PIA05447.jpg = PIA05447: Middle-Latitude Craters
26 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows two craters and a rough-textured surface in Icaria Planum near 44.5°S, 109.8°W. Both craters have been buried by a thin mantle of material that eroded to form a rough texture. The ejecta pattern from the smaller of the two craters is still apparent through this mantle. While this is a southern mid-latitude surface, similar textures and thinly-buried craters are common at northern mid-latitudes, as well. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05447: Middle-Latitude Craters sur le site de la NASA.PIA05026: 18 Minutes After Beagle 2 Landing
31 December 2003
This oblique Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image shows the Beagle 2 landing zone about 18 minutes after the probe was scheduled to touch down on 25 December 2003. Mars Global Surveyor passed to the west of the site shortly after touch-down, so this image was taken looking east. The white ellipse shows the approximate location of the landing site. The largest crater to the northwest (toward upper left) of the ellipse is about 28 km (17.4 mi) across. The image is streaked and has low contrast because of the combined effects of looking obliquely and the presence of a thin veil of dust that not only hung over this region, but over most of Mars on 25 December 2003. During the previous 2 weeks, a large dust storm, followed by several smaller regional-scale storms, lifted dust in the western hemisphere of Mars. This dust drifted over most of the planet, reducing contrast and degrading the quality of MGS MOC images such as this one. This MOC image is important because it shows that there were no dust storms or other weather phenomena happening at the landing site the day Beagle 2 arrived. The landing site is located in Isidis Planitia near 11°N, 269.7°W. Sunlight illuminates the scene from the lower left.
This and several other images processed by Malin Space Science Systems, Inc. were shown by the Beagle 2 team during a press conference on 29 December 2003. These and other Beagle 2 images can be seen at:
http://www.beagle2.com/resources/landingphotos.htm. The Beagle 2 web site is at:
http://www.beagle2.com. Weekly weather reports for the Beagle 2 and Mars Exploration Rover sites, based on MOC image analysis, can be seen at:
http://www.msss.com/mars_images/moc/mer_weather.
Voir l'image PIA05026: 18 Minutes After Beagle 2 Landing sur le site de la NASA.PIA04903: Devil-Streaked Crater
MGS MOC Release No. MOC2-562, 2 December 2003
This September 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of dark streaks created during the recent southern spring by dust devils as they passed over and around an old, nearly filled, meteor impact crater. The circular feature is the former crater; the dark dots and specks on its rims are boulders. Dust devils create streaks by removing or disrupting thin coatings of fine, bright, dust on the surface. These are ephemeral features that will disappear before the next spring arrives in 2005. The crater is located near 57.4°S, 234.0°W. The image covers an area 3 km (1.9 mi) wide and is illuminated from the upper left.
Voir l'image PIA04903: Devil-Streaked Crater sur le site de la NASA.PIA04793: Polygon Patterns
MGS MOC Release No. MOC2-511, 12 October 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygon patterns, enhanced by frost in the cracks that outline the polygon forms, in the south polar region of Mars. On Earth, patterns such as this usually indicate the presence of ice in the subsurface. The same might be true for Mars. This picture is located near 70.6°S, 309.5°W, and covers an area 3 km (1.9 mi) wide. The image is illuminated by sunlight from the upper left.
Voir l'image PIA04793: Polygon Patterns sur le site de la NASA.PIA04794: Pavonis Wind Streaks
MGS MOC Release No. MOC2-512, 13 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows wind tails and streaks formed in fine sediment that mantles the upper southwest slopes of the equatorial volcano, Pavonis Mons. On the large martian volcanoes, winds tend to blow downslope. The streaks shown here are evidence of the powerful ability for the thin atmosphere over the martian volcanoes to transport sediment. This picture is located near 0.1°N, 113.8°W, and covers an area 3 km (1.9 mi) wide. The image is illuminated by sunlight from the lower left.
Voir l'image PIA04794: Pavonis Wind Streaks sur le site de la NASA.PIA05916: Sand Dunes with Frost
9 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of frost-covered sand dunes in the north polar region of Mars in early spring, 2004. The dunes indicate wind transport of sand from left to right (west to east). These landforms are located near 78.1°N, 220.8°W. This picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05916: Sand Dunes with Frost sur le site de la NASA.PIA04745: The Cydonia "D&M Pyramid" Landform
MGS MOC Release No. MOC2-484, 15 September 2003
Images of the Cydonia region of Mars continue to be popular among visitors to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
web site. The two pictures (one annotated, the other not) are mosaics of two images from MGS MOC and one from the Mars Odyssey Thermal Emission Imaging System visible camera (THEMIS VIS). The mosaics highlight a Cydonia landform popularly known as the "D&M Pyramid." It is located near 40.7°N, 9.6°W.
Although it is not really shaped like a pyramid, the Cydonia landform is one of thousands of massifs, buttes, mesas, knobs, and blocks that mark the transition from the far northwestern Arabia Terra cratered highlands down to the northeastern Acidalia Planitia lowlands. Each block, whether shaped like a face, a pyramid, or simply a mesa, massif, or knob, is a remnant of the bedrock of northeastern Arabia that was left behind as erosion slowly degraded the terrain along this zone between the highlands and the lowlands. A few outcroppings of layers in this ancient bedrock can be seen in the mosaic of the pyramid-like landform shown here; much of the landform is covered with eroded mantling material that was deposited long after this highlands remnant became an isolated feature in Cydonia.
The mosaic was created from two MOC images obtained in June (R06-00469) and July (R07-00422) of 2003 and one THEMIS VIS image acquired in 2002 (V01024003). The mosaic is 8 km by 8 km (5 mi by 5 mi) across and each of the three images is illuminated from the lower left. North is up. The picture on the right shows the location of the two MOC images as black outlines; the THEMIS image not only covers the gap between the two MOC images, it also fills out the lower left and upper right corners.
In recent weeks, the MOC team has received numerous requests through the
Mars Orbiter Camera Target Request Site to obtain pictures of the "D&M Pyramid." The images shown here were acquired before the public target suggestion effort began in August 2003, but they have not yet been archived with the NASA Planetary Data System. In the future, the MOC team hopes--depending upon whether the spacecraft flies over this area again before the end of the mission--to fill the remaining gap and obtain some 1.5 m/pixel images of the landform, based on the many public suggestions that have been received.
Other, previous MOC data and captioned releases regarding Cydonia landforms can be seen by visiting
http://www.msss.com/mars_images/moc/themes/CYDONIA.html and the
MOC Gallery.Voir l'image PIA04745: The Cydonia "D&M Pyramid" Landform sur le site de la NASA.PIA04978: Sediments of Ophir
MGS MOC Release No. MOC2-579, 19 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in December 2003, shows light-toned sedimentary rocks (bottom half of image) and dark-toned sand dunes and ripples (top half of image). The light-toned, wind-eroded rocks are formed of ancient sediments; while the dark-toned, wind-blown dunes and ripples are modern sediments. This picture is located in Ophir Chasma near 4.4°S, 71.1°W. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA04978: Sediments of Ophir sur le site de la NASA.PIA05021: Polar Polygons
26 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture displays polygons outlined by cracks in the martian south polar region. This southern summer view was acquired in October 2003 and is located near 86.9°S, 170.6°W. Polygons similar in size and shape to these are common in the arctic and antarctic regions of Earth. On Earth, they indicate the presence (or the past presence) of ground ice and the freeze-thaw cycles that accompany this ice. On Mars, whether ground ice was responsible for these landforms is uncertain, but their presence is suggestive that ground ice may exist or may once have existed in this region. The picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05021: Polar Polygons sur le site de la NASA.PIA04904: Exhuming Crater in Northeast Arabia
MGS MOC Release No. MOC2-563, 3 December 2003
The upper crust of Mars is layered, and interbedded with these layers are old, filled and buried meteor impact craters. In a few places on Mars, such as Arabia Terra, erosion has re-exposed some of the filled and buried craters. This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The larger circular feature was once a meteor crater. It was filled with sediment, then buried beneath younger rocks. The smaller circular feature is a younger impact crater that formed in the surface above the rocks that buried the large crater. Later, erosion removed all of the material that covered the larger, buried crater, except in the location of the small crater. This pair of martian landforms is located near 17.6°N, 312.8°W. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04904: Exhuming Crater in Northeast Arabia sur le site de la NASA.PIA04976: Buried Mid-Latitude Craters
MGS MOC Release No. MOC2-577, 17 December 2003
This September 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows six circular features, three of which exhibit concentric, or "bullseye," patterns within them. Each circular feature is the remains of a partly-buried, partly-eroded, and partly-filled meteor impact crater. These occur in northeastern Arabia Terra. Areas such as this, located near the middle latitudes of Mars, commonly have a "scabby" or roughened appearance. The cause of this "terrain roughening" texture is unknown, although some scientists have speculated that it might result from the erosion and removal (by way of sublimation) of ground ice. This idea remains highly speculative. These features are located near 28.4°N, 317.5°W. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA04976: Buried Mid-Latitude Craters sur le site de la NASA.PIA04737: Oblique Olympus Mons
MGS MOC Release No. MOC2-479, 10 September 2003
This is a red camera wide angle view of the giant martian volcano, Olympus Mons, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). The volcano is large enough to cover much of the U.S. state of New Mexico. This view was taken looking west toward the sunward limb of the planet. The limb is the horizon to the left; the dark band is outer space. Sunlight illuminates this scene from the lower left.
Voir l'image PIA04737: Oblique Olympus Mons sur le site de la NASA.PIA04855: Cracked and Pitted Plain
MGS MOC Release No. MOC2-536, 6 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical view--at 1.5 meters (5 feet) per pixel--of surfaces in far western Utopia Planitia. In this region, the plains have developed cracks and pit chains arranged in a polygonal pattern. The pits form by collapse along the trend of a previously-formed crack. This picture is located near 45.0°N, 275.4°W. This April 2003 image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA04855: Cracked and Pitted Plain sur le site de la NASA.PIA05498: Cerberus Fossae Trough
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a trough in the Cerberus region of Mars formed by faults as the crust in this area was pulled apart. The trough walls and floor have a few large boulders on them, and some large windblown ripples are also present. The image is located near 9.1°N, 197.1°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05498: Cerberus Fossae Trough sur le site de la NASA.PIA04860: Circular Mesa
MGS MOC Release No. MOC2-538, 8 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a circular mesa in northeast Arabia Terra. The circularity suggests that this landform might be similar to other circular mesas, found elsewhere on Mars. In those other cases, the mesa was once a meteor impact crater. The crater was filled with sediment, the sediment was cemented to become rock, and later erosion removed all of the material surrounding the former crater, leaving it standing alone as a circular mesa. This image is located near 23.7°N, 319.0°W, and covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left.
Voir l'image PIA04860: Circular Mesa sur le site de la NASA.PIA05252: Sedimentary Rocks in Ladon Vallis
25 January 2004
This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture of an outcrop of light-toned, layered, sedimentary rock exposed by erosion in Ladon Vallis. These rocks preserve clues to the martian past. However, like books in a library, one needs to go there and check them out if one wishes to read what the layers have to say. This November 2003 picture is located near 21.1°S, 29.8°W, and covers an area 3km (1.9 mi.) wide. Sunlight illuminates the scene from the left.
Voir l'image PIA05252: Sedimentary Rocks in Ladon Vallis sur le site de la NASA.PIA05699: Craters and Wind Streaks
25 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of small wind tails or streaks in the lees of impact craters in northeastern Tharsis near 25.8°N, 89.0°W. The streak tails point toward the east/northeast (right), indicating that the dominant winds blow from the west/southwest (left). This February 2004 picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05699: Craters and Wind Streaks sur le site de la NASA.PIA05229: Reconstructing the Scene of Landing
Figure 2
Meridiani Destinations
April 8, 2004
The starting point and planned destinations for surface travels of NASA's Mars Exploration Rover Opportunity are indicated on this image of territory within Mars' Meridiani Planum region (Figure 2). Opportunity landed on Jan. 24, 2004, (Universal Time) in the small bowl later nicknamed "Eagle Crater." After about two months of examining rocks and soils within that crater, the rover set out toward a larger crater informally named "Endurance." During an extended mission following its three-month prime mission, Opportunity may finish examining Endurance, then head for a type of landscape to the southeast called "etched terrain." There, additional deposits of layered bedrock may lie exposed. The underlying image for the map was taken from orbit by the camera on NASA's Mars Global Surveyor.
