NASA Mars Orbiter Views Opportunity Rover on Ridge

NASA - Mars Reconnaissance Orbiter (MRO) patch / NASA - Mars Science Laboratory (MSL) patch.

February 19, 2014

Opportunity Rover on 'Murray Ridge' Seen From Orbit

Image above: The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter caught this view of NASA's Mars Exploration Rover Opportunity on Feb. 14, 2014. The red arrow points to Opportunity at the center of the image.

A new image from a telescopic camera orbiting Mars shows NASA's Mars Exploration Rover Opportunity at work on "Murray Ridge," without any new impact craters nearby.

The Feb. 14 view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter is available online at http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA17941.  Rover tracks from Opportunity, as well as the rover itself, are visible.

A rock, dubbed "Pinnacle Island," appeared in January 2014 next to Opportunity where it had been absent a few days earlier. After that, researchers using HiRISE planned this observation to check the remote possibility that a fresh impact by an object from space might have excavated a crater near Opportunity and thrown this rock to its new location. No fresh impact site is seen in the image. Meanwhile, observations by the rover solved the Pinnacle Island mystery by finding where the rock had been struck, broken and moved by a rover wheel.

Murray Ridge is part of the western rim of Endeavour Crater, an impact scar that is billions of years old and about 14 miles (22 kilometers) in diameter.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Opportunity mission for NASA's Science Mission Directorate, Washington.

For more information about Opportunity, visit http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov
 
For more information about Mars Reconnaissance Orbiter (MRO), visit: http://mars.jpl.nasa.gov/mro/

Image, Text, Credit: NASA / JPL-Caltech / Univ. of Arizona.

Cheers, Orbiter.ch

RXTE Reveals the Cloudy Cores of Active Galaxies

NASA - Rossi X-ray Timing Explorer (RXTE) patch.

February 19, 2014

Picture a single cloud large enough to span the solar system from the sun to beyond Pluto's orbit. Now imagine many such clouds orbiting in a vast ring at the heart of a distant galaxy, occasionally dimming the X-ray light produced by the galaxy's monster black hole.

Using data from NASA's Rossi X-ray Timing Explorer (RXTE) satellite, an international team has uncovered a dozen instances where X-ray signals from active galaxies dimmed as a result of a cloud of gas moving across our line of sight. The new study triples the number of cloud events previously identified in the 16-year archive.

The Cloudy Cores of Active Galaxies

Video above: Zoom into the cloudy heart of an active galaxy. This animation shows an artist's rendition of the cloudy structure revealed by a study of data from NASA's Rossi X-Ray Timing Explorer satellite. Image Credit: NASA's Goddard Space Flight Center/Wolfgang Steffen, UNAM.

At the hearts of most big galaxies, including our own Milky Way, there lurks a supermassive black hole weighing millions to billions of times the sun's mass. As gas falls toward a black hole, it gathers into a so-called accretion disk and becomes compressed and heated, ultimately emitting X-rays. The centers of some galaxies produce unusually powerful emission that exceeds the sun's energy output by billions of times. These are active galactic nuclei, or AGN.

"One of the great unanswered questions about AGN is how gas thousands of light-years away funnels into the hot accretion disk that feeds the supermassive black hole," said Alex Markowitz, an astrophysicist at the University of California, San Diego and the Karl Remeis Observatory in Bamberg, Germany. "Understanding the size, shape and number of clouds far from the black hole will give us a better idea of how this transport mechanism operates."

Rossi X-ray Timing Explorer (RXTE) spacecraft

The study is the first statistical survey of the environments around supermassive black holes and is the longest-running AGN-monitoring study yet performed in X-rays. In the paper, which will appear in a future issue of Monthly Notices of the Royal Astronomical Society and is now published online, the scientists describe various properties of the occulting clouds, which vary in size and shape but average 4 billion miles (6.5 billion km) across – greater than Pluto's distance from the sun -- and twice the mass of Earth. They orbit a few light-weeks to a few light-years from the black hole.

