Browse All : Ganymede (Jupiter Moon) of Jet Propulsion Laboratory (JPL)

Ganymede's Shadow

title	Ganymede's Shadow
date	01.09.2007
description	The New Horizons Long Range Reconnaissance Imager (LORRI) took this photo of Jupiter at 20:42:01 UTC on January 9, 2007, when the spacecraft was 80 million kilometers (49.6 million miles) from the giant planet. The volcanic moon Io is to the left of the planet, the shadow of the icy moon Ganymede moves across Jupiter's northern hemisphere. Ganymede's average orbit distance from Jupiter is about 1 million kilometers (620,000 miles), Io's is 422,000 kilometers (262,000 miles). Both Io and Ganymede are larger than Earth's moon, Ganymede is larger than the planet Mercury. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Ganymede

title	Ganymede
date	02.27.2007
description	This is New Horizons' best image of Ganymede, Jupiter's largest moon, taken with the spacecraft's Long Range Reconnaissance Imager (LORRI) camera at 10:01 Universal Time on February 27 from a range of 3.5 million kilometers (2.2 million miles). The longitude of the disk center is 38 degrees West and the image scale is 17 kilometers (11 miles) per pixel. Dark patches of ancient terrain are broken up by swaths of brighter, younger material, and the entire icy surface is peppered by more recent impact craters that have splashed fresh, bright ice across the surface. With a diameter of 5,268 kilometers (3.273 miles), Ganymede is the largest satellite in the solar system. This is one of a handful of Jupiter system images already returned by New Horizons during its close approach to Jupiter. Most of the data being gathered by the spacecraft are stored onboard and will be downlinked to Earth during March and April 2007. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Io and Ganymede

title	Io and Ganymede
date	01.17.2007
description	The New Horizons Long Range Reconnaissance Imager (LORRI) took this 4-millisecond exposure of Jupiter and two of its moons at 01:41:04 UTC on January 17, 2007. The spacecraft was 68.5 million kilometers (42.5 million miles) from Jupiter, closing in on the giant planet at 41,500 miles (66,790 kilometers) per hour. The volcanic moon Io is the closest planet to the right of Jupiter, the icy moon Ganymede is to Io's right. The shadows of each satellite are visible atop Jupiter's clouds, Ganymede's shadow is draped over Jupiter's northwestern limb. Ganymede's average orbit distance from Jupiter is about 1.07 million kilometers (620,000 miles), Io's is 422,000 kilometers (262,000 miles). Both Io and Ganymede are larger than Earth's moon, Ganymede is larger than the planet Mercury. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Hubble Finds Ozone on Jupiter's Moon Ganymede

Hubble Finds Ozone on Jupite …

title	Hubble Finds Ozone on Jupiter's Moon Ganymede
description	Though ozone may be diminishing on Earth, it is being manufactured one-half billion miles away, on Jupiter's largest satellite, Ganymede. NASA's Hubble Space Telescope found ozone's spectral "fingerprint" during observations of Ganymede made by Keith Noll and colleagues at the Space Telescope Science Institute in Baltimore, Maryland. These Hubble Faint Object Spectrograph results were presented at the American Astronomical Society's 27th Annual Meeting of the Division of Planetary Sciences in Kona, Hawaii. Image Credit: NASA

Ganymede Topography

title	Ganymede Topography
description	This perspective view, simulating a low altitude flight over the surface of Ganymede, was made possible by topographic analysis of stereo images of the Sippar Sulcus region. Such a view was made possible when Galileo passed Ganymede in May 1997, providing a virtual second "eye" to Voyager's first view in 1979. Because this view covers a large area, it reveals that younger, smoother terrains are low-lying relative to older, heavily faulted terrains. The consistently low elevations of these smooth deposits has been cited as evidence for flooding of parts of Ganymede by low-viscosity lavas, most likely liquid water or water-ice slush. This view is centered at 35 degrees south, 180 degrees west. The smallest features visible are roughly 350 to 400 meters (1,150 to 1,300 feet) across. This image was prepared by the Lunar and Planetary Institute, Houston, and included in a report by Dr. Paul Schenk et al. in the March 1, 2001, edition of the journal Nature. Image Credit: NASA and Lunar and Planetary Institute

Ganymede's Nergal Crater

title	Ganymede's Nergal Crater
date	09.06.1996
description	Two impact craters surrounded by an unusual ejecta blanket dominate this high-resolution image of the surface of Jupiter's moon Ganymede. NASA's Galileo spacecraft photographed this region as it passed Ganymede during its second orbit through the jovian system. North is to the top of the picture, and the Sun illuminates the surface from the southeast. Nergal, the larger crater, is about 8 kilometers in diameter, while the smaller (unnamed) crater to its west is 3 kilometers across. The craters are situated in a region of bright grooved terrain named Byblus Sulcus, located in the northern part of Marius Regio at 390N latitude and 2010W longitude. The distinctive ejecta blanket that surrounds them is darker nearer the craters and brighter further away. The inner region of the ejecta is characterized by a lobate appearance indicative of the flow of a liquid (or slushy) substance over the surface. The flow was probably icy surface material melted by the energy released during the impact that formed the crater. The picture covers an area about 48 by 34 kilometers across at a resolution of 86 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

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

Eyeing Ganymede

title	Eyeing Ganymede
date	11.18.2000
description	Jupiter casts a baleful eye toward the moon Ganymede in this enhanced-contrast image from NASA's Cassini spacecraft. Jupiter's "eye', the Great Red Spot, was captured just before disappearing around the eastern edge of the planet. The furrowed eyebrow above and to the left of the spot is a turbulent wake region caused by westward flow that has been deflected to the north and around the Red Spot. The smallest features visible are about 240 kilometers (150 miles) across. Within the band south of the Red Spot are a trio of white ovals, high pressure counterclockwise-rotating regions that are dynamically similar to the Red Spot. The dark filamentary features interspersed between white ovals are probably cyclonic circulations and, unlike the ovals, are rotating clockwise. Jupiter's equatorial zone stretching across the planet north of the Spot appears bright white, with gigantic plume clouds spreading out from the equator both to the northeast and to the southeast in a chevron pattern. This zone looks distinctly different than it did during the Voyager flyby 21 years ago. Then, its color was predominantly brown and the only white plumes conspicuous against the darker material beneath them were oriented southwest-to-northeast. Ganymede is Jupiter's largest moon, about 50 percent larger than our own Moon and larger than the planet Mercury. The visible details in this image are different geological terrains. Dark areas tend to be older and heavily cratered, brighter areas are younger and less cratered. Cassini images of Ganymede and Jupiter's other large moons taken near closest approach on Dec. 30 will have resolutions about four times better than that seen here. This image is a color composite of ones taken with different filters by Cassini's narrow-angle camera on Nov. 18, 2000, processed to enhance contrast. Cassini 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 mission for NASA's Office of Space Science, Washington, D.C. Image Credit: NASA/JPL/University of Arizona

