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A Twisted Tale
Description A Twisted Tale
Full Description Saturn's D ring--the innermost of the planet's rings--sports an intriguing structure that appears to be a wavy, or "vertically corrugated," spiral. This continuously changing ring structure provides circumstantial evidence for a possible recent collision event in the rings. Support for this idea comes from the appearance of a structure in the outer D-ring that looks, upon close examination, like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). When viewed along a line of sight nearly in the ringplane, a pattern of brightness reversals is observed: a part of the ring that appears bright on the far side of the rings appears dark on the near side of the rings, and vice versa (see D Ring Sight Lines). This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material (see image with inset graphic). An observation made with NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its wavelength was then 60 kilometers (37 miles). There were insufficient observations to discern the spiral nature of the feature. Thus, it appears the wavelength of the wavy structure has been decreasing: that is, this feature has been winding up like a spring over time. The rate at which the pattern appears to be winding up is quite close to the rate scientists would expect for a vertically corrugated spiraling sheet of material at this location in the rings that is responding to gravitational forcing from Saturn. As Cassini imaging scientists extrapolated the spiraling trend backward in time, they found that it completely unwound in 1984, leaving only an inclined, or tilted, sheet of material. The researchers speculate such an inclined sheet may have been produced around that time by the impact of a comet or meteoroid into the D ring which kicked out a cloud of fine particles that ultimately inherited some of the tilt of the impactor's trajectory as it slammed into the rings. Another possibility is that the impactor struck an already inclined moonlet, shattered it to bits and the debris remained in an inclined orbit. 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 . Credit: NASA/JPL/Space Science Institute
Date October 11, 2006
A Twisted Tale (with inset g …
Description A Twisted Tale (with inset graphic)
Full Description Saturn's D ring--the innermost of the planet's rings--sports an intriguing structure that appears to be a wavy, or "vertically corrugated," spiral. This continuously changing ring structure provides circumstantial evidence for a possible recent collision event in the rings. Support for this idea comes from the appearance of a structure in the outer D-ring that looks, upon close examination, like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). When viewed along a line of sight nearly in the ringplane, a pattern of brightness reversals is observed: a part of the ring that appears bright on the far side of the rings appears dark on the near side of the rings, and vice versa (see D Ring Sight Lines). This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material. An observation made with NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its wavelength was then 60 kilometers (37 miles). There were insufficient observations to discern the spiral nature of the feature. Thus, it appears the wavelength of the wavy structure has been decreasing: that is, this feature has been winding up like a spring over time. The rate at which the pattern appears to be winding up is quite close to the rate scientists would expect for a vertically corrugated spiraling sheet of material at this location in the rings that is responding to gravitational forcing from Saturn. As Cassini imaging scientists extrapolated the spiraling trend backward in time, they found that it completely unwound in 1984, leaving only an inclined, or tilted, sheet of material. The researchers speculate such an inclined sheet may have been produced around that time by the impact of a comet or meteoroid into the D ring which kicked out a cloud of fine particles that ultimately inherited some of the tilt of the impactor's trajectory as it slammed into the rings. Another possibility is that the impactor struck an already inclined moonlet, shattered it to bits and the debris remained in an inclined orbit. 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 . Credit: NASA/JPL/Space Science Institute
Date October 11, 2006
Tethys and Titan
Description Cassini looks toward Tethys and its great crater Odysseus, while at the same time capturing veiled Titan in the distance (at left).
Full Description Cassini looks toward Tethys and its great crater Odysseus, while at the same time capturing veiled Titan in the distance (at left). Titan (5,150 kilometers, or 3,200 miles across) is shrouded in a thick, smog-like atmosphere in which many small, potential impactors burn up before hitting the moon's surface. Crater-pocked Tethys (1,071 kilometers, or 665 miles across) has no such protective layer, although even a thick blanket of atmosphere would have done little good against the impactor that created Odysseus. The eastern limb of Tethys is overexposed in this view. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 6, 2006, at a distance of approximately 4 million kilometers (2.5 million miles) from Titan and 2.7 million kilometers (1.7 million miles) from Tethys. The image scale is 25 kilometers (16 miles) per pixel on Titan and 16 kilometers (10 miles) per pixel on Tethys. 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 . *Credit:* NASA/JPL/Space Science Institute
Date February 17, 2006
Deep Impact Launch
title Deep Impact Launch
date 01.12.2005
description Erupting from the flames and smoke beneath it, NASA's Deep Impact spacecraft lifts off at 1:47 p.m. EST today from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla. A NASA Discovery mission, Deep Impact is heading for space and a rendezvous 83 million miles from Earth with Comet Tempel 1. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface July 4, 2005, Deep Impact's flyby spacecraft will reveal the secrets of the comet's interior by collecting pictures and data of how the crater forms, measuring the crater's depth and diameter as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. It will send the data back to Earth through the antennas of the Deep Space Network. *Image Credit*: NASA
Deep Impact
title Deep Impact
