Category: Saturn

Saturn’s F-Ring with Pandora, one of its shepherd moons. Image credit: NASA/JPL/SSI. Click to enlarge.
The shepherd moon, Pandora, is seen here alongside the narrow F ring that it helps maintain. Pandora is 84 kilometers (52 miles) across.

Cassini obtained this view from about four degrees above the ringplane. Captured here are several faint, dusty ringlets in the vicinity of the F ring core. The ringlets do not appear to be perturbed to the degree seen in the core.

The appearance of Pandora here is exciting, as the moon’s complete shape can be seen, thanks to reflected light from Saturn, which illuminates Pandora’s dark side. The hint of a crater is visible on the dark side of the moon.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 4, 2005, at a distance of approximately 967,000 kilometers (601,000 miles) from Pandora and at a Sun-Pandora-spacecraft, or phase, angle of 117 degrees. The image scale is 6 kilometers (4 miles) 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 team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. For additional images visit the Cassini imaging team homepage http://ciclops.org.

Original Source: NASA/JPL/SSI News Release

Infrared image of Titan taken by Cassini during its Oct. 26, 2004 flyby. Image credit: NASA/JPL/SSI. Click to enlarge.
A recent flyby of Saturn’s hazy moon Titan by the Cassini spacecraft has revealed evidence of a possible volcano, which could be a source of methane in Titan’s atmosphere.

Images taken in infrared light show a circular feature roughly 30 kilometers (19 miles) in diameter that does not resemble any features seen on Saturn’s other icy moons. Scientists interpret the feature as an “ice volcano,” a dome formed by upwelling icy plumes that release methane into Titan’s atmosphere. The findings appear in the June 9 issue of Nature.

“Before Cassini-Huygens, the most widely accepted explanation for the presence of methane in Titan’s atmosphere was the presence of a methane-rich hydrocarbon ocean,” said Dr. Christophe Sotin, distinguished visiting scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“The suite of instruments onboard Cassini and the observations at the Huygens landing site reveal that a global ocean is not present,” said Sotin, a team member of the Cassini visual and infrared mapping spectrometer instrument and professor at the Universit? de Nantes, France.

“Interpreting this feature as a cryovolcano provides an alternative explanation for the presence of methane in Titan’s atmosphere. Such an interpretation is supported by models of Titan’s evolution,” Sotin said.

Titan, Saturn’s largest moon, is the only known moon to have a significant atmosphere, composed primarily of nitrogen, with 2 to 3 percent methane. One goal of the Cassini mission is to find an explanation for what is replenishing and maintaining this atmosphere. This dense atmosphere makes the surface very difficult to study with visible-light cameras, but infrared instruments like the visual and infrared mapping spectrometer can peer through the haze. Infrared images provide information about both the composition and the shape of the area studied.

The highest resolution image obtained by the visual and infrared mapping spectrometer instrument covers an area 150 kilometers square (90 miles) that includes a bright circular feature about 30 kilometers (19 miles) in diameter, with two elongated wings extending westward. This structure resembles volcanoes on Earth and Venus, with overlapping layers of material from a series of flows. “We all thought volcanoes had to exist on Titan, and now we’ve found the most convincing evidence to date. This is exactly what we’ve been looking for,” said Dr. Bonnie Buratti, team member of the Cassini visual and infrared mapping spectrometer at JPL.

In the center of the area, scientists clearly see a dark feature that resembles a caldera, a bowl-shaped structure formed above chambers of molten material. The material erupting from the volcano might be a methane-water ice mixture combined with other ices and hydrocarbons. Energy from an internal heat source may cause these materials to upwell and vaporize as they reach the surface. Future Titan flybys will help determine whether tidal forces can generate enough heat to drive the volcano, or whether some other energy source must be present. Black channels seen by the European Space Agency’s Huygens probe, which piggybacked on Cassini and landed on Titan’s surface in January 2005, could have been formed by erosion from liquid methane rains following the eruptions.