RXTE's instruments measured variations in X-ray emission on timescales as short as microseconds and as long as years across a wide energy span, from 2,000 to 250,000 electron volts. For comparison, the energy of a typical dental X-ray is around 60,000 electron volts. NASA decommissioned the observatory in 2012, following 16 years of successful operation in Earth orbit.

"Because RXTE performed sustained observations of many of these AGN, our research is sensitive to a wide range of cloud events, from those as brief as five hours to as long as 16 years," said co-author Robert Nikutta, a theorist at Andrés Bello University in Santiago, Chile.

For decades, astronomers explained the different observed properties of AGN by suggesting that a relatively uniform "doughnut" of dust and gas surrounds the black hole and extends several light-years away from it. Interference from this material is lowest when we happen to be looking into the doughnut from above or below and greatest when we view it from the side. Now astronomers are moving toward a new generation of models that view the doughnut as a collection of many individual clouds mostly distributed along its central plane, a view supported by the RXTE study.

One of the more unusual events the team turned up occurred in NGC 3783, a barred spiral galaxy located 143 million light-years away toward the constellation Centaurus. "In 2008, the AGN dimmed twice over a period of 11 days and did not reach its typical X-ray brightness within that period," said co-author Mirko Krumpe of the European Southern Observatory in Garching, Germany. "This could be caused by an elongated, filamentary cloud, perhaps one that is in the process of being torn apart by the black hole."

Related Links:

Download HD video from NASA Goddard's Scientific Visualization Studio: http://svs.gsfc.nasa.gov/goto?11482

Paper: First X-ray-Based Statistical Tests for Clumpy-Torus Models: Eclipse Events from 230 Years of Monitoring of Seyfert AGN: http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stt2492

More about the Rossi X-Ray Timing Explorer: https://heasarc.gsfc.nasa.gov/docs/xte/XTE.html

"NASA's Rossi X-Ray Timing Explorer Completes Mission Operations" (01.09.12): http://orbiterchspacenews.blogspot.ch/2012/01/nasas-rossi-x-ray-timing-explorer.html

Active Galaxies and Quasars: Imagine the Universe!: http://imagine.gsfc.nasa.gov/docs/science/know_l2/active_galaxies.html

"X-ray 'Echoes' Map a Supermassive Black Hole's Environs" (05.31.12): http://www.nasa.gov/topics/universe/features/xray-echo.html

"Nearby Galaxy Boasts Two Monster Black Holes, Both Active" (06.10.11): http://orbiterchspacenews.blogspot.ch/2011/06/nearby-galaxy-boasts-two-monster-black.html

Science in the Media Curriculum: Black Holes and Active Galaxies: http://globalastro.gsfc.nasa.gov/?page_id=3548

Image, Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Francis Reddy.

Greetings, Orbiter.ch

NASA's NuSTAR Untangles Mystery of How Stars Explode

NASA - NuStar Mission patch.

February 19, 2014

 Sloshing Star Goes Supernova

Video above: NuSTAR is showing that exploding stars slosh around before blasting apart.This 3-D computer simulation demonstrates how the supernova explosion might look. Video Credit: NASA/JPL-Caltech.

One of the biggest mysteries in astronomy, how stars blow up in supernova explosions, finally is being unraveled with the help of NASA's Nuclear Spectroscopic Telescope Array (NuSTAR).

The high-energy X-ray observatory has created the first map of radioactive material in a supernova remnant. The results, from a remnant named Cassiopeia A (Cas A), reveal how shock waves likely rip massive dying stars apart.

Radioactive Core of a Dead Star

Image above: NASA's Nuclear Spectroscope Telescope Array, or NuSTAR, has, for the first time, imaged the radioactive "guts" of a supernova remnant, the leftover remains of a star that exploded. The NuSTAR data are blue, and show high-energy X-rays. Yellow shows non-radioactive material detected previously by NASA's Chandra X-ray Observatory in low-energy X-rays. Image credit: NASA/JPL-Caltech/CXC/SAO.

