ESA Cassini Image: Scrambling Saturn’s B-ring

Clumpy particles in Saturn’s B-ring provide stark contrast to the delicately ordered ringlets seen in the rest of this view presented by the Cassini spacecraft.

Saturn’s B-ring is the largest and brightest of the gas giant’s rings, the outer portion of which is seen in the left side of this image.

The ring’s outside edge is influenced by meddling moon Mimas, which orbits the planet once for every two circuits the icy ring particles complete.

These periodic gravity perturbations are thought to compress the ring particles into clumps, while maintaining the ring’s well-defined outer edge.

Beyond the B-ring lies the Huygens gap, the widest dark void visible in this image, punctuated only by the bright Huygens ringlet.

Saturn's Moon Mimas

The 4800 km-wide Cassini Division separates the B-ring from the outermost A-ring, but itself is marked out with faint, concentric strands of ring material.

From Earth, the Cassini Division appears as a thin black gap in Saturn’s rings, but close-up views from spacecraft expose the delicate structures in fine detail.

This image was taken in visible light with the Cassini spacecraft narrow-angle camera on 10 July 2009 from a distance of 320 000 km from Saturn.

Cassini is a joint mission between ESA, NASA and ASI and has been in orbit around Saturn since 2004. It is now in its second extended mission phase, the Cassini Solstice Mission, which will continue until 2017.

NASA Cassini Image: Saturn

Flying over the unlit side of Saturn's rings, the Cassini spacecraft captures Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green, while the planet's shadow casts a wide net on the rings.

ESA Saturn Titan: Far-off cousin of part-time African lake found on Titan

A region on Saturn’s moon Titan has been found to be similar to the Etosha Pan in Namibia, Africa. Both are ephemeral lakes – large, shallow depressions that sometimes fill with liquid.

Ontario Lacus is the largest lake in the southern hemisphere of Saturn’s moon, Titan. It is a little smaller than its namesake, Lake Ontario in North America, but otherwise differs from it in some major ways.

It is filled with liquid hydrocarbons, not water, and it is only a few metres deep at most, located in an extremely shallow depression in a flat sedimentary basin, surrounded by small mountain ranges.

In addition, a new study shows that these landforms and the climatic conditions in the region are similar to those of semi-arid regions on Earth, such as the salt pans of southern Africa.

The observations were made by the Cassini orbiter, part of the NASA, ESA and Italian Space Agency Cassini–Huygens mission to Saturn’s system.

While Ontario Lacus was previously thought to be permanently filled with liquid methane, ethane and propane, these latest observations, published in the journal Icarus, suggest otherwise.

By combining data from Cassini’s imaging, spectroscopic and radar instruments – each of which observed Ontario Lacus twice – scientists led by Thomas Cornet of the Université de Nantes, France, found evidence for channels etched into the lake bed within the southern boundary of the depression. These channels remained visible between December 2007 and January 2010, each time the spatial resolution was able to resolve them.

“We conclude that the solid floor of Ontario Lacus is most probably exposed in those areas,” says Cornet.

In addition, Cassini shows sediments around Ontario Lacus that also indicate the liquid level has been higher in the past.

This is similar to ephemeral lakes on Earth. The researchers suggest its nearest cousin is the Etosha Pan in Namibia. This salt lake bed fills with a shallow layer water, provided by the rise of the underground aquifer during the rainy season, before evaporating to leave sediments like tide marks showing the previous extent of the water.

Cornet and colleagues thus believe that Ontario Lacus is also the result of subsurface hydrocarbon fluids occasionally welling up and flooding the depression, before then partially drying out again.

Beyond Earth, Titan is the only other world known to bear stable liquids on its surface. Where Earth has a water cycle, Titan has a full hydrocarbon cycle, based on hydrogen, carbon and nitrogen, taking place between the atmosphere, the surface and the subsurface. Titan’s lakes are an integral part of this process.

“These results emphasise the importance of comparative planetology in modern planetary sciences: finding familiar geological features on alien worlds like Titan allows us to test the theories explaining their formation,” says Nicolas Altobelli, ESA’s Cassini–Huygens project scientist.

NASA Cassini Successfully Flies over Enceladus

 This image was taken by NASA's Cassini spacecraft on April 14, 2012. The camera was pointing toward TETHYS at approximately 10,875 miles (17,502 kilometers) away. Image Credit: NASA/JPL/Space Science Institute.

