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Subsection of Nirgal Vallis
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Subsection of Nirgal Vallis Image |
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This image is a subsection of the MGS Nirgal Vallis "B" image (PIA00942). This subsection of frame P006_05 is shown here at reduced resolution because the full image is almost 7 MBytes in size. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combined to significantly distort the image. However, even in this reduced resolution version, dunes can be seen in the canyon and in areas on the upland surface around the canyon. Nigral Vallis is one of a number of canyons called valley networks or runoff channels. Much of the debate concerning the origin of these valleys centers on whether they were formed by water flowing across the surface, or by collapse and upslope erosion associated with groundwater processes. At the resolution of this image, it is just barely possible to discern an interwoven pattern of lines on the highland surrounding the valley, but it is not possible to tell whether this is a pattern of surficial debris (sand or dust), as might be expected with the amount of crater burial seen, or a pattern of drainage channels. With 4X better resolution from its mapping orbit, MOC should easily be able to tell the difference between these two possibilities. Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The spacecraft has been using atmospheric drag to reduce the size of its orbit for the past three weeks, and will achieve a circular orbit only 400 km (248 mi) above the surface early next year. Mapping operations begin in March 1998. At that time, MOC narrow angle images will be 5-10 times higher resolution than these pictures. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Photo Credit: NASA/JPL/Malin Space Science Systems MRPS #84722 100297_7 605.crp, a subsection of 605.str/MOC212B 559303731.605 P006_05 |
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Rotated Perspective View of
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Rotated Perspective View of Nirgal Vallis |
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This is the full-resolution, rotated perspective image of Nirgal Vallis, a subset of PIA00942. Nigral Vallis is one of a number of canyons called valley networks or runoff channels. Much of the debate concerning the origin of these valleys centers on whether they were formed by water flowing across the surface, or by collapse and upslope erosion associated with groundwater processes. At the resolution of this image, it is just barely possible to discern an interwoven pattern of lines on the highland surrounding the valley, but it is not possible to tell whether this is a pattern of surficial debris (sand or dust), as might be expected with the amount of crater burial seen, or a pattern of drainage channels. With 4X better resolution from its mapping orbit, MOC should easily be able to tell the difference between these two possibilities. Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The spacecraft has been using atmospheric drag to reduce the size of its orbit for the past three weeks, and will achieve a circular orbit only 400 km (248 mi) above the surface early next year. Mapping operations begin in March 1998. At that time, MOC narrow angle images will be 5-10 times higher resolution than these pictures. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Photo Credit: NASA/JPL/Malin Space Science Systems MRPS #84704 100197_8 605.obl.sub.str/MOC212E 559303731.605 P006_05 |
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MGS Views of Nirgal Vallis
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MGS Views of Nirgal Vallis |
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At 3:08:30 AM on September 21, 1997, the MOC field of view swept across the highland valley network Nirgal Vallis at 28.5°S, 41.6 W. Although the MGS spacecraft was at an altitude of about 400 km (250 miles), the MOC was pointed obliquely across the planet at about 35°, so the distance to Nirgal Vallis was closer to 800 km (500 miles). At that range and viewing angle, the MOC field of view was about 16 km (10 miles) wide, and the resolution was about 9 meters (30 feet) per pixel. The acquired image is 36 km (23 miles) long. Five images are shown above: (A) is an excerpt from the USGS MDIM, roughly 180 km (112 mile) square. The small box outlines the MOC image acquisition. (B) is MOC frame P006_05, shown here at reduced resolution because the full image is almost 7 MBytes in size. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combined to significantly distort the image. However, even in this reduced resolution version, dunes can be seen in the canyon and in areas on the upland surface around the canyon. (C) shows a portion of P006_05 at the full resolution of the data. This view shows the dunes more clearly, and also illustrates better the distortion introduced by the method of data acquisition. (D) shows P006_05 skewed and rotated to the perspective that MOC was viewing at the time the image was taken. (E) shows a full-resolution version of a portion of the rotated perspective view. Nigral Vallis is one of a number of canyons called valley networks or runoff channels. Much of the debate concerning the origin of these valleys centers on whether they were formed by water flowing across the surface, or by collapse and upslope erosion associated with groundwater processes. At the resolution of this image, it is just barely possible to discern an interwoven pattern of lines on the highland surrounding the valley, but it is not possible to tell whether this is a pattern of surficial debris (sand or dust), as might be expected with the amount of crater burial seen, or a pattern of drainage channels. With 4X better resolution from its mapping orbit, MOC should easily be able to tell the difference between these two possibilities. Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The spacecraft has been using atmospheric drag to reduce the size of its orbit for the past three weeks, and will achieve a circular orbit only 400 km (248 mi) above the surface early next year. Mapping operations begin in March 1998. At that time, MOC narrow angle images will be 5-10 times higher resolution than these pictures. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor, Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Photo Credit: NASA/JPL/Malin Space Science Systems MRPS #84721 100297_2 605.all.str consisting of 605.ctx.str/MOC212A, 605.str/MOC212B, 605.sub.str/MOC212C, 605.obl.str/ MOC212D, and 605.obl.sub.str/MOC212E 559303731.605 P006_05 |
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Athabasca Vallis Streamlined
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Athabasca Vallis Streamlined "Islands |
