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The Official *Saturn* Exploration Thread


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The Official *Saturn* Exploration Thread
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curiousuburb
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Join Date: May 2004
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2010-02-23, 20:40

How about Moby Dick (bonus anaglyph 3D version)



Quote:
Behold the Violent History of Saturn’s White Whale Moon


Like the battered white whale Moby Dick taunting Captain Ahab, Saturn’s moon Prometheus surges toward the viewer in a 3-D image from NASA’s Cassini spacecraft.

The image exposes the irregular shape and circular surface scars on Prometheus, pointing to a violent history. These craters are probably the remnants from impacts long ago.

Prometheus is one of Saturn's innermost moons. It orbits the gas-giant at a distance of about 140,000 kilometers (86,000 miles) and is 86 kilometers (53 miles) across at its widest point. The porous, icy world was originally discovered in images taken by NASA’s Voyager 1 spacecraft back in 1980.

Cassini’s narrow-angle camera captured two black-and-white images of the moon on Dec. 26, 2009, and the imaging team combined the images to make this new stereo view. It looks different from the 'egg-cellent' raw image of Prometheus obtained on Jan. 27 because that view shows one of the short ends of the oddly shaped moon. In this 3-D image, the sun illuminates Prometheus at a different angle, making the moon’s elongated body visible.
Meanwhile... on Enceladus...

Quote:

Bursting at the Seams

February 23, 2010 Full-Res: PIA11688

Dramatic plumes, both large and small, spray water ice out from many locations along the famed "tiger stripes" near the south pole of Saturn's moon Enceladus. The tiger stripes are fissures that spray icy particles, water vapor and organic compounds.

More than 30 individual jets of different sizes can be seen in this image and more than 20 of them had not been identified before. At least one jet spouting prominently in previous images now appears less powerful.

This mosaic was created from two high-resolution images that were captured by the narrow-angle camera when NASA’s Cassini spacecraft flew past Enceladus and through the jets on Nov. 21, 2009. (For other images captured during the same flyby, see Enceladan Tectonics and Baghdad Sulcus in 3-D ). Imaging the jets over time will allow Cassini scientists to study the consistency of their activity.

The south pole of the moon lies near the limb in the top left quadrant of the mosaic, near the large jet that is second from left. Lit terrain seen here is on the leading hemisphere of Enceladus (504 kilometers, 313 miles across).

Cassini scientists continue to study the question of whether reservoirs of liquid water exist beneath the surface of the moon. See Baghdad and Cairo Sulci on Enceladus and Jet Blue to learn more.

The view was obtained at a distance of approximately 14,000 kilometers (9,000 miles) from Enceladus and at a sun-Enceladus-spacecraft, or phase, angle of 145 degrees. Image scale is 81 meters (267 feet) per pixel.

...



Enceladus' Warm Baghdad Sulcus

February 23, 2010 Full-Res: PIA11696

In this unique mosaic image combining high-resolution data from the imaging science subsystem and composite infrared spectrometer aboard NASA’s Cassini spacecraft, pockets of heat appear along one of the mysterious fractures in the south polar region of Saturn’s moon Enceladus. The fracture, named Baghdad Sulcus, is one of the so-called “tiger stripe” features that erupt with jets of water vapor and ice particles. It runs diagonally across the image.

This mosaic, obtained on Nov. 21, 2009, shows a 40-kilometer (25-mile) segment of Baghdad Sulcus and illustrates the correlation between the geologically youthful surface fractures and anomalously warm temperatures recorded in the south polar region. It shows the highest-resolution data yet of the heat leaking from the moon’s interior along the tiger stripes.

The image shows that broad swaths of heat previously detected by the infrared spectrometer are confined to a narrow, intense region no more than a kilometer (half a mile) wide along the fracture. The thermal image also reveals that the strength of the thermal radiation varies considerably along the length of this fissure segment. The temperature along Baghdad Sulcus reached more than 180 Kelvin (about minus 140 degrees Fahrenheit).

This mosaic layers temperature data atop of a visible-light image and alignment of the two data sets is approximate. The mosaic is centered near 80 degrees south latitude and 30 degrees west longitude. The V-shaped valleys that distinguish Baghdad are about 500 meters (1,600 feet) deep. The 30-degree slopes that rise along the valleys appear to be coated with smooth-looking particulate deposits that are peppered with large ice blocks that can reach tens of meters (yards) in size. The smooth materials most likely represent ice grain fallout from active jets that erupt along this warm and active section of Baghdad. The ice blocks appear to be icy rubble that may have been exposed by scouring from the eruptions, seismic shaking, and down-slope settling of the finer ice particles.