description This is an artist's rendition of the flyby spacecraft releasing the impactor, 24 hours before the impact event. Pictured from left to right are comet Tempel 1, the impactor, and the flyby spacecraft. The impactor is a 370-kilogram mass with an onboard guidance system. The flyby spacecraft includes a solar panel (right), a high-gain antenna (top), a debris shield (left, background), and science instruments for high and medium resolution imaging, infrared spectroscopy, and optical navigation (yellow box and cylinder, lower left). The fly spacecraft is about 3.2 meters long, 1.7 meters wide, and 2.3 meters high. The launch payload has a mass of 1020 kilograms. *Image Credit*: NASA
Ganymede's Khensu Crater
title Ganymede's Khensu Crater
date 09.06.1996
description The dark-floored crater Khensu is the target of this image of Ganymede. The Solid-State Imaging System onboard the Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the jovian system. Khensu is located at 20N latitude and 1530W longitude in a region of bright terrain known as Uruk Sulcus, and is about 13 kilometers in diameter. Like some other craters on Ganymede, it possesses an unusually dark floor and a bright ejecta blanket. The dark component may be residual material from the impactor that formed the crater. Another possibility is that the impactor may have punched through the bright surface to reveal a dark layer beneath. Another large crater named El is partly visible in the top righthand corner of the image. This crater is 54 kilometers in diameter and has a small "pit" in its center. Craters with such a "central pit" are common across Ganymede and are especially intriguing since they may reveal secrets about the structure of the satellite's shallow subsurface. North is to the upper left of the picture, and the Sun illuminates the surface from nearly overhead. The image covers an area about 100 by 86 kilometers across at a resolution of 111 meters per picture element. The image was taken on September 6, 1996, by the Solid-State Imaging System onboard the Galileo spacecraft. *Image Credit*: Brown University
Deep Impact Spacecraft Colli …
Name of Image Deep Impact Spacecraft Collides With Comet Tempel 1 (Video)
Date of Image 2005-07-04
Full Description After 172 days and 268 million miles of deep space travel, the NASA Deep Impact spacecraft successfully reached out and touched comet Tempel 1. The collision between the coffee table-sized space probe and city-sized comet occurred July 4, 2005 at 12:52 a.m. CDT. Comprised of images taken by the targeting sensor aboard the impactor probe, this movie shows the spacecraft approaching the comet up to just seconds before impact. Mission scientists expect Deep Impact to provide answers to basic questions about the formation of the solar system. Principal investigator for Deep Impact, Dr. Michael A?Hearn of the University of Maryland in College Park, is responsible for the mission, and project management is handled by the Jet Propulsion Laboratory in Pasadena, California. The program office at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama assisted the Science Mission Directorate at NASA Headquarters in Washington with program management, technology planning, systems assessment, flight assurance and public outreach. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation of Boulder, Colorado. (NASA/JPL-Caltech/UMD)
Europa, Ganymede, and Callis …
PIA01656
Jupiter
Solid-State Imaging
Title Europa, Ganymede, and Callisto: Surface comparison at high spatial resolution
Original Caption Released with Image Ganymede's youngest large craters would have been created only about one billion years ago. Europa's surface in this model should be very young, with this satellite being geologically quite active even today. The images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. They were processed by the Institute of Planetary Exploration of the German Aerospace Center (DLR) in Berlin, Germany, and scaled to a size of 150 meters per pixel (m/pixel). North is up in all images. The spatial resolution of the original data was 180 m/pixel for Europa and Ganymede and 90 m/pixel for Callisto. The Europa image was taken during Galileo's 6th orbit, the Ganymede image during the 7th, and the Callisto image during the 10th orbit. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ]., These images show a comparison of the surfaces of the three icy Galilean satellites, Europa, Ganymede, and Callisto, scaled to a common resolution of 150 meters per picture element (pixel). Despite the similar distance of 0.8 billion kilometers to the sun, their surfaces show dramatic differences. Callisto (with a diameter of 4817 kilometers) is "peppered" by impact craters, but is also covered by a dark material layer of so far unknown origin, as seen here in the region of the Asgard multi-ring basin. It appears that this layer erodes or covers small craters. Ganymede's landscape is also widely formed by impacts, but different from Callisto, much tectonic deformation can be observed in the Galileo images, such as these of Nicholson Regio. Ganymede, with a diameter of 5268 kilometers (one-and-a-half times larger than the Earth's moon), is the largest moon in the solar system. Contrary to Ganymede and Callisto, Europa (diameter 3121 kilometers) has a sparsely cratered surface, indicating that geologic activity took place more recently. Globally, ridged plains and the so-called "mottled terrain" are the main landforms. In the high-resolution image presented here showing the area around the Agave and Asterius dark lineaments, older ridges dominate the surface, while a small part of the younger mottled terrain is visible to the lower left of the image center. While all three moons are believed to be nearly as old as the solar system (4.5 billion years), the age of the surfaces, i.e. the time since the last major geologic activity took place, is still subject to debate. Without having surface samples in hand, the only method to roughly determine a planet's or satellite's geologic surface age is by crater counting. However, assumptions about the impactor fluxes must be made based on theoretical models and possible observations of candidate impactors such as asteroids and comets. Asteroids should have been very common in the early days of the solar system, but this source should have been largely exhausted by about 3.8 billion years before present. For comets, the impactor flux is believed to be rather constant throughout the whole lifetime of the solar system, meaning that the probability of an impact of a large comet is similar today as it was, say, four billion years ago. Assuming the asteroids have been the dominant bodies that impacted the Galilean satellites (which is believed to be the case on the Moon, the Earth, and other inner solar system bodies as well as within the asteroid belt itself), the surfaces of Ganymede and Callisto must be old, roughly four billion years. In this case, the Europan surface would by comparison have a mean age of one-hundred to several-hundred million years. Low-level geologic activity on Europa might be possible, but Ganymede and Callisto should be geologically dead. Assuming on the other hand that comets have been the main impactors in the Jovian system, Callisto's surface would still be determined to be old, but