Scientists have considered other explanations. They say the feature cannot be a cloud because it does not appear to move and it is the wrong composition. Another alternative is that an accumulation of solid particles was transported by gas or liquid, similar to sand dunes on Earth. But the shape and wind patterns don’t match those normally seen in sand dunes.

The data for these findings are from Cassini’s first targeted flyby of Titan on Oct. 26, 2004, at a distance of 1,200 kilometers (750 miles) from the moon’s surface.

The visual and infrared mapping spectrometer instrument can detect 352 wavelengths of light from 0.35 to 5.1 micrometers. It measures the intensities of individual wavelengths and uses the data to infer the composition and other properties of the object that emitted the light; each chemical has a unique spectral signature that can be identified.

Forty-five flybys of Titan are planned during Cassini’s four-year prime mission. The next one is Aug. 22, 2005. Radar data of the same sites observed by the visual and infrared mapping spectrometer may provide additional information.

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

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona.

Original Source: NASA/JPL/SSI News Release

Cassini’s beautiful view of Saturn, looking through its rings. Image credit: NASA/JPL/SSI. Click to enlarge.
In this fabulous close-up, Cassini peers directly through regions of the A, B and C rings (from top to bottom here) to glimpse shadows of the very same rings cast upon the planet’s atmosphere. Near the top, shadows cast by ringlets in the Cassini division (center) look almost like a photo negative.

This type of image helps scientists probe the rings’ structure in detail and provides information about the density of their constituent particles.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 26, 2005, at a distance of approximately 2.3 million kilometers (1.4 million miles) from Saturn. The image scale is 14 kilometers (9 miles) 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 team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For additional images visit the Cassini imaging team homepage http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Titan and its strange spot viewed in different wavelengths. Image credit: NASA/JPL/SSI. Click to enlarge.
Saturn’s moon Titan shows an unusual bright spot that has scientists mystified. The spot, approximately the size and shape of West Virginia, is just southeast of the bright region called Xanadu and is visible to multiple instruments on the Cassini spacecraft.

The 483-kilometer-wide (300-mile) region may be a “hot” spot — an area possibly warmed by a recent asteroid impact or by a mixture of water ice and ammonia from a warm interior, oozing out of an ice volcano onto colder surrounding terrain. Other possibilities for the unusual bright spot include landscape features holding clouds in place or unusual materials on the surface.

“At first glance, I thought the feature looked strange, almost out of place,” said Dr. Robert H. Brown, team leader of the Cassini visual and infrared mapping spectrometer and professor at the Lunar and Planetary Laboratory, University of Arizona, Tucson. “After thinking a bit, I speculated that it was a hot spot. In retrospect, that might not be the best hypothesis. But the spot is no less intriguing.”

The Cassini spacecraft flew by Titan on March 31 and April 16. Its visual and infrared mapping spectrometer, using the longest, reddest wavelengths that the spectrometer sees, observed the spot, the brightest area ever observed on Titan.

Cassini’s imaging cameras saw a bright, 550-kilometer-wide (345-mile) semi-circle at visible wavelengths at this same location on Cassini’s December 2004 and February 2005 Titan flybys. “It seems clear that both instruments are detecting the same basic feature on or controlled by Titan’s surface,” said Dr. Alfred S. McEwen, Cassini imaging team scientist, also of the University of Arizona. “This bright patch may be due to an impact event, landslide, cryovolcanism or atmospheric processes. Its distinct color and brightness suggest that it may have formed relatively recently.”

Other bright spots have been seen on Titan, but all have been transient features that move or disappear within hours, and have different spectral (color) properties than this feature. This spot is persistent in both its color and location. “It’s possible that the visual and infrared spectrometer is seeing a cloud that is topographically controlled by something on the surface, and that this weird, semi-circular feature is causing this cloud,” said Dr. Elizabeth Turtle, Cassini imaging team associate, also from the Lunar and Planetary Laboratory.