The moon's south pole lies outside of the frame of the mosaic, in the darkness below what is shown here. The full-length of Baghdad Sulcus, one of the longest tiger stripes, stretches about 175 kilometers (109 miles) all the way across the south polar region. This high-resolution view focuses only on one end of the rift, in the hemisphere that always faces toward Saturn. The other end of Baghdad was in shadow when these images were obtained. See Enceladus Polar Maps - South Pole - October 2009 to see all of Baghdad Sulcus and the other tiger stripes.

... continues ...
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curiousuburb
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2010-03-29, 18:22

Mimas isn't the Death Star... it's Pac-Man

Quote:
Originally Posted by NASA

Goddard Instrument Aboard Cassini Spacecraft Sees 'Pac-Man' on Saturn Moon
03.29.10


The highest-resolution-yet temperature map and images of Saturn’s icy moon Mimas obtained by NASA’s Cassini spacecraft reveal surprising patterns on the surface of the small moon, including unexpected hot regions that resemble “Pac-Man” eating a dot, and striking bands of light and dark in crater walls.

The left portion of this image shows Mimas in visible light, an image that has drawn comparisons to the "Star Wars" Death Star. The right portion shows the new temperature map, which resembles 1980s video game icon "Pac Man." Credit: NASA/JPL/Goddard/SWRI/SSI
› Click for Larger image
“Other moons usually grab the spotlight, but it turns out Mimas is more bizarre than we thought it was,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “It has certainly given us some new puzzles.”

Cassini collected the data on Feb. 13, during its closest flyby of the moon, which is marked by an enormous scar called Herschel Crater and resembles the Death Star from “Star Wars.”

This figure illustrates the unexpected and bizarre pattern of daytime temperatures found on Saturn's small inner moon Mimas (396 kilometers, or 246 miles, in diameter). The data were obtained by the composite infrared spectrometer (CIRS) on NASA’s Cassini spacecraft during the spacecraft's closest-ever look at Mimas on Feb. 13, 2010. Credit: NASA/JPL/Goddard/SWRI/SSI
› Click for Larger image
Scientists working with the composite infrared spectrometer, which mapped Mimas’ temperatures, expected smoothly varying temperatures peaking in the early afternoon near the equator. Instead, the warmest region was in the morning, along one edge of the moon’s disk, making a sharply defined Pac-Man shape, with temperatures around 92 Kelvin (minus 294 degrees Fahrenheit). The rest of the moon was much colder, around 77 Kelvin (minus 320 degrees Fahrenheit). A smaller warm spot -- the dot in Pac-Man’s mouth -- showed up around Herschel, with a temperature around 84 Kelvin (minus 310 degrees Fahrenheit).

“Even though we can’t explain the observed pattern of surface temperatures on Mimas, the giant Herschel crater is a leading suspect,” said Dr. Mike Flasar, composite infrared spectrometer principal investigator from NASA Goddard Space Flight Center in Greenbelt, Md. “The energy of impact that created it several billion years ago has been estimated to be one-seventh of Mimas’s own gravitational energy. Anything much larger would likely have torn the moon apart. We really would like to see if there is also an anomalous temperature pattern on the other side of Herschel, which has not been observed so closely.”

The warm spot around Herschel makes sense because tall crater walls (about 5 kilometers, or 3 miles, high) can trap heat inside the crater. But scientists were completely baffled by the Pac-Man shape.

“We suspect the temperatures are revealing differences in texture on the surface,” said John Spencer, a composite infrared spectrometer team member based at Southwest Research Institute in Boulder, Colo. “It’s maybe something like the difference between old, dense snow and freshly fallen powder.”

Denser ice quickly conducts the heat of the sun away from the surface, keeping it cold during the day. Powdery ice is more insulating and traps the sun’s heat at the surface, so the surface warms up.

Even if surface texture variations are to blame, scientists are still trying to figure out why there are such sharp boundaries between the regions, Spencer said. It is possible that the impact that created Herschel Crater melted surface ice and spread water across the moon. That liquid may have flash-frozen into a hard surface. But it is hard to understand why this dense top layer would remain intact when meteorites and other space debris should have pulverized it by now, Spencer said.

