Saturn's Moon Enceladus & Its Geysers

[Waspie_Dwarf]

Saturn's Moon Enceladus & Its Geysers

This thread deals with Cassini's exploration of Enceladus. Discoveries about Saturn's moon Titan, can be found here: Exploration of Titan - Saturn's Largest Moon. Many of the images made using that spacecraft's optical camera's can be found in the Cassini - Images of Saturn & Its Moons thread. Infrared discoveries can be found in the Cassini - Infrared Images thread. Other major announcements and discoveries may be found in separate threads.

--------------------------------------------------------------------------------------------

NASA-funded Study Says Saturn's Moon Enceladus Rolled Over

May 31, 2006
(Source: Jet Propulsion Laboratory / University of Santa Cruz, Calif. / University of Colorado, Boulder)

Saturn's moon Enceladus -- an active, icy world with an unusually warm south pole -- may have performed an unusual trick for a planetary body. New research shows Enceladus rolled over, literally, explaining why the moon's hottest spot is at the south pole.

Enceladus recently grabbed scientists' attention when the Cassini spacecraft observed icy jets and plumes indicating active geysers spewing from the tiny moon's south polar region.

"The mystery we set out to explain was how the hot spot could end up at the pole if it didn't start there," said Francis Nimmo, assistant professor of Earth sciences, University of California, Santa Cruz.

The researchers propose the reorientation of the moon was driven by warm, low-density material rising to the surface from within Enceladus. A similar process may have happened on Uranus' moon Miranda, they said. Their findings are in this week's journal Nature.

"It's astounding that Cassini found a region of current geological activity on an icy moon that we would expect to be frigidly cold, especially down at this moon's equivalent of Antarctica," said Robert Pappalardo, co-author and planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We think the moon rolled over to put a deeply seated warm, active area there." Pappalardo worked on the study while at the University of Colorado.

Rotating bodies, including planets and moons, are stable if more of their mass is close to the equator. "Any redistribution of mass within the object can cause instability with respect to the axis of rotation. A reorientation will tend to position excess mass at the equator and areas of low density at the poles," Nimmo said. This is precisely what happened to Enceladus.

Nimmo and Pappalardo calculated the effects of a low-density blob beneath the surface of Enceladus and showed it could cause the moon to roll over by up to 30-degrees and put the blob at the pole.

Pappalardo used an analogy to explain the Enceladus rollover. "A spinning bowling ball will tend to roll over to put its holes -- the axis with the least mass -- vertically along the spin axis. Similarly, Enceladus apparently rolled over to place the portion of the moon with the least mass along its vertical spin axis," he said.

The rising blob (called a "diapir") may be within either the icy shell or the underlying rocky core of Enceladus. In either case, as the material heats up it expands and becomes less dense, then rises toward the surface. This rising of warm, low-density material could also help explain the high heat and striking surface features, including the geysers and "tiger-stripe" region suggesting fault lines caused by tectonic stress.

Internal heating of Enceladus probably results from its eccentric orbit around Saturn. "Enceladus gets squeezed and stretched by tidal forces as it orbits Saturn, and that mechanical energy is transformed into heat energy in the moon's interior," added Nimmo.

Future Cassini observations of Enceladus may support this model. Meanwhile, scientists await the next Enceladus flyby in 2008 for more clues.

This research was supported by grants from NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of Caltech, manages the mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL.

For images and information about the Cassini mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

NEWS RELEASE: 2006-080

Source: NASA/JPL - Cassini - Press Release Edited May 22, 2007 by Waspie_Dwarf

[Waspie_Dwarf]

Enceladus roll

May 31, 2006

This graphic illustrates the interior of Saturn's moon Enceladus. It shows warm, low-density material rising to the surface from within, in its icy shell (yellow) and/or its rocky core (red). A NASA-funded study says Enceladus might have rolled or rotated itself to place this area of low density at the south pole. This finding is in the June 1, 2006, issue of the journal Nature.

