Ever imagine creating your own IMAX movie? Cinematographer Stephen Van Vuuren is working to do just that, and has created flythough sequences from thousands of images from the Cassini spacecraft’s tour of the Saturn system. The video above is just a sampling of this non-profit, giant-screen art film effort “that takes audiences on a journey of the mind, heart and spirit from the big bang to the near future via the Cassini-Huygens Mission at Saturn,” according to the “Outside In” website.
Saturn, its rings and moons small to large in this Cassini image. Credit: NASA/JPL/Space Science Institute
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This latest offering from the Cassini spacecraft shows a wide-angle view of Saturn, its rings, and a sampling of the planet’s moons in varying sizes. Saturn’s largest moon, Titan, is in the center of the image, with the smaller moon Enceladus on the far right, while appearing just below the rings on the far left beyond the thin F ring is teeny-tiny Pandora. Oh, to have this view out your spacecraft window as you approach the ringed-world for a flyby!
How do the moons shown here vary in size? Titan is 5,150 kilometers, or 3,200 miles, across. Enceladus is 504 kilometers, or 313 miles across, while Pandora is 81 kilometers, or 50 miles across. This view looks toward anti-Saturn side of Titan and toward the northern, sunlit side of the rings from just above the ringplane.
The image was taken with the Cassini spacecraft wide-angle camera on Jan. 15, 2011, from a distance of about 844,000 kilometers (524,000 miles) from Titan. Image scale is 50 kilometers (31 miles) per pixel.
Titan peeks from behind two of Saturn's rings. Another small moon Epimetheus, appears just above the rings. Credit: NASA/JPL/Space Science Institute
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It seems Titan is getting more Earth-like all the time. There are lakes, rainfall (never mind that any liquids on Titan are frigid hydrocarbons), dust storms, lightning and all sorts of other activity going on it the atmosphere, along with clouds. And now, not just any clouds but cirrus clouds, very similar to what we have on Earth: thin, wispy clouds of ice particles high in the atmosphere. A team of researchers at NASA’s Goddard Space Flight Center say that unlike Titan’s brownish haze, the ice clouds are pearly white.
“This is the first time we have been able to get details about these clouds,” said Robert Samuelson, an emeritus scientist at Goddard and the co-author of a new paper published in the journal Icarus. “Previously, we had a lot of information about the gases in Titan’s atmosphere but not much about the [high-altitude] clouds.”
Using the Composite Infrared Spectrometer (CIRS) on NASA’s Cassini spacecraft scientists can get a “weather report” of sorts. Previously, scientists have found that Titan’s intriguing atmosphere has a one-way cycle that delivers hydrocarbons and other organic compounds to the ground as precipitation.
Those compounds don’t evaporate to replenish the atmosphere, but somehow the supply has not run out.
Additionally, puffy methane and ethane clouds had been found before by ground-based observers and in images taken by Cassini. But these new clouds are much thinner and located higher in the atmosphere.
“They are very tenuous and very easy to miss,” said Carrie Anderson, the paper’s lead author. “The only earlier hints that they existed were faint glimpses that NASA’s Voyager 1 spacecraft caught as it flew by Titan in 1980.”
So what are these cirrus clouds made of?
This mosaic of Titan was created from the first flyby of the moon by Cassini in 2004. Credit: NASA/JPL/SS
More than a half-dozen hydrocarbons have been identified in gas form in Titan’s atmosphere, but many scientists feel there are probably many more that haven’t yet been identified.
The clouds on Titan can’t be made from water because of the planet’s extreme cold. “If Titan has any water on the surface, it would be solid as a rock,” said Goddard’s Michael Flasar, the Principal Investigator for CIRS.
Instead, the key ingredient is likely methane. High in the atmosphere, some of the methane breaks up and reforms into ethane and other hydrocarbons, or combines with nitrogen to make materials called nitriles. Any of these compounds can probably form clouds if enough accumulates in a sufficiently cold area.
To find these cloud, the team focuses on the observations made when CIRS is positioned to peer into the atmosphere at an angle, grazing the edge of Titan. This path through the atmosphere is longer than the one when the spacecraft looks straight down at the surface. Planetary scientists call this “viewing on the limb,” and it raises the odds of encountering enough molecules of interest to yield a strong signal.
So, when the researchers look at the data, they can separate the telltale signatures of ice clouds from the other aerosols in the atmosphere. “These beautiful, beautiful ice clouds are optically thin, and they’re diffuse,” said Anderson. “But we were able to pick up on them because of the long path lengths of the observations.”