Icy spray from the E ring, one of Saturn’s outer rings, should also keep Mimas relatively light-colored, but the new visible-light images from the flyby paint a picture of surprising contrasts. Cassini imaging team scientists didn’t expect to see dark streaks trailing down the bright crater walls or a continuous, narrow pile of concentrated dark debris tracing the foot of each wall.

The pattern may appear because of the way the surface of Mimas ages, said Paul Helfenstein, a Cassini imaging team associate based at Cornell University, Ithaca, N.Y. Over time, the moon’s surface appears to accumulate a thin veil of silicate minerals or carbon-rich particles, possibly because of meteor dust falling onto the moon or impurities already embedded in surface ice.

As the sun’s warming rays and the vacuum of space evaporate the brighter ice, the darker material is concentrated and left behind. Gravity pulls the dark material down the crater walls, exposing fresh ice underneath. Although similar effects are seen on other moons of Saturn, the visibility of these contrasts on a moon continually re-paved with small particles from the E ring helps scientists estimate rates of change on other satellites.

“These processes are not unique to Mimas, but the new high-definition images are like Rosetta stones for interpreting them,” Helfenstein said.

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 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. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md., where the instrument was built.
Waka-waka-waka
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curiousuburb
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2010-11-03, 10:20

Saturn's rings model galaxy formation

Click images for sources.
Quote:

Oscillations at B Ring edge

Saturn’s largest ring appears to behave like a mini spiral galaxy. NASA’s Cassini spacecraft caught enormous waves sloshing back and forth across Saturn’s B ring, similar to waves believed to give galaxies their spiral shapes.


This movie, made from images obtained by NASA's Cassini spacecraft of the outer edge of Saturn's B ring, reveals the combined effects of a tugging moon and oscillations that can naturally occur in disks like Saturn's rings and spiral galaxies.

The B ring is shown at the lower left of the frame, and its outer edge varies with time, moving in and out in this concatenation of 92 images, each taken about 6 minutes apart, over the span of 9 hours, 30 minutes. The Cassini Division, the division between the A and B rings once thought to be empty, dominates the upper right of the frame. The Huygens Ringlet runs across the middle of the frame from the upper left to lower right.

At its innermost radial distance, the B ring's edge is 117,470 kilometers (72,992 miles) from the center of Saturn. At its outermost radial distance, the B ring's edge is 117,670 kilometers (73,117 miles) from the center of Saturn. These variations amount to a difference of 200 kilometers (about 120 miles).

Cassini scientists have determined that the complicated radial variations in the B ring edge are caused by the presence of four scalloped patterns, all independently rotating around the ring. One pattern, with two lobes, is present because of the gravitational perturbations from the moon Mimas, which alter the ring particle orbits because of a repetitive configuration of particle and satellite orbital positions known as a Lindblad resonance; this pattern always stays fixed with respect to Mimas. The other patterns with one, two, and three lobes respectively, travel around the ring with differing speeds and are believed to be natural modes of oscillation of the ring in this vicinity, excited by a process known as "viscous overstability."

In this process, the small, random motions of the ring particles feed energy into a wave that propagates outward across the ring from an inner boundary, reflects off the outer edge of the B ring (which becomes distorted as a result), and then travels inward until it reflects off the inner boundary. This continuous back-and-forth reflection is necessary for these wave patterns to grow and become visible as distortions in the outer edge of the B ring.

In supporting these so-called "self-excited" modes, the outer edge of the B ring is behaving the way astronomers believe spiral galaxies behave. However, such modes are not directly observable in galaxies. Cassini's observations of the outer B ring edge constitute the first time such large-scale modes in a broad disk of material have been observed in nature.

“This is a major result,” said Cassini imaging team leader Carolyn Porco of the Space Science Institute. “Saturn’s rings are tiny tiny tiny compared to a galaxy, but we see the same physics.”


Keeping a close watch on the outer portion of Saturn's B ring, NASA's Cassini spacecraft records the complex inward and outward movement of the edge of the ring. This ring movement resembles the suspected behavior of spiral disk galaxies.

The position of the outer edge of the B ring, shown here crossing the middle of the frame, varies with time in this concatenation of 301 images taken an average of 1 minute, 50 seconds apart, over the span of about nine hours. The total variation of the edge, from the innermost to outermost locations, is 200 kilometers (120 miles). The eccentric Huygens Ringlet, another very narrow ringlet discovered by Cassini, and the innermost of the bands of ring material in the Cassini Division, a low-density region once thought to be empty, all appear in the top of the frame.