This graphic uses parts of visible-light images taken by the Cassini spacecraft camera that have been modified for the purpose of showing the interior structure. Cassini's cameras captured a giant plume blasting icy particles into space.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Abecrombie]

great topic to post waspie,... i know isnt that whole idea of a moon rotating upward and over a frillen trip or what.

i read of this night before last on a nother nasa link i beileved it was called near earth objects newsline. spacenews update or something a ma gig ? anyway im so glad you posted it because it blew me away.

thanks for the great picture too

Abecrombie

[Waspie_Dwarf]

great topic to post waspie.

thanks for the great picture too

Abecrombie

Thanks Abecrombie, but really it's NASA you should thank. I just do the re-posting.

[Waspie_Dwarf]

A Moon's Telltale Tail

June 12, 2006

The plumes of Enceladus continue to gush icy particles into Saturn orbit, making this little moon one of a select group of geologically active bodies in the solar system.

Enceladus (505 kilometers, or 314 miles across) is seen here against the night side of Saturn. The extended exposure time used to image the plumes also makes the southern hemisphere, illuminated by ring-shine, appear bright.

The image was acquired in visible light with the Cassini spacecraft narrow-angle camera on May 4, 2006 at a distance of approximately 2.1 million kilometers (1.3 million miles) from Enceladus and 2.3 million kilometers (1.5 million miles) from Saturn. The image was taken at a Sun-Enceladus-spacecraft, or phase, angle of 159 degrees. Image scale is 13 kilometers (8 miles) per pixel on Enceladus.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Master Sage]

A Moon's Telltale Tail

June 12, 2006

The plumes of Enceladus continue to gush icy particles into Saturn orbit, making this little moon one of a select group of geologically active bodies in the solar system.

Enceladus (505 kilometers, or 314 miles across) is seen here against the night side of Saturn. The extended exposure time used to image the plumes also makes the southern hemisphere, illuminated by ring-shine, appear bright.

The image was acquired in visible light with the Cassini spacecraft narrow-angle camera on May 4, 2006 at a distance of approximately 2.1 million kilometers (1.3 million miles) from Enceladus and 2.3 million kilometers (1.5 million miles) from Saturn. The image was taken at a Sun-Enceladus-spacecraft, or phase, angle of 159 degrees. Image scale is 13 kilometers (8 miles) per pixel on Enceladus.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

We keep finding new ice everywhere. H2O seems to be perhapd the most common compound in the universe.

[Waspie_Dwarf]

Scattered Ice, Scattered Light

June 14, 2006

An enhanced close-up view shows at least two distinct jets spraying a mist of fine particles from the south polar region of Enceladus. The particles in the plume scatter sunlight most effectively at high Sun-Enceladus-spacecraft angles, or phase angles, making the plumes appear bright.

This image shows the night side of Saturn and the active moon against dark sky. Enceladus is 505 kilometers (314 miles) across.

Some artifacts due to image compression and cosmic rays striking the camera's detector remain as noise in the image.

The image was acquired in polarized green light with the Cassini spacecraft narrow-angle camera on May 4, 2006 at a distance of approximately 2.1 million kilometers (1.3 million miles) from Enceladus and 2.3 million kilometers (1.4 million miles) from Saturn. The image was taken at a Sun-Enceladus-spacecraft, or phase, angle of 159 degrees. Image scale is 13 kilometers (8 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Enceladus Exudes an Air of Mystery

June 29, 2006
(Source: Jet Propulsion Laboratory)

Atomic oxygen could never be confused with expensive perfume. But just as a fragrance lingering in the air of an empty room offers hints about a previous occupant, the cloud of oxygen the Cassini spacecraft encountered as it first approached Saturn turned out to be a calling card from another celestial presence, the tiny moon Enceladus.


Cassini's ultraviolet imaging spectrograph
observed the star Gamma Orionis as
Enceladus crossed in front of the star. The
light of the star dimmed as it was obscured
by the atmosphere before being blocked
entirely by Enceladus itself.

--------------------------------------------------------------------------------

The oxygen was the first clue that much more is going on beneath Enceladus' icy surface than it first appeared. It took a while for scientists to get the message. Tracking down the oxygen's source led them to a most unusual spot in the solar system, a place that may possess one of the rarest and most sought-after substances in the universe - liquid water.