"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology (Caltech) in Pasadena. "Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."

Harrison is a co-author of a paper about the results appearing in the Feb. 20 issue of Nature.

The Case of Missing Iron in Cassiopeia A

Image above: When astronomers first looked at images of a supernova remnant called Cassiopeia A, captured by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, they were shocked. What they saw didn't match previous observations. The mystery of Cassiopeia A (Cas A), a massive star that exploded in a supernova more than 11,000 years ago, continues to confound researchers. Image credit: NASA/JPL-Caltech/CXC/SAO.

Cas A was created when a massive star blew up as a supernova leaving a dense stellar corpse and its ejected remains. The light from the explosion reached Earth a few hundred years ago, so we are seeing the stellar remnant when it was fresh and young.

Supernovas seed the universe with many elements, including the gold in jewelry, the calcium in bones and the iron in blood. While small stars like our sun die less violent deaths, stars at least eight times as massive as our sun blow up in supernova explosions. The high temperatures and particles created in the blast fuse light elements together to create heavier elements.

NuSTAR Data Point to Sloshing Supernovas

Images above: How massive stars blow up in powerful explosions called supernovas remains a mystery. Theorists have come up with computer simulations to try to recreate what happens, but it's not clear which model is correct. Now, new observations from NASA's Nuclear Spectroscopic Telescope Array of the heart of the Cassiopeia supernova remnant are allowing researchers to test those models with real evidence. Image credit: NASA/JPL-Caltech/CXC/SAO/SkyWorks Digital/Christian Ott.

NuSTAR is the first telescope capable of producing maps of radioactive elements in supernova remnants. In this case, the element is titanium-44, which has an unstable nucleus produced at the heart of the exploding star.

Image above: These illustrations show the progression of a supernova blast. A massive star (left), which has created elements as heavy as iron in its interior, blows up in a tremendous explosion (middle), scattering its outer layers in a structure called a supernova remnant (right). Image Credit: NASA/CXC/SAO/JPL-Caltech.

The NuSTAR map of Cas A shows the titanium concentrated in clumps at the remnant's center and points to a possible solution to the mystery of how the star met its demise. When researchers simulate supernova blasts with computers, as a massive star dies and collapses, the main shock wave often stalls out and the star fails to shatter.

The latest findings strongly suggest the exploding star literally sloshed around, re-energizing the stalled shock wave and allowing the star to finally blast off its outer layers.

Image above: Artist's concept of NuSTAR on orbit. NuSTAR has a 10-m (30') mast that deploys after launch to separate the optics modules (right) from the detectors in the focal plane (left). Image Credit: NASA/JPL-Caltech.

"With NuSTAR we have a new forensic tool to investigate the explosion," said the paper's lead author, Brian Grefenstette of Caltech. "Previously, it was hard to interpret what was going on in Cas A because the material that we could see only glows in X-rays when it's heated up. Now that we can see the radioactive material, which glows in X-rays no matter what, we are getting a more complete picture of what was going on at core of the explosion."

The NuSTAR map also casts doubt on other models of supernova explosions, in which the star is rapidly rotating just before it dies and launches narrow streams of gas that drive the stellar blast. Though imprints of jets have been seen before around Cas A, it was not known if they were triggering the explosion. NuSTAR did not see the titanium, essentially the radioactive ash from the explosion, in narrow regions matching the jets, so the jets were not the explosive trigger.

Untangling the Remains of Cassiopeia A

Image above: The mystery of how Cassiopeia A exploded is unraveling thanks to new data from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR. In this image, NuSTAR data, which show high-energy X-rays from radioactive material, are colored blue. Lower-energy X-rays from non-radioactive material, imaged previously with NASA's Chandra X-ray Observatory, are shown in red, yellow and green. Image credit: NASA/JPL-Caltech/CXC/SAO.