Cassini scientists have determined that the complicated radial variations in the B ring edge are caused by the presence of four scalloped patterns, all independently moving around the ring. One pattern, with two lobes, is present because of the gravitational perturbations from the moon Mimas, which alter the ring particle orbits because of a repetitive configuration of particle and satellite orbital positions known as a Lindblad resonance; this pattern always stays fixed with respect to Mimas.

The other patterns with one, two, and three lobes respectively, travel around the ring with differing speeds and are believed to be natural modes of oscillation of the ring in this vicinity, excited by a process known as "viscous overstability." In this process, the small, random motions of the ring particles feed energy into a wave that propagates outward across the ring from an inner boundary, reflects off the outer edge of the B ring (which becomes distorted as a result), and then travels inward until it reflects off the inner boundary. This continuous back-and-forth reflection is necessary for these wave patterns to grow and become visible as distortions in the outer edge of the B ring.

In supporting these so-called "self-excited" modes, the outer edge of the B ring is behaving the way astronomers believe spiral galaxies behave. However, such modes are not directly observable in galaxies. Cassini's observations of the outer B ring edge constitute the first time such large-scale modes in a broad disk of material have been observed in nature.

The new observations also show two warped regions, including a tall arc of spiky peaks that rise almost two miles above the ring plane. These perturbations may have been sculpted by small moons that migrated across the ring disk, a process believed to be important in shaping planetary systems.

WIRED compilation video

Saturn’s most massive ring, the B ring, has baffled astronomers since the Voyager spacecraft flew by in 1980 and 1981. Those observations showed the B ring was sculpted into a flattened football shape with a sharp outer edge by the moon Mimas. But even in the Voyager images, it was clear the B ring was too complex and chaotic to be shaped by Mimas alone.

Now, in a new analysis published in the Astronomical Journal, thousands of Cassini images gathered over the course of four years have revealed three separate wave patterns that are not driven by any moons, but spring up spontaneously by drawing energy from the small, random motions of ring particles. The waves, which can be hundreds of miles long, keep themselves going by reflecting off the ring’s edges.

“Think of it like waves in a pool,” Porco said. If two kids are hopping up and down at either end of a pool, she says, the waves they send sloshing across the water will pass through each other and reflect off the edge of the pool.

In Saturn’s rings, the waves are more like compressions in a Slinky than water waves, but the physics is similar. “These waves just go back and forth, and keep reflecting until they finally grow large enough so that we can actually see them,” Porco said.

“Normally viscosity, or resistance to flow, damps waves — the way sound waves traveling through the air would die out,” said planetary ring expert Peter Goldreich of Caltech and the Institute for Advanced Study in Princeton, who was not involved in the new study, in a press release. “But the new findings show that, in the densest parts of Saturn’s rings, viscosity actually amplifies waves, explaining mysterious grooves first seen in images taken by the Voyager spacecraft.”

Cassini has also observed similar waves on smaller scales, with wavelengths around 300 feet. Computer models of galaxies and protoplanetary disks around other stars have shown similar randomly generated waves with proportionally larger wavelengths. But because those waves would take hundreds of millions of years to complete one slosh, astronomers can’t observe them directly.

“This is the first time we’ve seen these things in nature,” Porco said. “It underscores the deep, physical connection between what we’re studying at Saturn’s rings, and disk systems across the universe at a very large range of spatial scales.”

Cassini has also snapped pictures of sharp, stalagmite-like peaks at the edge of the B ring that made themselves known by throwing long spiky shadows (below).


Vertical structures, among the tallest seen in Saturn's main rings, rise abruptly from the edge of Saturn's B ring to cast long shadows on the ring in this image taken by NASA's Cassini spacecraft two weeks before the planet's August 2009 equinox.

Part of the Cassini Division, between the B and the A rings, appears at the top of the image, showing ringlets in the inner division.

In this image, Cassini's narrow angle camera captured a 1,200-kilometer-long (750-mile-long) section arcing along the outer edge of the B ring. Here, vertical structures tower as high as 2.5 kilometers (1.6 miles) above the plane of the rings -- a significant deviation from the vertical thickness of the main A, B and C rings, which is generally only about 10 meters (about 30 feet).

