Map of Dione - December 2006
December 29, 2006

This global digital map of Saturn's moon Dione was created using data taken by the Cassini spacecraft, with gaps in coverage filled in by NASA's Voyager spacecraft data. The map is an equidistant projection and has a scale of 400 meters (1,310 feet) per pixel. Equidistant projections preserve distances on a body, with some distortion of area and direction.

The mean radius of Dione used for projection of this map is 560 kilometers (348 miles).

This map is an update to the version released in December 2005. See Map of Dione - December 2005.

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

Map of Rhea - December 2006
December 29, 2006

This global digital map of Saturn's moon Rhea was created using data taken during NASA's Cassini and Voyager spacecraft flybys. The map is an equidistant projection and has a scale of 700 meters (2,300 feet) per pixel. Equidistant projections preserve distances on a body, with some distortion of area and direction.

The mean radius of Rhea used for projection of this map is 764 kilometers (475 miles).

This map is an update to the version released in December 2005. See Map of Rhea - December 2005.

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

Map of Tethys - December 2006
December 29, 2006

This global digital map of Saturn's moon Tethys was created using data taken by the Cassini spacecraft, with gaps in coverage filled in by NASA's Voyager spacecraft data. The map is an equidistant projection and has a scale of 300 meters (980 feet) per pixel. Equidistant projections preserve distances on a body, with some distortion of area and direction.

The mean radius of Tethys used for projection of this map is 533 kilometers (331 miles). This map is an update to the version released in December 2005. See Map of Tethys - December 2005.

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

Map of Mimas - December 2006
December 29, 2006

This global digital map of Saturn's moon Mimas was created using data taken by the Cassini spacecraft, with gaps in coverage filled in by NASA's Voyager spacecraft data. The map is an equidistant projection and has a scale of 400 meters (1,310 feet) per pixel. Equidistant projections preserve distances on a body, with some distortion of area and direction.

The mean radius of Mimas used for projection of this map is 198 kilometers (123 miles). This map is an update to the version released in December 2005. See Map of Mimas - December 2005.

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

13 June 2007

This is a compound image made from separate images of Saturn's two moons, Tethys (to the left) and Dione (to the right), taken by Cassini.

The two moons are flinging great streams of particles into space, according to data from the NASA/ESA/ASI Cassini mission to Saturn. The discovery suggests the possibility of some sort of geological activity, perhaps even volcanic, on these icy worlds.

The particles were traced to the two moons because of the dramatic movement of electrically charged gas in the magnetic environs of Saturn. Known as plasma, the gas is composed of negatively charged electrons and positively charged ions, which are atoms with one or more electrons missing. Because they are charged, the electrons and ions can get trapped inside a magnetic field.

Credits: NASA/ JPL

Saturn’s moons Tethys and Dione are flinging great streams of particles into space, according to data from the NASA/ESA/ASI Cassini mission to Saturn. The discovery suggests the possibility of some sort of geological activity, perhaps even volcanic, on these icy worlds.

The particles were traced to the two moons because of the dramatic movement of electrically charged gas in the magnetic environs of Saturn. Known as plasma, the gas is composed of negatively charged electrons and positively charged ions, which are atoms with one or more electrons missing. Because they are charged, the electrons and ions can get trapped inside a magnetic field.

Saturn rotates around itself in just 10 hours and 46 minutes. This sweeps the magnetic field and the trapped plasma through space. Just like a child on a fast-spinning merry-go-round, the trapped gas feels a force trying to throw it outwards, away from the centre of rotation.

The plasma tori of the two satellites are approximated in blue for Tethys (indicating lower energy plasma) and green for Dione (indicating higher energy plasma).

The orbit of Cassini is shown in black with red lines showing the positions of observed inward plasma injections. Butterfly electron pitch-angle distributions consistent with outward plasma flow are observed throughout the regions in between the inward injections.

Credits: SWRI (W. Lewis)

Soon after Cassini reached Saturn, in June 2004, it revealed that the planet’s hurried rotation squashes the plasma into a disc and that great fingers of gas are indeed being thrown out into space from the disc’s outer edges. Hotter, more tenuous plasma then rushes in to fill the gaps.

Now, Jim Burch of the Southwest Research Institute, USA, and colleagues have made a careful study of these events using the Cassini Plasma Spectrometer (CAPS). They have shown that the direction of the ejected electrons points back towards Tethys and Dione. “It establishes Tethys and Dione as important sources of plasma in Saturn’s magnetosphere,” says Burch.