Ganymede's Northern Limb

title	Ganymede's Northern Limb
description	View of the Northern limb region on Ganymede showing the Galileo Regio region. North is to the bottom of the picture and the sun illuminates the surface from the left. The finest details that can be discerned in this picture are about 6.7 km across. The time is 8:45:09 UT on June 26, 1996. Image Credit: NASA

Ganymede's Northern Terminat …

title	Ganymede's Northern Terminator
description	View of the Northern terminator region on Ganymede showing the Uruk Sulcus region. North is to the bottom of the picture and the sun illuminates the surface from the left. The finest details that can be discerned in this picture are about 6.7 km across. The time is 8:45:09 UT on June 26, 1996. Image Credit: NASA

Ganymede's Bright Limb

title	Ganymede's Bright Limb
description	View of the bright limb of Ganymede showing a field of bright rayed craters in the satellites equatorial region and southern hemisphere. North is to the bottom of the picture and the sun illuminates the surface from the left. The finest details that can be discerned in this picture are about 6.7 kilometers across. The Universal Time is 8:45:09 UT on June 26, 1996. Image Credit: NASA

Europa, Ganymede, and Callisto: Surface comparison at high spatial resolution

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

Fine Details of the Icy Surface of Ganymede

Fine Details of the Icy Surf …

PIA00707

Jupiter

Solid-State Imaging

Title	Fine Details of the Icy Surface of Ganymede
Original Caption Released with Image	Dramatic view of fine details in ice hills and valleys in an unnamed region on Jupiter's moon Ganymede. North is to the top of the picture and the sun illuminates the surface from the left. The finest details that can be discerned in this picture are only 11 meters across (similar to the size of an average house) some 2000 times better than previous images of this region. The bright areas in the left hand version are the sides of hills facing the sun, the dark areas are shadows. In the right hand version the processing has been changed to bring out details in the shadowed regions that are illuminated by the bright hillsides. The brightness of some of the hillsides is so high that the picture elements "spill over" down the columns of the picture. The image was taken on June 28, 1996 from a distance of about 1000 kilometers. 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

Ganymede Global

PIA00706

Jupiter

Solid-State Imaging

Title	Ganymede Global
Original Caption Released with Image	View of Ganymede from the Galileo spacecraft during its first encounter with the Satellite. North is to the top of the picture and the sun illuminates the surface from the right. The finest details that can be discerned in this picture are about 6.7 kilometers across. The Universal Time is 8:45:09 UT on June 26, 1996. 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

Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager

Detail of Ganymede's Uruk Su …

PIA00705

Jupiter

Solid-State Imaging

Title	Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager
Original Caption Released with Image	View of the region of Ganymede's Uruk Sulcus placed on a lower resolution Voyager view taken 17 years earlier. North is to the top of the picture and the sun illuminates the surface from almost overhead in the Galileo view. The finest details that can be discerned in the Galileo picture are about 80 meters across. The four boxes outlined in white show the extent of Galileo's initial look at this area. 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

Ganymede Color Global

PIA00716

Jupiter

Solid-State Imaging

Title	Ganymede Color Global
Original Caption Released with Image	Natural color view of Ganymede from the Galileo spacecraft during its first encounter with the satellite. North is to the top of the picture and the sun illuminates the surface from the right. The dark areas are the older, more heavily cratered regions and the light areas are younger, tectonically deformed regions. The brownish-gray color is due to mixtures of rocky materials and ice. Bright spots are geologically recent impact craters and their ejecta. The finest details that can be discerned in this picture are about 13.4 kilometers across. The images which combine for this color image were taken beginning at Universal Time 8:46:04 UT on June 26, 1996. 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

Galileo Resolutions: Ganymede and the San Francisco Bay Area

Galileo Resolutions: Ganymed …

PIA00722

Jupiter

Solid-State Imaging

Title	Galileo Resolutions: Ganymede and the San Francisco Bay Area
Original Caption Released with Image	These frames demonstrate the dramatic improvement in the resolution of pictures that NASA's Galileo spacecraft is returning compared to previous images of the Jupiter system. The spacecraft's many orbits allow numerous close flyby's of Jupiter and its moons. The top left frame shows the best resolution (1.3 kilometers per picture element or pixel) data of the Uruk Sulcus region on Jupiter's moon Ganymede which was available after the 1979 flyby of the Voyager 2 spacecraft. The top right frame shows the same area as captured by Galileo during its closer flyby of Ganymede on June 27, 1996 at a range of 7,448 kilometers (4.628 miles). For comparison, the bottom frames show images of the San Francisco Bay area trimmed to the size of the Ganymede images and adjusted to similar resolutions. The Galileo image of Uruk Sulcus has a resolution of about 74 meters per pixel. The area shown is about 35 by 55 kilometers (25 by 34 miles). North is to the top, and the sun illuminates the surface from the lower left. The image taken by the Solid State Imaging (CCD) system reveals details of the structure and shape of the ridges which permit scientists to determine their origin and their relation to other terrains. These new views are helping to unravel the complex history of this planet-sized moon. The left SF Bay area image is from an image obtained by an Advanced Very High Resolution Radiometer aboard an NOAA satellite. The right SF Bay area image is from a LandSat Thematic Mapper. Golden Gate Park is clearly visible as a narrow dark rectangle towards the middle of this image. Both images were trimmed and adjusted to resolutions similar to the Ganymede images. 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

Pre-Dawn Temperatures on Gan …

PIA01145

Jupiter

Photopolarimeter-Radiometer

Title	Pre-Dawn Temperatures on Ganymede
Original Caption Released with Image	This infrared image of Jupiter's moon Ganymede, showing heat radiation from its surface at a wavelength of 27 microns (millionths of a meter), provides the best view yet of pre-dawn temperatures on Ganymede. Temperatures, derived from the brightness of the infrared radiation, can be determined from the colors by reference to the scale at the bottom of the image. The image, taken by NASA's Galileo spacecraft, shows half of Ganymede's disk as seen by the approaching spacecraft. Longitudes covered range from 340 on the right of the image, through longitude zero (the direction facing Jupiter) to longitude 60 near Ganymede's limb on the left. The morning terminator, near longitude 15, curves through the middle of the image, separating areas experiencing the last hours of the long (3.5 Earth day) Ganymede night, on the left, from areas that are warming up in the morning sunshine, on the right. Ganymede's north pole is in the upper right corner of the image, and the south pole is in the lower right. Ganymede rotates from left to right. Nighttime temperatures, shown in blue and purple colors, are in the range 85 - 100 Kelvin (-306 to -279 F). The surface cools steadily during the night, so the warmest nighttime temperatures are on the left side of the disk, and temperatures drop towards the dawn terminator on the right, before warming rapidly once the sun rises (the red, yellow and white areas on the far right). Study of the rate of nighttime cooling and the rate of post-sunrise warming, will provide information about Ganymede's surface properties. The image was taken with Galileo's PPR (Photopolarimeter-Radiometer) instrument on the spacecraft's seventh orbit around Jupiter, from a range of about 190,000 kilometers (118,060 miles). Surface temperatures derived from the strength of infrared radiation, as was done here, are called "brightness temperatures", and may be slightly in error. The PPR instrument builds up an image by slowly scanning across the target over a period of up to one hour. The motion of Galileo relative to Ganymede during this time causes distortions in the satellite shape on the image, which therefore appears slightly non-circular. The small overlapping circles that make up the image show the size of the area, about 450 kilometers (280 miles) across, covered by each individual PPR measurement. Blue spots in the dark sky in the left-hand portion of the image are due to noise. JPL manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.