These raw, unprocessed images of Saturn's moons Enceladus and Tethys were taken on April 14, 2012, by NASA's Cassini spacecraft.

Cassini flew by Enceladus at an altitude of about 46 miles (74 kilometers).

This flyby was designed primarily for the ion and neutral mass spectrometer to analyze, or "taste," the composition of the moon's south polar plume as the spacecraft flew through it.

These raw, unprocessed images of Saturn's moons Enceladus and Tethys were taken on April 14, 2012, by NASA's Cassini spacecraft.

Cassini flew by Enceladus at an altitude of about 46 miles (74 kilometers). This flyby was designed primarily for the ion and neutral mass spectrometer to analyze, or "taste," the composition of the moon's south polar plume as the spacecraft flew through it.

Cassini's path took it along the length of Baghdad Sulcus, one of Enceladus' "tiger stripe" fractures from which jets of water ice, water vapor and organic compounds spray into space. At this time, Baghdad Sulcus is in darkness, but that was not an obstacle for another instrument, the composite infrared spectrometer, which can see features by their surface temperatures and which also took measurements during this flyby.

As soon as daylight passed into the spacecraft's remote sensing instruments' line of sight, Cassini's cameras acquired images of the surface.

The wide-angle-camera image included in the new batch, taken from around the time of closest approach, has some smearing from the movement of the spacecraft during the exposure, but still shows the surface in vivid detail.

Cassini's cameras also imaged Enceladus' south polar plume at a high phase angle as the satellite appeared as a thin crescent and the plume was backlit.

After the Enceladus encounter, Cassini passed the moon Tethys with a closest approach distance of about 5,700 miles (9,100 kilometers). This was Cassini's best imaging encounter with Tethys since a targeted encounter in September 2005.

The 2005 encounter, with a closest approach distance of about 930 miles (1,500 kilometers), provided the images of Tethys with the best resolution and captured views of the side of Tethys that faces Saturn in its orbit.

This new encounter examined the opposite side of Tethys, providing some of the highest-resolution images of the side that faces away from Saturn. Cassini acquired a 22-frame mosaic of this side, which features the large impact basin named Odysseus.

Scientists will use these new data in conjunction with images from previous encounters to create digital elevation maps of the moon's surface.

NASA CASSINI Image: Saturn's Moon Enceladus - Plume of Water Ice

Below a darkened Enceladus, a plume of water ice is backlit in this view of one of Saturn's most dramatic moons.

Dramatic plumes, both large and small, spray water ice from many locations along the moon's famed "tiger stripes" near the south pole of Enceladus. 

The tiger stripes are fissures that spray icy particles, water vapour and organic compounds.

The terrain seen here is on the leading hemisphere of Enceladus (313 miles, or 504 kilometers across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 20, 2012. 

The view was acquired at a distance of approximately 83,000 miles (134,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 165 degrees. Image scale is 2,628 feet (801 meters) per pixel.

Image credit: NASA/JPL-Caltech/Space Science Institute

NASA Cassini: Sharper image of Saturn moon Rhea

This photo made March 10, 2012, by NASA's Cassini spacecraft shows a raw, unprocessed image of Saturn's moon Rhea. 

The camera was pointing toward Rhea from a distance of approximately 42,096 kilometers (26,157 miles). 

(AP Photo/NASA/JPL-Caltech/SSI)

The pockmarked surface of Saturn's second-largest moon has come into sharper focus in new images released by Nasa.

The space agency released the new views of the moon Rhea, which were captured by the international Cassini spacecraft during a recent fly-by.

One of its cameras spied two huge impact basins and other geologic features on Rhea's icy surface from 26,000 miles away last week.

Cassini, funded by Nasa and the European and Italian space agencies, was launched in 1997. It reached Saturn in 2004 and has been studying the ringed planet and its numerous moons.

NASA Cassini Image: Saturn's Moon Mimas - Cut-Off Rings

Image credit: NASA/JPL-Caltech/Space Science Institute

One of Saturn's moons, Mimas joins the planet's rings which appear truncated by the planet's shadow in this Cassini spacecraft image.

Saturn is off to the left, out of view here.

The inner rings are just visible there but the planet's shadow covers part of the rings across the middle of the image.

Mimas (246 miles, or 396 kilometers across) is closer to Cassini than the rings are here.

The bright speck above the rings is a star.

To increase visibility, the rings have been brightened by a factor of two relative to Mimas. This view looks toward the southern, un-illuminated side of the rings from just below the ring-plane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 21, 2011.

