyager mission visited Saturn, scientists have thought of Rhea and Dione as close cousins, with some differences in size and density. The new images show us they're more like fraternal twins, where the resemblance is more than skin deep. This probably comes from their nearness to each other in orbit."

More   Rhea

[Whitters]

Is it Snowing Microbes on Enceladus?

In a series of tantalizingly close flybys to the moon, named "Enceladus," NASA's Cassini spacecraft has revealed watery jets erupting from what may be a vast underground sea. These jets, which spew through cracks in the moon's icy shell, could lead back to a habitable zone that is uniquely accessible in all the solar system.

"More than 90 jets of all sizes near Enceladus's south pole are spraying water vapor, icy particles, and organic compounds all over the place," says Carolyn Porco, an award-winning planetary scientist and leader of the Imaging Science team for NASA's Cassini spacecraft. "Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth's oceans."

Rich geysers aren't the only auspicious thing about Enceladus. Thermal measurements have revealed temperatures as high as -120 deg Fahrenheit (190 Kelvin) emanating from some of these fissures.

More: http://science.nasa.gov/science-news/science-at-nasa/2012/27mar_enceladus/

[Rick]

Cassini spacecraft finds sign of subsurface sea on Saturn's moon Enceladus

For years, the motto among astrobiologists — people who look for life in distant worlds, and try to understand what life is, exactly — has been "follow the water." You have to start the search somewhere, and scientists have started with liquid water because it's the essential agent for all biochemistry on Earth.

Now they've followed the water to a small, icy moon orbiting Saturn. Scientists reported Thursday that Enceladus, a shiny world about 300 miles in diameter, has a subsurface "regional sea" with a rocky bottom.

More on the Washington Post website

Also: http://www.nasa.gov/jpl/cassini/enceladus-pia18071/

[Rick]

Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon

Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon's underground sea all the way to its surface.

These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.

Over a period of almost seven years, Cassini's cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe" fractures and the geysers of tiny icy particles and water vapor first sighted there nearly 10 years ago. The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots. These relationships pointed the way to the geysers' origin.

More: http://www.jpl.nasa.gov/news/news.php?release=2014-246

[Rick]

Saturn's Moons: What a Difference a Decade Makes

Almost immediately after NASA's twin Voyager spacecraft made their brief visits to Saturn in the early 1980s, scientists were hungry for more. The Voyagers had offered them only a brief glimpse of a family of new worlds -- Saturn's icy moons -- and the researchers were eager to spend more time among those bodies.

The successor to the Voyagers at Saturn, NASA's Cassini spacecraft, has spent the past 10 years collecting images and other data as it has toured the Ringed Planet and its family of satellites. New color maps, produced from this trove of data, show that Cassini has essentially fulfilled one of its many mission objectives: producing global maps of Saturn's six major icy moons.

These are the large Saturnian moons, excluding haze-covered Titan, known before the start of the Space Age: Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus. Aside from a gap in the north polar region of Enceladus (to be filled in next year), and some areas of Iapetus, this objective is now more or less complete.

Go and take a look!

[Rick]

Saturn Moon's Activity Could Be 'Curtain Eruptions'

New research using data from NASA's Cassini mission suggests most of the eruptions from Saturn's moon Enceladus might be diffuse curtains rather than discrete jets. Many features that appear to be individual jets of material erupting along the length of prominent fractures in the moon's south polar region might be phantoms created by an optical illusion, according to the new study.

The research is being published on Thursday, May 7, in the journal Nature.

"We think most of the observed activity represents curtain eruptions from the 'tiger stripe' fractures, rather than intermittent geysers along them," said Joseph Spitale, lead author of the study and a participating scientist on the Cassini mission at the Planetary Science Institute in Tucson, Arizona. "Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets."

More: http://www.jpl.nasa.gov/news/news.php?feature=4575

[Carole]

They look like possible aurora.

Carole

[Rick]

Cassini Sends Back Views After Zooming Past Dione

The rugged landscape of Saturn's fracture-faced moon Dione is revealed in images sent back by NASA's Cassini spacecraft from its latest flyby. Cassini buzzed past Dione on June 16, coming within 321 miles (516 kilometers) of the moon's surface.