"This is why we built NuSTAR," said Paul Hertz, director of NASA's astrophysics division in Washington. "To discover things we never knew – and did not expect – about the high-energy universe."

The researchers will continue to investigate the case of Cas A's dramatic explosion. Centuries after its death marked our skies, this supernova remnant continues to perplex.

For more information about NuSTAR and images, visit: http://www.nasa.gov/nustar

Images (mentioned), Text, Credits: NASA / J.D. Harrington / JPL / Whitney Clavin.

Best regards, Orbiter.ch

Martian Dunes Flying in Formation

NASA - Mars Reconnaissance Orbiter (MRO) logo.

Feb. 19, 2014

Dunes Flying in Formation

Migratory birds and military aircraft often fly in a V-shaped formation. The “V” formation greatly boosts the efficiency and range of flying birds, because all except the first fly in the upward motion of air -- called upwash -- from the wingtip vortices of the bird ahead.

In this image of a dune field on Mars in a large crater near Mawrth Vallis, some of the dunes appear to be in a V-shaped formation. For dune fields, the spacing of individual dunes is a function of sand supply, wind speed, and topography.

 Martian Dunes Flying in Formation

This image was acquired by the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter on Dec. 30, 2013. The University of Arizona, Tucson, operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for the NASA Science Mission Directorate, Washington.

For more information about Mars Reconnaissance Orbiter (MRO), visit: http://mars.jpl.nasa.gov/mro/

More information and image products: http://www.uahirise.org/ESP_034815_2035

Image, Video, Text, Credits:  Credit: NASA / JPL-Caltech/ Univ. of Arizona / Caption: Alfred McEwen.

Greetings, Orbiter.ch

Hubble Watches Stars' Clockwork Motion In Nearby Galaxy

NASA - Hubble Space Telescope patch.

February 19, 2014

Image above: This artist’s illustration shows Hubble measurements of the rotation of the Large Magellanic Cloud (LMC), the nearest normal-sized galaxy to our Milky Way. The LMC appears in the southern-hemisphere night sky, as seen in this ground-based image. Image Credit: NASA/ESA.

Using the sharp-eyed NASA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.

According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years. It takes our sun the same amount of time to complete a rotation around the center of our Milky Way galaxy.

The Hubble team -- Roeland van der Marel of the Space Telescope Science Institute in Baltimore, Md., and Nitya Kallivayalil of the University of Virginia in Charlottesville, Va. -- used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away. Hubble recorded the stars' slight movements during a seven-year period.

"Studying this nearby galaxy by tracking the stars' movements gives us a better understanding of the internal structure of disk galaxies," said Kallivayalil, "Knowing a galaxy's rotation rate offers insight into how a galaxy formed, and it can be used to calculate its mass."

Disk-shaped galaxies such as the Milky Way and the LMC generally rotate like a carousel. Hubble's precision tracking offers a new way to determine a galaxy's rotation by the "sideways" proper motion of its stars, as seen in the plane of the sky. Astronomers have long measured the sideways motions of nearby celestial objects, but this is the first time the precision has become sufficient to see another distant galaxy rotate.

"The LMC is a very important galaxy because it is very near to our Milky Way," said van der Marel, who is the lead author on a paper in the Feb. 1 issue of the Astrophysical Journal. "Studying the Milky Way is difficult because you're studying from the inside, so everything you see is spread all over the sky. It's all at different distances, and you're sitting in the middle of it. Studying structure and rotation is much easier if you view a nearby galaxy from the outside."

For the past century, astronomers have calculated galaxy rotation rates by observing a slight shift in the spectrum of its starlight. This shift is known as the Doppler Effect. On one side of a galaxy's spinning stellar disk, the stars swinging in the direction of Earth will show a spectral blueshift -- the compression of light waves due to motion toward the observer. Stars swinging away from Earth on the opposite side of a galaxy will show a spectral redshift -- the stretching of light to redder wavelengths due to motion away from the observer.