Until this result, among Saturn’s inner moons only Enceladus was known to be an active world, with huge geysers spraying gases hundreds of kilometres above the moon’s surface. “This new result seems to be a strong indication that there is activity on Tethys and Dione as well,” says Andrew Coates from the Mullard Space Science Laboratory, University College London, and a collaborator on this latest work.

Plumes of icy material extend above the southern polar region of Saturn's moon Enceladus, as imaged by the Cassini spacecraft in January 2005. The monochrome view is presented along with a colour-coded image on the right. The view in this image is perpendicular to the tiger stripe fractures that straddle the south pole. Another plume view, was taken one month later and looks along the tiger stripe fractures. Images like these are being analyzed by scientists as they seek to explain the processes that could be producing such incredible features. As reported in the journal Science on 10 March 2006, imaging scientists believe that the plumes are geysers erupting from pressurized subsurface reservoirs of liquid water above 0°C.

These images were taken with the Cassini spacecraft narrow-angle camera at a distance of approximately 209 400 kilometres from Enceladus at a Sun-Enceladus-spacecraft, or phase, angle of 148 degrees. The image scale is about 1.3 kilometres per pixel.

The mosaic is an orthographic projection centred at 46.8 degrees south latitude, 188 degrees west longitude, and has an image scale of 67 metres per pixel. The original images ranged in resolution from 67 metres per pixel to 350 metres per pixel and were taken at distances ranging from 11 100 to 61 300 kilometres from Enceladus.

Credits: NASA/JPL/Space Science Institute

Activity is a draw for planetary scientists as it means that the planet has yet to reach equilibrium, or is perhaps being supplied with energy. The activity on Enceladus was detected first by Cassini's Dual Technique Magnetometer (MAG). This led the flight team to schedule a particularly close pass of Enceladus, which revealed a wealth of data about Enceladus’ alien geysers – and spectacular pictures, too.

“The best results arise when we combine a variety of data sets to understand the observations,” says Michele Dougherty, Imperial College, London, and Principal Investigator of MAG.

Magnificent blue and gold Saturn floats obliquely as one of its gravity-bound companions, Dione, hangs in the distance. The darkened rings seem to nearly touch their shadowy reverse images on the planet below.

This view looks toward the unlit side of the rings from about 9 degrees above the ring plane. The rings glow feebly in the scattered light that filters through them.

Dione is 1,126 kilometers (700 miles) across. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Feb. 4, 2007, at a distance of approximately 1.2 million kilometers (800,000 miles) from Saturn. Image scale is 75 kilometers (47 miles) per pixel.

Credits: NASA/JPL/Space Science Institute

In the case of Dione and Tethys, more fly-bys are scheduled in the future, which will allow the team and the other instruments a close-up look at the moons. Before that happens, the team has to go back and search for further signs of activity in the data already collected during the Tethys and Dione flybys of 2005.

In addition, Burch says that, having detected the electrons, they will now be on the lookout for the ions, so that the composition of the Tethys and Dione plasmas can be determined.


Notes

The findings will appear in the 14 June 2007 issue of the scientific journal Nature. The article, ‘Tethys and Dione as sources of outward-flowing plasma in Saturn’s magnetosphere’, is by J. Burch, J. Goldstein, W. Lewis, D. Young, A. Coates, M Dougherty and N. André.

The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency (ASI). The CAPS team, consisting of scientists from Europe and the US, is based at the Southwest Research Institute in San Antonio. The MAG team is based at Imperial College in London, and also consists of team members from the United States and several European countries.

Source: ESA - News

Tethys and Dione, side by side
June 13, 2007

Dione [dy-OH-nee] is the second densest moon of Saturn, after Titan. Dione is probably composed of a rocky core making up one-third of the moon's mass, and the rest is composed of water-ice. Dione is an icy body that is similar to Tethys.

Dione's icy surface includes heavily cratered terrain, with moderately and lightly cratered plains, as well as some severely cracked areas, with very bright material on the walls of the fractures. The heavily cratered terrain has numerous craters greater than 100 kilometers (about 62 miles) in diameter.

Tethys [TEE-thiss] lies in a part of the Saturnian system that was most likely once crowded with debris created by collisions between smaller and larger moons. Its icy surface is heavily cratered and contains faults in the ice that are probably a result of Tethys quakes at the times of some major impacts.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

July 4, 2007
(Source: Jet Propulsion Laboratory / Ames Research Center)

PASADENA, Calif. -- NASA's Cassini spacecraft has revealed for the first time surface details of Saturn's moon Hyperion, including cup-like craters filled with hydrocarbons that may indicate more widespread presence in our solar system of basic chemicals necessary for life.