Moderate-resolution view of …
PIA00898
Jupiter
Solid-State Imaging
Title Moderate-resolution view of Callisto's surface
Original Caption Released with Image This five-frame mosaic of the Jovian satellite Callisto shows a surface densely populated with impact craters. However, close inspection of this image reveals differences among the craters. For example, a few of the craters contain central dome-shaped features, while others contain depressions, or pits, within the crater floor. Scientists study differences among craters such as these to learn more about both the surface that was struck by an impactor, and the impactor itself. These images were obtained by the Galileo spacecraft on its eighth orbit around Jupiter at a distance of 48,000 km from Callisto. The mosaic is centered at 31 S. latitude and 122 W. longitude, and covers an area approximately 700 kilometers (420 miles) by 900 kilometers (540 miles)-- somewhat larger than Montana. The finest details that can be discerned in this picture are about 1.8 kilometers across (0.93 km/pixel). The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo
Tethys and Titan
PIA07705
Saturn
Imaging Science Subsystem - …
Title Tethys and Titan
Original Caption Released with Image Cassini looks toward Tethys and its great crater Odysseus, while at the same time capturing veiled Titan in the distance (at left). Titan (5,150 kilometers, or 3,200 miles across) is shrouded in a thick, smog-like atmosphere in which many small, potential impactors burn up before hitting the moon's surface. Crater-pocked Tethys (1,071 kilometers, or 665 miles across) has no such protective layer, although even a thick blanket of atmosphere would have done little good against the impactor that created Odysseus. The eastern limb of Tethys is overexposed in this view. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 6, 2006, at a distance of approximately 4 million kilometers (2.5 million miles) from Titan and 2.7 million kilometers (1.7 million miles) from Tethys. The image scale is 25 kilometers (16 miles) per pixel on Titan and 16 kilometers (10 miles) per pixel on Tethys. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]. The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ].
Kittu Dark Ray Crater
PIA01611
Jupiter
Solid-State Imaging
Title Kittu Dark Ray Crater
Original Caption Released with Image View of the dark ray crater Kittu on Jupiter's moon, Ganymede. Kittu is seen in approximately true color, as imaged with the Galileo camera's violet, one micrometer, and near infrared filters. The crater shows a bright white central peak and rim, and dark brownish material surrounding it. Diffuse dark rays, sprinkled thinly atop surrounding grooved terrain, emanate from the impact site. The dark material dusted over the surface is probably part of a dark impactor (asteroid or comet) which was strewn across the surface upon impact. The impactor hit grooved terrain, and a straight segment of the crater's rim was created when a portion of the rim collapsed along the trend of an older fault. North is to the bottom of the picture and the sun illuminates the surface from the left. The mosaic, centered at 0 degrees latitude and 335 degrees longitude, covers an area approximately 70 by 100 kilometers. The resolution in the color portion of this image is about 280 meters per picture element, while the resolution in the black and white portion is 145 meters per picture element. The images were taken beginning on April 5, 1997 from 6 hours, 39 minutes, 46 seconds Universal Time at a range of 14252 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo [ http://galileo.jpl.nasa.gov/galileo/sepo ]
Craters on South Polar Layer …
PIA09670
Sol (our sun)
HiRISE
Title Craters on South Polar Layered Deposits
Original Caption Released with Image Click on image for larger version This subimage, about 2.5 km across, shows the south polar layered deposits exposed in a scarp illuminated from the lower right. This HiRISE image (PSP_002882_0940 [ http://hirise.lpl.arizona.edu/PSP_002882_0940 ]) was taken in the southern spring, when the surface was completely covered by carbon dioxide frost. Therefore, most of the brightness variations in this scene are caused by topography. The polar layered deposits are broken into blocks by fractures in two directions. Neither set of fractures is parallel to the current scarp face, suggesting that they were not formed as the scarp was eroded, but instead are due to pre-existing weaknesses in the polar layered deposits. The four craters at lower left appear to have formed at the same time by an impactor that broke up as it entered the Martian atmosphere. The presence of many craters such as these on the south polar layered deposits indicates that they are not as young as the north polar layered deposits, which have very few craters on them. Observation Toolbox Acquisition date: 3 March 2007 Local Mars time: 7:06 PM Degrees latitude (centered): -85.9° Degrees longitude (East): 303.4° Range to target site: 246.9 km (154.3 miles) Original image scale range: 24.7 cm/pixel (with 1 x 1 binning) so objects ~74 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: POLAR STEREOGRAPHIC Emission angle: 6.7° Phase angle: 78.5° Solar incidence angle: 84°, with the Sun about 6° above the horizon Solar longitude: 196.9°, Northern Autumn NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
Craters on South Polar Layer …
PIA09670
Sol (our sun)
HiRISE
Title Craters on South Polar Layered Deposits