“If the spot is a cloud, then its longevity and stability imply that it is controlled by the surface. Such a cloud might result from airflow across low mountains or outgassing caused by geologic activity,” said Jason Barnes, a postdoctoral researcher working with the visual and infrared mapping spectrometer team at the University of Arizona.

The spot could be reflected light from a patch of terrain made up of some exotic surface material. “Titan’s surface seems to be mostly dirty ice. The bright spot might be a region with different surface composition, or maybe a thin surface deposit of non-icy material,” Barnes added.

Scientists have also considered that the spot might be mountains. If so, they’d have to be much higher than the 100-meter-high (300-foot) hills Cassini’s radar altimeter has seen so far. Scientists doubt that Titan’s crust could support such high mountains.

The visual and infrared mapping spectrometer team will be able to test the hot spot hypothesis on the July 2, 2006, Titan flyby, when they take nighttime images of the same area. If the spot glows at night, researchers will know it’s hot.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. For additional images visit the visual and infrared mapping spectrometer page at http://wwwvims.lpl.arizona.edu and the Cassini imaging team homepage http://ciclops.org .

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 visual and infrared mapping spectrometer team is based at the University of Arizona. The imaging team is based at the Space Science Institute in Boulder, Co.

Original Source: NASA/JPL News Release

Saturn viewed by Chandra in the X-Ray spectrum during a solar flare. Image credit: Chandra. Click to enlarge.
When it comes to mysterious X-rays from Saturn, the ringed planet may act as a mirror, reflecting explosive activity from the sun, according to scientists using NASA’s Chandra X-ray Observatory.

The findings stem from the first observation of an X-ray flare reflected from Saturn’s low-latitudes, the region that correlates to Earth’s equator and tropics.

Dr. Anil Bhardwaj, a planetary scientist at NASA’s Marshall Space Flight Center (MSFC), Huntsville, Ala., led the study team. The study revealed Saturn acts as a diffuse mirror for solar X-rays.

Counting photons, particles that carry electromagnetic energy including X-rays, was critical to this discovery. Previous studies revealed Jupiter, with a diameter 11 times that of Earth, behaves in a similar fashion. Saturn is about 9.5 times larger than Earth. It is twice as far from Earth as Jupiter.

“The bigger the planet and nearer to the sun, the more solar photons it will intercept; resulting in more reflected X-rays.” Bhardwaj said. “These results imply we could use giant planets like Jupiter and Saturn as remote-sensing tools. By reflecting solar activity back to us, they could help us monitor X-ray flaring on portions of the sun facing away from Earth’s space satellites.”

Massive solar explosions called flares often accompany coronal mass ejections, which emit solar material and a magnetic field. When directed toward Earth, these ejections can wreak havoc on communications’ systems from cell phones to satellites.

Even as the research appeared to solve one mystery, the source of Saturn’s X-rays, it fueled long standing questions about magnetic fields. Of the three magnetic planets in our solar system, Jupiter and Earth emit two general types of X rays, auroral emissions from polar regions and disk emissions from low latitudes. No research has observed unambiguous signatures of auroral X-ray emissions on Saturn.

“We were surprised to find no clear evidence of auroral X-ray emissions during our observations,” Bhardwaj said. “It is interesting to note that even as research solves some mysteries, it confirms there is much more we have to learn.”

The research appeared in the May 10, 2005 issue of Astrophysical J. Letters. the research team also included Ron Elsner of MSFC; Hunter Waite of the University of Michigan, Ann Arbor; Randy Gladstone of the Southwest Research Institute, San Antonio, Texas; Thomas Cravens of the University of Kansas, Lawrence; and Peter Ford from the Massachusetts Institute of Technology, Cambridge.