Nighttime Temperatures on Ga …

PIA01146

Jupiter

Photopolarimeter-Radiometer

Title	Nighttime Temperatures on Ganymede
Original Caption Released with Image	This infrared image of Jupiter's moon Ganymede, showing heat radiation from its surface at a wavelength of about 60 microns (millionths of a meter), provides the best view yet of nighttime temperatures on this hemisphere of Ganymede. Temperatures, derived from the brightness of the infrared radiation, can be determined from the colors by reference to the scale at the bottom of the image. The image, taken by NASA's Galileo spacecraft, shows most of Ganymede's nighttime hemisphere, centered on longitude 180 degrees, with north at the top. Irregular, diagonal dark stripes result from missing data, and are not real. Part of Ganymede's illuminated crescent, warmed by the late afternoon sun and appearing pink in this representation (indicating temperatures near 110 Kelvin (-260 F), is visible in the lower left, but most of the part of Ganymede that is seen here is in darkness, glowing only because it retains some heat from the previous day. Jupiter appears in the background behind Ganymede in the upper right part of the image. Although it is nighttime on this part of Jupiter, the planet remains much warmer at night than Ganymede does, with temperatures near 140 Kelvin (- 207 F), because Jupiter's atmosphere is too dense to cool down significantly during the night, and is also warmed by heat that flows up from Jupiter's interior. The coldest parts of Ganymede that are visible (appearing dark blue) are near the north and south poles, and have temperatures below 80 Kelvin (-315 F), while parts of the equator remain at temperatures up to 100 K (-279 F) through the night, and appear in bright blue and purple colors. This same side of Ganymede was seen in full sunlight on Galileo's first orbit around Jupiter, and similar measurements showed that noontime temperatures at the equator reached 150 K (-190 F), which is 90 degrees (Fahrenheit) warmer than the night-time temperatures seen here. The image was taken with Galileo's PPR (Photopolarimeter-Radiometer) instrument on the spacecraft's seventh orbit around Jupiter, from a range of about 65,000 kilometers (40,389 miles). Surface temperatures derived from the strength of infrared radiation, as was done here, are called "brightness temperatures", and may be slightly in error. The PPR instrument builds up an image by slowly scanning across the target over a period of up to one hour. The motion of Galileo relative to Ganymede during this time causes distortions in the satellite shape on the image, which therefore appears slightly non-circular. The small overlapping circles that make up the image show the size of the area, about 160 kilometers (99 miles) across, covered by each individual PPR measurement. Blue spots in the dark sky in the lower right are due to noise. JPL manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.

Ganymede at 2.6 million mile …

PIA00351

Jupiter

Imaging Science Subsystem - …

Title	Ganymede at 2.6 million miles
Original Caption Released with Image	This photo of Ganymede, largest of Jupiter's Galilean satellites and the third from the planet, was taken shortly after midnight March 1, from a distance of 2.6 million miles (4.2 million kilometers). Ganymede is slightly larger than the planet Mercury, but is much less dense, it has = roughly twice the density of water. Ganymede's surface brightness is = four times that of Earth's Moon. This photo shows dark features = reminiscent of the dark, mare regions on the Moon. On Ganymede, however, = these features have twice the brightness of lunar mare. Scientists = believe they are unlikely to be composed of rock or lava as the Moon's = mare regions are. Ganymede's north polar region appears to be covered = with brighter material, and scientists say it could be water frost. = Later photos of Ganymede will be taken from closer range and will = therefore have higher resolution if those photos of the polar region show = underlying terrain blanketed by frost, it could indicate movement of water= across Ganymede's surface, possibly in a very thin atmosphere. Brighter = spots are also scattered across this hemisphere of Ganymede. They may be = related to impact craters, or may represent source regions of fresh ice. = JPL manages and controls the Voyager project for NASA's Office of Space = Science.

Ganymede at 87,000 miles

PIA00354

Jupiter

Imaging Science Subsystem - …

Title	Ganymede at 87,000 miles
Original Caption Released with Image	This picture of Ganymede, Jupiter's largest satellite was taken on the afternoon of March 5, 1979 from a range 145,000 km (87,000 mi). The width of the picture represents about 580 km (548 mi.) on the surface of Ganymede, and the smallest visible features are about 3 km (1.7 mi) across. The picture shows complex patterns of ridges and grooves which are probably the results of deformations of Ganymede's thick icy crust. Some systems of grooves and ridges are superposed on the ridge and groove systems indicating they are younger. A more degraded crater near the left center of the picture is crossed by ridges indicated that it predates the period of crystal deformation. JPL manages and controls the Voyager Project of NASA's Office of Space Science.

Ganymede at 3.4 million mile …

PIA00352

Jupiter

Imaging Science Subsystem - …

Title	Ganymede at 3.4 million miles
Original Caption Released with Image	This color picture of Ganymede, Jupiter's largest satellite, was taken on the afternoon of March 2, 1979, by Voyager 1 from a distance of about 3.4 million kilometers (2.1 million miles). This photograph was assembled from three black-and-white pictures in the Image Processing Laboratory at JPL. This face of Ganymede is centered on the 260=B0 meridian. Ganymede is slightly larger than the planet Mercury but has a density almost three times less than Mercury. Therefore, Ganymede probably consists in large part of ice. At this resolution the surface shows light and dark markings interspersed with bright spots. The large darkish area near the center of the satellite is crossed by irregular light streaks somewhat similar to rays seen on the Moon. The bright patch in the southern hemisphere is reminiscent of some of the larger rayed craters on the Moon caused by meteorite impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Ganymede Full Disk