Now You See It, Now You Don't

Cassini's ultraviolet imaging spectrograph made its initial survey of Saturn's atmosphere late in December 2003 as the spacecraft neared the end of its seven-year voyage to the ringed planet. Along with the expected hydrogen, long known to be the gas giant's major component, the spectrograph detected the presence of oxygen. "We were the first to discover the oxygen in the Saturn system," says Dr. Larry Esposito of the University of Colorado, principal investigator for the instrument. Since Saturn's rings are made mostly of water ice, it wasn't surprising to find one ingredient of water, oxygen, in Saturn's atmosphere, he explains. The oxygen they observed was in the form of single oxygen atoms, called atomic oxygen, like that in water, H2O.

In January 2004, when it looked again at Saturn's atmosphere, it found a massive bubble of oxygen near Saturn's outermost ring, the E ring. Then just a few months later, much of the oxygen was gone. "What was surprising was the amount of oxygen we saw and how it changed," says Esposito. "This was the first sign that something unusual was going on."


A view of Enceladus showing largely the
southern hemisphere and the south polar
terrain at the bottom of the image.

--------------------------------------------------------------------------------


"Our first idea was that the collisions between small moons in the rings would release small puffs of ice and that ice would be broken down into its atoms, one of which would be atomic oxygen," Esposito explains. "We put out this hypothesis, but the idea didn't seem to be working out."

What did work out were a host of observations in spring 2005 showing that something very odd was taking place on Enceladus, which just happens to orbit within the E ring, where the mysterious cloud of oxygen was first discovered. Cassini's magnetometer showed that the moon had an atmosphere. Too small to have enough gravity to hold on to an atmosphere for very long, Enceladus had to have a steady source of gas, such as geysers, to keep an atmosphere going. The cosmic dust analyzer detected a stream of particles around Enceladus. The scientists wondered whether these particles could be coming from the moon or from the E ring and if, perhaps, the moon itself might be the source of ice particles for the E ring.

The Cassini science teams were eager to get a closer look. Mission navigators re-designed the spacecraft's trajectory to bring it closer to Enceladus than had been previously planned. "This is a big advantage of a mission like Cassini," according to Esposito. "You don't just fly by once, you can follow-up when something seems promising."

Ready for a Close-Up


The E ring, a ring feature now known to be
created by Enceladus.

--------------------------------------------------------------------------------


In July 2005, Cassini cruised only 175 kilometers (109 miles) from Enceladus. The spacecraft's instruments revealed that the large dark cracks, dubbed "tiger stripes," on the moon's south pole were warm and spewing out water vapor and ice particles.

The flyby occurred just when a star was moving behind the moon's southern pole. "As we watched the moon extinguish the light from the star, the spectrometer identified oxygen," says Esposito. "The starlight showed water molecules between us -- the spacecraft -- and the star. It showed a localized cloud of water near Enceladus."

"We were able to measure the shape of the cloud, estimate the amount of water it contained and the rate it would be destroyed and produce oxygen," says Esposito. The amount of water they saw, about a million tons, was exactly that needed to provide a cloud of oxygen like the one they had first observed near the E ring more than a year earlier. "This was a most pleasing result," says Esposito. "We measured two new distinct phenomena and found that they fit together."

The mystery of the atomic oxygen was solved. At the same time, its source, the diminutive Enceladus revealed itself to be completely different than the cold, dead icy moon it should have been. Small as it is, it has an internal heat source and is geologically active. Its geysers throw out enough water vapor and ice to maintain the moon's atmosphere, feed the vast E ring, and decompose into clouds of oxygen like the one first spotted by Cassini on its way to Saturn.

Not far beneath the moon's snowy white surface, scientists say, may be large pools of liquid water, warmed by the same heat source that powers its geysers. Its potential for water puts Enceladus into an elite group of places where life could exist. The Cassini spacecraft will swing back in 2008 for another look.

To learn more about Enceladus, visit http://saturn.jpl.nasa.gov/science/moons/moonDetails.cfm?pageID=83


Source: NASA/JPL - Cassini - News Feature Edited June 30, 2006 by Waspie_Dwarf

[Waspie_Dwarf]

Boosting the Signal

July 21, 2006

The ice jets of Enceladus send particles streaming into space hundreds of kilometers above the south pole of this spectacularly active moon. Some of the particles escape to form the diffuse E ring around Saturn.

This color-coded image was processed to enhance faint signals, making the contours and extent of the fainter, larger-scale component of the plume easier to see.