Bhardwaj is working at MSFC as a National Research Council scholar. MSFC manages the Chandra program for NASA’s Science Mission Directorate in Washington. Northrop Grumman of Redondo Beach, Calif., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Original Source: NASA News Release

Saturn’s atmosphere makes the rings look like they’re bending just as they pass behind the planet. Image credit: NASA/JPL/SSI. Click to enlarge.
Saturn’s rings appear strangely warped in this view of the rings seen through the upper Saturn atmosphere.

The atmosphere acts like a lens in refracting (bending) the light reflected from the rings. As the rings pass behind the overexposed limb (edge) of Saturn as seen from Cassini, the ring structure appears to curve downward due to the bending of the light as it passes through the upper atmosphere.

This image was obtained using a near-infrared filter. The filter samples a wavelength where methane gas does not absorb light, thus making the far-off rings visible through the upper atmosphere.

By comparing this image to similar ones taken using filters where methane gas does absorb, scientists can estimate the vertical profile of haze and the abundance of methane in Saturn’s high atmosphere.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 14, 2005, through a filter sensitive to wavelengths of infrared light centered at 938 nanometers and at a distance of approximately 197,000 kilometers (123,000 miles) from Saturn. The image scale is 820 meters (2,680 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 team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For additional images visit the Cassini imaging team homepage http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Cassini image of Saturn’s rings enhanced in false colours. Image credit: NASA/JPL/SSI. Click to enlarge.
The Cassini spacecraft has obtained the most detailed look ever at Saturn’s rings, including the B ring, which has eluded previous robotic explorers. Its structure seems remarkably different from its two neighbors, rings A and C.

The origin of Saturn’s rings is a mystery. The rings are an enormous, complex structure. From edge-to-edge, the ring system would not even fit in the distance between Earth and the Moon. The seven main rings are labeled in the order they were discovered. From the planet outward, they are D, C, B, A, F, G and E.

During a recent radio experiment, Cassini mapped this structure with clarity never before available. This is the first of many such observations Cassini will be conducting over the summer.

“The structure of those remarkable rings is a sight to behold. All ring features appear to be populated by a broad range of particle sizes that extend to many meters in diameter at the upper end,” said Dr. Essam Marouf, Cassini radio science team member and professor of electrical engineering, San Jose State University, San Jose, Calif.

Marouf said that at the lower end, particles of about 5 centimeters (roughly 2 inches) in diameter or less seem to be scarce in ring B and inner ring A. In rings C and outer ring A, particles of less than about 5 centimeters (2 inches) in diameter seem to be abundant.

Cassini found that the inner and outer parts of ring B contain rings that are hundreds of kilometers wide (hundreds of miles) and vary greatly in the amount of material they contain. A thick, 5,000-kilometer-wide (3,100-mile) core contains several bands with ring material that is nearly four times as dense as that of ring A and nearly 20 times as dense as that of ring C.

The dramatically varying structure of ring B is in sharp contrast to the relatively flat structure of ring A or the gentle, wavy structure of ring C, where many dense, narrow and sharp-edged ringlets permeate its outer part.

Cassini also detected more than 40 wavy features called “density waves” in ring A, many near its outer region, close to the moons orbiting just outside the ring. The density wave observations will tell more about the ring surface mass density, its vertical thickness and other physical properties.

“A marvelous array of waves, caused by gravitational interactions with nearby moons, has been uncovered throughout ring A,” said Marouf. “We also see a major density wave in the dense ring B. Some of these waves have been seen in Voyager and other Cassini observations, but not in this large number and not with this exceptional clarity.”

Cassini conducted this first radio occultation observation of Saturn’s rings, atmosphere and ionosphere on May 3, 2005. An occultation means that if you watch Cassini from Earth, Cassini would appear occulted, or hidden, behind the rings. During a radio occultation, Cassini sends a radio signal from the spacecraft through the rings to Earth. Scientists then watch how the strength of the radio signal is affected as the signal passes through ring material. The denser a ring is, the weaker the signal received. The experiment helps scientists map the distribution of the amount of ring material and determine the ring particle sizes.