PIA00353

Jupiter

Imaging Science Subsystem - …

Title	Ganymede Full Disk
Original Caption Released with Image	This picture was taken on March 4, 1979 at 2:30 A.M. PST by Voyager 1 from a distance of 2.6 million kilometers (1.6 million miles). Ganymede is Jupiter's largest satellite with a radius of about 2600 kilometers, about 1.5 times that of our Moon. Ganymede has a bulk density of only approximately 2.0 g/cc almost half that of the Moon. Therefore, Ganymede is probably composed of a mixture of rock and ice. The features here, the large dark regions, in the northeast quadrant, and the white spots, resemble features found on the Moon, mare and impact craters respectively. The long white filaments resemble rays associated with impacts on the lunar surface. The various colors of different regions probably represent differing surface materials. There are several dots on the picture of single color (blue, green, and orange) which are the result of markings on the camera used for pointing determinations and are not physical markings. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Ganymede's Northern Hemisphe …

PIA00356

Jupiter

Imaging Science Subsystem - …

Title	Ganymede's Northern Hemisphere
Original Caption Released with Image	This color reconstruction of part of the northern hemisphere of Ganymede was made from pictures taken at a range of 313,000 kilometers (194,000 miles). The scene is approximately 1,300 kilometers (806 miles) across. It shows part of dark, densely cratered block which is bound on the south by lighter, and less cratered, grooved terrain. The dark blocks are believed to be the oldest parts of Ganymede's surface. Numerous craters are visible, many with central peaks. The large bright circular features have little relief and are probably the remnants of old, large craters that have been annealed by flow of the icy near-surface material. The closely-spaced arcuate, linear features are probably analogous to similar features on Ganymede which surround a large impact basin. The linear features here may indicate the former presence of a large impact basin to the southwest.

Bright Halo Impact Crater on …

PIA00357

Jupiter

Imaging Science Subsystem - …

Title	Bright Halo Impact Crater on Ganymede
Original Caption Released with Image	his color picture of Ganymede in the region 30 S 180 W shows features as small as 6 kilometers (3.7 miles) across. Shown is a bright halo impact crater that shows the fresh material thrown out of the crater. In the background is bright grooved terrain that may be the result of shearing of the surface materials along fault planes. The dark background material is the ancient heavily cratered terrain -- the oldest material preserved on the Ganymede surface.

Ganymede - high resolution

PIA02233

Jupiter

Imaging Science Subsystem - …

Title	Ganymede - high resolution
Original Caption Released with Image	This picture of Ganymede was taken on the afternoon of March 5, from a range of 272,000 kilometers. The center of the picture lies at 13 latitude, 359 longitude. Many bright impact craters are shown that have radial ejecta patterns. These rays lie across and therefore are younger than the bright and dark background material. Many older impact craters are shown that have lost their rays probably by impact erosion. The bright background areas contain grooves and ridges that may be caused by faulting of the surface materials. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

Ganymede

PIA02252

Jupiter

Imaging Science Subsystem - …

Title	Ganymede
Original Caption Released with Image	This view of Ganymede was taken on the afternoon of March 5 from a range of 267,000 kilometers (167,000 miles). A bright rayed impact crater is prominent on the left side of the frame. The ejecta material extends for a thousand kilometers (600 miles). The rays are on top and therefore are younger than the brighter ridged and grooved terrain crossing the picture. These features may be breaks in the surface caused by faulting. Many older craters are visible that have lost their rays. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

Ganymede

PIA01972

Jupiter

Imaging Science Subsystem - …

Title	Ganymede
Original Caption Released with Image	This Voyager 2 color photo of Ganymede, the largest Galilean satellite, was taken on July 7, 1979, from a range of 1.2 million kilometers. Most of this portion of Ganymede will be imaged at high resolution during closest approach with the satellite on the evening of July 8, 1979. The photo shows a large dark circular feature about 3200 kilometers in diameter with narrow closely-spaced light bands traversing its surface. The bright spots dotting the surface are relatively recent impact craters, while lighter circular areas may be older impact areas. The light branching bands are ridged and grooved terrain first seen on Voyager 1 and are younger than the more heavily cratered dark regions. The nature of the brightish region covering the northern part of the dark circular feature is uncertain, but it may be some type of condensate. Most of the features seen on the surface of Ganymede are probably both internal and external responses of the very thick icy layer which comprises the crust of this satellite.

Ganymede

PIA01987

Jupiter

Imaging Science Subsystem - …

Title	Ganymede
Original Caption Released with Image	Voyager 1 took this picture of Jupiter's satellite Ganymede from a distance of 5 million miles (8.025 million kilometers) early on the morning of Feb. 26. Ganymede is the largest of Jupiter's 13 satellites. It is slightly larger than the planet Mercury, and has a density about twice that of water. That leads scientists to believe it is composed of a mixture of rock and ice. Ganymede is about four times brighter than Earth's Moon, and ground-based observations indicate a surface of water frost or ice. Details of the surface are not easily interpreted. The bright spot near the center of the picture is five times brighter than the Moon, and may contain more than surrounding areas. The bright pattern around the spot reminds scientists of ray craters on the Moon and Mercury, and the area may in fact be an impact crater that has exposed fresh, underlying ice. Further interpretation will require higher-resolution pictures. This color photo was taken through blue, green and orange filters and was assembled in the Image Processing Lab at Jet Propulsion Laboratory. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Ganymede's Varied Terrain

PIA01520

Jupiter

Imaging Science Subsystem - …

Title	Ganymede's Varied Terrain
Original Caption Released with Image	Voyager 2 took this picture of Ganymede as the spacecraft was nearing its encounter with the ice giant. It was taken from a range of 312,000 kilometers (195,000 miles), and it shows features down to about 5 to 6 kilometers across. Clear examples of several of the different types of terras in common on Ganymede s surface are visible (right).. The boundary of the largest region of dark ancient terrain on Ganymede can be seen to the east (right), revealing some of the light linear features which may be all that remains of a large ancient impact structure similar to the large ring structure on Callisto. The broad light regions running through the image are the typical grooved structures seen within most of the light regions on Ganymede. To the lower left is another example of what might be evidence of large scale lateral motion in Ganymede's crust. The band of grooved terrain (about 100 kilometers wide) in this region appears to be offset by 50 kilometers or more on the left hand edge by a linear feature perpendicular to it. A feature similar to this one was previously discovered by Voyager 1. These are the first clear examples of strike-slip style faulting on any planet other than Earth. Many examples of craters of all ages can be seen in this image, ranging from fresh, bright ray craters to large, subdued circular markings thought to be the "scars" of large ancient impacts that have been flattened by glacier-like flows.