Voir l'image PIA05229: Reconstructing the Scene of Landing sur le site de la NASA.PIA05710: Lava Tubes of Olympus
5 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows evidence of two collapsed lava tubes on the southeast flank of the giant martian volcano, Olympus Mons. One runs diagonally across the entire image, the other is shorter and does not extend across the whole image. The shorter one is a series of pits and troughs, rather than a continuous channel. Lava flowed in tubes under the surface; later, the roof of each tube collapsed to form a series of pits and troughs which, in the larger example, eventually coalesced to its present, channel-like form. The image is located near 16.8°N, 132.2°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05710: Lava Tubes of Olympus sur le site de la NASA.PIA05255: Layered Remnant
28 January 2004
This southern summer Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a remnant of layered sedimentary material that was once much more extensive, covering a vast intercrater area near 69.1°S, 207.5°W. These layers have been protected from being completely removed by erosion, in part, because of the ancient meteor impact crater located at the lower left. The dark lines that squiggle and streak across this scene were most likely formed by passing dust devils that disrupted or removed some of the thin layer of dust coating this terrain. The picture covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05255: Layered Remnant sur le site de la NASA.PIA04867: Ius Chasma Layers
MGS MOC Release No. MOC2-542, 12 November 2003
Outcrops of layered rock abound in the "grand canyon of Mars," the Valles Marineris. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides an example from the upper northeast wall of Ius Chasma. This picture is located near 7.7°S, 76.1°W. The picture is 3 km (1.9 mi) wide and illuminated by sunlight from the lower right.
Voir l'image PIA04867: Ius Chasma Layers sur le site de la NASA.PIA05697: Crater in Utopia
23 March 2004
Craters of the martian northern plains tend to be somewhat shallow because material has filled them in. Their ejecta blankets, too, are often covered by younger materials. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example--a crater in Utopia Planitia near 43.7°N, 227.3°W. Erosion has roughened some of the surfaces of the material that filled the crater and covered its ejecta deposit. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05697: Crater in Utopia sur le site de la NASA.PIA04815: Crater in Syrtis Major
MGS MOC Release No. MOC2-527, 28 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a meteor impact crater in central Syrtis Major. This is a relatively young crater; its ejecta patterns are very well preserved and have not been eroded away by wind or buried by fine sediment. The crater is located near 8.5°N, 295.2°W. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left/upper left.
Voir l'image PIA04815: Crater in Syrtis Major sur le site de la NASA.PIA04685: South Polar Mesas
MGS MOC Release No. MOC2-451, 13 August 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of small mesas with sharp, arcuate edges located on the south polar residual cap of Mars. These mesas, each about 2 meters (6-7 feet) high, are all remnants of a single layer or grouping of layers of frozen carbon dioxide. Sublimation of the carbon dioxide has eroded the layer(s) from these flat-topped mesas. This scene is located near 86.6°S, 105.4°W and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04685: South Polar Mesas sur le site de la NASA.PIA04654: North Mid-latitude Crater
MGS MOC Release No. MOC2-427, 20 July 2003
Craters in the middle latitudes of Mars often have strangely-textured floors. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of a crater near 40.2°N, 184.5°W provides an example. The original crater has been somewhat eroded and much of its interior has been filled with sediment since it formed. The origin of the strange texture is unknown; speculations about most mid-latitude textures tend to focus on the idea that, somehow, subliming ground ice may have been involved. The texture on the floor of the crater is similar to, but not quite the same as, the texture on the nearby surfaces to the north and south of the crater. This picture covers an area 1.4 km (0.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04654: North Mid-latitude Crater sur le site de la NASA.PIA05014: Windblown Sand in West Candor
23 December 2003
West Candor Chasma, a part of the vast Valles Marineris trough system, is known for its layered sedimentary rock outcrops. It is less known for dark fields of windblown sand, but that is what occurs in the north-central part of the chasm. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, obtained in December 2003, shows the interplay of dark, wind-blown sand with buttes and mesas of layered rock in west Candor Chasma. Dark streamers of sand point toward the east/southeast (right/lower right), indicating that dominant winds blow from the west. This picture is located near 5.2°S, 75.7°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05014: Windblown Sand in West Candor sur le site de la NASA.PIA05807: Daedalia Streak
26 April 2004
This April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark wind streak on the lee (downwind) side of a small meteor impact crater in western Daedalia Planum. The substrate in this region consists of large lava flows (larger than the image shown here). The winds responsible for the streak came from the east/northeast (right). This picture is located near 15.4°S, 138.1°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05807: Daedalia Streak sur le site de la NASA.PIA04682: Scamander Vallis
MGS MOC Release No. MOC2-448, 10 August 2003
The heavily cratered terrains of Mars bear the scars of many, ancient valley systems and networks. When these were first seen in images from Mariner 9 more than 30 years ago, most investigators working on the topic concluded that the valleys must have formed by running water. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a somewhat meandered portion of Scamander Vallis, located in central Arabia Terra near 16.9°N, 331.5°W. The valley today is quite dry and the entire area--valley, craters, and surrounding terrain--are covered by an almost uniform blanket of dust. Dark streaks on the slopes are formed by small avalanches of dust. Sunlight illuminates the scene from the right.
Voir l'image PIA04682: Scamander Vallis sur le site de la NASA.PIA05013: Northern Plains Buried Craters
22 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows three circular features on the martian northern plains near 70.7°N, 311.7°W. These circular features are the locations of meteor impact craters that have been buried beneath the plains. Much of the northern plains shares this story, in which thousands of old craters have been filled or partially filled and then thinly buried beneath textured plains. The picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05013: Northern Plains Buried Craters sur le site de la NASA.PIA04653: Spiders from Mars?
MGS MOC Release No. MOC2-426, 19 July 2003
No, this is not a picture of a giant, martian spider web. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of polygonal features on the floor of a northern hemisphere impact crater near 65.6°N, 327.7°W. The picture was acquired during spring, after the seasonal carbon dioxide frost cap had largely migrated through the region. At the time the picture was taken, remnants of seasonal frost remained on the crater rim and on the edges of the troughs that bound each of the polygons. Frost often provides a helpful hint as to where polygons and patterned ground occur. The polygons, if they were on Earth, would indicate the presence of freeze-thaw cycles in ground ice. Although uncertain, the same might be true of Mars. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04653: Spiders from Mars? sur le site de la NASA.
PIA05690: Winter Clouds Over Mie
12 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows late winter clouds over the 104 km (~65 mi) diameter crater, Mie. Cellular clouds occur in the lower martian atmosphere, surrounding Mie Crater. Their cloudtops are at an altitude that is below the crater rim. Higher than the crater rim occurs a series of lee wave clouds, indicating air circulation moving from west/northwest (left) toward the east/southeast (right). Mie Crater is located in Utopia Planitia, not too far from the Viking 2 landing site, near 48.5°N, 220.4°W. Sunlight illuminates this January 2004 scene from the lower left.
Voir l'image PIA05690: Winter Clouds Over Mie sur le site de la NASA.PIA04812: Olympus Mons Lava Flows
MGS MOC Release No. MOC2-525, 26 October 2003
This May 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows lava flows on the lower northern flanks of the large martian volcano, Olympus Mons. Located near 21.9°N, 132.9°W, the image features flows that moved down the north slope, toward the north/northeast (top/upper right). Sunlight illuminates this scene from the left/lower left; the picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA04812: Olympus Mons Lava Flows sur le site de la NASA.PIA05641: Terby's Layered Rocks
14 March 2004
Layered rock outcrops are common all across Mars, and the Mars rover, Opportunity, has recently investigated some layered rocks in Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rocks in northern Terby Crater, located just north of the giant Hellas Basin near 27.5°S, 285.8°W. Hundreds of layers are exposed in a deposit several kilometers thick within Terby. A history of events that shaped the northern Hellas region is recorded in these rocks, just waiting for a person or robot to investigate. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.
Voir l'image PIA05641: Terby's Layered Rocks sur le site de la NASA.PIA04693: Daedalia Planum Wind Streaks
MGS MOC Release No. MOC2-459, 21 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle (red camera) image shows streaks in the lee of obstacles such as meteor impact craters and lava flow margins in southwestern Daedalia Planum. The image covers an area about 252 km (157 mi) across near 13°S, 142°W. The streaks indicate that the dominant winds blow toward the northwest (left/upper left). Sunlight illuminates the scene from the left/upper left.
Voir l'image PIA04693: Daedalia Planum Wind Streaks sur le site de la NASA.PIA05708: East Candor Layers
3 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dust-mantled layer exposures (left) in east Candor Chasma, one of the troughs of the Valles Marineris system. Erosion of the steeper slope (right) has disrupted the expression of layered material, indicating that some layered materials on Mars may not be recognized as such, depending upon how the materials have been degraded. This image is located near 7.8°S, 65.6°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.
Voir l'image PIA05708: East Candor Layers sur le site de la NASA.PIA05126: Dust Devils Near Schiaparelli
9 January 2004
The four arrows in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image point to active dust devils captured around 2 p.m. local time on a flat plain west of the large basin, Schiaparelli. This image is located near 5.1°S, 348.9°W; and covers an area 3 km (1.9 mi) wide. The dust devil shadows point toward the northeast (upper right) because sunlight illuminates the scene from the southwest (lower left).
Voir l'image PIA05126: Dust Devils Near Schiaparelli sur le site de la NASA.PIA04766: Pits and Layers
MGS MOC Release No. MOC2-496, 27 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in February 2003, shows pits formed by faulting and collapse in the Tractus Fossae region of Mars. The faulting and pitting processes have exposed the layered bedrock. Boulders, many of them now mantled by dust, have rolled down to the bottom of the larger pit. Dark streaks on the pit walls result from avalanches of dust. This picture is located near 23.7°N, 104.0°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
Voir l'image PIA04766: Pits and Layers sur le site de la NASA.PIA04639: South Polar "Poodle"
MGS MOC Release No. MOC2-422, 15 July 2003
Have you ever stared up at the clouds in the sky and seen the shapes of animals, people, or objects? Sometimes when the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) team is looking at newly-returned pictures from Mars, the same thing happens. This is a picture of pits and scarps in the frozen south polar carbon dioxide ice cap. Sunlight illuminates the scene from the upper right. At the bottom of the picture is a feature that resembles a long, thin poodle; its head faces to the left, the tail to the right. This picture is located near 86.9°S, 55.8°W.
Voir l'image PIA04639: South Polar "Poodle" sur le site de la NASA.
PIA04804: Chasma Boreale Dunes
MGS MOC Release No. MOC2-517, 18 October 2003
Frost covers dark sand dunes in this springtime view from Chasma Boreale in the martian north polar region. Dark spots indicate areas where the cold, carbon dioxide frost has begun to sublime away. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is located near 84.7°N, 359.3°W and covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the lower left.
Voir l'image PIA04804: Chasma Boreale Dunes sur le site de la NASA.PIA04761: Dusty Troughs
MGS MOC Release No. MOC2-494, 25 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows dust-mantled troughs formed by faulting on the plains northeast of the volcano, Ascraeus Mons. The smooth areas are covered with thick accumulations of dust, the rougher surfaces are lava flows that also have been blanketed by dust. Thick accumulations of dust are common throughout the Tharsis volcanic region of Mars. This picture is located near 8.3°N, 117.5°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04761: Dusty Troughs sur le site de la NASA.PIA05121: Locating Landers on Mars
4 January 2004
In 2003, a new technique was pioneered by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) experiment to allow the camera to obtain images with better than 1 meter (~ 3 ft) per pixel resolution. By pitching the spacecraft at a rate faster than the spacecraft moves in its orbit around Mars, MOC is able to obtain pictures with a down-track resolution of about 50 cm/pixel (~20 inches/pixel), although the cross-track resolution remains ~1.5 m/pixel (5 ft/pixel). One of the key goals of this image motion compensation (IMC) technique is to be able to image landers, such as the Mars Exploration Rovers, Spirit and Opportunity, on the martian surface. The two pictures shown here were acquired during the IMC testing in 2003. The first shows the location of the Mars Pathfinder lander (MPF) and the nearby boulder, Yogi. The second image shows the location of the Viking 1 (VL-1) lander. These locations were determined by using sight lines from the landers to near and far objects seen in the pictures acquired by the landers, and then matching these to locations in earlier, 1.5 to 3.0 m/pixel MOC images. Then, the IMC images, shown here, were acquired by MGS so that the actual landers, sitting on the martian surface, might be resolved. This technique only works well when the location of the lander is already fairly-well established. It would be extremely difficult to find a lander for which the location is uncertain, such as Viking 2 or Mars Polar Lander (in fact, for Mars Polar Lander, it would take over 60 years to map out the entire landing ellipse in which the spacecraft was lost). The two images shown here are illuminated from the left and show areas only a few hundred meters across.