Hyperion yielded some of its secrets to the battery of instruments aboard Cassini as the spacecraft flew close by in September 2005. Water and carbon dioxide ices were found, as well as dark material that fits the spectral profile of hydrocarbons.


The new composition map is overlaid onto
a previously released Cassini image of
Hyperion.

A paper appearing in the July 5 issue of Nature reports details of Hyperion's surface craters and composition observed during this flyby, including keys to understanding the moon's origin and evolution over 4.5 billion years. This is the first time scientists were able to map the surface material on Hyperion.


In this map, blue shows the maximum exposure
of frozen water, red denotes carbon dioxide
ice ("dry ice"), magenta indicates regions of
water plus carbon dioxide, yellow is a mix of
carbon dioxide and an unidentified material.

"Of special interest is the presence on Hyperion of hydrocarbons--combinations of carbon and hydrogen atoms that are found in comets, meteorites, and the dust in our galaxy," said Dale Cruikshank, a planetary scientist at NASA's Ames Research Center, Moffett Field, Calif., and the paper's lead author. "These molecules, when embedded in ice and exposed to ultraviolet light, form new molecules of biological significance. This doesn't mean that we have found life, but it is a further indication that the basic chemistry needed for life is widespread in the universe."

Cassini's ultraviolet imaging spectrograph and visual and infrared mapping spectrometer captured compositional variations in Hyperion's surface. These instruments, capable of mapping mineral and chemical features of the moon, sent back data confirming the presence of frozen water found by earlier ground-based observations, but also discovered solid carbon dioxide (dry ice) mixed in unexpected ways with the ordinary ice. Images of the brightest regions of Hyperion's surface show frozen water that is crystalline in form, like that found on Earth.

"Most of Hyperion's surface ice is a mix of frozen water and organic dust, but carbon dioxide ice is also prominent. The carbon dioxide is not pure, but is somehow chemically attached to other molecules," explained Cruikshank.


This new ultraviolet map (left) is shown
next to a previously released image of
Hyperion (right).

Prior spacecraft data from other moons of Saturn, as well as Jupiter's moons Ganymede and Callisto, suggest that the carbon dioxide molecule is "complexed," or attached with other surface material in multiple ways. "We think that ordinary carbon dioxide will evaporate from Saturn's moons over long periods of time," said Cruikshank, "but it appears to be much more stable when it is attached to other molecules."

"The Hyperion flyby was a fine example of Cassini's multi-wavelength capabilities. In this first-ever ultraviolet observation of Hyperion, the detection of water ice tells us about compositional differences of this bizarre body," said Amanda Hendrix, Cassini scientist on the ultraviolet imaging spectrograph at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Hyperion, Saturn's eighth largest moon, has a chaotic spin and orbits Saturn every 21 days. The July 5 issue of Nature also includes new findings from the imaging team about Hyperion's strange, spongy-looking appearance. Details are online at: http://ciclops.org/view.php?id=3303.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington.

More information on the Cassini mission is available at: http://www.nasa.gov/cassini.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Ruth Dasso Marlaire 650-604-4709
Ames Research Center, Moffett Field, Calif.


NEWS RELEASE: 2007-071

Source: NASA/JPL - Cassini - Press Release

MEDIA RELATIONS OFFICE
CASSINI IMAGING CENTRAL LABORATORY FOR OPERATIONS (CICLOPS)
SPACE SCIENCE INSTITUTE, BOULDER, COLORADO

Preston Dyches (720) 974-5859
CICLOPS/Space Science Institute, Boulder, Colo.

For Immediate Release: July 4, 2007

CASSINI SCIENTISTS WRING OUT THE DETAILS ON SPONGY HYPERION

Scientists on NASA’s Cassini mission to Saturn now have a better understanding of why the odd moon Hyperion has such an unusual appearance.

The crucial factor in creating the strange, sponge-like appearance of Hyperion appears to be its extremely low density, say Cassini scientists in a research paper being published in the July 5 issue of the journal Nature. The researchers examined Cassini spacecraft images and other data on the moon’s mass acquired during encounters with Hyperion over the past three years.

Hyperion is covered by a large number of medium-sized, well-preserved craters. “Careful mapping of features showed that its bizarre appearance probably results from a convergence of rather routine effects,” said Dr. Peter Thomas, a Cassini Imaging Team member working at Cornell University in Ithaca, New York.