Cassini scientists believe that this is one prominent region at the outer edge of the B ring where large bodies, or moonlets, up to a kilometer or more in size, are found. It is possible that these bodies significantly affect the ring material streaming past them and force the particles upward, in a "splashing" manner.

This image and others like it (see PIA11669) are only possible around the time of Saturn's equinox, which occurs every half-Saturn-year, or about every 15 Earth years. The illumination geometry that accompanies equinox lowers the sun's angle to the ring plane and causes structures jutting out of the plane to cast long shadows across the rings. The "season" of equinox allows shadows to appear on the rings in the months before and after equinox, but the actual equinox occurred August 11, 2009, as the sun shone directly edge-on to the ring plane.

This view looks toward the southern, sunlit side of the rings from about 32 degrees below the ring plane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2009. The view was acquired at a distance of approximately 336,000 kilometers (209,000 miles) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 132 degrees. Image scale is 2 kilometers (1 mile) per pixel.

The new study suggests this region of the rings contains small moons that compress the ring material like a soda can and force it upward. This idea is supported by the presence of at least one moonlet, caught during Saturn’s summer equinox when it cast a shadow across the rings.

These moonlets may have migrated across Saturn’s rings, and become trapped in a gravitational resonance with the larger moon Mimas. This process of migration and trapping is exactly how scientists believe the solar system achieved its current architecture.

In this way, Saturn serves as a nearby laboratory to study celestial structures on all scales, from planets to solar systems to galaxies.

“There are basically two shapes in the universe, there’s disks and there’s spheres,” Porco said. “Saturn’s rings allow us to understand one of the two main structures in the universe: a celestial disk system.”

“This is not just a slight addition, it’s something significantly new,” Goldreich told Wired.com. Goldreich and colleagues predicted the presence of these waves in 1985, but the Cassini observations provide the first proof.

“A lot of times, you don’t expect to be around to see whether you made a prediction that worked,” Goldreich said. “I was quite pleased to see it.”
Those 'stagmite' peaks are up to 2.5 km higher than the 10m thick ring plane!

Also posted this week...

Rings around a Crescent

Quote:


A crescent Saturn appears nestled within encircling rings in this Cassini image.

Clouds swirl through the atmosphere of the planet. Prometheus (86 kilometers, 53 miles across) orbits between the main rings and the thin F ring, and this moon appears as a speck above the rings near the middle of the image.

This view looks toward the southern, unilluminated side of the rings from about 3 degrees below the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on Sept. 14, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 890 nanometers. The view was obtained at a distance of approximately 2.6 million kilometers (1.6 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 100 degrees. Image scale on Saturn is 151 kilometers (94 miles) per pixel.
Cassini... bringing the awesome, as always.

All those who believe in telekinesis, raise my hand.
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Moogs
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2010-11-03, 15:48

Freaking incredible images. +1 Burb point.
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curiousuburb
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2010-11-26, 15:40

Oxygen detected in atmosphere of Saturn's moon... Rhea.

Quote:
Quote:
Rhea, the second biggest moon of Saturn, has an atmosphere of oxygen and carbon dioxide, scientists say.

It is incredibly thin, however. The density of O2, for example, is probably about five trillion times less dense than the oxygen that blankets Earth.

The presence of an exosphere, as it is more properly called, was confirmed by instruments on the Cassini probe which orbits the ringed planet and its moons.

The discovery is reported in the online version of Science magazine.

Oxygen exospheres have been seen at Jupiter's moons Europa and Ganymede, but this is the first time such a detection has been made in the Saturnian system.

Presumably, this kind of thing is duplicated billions of times throughout the galaxy. This could be something happening all over the place”
Dr Ben Teolis
Southwest Research Institute
Ben Teolis and colleagues say the tenuous envelope around Rhea is maintained by high-energy particles that constantly bombard the moon's icy surface.

"As the magnetic field rotates around Saturn, particles carried in the field slam into the hemisphere of Rhea that's facing their flow," Dr Teolis from the Southwest Research Institute in San Antonio, US, told BBC News.

"They hit that hemisphere and break water molecules on the surface. The atoms are then rearranging themselves to make O2 molecules, which are sputtered from the surface by additional impacting particles."

It is an ongoing process. As fast as the oxygen is created, energetic processes around Rhea are whipping the O2 molecules out into space.

The mechanism driving the production of carbon dioxide is less obvious, say the researchers.