More information about how MGS MOC will be used to help locate the Mars Exploration Rovers, Spirit and Opportunity, can be found by visiting:
Finding MERs.
Voir l'image PIA05121: Locating Landers on Mars sur le site de la NASA.PIA04920: Layers in Tithonium
MGS MOC Release No. MOC2-570, 10 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows eroded layered bedrock outcrops in the upper walls of one of the depressions in the Tithonium Chasma trough system. Tithonium Chasma is one of the canyons of the Valles Marineris, a vast gouge that--if it occurred on Earth-would span the distance from Los Angeles, California, to New York City. The Valles Marineris canyons were not carved by running water, instead they formed mostly by the combined forces of faulting and mass movement (landslides) as gravity eroded materials from the walls. This image is located near 4.2°S, 85.1°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04920: Layers in Tithonium sur le site de la NASA.PIA04694: Banded Terrain in East Hellas
MGS MOC Release No. MOC2-460, 22 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle camera image shows banded terrain in easternmost Hellas Planitia, between the distal ends of Dao and Harmakhis valleys. These bands probably indicate the location of eroded, layered bedrock that has been covered by a mantling deposit that, itself, became eroded to form the very small pits and bumps that pervade the region. This picture is located near 41.1°S, 275.0°W. Sunlight illuminates the scene from the left/upper left.
Voir l'image PIA04694: Banded Terrain in East Hellas sur le site de la NASA.PIA05701: South Polar Layers
27 March 2004
This 1.5 meter per pixel (5 ft./pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows south polar layers exposed on the slopes of a mesa near 74.2°S, 244.6°W. These layers were once more extensive across the region, today only this and a few other remnants remain. The dark streaks were created by spring and summer dust devils that swept across the layered mesa with little regard to the changes in topography. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05701: South Polar Layers sur le site de la NASA.PIA05244: Lyot Crater in Winter
19 January 2004
This somewhat oblique Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle view of Lyot Crater and the mesas of the Deuteronilus Mensae was acquired in January 2004 on the day after the Mars Exploration Rover, Spirit, landed in Gusev Crater on the other side of the planet. It is winter in the northern hemisphere of Mars, and winter for Lyot Crater means clouds. The brighter features in the atmosphere above the surface in this image are clouds. Lyot Crater is about 236 km (~147 mi.) in diameter. The center of this image is near 48.5°N, 331.0°W, and is illuminated from the lower left.
Voir l'image PIA05244: Lyot Crater in Winter sur le site de la NASA.PIA04876: Galle Crater Scene
MGS MOC Release No. MOC2-547, 17 November 2003
This November 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows gullies, sand dunes, and streaks formed by dust devils in southern Galle Crater. The gullies are seen in the upper left (northwest) corner; they originate at layered rock exposures on a hillslope, and meander downslope through a deposit of dark, windblown sand. The gullies might have formed by running water. All of the darker surfaces in this image are dunes; these dunes were covered with bright dust during the previous winter (it is now summer in the southern hemisphere of Mars). Dust devils have been darkening the dunes by removing or disrupting the coating of dust, leaving behind a chaotic plethora of darks streaks. The image is located near 51.9°S, 31.4°W. The area shown is about 3 km (1.9 mi) wide by 6.8 km (4.2 mi) high. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04876: Galle Crater Scene sur le site de la NASA.PIA05532: East Arabia Layers
6 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded layered material in eastern Arabia Terra. The darkest material in this image forms a couple of mesas of ancient layered rock. Eastern Arabia is one of several regions on Mars that have been eroded in such a way as to provide clues about the nature of the layered upper crust of Mars. The image is located near 25.0°N, 302.4°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05532: East Arabia Layers sur le site de la NASA.PIA05295: Opportunity Site: Before and After
13 February 2004
This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle images shows the landing site of the Mars Exploration Rover (MER-B), Opportunity, before and after the landing. The first image was acquired on 24 August 2003, five months prior to the 25 January 2004 landing. The second picture, obtained on 1 February 2004, shows the lander--located within a ~20 meter (~66 feet) diameter crater--and other features that resulted from the landing. The Opportunity landing site is located in Meridiani Planum near 2.0°S, 5.6°W. Both images are simple cylindrical map projections with north up and east to the right; the lower image is about 1.4 kilometers (0.9 miles) wide. The dark area on the right side of the upper picture was not imaged by MOC until after the landing. Sunlight illuminates each scene from the lower left.
Voir l'image PIA05295: Opportunity Site: Before and After sur le site de la NASA.PIA04929: Gullies in Crater in Hellas
MGS MOC Release No. MOC2-571, 11 December 2003
This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies cut into debris on the southeast-facing wall of an old meteor impact crater in southeastern Hellas Planitia. This view is located near 44.5°S, 277.0°W. The 200 meter scale bar is approximately 656 feet across; the picture is illuminated from the upper left.
Voir l'image PIA04929: Gullies in Crater in Hellas sur le site de la NASA.PIA05185: High-resolution View of Gullies
12 January 2004
One goal of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) extended mission is to examine middle- and polar-latitude gullies at the highest resolutions available to MOC. This image, at 1.5 meters (5 feet) per pixel, shows several gullies carved into the material covering the wall of an old meteor impact crater near 46.7°S, 162.3°W. Large boulders that have come down the slopes are present among the gullies and their aprons. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05185: High-resolution View of Gullies sur le site de la NASA.PIA05292: Stripped Crater Floor
10 February 2004
This full-resolution Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows details on the floor of an ancient meteor crater in the northeastern part of Noachis Terra. After the crater formed, layers of material--perhaps sediment--were deposited in the crater. These materials became somewhat solidified, but later were eroded to form the patterns shown here. Many windblown ripples in the scene indicate the presence of coarse-grained sediment that was not completely stripped away by wind. The picture is located near 22.1°S, 307.0°W. Sunlight illuminates this scene from the left/upper left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05292: Stripped Crater Floor sur le site de la NASA.PIA05535: Schiaparelli's Wind Streaks
9 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows craters and dark wind streaks on a plain on the floor of northeastern Schiaparelli Basin. The streaks indicate that dominant winds blow from the northeast (upper right). The image is located near 1.5°S, 339.8°W. Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05535: Schiaparelli's Wind Streaks sur le site de la NASA.PIA05706: South Polar Dunes
1 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small patch of dark, windblown sand in the martian south polar region. Throughout the south high latitudes, dark sand has been trapped by wind in craters, pits, and depressions. This example is located near 64.5°S, 9.5°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05706: South Polar Dunes sur le site de la NASA.PIA04768: Small Syrian Volcano
MGS MOC Release No. MOC2-498, 29 September 2003
Today, 29 September 2003, is the first day of southern summer, and the first day of northern winter on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small volcano in Syria Planum near 12.9°S, 102.7°W. The volcano and surrounding terrain have been thickly mantled by dust; this dust has subsequently been eroded so that it appears textured rather than smooth. The thin, light streaks that crisscross the image are the tracks left by passing dust devils. Not all dust devils on Mars make streaks, and not all streaks are darker than their surroundings--those found in Syria Planum are invariably lighter in tone. The picture covers an area 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
Voir l'image PIA04768: Small Syrian Volcano sur le site de la NASA.PIA05128: Cratered Hill in Amazonis
11 January 2004
Looking somewhat like a martian moon that has been plunked down into a rough-textured but otherwise flat plain, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an old, cratered hill was once part of the rim of a meteor impact crater. The crater has been both eroded away and partly filled and buried beneath the rugged plains. The hill is interpreted to be considerably older than the plains, because it has considerably more small meteor craters than the surrounding terrain. This hill is located near 23.0°N, 166.5°W. The image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA05128: Cratered Hill in Amazonis sur le site de la NASA.PIA05458: Boulder Tracks
27 February 2004
On some fine-grained martian slopes, rolling boulders make tracks. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of boulder tracks on a crater wall near 35.8°S, 158.5°W. Sunlight illuminates the scene from the upper right; the 150 m scale bar is also about 492 feet long.
Voir l'image PIA05458: Boulder Tracks sur le site de la NASA.PIA04679: Layers in Tithonium Chasma
MGS MOC Release No. MOC2-445, 7 August 2003
Tithonium Chasma is one of the troughs of the vast Valles Marineris canyon system. Within many of these troughs are outcrops of light-toned, layered, sedimentary rock. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded sedimentary rock exposures overlain by the remnants of a smoother-surfaced, dark material. The dark feature is a younger sedimentary deposit made of a different material than the light-toned sediments; it covered the lighter rocks after they were eroded to their present form. This area is located near 5.0°S, 89.8°W. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04679: Layers in Tithonium Chasma sur le site de la NASA.PIA04721: Ancient Sedimentary Rocks
MGS MOC Release No. MOC2-469, 31 August 2003
The terraced area in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an outcropping of ancient, sedimentary rock. It occurs in a crater in western Arabia Terra near 10.8°N, 4.5°W. Sedimentary rocks provide a record of past environments on Mars. Field work will likely be required to begin to get a good understanding of the nature of the record these rocks contain. Their generally uniform thickness and repeated character suggests that deposition of fine sediment in this crater was episodic, if not cyclic. These rocks might be indicators of an ancient lake, or they might have been deposited from grains settling out of an earlier, thicker, martian atmosphere. This image covers an area 3 km (1.9 mi) across and is illuminated from the lower left.
Voir l'image PIA04721: Ancient Sedimentary Rocks sur le site de la NASA.PIA04844: Olympica Fossae
MGS MOC Release No. MOC2-534, 4 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a picturesque view of terrain in the Olympica Fossae region of Mars. This valley system is known for having a complex array of landforms thought to have been carved by water, cut by faulting, and covered by lava flows and windblown dust. The view shown here includes a look at some of the layered bedrock exposed by the forces that created the valley. The dark dots on the floors of the valleys are large boulders that have rolled down the slopes. Much of this scene has been mantled by fine, bright dust; dark streaks on the slopes indicate places where some of this dust has slid. This picture is located near 24.5°N, 115.9°W. The image covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA04844: Olympica Fossae sur le site de la NASA.PIA05856: Frosty Dune Field
1 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows frost-covered sand dunes in the early northern spring of 2004 in the north polar region. Sunlight illuminates the dunes from the bottom/lower left, but frost on slopes facing the lower right create the illusion of sunlight from that direction. This dune field, which would appear quite dark in summertime, is located near 80.3°N, 148.7°W. The picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05856: Frosty Dune Field sur le site de la NASA.PIA04838: Isidis Planitia
MGS MOC Release No. MOC2-530, 31 October 2003
Isidis Planitia is a vast, nearly circular plain centered at 12°N, 273°W. Its circular shape has led Mars researchers to suspect that it is the site of a very ancient, very eroded basin formed by asteroid or comet impact when the planet was still very young. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 3 km (1.9 mi) wide view of a typical Isidis Planitia scene. All over Isidis Planitia are found craters, ripple-like, light-toned, windblown dunes, and rugged mounds with summit pits. The mounds with summit pits might mark the location of impact craters that formed in a layer of material that used to cover much of Isidis Planitia, but has been largely stripped away, leaving the floors of former impact craters standing high upon remnants of this formerly more extensive layer. This example is located near 18.2°N, 272.5°W, and is illuminated by sunlight from the lower left.