Original Caption Released with Image Click on image for larger version This subimage, about 2.5 km across, shows the south polar layered deposits exposed in a scarp illuminated from the lower right. This HiRISE image (PSP_002882_0940 [ http://hirise.lpl.arizona.edu/PSP_002882_0940 ]) was taken in the southern spring, when the surface was completely covered by carbon dioxide frost. Therefore, most of the brightness variations in this scene are caused by topography. The polar layered deposits are broken into blocks by fractures in two directions. Neither set of fractures is parallel to the current scarp face, suggesting that they were not formed as the scarp was eroded, but instead are due to pre-existing weaknesses in the polar layered deposits. The four craters at lower left appear to have formed at the same time by an impactor that broke up as it entered the Martian atmosphere. The presence of many craters such as these on the south polar layered deposits indicates that they are not as young as the north polar layered deposits, which have very few craters on them. Observation Toolbox Acquisition date: 3 March 2007 Local Mars time: 7:06 PM Degrees latitude (centered): -85.9° Degrees longitude (East): 303.4° Range to target site: 246.9 km (154.3 miles) Original image scale range: 24.7 cm/pixel (with 1 x 1 binning) so objects ~74 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: POLAR STEREOGRAPHIC Emission angle: 6.7° Phase angle: 78.5° Solar incidence angle: 84°, with the Sun about 6° above the horizon Solar longitude: 196.9°, Northern Autumn NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
Craters on South Polar Layer …
PIA09670
Sol (our sun)
HiRISE
Title Craters on South Polar Layered Deposits
Original Caption Released with Image Click on image for larger version This subimage, about 2.5 km across, shows the south polar layered deposits exposed in a scarp illuminated from the lower right. This HiRISE image (PSP_002882_0940 [ http://hirise.lpl.arizona.edu/PSP_002882_0940 ]) was taken in the southern spring, when the surface was completely covered by carbon dioxide frost. Therefore, most of the brightness variations in this scene are caused by topography. The polar layered deposits are broken into blocks by fractures in two directions. Neither set of fractures is parallel to the current scarp face, suggesting that they were not formed as the scarp was eroded, but instead are due to pre-existing weaknesses in the polar layered deposits. The four craters at lower left appear to have formed at the same time by an impactor that broke up as it entered the Martian atmosphere. The presence of many craters such as these on the south polar layered deposits indicates that they are not as young as the north polar layered deposits, which have very few craters on them. Observation Toolbox Acquisition date: 3 March 2007 Local Mars time: 7:06 PM Degrees latitude (centered): -85.9° Degrees longitude (East): 303.4° Range to target site: 246.9 km (154.3 miles) Original image scale range: 24.7 cm/pixel (with 1 x 1 binning) so objects ~74 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: POLAR STEREOGRAPHIC Emission angle: 6.7° Phase angle: 78.5° Solar incidence angle: 84°, with the Sun about 6° above the horizon Solar longitude: 196.9°, Northern Autumn NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
Large Impact Structures on E …
PIA01661
Jupiter
Solid-State Imaging
Title Large Impact Structures on Europa
Original Caption Released with Image The picture compares four large impact structures on Jupiter's icy moon, Europa. Clockwise, from top left, are Pwyll, Cilix, Tyre, and Mannann'an. Impact structures with diameters of more than 20 kilometers are rather rare on Europa. Tyre is most unusual. While the effective crater, which is somewhat larger than the prominent large bull's eye feature, is about 40 kilometers (25 miles) across, the entire structure is much larger. The concentric rings display relatively little relief. Some of the smaller craters near Tyre were formed by material ejected by and then redeposited from the impact which formed Tyre. One hypothesis for such characteristics is that the impactor which formed Tyre penetrated through an icy crust into a less brittle layer. While Pwyll, Cilix, and Mannann'an also display shallow crater depths for their size, they more closely resemble similar sized craters on two neighboring moons of Jupiter, Ganymede and Callisto. Perhaps the impactor did not punch through the upper crust during these events. This might have been the case if the impacting body was smaller or weaker than in the case of Tyre or if the crust was thinner at the location of Tyre during the impact event. North is to the top of the picture. The sun illuminates the surfaces from the right, except for Tyre, where the sun illuminates the surface from the left. The horizontal and vertical grey lines in the Tyre mosaic indicate gaps in the data received for this image. The Pwyll image was taken on December 16, 1997, Cilix on May 31, 1998,Tyre on March 29, 1998, and Mannann'an on March 29, 1998. All images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at URLhttp://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ]
A Twisted Tale
PIA08325
Saturn
Imaging Science Subsystem - …
Title A Twisted Tale
Original Caption Released with Image . The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ]., Figure 1 Saturn's D ring--the innermost of the planet's rings -- sports an intriguing structure that appears to be a wavy, or "vertically corrugated," spiral. This continuously changing ring structure provides circumstantial evidence for a possible recent collision event in the rings. Support for this idea comes from the appearance of a structure in the outer D-ring that looks, upon close examination, like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). When viewed along a line of sight nearly in the ringplane, a pattern of brightness reversals is observed: a part of the ring that appears bright on the far side of the rings appears dark on the near side of the rings, and vice versa (see PIA08326 [ http://photojournal.jpl.nasa.gov/catalog/PIA08326 ]). This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material (see figure 1). An observation made with NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its wavelength was then 60 kilometers (37 miles). There were insufficient observations to discern the spiral nature of the feature. Thus, it appears the wavelength of the wavy structure has been decreasing: that is, this feature has been winding up like a spring over time. The rate at which the pattern appears to be winding up is quite close to the rate scientists would expect for a vertically corrugated spiraling sheet of material at this location in the rings that is responding to gravitational forcing from Saturn. As Cassini imaging scientists extrapolated the spiraling trend backward in time, they found that it completely unwound in 1984, leaving only an inclined, or tilted, sheet of material. The researchers speculate such an inclined sheet may have been produced around that time by the impact of a comet or meteoroid into the D ring which kicked out a cloud of fine particles that ultimately inherited some of the tilt of the impactor's trajectory as it slammed into the rings. Another possibility is that the impactor struck an already inclined moonlet, shattered it to bits and the debris remained in an inclined orbit. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]