Some of it, like the O2, could be being produced as a result of high-energy particle impacts. Such CO2 could certainly result if organic compounds are present in the surface ice.

It is possible also that the carbon dioxide was made in deep sub-surface processes and the CO2 is slowly escaping the moon's body.

Rhea is Saturn's second-largest moon, at 1,528km across
It is thought to be composed of a mixture of ice and rock - a frozen dirty snowball
Previous efforts to try to identify an exosphere at Rhea using Earth telescopes and even the remote-sensing instruments on Cassini had failed.
Only by getting up close to Rhea could Cassini make a positive detection.

"What we've been able to do now with Cassini is actually fly through this atmosphere and measure it in situ - to 'sniff' and 'taste' it, and find out what it's made of," said co-author Professor Andrew Coates from the Mullard Space Science Laboratory, University College London, UK.

The probe's ion and neutral mass spectrometer (INMS) measured peak densities of oxygen of about 50 billion molecules per cubic metre . It detected peak densities of carbon dioxide of about 20 billion molecules per cubic metre (about 600 million molecules per cubic foot).

"All this suggests these kinds of exospheres may be very common," said Dr Teolis. "There are different moons at Saturn and at Uranus, for example, which should be massive enough to hold an atmosphere. And, presumably, this kind of thing is duplicated billions of times throughout the galaxy. This could be something happening all over the place."

Other good candidates at Saturn might include the moons Dione and Tethys. No close flybys of Tethys are planned in the remaining years of the Cassini mission, but the probe will get near enough to Dione in December 2011 to try to make a direct detection of an exosphere.

Cassini is a joint venture between the US space agency (Nasa), the European Space Agency (Esa) and the Italian Space Agency (ASI).

Its mission has been extended up until 2017 when it will be commanded to destroy itself by plunging into Saturn's atmosphere.
Not the next moon I would have predicted to have an exosphere, but still cool.
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curiousuburb
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2010-12-16, 08:36

Cassini spots potential Ice Volcano on Titan

Quote:
PASADENA, Calif. – NASA's Cassini spacecraft has found possible ice volcanoes on Saturn's moon Titan that are similar in shape to those on Earth that spew molten rock.
Topography and surface composition data have enabled scientists to make the best case yet in the outer solar system for an Earth-like volcano landform that erupts in ice. The results were presented today at the American Geophysical Union meeting in San Francisco.


Flyover of Sotra Facula, Titan . Full-Res: PIA13695
QuickTime, screen size: 640x360 (48 MB) MPEG-4, screen size: 1280x720 (80 MB) QuickTime, screen size: 1280x720 (145 MB) Window Media Video (74 MB) Flash Video (18 MB) MPEG-4, screen size: 640x360 (29 MB) MPEG-4, screen size: 640x360 (37 MB) Window Media Video (44 MB)

This movie is based on data from NASA's Cassini spacecraft and shows a flyover of an area of Saturn’s moon Titan known as Sotra Facula. Scientists believe Sotra is the best case for an ice volcano -- or cryovolcano -- region on Titan. The flyovershows two peaks more than 1,000 meters (3,000 feet) tall and multiple craters as deep as 1,500 meters (5,000 feet). It also shows finger-like flows. All of these are land features that indicate cryovolcanism. The 3-D topography comes from Cassini’s radar instrument. Topography has been vertically exaggerated by a factor of 10. The false color in the initial frames shows different compositions of surface material as detected by Cassini’s visual and infrared mapping spectrometer. In this color scheme, dunes tend to look relatively brown-blue. Blue suggests the presence of some exposed ice. Scientists think the bright areas have an organic coating that hides the ice and is different and lighter than the dunes. The finger-like flows appear bright yellowish-white, like the mountain and caldera. The second set of colors shows elevation, with blue being lowest and yellow and white being the highest. Dunes here appear blue because they tend to occupy low areas. The finger-like flows are harder to see in the elevation data, indicating that they are thin, maybe less than about 100 meters (300 feet) thick.

This image shows the location of an area known as Sotra Facula on Saturn’s moon Titan. The black and white swaths show data obtained by the radar instrument on NASA’s Cassini spacecraft.
"When we look at our new 3-D map of Sotra Facula on Titan, we are struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki in Iceland and even some small volcanic cones and flows near my hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping work, and is a Cassini radar team member and geophysicist at the U.S. Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also called cryovolcanoes, exist on ice-rich moons, and if they do, what their characteristics are. The working definition assumes some kind of subterranean geological activity warms the cold environment enough to melt part of the satellite's interior and sends slushy ice or other materials through an opening in the surface. Volcanoes on Jupiter's moon Io and on Earth spew silicate lava.