Voir l'image PIA04838: Isidis Planitia sur le site de la NASA.PIA05748: North Polar Dunes
14 April 2004
The north polar cap of Mars is nearly surrounded by fields of dark sand dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the north polar dunes as they appeared in late winter in January 2004. At the time, the dunes were covered with frost. The image is located near 77.8°N, 52.8°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05748: North Polar Dunes sur le site de la NASA.PIA04726: South Polar Polygons
MGS MOC Release No. MOC2-473, 4 September 2003
Looking somewhat like the roadmap of a city on Earth, this August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows patterned ground--a mosaic of polygonal forms--highlighted by seasonal frost in the south polar region near 86.3°S, 310.2°W. Dark surfaces in this springtime view are areas from which cold, carbon dioxide frost has been subliming away. The picture covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04726: South Polar Polygons sur le site de la NASA.PIA04843: Tharsis Wind Streaks
MGS MOC Release No. MOC2-533, 3 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows dark wind streaks on a plain east of Olympus Mons in the Tharsis region of Mars. Streaks such as these change from time to time over the course of a martian year, suggesting that they are the result of wind movement of a thin layer of bright dust. In other words, wind is not moving dark material to make the dark streaks, it is removing bright material (thin coatings of dust). This picture is located near 16.3°N, 127.7°W. The image covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04843: Tharsis Wind Streaks sur le site de la NASA.PIA04785: East Candor Layers
MGS MOC Release No. MOC2-507, 8 October 2003
The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) experiment was designed to study the geology and geomorphology of Mars by providing images comparable in resolution to the aerial photographs used by terrestrial geologists in conducting their field work. For over six years, the MOC narrow angle camera has been returning pictures that underscore, time and again, the layered nature of the upper martian crust. It is from layered rock that geologists will one day be able to decipher the history of the red planet. This example of layered rock exposures occurs in eastern Candor Chasma, one of the troughs of the Valles Marineris system. The picture is located near 8.0°S, 67.0°W, and covers an area 3 km (1.9 mi) wide. The image is illuminated by sunlight from the lower left.
Voir l'image PIA04785: East Candor Layers sur le site de la NASA.PIA04915: Troughs in Tempe Terra
MGS MOC Release No. MOC2-570, 10 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows troughs created by movement along geologic faults in the upper crust of Mars in the Tempe Terra region. Large ripple-like dunes have formed in sediment trapped on the floors of the troughs. In most cases, the ripples are oriented with their crests perpendicular to the troughs, indicating that local winds within each trough are responsible for their patterns. This area is located near 33.1°N, 70.2°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04915: Troughs in Tempe Terra sur le site de la NASA.PIA04670: South Polar Scarps
MGS MOC Release No. MOC2-438, 31 July 2003
The terrain of the south polar residual ice cap, made up mostly of frozen carbon dioxide, has come to be known by many as "swiss cheese terrain," because many areas of the cap resemble slices of swiss cheese. However, not all of the south polar cap looks like a tasty lunch food. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a series of curving scarps formed by erosion and sublimation of carbon dioxide from the south polar cap. This area is located near 86.3°S, 51.2°W. The image is illuminated by sunlight from the upper left; the area is about 1.5 km (0.9 mi) wide.
Voir l'image PIA04670: South Polar Scarps sur le site de la NASA.PIA05741: Springtime Dunes, 2004
12 April 2004
Today is April 12, 2004, the 43rd anniversary of the first human flight into space (Yuri Gagarin, 1961) and the 23rd anniversary of the first NASA Space Shuttle flight (Columbia, 1981). Meanwhile, on Mars, spring is in full swing in the martian northern hemisphere. With spring comes the annual defrosting of the north polar dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired on April 7, 2004, shows a field of small barchan (crescent-shaped) dunes covered with the remains of wintertime frost. The dark spots around the base of each dune mark the first signs of the spring thaw. The sand in these dunes is dark, like the black sand beaches of Hawaii or the dark, sandy soil of the rover, Opportunity, landing site, but in winter and spring their dark tone is obscured by bright carbon dioxide frost. This picture is located near 75.9°N, 45.3°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05741: Springtime Dunes, 2004 sur le site de la NASA.PIA05320: Yardangs in Gordii Dorsum Region
19 February 2004
Yardangs are wind erosion features shaped somewhat like inverted boat hulls. Yardangs are common on Mars, as wind is the most erosive agent acting today on this desert planet. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located in the vicinity of the Gordii Dorsum near 4.2°S, 159.9°W. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05320: Yardangs in Gordii Dorsum Region sur le site de la NASA.PIA04912: Crater in Marte Vallis
MGS MOC Release No. MOC2-566, 6 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a streamlined tail-pointing toward the upper right (northeast)--in the lee of a meteor impact crater in Marte Vallis, a large valley and channel complex southeast and east of the Elysium volcanic region. The fluid that went through Marte Vallis, whether water, mud, lava, or otherwise, created this form as it moved from the lower left (southwest) toward the upper right. The crater is located near 19.0°N, 174.9°W. The image covers an area 3 km (1.9 mi) wide and is illuminated from the left.
Voir l'image PIA04912: Crater in Marte Vallis sur le site de la NASA.PIA05790: Collapsed Subsurface Channel
16 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows evidence of a collapsed lava tube (or other form of subterranean channel)on the plains northwest of the Elysium volcanoes. Lava or another fluid (e.g., water) was transported through a subsurface channel; later, the roof collapsed to form a series of pits and troughs, revealing the channel's location. This landform is located near 32.7°N, 219.5°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05790: Collapsed Subsurface Channel sur le site de la NASA.PIA04677: Aeolis Yardangs
MGS MOC Release No. MOC2-443, 5 August 2003
Yardangs are ridges formed by wind erosion. The classic, "textbook" examples of yardangs are those that appear to be like the inverted hull of a boat. They most commonly form in sedimentary rock or volcanic ash deposits that contain some proportion of sand-sized grains. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows yardangs in the Aeolis region of Mars. Their tapered ends point toward the upper left, indicating the dominant winds responsible for their erosion came from the lower right. This picture is located near 1.0°N, 214.4°W. It is illuminated by sunlight from the lower left.
Voir l'image PIA04677: Aeolis Yardangs sur le site de la NASA.PIA05858: Alcoves in a Xanthe Crater
3 May 2004
Martian middle- and polar-latitude gullies are not the only places that 'alcoves' form by downslope erosion of debris. Even at equatorial latitudes, some craters exhibit these features. Alcoves at the heads of narrow, dry landslide scars are indicated in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of a crater wall in Xanthe Terra. In both the middle/polar-latitude gully cases and in this example, alcoves form by undermining and collapse of material high on a relatively steep slope such as a crater wall. In this case, however, no fluid was involved, thus no gully or distinct apron formed. This crater wall is located near Shalbatana Vallis around 2.7°N, 43.1°W. The image is illuminated from the left; the 400 meter scale bar is about 437 yards long. For comparison, an example of martian gullies with alcoves, channels, and aprons can be seen in: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies, 22 June 2000; see PIA01031.
Voir l'image PIA05858: Alcoves in a Xanthe Crater sur le site de la NASA.PIA04782: Valley Near Nilus Chaos
MGS MOC Release No. MOC2-504, 5 October 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a valley near Nilus Chaos, around 25.2°N, 80.3°W. The scene has a uniform albedo, indicating that all of the landforms are probably mantled by fine, bright dust. Dark streaks on the valley walls indicate places where recent dust avalanches have occurred. The ripple-like dune features on the valley floor were formed by wind, but today they are inactive and covered with dust. A few craters, created by impacting debris, have formed on the dunes, again attesting to their inactivity in the modern martian environment. The image covers an area 3 km (1.9 mi) wide; it is illuminated by sunlight from the lower left.
Voir l'image PIA04782: Valley Near Nilus Chaos sur le site de la NASA.PIA04836: Chasma Australe Fog
MGS MOC Release No. MOC2-528, 29 October 2003
Fog is a common occurrence in some areas of the retreating south polar seasonal frost cap. Fogs are commonly banked-up against steep slopes or found inside defrosting craters. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captured mid-afternoon fog banked against the layered walls of Chasma Australe, a trough in the south polar region of Mars. The frost-covered layers of Chasma Australe can be seen on the right side of this image, the billowy fog is to the left. Sunlight illuminates this scene from the upper left. The fog, probably composed of water ice crystals, casts shadows on the chasm wall. This picture is located near 83.5°S, 257.9°W, and covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04836: Chasma Australe Fog sur le site de la NASA.PIA04683: Bouldery Surface
MGS MOC Release No. MOC2-449, 11 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image shows part of the boulder-strewn surface of an ejecta deposit from a meteor impact crater in Noachis Terra at 49.7°S, 341.6°W. The impact process ejects bouldery debris from the crater and deposits it all around the outside of the crater. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04683: Bouldery Surface sur le site de la NASA.PIA05012: Raising Dust
21 December 2003
Dust storms are a common occurrence on the extremely arid planet, Mars. However, very rarely do we get to see the actual process of dust being lifted off the martian surface to feed these dust storms. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures some of the dust-raising process in action. The picture shows a shallow trough with large, ripple-like dunes on its floor. Sunlight illuminates the scene from the upper left. Puffy, billowy clouds of dust obscure some of the surface from view. Closer inspection shows streamers of dust, streaking from left/upper left toward right/lower right, down near the surface of the planet. It is in these streamers that dust is being lifted from the ground. This image is located near 29.6°S, 73.1°W, and covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05012: Raising Dust sur le site de la NASA.PIA05691: Dark Slope Streaks
13 March 2004
Martian slope streaks occur in the regions most heavily mantled by fine, dry dust, particularly Tharsis, Arabia, and the knobby areas between Amazonis and Cerberus. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some examples of dark slope streaks off of buttes, mesas, and massifs in a dust-mantled crater in central Arabia Terra. New slope streaks form from time to time in the modern martian environment; the streaks in this image probably formed within the past decade. To create them, dust slid or avalanched down the slopes in an almost liquid-like manner. The image is located near 6.8°N, 321.7°W. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05691: Dark Slope Streaks sur le site de la NASA.PIA04776: Small Impact Crater
MGS MOC Release No. MOC2-502, 3 October 2003
This May 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides a high resolution view (1.5 meters--5 feet--per pixel) of a small meteor crater near 28.0°N, 182.8°W. This crater is about 300 m (~980 feet) across, just under one-third the size of the famous Meteor Crater in northern Arizona, U.S.A. Boulders ejected by the impact dot the scene. Sunlight illuminates the crater from the lower left.
Voir l'image PIA04776: Small Impact Crater sur le site de la NASA.PIA04813: Hecates Tholus
MGS MOC Release No. MOC2-526, 27 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows Hecates Tholus, the northernmost of the three large Elysium volcanoes. The non-circular pit just southwest (toward lower left) of the center of this view is the summit caldera, a complex depression formed by collapse. This volcano has several large impact craters on its surface, indicating that it is a relatively old landform. None of the martian volcanoes are thought to be active today, and none of the MOC images of the martian volcanoes obtained thus far give any indication to the contrary. Hecates Tholus is located at 32°N, 210°W. This picture is illuminated by sunlight from the lower left and covers an area about 170 km (~105 mi) across.
Voir l'image PIA04813: Hecates Tholus sur le site de la NASA.PIA04771: Hellas "Taffy Pull"
MGS MOC Release No. MOC2-499a, 30 September 2003
Some of the strangest-looking surfaces on Mars occur in northwestern Hellas Planitia. Over the years, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) team has informally--quite informally--taken to calling these surfaces, "taffy-pull terrain." This image shows an example located near 39.2°S, 305.2°W. The origin of this pattern is unknown, although it is thought to be related to the erosion of different layers of bedrock or substrate of differing physical properties. That is, a hard layer would be more difficult to erode than a soft, or poorly-consolidated layer. However, layering and erosion alone probably do not explain these landforms; perhaps faulting or mass movement of debris also involved. As with all other explorations in our Solar System, sometimes the pictures we get back from space present us with more questions, rather than answers. This image covers an area 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
Voir l'image PIA04771: Hellas "Taffy Pull" sur le site de la NASA.PIA05696: Lycus Sulci Slope Streaks
21 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark slope streaks on ridges in the Lycus Sulci region, north of the Olympus Mons volcano. Slope streaks form in the dry, dust-mantled regions of Mars. The darker streaks formed more recently than lighter ones, perhaps within the past Mars year or two. These streaks are located near 24.1°N, 146.1°W. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05696: Lycus Sulci Slope Streaks sur le site de la NASA.PIA04930: Clouds Near Mie Crater
MGS MOC Release No. MOC2-572, 12 December 2003
Mie Crater, a large basin formed by asteroid or comet impact in Utopia Planitia, lies at the center of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image. The crater is approximately 104 km (65 mi) across. To the east and southeast (toward the lower right) of Mie, in this 5 December 2003 view, are clouds of dust and water ice kicked up by local dust storm activity. It is mid-winter in the northern hemisphere of Mars, a time when passing storms are common on the northern plains of the red planet. Sunlight illuminates this image from the lower left; Mie Crater is located at 48.5°N, 220.3°W. Viking 2 landed west/southwest of Mie Crater, off the left edge of this image, in September 1976.