A Twisted Tale
PIA08325
Saturn
Imaging Science Subsystem - …
Title A Twisted Tale
Original Caption Released with Image . The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ]., Figure 1 Saturn's D ring--the innermost of the planet's rings -- sports an intriguing structure that appears to be a wavy, or "vertically corrugated," spiral. This continuously changing ring structure provides circumstantial evidence for a possible recent collision event in the rings. Support for this idea comes from the appearance of a structure in the outer D-ring that looks, upon close examination, like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). When viewed along a line of sight nearly in the ringplane, a pattern of brightness reversals is observed: a part of the ring that appears bright on the far side of the rings appears dark on the near side of the rings, and vice versa (see PIA08326 [ http://photojournal.jpl.nasa.gov/catalog/PIA08326 ]). This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material (see figure 1). An observation made with NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its wavelength was then 60 kilometers (37 miles). There were insufficient observations to discern the spiral nature of the feature. Thus, it appears the wavelength of the wavy structure has been decreasing: that is, this feature has been winding up like a spring over time. The rate at which the pattern appears to be winding up is quite close to the rate scientists would expect for a vertically corrugated spiraling sheet of material at this location in the rings that is responding to gravitational forcing from Saturn. As Cassini imaging scientists extrapolated the spiraling trend backward in time, they found that it completely unwound in 1984, leaving only an inclined, or tilted, sheet of material. The researchers speculate such an inclined sheet may have been produced around that time by the impact of a comet or meteoroid into the D ring which kicked out a cloud of fine particles that ultimately inherited some of the tilt of the impactor's trajectory as it slammed into the rings. Another possibility is that the impactor struck an already inclined moonlet, shattered it to bits and the debris remained in an inclined orbit. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]
Asymmetric Crater
PIA04945
Sol (our sun)
Thermal Emission Imaging Sys …
Title Asymmetric Crater
Original Caption Released with Image Released 18 December 2003 Asymmetric craters such as the one in the center of this image are fairly rare. The more typical symmetric craters are formed when meteors impact a surface over a wide range of angles. Only very low impact angles (within 15° of horizontal) result in asymmetric structures such as this one. The bilateral symmetry of the ejecta, like two wings on either side of the elliptical crater, is typical of oblique impacts. The small crater downrange from the main crater could have been caused by the impactor breaking apart before impact or possibly a 'decapitation' of the impactor as it hit with the 'head' traveling farther to form the smaller structure. Image information: VIS instrument. Latitude -8.5, Longitude 227.5 East (132.5 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
Asymmetric Crater
PIA04945
Sol (our sun)
Thermal Emission Imaging Sys …
Title Asymmetric Crater
Original Caption Released with Image Released 18 December 2003 Asymmetric craters such as the one in the center of this image are fairly rare. The more typical symmetric craters are formed when meteors impact a surface over a wide range of angles. Only very low impact angles (within 15° of horizontal) result in asymmetric structures such as this one. The bilateral symmetry of the ejecta, like two wings on either side of the elliptical crater, is typical of oblique impacts. The small crater downrange from the main crater could have been caused by the impactor breaking apart before impact or possibly a 'decapitation' of the impactor as it hit with the 'head' traveling farther to form the smaller structure. Image information: VIS instrument. Latitude -8.5, Longitude 227.5 East (132.5 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
Khensu Crater on Ganymede
PIA01090
Jupiter
Solid-State Imaging
Title Khensu Crater on Ganymede
Original Caption Released with Image The dark-floored crater, Khensu, is the target of this image of Ganymede. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. Khensu is located at 2 degrees latitude and 153 degrees longitude in a region of bright terrain known as Uruk Sulcus, and is about 13 kilometers (8 miles) in diameter. Like some other craters on Ganymede, it possesses an unusually dark floor and a bright ejecta blanket. The dark component may be residual material from the impactor that formed the crater. Another possibility is that the impactor may have punched through the bright surface to reveal a dark layer beneath. Another large crater named El is partly visible in the top-right corner of the image. This crater is 54 kilometers (34 miles) in diameter and has a small "pit" in its center. Craters with such a "central pit" are common across Ganymede and are especially intriguing since they may reveal secrets about the structure of the satellite's shallow subsurface. North is to the top-left of the picture and the sun illuminates the surface from nearly overhead. The image covers an area about 100 kilometers (62 miles) by 86 kilometers (54 miles) across at a resolution of 111 meters (370 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech). This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.