The bright strip behind and above Enceladus (505 kilometers, 314 miles across) is the E ring, in which this intriguing body resides. The small round object at far left is a background star.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 24, 2006 at a distance of approximately 1.9 million kilometers (1.2 million miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 162 degrees. Image scale is 11 kilometers (7 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Moon With a Warm Heart

August 22, 2006

Few large craters are to be found in the wrinkled terrain of Enceladus, where the surface has been reworked by geologic processes presumably resulting from the moon's inner warmth.

Cassini spied the bright crescent of Enceladus (505 kilometers, or 314 miles across) on July 23, 2006 at a distance of approximately 628,000 kilometers (391,000 miles). The image was taken in visible light with the Cassini spacecraft narrow-angle camera at a Sun-Enceladus-spacecraft, or phase, angle of 103 degrees. Image scale is 4 kilometers (2 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Living Moon

September 4, 2006

Enceladus continues to exhale water ice into Saturn orbit, keeping the E ring topped off with tiny particles.

Enceladus (505 kilometers, or 314 miles across) is a source of much interest for planetary scientists, being nearly seven times smaller than Earth's own moon, yet having active geology that appears to involve near-surface liquid water.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Aug. 11, 2006 at a distance of approximately 2.2 million kilometers (1.3 million miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 164 degrees. Image scale is 13 kilometers (8 miles) per pixel

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Enigma in Ice

September 28, 2006

Cassini spies the wrinkled, fractured and remarkably crater-poor terrain of Enceladus. Scientists are working to understand what causes the moon's surprising geologic activity (see Fountains of Enceladus).

North on Enceladus (505 kilometers, 314 miles across) is up and rotated 20 degrees to the left.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 8, 2006 at a distance of approximately 560,000 kilometers (348,000 miles) from Enceladus and at a Sun- Enceladus-spacecraft, or phase, angle of 103 degrees. Image scale is 3 kilometers (2 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

A Folded Surface

October 4, 2006

The wrinkled border of Enceladus' south polar region snakes across this view, separating fresher, younger terrain from more ancient, cratered provinces.

This is the region of Enceladus (505 kilometers, or 314 miles across) that is known to be presently geologically active. At right are clearly visible ridges and troughs thought to be caused by compressional stresses across the icy surface.

The image was taken in polarized green light with the Cassini spacecraft narrow-angle camera on Sept. 9, 2006 at a distance of approximately 66,000 kilometers (41,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 104 degrees. Image scale is 396 meters (1,300 feet) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Half-lit Enceladus

October 12, 2006

A world whose mysteries are just coming to light, Enceladus has enchanted scientists and non-scientists alike. With its potential for near-surface liquid water, the icy moon may be the latest addition to the list of possible abodes for life.

The view was acquired about two-and-a-half hours after A Folded Surface, during an encounter with Enceladus (505 kilometers, or 314 miles across).

The image was taken using a combination of spectral filters sensitive to wavelengths of polarized ultraviolet light. The Cassini spacecraft narrow-angle camera acquired the view on Sept. 9, 2006 at a distance of approximately 141,000 kilometers (877,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 96 degrees. Image scale is 850 meters (0.5 mile) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Bella-Angelique]

That is an interesting cross pattern. I wonder what they think caused that?

[Waspie_Dwarf]

Relaxing on Enceladus

November 17, 2006

Looking down onto the northern hemisphere of geologically complex Enceladus, the Cassini spacecraft spies softened, or "relaxed," craters and east-west trending fractures and faults.

The anti-Saturn hemisphere of Enceladus (505 kilometers, or 314 miles across) is lit here.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 12, 2006 at a distance of approximately 521,000 kilometers (324,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 101 degrees. Image scale is 3 kilometers (2 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Out of the Noise

December 5, 2006

A ghostly view of Enceladus reveals the specter of the moon's icy plume of fine particles. Scientists continue to monitor the plume, where mission planning allows, using the Cassini spacecraft's imaging cameras.

This view looks toward northern latitudes on the trailing hemisphere of Enceladus (505 kilometers, or 314 miles across). North is up.