Voir l'image PIA04930: Clouds Near Mie Crater sur le site de la NASA.PIA05763: Mesa in Granicus Valles
15 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a mesa left standing when erosion created the Granicus Valles system, located west of the Elysium volcanoes near 27.8°N, 224.3°W. Dark dots at the base of the mesa's slopes and on the valley floor are large boulders. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05763: Mesa in Granicus Valles sur le site de la NASA.PIA04684: Peridier Crater
MGS MOC Release No. MOC2-450, 12 August 2003
The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red instrument captured this autumn view of Peridier Crater on August 6, 2003. The crater is about 100 km (62 mi.) in diameter and located at 25.7°N, 276.2°W. It was named for French astronomer Julien Peridier (1882-1967). In this Mercator map-projected view, north is up and east is to the right. The dark feature on the southwest floor of the crater is known from high resolution MOC images to be a field of windblown dunes. Finer, dark-toned sediment has been blown out of the dune field and settled on the crater rim and just outside the crater to the southwest. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04684: Peridier Crater sur le site de la NASA.PIA04655: Polygons in Martian Frost
MGS MOC Release No. MOC2-428, 21 July 2003
This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a polygonal pattern developed in seasonal carbon dioxide frost in the martian southern hemisphere. The frost accumulated during the recent southern winter; it is now spring, and the carbon dioxide frost is subliming away. This image is located near 80.4°S, 200.2°W; it is illuminated by sunlight from the upper left, and covers an area 3 km (1.9 mi) across.
Voir l'image PIA04655: Polygons in Martian Frost sur le site de la NASA.PIA05806: Columbus Wall Outcrop
25 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, somewhat layered rock outcrops on the north wall of Columbus Crater, located near 28.7°S, 166.3°W. This material is a remnant of a formerly more extensive light-toned unit that extended across the floor of Columbus. Today, remnants are found all around the walls of the crater, and at least one small remnant has been spotted on the crater floor. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05806: Columbus Wall Outcrop sur le site de la NASA.PIA05698: Cerberus Fossae Trough
24 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides a look down into one of the long, dark, Cerberus Fossae troughs near 10.2°N, 202.6°W. Faulting and extension of the upper martian crust in this region has caused numerous troughs such as this to form. The trough walls expose layered bedrock that serves as a source for dark-toned debris that creates talus deposits. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05698: Cerberus Fossae Trough sur le site de la NASA.PIA05711: Gullies in Crater Wall
6 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies in the wall of a large impact crater in Newton Basin near 41.9°S, 158.1°W. Such gullies may have formed by downslope movement of wet debris--i.e., water. Unfortunately, because the responsible fluid (if there was one) is no longer present today, only the geomorphology of the channels and debris aprons can be used to deduce that water might have been involved. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05711: Gullies in Crater Wall sur le site de la NASA.PIA05254: Sedimentary Rock Layers
27 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers of sedimentary rock in a crater in western Arabia Terra. Layered rock records the history of a place, but an orbiter image alone cannot tell the entire story. These materials record some past episodes of deposition of fine-grained material in an impact crater that is much larger than the image shown here. The picture is located near 3.4°N, 358.7°W, and covers an area 3 km (1.9 mi.) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05254: Sedimentary Rock Layers sur le site de la NASA.PIA05282: Polygons in Seasonal Frost
8 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime scene in the south polar region of the red planet. A patch of bright frost--possibly water ice--is seen in the lower third of the image. Polygon patterns that have developed in the ice as it sublimes away can be seen; these are not evident in the defrosted surfaces, so they are thought to have formed in the frost. This image is located near 82.6°S, 352.5°W. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05282: Polygons in Seasonal Frost sur le site de la NASA.PIA04861: Valley near Olympus
MGS MOC Release No. MOC2-539, 9 November 2003
A suite of channels and valleys are carved into the plains southeast of the martian volcano, Olympus Mons. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 16.5°N, 124.8°W. Whether the valley was cut by water is unknown. Today it is dry, has dust-covered wind ripples on the floor of the innermost channel, and small craters have formed here and there on the valley terrain. This picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.
Voir l'image PIA04861: Valley near Olympus sur le site de la NASA.PIA05253: Summer South Polar Cap
26 January 2004
This January 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows what the martian south polar residual cap looks like in the middle of summer. Sunlight illuminates the scene from the top/upper left. The picture shows mesas composed of frozen carbon dioxide, each about 2-5 meters (6-16 ft.) high. Sunlight has darkened the slopes around the mesas as carbon dioxide sublimes away throughout the summer. The image is located near 86.2°S, 351.4°W, and covers an area 3 km (1.9 mi.) wide.
Voir l'image PIA05253: Summer South Polar Cap sur le site de la NASA.PIA04669: Olympus Mons Lava Flows
MGS MOC Release No. MOC2-437, 30 July 2003
Olympus Mons is the largest volcano on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the lava flows on the middle south flank of the giant volcano. Illuminated from the lower right, this picture is located near 16.4°N, 135.5°W.
Voir l'image PIA04669: Olympus Mons Lava Flows sur le site de la NASA.PIA05846: Small, Bouldery Crater
30 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a relatively young impact crater located in southeastern Arabia Terra near 4.8°N, 313.9°W. It is about 1 kilometer (about six tenths of a mile) in diameter, roughly the size of the famous Meteor Crater in northern Arizona, U.S.A. Indeed, the Arizona crater may once have looked very similar to this, but erosion on Earth has been more vigorous than on the modern Mars. Large boulders, many of them bigger than a typical house, can be seen in the ejecta blanket and on the crater floor. Fine, bright dust, common throughout Arabia Terra, has thinly mantled all but the steepest slopes. The image is illuminated by sunlight from the left/upper left. The picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05846: Small, Bouldery Crater sur le site de la NASA.PIA05342: Wind Streak and Crater
23 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak developed in the lee of a meteor impact crater in western Daedalia Planum. The dominant winds responsible for the streak blew from the bottom/lower right (southeast). The image is located near 9.9°S, 144.9°W. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05342: Wind Streak and Crater sur le site de la NASA.PIA05919: Ares Vallis Dust Devil
12 May 2004
When it was operating in the Ares/Tiu Valles region of Chryse Planitia, Mars, in 1997, Mars Pathfinder detected dust devils that passed over and near the lander. From orbit, no images of dust devils at the Mars Pathfinder site have yet been acquired, but this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime dust devil near the rim of a 610-meter (~670 yards)-diameter impact crater in the same general region as the Mars Pathfinder site. This scene is near 19.6°N, 32.9°W, in part of the Ares Vallis system. The dust devil in this case is not making a streak, as dust devils tend to do in some regions of Mars. The dark feature to the right (east) of the dust devil is its shadow. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/upper left.
Voir l'image PIA05919: Ares Vallis Dust Devil sur le site de la NASA.PIA04977: Old Martian Valley
MGS MOC Release No. MOC2-578, 18 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an ancient, unnamed, martian valley in the Xanthe Terra region, located near 3.3°S, 54.9°W. This valley might have been a conduit for flowing water, but there is no way to be certain because it is so old that none of its original features have been preserved. Bright, windblown ripples are now found on the valley floor. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the left.
Voir l'image PIA04977: Old Martian Valley sur le site de la NASA.PIA05261: Ripples in Tempe Mensa Region
1 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows large windblown ripples (or, some might say, small dunes) in troughs between mesas of the Tempe Mensa region. The ripples are generally perpendicular to the trough walls, indicating that [missing text] the features blew through these canyons. The image is located near 33.5°N, 69.2°W. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05261: Ripples in Tempe Mensa Region sur le site de la NASA.PIA04882: Cracked South Polar Plain
MGS MOC Release No. MOC2-551, 21 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a complexly-cracked and eroded plain in the south polar region of Mars. This image was acquired just a few weeks ago, in late October 2003; as such, the processes that formed the nearly regular pattern of squiggly troughs and cracks are presently unknown. The image is located near 85.0°S, 100.8°W, and covers an area 3 km (1.9 mi) wide. The picture is illuminated by sunlight from the upper left.
Voir l'image PIA04882: Cracked South Polar Plain sur le site de la NASA.PIA04736: North Polar Dune Patterns
MGS MOC Release No. MOC2-478, 9 September 2003
Dark, windblown sand forms spectacular geometric patterns in the north polar sand seas, particularly in regions where strong winds converge from different directions over the course of a year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows some of these dark dune patterns near 77.8°N, 284.4°W. The picture covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA04736: North Polar Dune Patterns sur le site de la NASA.PIA04795: Northern Plains Patterns
MGS MOC Release No. MOC2-513, 14 October 2003
Patterns are common on the northern plains of Mars. Like their terrestrial counterparts in places like Siberia, Alaska, and northern Canada, patterned ground on Mars might be an indicator of the presence of ground ice. Whether it is true that the patterns on Mars are related to ground ice and whether the ice is still present beneath the martian surface are unknown. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example of patterned ground on the martian northern plains near 72.4°N, 252.6°W. The dark dots and lines are low mounds and chains of mounds. The circular feature near the center of the image is the location of a buried meteor impact crater; its presence today is marked only by the dark boulders on its rim and ejecta blanket that have managed to remain uncovered at the martian surface. The area shown is 3 km (1.9 mi) wide and illuminated by sunlight from the lower left.
Voir l'image PIA04795: Northern Plains Patterns sur le site de la NASA.PIA05917: Sedimentary Rocks of Aram Chaos
10 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcroppings of light-toned, layered, sedimentary rock within Aram Chaos, an ancient, partly-filled impact crater located near 3.2°N, 19.9°W. This 1.5 meters (5 feet) per pixel picture is illuminated by sunlight from the left and covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05917: Sedimentary Rocks of Aram Chaos sur le site de la NASA.PIA04744: Kasei Valles Scene
MGS MOC Release No. MOC2-483, 14 September 2003
This is a May 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture of terrain in the Kasei Valles region. The lower third of the image shows flow patterns formed by mud or lava from some of the youngest flow events that occurred in the valley system. These events occurred some time ago, however, because there has been sufficient time for a plethora of small impact craters to form on the surface. In addition, large, ripple-like, windblown bedforms occur along the margin of the flow materials and the adjacent upland. At least two generations of ripples are recognized--a suite of larger ones with groups of smaller ripples located between them. The image is located near 16.4°N, 74.9°W. This picture covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA04744: Kasei Valles Scene sur le site de la NASA.PIA04738: Layers in Gale Crater
MGS MOC Release No. MOC2-479, 10 September 2003
This is a red camera wide angle view of the giant martian volcano, Olympus Mons, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). The volcano is large enough to cover much of the U.S. state of New Mexico. This view was taken looking west toward the sunward limb of the planet. The limb is the horizon to the left; the dark band is outer space. Sunlight illuminates this scene from the lower left.
Voir l'image PIA04738: Layers in Gale Crater sur le site de la NASA.PIA04660: Fortune Cookie Sand Dunes
MGS MOC Release No. MOC2-432, 25 July 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of small barchan sand dunes in the north polar region near 71.7°N, 51.3°W. Some of them are shaped like fortune cookies. The message these dunes provide: winds blow through this region from the lower right toward the upper left. The steep slip face slopes of these dunes, which point toward the upper left, indicate the wind direction. The scene is illuminated by sunlight from the upper right. The image is 3 km (1.9 mi) wide.