Some cryovolcanoes bear little resemblance to terrestrial volcanoes, such as the tiger stripes at Saturn's moon Enceladus, where long fissures spray jets of water and icy particles that leave little trace on the surface. At other sites, eruption of denser materials might build up volcanic peaks or finger-like flows. But when such flows were spotted on Titan in the past, theories explained them as non-volcanic processes, such as rivers depositing sediment. At Sotra, however, cryovolcanism is the best explanation for two peaks more than 1,000 meters (3,000 feet) high with deep volcanic craters and finger-like flows.

"This is the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite," said Jeffrey Kargel, a planetary scientist at the University of Arizona, Tucson. "It's possible the mountains are tectonic in origin, but the interpretation of cryovolcano is a much simpler, more consistent explanation."

Kirk and colleagues analyzed new Cassini radar images. His USGS group created the topographic map and 3-D flyover images of Sotra Facula. Data from Cassini's visual and infrared mapping spectrometer revealed the lobed flows had a composition different from the surrounding surface. Scientists have no evidence of current activity at Sotra, but they plan to monitor the area.

"Cryovolcanoes help explain the geological forces sculpting some of these exotic places in our solar system," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "At Titan, for instance, they explain how methane can be continually replenished in the atmosphere when the sun is constantly breaking that molecule down."

Cassini launched Oct. 15, 1997, and began orbiting Saturn in 2004. Saturn has more than 60 known moons, with Titan being the largest. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency (ASI). JPL manages the mission for NASA's Science Mission Directorate at the agency's Headquarters in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and ASI, working with team members from the U.S. and several European countries. The visual and infrared mapping spectrometer was built by JPL, with a major contribution by ASI. The visual and infrared mapping spectrometer science team is based at the University of Arizona, Tucson. JPL is a division of the California Institute of Technology in Pasadena.
For more information about the Cassini mission, visit: http://www.nasa.gov/cassini.
BBC story (with audio interview which may be UK only)
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curiousuburb
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2011-03-09, 09:46

5.6k Saturn Photographic Animation from Cassini Images



No CGI, all real images. An IMAX work in progress from the OutsideIn project.

Quote:
Ultimately, the film will recreate a journey through the solar system using only actual images taken by the robotic spacecraft exploring our solar system. Here, you can zoom towards Saturn, through the rings and fly past some of its moons.
Watch it full screen in HD and feel like you're there.

Shweet!

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Moogs
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2011-03-09, 10:57

It's beautiful but I don't understand how the ring images can possibly be real. The rings are made of dust and rocks and boulders, right?

But the pass-though makes it look like a completely uniform haze with no solid stuff floating around. Would they even fly the spacecraft through the rings (for the reason stated above)??

Also at one point in the IMAX part the ring has a very unnatural looking termination that doesn't seem to match the light source. Like a hard-edged "cut" that doesn't seem to have any natural fade to it or matching component on the other side of the planet (you can see it in the image above). What am I missing?

...into the light of a dark black night.
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Maciej
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2011-03-09, 12:16

Quote:
Originally Posted by Moogs View Post
What am I missing?
You're not the only one. I'm confused by all the stuff you posted above too. Maybe they flew it right through one of the gaps between the rings - they must be fairly tight to form such ring structures.

User formally known as Sh0eWax
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curiousuburb
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2011-03-09, 14:12

Cassini actually flew through the rings during it's orbital insertion (in one of the gaps). It has since crossed the plane a few times.

The Cassini imaging team even made their own movie of a 2007 ring plane crossing.



Crossing isn't in a gap this time, but you still get a sense they're only a maximum of about 10 metres thick (often only dust sized), and see lots of moons on show.

More details on the rings can be found here

All those who believe in telekinesis, raise my hand.

Last edited by curiousuburb : 2011-03-09 at 14:22.
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curiousuburb
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2011-04-05, 06:25

Ring 'ripples' caused by comet

Quote:

Scientists say that strange ripples observed in the ring systems of Saturn and Jupiter were caused by comets.

The ripples, which the researchers say resemble the undulations of corrugated metal, were detected in both Saturn's rings and in Jupiter's lesser-known rings.