The image was taken with the Cassini spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers on Oct. 31, 2006. Cassini was then at a distance of approximately 1.4 million kilometers (900,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 148 degrees. Image scale is 8 kilometers (5 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Arabian Sulci

December 13, 2006

Enceladus shows off its tortured south polar terrain, which is crosscut by the roughly parallel furrows and ridges called sulci, or informally, "tiger stripes."

Several features on Enceladus were recently given names by the International Astronomical Union in accord with the naming convention for the icy moon, which draws from characters and places from The Arabian Nights. The four most prominent sulci are named Alexandria, Cairo, Baghdad and Damascus.

Lit terrain in this view is on the anti-Saturn side of Enceladus (505 kilometers, or 314 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 8, 2006 at a distance of approximately 399,000 kilometers (248,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 75 degrees. Image scale is 2 kilometers (1 mile) per pixel.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Ice Fountains

December 29, 2006

Multiple jets of icy particles are blasted into space by the active venting on Saturn¿s moon Enceladus.

This image was acquired in a viewing geometry that makes the tiny particles in the Enceladus plume easy to see.

This view was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 18, 2006, at a distance of approximately 930,000 kilometers (578,000 miles) from Enceladus and at a sun-Enceladus-spacecraft, or phase, angle of 154 degrees. Image scale is 6 kilometers (3 miles) per pixel.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Enceladus: Trailing Hemisphere

December 29, 2006

A variety of surface ages is revealed in this 16-image mosaic taken during Cassini's first close flyby of Enceladus, on Feb. 17, 2005.

This mosaic shows the trailing hemisphere of Enceladus -- the side of Enceladus that always faces away from the direction of the satellite's orbital motion. This hemisphere is dominated by Sarandib Planitia (just right of center), a region thought to be dominated by smooth plains in NASA Voyager 2 images taken in August 1981, but shown here in much higher resolution images to be covered in low ridges and troughs. Other major features seen in the region include Labtayt Sulci, a 1-kilometer- (0.6-mile-) deep canyon running northward from a cusp in the south polar terrain boundary (Cashmere Sulci) at lower right to a set of 1-kilometer-tall ridges (Cufa Dorsa and Ebony Dorsum) east of Sarandib Planitia (also seen in Enceladus Mosaic), as well as Samarkand Sulci, a band of ridges and troughs running along the western margin of Sarandib Planitia almost all the way north to Enceladus' north pole.

In contrast to the youthful terrain of Sarandib Planitia and the terrain south of it, the terrain north and west of Sarandib appears much older. These regions are covered with impact craters at various stages of degradation, either from viscous relaxation (which causes the craters to flatten over time), or from tectonic activity.

To create this single full-disk mosaic, the 16 images were reprojected into an orthographic projection centered at 2.3 degrees north latitude, 317.7 degrees west longitude with a pixel scale of 63 meters (207 feet) per pixel. The original images were taken by the Cassini spacecraft narrow-angle and wide-angle cameras from distances ranging from 10,850 to 29,750 kilometers (6,740 to 18,490 miles). The images had a phase, or sun-Enceladus-spacecraft, angle of 28 degrees.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Fractured World

December 29, 2006

Numerous blue-green fractures can be seen in this false-color mosaic taken during Cassini's second close flyby of Enceladus, on March 9, 2005.

The mosaic shows the anti-Saturnian hemisphere of Enceladus -- the side that always faces away from Saturn. This region contains a number of tectonic and impact features and shows how these two geologic forces interact on Enceladus. The center left portion of this mosaic is dominated by Diyar Planitia. Like Sarandib Planitia observed in the previous Enceladus flyby, the region is characterized by low ridges and troughs. Throughout this hemisphere, fractures of all sizes disrupt the previously existing cratered terrain and even the comparatively youthful Diyar Planitia.

Many of the younger fractures have blue-green walls, revealing coarse-grained water ice in the top layers of Enceladus' lithosphere, compared to the fine-grained ice that coats much of Enceladus' surface. The blue-green color is very similar to the coatings surrounding the south polar 'tiger stripes' (these appear greener than the features in the south polar mosaic released in 2005 (see Enceladus the Storyteller) due to the use of clear-filter images, instead of green, in that mosaic).

A higher resolution cropped section of this mosaic is available in Exploring Icy Canyons.