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Tremendous floods carved these tear drop-shaped landforms in Athabasca Vallis in the Cerberus region, south of the Elysium volcanoes. The orientation of the streamlined forms indicate that the fluid flowed from the right/upper right toward the left/lower left (from the northeast to the southwest). Similar features occur in central and eastern Washington in the northwestern United States. The examples in Washington formed when massive amounts of water rushed across the landscape, scouring a "channeled scabland" during the last Ice Age, roughly 12,000-13,000 years ago. The features on Mars are much older, while the absolute age cannot be determined, the small impact craters with rayed ejecta patterns on the flood surfaces indicate it must be much, much older than the flood landscape in Washington. This is a mosaic of six Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images acquired in 1999 through 2002. Illumination is from the left. The mosaic covers an area 11.9 km (7.4 mi) by 13.0 km (8.1 mi). The full-size mosaic has a resolution of 4 meters (13 ft) per pixel. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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Nirgal Vallis
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Nirgal Vallis |
| Description |
This THEMIS image shows a sinuous valley network channel with sharp bends cutting across the cratered highlands of the southern hemisphere of Mars. The channel is named Nirgal Vallis, which is from the Babylonian word for "Mars". Nirgal Vallis is a channe l with a total length of approximately 500 km. It is approximately 6 km wide in this region. Gullies and alluvial deposits discovered by Mars Global Surveyor are clearly visible on the polar-facing (south) wall and floor of Nirgal Vallis. These gullies a ppear to emanate from a specific layer in the walls. There is a pronounced sparsity of gullies on the equator-ward facing slopes. The gullies have been proposed to have formed by the subsurface release of water. Patches of dunes are also seen on the chann el floor, notably along the edges of the channel floor near the canyon walls. There is still debate within the scientific community as to how valley networks themselves form: surface runoff (rainfall/snowmelt) or headward erosion via groundwater sapping. This image is approximately 22 km wide and 60 km in length, north is toward the top. Photo Credit: NASA/JPL/Arizona State University |
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Nirgal Vallis and its Windbl
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Nirgal Vallis and its Windblown Dunes |
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Nirgal Vallis is a narrow valley system that stretches approximately 420 kilometers (260 miles) across the martian surface near 28°S latitude, north of the large basin, Argyre. The floor of the valley system is largely covered with light-toned dunes and ripples. These windblown features obscure most of the original morphology of the valley floor. This view of a small portion of Nirgal Vallis was obtained by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during Extended Mission subphase E02 on March 29, 2001. In each short tributary valley, dunes have a somewhat different orientation compared to those in the other valleys. The dune patterns here indicate that winds are locally controlled by the shape and orientation of each valley. The dunes just left of the center of the image have small craters on them, formed by meteor impact. The craters indicate that the dunes are not fresh, modern features, but are considerably older than they might at first seem. This image covers an area 3 km (1.9 mi) wide and is illuminated from the upper left. Image Credit: NASA/JPL/Malin Space Science Systems |
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Megaripples in Athabasca Val
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Megaripples in Athabasca Vallis |
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Researchers' goal in taking this image was to look for boulders in the large ripples formed by an ancient catastrophic flood in Mars' Athabasca Vallis. The Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft captured this image on Dec. 25, 2003, with use of an enhanced-resolution technique called compensated pitch and roll targeted observation. The flood-deposited megaripples had been seen in earlier, lower-resolution images from the same camera. They are the only good examples known of ripples formed in a giant catastrophic flood anywhere on Mars. Their presence indicates that large amounts of water poured rapidly through this area, based on resemblance to similar megaripples in catastrophic flood sites on Earth. The ripples in Athabasca Vallis were buried for some period and later exhumed. Strange, round features on top of some of the ripples and the adjacent plains are products of erosion and removal of the overlying layer. Finding boulders in the ripples would help constrain estimates of the power of the floods. However, the image does not show boulders in the ripples, implying either that the rocks that make up these features are smaller than about 1 to 2 meters (3 to 7 feet) in diameter or that the ripple sediments have not been completely exhumed. The image covers an area 3 kilometers (2 miles) wide, near 9.5 degrees north latitude and 203.7 degrees west longitude. Pixel size is about 1.5 meters (5 feet) by one-half meter (1.6 feet). North is up and sunlight illuminates the scene from the lower left. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Nanedi Vallis
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Nanedi Vallis |
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This picture of a canyon on the Martian surface was obtained a few minutes after 10 PM PST, January 8, 1998 by the Mars Orbiter Camera (MOC), during the 87th orbit around Mars of the Mars Global Surveyor spacecraft. It shows the canyon of Nanedi Vallis, one of the Martian valley systems cutting through cratered plains in the Xanthe Terra region of Mars. The picture covers an area 9.8 km by 18.5 km (6.1 mi by 11.5 mi), and features as small as 12 m (39 ft) can be seen. The canyon is about 2.5 km (1.6 mi) wide. Rocky outcrops are found along the upper canyon walls, weathered debris is found on the lower canyon slopes and along the canyon floor. The origin of this canyon is enigmatic: some features, such as terraces within the canyon (as seen near the top of the frame) and the small 200 m (660 ft) wide channel (also seen near the top of the frame) suggest continual fluid flow and downcutting. Other features, such as the lack of a contributing pattern of smaller channels on the surface surrounding the canyon, box-headed tributaries, and the size and tightness of the apparent meanders (as seen, for example, in the Viking image 89A32), suggest formation by collapse. It is likely that both continual flow and collapse have been responsible for the canyon as it now appears. Further observations, especially in areas west of the present image, will be used to help separate the relative effects of these and other potential formation and modification processes. Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Photo Credit: NASA/JPL/Malin Space Science Systems |
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