The newly measured Hubble motions and the Doppler motions measured previously provide complementary information about the LMC's rotation rate. By combining the results, the Hubble team obtained a fully three-dimensional view of stellar motions in another galaxy.

"By using Hubble to study the stars' motions over several years, we can actually, for the first time, see a galaxy rotate in the plane of the sky," said van der Marel.

Hubble is the only telescope that can make this kind of observation because of its sharp resolution, its image stability, and its 24 years in space.

Hubble Space Telescope. Image Credits: NASA / ESA.

"If we imagine a human on the moon, Hubble's precision would allow us to determine the speed at which the person's hair grows," van der Marel explained. "This precision is crucial, because the apparent stellar motions are so small because of the galaxy's distance. You can think of the LMC as a clock in the sky, on which the hands take 250 million years to make one revolution. We know the clock's hands move, but even with Hubble we need to stare at them for several years to see any movement."

The research team used Hubble's Wide Field Camera 3 and Advanced Camera for Surveys to observe stars in 22 fields spread across the vast disk of the LMC, which appears in the southern night sky as an object about 20 times the diameter of the moon. Arrows on the accompanying image show the predicted motion over the next 7 million years, based on the Hubble measurements.

Each observed field contains not only dozens of LMC stars, but also a background quasar, a brilliant beacon of light powered by a black hole in the core of the distant active galaxy. The astronomers used the quasars as fixed reference points to measure the subtle motion of the LMC stars.

This measurement is the culmination of ongoing work with Hubble to refine the calculation of the LMC's rotation rate. Van der Marel began analyzing the galaxy's rotation in 2002 by creating detailed predictions, now confirmed by Hubble, of what the rotation should look like.

"Because the LMC is nearby, it is a benchmark for studies of stellar evolution and populations," Kallivayalil said. "For this, it's important to understand the galaxy's structure. Our technique for measuring the galaxy's rotation rate using fully three-dimensional motions is a new way to shed light on that structure. It opens a new window to our understanding of how stars in galaxies move."

The team next plans to use Hubble to measure the stellar motions in the LMC's diminutive cousin, the Small Magellanic Cloud, using the same technique. The galaxies are interacting, and that study should also yield improved insight into how the galaxies are moving around each other and around the Milky Way.

Notes:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

For a graphic and video illustration of these results, visit: http://hubblesite.org/news/2014/11

For more information about NASA's & ESA's Hubble Space Telescope, visit: http://www.nasa.gov/hubble and http://www.spacetelescope.org/

Images (mentioned), Text, Credits: NASA / J.D. Harrington / Space Telescope Science Institute / Donna Weaver / Ray Villard.

Cheers, Orbiter.ch

Diamonds in the Tail of the Scorpion

ESO - European Southern Observatory logo.

19 February 2014

New ESO image of star cluster Messier 7

The star cluster Messier 7

A new image from ESO’s La Silla Observatory in Chile shows the bright star cluster Messier 7. Easily spotted with the naked eye close to the tail of the constellation of Scorpius, it is one of the most prominent open clusters of stars in the sky — making it an important astronomical research target.

Messier 7, also known as NGC 6475, is a brilliant cluster of about 100 stars located some 800 light-years from Earth. In this new picture from the Wide Field Imager on the MPG/ESO 2.2-metre telescope it stands out against a very rich background of hundreds of thousands of fainter stars, in the direction of the centre of the Milky Way.

The bright star cluster Messier 7 in the constellation of Scorpius

At about 200 million years old, Messier 7 is a typical middle-aged open cluster, spanning a region of space about 25 light-years across. As they age, the brightest stars in the picture — a population of up to a tenth of the total stars in the cluster — will violently explode as supernovae. Looking further into the future, the remaining faint stars, which are much more numerous, will slowly drift apart until they become no longer recognisable as a cluster.