Bright Ray Craters in Ganymede's Northern Hemisphere

Bright Ray Craters in Ganyme …

PIA01515

Jupiter

Imaging Science Subsystem - …

Title	Bright Ray Craters in Ganymede's Northern Hemisphere
Original Caption Released with Image	GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is of a region in the northern hemisphere near the terminator. It shows a variety of impact structures, including both razed and unrazed craters, and the odd, groove-like structures discovered by Voyager in the lighter regions. The most striking features are the bright ray craters which have a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the southern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejects patterns (such as several of the craters in the southern half of PIA01516, P21262). This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Cratering and Grooved Terrain on Ganymede

Cratering and Grooved Terrai …

PIA01516

Jupiter

Imaging Science Subsystem - …

Title	Cratering and Grooved Terrain on Ganymede
Original Caption Released with Image	This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The image shows detail on the surface with a resolution of four and a half km. This picture is just south of PIA001515 (P21161) and shows more craters. It also shows the two distinctive types of terrain found by Voyager, the darker ungrooved regions and the lighter areas which show the grooves or fractures in abundance. The most striking features are the bright ray craters which havE a distinctly "bluer" color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the northern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably "gardening" by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Ganymede's Equatorial Region

PIA01517

Jupiter

Imaging Science Subsystem - …

Title	Ganymede's Equatorial Region
Original Caption Released with Image	GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is south of PIA01516 (P21262) near the equator of Ganymede, and has relatively subdued colors in the visible part of the spectrum (later, scientists will analyze Voyager pictures taken in UV). The most striking features are the bright ray craters which have a distinctly "bluer" color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggest that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably "gardening" by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Global Map of Ganymede

PIA03781

Jupiter

Imaging Science Subsystem, I …

Title	Global Map of Ganymede
Original Caption Released with Image	The images used for the base of this Ganymede globe were chosen from coverage supplied by the Galileo solid-state imaging (SSI) camera and Voyager 1 and 2 spacecraft. The monochrome and color data were both processed using Integrated Software for Imagers and Spectrometers (ISIS). The individual images were radiometrically calibrated and photometrically normalized using a Lunar-Lambert function with empirically derived values. A linear correction based on the statistics of all overlapping areas was then applied to minimize image brightness variations. The image data were selected on the basis of overall image quality, reasonable original input resolution (from 20 km/pixel for gap fill to as much as 180 m/pixel), and availability of moderate emission/incidence angles for topography and albedo. The black and white monochrome base mosaic was constructed separately from the three-band color mosaic. Although consistency was achieved where possible, different filters were included for monochrome global image coverage as necessary: clear for Voyager 1 and 2, clear, near-IR (757 nm), and green (559 nm) for Galileo SSI. Individual images were projected to a Sinusoidal Equal-Area projection at an image resolution of 1 km/pixel. The global color mosaic was processed in Sinusoidal projection with an image resolution of 6 km/pixel. The color utilized the SSI filters 1-micron(991 nm) wavelength for red, SSI 559 nm for green, and SSI 413 nm for violet. Where SSI color coverage was lacking in the longitude range of 210°-250°, Voyager 2 wide-angle images were included to complete the global coverage. The chosen filters for the Voyager 2 data were ~530 nm for green, and ~480-500 nm for blue. The red band was synthesized in this area based on statistics calculated from the surrounding SSI 1-micron (991 nm) data and SSI and Voyager data in the blue and green bands. The final global color mosaic was then scaled up to 1 km/pixel and merged with the monochrome mosaic. The north pole and south pole regions that lack digital color coverage have been completed with the monochrome map coverage. The final global mosaic was then reprojected so that the entire surface of Ganymede is portrayed in a manner suitable for the production of a globe. A specialized program was used to create the "flower petal" appearance of the images, the area of each petal from 0 to 75 degrees latitude is in the Transverse Mercator projection, and the area from 75 to 90 degrees latitude is in the Lambert Azimuthal Equal-Area projection. The projections for adjacent petals overlap by 2 degrees of longitude, so that some features are shown twice. Names shown on the globe are approved by the International Astronomical Union. The number, size, and placement of text were chosen for a 9-inch globe. A complete list of Ganymede nomenclature can be found at the Gazetteer of Planetary Nomenclature at http://planetarynames.wr.usgs.gov. The northern hemisphere is shown on the left, and the southern hemisphere, is shown on the right.

Ice-frosted crater tops on G …

PIA00496

Jupiter

Solid-State Imaging

Title	Ice-frosted crater tops on Ganymede
Original Caption Released with Image	Scientists believe that water-ice frosts are the likely cause for the brightening seen around the circular rims of these craters located at a high northern latitude (57 degrees) on Jupiter's moon Ganymede in this image taken by NASA's Galileo spacecraft on September 6, 1996. The image, just recently radioed to Earth from the spacecraft, shows the same kind of bright, high-latitude surface areas as those first seen by the Voyager spacecraft in 1979, but at higher resolution (this image spans about 18 kilometers or 11 miles on a side). Even though the Sun is shining from the south, the north-facing walls of the ridges and craters are brighter than the walls facing the Sun. This is interpreted to mean that the very bright north-facing slopes are covered with surface water-ice frosts, and that these frosts preferentially accumulate in such high-latitude locations. Galileo scientists say that at the high resolution seen in Galileo images, the high-latitude brightness seen by Voyager is partly attributable to frosts forming on cooler, north-facing slopes. The right-hand side of the image is dominated by a north-south line of impact craters, the smallest ones at the top are about 2 kilometers (1.2 miles) in diameter and the large one at the bottom is about 5 kilometers (about 3 miles) in diameter. Ganymede is the largest moon in the solar system, larger than the planet Mercury and nearly the size of Mars. 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 Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo

Stereo View of Ganymede's Galileo Region

Stereo View of Ganymede's Ga …

PIA00521

Jupiter

Solid-State Imaging

Title	Stereo View of Ganymede's Galileo Region
Original Caption Released with Image	Topographic detail is seen in this stereoscopic view of the Galileo Regio region of Jupiter's moon Ganymede. The picture is a computer reconstruction from two images taken by NASA's Galileo spacecraft this summer. One image of the Galileo Regio region was taken June 27, 1996, at a range of 9,515 kilometers (about 5,685 miles) with a resolution of 76 meters. The other was taken September 6, 1996 at a range of 10,220 kilometers (about 6,350 miles) with a resolution of 86 meters. The topographic nature of the deep furrows and impact craters that cover this portion of Ganymede is apparent. The blue-sky horizon is artificial. The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at 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

Stereo View of Ganymede's Ga …

PIA00498

Jupiter

Solid-State Imaging

Title	Stereo View of Ganymede's Galileo Regio
Original Caption Released with Image	New topographic detail is seen in a stereoscopic view of this part of Jupiter's moon Ganymede. The newly processed picture is a computer reconstruction from two images taken by NASA's Galileo spacecraft this summer. One image of the Galileo Regio region was taken June 27, 1996, at a range of 9,515 kilometers (about 5,685 miles) and the other was taken at a range of 10,220 kilometers (about 6,350 miles) on September 6, 1996. The topographic nature of the deep furrows and impact craters that cover this portion of Ganymede is apparent. The blue-sky horizon is artificial. 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 Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo

Ganymede G1 & G2 Encounters - Interior of Ganymede

Ganymede G1 & G2 Encounters …

PIA00519

Jupiter

Title	Ganymede G1 & G2 Encounters - Interior of Ganymede
Original Caption Released with Image	Voyager images are used to create a global view of Ganymede. The cut-out reveals the interior structure of this icy moon. This structure consists of four layers based on measurements of Ganymede's gravity field and theoretical analyses using Ganymede's known mass, size and density. Ganymede's surface is rich in water ice and Voyager and Galileo images show features which are evidence of geological and tectonic disruption of the surface in the past. As with the Earth, these geological features reflect forces and processes deep within Ganymede's interior. Based on geochemical and geophysical models, scientists expected Ganymede's interior to either consist of: a) an undifferentiated mixture of rock and ice or b) a differentiated structure with a large lunar sized "core" of rock and possibly iron overlain by a deep layer of warm soft ice capped by a thin cold rigid ice crust. Galileo's measurement of Ganymede's gravity field during its first and second encounters with the huge moon have basically confirmed the differentiated model and allowed scientists to estimate the size of these layers more accurately. In addition the data strongly suggest that a dense metallic core exists at the center of the rock core. This metallic core suggests a greater degree of heating at sometime in Ganymede's past than had been proposed before and may be the source of Ganymede's magnetic field discovered by Galileo's space physics experiments. Galileo's primary 24 month mission includes eleven orbits around Jupiter and will provide observations of Jupiter, its moons and its magnetosphere. The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov.

NIMS Ganymede Surface Map

PIA00500

Jupiter

Near Infrared Mapping Spectr …

Title	NIMS Ganymede Surface Map
Original Caption Released with Image	Galileo has eyes that can see more than ours can. By looking at what we call the infrared wavelengths, the NIMS (Near Infrared Mapping Spectrometer) instrument can determine what type and size of material is on the surface of a moon. Here, 3 images of Ganymede are shown. Left: Voyager's camera. Middle: NIMS, showing water ice on the surface. Dark is less water, bright is more. Right: NIMS, showing the locations of minerals in red, and the size of ice grains in shades of blue. 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.

Calderas" on Ganymede?

PIA01614

Jupiter

Solid-State Imaging

Title	Calderas" on Ganymede?
Original Caption Released with Image	NASA's Galileo imaging camera targeted an area in Sippar Sulcus on Jupiter's moon, Ganymede. Images obtained in 1979 by NASA's Voyager spacecraft showed that the area contained curvilinear and arcuate scarps or cliffs. These features appeared to be depressions which were candidate sources for some of the water ice volcanism thought to form the bright grooved terrain on Ganymede. The high resolution Galileo images seen here reveal that one of these structures contains a lobate, flow-like feature that is the best candidate yet seen for an icy volcanic lava flow on Ganymede. The prominent depression with scalloped walls and internal terraces is about 55 kilometers (km) in length and 17 to 20 km wide. On the floor of the inner depression is a lobate flow-like deposit 7 to 10 km wide with ridges that are curved outward (and apparently downslope) toward a cross-cutting lane of grooved terrain. The morphology of this structure suggests the possibility of volcanic eruptions creating a channel and flow, and cutting down into the surface. North is to the bottom of the picture and the sun illuminates the surface from the left. The mosaic, centered at 31 degrees south latitude and 189 degrees longitude, covers an area approximately 91 by 62 kilometers. The resolution is 172 meters per picture element. The images were taken on May 7, 1997 at 15 hours, 18 minutes, 35 seconds Universal Time at a range of 17,489 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://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 ]

Ganymede's Nippur Sulcus

PIA00497

Jupiter

Solid-State Imaging

Title	Ganymede's Nippur Sulcus
Original Caption Released with Image	New terrain overlays older terrain, which overlays still older surface, in this view of part of the surface of Jupiter's moon Ganymede, taken by the camera onboard NASA's Galileo spacecraft. Galileo obtained the images that make up this mosaic when it flew past Jupiter's moon Ganymede for the second time on September 6, 1996. An area about 54 kilometers (33 miles) wide and 90 kilometers (55 miles) high is shown. Northern Marius Regio (the dark terrain at bottom), Philus Sulcus (bright terrain at center), and Nippur Sulcus (bright terrain at top) are seen illuminated by the Sun from the southeast (north is at the top). The key characteristics and relationships of the major terrain types on tectonically active Ganymede are seen at a resolution 16 times better than images taken by the Voyager spacecraft in 1979. At the bottom, the ancient dark terrain is seen to be very deformed by tectonic fractures and faults. An impact crater about 18 kilometers (about 11 miles) in diameter has been highly modified by faulting. More recent cross-cutting fractures and faults at center illustrate to scientists the sequence of events that have created the younger bright terrain. The lines in the middle left of the image are faults that are cross-cut by younger faults in the upper part of the image. The smooth band in the upper middle of the image may represent water-ice volcanic deposits flooding a fault valley. Clusters of small craters, representing ejecta transported from distant craters and re-impacting here, are seen in the middle of the photo. The images that make up this mosaic were taken at a range of about 11,620 kilometers (about 7,200 miles). 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 Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo

Fresh Impact Craters on Gany …

PIA01609

Jupiter

Solid-State Imaging

Title	Fresh Impact Craters on Ganymede
Original Caption Released with Image	Oblique view of two fresh impact craters in bright grooved terrain near the north pole of Jupiter's moon, Ganymede. The craters postdate the grooved terrain since each is surrounded by swarms of smaller craters formed by material which was ejected out of the crater as it formed, and which subsequently reimpacted onto the surrounding surface. The crater to the north, Gula, which is 38 kilometers (km) in diameter, has a distinctive central peak, while the crater to the south, Achelous, (32 km in diameter) has an outer lobate ejecta deposit extending about a crater radius from the rim. Such images show the range of structural details of impact craters, and help in understanding the processes that form them. North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 62 degrees latitude and 12 degrees longitude, covers an area approximately 142 by 132 kilometers. The resolution is 175 meters per picture element. The images were taken on April 5, 1997 at 6 hours, 33 minutes, 37 seconds Universal Time at a range of 17,531 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:// 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 ]