Voir l'image PIA04660: Fortune Cookie Sand Dunes sur le site de la NASA.PIA05020: Gullies in Galle
25 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies carved into a slope in southern Galle Crater, east of Argyre Planitia. These may have been carved by a liquid such as water. The slopes are part of the inner ring of rocky mountains uplifted by the asteroid or comet impact that formed Galle Crater. The crater is extremely ancient; the gullies are much more recent landforms. The picture is located near 51.8°S, 31.2°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05020: Gullies in Galle sur le site de la NASA.PIA04905: Polygons near Lyot Crater
MGS MOC Release No. MOC2-564, 4 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows patterned ground, arranged in the form of polygons, on the undulating plains associated with ejecta from the Lyot impact crater on the martian northern plains. This picture was acquired in October 2003 and shows that the polygon margins are ridges with large boulders--shown here as dark dots--on them. On Earth, polygon patterns like this are created in arctic and antarctic regions where there is ice in the ground. The seasonal and longer-term cycles of freezing and thawing of the ice-rich ground cause these features to form over time. Whether the same is true for Mars is unknown. The polygons are located near 54.6°N, 326.6°W. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04905: Polygons near Lyot Crater sur le site de la NASA.PIA04902: Layer Outcrops and Dunes
MGS MOC Release No. MOC2-561, 1 December 2003
This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows dark, windblown sand dunes amid outcrops of light-toned, sedimentary rock in a crater in western Arabia Terra. The darkest material in the scene is windblown sand; the steep slopes--the slip faces--of the dunes face toward the southwest (lower left), indicating that wind transport of sand has been from the northeast (upper right). The layered mounds are the remains of sedimentary rock that were once more extensive across this crater floor. The image is located near 8.9°N, 1.2°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04902: Layer Outcrops and Dunes sur le site de la NASA.PIA04792: Albedo Boundary
MGS MOC Release No. MOC2-510, 11 October 2003
The sharp, nearly straight line that runs diagonally across the center of this April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an albedo boundary. Albedois a term that refers to reflectance of sunlight. A surface with a low albedo is one that appears dark because it reflects less light than a high albedo (bright) surface. On Mars, albedo boundaries occur between two materials of differing texture, particle size, or composition, or some combination of these three factors. The boundary shown here is remarkable because it is so sharp and straight. This is caused by wind. Most likely, the entire surface was once covered with the lower-albedo (darker) material that is now seen in the upper half of the image. At some later time, wind stripped away this darker material from the surfaces in the lower half of the image. The difference in albedo here might be related to composition, and possibly particle size. This picture is located near the southwest rim of Schiaparelli Basin at 5.5°S, 345.9°W. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.
Voir l'image PIA04792: Albedo Boundary sur le site de la NASA.PIA04743: Ascraeus Mons Pits
MGS MOC Release No. MOC2-482, 13 September 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of collapse pits on the northeast flank of the volcano, Ascraeus Mons. These pits are aligned along the trend of faults that are not well exposed at the surface; the faults are concentric to the volcano summit. The image is located near 13.0°N, 103.2°W. This picture covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA04743: Ascraeus Mons Pits sur le site de la NASA.PIA05740: South Polar Wind Drifts
11 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows evidence of wind deposition of fine sediment in the form of drifts in the lee of obstacles in the martian south polar region. The picture is located near 83.4°S, 8.1°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05740: South Polar Wind Drifts sur le site de la NASA.PIA05791: Fretted Terrain Valley
17 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical fretted terrain valley floor, located southwest of Moreux Crater near 40.3°N, 317.7°W. Prior to the MGS mission, images from the Viking and Mariner 9 orbiters led to speculation that the lineated floors of fretted terrain valleys indicated the results of flowing ice. MGS MOC images have shown that these lineations occur in closed, as well as open, fretted terrain valleys. The lineations might, therefore, have nothing to do with flowing ice. They might instead be an expression of eroded layered material. Studies of fretted terrain landforms are on-going within the Mars science community. This January 2004 image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05791: Fretted Terrain Valley sur le site de la NASA.PIA04676: Marte Vallis Platy Flows
MGS MOC Release No. MOC2-442, 4 August 2003
The Marte Vallis system, located east of Cerberus and west of Amazonis Planitia, is known for its array of broken, platy flow features. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a close-up view of some of these plates; they appear to be like puzzle pieces that have been broken apart and moved away from each other. The Mars science community has been discussing these features for the past several years--either the flows in Marte Vallis are lava flows, or mud flows. In either case, the material was very fluid and had a thin crust on its surface. As the material continued to flow through the valley system, the crust broke up into smaller plates that were then rafted some distance down the valley. This picture is located near 6.9°N, 182.8°W. It is illuminated by sunlight from the left.
Voir l'image PIA04676: Marte Vallis Platy Flows sur le site de la NASA.PIA05279: South Polar Scene
5 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the south polar residual cap. Sunlight illuminates this scene from the upper left, thus the somewhat kidney bean-shaped features are pits, not mounds. These pits and their neighboring polygonal cracks are formed in a material composed mostly of carbon dioxide ice. The image is located near 87.0°S, 5.7°W, and covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05279: South Polar Scene sur le site de la NASA.PIA04783: Hellas Planitia
MGS MOC Release No. MOC2-505, 6 October 2003
Northwest Hellas Planitia presents an array of strange-looking surfaces. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example near 39.3°S, 306.7°W. The scene is illuminated by sunlight from the upper left. Some of the banding apparent in this image may be related to layering, but the overall cause for the patterns remains elusive. Hellas Basin is a difficult place to obtain MOC high resolution images, because for most of the year it is cloudy. The clouds clear up and imaging opportunities are spectacular in southern autumn, the time of year that this image was obtained. This picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04783: Hellas Planitia sur le site de la NASA.PIA04837: Valley Floor
MGS MOC Release No. MOC2-529, 30 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the floor of an ancient valley located near the Pyrrhae Chaos region of Mars. This valley might have been carved by liquid water, but today no evidence remains that a fluid ever flowed through it. Long after the valley formed, its floor was covered by large, windblown, ripple-like dunes. This picture is located near 13.0°S, 31.2°W. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04837: Valley Floor sur le site de la NASA.PIA04755: Ceraunius Caldera Floor
MGS MOC Release No. MOC2-489, 20 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the pitted floor of the caldera of the martian volcano, Ceraunius Tholus. A caldera is a large collapse pit at the summit of a volcano. For reference, a wide angle MOC view of Ceraunius Tholus was presented on 18 April 2002,
"Volcanoes Ceraunius Tholus and Uranius Tholus." Today's picture shows a close-up view of the volcano's caldera floor. The floor exhibits many pits and holes, but it is uncertain whether these were formed by meteor impact, volcanic eruptions, or collapse. Most of them do not have raised rims and ejecta-two features characteristic of meteor impact craters (although a few shown here have raised rims); and none have lava flows or volcanic cones associated with them-characteristics of volcanic eruption. Thus, these pits might have formed by collapse, although it is more likely that they were formed by meteor impact, but the ejecta and rims have been buried by dust or eroded away. This picture is located near 24.3°N, 97.4°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04755: Ceraunius Caldera Floor sur le site de la NASA.PIA04784: Flows of Olympus
MGS MOC Release No. MOC2-506, 7 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a series of dust-covered, overlapping lava flows on the lower southeast flank of the giant martian volcano, Olympus Mons. Leveed channels are abundant; they were the conduits through which molten lava was transported down the length of each flow. This picture is located near 14.3°N, 132.3°W, and covers an area 3 km (1.9 mi) wide. The image is illuminated by sunlight from the lower left.
Voir l'image PIA04784: Flows of Olympus sur le site de la NASA.PIA04914: Small Dust Storm in Syria/Claritas
MGS MOC Release No. MOC2-567, 7 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle image shows a small dust storm, and several other smaller dust plumes, billowing up from the light-toned plains near the boundary between Syria Planum and the Claritas Fossae. This (text missing) is monitored by MOC several times a week because it is frequently the site of small dust storms and extremely large dust devils. The image covers an area approximately 125 km (78 mi) wide and is illuminated from the left/lower left.
Voir l'image PIA04914: Small Dust Storm in Syria/Claritas sur le site de la NASA.PIA05796: Hill in Propontis
22 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a rounded knob in the Propontis region of Mars near 43.1°N, 182.3°W. Dark dots on the hilltop and slopes are house-sized (and larger) boulders. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05796: Hill in Propontis sur le site de la NASA.PIA04727: Dune and Dust Devil Streaks
MGS MOC Release No. MOC2-474, 5 September 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a dark sand dune on the floor of a crater at 54.9°S, 342.5°W. Recent dust devils have disrupted a thin coating of dust on the otherwise dark dune; these wind phenomena created the plethora of markings and streaks on the dune. The image covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04727: Dune and Dust Devil Streaks sur le site de la NASA.PIA04842: Frosty Wind Streaks
MGS MOC Release No. MOC2-532, 2 November 2003
As seasonal polar frosts sublime away each spring, winds may re-distribute some of the frost or move sediment exposed from beneath the frost. This action creates ephemeral wind streaks that can be used by scientists seeking to study the local circulation of the martian [missing text] surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of wind streaks created in subliming carbon dioxide frost. These dark streaks appear to conform to the shape of the slopes on which they occur, suggesting that slope winds play a dominant role in creating and orienting these streaks. This picture is located near 73.8°S, 305.7°W. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide. Winds responsible for the streaks generally blew from the bottom/right (south/southeast) toward the top/upper left (north/northwest).
Voir l'image PIA04842: Frosty Wind Streaks sur le site de la NASA.PIA04678: Pedestal Crater and Yardangs
MGS MOC Release No. MOC2-444, 6 August 2003
This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact crater that has been modified by wind erosion. Two things happened after the crater formed. First, the upper few meters of surface material into which the meteor impacted was later eroded away by wind. The crater ejecta formed a protective armor that kept the material under the ejecta from been blown away. This caused the crater and ejecta to appear as if standing upon a raised platform--a feature that Mars geologists call a pedestal crater. Next, the pedestal crater was buried beneath several meters of new sediment, and then this material was eroded away by wind to form the array of sharp ridges that run across the pedestal crater's surface. These small ridges are known as yardangs. This picture is illuminated by sunlight from the upper left; it is located in west Daedalia Planum near 14.6°S, 131.9°W.
Voir l'image PIA04678: Pedestal Crater and Yardangs sur le site de la NASA.PIA04720: Defrosting Sand
MGS MOC Release No. MOC2-468, 30 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle camera image, acquired in July 2003, shows a field of eroded dunes and patches of sand covered by carbon dioxide frost that accumulated during the previous winter. This springtime view shows that the frost has begun to sublime away, leaving dark patches and streaks on the dune surfaces. Wind has blown across the terrain, as well, causing some of the dark spots to elongate toward the left (west). The sand is located in a depression near 78.5°S, 254.3°W. Sunlight illuminates the scene from the upper left. The area shown is about 3 km (1.9 mi) wide.
Voir l'image PIA04720: Defrosting Sand sur le site de la NASA.PIA04845: Gullies in Nirgal
MGS MOC Release No. MOC2-535, 5 November 2003
This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle image of gullies carved into debris on the south-facing wall of Nirgal Vallis, an ancient martian valley. The gullies were conduits for sediment that has accumulated at a point where each channel met the valley floor. The aprons of debris are superposed upon the large ripple-like dunes, suggesting that the gullies are younger than these bedforms. Gullies such as these might have been formed by a liquid, such as water, seeping from the layered bedrock exposed in the valley wall, or perhaps by mass movement of the smooth-surfaced debris that covers much of the lower two-thirds of the valley wall. This picture is located near 28.6°S, 41.5°W. The image covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04845: Gullies in Nirgal sur le site de la NASA.PIA05857: Pollack Crater 'White Rock'
2 May 2004
The "White Rock" of Pollack Crater is a feature that has been known since it was first observed by Mariner 9 in 1972. It is not actually white, but is much brighter than the fields of large, dark, windblown ripples that surround it. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture provides the highest resolution view, ever, of a portion of the wind-eroded "White Rock" feature. The rock materials are believed to be the remains of sediment that once covered the floor of Pollack Crater. Wind has sculpted the light-toned material into ridges and troughs known as yardangs. This 1.5 meters per pixel (5 feet per pixel) image is located near 8.1°S, 335.2°W. It was acquired in late March 2004, is illuminated from the left/upper left, and covers an area about 3 km (1.9 mi) across.
An earlier MOC view of "White Rock" can be seen in: "White Rock" of Pollack Crater, 4 December 2000. See PIA02848 and PIA02849.
Voir l'image PIA05857: Pollack Crater 'White Rock' sur le site de la NASA.PIA04870: Circles and Streaks
MGS MOC Release No. MOC2-544, 14 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired less than a week ago on 8 November 2003, shows a typical southern middle-to-high latitude scene at this time of year. It is summer in the southern hemisphere, and regions such as Promethei Terra, where this image was acquired, are being streaked by dust devils that remove or disrupt the coating of dust that was deposited over the region in the previous autumn or winter. While no active dust devils were captured in this scene, their tell-tale tracks are scratched all across the image. The circular features are the sites of buried meteor impact craters; their rims form dark rings; the material that fills the craters has become cracked. This picture is located near 68.1°S, 247.9°W. The area shown is approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04870: Circles and Streaks sur le site de la NASA.PIA05242: Dunes in Twilight
17 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows frost-covered north polar dunes in early January 2004. When this picture was taken, the dunes were in twilight, just before the late winter dawn that would come a few days later. These dunes spent many of the last several months in complete darkness. In this image, they are illuminated only by sunlight that has been scattered over the horizon by the martian atmosphere. These dunes are located near 77.0°N, 246.2°W. The image covers an area 3 km (1.9 mi) wide and has been expanded by 200% from its original 12 meters (39 ft.) per pixel scale. While the sun had not yet risen when the image was obtained, illumination is mostly from the lower left.
Voir l'image PIA05242: Dunes in Twilight sur le site de la NASA.PIA05534: Large Boulders in a Trough
8 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the walls and floor of a wide trough in the Sirenum Fossae region near 26.4°S, 140.7°W. Boulders rolled down the trough walls as they eroded out of the rock outcrops exposed on the upper slopes. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05534: Large Boulders in a Trough sur le site de la NASA.PIA05293: Sand Dunes in Noachis Terra
11 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-toned sand dunes in a crater in eastern Noachis Terra. Most big martian dunes tend to be dark, as opposed to the more familiar light-toned dunes of Earth. This difference is a product of the composition of the dunes; on Earth, most dunes contain abundant quartz. Quartz is usually clear (transparent), though quartz sand grains that have been kicked around by wind usually develop a white, frosty surface. On Mars, the sand is mostly made up of the darker minerals that comprise iron- and magnesium-rich volcanic rocks--i.e., like the black sand beaches found on volcanic islands like Hawaii. Examples of dark sand dunes on Earth are found in central Washington state and Iceland, among other places. This picture is located near 49.0°S, 326.3°W. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05293: Sand Dunes in Noachis Terra sur le site de la NASA.PIA05707: Gullies in Crater
2 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies in the wall of a large southern mid-latitude impact crater located near 39.8°S, 202.0°W. The gullies might have formed by transport of water and sediment down these crater slopes. Alternatively, a fluid other than water may have been involved (e.g., carbon dioxide), but most investigators agree that water is most likely. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05707: Gullies in Crater sur le site de la NASA.PIA05865: Clouds over Opportunity Site
4 May 2004
In recent weeks, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) blue wide angle images have been showing clouds high in the atmosphere over the Mars Exploration Rover (MER-B), Opportunity, landing site in Meridiani Planum. This view of the sunward limb of Mars shows an example. It was acquired by the MOC blue camera late last week on 29 April 2004. The "x" shows the location of the rover site. The bright features in this image are water ice clouds. The dark portion of the image on the left is outer space. Clouds can also be seen in a zone approximately 20 to 40 kilometers (12-25 miles) above the martian limb. North is approximately up, east is toward the right, and sunlight illuminates the scene from the left (west). The image runs along the limb from about latitudes 4°S to about 2°N.
Voir l'image PIA05865: Clouds over Opportunity Site sur le site de la NASA.PIA05700: Russell Dunes
26 March 2004
Dark streaks made by dozens of spring and summer dust devils created a form of martian graffiti on the sand dunes of Russell Crater near 54.5°S, 347.4°W. Gullies have developed on some of the dune slopes, as well. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05700: Russell Dunes sur le site de la NASA.PIA05245: Layers Near South Crater
20 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layer outcrops near the rim of South Crater, in the south polar region of Mars. These ancient layered materials surround an even older knob--the rounded feature at right/center. This picture is located near 78.0°S, 336.0°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05245: Layers Near South Crater sur le site de la NASA.PIA04877: South Polar Layers
MGS MOC Release No. MOC2-548, 18 November 2003
The south polar region of Mars exhibits thick exposures of layered sediment. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example of layers exposed on a slope. The image was obtained during southern summer in early November 2003. Sunlight illuminates the layers from the upper left; the lowest layers are at the top of the image; the slope goes up-hill toward the bottom. This area is located near 86.0°S, 182.4°W, and covers an area approximately 3 km (1.9 mi) wide.
Voir l'image PIA04877: South Polar Layers sur le site de la NASA.PIA05294: Crater Floor Bands
12 February 2004
The somewhat concentric bands in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image may be an expression of eroded layered material. The crater in which these occur is found at middle southern latitude near the west rim of the giant Hellas impact basin. The picture is located near 36.6°S, 321.2°W. Sunlight illuminates the scene from the upper left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05294: Crater Floor Bands sur le site de la NASA.PIA05533: West Candor Layers
7 March 2004
West Candor Chasma, one of the wide troughs of the great Valles Marineris canyon system, exhibits some of the most spectacular, varied, and extensive layered rock outcrops on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the layers of sedimentary rock exposed in west Candor Chasma near 5.9°S, 75.6°W. The picture covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the left/lower left.
Voir l'image PIA05533: West Candor Layers sur le site de la NASA.PIA04638: Southern Auqakuh Vallis
MGS MOC Release No. MOC2-421, 14 July 2003
Auqakuh Vallis located in northeastern Arabia Terra, an eroded, cratered highland terrain. Because erosion has removed hundreds of meters (or more) of material from the terrain surrounding Auqakuh Vallis, the valley today appears to be much shallower and wider than it was when it formed. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a shallow reach of the valley at its southernmost extent. The valley floor runs east-west (left-right) across the center of this picture. The floor of the valley has several dozen large, windblown ripples on it. The surrounding terrain has been eroded to form mesas and a few nearly-straight ridges known as dikes. This picture, acquired in July 2003, is located near 27.7°N, 298.0°W. The image covers an area 3 km (1.9 mi) across and is illuminated from the lower left.
Voir l'image PIA04638: Southern Auqakuh Vallis sur le site de la NASA.
PIA04805: North Nilosyrtis Mesas
MGS MOC Release No. MOC2-518, 19 October 2003
This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows mesas and troughs in the northern Nilosyrtis Mensae region of Mars. The larger mesas are capped by boulders or small knobs which are probably the eroded remnants of a layer of rock. The picture is located near 37.8°N, 282.5°W and covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the lower left.
Voir l'image PIA04805: North Nilosyrtis Mesas sur le site de la NASA.PIA04760: Melas Dust Storm
MGS MOC Release No. MOC2-493, 24 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows a dust storm raging in the Valles Marineris troughs, Melas Chasma and Ius Chasma. Skies are clear over western Candor Chasma (upper right). MOC images have shown that Mars has many weather phenomena that repeat, like clockwork, from year to year. This picture was taken during southern winter at a time of year that commonly has dust storms that come up from the plains south of the Valles Marineris, then enter the southern chasms of Ius and Melas. The picture is located at 8°S, 77°W, and covers an area 246 km (153 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04760: Melas Dust Storm sur le site de la NASA.PIA05120: Mars Exploration Rover (MER-A) Spirit Landing Site
3 January 2004
Excitement builds as the first Mars Exploration Rover (MER-A), Spirit, prepares to land on Mars just after 8:35 p.m. Pacific Standard Time today, 3 January 2004 (04:35, 4 January 2004 UTC). Today's Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture is a mosaic of MOC images of the Spirit landing site. The rover is expected to land somewhere within the approximately 83 km (~52 mi) long by ~10 km (~6 mi) wide ellipse on the floor of Gusev Crater. Clicking on the image above will show a map of the landing site at 25 meters (82 feet) per pixel. MOC has acquired 71 pictures of the landing site over a period spanning 3 Mars years (from July 1999 through December 2003), and more than 85 pictures were acquired within Gusev Crater specifically to support the Mars Exploration Rover landing site selection process. These pictures were acquired not only in different years, but in different seasons, so the illumination angle, overall brightness, and patterns of ephemeral, dark dust devil streaks and wind streaks are different from image to image within the mosaic. In areas where no MOC coverage exists, gaps were filled using images from the Mars Odyssey Thermal Emission Imaging System (THEMIS) visible imager, a lower-resolution camera built by Malin Space Science Systems and operated by Arizona State University. The Gusev Crater landing ellipse is centered near 14.8°S, 184.8°W. Sunlight illuminates each image in the mosaic from the left (in some cases, upper left, in others, lower left).
Spirit will land at about 2 p.m. local time on Mars. At the same time, Mars Global Surveyor will pass over the site and listen for a transmission of Spirit's entry, descent, and landing data. These data will be relayed back to Earth by the MOC. For more information about the Mars Exploration Rovers, visit
NASA/JPL's Mars Exploration Program Web site. For more information about the work that Malin Space Science Systems and MGS MOC are doing in support of the rover missions, see:
http://www.msss.com/mer_mission/. For information about how MSSS will use this mosaic of the landing site to help find Spirit after it touches down, see
Finding MERs.
Voir l'image PIA05120: Mars Exploration Rover (MER-A) Spirit Landing Site sur le site de la NASA.PIA04695: Crater and Wind Streak
MGS MOC Release No. MOC2-461, 23 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater with a bright wind streak in southern Acidalia Planitia. The streak is mostly likely a very thin coating of dust. The orientation of the streak indicates that the winds responsible for its formation and maintenance came from the northeast (upper right) and blew toward the lower left (southwest). The crater is located near 24.8°N, 39.1°W. The image covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04695: Crater and Wind Streak sur le site de la NASA.PIA04692: Intracrater Dune Field
MGS MOC Release No. MOC2-458, 20 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of dark sand dunes trapped on the floor of a crater near Cerberus at 8.6°N, 190.9°W. The local winds within the crater have shaped these dunes such that they all reflect a general trend of sand transport toward the west and southwest (left/lower left). This image covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left/lower left.
Voir l'image PIA04692: Intracrater Dune Field sur le site de la NASA.PIA05709: South Polar Mesas and Hills
4 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a mesa and two hills-each of them a remnant of formerly more extensive layered material--in the south polar region of Mars. The dark streaks were formed by passing dust devils. This picture is located near 64.6°S, 340.5°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05709: South Polar Mesas and Hills sur le site de la NASA.PIA05127: Frosty North Polar Dunes
10 January 2004
While it is summer in Gusev Crater, where the Mars Exploration Rover, Spirit, is operating, it is winter in the martian northern hemisphere. Just this week, the north polar dune fields began to emerge into sunlight after months of frigid darkness. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) view of frost-covered north polar dunes was acquired on 8 January 2004. The steepest slopes on the dunes--their slipfaces--point toward the upper right (northeast), indicating that the dominant winds responsible for their formation came from the opposite direction (lower left, southwest). Sunlight illuminates these dunes from the lower left, which may seem surprising because the brightest slopes on the dunes face the lower right. The brighter slopes are a frost phenomenon; most likely, these are areas with thicker frost deposits. In summer, the dunes would not have frost and would appear much darker than their surroundings. This early view of north polar dunes in winter is located near 75.8°N, 266.3°W. This view covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05127: Frosty North Polar Dunes sur le site de la NASA.PIA04767: Pits and Layers
MGS MOC Release No. MOC2-497, 28 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the scarps, mesas, and circular depressions of the south polar residual cap. These landforms are created in material consisting largely of frozen carbon dioxide. Each layer is a record of a past, colder martian climate. This August 2003 picture is located near 86.9°S, 342.8°W, and covers an area 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
Voir l'image PIA04767: Pits and Layers sur le site de la NASA.PIA05738: Olympian Flows
9 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lava flows and leveed lava channels on the lower northeast flank of the giant volcano, Olympus Mons. The image is located near 20.9°N, 130.5°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05738: Olympian Flows sur le site de la NASA.PIA04756: Exhumed Ridge Pattern
MGS MOC Release No. MOC2-490, 21 September 2003
The lower half of this June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an array of ridges arranged in a somewhat polygonal pattern. These ridges are being exhumed from within a blanket of material that covers the region south (toward the bottom) of this image. The origin of the ridges is not known; they might, for example, have started out as cracks and joints in the overlying material that became filled with coarser or cemented material that was left standing as solid ridges when the overlying sediment was eroded away. This picture is located near 11.0°N, 147.8°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04756: Exhumed Ridge Pattern sur le site de la NASA.PIA05201: Clouds near Phlegra Montes
14 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image shows mid-winter, afternoon cloud patterns over the northern end of the Phlegra Montes near 46°N, 192°W. The image, acquired in December 2003, covers an area approximately 579 km (354 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05201: Clouds near Phlegra Montes sur le site de la NASA.PIA05795: Pit Chain on Olympus
21 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a chain of collapse pits on the lower northeast flank of the large martian volcano, Olympus Mons. For these to have formed, something in the subsurface must have been removed or changed volume, such as cooling lava within a subsurface lava tube or extension of the crust by faulting. These pits are located near 20.6°N, 129.4°W. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05795: Pit Chain on Olympus sur le site de la NASA.PIA04672: Gale Sedimentary Rocks
MGS MOC Release No. MOC2-439, 1 August 2003
Gale Crater, located in the Aeolis region near 5.5°S, 222°W, contains a mound of layered sedimentary rock that stands higher than the rim of the crater. This giant mound suggests that the entire crater was not only once filled with sediment, it was also buried beneath sediment. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the eroded remains of the sedimentary rock that once filled Gale Crater. The layers form terraces; wind has eroded the material to form the tapered, pointed yardang ridges seen here. The small circular feature in the lower right quarter of the picture is a mesa that was once a small meteor impact crater that was filled, buried, then exhumed from within the sedimentary rock layers exposed here. This image is illuminated from the left.