Saturn's moon Helene. Credit: NASA//JPL/SSI, image enhanced by Stu Atkinson
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The Cassini spacecraft recently had a mini ‘grand tour’ of several of Saturn’s moons and just sent back some great images of Helene, Mimas, Enceladus and Dione. Above is an amazing view of the Trojan moon Helene, which is only 32 kilometers (20 miles across) and shares an orbit with Dione. Cassini came withing 28,000 km (17,398 miles) of Helene. Thanks to Stu Atkinson for an enhanced version of this raw Cassini image. See one of the original raw images of Helene here.
This image of Saturn's moon Enceladus was obtained by NASA's Cassini spacecraft on Jan. 31, 2011. It shows the famous jets erupting from the south polar terrain of Enceladus. Image credit: NASA/JPL/SSI
Cassini captured several images of the plumes spewing from Enceladus, and other closeup views of the moon’s terrain.
Closeup of Enceladus from approximately 78,015 kilometers away. Credit: NASA/JPL/SSIThis view shows the bright, icy Mimas in front of Saturn's delicate rings. Image credit: NASA/JPL/SSI
A close look at Enceladus, with Saturn's rings in the background. Credit: NASA/JPL/Space Science Institute
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The Cassini spacecraft has taken a some recent images of two of Saturn’s most notorious moons, where in both images the planet’s rings serve as a backdrop. Above, Enceladus stands out with its cratered surface, but Cassini’s camera also catches a glimpse of the planet’s rings in the background. Geologically young terrain in the middle latitudes of the moon shifts to older, cratered terrain in the northern latitudes.
The image was taken during the spacecraft’s flyby of Enceladus on Nov. 30, 2010, in visible with Cassini’s spacecraft narrow-angle camera, from a distance of approximately 46,000 kilometers (29,000 miles) from Enceladus. Image scale is 276 meters (906 feet) per pixel.
Below is a ‘raw’ view of Titan, and the rings.
A closeup of Titan rings, in front of Saturn's rings. Credit: NASA/JPL/Space Science Institute.
This close-up view of Titan was taken on January 15, 2011, shows the cloudy atmosphere of the moon, with the rings in the background. Cassini was about 839,213 kilometers away from Titan.
Enceladus and Dione, as seen by Cassini. Credit: NASA/JPL/Space Science Institute
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We’ve all experienced the Moon Illusion, where our own full Moon looks bigger when seen on the Earth’s horizon. But how about this illusion where you can’t really tell which of these two moons of Saturn is actually bigger, or which is closer, as seen by the Cassini spacecraft? Here, Dione, top right, appears closer to the spacecraft because it is larger than the moon Enceladus, lower left. However, Enceladus was actually closer to Cassini when its visible light, narrow-angle camera took this image.
Dione (1,123 kilometers, or 698 miles, across) is more than twice the size of Enceladus (504 kilometers, or 313 miles, across). The two moons are contrasted with Enceladus’ bright, reflective trailing hemisphere, and Dione’s darker, micrometeor-dusted side, decorated with wispy lighter materials.
Cassini took this image on Dec. 1, 2010 from about 510,000 kilometers (317,000 miles) from Enceladus and approximately 830,000 kilometers (516,000 miles) from Dione. Image scale is 3 kilometers (2 miles) per pixel on Enceladus and 5 kilometers (3 miles) per pixel on Dione.
Rhea, Saturn's rings and some sister moons. Credit: NASA/JPL/Space Science Institute
Jia-Rui C. Cook from the Cassini team sent out an alert that raw images from Cassini’s closest flyby of Saturn’s moon Rhea have begun streaming to Cassini’s raw image page, and they are well worth a look. At closest approach, Cassini came within about 69 kilometers (43 miles) of Rhea’s surface on Jan. 11. But there’s also some interesting group photos from within the Saturn System. One of the best is this image, above. How many moons can you find? I probably wouldn’t have seen them all but Emily Lakdawalla at the Planetary Blog spied five moons and the rings in this one wide-angle shot. The large moon is Rhea; above Rhea and just below the rings, is Dione; above and to the left of Rhea is Tethys. Then there are two tiny moons: squint hard to see Prometheus as tiny lump on the rings to the left of Dione, and Epimetheus is hovering between Tethys and Rhea. See some more, including closeups of Rhea and Saturn’s storm, below.
Hemispheric color differences on Saturn's moon Rhea are apparent in this false-color view from NASA's Cassini spacecraft. This image shows the side of the moon that always faces the planet. Image Credit: NASA/JPL/SSI
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Saturn’s second largest moon Rhea has gotten a couple of close-up looks by the Cassini spacecraft which show dramatic views of fractures cutting through craters on the moon’s surface. The new images reveal a history of tectonic rumbling, scientists say. The images are among the highest-resolution views ever obtained of Rhea, including a 3-D look at a tectonically fractured region showing cracks as deep as 4 kilometers (2.5 miles).