Open star clusters like Messier 7 are groups of stars born at almost the same time and place, from large cosmic clouds of gas and dust in their host galaxy. These groups of stars are of great interest to scientists, because the stars in them have about the same age and chemical composition. This makes them invaluable for studying stellar structure and evolution.

Zooming in on the bright star cluster Messier 7

An interesting feature in this image is that, although densely populated with stars, the background is not uniform and is noticeably streaked with dust. This is most likely to be just a chance alignment of the cluster and the dust clouds. Although it is tempting to speculate that these dark shreds are the remnants of the cloud from which the cluster formed, the Milky Way will have made nearly one full rotation during the life of this star cluster, with a lot of reorganisation of the stars and dust as a result. So the dust and gas from which Messier 7 formed, and the star cluster itself, will have gone their separate ways long ago.

Panning across the bright star cluster Messier 7

The first to mention this star cluster was the mathematician and astronomer Claudius Ptolemy, as early as 130 AD, who described it as a “nebula following the sting of Scorpius”, an accurate description given that, to the naked eye, it appears as a diffuse luminous patch against the bright background of the Milky Way. In his honour, Messier 7 is sometimes called Ptolemy’s Cluster. In 1764 Charles Messier included it as the seventh entry in his Messier catalogue. Later, in the 19th century, John Herschel described the appearance of this object as seen through a telescope as a “coarsely scattered cluster of stars” — which sums it up perfectly.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

Photos of the MPG/ESO 2.2-metre telescope: http://www.eso.org/public/images/archive/search/?adv=&subject_name=mpg

Photos from the MPG/ESO 2.2-metre telescope: http://www.eso.org/public/images/archive/search/?adv=&facility=15

Photos of La Silla: http://www.eso.org/public/images/archive/category/lasilla/

Images, Text, Credits: ESO / IAU and Sky & Telescope / Videos: ESO / Nick Risinger (skysurvey.org) Music: movetwo.

Greetings, Orbiter.ch

Cassini Images Terrain of Saturn's Moon Dione

NASA / ESA - Cassini International logo.

Feb. 18, 2014

The Wisps of Dione

Although the crack-like features seen here on Dione’s surface appear wispy and faded, they are in reality a series of geologically fresh fractures!

See PIA10560 to learn more about Dione's wispy terrain: http://photojournal.jpl.nasa.gov/catalog/PIA10560

Lit terrain seen here is on the trailing hemisphere of Dione. North on Dione (698 miles, or 1,123 kilometers across) is up and rotated 29 degrees to the left.  The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 10, 2013.

The view was acquired at a distance of approximately 554,000 miles (892,000 kilometers) from Dione. Image scale is three miles (five kilometers) per pixel.

At Carthage Linea

Image above: Dione's icy surface is scarred by craters and sliced up by multiple generations of geologically-young bright fractures. Numerous fine, roughly-parallel linear grooves run across the terrain in the upper left corner. Image Credit: NASA/JPL/Space Science Institute.

Most of the craters seen here have bright walls and dark deposits of material on their floors. As on other Saturnian moons, rockslides on Dione (1,126 kilometers, or 700 miles across) may reveal cleaner ice, while the darker materials accumulate in areas of lower topography and lower slope (e.g. crater floors and the bases of scarps).

The terrain seen here is centered at 15.4 degrees north latitude, 330.3 degrees west longitude, in a region called Carthage Linea. North on Dione is up and rotated 50 degrees to the left.

The image was taken in visible green light with the Cassini narrow-angle camera on Oct. 11, 2005, at a distance of approximately 19,600 kilometers (12,200 miles) from Dione. The image scale is about 230 meters (760 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 and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image (mentioned), Text, Credits: Credit: NASA / JPL-Caltech / Space Science Institute.

Best regards, Orbiter.ch