Dome crater Neith on Jupiter's satellite Ganymede

Dome crater Neith on Jupiter …

PIA01658

Jupiter

Solid-State Imaging

Title	Dome crater Neith on Jupiter's satellite Ganymede
Original Caption Released with Image	This image shows crater Neith, an unusual impact structure about 160 km (100 miles) in diameter, situated on Jupiter's largest satellite, Ganymede. Impact features like Neith have been called "penepalimpsests" by some investigators or "dome craters" by others and are considered to be transitional between craters and palimpsests. Palimpsests are bright, nearly circular patches that are believed to be remnant impact features. They occur also on Callisto, Ganymede's neighbor farther distant from Jupiter. Four images of Neith were obtained under low sun elevation in April 1997 during Galileo's 7th orbit around Jupiter with the Solid State Imaging (SSI) system from a distance of about 15,500 km (9,600 miles) to produce this mosaic. The pixel resolution is about 150 m/pixel - the smallest features that are still discernible are about 300 m across. The sun illuminates the scene from the right. North is approximately pointing towards the top of the mosaic. Neith is situated at about 29 degrees northern latitude and 9 degrees western longitude on Ganymede. The most striking feature in Neith is a large, circular dome about 45 km in diameter. The dome is surrounded by a wreath of rugged terrain. The wreath does not represent the original crater rim but the rim of a large central pit instead. The rim itself is barely visible and is located along the outer boundary of a relatively smooth, circular area, assumed to be the crater floor, which in turn surrounds the wreath of rugged terrain. In some parts along the rim, inward-facing scarps may be seen. The rim is not circular but appears to be petal-shaped. Outside the rim, a continuous ejecta blanket may be discerned. The morphology of impact features such as Neith results either from the response of a relatively weak target material to a high-energy impact or from long-term viscous relaxation of the surface subsequent to impact. Absolute ages derived from crater frequency measurements are model-dependent. In one crater chronology model, based on impacts dominated by asteroids, Neith may be old and very likely was formed during a period of more intense bombardment than today, about 3.9 billion years ago. In a different model, based on impacts preferentially by comets with a more or less constant impact rate, Neith may be only about 1 billion years old. 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 ].

A Tumultuous Past for Ganymede's Dark Terrain

A Tumultuous Past for Ganyme …

PIA01612

Jupiter

Solid-State Imaging

Title	A Tumultuous Past for Ganymede's Dark Terrain
Original Caption Released with Image	Dark terrain of Nicholson Regio on Jupiter's moon, Ganymede. On the left is a crater that has been torn apart by tectonic forces. A lane of ridges and grooves (probably extensional fault blocks) cuts through the crater and distorts its originally circular shape. Though such deformation is more typical of Ganymede's bright grooved terrain, this image demonstrates that extreme tectonic disruption has occurred in the satellite's dark terrain also. The pair of oblong craters on the right was formed by the impact of a gravitationally bound pair of asteroids or a split comet. The oblong shapes of the craters suggest that the impactors struck the surface at a shallow angle. Toward the top left, an old crater has been partially buried by dark ejecta tossed from another impact about 50 kilometers to the north of this image. North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 14 degrees south latitude and 352 degrees longitude, covers an area approximately 111 by 93 kilometers. The resolution is 180 meters per picture element. The image was taken on April 5, 1997 at 6 hours, 31 minutes, 44 seconds Universal Time at a range of 17,840 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://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 ]

Marius Regio, Ganymede

PIA01617

Jupiter

Solid-State Imaging

Title	Marius Regio, Ganymede
Original Caption Released with Image	This image shows a highly fractured lane of grooved terrain, Lagash Sulcus, which runs through an area of heavily cratered dark terrain within Marius Regio on Jupiter's moon Ganymede. The boundary between these two units is marked by a deep trough. Outside the groove lane, little fracturing is evident, suggesting that deformation is largely concentrated within the bright grooved area. The bright, heart-shaped feature just below the image center may be a patch of bright terrain, or the feature may be related to ancient impact event. North is to the top of the picture and the sun illuminates the surface from the upper right. The image, centered at 17 degrees south latitude and 156 degrees longitude, covers an area approximately 230 by 230 kilometers. The resolution is 288 meters per picture element. The images were taken on June 6, 1997 at 14 hours, 56 minutes, 11 seconds Universal Time at a range of 28655 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:// 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 ]

Regional View of Ganymede

PIA01618

Jupiter

Solid-State Imaging

Title	Regional View of Ganymede
Original Caption Released with Image	View of the Marius Regio and Nippur Sulcus area of Jupiter's moon, Ganymede showing the dark and bright grooved terrain which is typical of this satellite. This regional scale view was imaged near the terminator (the line between day and night) and provides geologic context for small areas that were imaged at much higher resolution earlier in the tour of NASA's Galileo spacecraft through the Jovian system. The older, more heavily cratered dark terrain of Marius Regio is rutted with furrows, shallow troughs perhaps formed as a result of ancient giant impacts. Bright grooved terrain is younger and is formed through tectonism probably combined with icy volcanism. The lane of grooved terrain in the lower left, Byblus Sulcus [ http://photojournal.jpl.nasa.gov/catalog/PIA01088 ], was imaged during the spacecraft's second orbit, as were Philus Sulcus and Nippur Sulcus [ http://photojournal.jpl.nasa.gov/catalog/PIA00497 ], seen here in the upper left. Placing the small higher resolution targets of Galileo's second orbit into the context of more distant, lower resolution views of the areas surrounding and connecting them, and imaging them along Ganymede's terminator, allows for an integrated understanding of Ganymede' s geology. North is to the top left of the picture and the sun illuminates the surface from the lower right. The image, centered at 43 degrees latitude and 194 degrees longitude, covers an area approximately 664 by 518 kilometers. The resolution is 940 meters per picture element. The image was taken on May 7, 1997 at 12 hours, 50 minutes, 11 seconds Universal Time at a range of 92,402 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://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 ]

Pedestal craters Gula and Achelous on Ganymede

Pedestal craters Gula and Ac …

PIA01660

Jupiter

Solid-State Imaging

Title	Pedestal craters Gula and Achelous on Ganymede
Original Caption Released with Image	This image shows a Galileo high-resolution mosaic of craters Gula (top), about 40 km (25 miles) in diameter, and Achelous (bottom), about 35 km (21.8 miles) in diameter, projected on a lower-resolution background of image data that were obtained in the late 70s by the NASA Voyager spacecraft. The two Galileo frames used for the mosaic of Gula and Achelous were taken under low sun elevation in April 1997 during Galileo's 7th orbit around Jupiter with the Solid State Imaging (SSI) camera system onboard this NASA spacecraft that has been orbiting Jupiter since December 1995. The images were taken from a distance of about 17,500 km from Ganymede. The pixel resolution is about 180 m/pixel - the smallest features that are still discernible are about 360 m across. The sun illuminates the scene from the right. North is pointing towards the top of the Galileo mosaic. Both craters are situated between 60 and 65 degrees northern latitude at about 12.5 degrees western longitude. A characteristic feature of both craters, almost identical in size, is the "pedestal" - an outward-facing, relatively gently sloped scarp that terminates the continuous ejecta blanket. Similar features may be seen in ejecta blankets of Martian craters, suggesting impacts into a volatile (ice)-rich target material. Furthermore, both craters appear crisp and feature terraces. Gula has a prominent central peak, Achelous instead may show the remnant of a collapsed central peak or a central pit that is not fully formed. On lower-resolution images taken under higher sun illumination angle, both craters are shown to have extended bright rays, especially Achelous, which demonstrates that these two craters are younger than the respective surrounding landscape. 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 ].