The occultation was the first ever to use three radio signals of different frequencies (called Ka, X and S) transmitted simultaneously from a spacecraft to Earth-receiving stations of NASA’s Deep Space Network. Ring particles of different sizes affect each frequency differently.

The Cassini tour was specifically designed to optimize the geometry of the first radio occultation experiment and seven other occultations scheduled from May to September 2005. These observations are at the heart of Cassini’s fundamental science objectives of characterizing and understanding Saturn and its ring system. During its lifetime, Cassini will obtain 20 radio occultations and 80 stellar occultations, providing far more detailed knowledge of the ring structures.

For images and information on the Cassini mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

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 Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL.

Original Source: NASA/JPL News Release

Saturn’s icy moon Enceladus above the rings. Image credit: NASA/JPL/SSI. Click to enlarge.
Saturn’s icy moon Enceladus hovers above Saturn’s exquisite rings in this color view from Cassini. The rings, made of nearly pure water ice, have also become somewhat contaminated by meteoritic dust during their history, which may span several hundred million years. Enceladus shares the rings’ nearly pure water ice composition, but appears to have eluded dust contamination through resurfacing processes that scientists are still trying to understand. Enceladus is 505 kilometers (314 miles) across.

Dust affects the rings’ color, while differences in brightness are attributable to varying particle sizes and concentrations.

The images for this natural color view were taken with the Cassini spacecraft narrow-angle camera on April 5, 2005, at a distance of approximately 2.2 million kilometers (1.4 million miles) from Saturn through red, green and blue spectral filters. The image scale is 13 kilometers (8 miles) 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 team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For additional images visit the Cassini imaging team homepage http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Mosaic of Huygens’ Titan images showing its landing spot. Image credit: ESA. Click to enlarge.
As the large amount of data collected by the ESA Huygens probe during its descent onto Titan is being processed, new views of this fascinating world become available.

The Descent Imager Spectral Radiometer (DISR) team have now produced the first complete ?stereographic? and ?gnomonic? mosaic images. Using special image projection techniques, the team combined a series of images captured by Huygens while rotating on its axis at an altitude of about 20 kilometres.

The DISR on board Huygens took its series of photographs of the ever-approaching surface in sets of three, or ?triplets?, as it dropped through Titan?s atmosphere on 14 January this year. The images sent back to Earth partially overlap, due to the probe?s rotation during the descent and due to the overlap between the fields of view of the different cameras.

DISR scientists are studying these images for similarities, such as physical features common to more than one image, and are constructing ?mosaics?, like jigsaw puzzles.

There are many different ways of rendering three-dimensional objects into two dimensions. Different kinds of projections for maps or photographs are able to represent realistically things like size, areas, distances and perspective. One particular kind of projection used for spheres in two dimensions (for example on some maps of Earth or the celestial sphere) is ?stereographic? projection.

A ?gnomonic? projection has also been produced, and this tends to make the surface appear as if it was flat. This type of projection is often found on maps used by navigators and aviators in determining the shortest distance between two points. However there is a lot of distortion of scale at the outer edges of gnomonic projections.

On the stereographic view, like that through a ?fish-eye? lens, the bright area to the north (top of the image) and west is higher than the rest of the terrain, and covered in dark lines that appear to be drainage channels. These lead down to what appears to be a shoreline with river deltas and sand bars.

The current interpretation of these lines is that they are cut by flowing liquid methane. Some of them may have been produced by precipitation run-off, producing a dense network of narrow channels and features with sharp branching angles. Some others may have been produced by sapping or sub-surface flows, giving shape to short stubby channels that join at 90 degree angles.

The largest run off channel starts at about the 12 o?clock position from an inlet on the shoreline and stretches to the left. The largest sapping channel starts at the 9 o? clock position and goes in a straight line up and left. The dark wide corridor to the west just below the sapping channel appears to be a major flow channel that empties into the mud flats of the lakebed.