Cassini’s closest encounter with Hyperion, in September 2005, allowed accurate measurement of the moon’s mass and size, which showed it is only slightly more than half as dense as water.

“The close flyby produced a tiny but measurable deflection of Cassini’s orbit. Therefore, the orbit determination, carried out by our Italian colleagues, allowed us to estimate the mass with fairly good accuracy,” said Cassini radio science deputy team leader Nicole Rappaport of the Jet Propulsion Laboratory in Pasadena, Calif. “Combined with the determination of Hyperion’s volume from imaging data, this provided an accurate computation of its density.”

Initial conjectures about the origin of Hyperion’s strange surface invoked dark materials accumulating on crater floors that subsequently got warmed by sunlight and melted deeper into the surface. However, the new analyses have shown that the moon’s low density, and therefore low surface gravity, may cause craters to form differently from those on other, denser bodies that have been explored in the Solar System.

According to the researchers, impactors smacking into Hyperion’s porous outer layers form craters more by compressing the surface than by blasting out material, as they do on denser bodies. Additionally, the moon’s low gravity means that any material ejected from craters on Hyperion has a good chance of escaping completely and not re-impacting the surface, making Hyperion’s craters look sharper and less blanketed by debris than on other bodies.

These new results about Hyperion’s craters accompany another paper in the same journal issue which details the moon’s composition. Both are important to understanding this unique moon's history and evolution. More information on the other paper can be found at http://saturn.jpl.nasa.gov.

“With time, we are coming to understand the various planetary processes that shape the bodies in our solar system,” said imaging team leader Carolyn Porco. “And this latest work on Hyperion is a beautiful demonstration of that.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo. The Cassini radio science instrument is distributed between the spacecraft and the stations of the Deep Space network. The elements of the radio science instrument onboard the spacecraft were developed via an international agreement between NASA and the Italian Space Agency.

-end-

Source: CICLOPS

Organics Sprinkled on Hyperion
July 4, 2007

Hyperion, the eighth largest of Saturn's nearly 60 known moons, is covered in craters and landslides. Sprinkled over the icy surface is a thin layer of organic dust, which has somehow been concentrated in the bottoms of some of the craters, forming a reddish black deposit.

This new color map shows the composition of a portion of Hyperion's surface determined with the Visual and Infrared Mapping Spectrometer aboard the Cassini spacecraft. The new composition map is overlaid onto a previously released Cassini image of Hyperion, taken with the Imaging Science Subsystem (see Cosmic Blasting Zone).

Blue shows the maximum exposure of frozen water, red denotes carbon dioxide ice ("dry ice"), magenta indicates regions of water plus carbon dioxide, yellow is a mix of carbon dioxide and an unidentified material.

Discovered in 1848, Hyperion held its secrets until the Cassini spacecraft flew close in September 2005, revealing its icy and organic composition. Hyperion is irregular in shape, tumbles chaotically, and takes 21 days to orbit Saturn. It is 300 kilometers (180 miles) in its longest dimension.

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 was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona, where this image was produced. 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/home/index.cfm. The visual and infrared mapping spectrometer team home page is at: http://wwwvims.lpl.arizona.edu. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/University of Arizona/Ames/Space Science Institute

Source: NASA/JPL - Cassini

Hyperion's Kaleidoscope of Color
July 4, 2007

This is a color map of the composition of a portion of Saturn's moon Hyperion's surface about 75 kilometers (45 miles) on a side.

In this map, blue shows the maximum exposure of frozen water, red denotes carbon dioxide ice ("dry ice"), magenta indicates regions of water plus carbon dioxide, yellow is a mix of carbon dioxide and an unidentified material. This map was made with data from the Visual and Infrared Mapping Spectrometer aboard the Cassini spacecraft during its flyby of Hyperion in September 2005.

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 was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona, where this image was produced.

For more information about the Cassini-Huygens mission, visit: http://saturn.jpl.nasa.gov/home/index.cfm. The visual and infrared mapping spectrometer team home page is at: http://wwwvims.lpl.arizona.edu.

Credit: NASA/JPL/University of Arizona/Ames

Source: NASA/JPL - Cassini

Hyperion's Icy Surface
July 4, 2007

In this ultraviolet image of Hyperion, produced using data taken with Cassini's Ultraviolet Imaging Spectrograph during the September 2005 close flyby, brightness contrasts are due to both topographic and compositional variations across the surface. The brightest regions are exposed water ice in the rim of the crater that dominates the hemisphere in view.