Buto Facula - A palimpsest o …

PIA01659

Jupiter

Solid-State Imaging

Title	Buto Facula - A palimpsest on Ganymede
Original Caption Released with Image	This image shows a mosaic of Buto Facula, a so-called "palimpsest" situated in Marius Regio on Jupiter's largest satellite Ganymede. Palimpsests are bright, nearly circular patches that are believed to be remnant impact features. They preferentially, but not exclusively, occur in Ganymede's more densely cratered, older, dark terrain units and may also be found on Ganymede's outer neighbor Callisto. The higher resolution digital image data in the center were obtained by the Solid State Imaging (SSI) camera system onboard the NASA spacecraft Galileo in May 1997 during Galileo's 8th orbit around Jupiter from a distance of about 18,600 km (11,560 miles). The pixel resolution is 180 m/pixel - the smallest features that are still discernible are about 360 m across. The sun illuminates the scene from the right at low angle, so morphological features are accentuated by long shadows. North is pointing towards the top of the mosaic. The lower resolution context in the background is given by Voyager images from 1979 when that spacecraft passed through the Jovian system at far greater distance from Ganymede than Galileo. The image center is about 12 degrees north of Ganymede's equator at a longitude of 24 degrees East. From the center of Buto Facula outward, several morphological zones can be distinguished. The center of the palimpsest, about 40 to 50 km (25 to 31 miles) in diameter, is dominated by a relatively smooth (at SSI resolution) area that shows isolated small hills near the limit of resolution. The outline of the smooth area is roughly elliptical and in some parts petal-shaped. Also, inward-facing scarps occur along some parts of the outer boundary of the inner zone. The next outer zone is characterized by a much rougher surface and two to three almost circular ridges that don't form closed circles but rather concentric ring arcs instead. These ridges are about 40 km apart. The outermost zone is somewhat less rough than the ridge-arc zone and shows vestiges of underlying topographic features such as dark-terrain furrows and, as seen in the northeastern part of the mosaic, covers about half of an older crater. The outward boundary of Buto Facula, about 290 km (180 miles) across, is defined by a clear albedo difference on lower-resolution Voyager images taken at higher sun illumination angle, whereas on low-sun SSI frames, chains of presumably secondary craters appear just outside of the boundary zone. This is good evidence for Buto Facula being an impact structure. A younger, fresh impact crater, about 20 km (12.5 miles) in diameter, cuts one of the ridges. Several clusters of secondaries within Buto Facula may be associated with this crater. A narrow, linear, NE-SW oriented scar about 40 km long very likely represents a crater chain whose individual craters are not well distinguishable at this resolution. Similar features may be observed elsewhere on Ganymede. Currently, there are two models that describe the origin of palimpsests. In one, model, the morphology of these features was almost completely erased by viscous surface relaxation that took place over several 100 million years. According to another model, the palimpsest morphology formed almost immediately subsequent to the impact of a high-velocity projectile that punched through the crust into a liquid or plastic layer, excavating highly mobilized material that was emplaced as a slush or slurry across the surface. Densities of craters superimposed on surface features such as palimpsests are used to compare older and younger surface units. Absolute ages derived from crater densities, however, are model-dependent. In one crater chronology model, based on impacts dominated by asteroids, palimpsests may be rather old features, pointing back in time to a period of more intense bombardment than today, and may have ages on the order of 3.8 to 4 billion years. In a different model, based on impacts preferentially by comets with a more or less constant impact rate, palimpsests can be as "young" as only a few hundred million years. 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 ].

High Latitude "Bright" and "Dark" Terrains on Ganymede

High Latitude "Bright" and " …

PIA01608

Jupiter

Solid-State Imaging

Title	High Latitude "Bright" and "Dark" Terrains on Ganymede
Original Caption Released with Image	During Galileo's second orbit, a series of images were obtained within the northern polar cap of Jupiter's moon, Ganymede, across a north-south trending boundary between the grooved terrain of Philae Sulcus and the dark terrain of Galileo Regio. The blurry appearing background of this scene is the best Voyager image of the area, at a resolution of about 1.4 kilometers per picture element. The Voyager data shows that the grooved terrain of Philae Sulcus to the west (left) is bright, and the older terrain of Galileo Regio to the east (right) is dark, however, this brightness difference is not at all apparent in the high resolution Galileo images. Instead, bright and dark patches occur in both Philae Sulcus and in Galileo Regio. The bright patches occur mostly on the north and east facing slopes of craters and ridges [ http://photojournal.jpl.nasa.gov/catalog/PIA00496 ], which are expected to be colder, and therefore to collect frost in this high latitude region. The principal way that Ganymede's terrain types can be distinguished in the high resolution Galileo images is by their texture: the "bright" grooved terrain shows north-south trending ridges and grooves, and the ancient "dark" terrain shows a rolling appearance and is more heavily cratered. North is to the top of the picture and the sun illuminates the surface from the lower right. The image, centered at 63 degrees latitude and 168 degrees longitude, covers an area approximately 94 by 64 kilometers. The finest details that can discerned in this picture are about 92 meters across. The images were taken on September 6, 1996 beginning at 18 hours, 52 minutes, 46 seconds Universal Time at a range of 2266 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:// 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 ]

Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context

Ganymede Uruk Sulcus High Re …

PIA00579

Jupiter

Solid-State Imaging

Title	Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context
Original Caption Released with Image	A mosaic of four Galileo high-resolution images of the Uruk Sulcus region of Jupiter's moon Ganymede (Latitude 11 N, Longitude: 170 W) is shown within the context of an image of the region taken by Voyager 2 in 1979, which in turn is shown within the context of a full-disk image of Ganymede. North is to the top of the picture, and the sun illuminates the surface from the lower left, nearly overhead. The area shown is about 120 by 110 kilometers (75 by 68 miles) in extent and the smallest features that can be discerned are 74 meters (243 feet) in size in the Galileo images and 1.3 kilometers (0.8 miles) in the Voyager data. The higher resolution Galileo images unveil the details of parallel ridges and troughs that are principal features in the brighter regions of Ganymede. High photometric activity (large light contrast at high spatial frequencies) of this ice-rich surface was such that the Galileo camera's hardware data compressor was pushed into truncating lines. The north-south running gap between the left and right halves of the mosaic is a result of line truncation from the normal 800 samples per line to about 540. The images were taken on 27 June, 1996 Universal Time at a range of 7,448 kilometers (4,628 miles) through the clear filter of the Galileo spacecraft's imaging system. Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory 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 Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

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