New Craters
PIA09020
Sol (our sun)
Mars Orbiter Camera
Title New Craters
Original Caption Released with Image Office of Space Science, Washington, by NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft. Malin Space Science Systems, San Diego, Calif., built and operates the Mars Orbiter Camera. For more information about images from the Mars Orbiter Camera, see http://www.msss.com/mgs/moc/index.html [ http://www.msss.com/mgs/moc/index.html ]., The Mars Global Surveyor's Mars Orbiter Camera has found that meteorites are hitting the Martian surface and forming new craters all the time. If you were living on Mars, chances are that within 10 or 20 years, an impact would occur close enough to where you live that you'd notice it -- perhaps you'd hear the impact and it would startle you out of your seat. A year ago, it had not occurred to the camera team that they could find places on Mars where meteorites had impacted the surface during the course of the mission. Such craters, if they were forming at all, would be a few meters to a few tens of meters across, much too small to notice (or so they thought) in the wide-angle camera coverage. But, on Jan. 9, 2006, they began to realize that not only could we find such craters, we might also be able to characterize the present-day impact cratering rate on Mars. Surveying for fresh craters formed during the mission would provide the first direct observation -- for any body in the solar system, including Earth and its Moon -- of the present-day cratering rate. This in turn can help test models used all the time by members of the scientific community to estimate the age of features on planetary surfaces. The first fresh impact site, shown on this page, was first noticed on Jan. 9, 2006, in an image acquired three days earlier. The image was acquired by the wide-angle camera at its highest possible spatial resolution, about 240 meters (262 yards) per pixel. To the northwest of the area imaged by the narrow-angle camera, the red, wide-angle context frame showed a dark spot. This spot was not present in any previous image acquired by any spacecraft, from Mariner 9 (which arrived in 1971) on down through Mars Express (which arrived in 2003). Figure A: The first figure shows two red, wide-angle camera context images. The first was taken on June 9, 2001, several years before the impact occurred. The second is the "discovery" image, acquired on January 6, 2006. In both cases, a white box indicates the location of the Mars Orbiter Camera narrow-angle image for which the context image was obtained. For scale, the white boxes are 3 kilometers (1.9 miles) wide. Figure B: In this image, North is up in this map-projected view. The single, broad dark streak that emanates from the impact site and points toward the southwest (lower left) may indicate either the direction that the meteor came from, or its opposite. If it represents the direction that the impactor came from, then the streak results from disruption of dust on the Martian surface as the object came in. If the opposite, then it represents the direction that material was blasted from the impact site, away from the direction that the meteor came. In either case, the impactor came in at a somewhat oblique angle, and broke up just before hitting the ground, because it formed multiple small craters. The 300-meter scale bar represents 328 yards. The Mars Global Surveyor mission is managed for NASA's
New Craters
PIA09020
Sol (our sun)
Mars Orbiter Camera
Title New Craters
Original Caption Released with Image Office of Space Science, Washington, by NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft. Malin Space Science Systems, San Diego, Calif., built and operates the Mars Orbiter Camera. For more information about images from the Mars Orbiter Camera, see http://www.msss.com/mgs/moc/index.html [ http://www.msss.com/mgs/moc/index.html ]., The Mars Global Surveyor's Mars Orbiter Camera has found that meteorites are hitting the Martian surface and forming new craters all the time. If you were living on Mars, chances are that within 10 or 20 years, an impact would occur close enough to where you live that you'd notice it -- perhaps you'd hear the impact and it would startle you out of your seat. A year ago, it had not occurred to the camera team that they could find places on Mars where meteorites had impacted the surface during the course of the mission. Such craters, if they were forming at all, would be a few meters to a few tens of meters across, much too small to notice (or so they thought) in the wide-angle camera coverage. But, on Jan. 9, 2006, they began to realize that not only could we find such craters, we might also be able to characterize the present-day impact cratering rate on Mars. Surveying for fresh craters formed during the mission would provide the first direct observation -- for any body in the solar system, including Earth and its Moon -- of the present-day cratering rate. This in turn can help test models used all the time by members of the scientific community to estimate the age of features on planetary surfaces. The first fresh impact site, shown on this page, was first noticed on Jan. 9, 2006, in an image acquired three days earlier. The image was acquired by the wide-angle camera at its highest possible spatial resolution, about 240 meters (262 yards) per pixel. To the northwest of the area imaged by the narrow-angle camera, the red, wide-angle context frame showed a dark spot. This spot was not present in any previous image acquired by any spacecraft, from Mariner 9 (which arrived in 1971) on down through Mars Express (which arrived in 2003). Figure A: The first figure shows two red, wide-angle camera context images. The first was taken on June 9, 2001, several years before the impact occurred. The second is the "discovery" image, acquired on January 6, 2006. In both cases, a white box indicates the location of the Mars Orbiter Camera narrow-angle image for which the context image was obtained. For scale, the white boxes are 3 kilometers (1.9 miles) wide. Figure B: In this image, North is up in this map-projected view. The single, broad dark streak that emanates from the impact site and points toward the southwest (lower left) may indicate either the direction that the meteor came from, or its opposite. If it represents the direction that the impactor came from, then the streak results from disruption of dust on the Martian surface as the object came in. If the opposite, then it represents the direction that material was blasted from the impact site, away from the direction that the meteor came. In either case, the impactor came in at a somewhat oblique angle, and broke up just before hitting the ground, because it formed multiple small craters. The 300-meter scale bar represents 328 yards. The Mars Global Surveyor mission is managed for NASA's
New Craters
PIA09020
Sol (our sun)
Mars Orbiter Camera
Title New Craters