This new ultraviolet map (left) is shown next to a previously released image (right) taken by the Imaging Science Subsystem (see Cosmic Blasting Zone).

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 was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was designed and built at, and the team is based at the University of Colorado, Boulder. 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/home/index.cfm. The ultraviolet imaging spectrograph team home page is at: http://lasp.colorado.edu/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/University of Colorado/Space Science Institute

Source: NASA/JPL - Cassini

July 19, 2007
(Source: JPL)

Scientists have recently discovered that the planet Saturn is turning 60 -- not years, but moons.

"We detected the 60th moon orbiting Saturn using the Cassini spacecraft's powerful wide-angle camera," said Carl Murray, a Cassini imaging team scientist from Queen Mary, University of London. "I was looking at images of the region near the Saturnian moons Methone and Pallene and something caught my eye."

The newly discovered moon first appeared as a very faint dot in a series of images Cassini took of the Saturnian ring system on May 30 of this year. After the initial detection, Murray and fellow Cassini imaging scientists played interplanetary detective, searching for clues of the new moon in the voluminous library of Cassini images to date.


Initial calculations show the moon to have
a width of approximately 2 kilometers
(1.2 miles), with an orbit that lies between
those of the moons Methone and Pallene.

+ View QuickTime movie


The Cassini imaging team's legwork paid off. They were able to locate numerous additional detections, spanning from June 2004 to June 2007. "With these new data sets we were able to establish a good orbit for the new moon," said Murray. "Knowing where the moons are at all times is important to the Cassini mission for several reasons."

One of the most important reasons for Cassini to chronicle these previously unknown space rocks is so the spacecraft itself does not run into them. Another reason is each discovery helps provide a better understanding about how Saturn's ring system and all its billions upon billions of parts work and interact together. Finally, a discovery of a moon is important because with this new knowledge, the Cassini mission planners and science team can plan to perform science experiments during future observations if and when the opportunity presents itself.

What of this new, 60th discovered moon of Saturn? Cassini scientists believe "Frank" (the working name for the moon until another, perhaps, more appropriate one is found) is about 2 kilometers (1.2 miles) wide and, like so many of its neighbors, is made mostly of ice and rock. The moon's location in the Saturnian sky is between the orbits of Methone and Pallene. It is the fifth moon discovered by the Cassini imaging team.

"When the Cassini mission launched back in 1997, we knew of only 18 moons orbiting Saturn," said Murray. "Now, between Earth-based telescopes and Cassini we have more than tripled that number -- and each and every new discovery adds another piece to the puzzle and becomes another new world to explore."

Murray and his colleagues may get the chance to explore Saturn's 60th moon. The Cassini spacecraft's trajectory will put it within 11,700 kilometers (7,300 miles) in December of 2009.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Cassini-Huygens 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 team is based at the Space Science Institute, Boulder, Colo.

Related news releases:

+ Science and Technology Facilities Council

+ Cassini Imaging Team

Written by: DC Agle Media Contact: Carolina Martinez 818-354-9382

Source: NASA/JPL - Cassini - Press Release

Sixty for Saturn
July 19, 2007

The 60th moon of Saturn reveals itself in a sequence of images. The discovery suggests that the new moon, along with its neighbors Methone and Pallene (discovered by the Cassini imaging team in 2004), may form part of a larger group of moons in this region. The movie spans six hours.

Initial calculations show the moon to have a width of approximately 2 kilometers (1.2 miles), with an orbit that lies between those of the moons Methone and Pallene. The moon's orbit is in resonance with another moon, Mimas, also seen in this sequence as a very bright, moving object. The new moon's location is indicated by a red box.

The (narrow) ring visible in the images is the G ring, and the G ring arc passes through the field of view during the course of the movie. Calypso, a Trojan moon of Tethys, is also visible in the sequence. Trojan moons are found near gravitationally stable points ahead or behind a larger moon.

This view looks toward the non-illuminated side of the rings from about 3 degrees above the ringplane.

The series of images was taken in visible light with the Cassini spacecraft wide-angle camera on May 30, 2007, at a distance of approximately 1.76 million kilometers (1.09 million miles) from Saturn. Image scale is about 105 kilometers (65 miles) per pixel. The ghostly shape that stretches across the scene results from scattered light within the camera optics.

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

Saturn has to many moons. I don't know all the names of them. Thanks for this.

Not all of them have been named yet, although they will be eventually.