This mosaic consists of 25 false-color footprints (75 images total) taken by the Cassini spacecraft's narrow-angle camera. The mosaic uses an ultraviolet filter centered at 338 nanometers for blue, a green filter centered at 568 nanometers for green and a near-infrared filter centered at 930 nanometers for red--thus covering a wider spectrum region than the human eye. To create a single, full-disk mosaic, the images were reprojected into an orthographic projection centered at 1.5 degrees south latitude, 204 degrees west longitude with a pixel scale of 90 meters (295 feet) per pixel. The black strip seen at the top of the mosaic is an unfilled seam between two images.

The original images were taken from distances ranging from 4,300 to 31,800 kilometers (2,670 to 19,760 miles). The images have a phase, or sun-Enceladus-spacecraft, angle of 45 degrees.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Exploring Icy Canyons

December 29, 2006

Fine topographic detail and color variations are revealed in this 11-image, false color mosaic taken during Cassini's second close flyby of Saturn's moon Enceladus, on March 9, 2005.

This mosaic, a high-resolution cropped section of the full-disk mosaic available in Fractured World, shows the center of the anti-Saturnian hemisphere of Enceladus -- the side of Enceladus that always faces away from Saturn. The left portion of the mosaic is dominated by Diyar Planitia. Like Sarandib Planitia, observed in the previous Enceladus flyby of February 2005, the region is characterized by low ridges and troughs. Throughout this region, fractures of all sizes cut across Diyar Planitia and the older, cratered terrain at center and right.

Many of the younger fractures have blue-green walls, revealing coarse-grained water ice in the top layers of Enceladus' lithosphere, compared to the fine-grained ice that coats much of Enceladus' surface. The blue-green color is very similar to the coatings of the south polar "tiger stripes." The color here is greener than the features in the south polar mosaic released in 2005 (see Enceladus the Storyteller) due to the use of clear-filter images, instead of green, in the latter mosaic.

This mosaic consists of 11 false-color footprints (33 images total) taken by the Cassini spacecraft's narrow-angle camera. The mosaic uses an ultraviolet filter centered at 338 nanometers for blue, a green filter centered at 568 nanometers for green and a near-infrared filter centered at 930 nanometers for red, thus covering a wider spectrum region than the human eye. To create a single mosaic, the images were reprojected into an orthographic projection with a pixel scale of 45 meters per pixel. The region is centered at 3.9 degrees north latitude, 208.9 degrees west longitude and covers an area 233 kilometers (145 miles) by 154 kilometers (96 miles) in size.

The original images were taken by the Cassini spacecraft's narrow-angle camera from distances ranging from 4,300 to 27,050 kilometers (2,670 to 16,810 miles). The images have a phase, or sun-Enceladus-spacecraft, angle of 45 degrees. Image scale is 45 meters (150 feet) per pixel.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Brilliant Ice Dust

December 29, 2006

Lit by reflected light from Saturn, Enceladus appears to hover above the gleaming rings, its well-defined ice particle jets spraying a continuous hail of tiny ice grains. The fine particles coat the moon in a mantle as white as fresh snow and populate the torus, or doughnut-shaped E ring in which Enceladus resides.

Beyond Enceladus (505 kilometers, or 314 miles across), the fine particles in Saturn's other rings also glow brilliantly in scattered light in this viewing geometry. Running horizontally across the center of the image, between Enceladus and the dazzlingly bright F ring, are two faint rings--kin of the E ring. These are the G ring (top) and the recently discovered ring designated R/2006 S1 (bottom), which is also unofficially known as the Janus/Epimetheus ring.

This image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 22, 2006, at a distance of approximately 1.303 million kilometers (810,000 miles) from Enceladus and at a sun-Enceladus-spacecraft, or phase, angle of 160 degrees. Image scale is 8 kilometers (5 miles) per pixel.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

[Waspie_Dwarf]

Enceladus, A Moon of Saturn, is a "Cosmic Graffiti Artist," Astronomers Discover

The University of Virginia press release is reproduced below:

Feb. 8, 2007 -- Astronomers from the University of Virginia and other institutions have found that Enceladus, the sixth-largest moon of Saturn, is a “cosmic graffiti artist,” pelting the surfaces of at least 11 other moons of Saturn with ice particles sprayed from its spewing surface geysers. This ice sandblasts the other moons, creating a reflective surface that makes them among the brightest bodies in the solar system (Enceladus, itself a ball of mostly ice, is the single most reflective body in our solar system).