Original Caption Released with Image Office of Space Science, Washington, by NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft. Malin Space Science Systems, San Diego, Calif., built and operates the Mars Orbiter Camera. For more information about images from the Mars Orbiter Camera, see http://www.msss.com/mgs/moc/index.html [ http://www.msss.com/mgs/moc/index.html ]., The Mars Global Surveyor's Mars Orbiter Camera has found that meteorites are hitting the Martian surface and forming new craters all the time. If you were living on Mars, chances are that within 10 or 20 years, an impact would occur close enough to where you live that you'd notice it -- perhaps you'd hear the impact and it would startle you out of your seat. A year ago, it had not occurred to the camera team that they could find places on Mars where meteorites had impacted the surface during the course of the mission. Such craters, if they were forming at all, would be a few meters to a few tens of meters across, much too small to notice (or so they thought) in the wide-angle camera coverage. But, on Jan. 9, 2006, they began to realize that not only could we find such craters, we might also be able to characterize the present-day impact cratering rate on Mars. Surveying for fresh craters formed during the mission would provide the first direct observation -- for any body in the solar system, including Earth and its Moon -- of the present-day cratering rate. This in turn can help test models used all the time by members of the scientific community to estimate the age of features on planetary surfaces. The first fresh impact site, shown on this page, was first noticed on Jan. 9, 2006, in an image acquired three days earlier. The image was acquired by the wide-angle camera at its highest possible spatial resolution, about 240 meters (262 yards) per pixel. To the northwest of the area imaged by the narrow-angle camera, the red, wide-angle context frame showed a dark spot. This spot was not present in any previous image acquired by any spacecraft, from Mariner 9 (which arrived in 1971) on down through Mars Express (which arrived in 2003). Figure A: The first figure shows two red, wide-angle camera context images. The first was taken on June 9, 2001, several years before the impact occurred. The second is the "discovery" image, acquired on January 6, 2006. In both cases, a white box indicates the location of the Mars Orbiter Camera narrow-angle image for which the context image was obtained. For scale, the white boxes are 3 kilometers (1.9 miles) wide. Figure B: In this image, North is up in this map-projected view. The single, broad dark streak that emanates from the impact site and points toward the southwest (lower left) may indicate either the direction that the meteor came from, or its opposite. If it represents the direction that the impactor came from, then the streak results from disruption of dust on the Martian surface as the object came in. If the opposite, then it represents the direction that material was blasted from the impact site, away from the direction that the meteor came. In either case, the impactor came in at a somewhat oblique angle, and broke up just before hitting the ground, because it formed multiple small craters. The 300-meter scale bar represents 328 yards. The Mars Global Surveyor mission is managed for NASA's
New Craters
PIA09020
Sol (our sun)
Mars Orbiter Camera
Title New Craters
Original Caption Released with Image Office of Space Science, Washington, by NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft. Malin Space Science Systems, San Diego, Calif., built and operates the Mars Orbiter Camera. For more information about images from the Mars Orbiter Camera, see http://www.msss.com/mgs/moc/index.html [ http://www.msss.com/mgs/moc/index.html ]., The Mars Global Surveyor's Mars Orbiter Camera has found that meteorites are hitting the Martian surface and forming new craters all the time. If you were living on Mars, chances are that within 10 or 20 years, an impact would occur close enough to where you live that you'd notice it -- perhaps you'd hear the impact and it would startle you out of your seat. A year ago, it had not occurred to the camera team that they could find places on Mars where meteorites had impacted the surface during the course of the mission. Such craters, if they were forming at all, would be a few meters to a few tens of meters across, much too small to notice (or so they thought) in the wide-angle camera coverage. But, on Jan. 9, 2006, they began to realize that not only could we find such craters, we might also be able to characterize the present-day impact cratering rate on Mars. Surveying for fresh craters formed during the mission would provide the first direct observation -- for any body in the solar system, including Earth and its Moon -- of the present-day cratering rate. This in turn can help test models used all the time by members of the scientific community to estimate the age of features on planetary surfaces. The first fresh impact site, shown on this page, was first noticed on Jan. 9, 2006, in an image acquired three days earlier. The image was acquired by the wide-angle camera at its highest possible spatial resolution, about 240 meters (262 yards) per pixel. To the northwest of the area imaged by the narrow-angle camera, the red, wide-angle context frame showed a dark spot. This spot was not present in any previous image acquired by any spacecraft, from Mariner 9 (which arrived in 1971) on down through Mars Express (which arrived in 2003). Figure A: The first figure shows two red, wide-angle camera context images. The first was taken on June 9, 2001, several years before the impact occurred. The second is the "discovery" image, acquired on January 6, 2006. In both cases, a white box indicates the location of the Mars Orbiter Camera narrow-angle image for which the context image was obtained. For scale, the white boxes are 3 kilometers (1.9 miles) wide. Figure B: In this image, North is up in this map-projected view. The single, broad dark streak that emanates from the impact site and points toward the southwest (lower left) may indicate either the direction that the meteor came from, or its opposite. If it represents the direction that the impactor came from, then the streak results from disruption of dust on the Martian surface as the object came in. If the opposite, then it represents the direction that material was blasted from the impact site, away from the direction that the meteor came. In either case, the impactor came in at a somewhat oblique angle, and broke up just before hitting the ground, because it formed multiple small craters. The 300-meter scale bar represents 328 yards. The Mars Global Surveyor mission is managed for NASA's
A Field of Secondary Craters
PIA09584
Sol (our sun)
HiRISE
Title A Field of Secondary Craters