From the NASA/JPL Cassini site page on Saturn's moons:

The site gives more details on the moons and can be found here: NASA/JPL - Cassini - Moons.

60 moons!

Now you see Saturn is just being greedy, it should make do with just one moon like we have to

Oh okay. I wasn't completely sure about that. Thanks!

Lotus: Yes. It is being greedy.

Rhea's Pop-up Crater
October 15, 2007

Rhea's surface gains some depth in this stereo image, or anaglyph, which features the bright and geologically young-looking rayed crater on the moon's leading hemisphere. The view was created from images taken during Cassini's close encounter with Rhea (1,528 kilometers, or 949 miles across) on Aug. 30, 2007.

The crater is 48 kilometers (30 miles) wide, and its rays extend several hundred kilometers outward. The rim of this crater is quite sharply defined, and there are few small craters overprinted onto it. These characteristics, along with the brightness of the crater and its rays are indicative of a feature formed relatively recently in geologic history.

The hummocky floor of the crater possesses a central peak and clusters of small craters. The little craters may be secondary impact sites, formed by ejecta from the primary impact that landed in the crater, or they could have been formed by material that had broken off of the body that struck Rhea.

For an even higher resolution view of this feature, see Catch That Crater.

This stereo image is a mosaic consisting of seven Cassini spacecraft narrow-angle camera images. The view is an orthographic projection centered on 12 degrees south latitude, 112 degrees west longitude and has a resolution of 45 meters (148 feet) per pixel. An orthographic view is most like the view seen by a distant observer looking through a telescope. North is up.

The clear filter images for this stereo image were taken from distances ranging from about 17,000 kilometers (10,600 miles, for the red-colored image) to 7,500 kilometers (4,700 miles, for the blue/green-colored image) from Rhea.

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

December 6, 2007
(Source: Jet Propulsion Laboratory/Space Science Institute)

Imaging scientists on NASA's Cassini mission are telling a tale of how the small moons orbiting near the outer rings of Saturn came to be. The moons began as leftover shards from larger bodies that broke apart and filled out their "figures" with the debris that made the rings.

It has long been suspected that Saturn's rings formed in the disintegration of one or several large icy bodies, perhaps pre-existing moons, by giant impacts. The resulting debris quickly spread and settled into the equatorial plane to form a thin disk surrounding the planet. And the small, irregularly shaped ring-region moons were believed to be the leftover pieces from this breakup.


These high resolution images of Pan and Atlas
reveal distinctive "flying saucer" shapes created
by prominent equatorial ridges not seen on the
other small moons of Saturn.
----------------------------------------------------

Now, several years' worth of cosmic images of Saturn's 14 known small moons have been used to derive the sizes and shapes of most of them, and in about half the cases, even masses and densities. This information, published in the Dec. 7 issue of the journal Science, has led to new insights into how some of these moons may have formed.

The tip-off was the very low density of the inner moons, about half that of pure water ice, and sizes and shapes that suggested they have grown by the accumulation of ring material. The trouble was, these moons are within and near the rings, where it is not possible for small particles to fuse together gravitationally. So how did they do it? They got a jump start.


Saturn's moon Janus (near side of the rings)
and Prometheus (far side). The image shows
that Prometheus is more elongated than Janus.
----------------------------------------------------

"We think the only way these moons could have reached the sizes they are now, in the ring environment as we now know it to be, was to start off with a massive core to which the smaller, more porous ring particles could easily become bound," said Carolyn Porco, Cassini imaging team leader from the Space Science Institute in Boulder, Colo. Porco is the lead author of the first of two related articles published in this week's issue of Science.

Simple calculations and more complicated computer simulations have shown that ring particles will readily become bound to a larger seed having the density of water ice. By this process, a moon will grow even if it is relatively close to Saturn. The result is a ring-region moon about two to three times the size of its dense ice core, covered with a thick shell of porous, icy ring material. To make a 30-kilometer moon (19 miles) requires a seed of about 10 kilometers (6 miles).

Where did such large cores come from? And when did this all take place?

"The core may in fact be one of the remnants from the original ring-forming event,¿ said co-author Derek Richardson, professor of astronomy at the University of Maryland, College Park, ¿which might have been left intact all this time and protected from additional collisional breakup by the mantle of ring particles around it."

Just exactly when the rings formed is not known. "But it is not out of the question that the moons date back to the time of ring formation," said Porco.

The researchers show that the cores of Pan and Daphnis, which orbit within gaps in the outer A ring, were large enough to open narrow gaps. Accretion, or accumulation of material, they say, probably occurred quickly. The moons grew and their gaps widened, achieving their present sizes before the gaps were completely emptied of material, and probably before the local rings reached their present thickness.

