Showing posts with label Cassini Mission to Saturn. Show all posts
Showing posts with label Cassini Mission to Saturn. Show all posts

Friday, July 25, 2008

Impact Craters





This side-by-side view shows a newly discovered impact crater (at left) compared with a previously discovered crater (at right). The new crater was just discovered by the Cassini spacecraft's radar instrument during its most recent Titan flyby on May 12, 2008. This makes the fourth feature definitely identified as an impact crater so far on Titan -- fewer than 100 features are regarded as possible impacts. Compared with Saturn's other moons, which have many thousands of craters, Titan's surface is very sparsely cratered. This is in part due to Titan's dense atmosphere, which burns up the smaller impacting bodies before they can hit the surface. Geological processes, such as wind-driven motion of sand and icy volcanism, may also wipe out craters.

Both images are about 350 kilometers (217 miles) in width. The crater on the right was discovered by Cassini in 2005 and is shown here for comparison. It is 80 kilometers (50 miles) in diameter (see PIA07368), with the radar illumination from above. Called Sinlap, this crater is estimated to be about 1,300 meters (984 feet) deep. The new feature pictured on the left, which has not been named yet, is bigger than the Sinlap crater with a diameter of about 112 kilometers (70 miles).

The new crater is located at about 26 degrees north latitude, 200 degrees west longitude, in the bright region known as Dilmun, about 1,000 kilometers (600 miles) north of the Huygens landing site. In its image, also illuminated from above, it appears slightly irregular, suggesting that it was modified after it was formed, perhaps by collapses of segments of its rim onto the floor. The crater floor appears flat, and two small bright spots indicate a likely central peak complex. The ejecta blanket (surrounding material) from this crater is less prominent than that of the Sinlap crater. The crater's more degraded character suggests it could be older than Sinlap (assuming that erosive processes are the same at both locations, which are at similar latitudes).

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's 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 radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov/home/index.cfm.

Tectonics on Titan





A set of three parallel ridges was seen by the Cassini spacecraft's radar instrument during the latest Titan flyby on May 12, 2008. This combination is unlikely to be a coincidence -- the best explanation for these features is that they are tilted or separated blocks of broken or faulted crust, now exposed as high ridges. Their regular spacing is typical of regions that have been compressed or extended over large areas; as an example, the western United States Basin and Range Province was formed by extension. Such interactions are called tectonics, although they do not happen in the same way as plate tectonics, which is a process unique to Earth.

The ridges, which appear on the left side of the image, are rugged features and are elevated above surrounding terrain. The brightness patterns mean that the materials are fractured or blocky at the radar wavelength (2.17 centimeters, or about 1 inch). Along the south sides of the ridges are prominent cliffs, or scarps, present as thin, radar-dark lines trending west-to-east, and interpreted as faults. These features are dark due to shadowing from the radar illumination, and have heights up to a few hundred meters (several hundred feet), based on preliminary estimates of slopes.

The area shown here is located in the mountainous region called Xanadu. The ridges are similar in many ways to mountain chains seen at similar latitude but about 90 degrees to the west, just west of Shangri-La (observed during a flyby in October 2005, PIA08454). Both regions have mountain chains or ridges that are oriented west-to-east and are spaced about 50 kilometers (30 miles) apart. This indicates tectonic forces have acted in a north to south direction at Titan’s equatorial region and have resulted in regular effects in Titan’s crust, evidence that will help scientists better understand Titan’s crust and interior.

Other linear features, probably related to the formation of the ridges, and circular features, perhaps eroded impact craters now filled with radar-dark (smooth) material, are also seen in the image. The largest circular feature, at bottom center, is about 20 km in diameter.

The image is centered at 2 degrees south, 127 degrees west and was obtained on May 12, 2008, with a resolution of about 300 meters (980 feet). The open arrow indicates the direction of radar illumination. The dashed white line in the upper portion is an artifact of the SAR processing and will be removed in later versions.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's 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 radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov/home/index.cfm.

Saturn's Infrared Temperature Snapshot





Scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years. The pattern ripples back and forth like a wave within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern. The temperature "snapshot" shown in these two images captures two different phases of this wave oscillation: the temperature at Saturn's equator switches from hot to cold, and temperatures on either side of the equator switch from cold to hot every Saturn half-year.

The image on the left was taken in 1997 and shows the temperature at the equator is colder than the temperature at 13 degrees south latitude. Conversely, the image on the right taken in 2006 shows the temperature at the equator is warmer.

Map of Dione - May 2008





This global map of Saturn's moon Dione was created using images taken during Cassini spacecraft flybys, with Voyager images filling in the gaps in Cassini's coverage.

An extensive system of bright ice cliffs created by tectonic fractures adorns the moon's trailing hemisphere.