More: http://www.jpl.nasa.gov/news/news.php?feature=4630

[Rick]

Unusual Red Arcs Spotted on Icy Saturn Moon

ike graffiti sprayed by an unknown artist, unexplained arc-shaped, reddish streaks are visible on the surface of Saturn's icy moon Tethys in new, enhanced-color images from NASA's Cassini spacecraft.

The red arcs are narrow, curved lines on the moon's surface, and are among the most unusual color features on Saturn's moons to be revealed by Cassini's cameras.

Images taken using clear, green, infrared and ultraviolet spectral filters were combined to create the enhanced-color views, which highlight subtle color differences across the icy moon's surface at wavelengths not visible to human eyes.

More: http://www.jpl.nasa.gov/news/news.php?feature=4671

[Rick]

Cassini to Make Last Close Flyby of Saturn Moon Dione

NASA's Cassini spacecraft will zip past Saturn's moon Dione on Monday, Aug. 17 -- the final close flyby of this icy satellite during the spacecraft's long mission.

Cassini's closest approach, within 295 miles (474 kilometers) of Dione's surface, will occur at 11:33 a.m. PDT (2:33 p.m. EDT). Mission controllers expect fresh images to begin arriving on Earth within a couple of days following the encounter.

Cassini scientists have a bevy of investigations planned for Dione. Gravity-science data from the flyby will improve scientists' knowledge of the moon's internal structure and allow comparisons to Saturn's other moons. Cassini has performed this sort of gravity science investigation with only a handful of Saturn's 62 known moons.

More: http://www.jpl.nasa.gov/news/news.php?feature=4689

[Rick]

Cassini Finds Global Ocean in Saturn's Moon Enceladus

A global ocean lies beneath the icy crust of Saturn's geologically active moon Enceladus, according to new research using data from NASA's Cassini mission.

Researchers found the magnitude of the moon's very slight wobble, as it orbits Saturn, can only be accounted for if its outer ice shell is not frozen solid to its interior, meaning a global ocean must be present.

The finding implies the fine spray of water vapor, icy particles and simple organic molecules Cassini has observed coming from fractures near the moon's south pole is being fed by this vast liquid water reservoir. The research is presented in a paper published online this week in the journal Icarus.

Previous analysis of Cassini data suggested the presence of a lens-shaped body of water, or sea, underlying the moon's south polar region. However, gravity data collected during the spacecraft's several close passes over the south polar region lent support to the possibility the sea might be global. The new results -- derived using an independent line of evidence based on Cassini's images -- confirm this to be the case.

More: http://www.nasa.gov/press-release/cassini-finds-global-ocean-in-saturns-moon-enceladus

[Rick]

Closest Northern Views of Saturn's Moon Enceladus

NASA's Cassini spacecraft has begun returning its best-ever views of the northern extremes of Saturn's icy, ocean-bearing moon Enceladus. The spacecraft obtained the images during its Oct. 14 flyby, passing 1,142 miles (1,839 kilometers) above the moon's surface. Mission controllers say the spacecraft will continue transmitting images and other data from the encounter for the next several days.

Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. "The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters," said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. "These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well."

More: http://www.jpl.nasa.gov/news/news.php?feature=4738

[Rick]

Deepest-Ever Dive Through Enceladus Plume Completed

NASA's Cassini spacecraft successfully completed its close flyby of Saturn's moon Enceladus today, passing 30 miles (49 kilometers) above the moon's south polar region at approximately 8:22 a.m. PDT (11:22 a.m. EDT). Mission controllers established two-way communication with the spacecraft this afternoon and expect it to begin transmitting data from the encounter this evening. Images are anticipated in the next 24 to 48 hours.

Molre: http://www.jpl.nasa.gov/news/news.php?feature=4755

[Rick]

Saturn's Geyser Moon Shines in Close Flyby Views

NASA's Cassini spacecraft has begun transmitting its latest images of Saturn's icy, geologically active moon Enceladus, acquired during the dramatic Oct. 28 flyby in which the probe passed about 30 miles (49 kilometers) above the moon's south polar region. The spacecraft will continue transmitting its data from the encounter for the next several days.

"Cassini's stunning images are providing us a quick look at Enceladus from this ultra-close flyby, but some of the most exciting science is yet to come," said Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

More: http://www.jpl.nasa.gov/news/news.php?feature=4759