So how did Pan in the main rings, and Atlas, which orbits just beyond the outer edge of the main rings, get the prominent equatorial ridges that make them look like flying saucers? The second paper reports evidence for a secondary stage of accretion that occurred after the moons' growth was completed and after the rings flattened to their present 20-meter (66 feet) thickness.

"Our computer simulations show that the ridges must have accreted rapidly when Saturn's rings were thin, forming small accretion disks around the equators of Pan and Atlas," said Sebastien Charnoz, lead author and an associate of imaging team member Andre Brahic at the University Paris-Diderot and CEA Saclay, in France. "The ridges might be the remains of 'fossilized' accretion disks, fundamental structures seen at all scales in the universe, from planetary rings to galaxies."

Images of Saturn's small moons are available at: _http://saturn.jpl.nasa.gov and _http://www.nasa.gov/cassini and _http://ciclops.org. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini 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 team is based at the Space Science Institute, Boulder, Colo.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
carolina.martinez@jpl.nasa.gov

Preston Dyches 720-974-5859
Space Science Institute, Boulder, Colo.
media@ciclops.org

NEWS RELEASE: 2007-142

Source: NASA/JPL - Cassini - News Release

Saturn's Saucer Moons
December 6, 2007

The highest resolution images of Pan and Atlas reveal distinctive "flying saucer" shapes created by prominent equatorial ridges not seen on the other small moons of Saturn.

From left to right: a view of Atlas' trailing hemisphere, with north up, at a spatial scale of about 1 kilometer (0.6 mile) per pixel; Atlas seen at about 250 meters (820 feet) per pixel from mid-southern latitudes, with the sub-Saturn hemisphere at the top and leading hemisphere to the left; Pan's trailing hemisphere seen at about 3 kilometers (2 miles) per pixel from low southern latitudes; an equatorial view, with Saturn in the background, of Pan's anti-Saturn hemisphere at about 1 kilometer (0.6 mile) per pixel.

On Atlas, the ridge extends 20 to 30 degrees in latitude on either side of the equator; on Pan, its latitudinal extent is 15 to 20 degrees. Atlas shows more asymmetry than Pan in having a more rounded ridge in the leading and sub-Saturn quadrants.

The heights of the ridges can be crudely estimated by assuming (ellipsoidal) shapes that lack ridges and vary smoothly cross the equator. Heights of Atlas' ridge range from about 3 kilometers (2 miles) at 270 degrees west longitude to 5 kilometers (3 miles) at 180 and 0 degrees. Pan's ridge reaches about 4 kilometers (2.5 miles) at 0 degrees west longitude, and is about 1.5 kilometers (0.9 mile) high over most of the rest of the equator.

The ridges represent about 27 percent of Atlas' volume and 10 percent of Pan's volume.

The images were acquired with the Cassini spacecraft narrow-angle camera between 2005 and 2007. Pan is 33 kilometers (20.5 miles) across at its equator and 21 kilometers (13 miles) across at its poles; Atlas is 39 kilometers (24 miles) across at its equator and 18 kilometers (11 miles) across at its poles.

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

February 19, 2008
(Source: Jet Propulsion Laboratory)

Despite the incredible diversity of Saturn's icy moons, theirs is a story of great interaction. Some of them are pock-marked, some seemingly dirty, others pristine, one spongy, one two-faced, some still spewing with activity and some seeming to be captured from the far reaches of the solar system. Yet many of them have a common thread -- black "stuff" coating their surfaces.


This collage showcases several of Saturn's
moons.
----------------------------------------------------

"We are beginning to unravel the mysteries of these different and strange moons," said Rosaly Lopes, Cassini scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. She coordinated a special section of 14 papers about Saturn's icy moons that appears in the February issue of the journal Icarus. Taken together, the papers bring an idea that Cassini scientist Bonnie Buratti calls "the ecology of the Saturn system" to the forefront. "Ecology is about your entire environment -- not just one body, but how they all interact," said Buratti. "The Saturn system is really interesting, and if you look at the surfaces of the moons, they seem to be altered in ways that aren't intrinsic to them. There seems to be some transport in this system."

Though the details of that transport are not yet clear, mounting evidence suggests that some mechanism has spread the mysterious dark material found on several of the moons from one to another; the material may even have a common cometary origin. Along those lines, several of the new papers focus on similarities between the dark material found on different moons -- on Hyperion and Iapetus, for example, or between Phoebe and Iapetus.