The map is a simple cylindrical (equidistant) projection and has a scale of 614 meters (2,014 feet) per pixel at the equator. The mean radius of Dione used for projection of this map is 562 kilometers (349 miles). This updated map has been shifted west by 0.6 degrees of longitude, compared to the previously released Cassini product (PIA08341), in order to conform to the International Astronomical Union longitude system convention for Dione.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov .

Hissing Storm




A bright, powerful, lightning-producing storm churns and coasts along the lane of Saturn's southern hemisphere nicknamed "Storm Alley" by scientists.

NASA's Cassini spacecraft detected this particular tempest after nearly two years during which Saturn did not appear to produce any large electrical storms of this kind. The storm appears as a bright, irregular splotch on the planet near lower right.

Lightning flashes within the persistent storm produce radio waves, called Saturn Electrostatic Discharges, which the Cassini radio and plasma wave science instrument first detected on Nov. 27, 2007. Cassini's imaging cameras then spotted the storm, taking the images used to create this color view about a week later on Dec. 6.

This electrical storm is similar in appearance and intensity to those previously monitored by Cassini. All of these powerful electrostatic producing storms appeared at about 35 degrees south latitude on Saturn. (See PIA07788, PIA08142 and PIA06197 for additional images of Saturn's electrical storms imaged by Cassini.)

This storm has now been continuously tracked by Cassini for several months, whereas previous storms observed by the spacecraft lasted for less than 30 days: See PIA08411 for images of the storm acquired three months after this view. The view looks toward the un-illuminated side of the rings from about 5 degrees above the ringplane. Tethys (1,071 kilometers, or 665 miles across) is seen here in the foreground, and casts its shadow onto the high northern latitudes.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired with the Cassini spacecraft wide-angle camera at a distance of approximately 1.7 million kilometers (1 million miles) from Saturn. Image scale is 97 kilometers (60 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 operations center is based at the Space Science Institute in Boulder, Colo. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

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

Unrolling the F-ring





The complex structure of Saturn's quirky F ring is unfurled in this mosaic made up of images taken by NASA's Cassini spacecraft.

The mosaic covers 255 degrees of longitude within the F ring, which represents about 70 percent of the ring's circumference around Saturn. From top to bottom, the mosaic represents an area 1,500 kilometers (930 miles) in radial width.

The 107 images used to create the mosaic were processed to make the ring appear as if it has been straightened, making it easier to see the ring's structure. Here, the vertical axis represents distance from Saturn and the horizontal axis represents longitude around Saturn. This frame of reference is centered on the bright core of the F ring, at the vertical center of the mosaic. In this system, the core is considered to be stationary; objects closer to Saturn (or below vertical center) move toward right, and objects farther from Saturn (here, above the core) move toward left.

Ring scientists now understand a great deal about what causes the various features in the ring. In addition to the powerful perturbing effect of the moon Prometheus (see PIA07750, there is thought to be a population of small objects in the F-ring region that interact with the ring's core to produce the structures seen (see PIA07716). Two of the images had flaws, which caused the vertical lines seen on the right side of the mosaic. There is also a faint, roughly vertical, wavelike pattern in the view, which is an artifact of the process used to straighten the ring's shape.

The clear spectral filter images in this mosaic were obtained with the Cassini spacecraft narrow-angle camera on March 31, 2007, at a distance of about 2 million kilometers (1.2 million miles) from Saturn.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

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



Saturn's Long-lived Storm





It is no Great Red Spot, but these two side-by-side views show the longest-lived electrical storm yet observed on Saturn by NASA's Cassini spacecraft.

The views were acquired more than three months after the storm was first detected from its lightning-produced radio discharges on Nov. 27, 2007. See PIA08410 for an earlier color view of this storm. Cassini imaging scientists believe the storm to be a vertically extended disturbance that penetrates from Saturn's lower to upper troposphere.

The view at left was created by combining images taken using red, green and blue spectral filters, and shows Saturn in colors that approximate what the human eye would see. The storm stands out with greater clarity in the sharpened, enhanced color view at right. This view combines images taken in infrared, green and violet light at 939, 567 and 420 nanometers respectively and represents an expansion of the wavelength region of the electromagnetic spectrum visible to human eyes. This view looks toward the un-illuminated side of the rings from about 3 degrees above the ringplane. Janus (181 kilometers, or 113 miles across) appears as a dark speck just beneath the rings in both images.

These images were obtained with the Cassini spacecraft wide-angle camera on March 4, 2008, at a distance of approximately 1.3 million kilometers (800,000 miles) from Saturn. Image scale is 74 kilometers (46 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 operations center is based at the Space Science Institute in Boulder, Colo. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

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