“These recent, high-resolution Cassini images help us put Saturn’s moon in the context of the moons’ geological family tree,” said Paul Helfenstein, Cassini imaging team associate, based at Cornell University, Ithaca, N.Y. “Since NASA’s Voyager mission visited Saturn, scientists have thought of Rhea and Dione as close cousins, with some differences in size and density. The new images show us they’re more like fraternal twins, where the resemblance is more than skin deep. This probably comes from their nearness to each other in orbit.”
Cassini made to two close passes of Rhea on Nov. 21, 2009 and March 2, 2010, and the flybys were designed in part to search for a ring thought to encircle the moon, the existence of which has now been ruled out. During the March flyby, Cassini made its closest- approach to Rhea’s surface so far, swooping within 100 kilometers (62 miles) of the moon.
Icy fractures on Saturn's moon Rhea reflect sunlight brightly in this high-resolution mosaic created from images captured by NASA's Cassini spacecraft during its March 2, 2010, flyby. This flyby was the closest flyby of Rhea up to then. Image Credit: NASA/JPL/SSI
These unique views are among the best ever obtained of the side of Rhea that always faces away from Saturn. Other views show a web of bright, “wispy” fractures resembling some that were first spotted on another part of Rhea by the two Voyager spacecraft in 1980 and 1981. These images are helping to answer questions scientists have had about Rhea since the Voyager mission.
At that time, scientists thought the wispy markings on the trailing hemispheres – the sides of moons that face backward in the orbit around a planet – of Rhea and the neighboring moon Dione were possible cryovolcanic deposits, or the residue of icy material erupting. The low resolution of Voyager images prevented a closer inspection of these regions. Since July 2004, Cassini’s imaging cameras have captured pictures the trailing hemispheres of both satellites several times at much higher resolution. The images have shown that the wispy markings are actually exposures of bright ice along the steep walls of long scarps, or lines of cliffs, which indicate tectonic activity produced the features rather than cryovolcanism.
Wispy fractures cut through cratered terrain on Saturn's moon Rhea in this high resolution, 3-D image from NASA's Cassini spacecraft. The image shows a level of detail not seen previously. Image Credit: NASA/JPL/SSI
Scientists combined images of the trailing hemisphere taken about one hour apart to create a 3-D image revealing a set of closely spaced troughs that sometimes look linear and sometimes look sinuous. The 3-D image also shows uplifted blocks interspersed through the terrain that cut through older, densely cratered plains. While the densely cratered plains imply that Rhea has not experienced much internal activity since its early history that would have repaved the moon, these imaging data suggest that some regions have ruptured in response to tectonic stress more recently. Troughs and other fault topography cut through the two largest craters in the scene, which are not as scarred with smaller craters, indicating that these craters are comparatively young. In some places, material has moved downslope along the scarps and accumulated on the flatter floors.
A mosaic of the March flyby images shows bright, icy fractures cutting across the surface of the moon, sometimes at right angles to each other. A false-color view of the entire disk of the moon’s Saturn-facing side reveals a slightly bluer area, likely related to different surface compositions or to different sizes and fine-scale textures of the grains making up the moon’s icy soil.
This global digital map of Saturn's moon Rhea was created using data obtained by NASA's Cassini and Voyager spacecraft. Image Credit: NASA/JPL/SSI
The new images have also helped to enhance maps of Rhea, including the first cartographic atlas of features on the moon complete with names approved by the International Astronomical Union. Cassini will continue to chart the terrain of this and other Saturnian moons with ever-improving resolution, especially for terrain at high northern latitudes, until 2017.
An upcoming flyby should provide even more details about Rhea.
“The 11th of January 2011 will be especially exciting, when Cassini flies just 76 kilometers [47 miles] above the surface of Rhea,” said Thomas Roatsch, a Cassini imaging team scientist based at the German Aerospace Center Institute of Planetary Research in Berlin. “These will be by far the best images we’ve ever had of Rhea’s surface – details down to just a few meters will become recognizable.”
Titan and Tethys line up for a portrait of 'sibling' moons. Credit: NASA/JPL/Space Science Institute
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This image reminds me of when I was young, my parents would line me and my siblings up for pictures, oldest and tallest in the back and youngest and smallest in the front. Here, the Cassini spacecraft sees two of Saturn’s moons lined up for a family photo, showing the hazy orb of giant Titan beyond smaller Tethys.
On Tethys, the large Ithaca Chasma can be seen running roughly north-south for more than 1,000 kilometers (620 miles). Titan’s hazy atmosphere covers up the interesting surface below.
This view looks toward the Saturn-facing sides of Titan (5,150 kilometers, or 3,200 miles across) and Tethys (1,062 kilometers, or 660 miles across).