Roger Clark of the U.S. Geological Survey in Denver goes further, saying, "We see the same spectral signature on all the moons that have coatings of dark material." Clark is lead author of one of the new papers, which focuses on Saturn's moon Dione. His team found the dark material there to be extremely fine-grained, making up only a very thin layer on the moon's trailing side. Its distribution and composition, as measured by the Cassini visual and infrared mapping spectrometer, indicate that the dark material is not native to Dione. And scientists see many of the same signatures there that appear on the moons Phoebe, Iapetus, Hyperion and Epimetheus, and also in Saturn's F-ring.

As for where this material comes from and what the dark material is, Clark said, "It's a mystery, which makes it intriguing. We're still trying to find the exact match." The visual and infrared spectrometer detected unique absorption bands in the dark material within the Saturn system, which scientists have not seen anywhere else in the solar system. "The data keep getting better and better," he said. "We're ruling things out and figuring out pieces." So far, the team has identified bound water and, possibly, ammonia in the dark material.

Ongoing geologic activity is another component of Saturn's ecology as some of the moons continue to feed the planet's rings, which in turn affect many of the moons.

Clark's team reports tentative evidence to support the hypothesis presented earlier this year that Dione is still geologically active. In one series of observations, the infrared spectrometer detected a cloud of methane and water ice encircling Dione in its orbit within the outer portions of Saturn's E-ring.

Of course the big story is the icy plumes spewing from the warm, south polar region of Enceladus. These plumes are believed to be feeding the E-ring. A paper led by Frank Postberg of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, says there are traces of organic compounds or silicate materials within the water ice-dominated E-ring, close to Enceladus. This implies that the moon's rocky core and liquid water are dynamically interacting. The finding could bolster a theory that Dennis Matson and Julie Castillo of JPL put forth this year, which said that a warm, organic brew might lie just below Enceladus' surface.

Cassini's next close study of an icy moon is the highly-anticipated flyby of Enceladus scheduled for March 12. During that flyby, Cassini will pass by the active moon at a distance of only 50 kilometers (30 miles) at its point of closest approach, and at a distance of around 200 kilometers (120 miles) when it passes through the plumes.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

carolina.martinez@jpl.nasa.gov

Source: NASA/JPL - Cassini - News Release

Several of Saturn's moons
February 19, 2008

This collage showcases several of Saturn's moons.

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

Map of Tethys - February 2008
February 20, 2008

This global map of Saturn's moon Tethys was created using images taken during Cassini spacecraft flybys, with Voyager images filling in the gaps in Cassini's coverage.
The map is an equidistant projection and has a scale of 292.5 meters (959.6 feet) per pixel. The mean radius of Tethys used for projection of this map is 536.3 kilometers (333.2 miles). The resolution of the map is 32 pixels per degree. This updated map has been shifted east by 1.5 degrees of longitude, compared to the previously released Cassini product (see Map of Tethys - December 2006), in order to conform to the International Astronomical Union longitude system convention for Tethys.

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

Map of Dione - May 2008
May 20, 2008

This global map of Saturn's moon Dione was created using images taken during Cassini spacecraft flybys, with Voyager images filling in the gaps in Cassini's coverage.

An extensive system of bright ice cliffs created by tectonic fractures adorns the moon's trailing hemisphere.

The map is a simple cylindrical (equidistant) projection and has a scale of 614 meters (2,014 feet) per pixel at the equator. The mean radius of Dione used for projection of this map is 562 kilometers (349 miles). This updated map has been shifted west by 0.6 degrees of longitude, compared to the previously released Cassini product Map of Dione - December 2006, in order to conform to the International Astronomical Union longitude system convention for Dione.

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

My favorite Saturn moon is Titan. I saw the PBS TV show on the space probe that passed by Saturn's rings and Titan.
Amazing pictures that were much better than the last space probe decades ago.

Titan is such a complex world and we have learned so much about it in recent years that it has a topic all of its own. You can find it here: Exploration of Titan

The Voyagers flew past in 1980 and 81. They passed trough the Saturnian system rather than go into orbit there (Voyager 2 also flew past Uranus and Neptune). These amazing spacecraft taught us a huge amount about the outer solar system Cassini-Huygens (and Galileo at Jupiter) have built on the knowledge they provided. The Voyagers were probably one of NASA's mankind's finest achievements in robotic exploration.

Thanks for the link. This should keep me busy for a while!