Alternating light and dark bands in Saturn's C ring captured by the Cassini spacecraft in 2009
The ripples in Jupiter's rings are believed to have been caused by the comet Shoemaker-Levy 9, which struck the planet in 1994. Details are published in two separate papers in the journal Science.

The researchers analysed images of Jupiter's rings taken by the Galileo spacecraft in 1996 and 2000 and by the New Horizons probe in 2007. They also looked at images of Saturn's rings taken by the Cassini spacecraft during 2009.

What they found were undulations that the researchers liken to a corrugated tin roof, which when lit from a low angle, appear as alternating dark and light bands.

This corrugation was found across Saturn's entire C ring, stretching for thousands of kilometres. It appeared to be part of a similar pattern observed previously in the fainter D ring. At least two separate spirals were meanwhile detected in Jupiter's rings.

They researchers believe they were been caused by debris, most likely from a comet, impacting rings, and tilting them.

"The material passes through the ring and basically causes the entire ring to be slightly tilted with respect to the planet's equatorial plane, and then it shears out to form this spiral pattern," said Dr Matthew Hedman of Cornell University in New York.
"There was the eureka moment when we realised we had a smoking gun”

Dr Mark Showalter
SETI Institute
Over time, the corrugated spiral became more tightly wound, as the gravity of the planet pulled the rings back into alignment. However, completing the process could take decades, the researchers estimate.

The team was then able to rewind the process using mathematical models to give an estimated date of the impact event. For Saturn, they arrived at a point in 1983, but have not yet found a possible candidate comet.

With Jupiter, they detected at least two spirals and so possibly two impact events. When they wound back the process for one of the spirals, they reached a point in 1994, the same year of the Shoemaker-Levy 9 impact.

... continues
Thankfully, it wasn't a Son'a collector.


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curiousuburb
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2017-04-28, 08:19

After a final Earth-Moon selfie between the rings from one 1.4 Billion km, Cassini has begun Grand Finale manoeuvre... a series of 22 ring plane crossings and decreasing orbits before kamikaze impact into Saturn on September 15

image link/details

Grand Finale fact sheet

Final pass of Titan went the other day and first ring plane crossing between the rings and Saturn successfully accomplished mid week.

So much science... so many awesome images... sad to think there's so little time left

Go Cassini!

All those who believe in telekinesis, raise my hand.
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709
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2017-04-28, 09:54

I forget where I read this, but during these final flybys Cassini is so close to Saturn and going so fast that it's impossible for it to get a color photo (!). Apparently the 20-year-old kit has to switch between its Red, Green and Blue filters for us to create a final combined color photo, and it's going too fast to focus on one point long enough. Thought that was a neat bit of info.

Imagine the photos we'll be getting from Europa in a decade even with the cellphone camera tech we have now. Amazing.

So it goes.
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curiousuburb
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2017-09-09, 12:26

In the latest news, one week left for Cassini to live...



Old School Posters mark the date



Groovy animations imagine the journey



With sadness we celebrate the final kamikaze dive and breakup



Today/Tonight, Sept. 9 -- Cassini will make the last of 22 passes between Saturn itself and its rings -- closest approach is 1,044 miles (1,680 kilometers) above the clouds tops.

Still remaining are final close approaches to its most celebrated targets... its mightiest and most mysterious of moons... Titan (shrouded with Methane-rich atmosphere) and Enceladus (home to geysers laden with life's precursors)

Come Sept. 15 and Cassini will plunge into Saturn in an act of planetary protection strangely reminiscent of the mythological God consuming its own children

But the Science will live on

All those who believe in telekinesis, raise my hand.
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curiousuburb
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2017-09-15, 03:32

Raise a glass, shed a tear, etc... today is Cassini's swan song and kamikaze dive into Saturn's atmosphere.

Download the "Saturn through the eyes of Cassini" e-Book here

Watch the NASA "Previews Mission End" Pre-Finale Press Conference on YouTube here

Read about the details, "By the Numbers"

And for those who want to watch the Finale itself in 3 and a half hours from now, see here

All those who believe in telekinesis, raise my hand.
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curiousuburb
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2017-09-15, 05:54

One hour and counting... Thanks for the memories Cassini 🚀🛰

Live coverage about to start on NASA TV Public channel
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curiousuburb
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2017-09-15, 06:26

LOS about 30 minutes from now...
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