The bright shapes to the north-east and east look to be ridges of ice gravel that are slightly higher than the flats around them, and the probe landing is believed to be just south-west of the semi-circular shape. The light and dark areas to the south are still of unknown nature.

On the gnomonic projection, the landing site is approaching and the surface features become sharper. North is at the top of the image. From lower left to upper right appears to be a ridge of ice boulders projecting through the darker lakebed material.

They are thought to slow the major flow from the west and cause the fluid to pond on the north-west side of the image, causing sedimentation of the dark material. Seepage between the boulders cuts the sediment into channels as the fluid continues to the south-east.

The members of the Huygens DISR instrument team are based throughout the USA and Europe, with the largest contributing groups from the University of Arizona, USA, the Max Planck Institute, Germany, and the Paris Observatory, Meudon, France.

Original Source: ESA News Release

Image of Titan’s thick hazy atmosphere which is surprisingly similar to the early Earth. Image credit: NASA/JPL/SSI. Click to enlarge.
Titan’s atmospheric winds, temperature and mixing have been revealed by new observations from the Cassini spacecraft. The thick atmosphere of Saturn’s giant moon is rich in organic compounds, whose chemistry may be similar to that which occurred on Earth before the emergence of life.

“Titan is not just a dot in the sky; these new observations show that Titan is a rich, complex world much like the Earth in some ways,” said Dr. Michael Flasar of NASA’s Goddard Space Flight Center, Greenbelt, Md., Composite Infrared Spectrometer instrument (CIRS) principal investigator. Flasar is lead author of a paper on this research published May 13 in the Journal Science.

The CIRS science team found evidence for an isolated polar vortex similar to one that occurs on Earth. CIRS’ observations indicated that strong winds circulating around Titan’s north pole isolate the atmosphere there during the polar night. Mixing of the polar region with the lower latitude regions of the atmosphere is inhibited during this time. On Earth, the south polar atmosphere is isolated for months during the long Antarctic winter allowing the formation of polar stratospheric clouds. Normally inert chlorine compounds (such as chlorine nitrate) undergo chemical reactions on the cloud crystals that free molecular chlorine. In the spring, sunlight decomposes the molecular chlorine, leading to the famous annual Antarctic ?ozone hole?. Titan’s atmosphere contains no ozone; however the CIRS results show that a large part of its atmosphere is isolated during the polar night, and that could allow unusual and complex chemistry to occur.

Like Earth, Titan’s axis of rotation is tilted, so its poles also experience a long night during winter. The polar winter on Titan is many earth years long, because Saturn orbits the sun once in almost 30 years. Currently it is early winter in Titan’s northern hemisphere. The CIRS team found significant temperature differences between Titan’s north pole and the equator. The team used this observation to derive the speed of circumpolar winds around the north pole. The team believes these winds are isolating the atmosphere around Titan’s north pole because the CIRS data showed that the concentration of several heavy organic (carbon-containing) molecules is highest there.

Heavy organic molecules form naturally in Titan’s atmosphere, blanketing the moon with an orange haze. Titan?s atmosphere consists of about 98 percent nitrogen with most of the remainder being methane. When these molecules rise to the upper atmosphere, they are broken apart by sunlight and the fragments form heavier organic molecules like propane, ethane, acetylene, hydrogen cyanide, and even more complex molecules. Because the stratospheric air over the winter pole is cold, it sinks and brings down the heavy organic compounds that formed higher up. If the air over Titan’s north pole is isolated during the winter, the heavy organics should build up in the stratosphere over the season. This is just what the CIRS team is seeing.

“We don’t know if there are even more similarities to Earth’s ozone hole process, like polar clouds that react with molecules in the atmosphere, simply because we haven’t seen them yet,” said Flasar. “But we wouldn’t be surprised to discover them, nor would we be surprised to find that Titan has some unique twists of its own. This is what makes science so exciting. Nature is too rich for us to predict exactly what we will find when we go exploring.”

The research was funded by NASA and the European Space Agency. 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 Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C.

Original Source: NASA News Release