“Enceladus’ art is a work-in-progress, constantly altering the surfaces of other moons orbiting within this moon’s beautiful swirl of ice particles,” said Anne Verbiscer, a research scientist in the astronomy department at the University of Virginia and the study’s lead investigator. “We’ve dubbed Enceladus a graffiti artist because of its ability to alter the appearance of the other moons.”

A paper about her and her colleagues’ findings appears in the Feb. 9 issue of the journal Science.

The ring of ice particles Enceladus forms around Saturn is known as the E-ring. At least 11 other moons orbit within the E-ring and are constantly subjected to high velocity collisions with Enceladus’s icy wake.


Wispy fingers of bright, icy material reach
tens of thousands of kilometers outward from
Saturn's moon Enceladus into the E ring,
while the moon's active south polar jets
continue to fire away
Photo courtesy NASA/JPL/Space Science Institute



Anne Verbischer
Photo by Dan Addison
(click on photo for high res version)

A series of geysers at Enceladus’s south pole continually erupt, ejecting ice particles, spewing a swirling wispy trail in the moon’s wake and ultimately forming a cloudy ring of ice particles. The ring is added to over and over as Enceladus repeats its orbit. The particles may persist for thousands of years, until they collide with one of the embedded moons, including Enceladus as it flows through its own emissions.

“We asked ourselves why those other moons in the E ring are so bright, though they are not geologically active like Enceladus? The answer, we now know, is that the other moons are being ‘sand-blasted’, so to speak, by the ice particles ejected from Enceladus,” Verbiscer said. “These are physical characteristics not previously known.”

Verbiscer added that Enceladus is of great interest to astrobiologists who believe primitive microorganisms could, in theory, exist beneath the surface of that moon because of the existence of liquid water below the surface.

Planetary astronomers are particularly interested in Enceladus because of its geological activity. At 314 miles in diameter, Enceladus is nearly seven times smaller than the Earth’s moon. But unlike our moon, Enceladus is continually changing as its geysers spew ice and liquid water, the likely result of heat and pressure deep within.

The surface of Enceladus is quite young, possibly less than 100 million years. It is the sixth largest moon of the more than thirty known moons that orbit Saturn. Because of its icy surface, Enceladus has the highest albedo, or surface reflectivity of any body in the solar system. Astronomer William Herschel discovered the moon in 1789.

The satellite’s surface of ice includes smooth areas of plains, ice vents, ridges and long lines of cracks at its south pole. The cracks are the source of the ice plumes released from the body that escape into its orbit, trailing and accumulating in its path, creating a highly visible cloudy ring around Saturn.

Enceladus is named for a Roman and Greek mythological giant who was considered responsible for volcanic fires on Mt. Etna in Sicily. “That analogy certainly holds true with the realization that Enceladus is geologically active and spraying ice particles out of its south pole,” Verbiscer said. “But we’ve extended the gigantic influence that it has, because of its ability to alter the appearance of its neighboring moons.”

Verbiscer’s co-investigators are Richard French of Wellesley College, Mark Showalter of the SETI Institute and Paul Helfenstein of Cornell University.

Source: U.Va. Press Release

[Waspie_Dwarf]

Icy Outpost?

February 21, 2007

The Cassini spacecraft looks down under at the tortured south polar region of Enceladus, crossed by its "tiger stripes," or sulci, as the long, nearly parallel fractures are officially known. The use of enhanced color in this and other composite images makes the fractures and faults easier for the eye to detect.

The moon's excess warmth, water ice jets, and huge vapor plume laced with simple organic materials make it an excellent candidate for the search for pre-biotic chemistry, and possibly even life, beyond Earth. Enceladus is 505 kilometers (314 miles across).

This false-color view is a composite of images obtained using filters sensitive to ultraviolet, green and infrared light. The images were taken by the Cassini spacecraft narrow-angle camera on Jan. 16, 2007 at a distance of approximately 657,000 kilometers (408,000 miles) from Enceladus. Image scale is 4 kilometers (2 miles) per pixel.

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 mission for NASA\'s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini