Category: Saturn

Saturn’s bright moon Enceladus hovers here, in front of a rings darkened by Saturn’s shadow. Enceladus is 505 kilometers (314 miles) across.

This view is from less than one degree beneath the ring plane. If seen from directly beneath the rings, the planet’s giant shadow would appear as an elongated half-ellipse; the acute viewing angle makes the shadow look more like a strip here. (See The Greatest Saturn Portrait…Yet, for a different viewing angle). The dark shadow first takes a bite out of the rings at the right, where the distant, outermost ring material appears to taper and fade.

Ring features visible in this image from the outer ring edge inward include: the A ring, the Cassini Division and the B ring. The C ring is the darker region that dominates the rings here. The two gaps visible near the center and below the left of the center are the Titan Gap, about 77,800 kilometers (48,300 miles) from Saturn, and an unnamed gap about 75,800 kilometers (47,100 miles) from the planet.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 7, 2005, at a distance of approximately 1.1 million kilometers (650,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 30 degrees. The pixel 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

This map of Titan’s surface illustrates the regions that will be imaged by Cassini during the spacecraft’s close flyby of the smog-enshrouded moon on April 16, 2005. At closest approach, the spacecraft is expected to pass approximately 1,025 kilometers (640 miles) above the moon’s surface.

The colored lines delineate the regions that will be imaged at differing resolutions.

Images from this encounter will add to those taken during the March 31, 2005, flyby and improve the moderate resolution coverage of this region. The imaging coverage will include the eastern portion of territory observed by Cassini’s radar instrument in October 2004 and February 2005, and will provide a way to compare the surface as viewed by the different instruments. Such comparisons (see PIA06222) will provide insight into the nature of Titan’s surface.

The higher-resolution (yellow boxes) have been spread out around a central mosaic in order to maximize coverage of this region by the visual and infrared mapping spectrometer which will be observing simultaneously with the cameras of the imaging science subsystem.

The map shows only brightness variations on Titan’s surface (the illumination is such that there are no shadows and no shading due to topographic variations). Previous observations indicate that, due to Titan’s thick, hazy atmosphere, the sizes of surface features that can be resolved are a few times larger than the actual pixel scale labeled on the map.

The images for this global map were obtained using a narrow band filter centered at 938 nanometers — a near-infrared wavelength (invisible to the human eye). At this wavelength, light can penetrate Titan’s atmosphere to reach the surface and return through the atmosphere to be detected by the camera. The images have been processed to enhance surface details.

It is currently northern winter on Titan, so the moon’s high northern latitudes are not illuminated, resulting in the lack of coverage north of 35 degrees north latitude.

At 5,150 kilometers (3,200 miles) across, Titan is one of the solar system’s largest moons.

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

During a close flyby of Titan on March 31, 2005, Cassini’s cameras got their best view to date of the region east of the bright Xanadu Regio. This mosaic consists of several frames taken by the narrow-angle camera (smaller frames) put together with an image taken by the wide-angle camera filling in the background. It reveals new detail of dark expanses and the surrounding brighter terrain.

Some of the features seen here are reminiscent of those seen elsewhere on Titan, but the images also reveal new features, which Cassini scientists are working to understand.

In the center of the image (and figure A at bottom) lies a bright area completely surrounded by darker material. The northern boundary of the bright “island” is relatively sharp and has a jagged profile, resembling the now-familiar boundary on the western side of Xanadu (see PIA06159). The profile of the southern boundary is similar. However, streamers of bright material extend southeastward into the dark terrain. At the eastern end of the bright “island” lies a region with complex interconnected dark and bright regions (see figure B).

To the south, the bright terrain is cut by fairly straight dark lines. Their linearity and apparently angular intersections suggest a tectonic influence, similar to features in seen in the bright terrain west of Xanadu (see PIA06158).

The camera’s near-infrared observations cover ground that was also seen by Cassini’s synthetic aperture radar in October 2004 and February 2005. Toward the northeastern edge of the dark material a dark, circular spot in the middle of a bright feature (see figure C) is an approximately 80-kilometer-wide (50-mile) crater identified in the February 2005 radar data (see PIA07368 for the radar image).

The resolution of this new image is lower but sufficient to reveal important similarities and differences between the two observations. Part of the crater floor is quite dark compared to the surrounding material at near-infrared wavelengths. This observation is consistent with the hypothesis that the dark material consists of complex hydrocarbons that have precipitated from the atmosphere and collected in areas of low elevation. At radar wavelengths the crater floor is much more uniform and there also are brightness differences seen by these two instruments outside of the crater. Such comparisons give Cassini scientists important clues about the roughness and composition of the surface material on Titan.

Another interesting comparison is the “dark terrain” with small bright features as seen by the radar (see PIA07367) and the essentially inverted pattern (bright with small dark features) seen by the imaging science subsystem cameras. In the mosaic, this area is in the top left narrow-angle camera image.

Within the bright terrain at the top of the mosaic, just left of center, lies a very intriguing feature: a strikingly dark spot from which diffuse dark material appears to extend to the northeast. The origin of this feature is not yet known, but it, too, lies within the radar image; Cassini scientists will thus be able to study it using these complementary observations.

The mosaic is centered on a region at 1 degree north latitude, 21 degree west longitude on Titan. The Cassini spacecraft narrow-angle camera images were taken using a filter sensitive to wavelengths of polarized infrared light and were acquired at distances ranging from approximately 148,300 to 112,800 kilometers (92,100 to 70,100 miles) from Titan. Resolution in the images is about 1 to 2 kilometers (0.6 to 1.2 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

Although the Huygens probe has now pierced the murky skies of Titan and landed on its surface, much of the moon remains for the Cassini spacecraft to explore. Titan continues to present exciting puzzles.

This view of Titan uncovers new territory not previously seen at this resolution by Cassini’s cameras. The view is a composite of four nearly identical wide-angle camera images, all taken using a filter sensitive to wavelengths of infrared light centered at 939 nanometers. The individual images have been combined and contrast-enhanced in such a way as to sharpen surface features and enhance overall brightness variations.

Some of the territory in this view was covered by observations made by the Cassini synthetic aperture radar in October 2004 and February 2005. At large scales, there are similarities between the views taken by the imaging science subsystem cameras and the radar results, but there also are differences.

For example, the center of the floor of the approximately 80-kilometer-wide (50-mile) crater identified by the radar team in February (near the center in this image, see PIA07368 for the radar image) is relatively bright at 2.2 centimeters, the wavelength of the radar experiment, but dark in the near-infrared wavelengths used here by Cassini’s optical cameras. This brightness difference is also apparent for some of the surrounding material and could indicate differences in surface composition or roughness.

Such comparisons, as well as information from observations acquired by the visual and infrared mapping spectrometer at the same time as the optical camera observations, are important in trying to understand the nature of Titan’s surface materials.

The images for this composite view were taken with the Cassini spacecraft on March 31, 2005, at distances ranging from approximately 146,000 to 130,000 kilometers (91,000 to 81,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of about 57 degrees. The image scale is 8 kilometers (5 miles) per pixel. Previous observations indicate that, due to Titan’s thick, hazy atmosphere, the sizes of surface features that can be resolved are a few times larger than the actual pixel scale.

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

Pandora is seen in this dramatic view, orbiting just beyond the outer edge of Saturn’s F ring. Several bright areas are visible within the F ring. In the main rings, the Keeler gap and the Encke gap, with a bright ringlet, are also visible. Pandora is 84 kilometers (52 miles) across.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 18, 2005, at a distance of approximately 1.2 million kilometers (746,000 miles) from Pandora and at a Sun-Pandora-spacecraft, or phase, angle of 108 degrees. The image scale is 7 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

Image credit: NASA/JPL/SSI
Saturn’s moon Mimas shines in reflected ultraviolet light from the Sun in this Cassini image. Ultraviolet images of Saturn’s moons often reveal the walls of their myriad craters in greater contrast than do images taken in visible light. This view, which shows the large impact crater Herschel, is no exception. Mimas is 397 kilometers (247 miles) across.

The image was taken with the Cassini spacecraft narrow-angle camera using a filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers. The image was acquired on Feb. 18, 2005, at a distance of approximately 938,000 kilometers (583,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 99 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 News Release

Saturn’s icy, impact-riddled moon Mimas slips briefly in front of Saturn’s moon Janus in this movie from Cassini. Mimas is 397 kilometers (247 miles) across, while Janus is 181 kilometers (113 miles) across.

The movie was created from 37 original images taken over the course of 20 minutes as the spacecraft’s narrow-angle camera remained pointed toward Janus. Although Mimas moves a greater distance across the field of view, Janus also moved perceptibly during this time. The images were aligned to keep Janus close to the center of the scene. Additional frames were inserted between the 37 Cassini images in order to smooth the appearance of Mimas’ movement — a scheme called interpolation. Close-up images from the few minutes surrounding the occultation are arranged into a strip along the bottom of the movie.

The terrain on Mimas seen here is about 80 degrees west of the terrain seen in a previously released movie (see Mimas on the Move), which showed the little moon appearing to cross Saturn’s ring plane from Cassini’s vantage point. In that previous movie, the rim of the large impact crater Herschel (130 kilometers, or 80 miles wide) was visible as a flattening of the moon’s eastern limb. In the new movie, Herschel is almost at dead center.

Contrast on Janus was mildly enhanced to aid the visibility of its surface. The right side of Mimas appears bright because the moon was partly overexposed in this image sequence.

The images for this movie were taken in visible light on March 5, 2005, when Cassini was approximately 1.8 million kilometers (1.1 million miles) from Mimas and 1.9 million kilometers (1.2 million miles) from Janus. The image scale is approximately 11 kilometers (7 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

As it loops around Saturn, Cassini periodically gets a good view of Saturn’s moon Hyperion. Hyperion chaotically tumbles around in its orbit and is perhaps the largest irregularly-shaped moon in the solar system. New details about this oddball worldlet will certainly come to light in September, 2005, when Cassini is slated to approach Hyperion at a distance of 990 kilometers (615 miles). Hyperion is 266 kilometers (165 miles) across.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera in October 2004 and February 2005, at distances ranging from 1.3 to 1.6 million kilometers (808,000 to 994,000 million miles) from Hyperion and at Sun-Hyperion-spacecraft, or phase, angles ranging from 42 to 66 degrees. Resolution in the original images was 8 to 10 kilometers (5 to 6 miles) per pixel. The images have been contrast-enhanced and magnified by a factor of two to aid visibility.

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

Image credit: NASA/JPL/SSI
The Cassini spacecraft’s two close flybys of Saturn’s icy moon Enceladus have revealed that the moon has a significant atmosphere. Scientists, using Cassini’s magnetometer instrument for their studies, say the source may be volcanism, geysers, or gases escaping from the surface or the interior.

When Cassini had its first encounter with Enceladus on Feb. 17 at an altitude of 1,167 kilometers (725 miles), the magnetometer instrument saw a striking signature in the magnetic field. On March 9, Cassini approached to within 500 kilometers (310 miles) of Enceladus’ surface and obtained additional evidence.

The observations showed a bending of the magnetic field, with the magnetospheric plasma being slowed and deflected by the moon. In addition, magnetic field oscillations were observed. These are caused when electrically charged (or ionized) molecules interact with the magnetic field by spiraling around the field line. This interaction creates characteristic oscillations in the magnetic field at frequencies that can be used to identify the molecule. The observations from the Enceladus flybys are believed to be due to ionized water vapor.

“These new results from Cassini may be the first evidence of gases originating either from the surface or possibly from the interior of Enceladus,” said Dr. Michele Dougherty, principal investigator for the Cassini magnetometer and professor at Imperial College in London. In 1981, NASA’s Voyager spacecraft flew by Enceladus at a distance of 90,000 kilometers (56,000 miles) without detecting an atmosphere. It’s possible detection was beyond Voyager’s capabilities, or something may have changed since that flyby.

This is the first time since Cassini arrived in orbit around Saturn last summer that an atmosphere has been detected around a moon of Saturn, other than its largest moon, Titan. Enceladus is a relatively small moon. The amount of gravity it exerts is not enough to hold an atmosphere very long. Therefore, at Enceladus, a strong continuous source is required to maintain the atmosphere.

The need for such a strong source leads scientists to consider eruptions, such as volcanoes and geysers. If such eruptions are present, Enceladus would join two other such active moons, Io at Jupiter and Triton at Neptune. “Enceladus could be Saturn’s more benign counterpart to Jupiter’s dramatic Io,” said Dr. Fritz Neubauer, co-investigator for the Cassini magnetometer, and a professor at the University of Cologne in Germany.

Since the Voyager flyby, scientists have suspected that this moon is geologically active and is the source of Saturn’s icy E ring. Enceladus is the most reflective object in the solar system, reflecting about 90 percent of the sunlight that hits it. If Enceladus does have ice volcanoes, the high reflectivity of the moon’s surface might result from continuous deposition of icy particles originating from the volcanoes.

Enceladus’ diameter is about 500 kilometers (310 miles), which would fit in the state of Arizona. Yet despite its small size, Enceladus exhibits one of the most interesting surfaces of all the icy satellites.

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 largest and hazy moon, Titan, has a surface shaped largely by Earth-like processes of tectonics, erosion, winds, and perhaps volcanism. The findings are published in this week’s issue of the journal Nature.

Titan, long held to be a frozen analog of early Earth, has liquid methane on its cold surface, unlike the water found on our home planet. Among the new discoveries is what may be a long river, roughly 1,500 kilometers long (930 miles). Scientists have also concluded that winds on Titan blow a lot faster than the moon rotates, a fact long predicted but never confirmed until now.

Tectonism (brittle fracturing and faulting) has clearly played a role in shaping Titan’s surface. “The only known planetary process that creates large-scale linear boundaries is tectonism, in which internal processes cause portions of the crust to fracture and sometimes move either up, down or sideways,” said Dr. Alfred McEwen, Cassini imaging team member from the University of Arizona, Tucson. “Erosion by fluids may accentuate the tectonic fabric by depositing dark materials in low areas and enlarging fractures. This interplay between internal forces and fluid erosion is very Earth-like.”

Cassini images collected during close flybys of the moon show dark, curving and linear patterns in various regions on Titan, but mostly concentrated near the south pole. Some extend up to 1,500 kilometers (930 miles) long. Images from the European Space Agency’s Huygens probe show clear evidence for small channels a few kilometers long, probably cut by liquid methane. Cassini imaging scientists suggest that the dark, curved and linear patterns seen in the Cassini orbiter images of Titan may also be channels, though there is no direct evidence for the presence of fluids. If these features are channels, it would make the ones near the south pole nearly as long as the Snake River, which originates in Wyoming and flows across four states.

Since most of the cloud activity observed on Titan by Cassini has occurred over the south pole, scientists believe this may be where the cycle of methane rain, channel carving, runoff, and evaporation is most active, a hypothesis that could explain the presence of the extensive channel-like features seen in this region. In analyzing clouds of Titan’s lower atmosphere, scientists have concluded that the winds on Titan blow faster than the moon rotates, a phenomenon called super-rotation. In contrast, the jet streams of Earth blow slower than the rotation rate of our planet.

“Models of Titan’s atmosphere have indicated that it should super-rotate just like the atmosphere of Venus, but until now there have been no direct wind measurements to test the prediction,” said Cassini imaging team member Dr. Tony DelGenio of NASA’s Goddard Institute for Space Studies, in New York. DelGenio made the first computer simulation predicting Titan super-rotation a decade ago.

Titan’s winds are measured by watching its clouds move. Clouds are rare on Titan, and those that can be tracked are often too small and faint to be seen from Earth. Ten clouds have been tracked by Cassini, giving wind speeds as high as 34 meters per second (about 75 miles per hour) to the east — hurricane strength — in Titan’s lower atmosphere. “This result is consistent with the predictions of Titan weather models, and it suggests that we now understand the basic features of how meteorology works on slowly rotating planets,” said Del Genio.

“We’ve only just begun exploring the surface of Titan, but what’s struck me the most so far is the variety of the surface patterns that we?bfre seeing. The surface is very complex, and shows evidence for so many different modification processes,” said Dr. Elizabeth Turtle, Cassini imaging team associate in the Lunar and Planetary Laboratory at the University of Arizona, Tucson and co-author of one of the papers in Nature.

“Throughout the solar system, we find examples of solid bodies that show tremendous geologic variation across their surfaces. One hemisphere often can bear little resemblance to the other,” said Dr. Carolyn Porco, Cassini imaging team leader, Space Science Institute, Boulder, Colo. “On Titan, it’s very likely to be this and more.”

These results are based on Cassini orbiter images of Titan collected over the last eight months during a distant flyby of the south pole and three close encounters of Titan’s equatorial region. Cassini cameras have covered 30 percent of Titan’s surface, imaging features as small as 1 to 10 kilometers (0.6 to 6 miles). Cassini is scheduled to make 41 additional close Titan flybys in the next three years.

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