The view was obtained at a distance of approximately 1.7 million miles (2.7 million kilometers) from Mimas. Image scale is 10 miles (16 kilometers) per pixel on Mimas.



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 www.nasa.gov/cassini and saturn.jpl.nasa.gov . The Cassini imaging team homepage is at ciclops.org

NASA Cassini Image: Saturn's Moons Tethys and Titan

This NASA image shows the line of Saturn's rings as they disrupt the Cassini spacecraft's view of the moons Tethys and Titan.

Larger Titan (3,200 miles, or 5,150 kilometres across) is on the left. Tethys (660 miles, or 1,062 kilometres across) is near the centre of the image.

Picture: NASA/AFP/Getty

NASA Cassini to make a double pass at Saturn's Moons, Dione and Titan

A quartet of Saturn's moons, from tiny to huge, surround and are embedded within the planet's rings in this Cassini composition. Credit: NASA/JPL-Caltech/Space Science Institute

The closest approach to Dione, about 61 miles (99 kilometers) above the surface, will take place at about 1:39 a.m. PST (4:39 a.m. EST) on Dec. 12.

One of the questions Cassini scientists will be asking during this flyby is whether Dione's surface shows any signs of activity.


Understanding Dione's internal structure will help address that question, so Cassini's radio science instrument will learn how highly structured the moon's interior is by measuring variations in the moon's gravitational tug on the spacecraft.

The composite infrared spectrometer instrument will also look for heat emissions along fractures on the moon's surface.

Cassini will also be probing whether Dione, like another Saturnian moon, Rhea, has a tenuous atmosphere.

Scientists expect a Dionean atmosphere - if there is one - to be much more ethereal than even Rhea's.


Research published in journal Geophysical Research Letters and led by Sven Simon, a Cassini magnetometer team member at the University of Cologne, Germany, found magnetic field disturbances around Dione, hinting at a tenuous atmosphere.

But scientists hope to get stronger confirmation by "tasting" the space around the moon with Cassini's ion and neutral mass spectrometer.

On Cassini's journey out from Dione toward Titan, the imaging science subsystem will turn back to look at Dione's distinctive, wispy fractures and a ridge called Janiculum Dorsa.

Cassini will approach within about 2,200 milles (3,600 kilometers) of the Titan surface, at about 12:11 p.m. PST (3:11 PM EST) on Dec. 13.

At Titan, the composite infrared spectrometer will be making measurements to understand how the seasonal transition from spring to summer affects wind patterns in the atmosphere near Titan's north pole. It will also search for mist.

The visual and infrared mapping spectrometer and imaging science subsystem will be observing the same equatorial deserts where the imaging science subsystem saw sudden and dramatic surface changes last year, when Titan was experiencing early northern spring.

One possibly theory is that rainstorms caused these changes. As Cassini recedes from Titan, the imaging cameras will also continue to observe the moon for another day to monitor any new weather systems.

NASA Cassini Image: Ethereal Atmosphere of Rhea

NASA's Cassini spacecraft has detected a very tenuous atmosphere known as an exosphere, infused with oxygen and carbon dioxide around Saturn's icy moon Rhea.

This is the first time a spacecraft has directly captured molecules of an oxygen atmosphere – albeit a very thin one -- at a world other than Earth.

The oxygen appears to arise when Saturn's magnetic field rotates over Rhea.

Energetic particles trapped in the planet's magnetic field pepper the moon’s water-ice surface. They cause chemical reactions that decompose the surface and release oxygen. The source of the carbon dioxide is less certain.

Oxygen at Rhea's surface is estimated to be about 5 trillion times less dense than what we have at Earth. But the new results show that surface decomposition could contribute abundant molecules of oxygen, leading to surface densities roughly 100 times greater than the exospheres of either Earth's moon or Mercury.

The formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.

"The new results suggest that active, complex chemistry involving oxygen may be quite common throughout the solar system and even our universe," said lead author Ben Teolis, a Cassini team scientist based at Southwest Research Institute in San Antonio.

"Such chemistry could be a prerequisite for life. All evidence from Cassini indicates that Rhea is too cold and devoid of the liquid water necessary for life as we know it."

Releasing oxygen through surface irradiation could help generate conditions favorable for life at an icy body other than Rhea that has liquid water under the surface, Teolis said.

If the oxygen and carbon dioxide from the surface could somehow get transported down to a sub-surface ocean, that would provide a much more hospitable environment for more complex compounds and life to form.

Scientists are keen to investigate whether life on icy moons with an ocean is possible, though they have not yet detected it.

The tenuous atmosphere with oxygen and carbon dioxide makes Rhea, Saturn's second largest moon, unique in the Saturnian system. Titan has a thick nitrogen-methane atmosphere, but very little carbon dioxide and oxygen.

"Rhea is turning out to be much more interesting than we had imagined," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"The Cassini finding highlights the rich diversity of Saturn’s moons and gives us clues on how they formed and evolved."

NASA Cassini Double Play: Enceladus And Titan

On the left, Saturn's moon Enceladus is backlit by the sun, showing the fountain-like sources of the fine spray of material that towers over the south polar region.

On the right, is a composite image of Titan. Image credit: NASA/JPL/SSI and NASA/JPL/University of Arizona

About a month and a half after its last double flyby, NASA's Cassini spacecraft will be turning another double play this week, visiting the geyser moon Enceladus and the hazy moon Titan.

The alignment of the moons means that Cassini can catch glimpses of these two contrasting worlds within less than 48 hours, with no detours in between.

Cassini will make its closest approach to Enceladus late at night on May 17 Pacific time, which is in the early hours of May 18 UTC. The spacecraft will pass within about 435 kilometers (270 miles) of the moon's surface.

The main scientific goal at Enceladus will be to watch the sun play peekaboo behind the water-rich plume emanating from the moon's south polar region. Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume.

Ammonia has already been detected in the plume and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon's interior.

The second of Cassini's two flybys is an encounter with Titan. The closest approach will take place in the late evening May 19 Pacific time, which is in the early hours of May 20 UTC. The spacecraft will fly to within 1,400 kilometers (750 miles) of the surface.

Cassini will primarily be doing radio science during this pass to detect the subtle variations in the gravitational tug on the spacecraft by Titan, which is 25 percent larger in volume than the planet Mercury.

Analyzing the data will help scientists learn whether Titan has a liquid ocean under its surface and get a better picture of its internal structure. The composite infrared spectrometer will also get its southernmost pass for thermal data to fill out its temperature map of the smoggy moon.

Cassini has made four previous double flybys and one more is planned in the years ahead.

NASA Cassini Cruises By Rhea And Helene

Cassini's closest-ever flyby of Saturn's moon Rhea went quite smoothly and teams are busy checking out their data! These flybys never fail to amaze me. And the raw images - which give us an unprocessed first look - are really cool!

Raw image N00152150 gives us a view of part of the bright, fractured terrain we refer to as "wispy terrain" from about 14,000 kilometers (8,900 miles) away.

We know that Rhea's albedo overall is quite high. (When I say "albedo," I basically mean "brightness" or "reflectivity." Studying the albedo can tell a lot about surface composition, geologic processes, and interactions with external environment.)

But this image demonstrates how bright these cracks are since they are so shiny that the surrounding terrain looks quite dark. There are also some interesting apparent albedo variations seen in this image, which are really intriguing.

This raw image (N00152175) from Cassini's narrow-angle camera image was taken about 40 minutes after closest approach. The image shows a region adjacent to the wispy terrain -craters, craters everywhere! And those crater rims bright compared to the surrounding terrain.

NASA, ESA Cassini Fly-by: Titan's Cool and Sluggish Interior

This artist's illustration shows the likely interior structure of Saturn's moon Titan deduced from gravity field data collected by NASA's Cassini spacecraft.

The investigation by Cassini's radio science team suggests that Titan's interior is a cool mix of ice studded with rock, though the outermost 500 kilometers (300 miles) appear to be ice essentially devoid of any rock.

Many planets and moons, including the Earth, evolve into a body with a clearly distinct rocky core. This radio science investigation suggests Titan's interior, cool and sluggish, failed to allow the interior to separate into completely differentiated layers of ice and rock.

In addition to the hazy surface of Titan (yellow), the layers in the cutaway show an ice layer starting near the surface (light gray), an internal ocean hypothesized from other Cassini data (blue), another layer of ice (light gray) and the mix of rock and ice in the interior (dark gray). In the background are the Cassini spacecraft and Saturn, not to scale.

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 project for NASA's Science Mission Directorate in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. Cassini's radio science subsystem has been jointly developed by NASA and the Italian Space Agency.

For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov/.

Image credit: NASA/JPL