Original Caption Released with Image Click on image for larger version This HiRISE image (PSP_002281_2115 [ http://hirise.lpl.arizona.edu/PSP_002281_2115 ]) shows a secondary crater field. Secondary craters form when material ejected from a larger impact event impacts the Martian surface. One impact event, depending on the size of the impactor, can form hundreds of millions of secondary craters at essentially the same time. Primary craters (those created directly from an impactor from space) can be the same size as secondary craters, which makes dating surfaces based on the number of accumulated craters difficult to near-impossible. Secondary craters are distinguished from primaries based on their morphologies. They are sometimes irregularly shaped, as seen in this image, because they form at relatively low velocities. The velocity of the impactor determines a crater's size, shape, and depth, with lower energy impacts forming shallow, less-developed craters and higher energy impacts forming deeper, more regular craters. Secondary craters often occur in clusters, as seen here, as a piece of ejecta breaks up before hitting the surface. Primary craters form at random locations globally. Secondary clusters are more likely to be found in groups because of their formation mechanism. Observation Geometry Acquisition date: 1 January 2007 Local Mars time: 3:34 PM Degrees latitude (centered): 31.1 ° Degrees longitude (East): 89.7 ° Range to target site: 291.1 km (181.9 miles) Original image scale range: 29.1 cm/pixel (with 1 x 1 binning) so objects ~87 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: EQUIRECTANGULAR Emission angle: 0.2 ° Phase angle: 57.1 ° Solar incidence angle: 57 °, with the Sun about 33 ° above the horizon Solar longitude: 170.2 °, Northern Summer NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
A Field of Secondary Craters
PIA09584
Sol (our sun)
HiRISE
Title A Field of Secondary Craters
Original Caption Released with Image Click on image for larger version This HiRISE image (PSP_002281_2115 [ http://hirise.lpl.arizona.edu/PSP_002281_2115 ]) shows a secondary crater field. Secondary craters form when material ejected from a larger impact event impacts the Martian surface. One impact event, depending on the size of the impactor, can form hundreds of millions of secondary craters at essentially the same time. Primary craters (those created directly from an impactor from space) can be the same size as secondary craters, which makes dating surfaces based on the number of accumulated craters difficult to near-impossible. Secondary craters are distinguished from primaries based on their morphologies. They are sometimes irregularly shaped, as seen in this image, because they form at relatively low velocities. The velocity of the impactor determines a crater's size, shape, and depth, with lower energy impacts forming shallow, less-developed craters and higher energy impacts forming deeper, more regular craters. Secondary craters often occur in clusters, as seen here, as a piece of ejecta breaks up before hitting the surface. Primary craters form at random locations globally. Secondary clusters are more likely to be found in groups because of their formation mechanism. Observation Geometry Acquisition date: 1 January 2007 Local Mars time: 3:34 PM Degrees latitude (centered): 31.1 ° Degrees longitude (East): 89.7 ° Range to target site: 291.1 km (181.9 miles) Original image scale range: 29.1 cm/pixel (with 1 x 1 binning) so objects ~87 cm across are resolved Map-projected scale: 25 cm/pixel and north is up Map-projection: EQUIRECTANGULAR Emission angle: 0.2 ° Phase angle: 57.1 ° Solar incidence angle: 57 °, with the Sun about 33 ° above the horizon Solar longitude: 170.2 °, Northern Summer NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
Crater Variety
PIA02298
Sol (our sun)
Thermal Emission Imaging Sys …
Title Crater Variety
Original Caption Released with Image Context image for PIA02298 Crater Variety This image contains several different impact craters. The elongate depression near the top of the image is formed when more than one impactor hits at the same time (a double whammy). The large crater at the bottom formed in a single impact, but was subsequently filled with material that is now being removed. Image information: VIS instrument. Latitude 13.5N, Longitude 167.2E. 36 meter/pixel resolution. Please see the THEMIS Data Citation Note [ http://themis.la.asu.edu/terms ] for details on crediting THEMIS images. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
Crater Variety
PIA02298
Sol (our sun)
Thermal Emission Imaging Sys …
Title Crater Variety
Original Caption Released with Image Context image for PIA02298 Crater Variety This image contains several different impact craters. The elongate depression near the top of the image is formed when more than one impactor hits at the same time (a double whammy). The large crater at the bottom formed in a single impact, but was subsequently filled with material that is now being removed. Image information: VIS instrument. Latitude 13.5N, Longitude 167.2E. 36 meter/pixel resolution. Please see the THEMIS Data Citation Note [ http://themis.la.asu.edu/terms ] for details on crediting THEMIS images. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
KENNEDY SPACE CENTER, FLA. - …
Description KENNEDY SPACE CENTER, FLA. - At Ball Aerospace in Boulder, Colo., the impactor on the Deep Impact spacecraft is tested. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impact?s flyby spacecraft will collect pictures and data of how the crater forms, measuring the crater?s depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.
Release Date 01/10/2005
JET PROPULSION LABORATORY, C …
Description JET PROPULSION LABORATORY, CALIF. - The impactor of the Deep Impact spacecraft, suspended by an overhead crane, undergoes inspection in the Fischer Assembly building at Ball Aerospace in Boulder, Colo. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impact?s flyby spacecraft will collect pictures and data of how the crater forms, measuring the crater?s depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.
Release Date 01/10/2005
JET PROPULSION LABORATORY, C …
Description JET PROPULSION LABORATORY, CALIF. - At Ball Aerospace in Boulder, Colo., a thermal vacuum test is conducted on Deep Impact instruments in the instrument assembly area in the Fisher Assembly building clean room. The High Resolution Instrument (HRI, at right) is one of the largest space-based instruments built specifically for planetary science. It is the main science camera for Deep Impact, providing the highest resolution images via a combined visible camera, an infrared spectrometer and a special imaging module. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impact?s flyby spacecraft will collect pictures and data of how the crater forms, measuring the crater?s depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.
Release Date 01/10/2005
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