Voir l'image PIA04672: Gale Sedimentary Rocks sur le site de la NASA.PIA05485: Meridiani Plains
This is a portion of a previously released image (PIA02397) taken by the Mars Orbiter Camera onboard NASA's Mars Global Surveyor, showing the dark, relatively smooth plains of Meridiani Planum, where the Mars Exploration Rover Opportunity landed. The larger circular features in the upper three-quarters of the image are thought to be the locations of buried craters formed by meteorite impacts. The cluster of smaller circular features in the bottom quarter of the scene represent a field of craters formed either by simultaneous impact of many meteorites, or impact of material thrown from a much, much larger nearby crater as it formed. The dark material covering these plains includes an abundance of the iron oxide mineral, hematite, that was detected by the Mars Global Surveyor thermal emission spectrometer. The scene is located near 2.2 degrees south, 3.7 degrees west and was acquired on August 19, 1999.
Voir l'image PIA05485: Meridiani Plains sur le site de la NASA.PIA04675: Labou Vallis
| | PIA04675: Labou Vallis
PIA05792.jpg = PIA05792: North Mid-latitude Crater
18 April 2004
Unlike southern mid-latitude craters, many northern mid-latitude craters do not have gullies but are instead partially filled with layered material. Often, the crater ejecta blankets are also partially covered. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical example located near 38.9°N, 185.3°W. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05792: North Mid-latitude Crater sur le site de la NASA.PIA04899: South Polar Sand Dunes
MGS MOC Release No. MOC2-560, 30 November 2003
This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes in the southern high latitudes of Mars. Unlike dunes at more northerly latitudes, south polar dunes tend to lack sharp, crisp features. Instead, they are often rounded, smoothed, and, in some cases (as toward the lower 1/3 of this image), flattened. These observations suggest that south polar dunes may be somewhat cemented and are presently (or fairly recently in the past) undergoing erosion. This dune field is located near 63.7°S, 201.2°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the upper left.
Voir l'image PIA04899: South Polar Sand Dunes sur le site de la NASA.PIA04723: Hellas Planitia
MGS MOC Release No. MOC2-471, 2 September 2003
Hellas Planitia is the floor of a giant basin that originally formed by the impact of a large comet or asteroid at a very early time in martian history. Throughout most of the martian year, Hellas is a difficult target for the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) because it is often dusty and cloudy. The best time of year to observe Hellas Planitia occurs during the southern autumn season. The most recent best-time-of-year for Hellas imaging occurred in September and October 2002. This is a wide angle red camera image obtained in October 2002 that shows a large portion of Hellas Planitia at a scale of about 245 meters (268 yards) per pixel. The image covers an area about 290 km (180 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04723: Hellas Planitia sur le site de la NASA.PIA04897: Work of Wind on Pavonis Mons
MGS MOC Release No. MOC2-558, 28 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture presents a high resolution view of the thick, dust-mantled surface of the upper west flank of the volcano, Pavonis Mons. Strong slope winds move and redistribute some of the fine sediment on the surface of this volcano, creating a pattern of light and dark wind streaks. The cluster of craters near the center of the image, for example, have bright tails that indicate winds blew from the lower left (southwest) toward upper right (northeast). This image is located near 0.7°N, 113.4°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the left/lower left.
Voir l'image PIA04897: Work of Wind on Pavonis Mons sur le site de la NASA.PIA05118: "White Rock" of Pollack Crater
1 January 2004
The famous "White Rock" of Pollack Crater has been known for three decades; it was originally found in images acquired by the Mariner 9 spacecraft in 1972. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) close-up view, obtained in October 2003, shows some of the light-toned, wind-eroded sedimentary rock that makes up "White Rock." It is not actually white, except when viewed in a processed, grayscale image (in color, it is more of a light butterscotch to pinkish material). The sediment that comprises "White Rock" was deposited in Pollack Crater a long time ago, perhaps billions of years ago; the material was later eroded by wind. Dark, windblown ripples are present throughout the scene. This picture is located near 8.2°S, 335.1°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05118: "White Rock" of Pollack Crater sur le site de la NASA.PIA04919: Wind-Eroded Terrain near Olympus Mons
MGS MOC Release No. MOC2-569, 9 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows wind-eroded material, possibly sedimentary rock, among the ridges of the Lycus Sulci region west of Olympus Mons. The darker surfaces and the dark-toned ripples on those surfaces indicate there may be windblown sand present in these areas. This October 2003 picture is located near 17.8°N, 143.7°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04919: Wind-Eroded Terrain near Olympus Mons sur le site de la NASA.PIA04890: Layers in Crater Wall
MGS MOC Release No. MOC2-555, 25 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows layers exposed in the upper wall of a meteor impact crater, and the dry talus that has been shed from this layered slope. This September 2003 image is located near 30.2°N, 272.8°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the lower left.
Voir l'image PIA04890: Layers in Crater Wall sur le site de la NASA.PIA04841: Defrosting Scene
MGS MOC Release No. MOC2-531, 1 November 2003
This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows patterns created by subliming carbon dioxide frost in the south polar region of Mars. The circular feature on the west (left) side of the image is a meteor impact crater; its center is just out of view. The dark, spotted features at the bottom and right are patches of windblown sand that have been covered with frost. In this springtime image, the frost has been subliming away for several months. As frost is removed from the patches of sand, it creates a pattern of dark spots. This picture is located near 66.1°S, 322.6°W. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04841: Defrosting Scene sur le site de la NASA.PIA05703: Gullies With Bright Material
29 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a set of south middle-latitude gullies in a crater wall. Some of the gullies and the erosional alcoves that formed above them have cut and exposed a light-toned material. In the larger gully, this material has been transported down the slope, through the channel, to give the debris apron a lighter tone, as well. The origin of middle-and polar-latitude gullies on Mars remains an area of active debate and discussion within the Mars science community. Mass movement of debris, everyone agrees, has occurred. Unclear are the relative roles of water, ice, and carbon dioxide, if any, in the processes that created the gullies. The light-toned material exposed by the gullies is bedrock, not ice. These features occur near 38.8°S, 40.3°W. This February 2004 image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05703: Gullies With Bright Material sur le site de la NASA.PIA04808: Crater Cluster
MGS MOC Release No. MOC2-521, 22 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cluster of impact craters in northwest Arabia Terra near 30.4°N, 13.7°W. This group of craters may have formed either by secondary impact of debris thrown out of a larger meteor crater, or by the break-up and impact of many fragments from a single incoming object. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA04808: Crater Cluster sur le site de la NASA.PIA04698: Summertime Dust Devil
MGS MOC Release No. MOC2-464, 26 August 2003
Dust devils are spinning, columnar vortices of air that move across a landscape, picking up dust as they go. They are common occurrences during summer on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer, shows a dust devil in the Phlegra region of Mars near 32.0°N, 182.1°W. Sunlight illuminates the scene from the lower left; the dust devil is casting a columnar shadow toward the upper right. Some dust devils on Mars make streaks as they disrupt the fine coating of dust on the surface--but others do not make streaks. This one did not make a streak. The view shown here is 3 km (1.9 mi) wide.
Voir l'image PIA04698: Summertime Dust Devil sur le site de la NASA.PIA04874: Meridiani Sedimentary Rocks
MGS MOC Release No. MOC2-545, 15 November 2003
Northern Sinus Meridiani is a region of vast exposures of layered, sedimentary rock. Buried within these layers are many filled impact craters. Erosion has re-exposed several formerly-buried craters in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Arrows 1 and 2 indicate craters that are still emerging from beneath layered material; arrow 3 indicates a crater that has been fully re-exposed. This image is located near 5.1°N, 2.7°W. The area shown is about 3 km (1.9 mi) wide and illuminated from the left/upper left.
Voir l'image PIA04874: Meridiani Sedimentary Rocks sur le site de la NASA.PIA05246: Daedalia Wind Streak
21 January 2004
This January 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark wind streak in the lee of a small meteor impact crater in Daedalia Planum. The dominant winds responsible for this streak blew from the east (right). This picture is located near 17.1°S, 138.8°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
Voir l'image PIA05246: Daedalia Wind Streak sur le site de la NASA.PIA05297: Becquerel Beckons
15 February 2004
Calling out across millions of miles of space, the compelling dark sand dunes and light-toned sedimentary rock outcrops of Becquerel Crater and dozens of other layered rock sites on Mars beg for further scientific investigation. Layered rocks record the history of a place; the younger layers are above the older ones. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the dunes and layered rocks in Becquerel, a ~170 km (~106 mi) wide crater in western Arabia Terra. Wind has blown the dunes toward the southwest (lower left). The image is located near 21.5°N, 8.6°W. Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05297: Becquerel Beckons sur le site de la NASA.PIA05530: North Polar Scarp
3 March 2004
The north polar cap of Mars overlies a series of layered materials. The upper-most layers are light-toned and may include ice and perhaps dust. The lower layers may be less icy and contain some amount of dark sand. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an exposure of north polar layers located near 83.9°N, 237.9°W. This view covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA05530: North Polar Scarp sur le site de la NASA.PIA05537: Layered Rock in West Candor
11 March 2004
West Candor Chasma, one of the troughs of the vast Valles Marineris system, presents some of the largest areas covered by outcrops of light-toned, layered rock on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located in west Candor near 6.1°S, 76.7°W. Hundreds of layers are exposed in this area. The dark ripples are believed to be just that--dark patches of windblown sediment shaped into rippled forms. Sunlight illuminates the scene from the lower left; the high resolution image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05537: Layered Rock in West Candor sur le site de la NASA.PIA05704: Crater in Cydonia
30 March 2004
Erosion has created a wide variety of landforms in the Cydonia region of Mars. Located in a zone of transition from cratered highlands to northern plains, Cydonia is a jumble of thousands of massifs, mesas, buttes, and hills---remnants of ancient cratered highlands in a state of advanced erosion. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater, slightly smaller than the famous 1 kilometer-diameter (0.62 miles) Meteor Crater in Arizona, U.S.A., that has been left standing high relative to the surrounding terrain because erosion removed most of the rock into which this crater originally formed. Later processes have mantled the crater and surroundings with debris that, at a finer scale, has also been eroded over time. This image occurs near 40.1°N, 13.6°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05704: Crater in Cydonia sur le site de la NASA.PIA04801: South Polar Layers
MGS MOC Release No. MOC2-516, 17 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded, stair-stepped layers in the south polar region of Mars. These layers have been considered, for the past three decades, to consist of a mixture of dust and ice. The Mars Polar Lander (MPL) mission was designed to test this hypothesis. However, sadly, MPL was lost during descent in December 1999. This exposure of south polar layered material is located near 86.3°S, 187.7°W. The image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
Voir l'image PIA04801: South Polar Layers sur le site de la NASA.PIA04806: Large Windblown Ripples
MGS MOC Release No. MOC2-519, 20 October 2003
This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image shows a depression in the martian southern cratered highlands near 1.3°S, 244.3°W. The floor of the depression and some nearby craters are covered by large windblown ripples or small sand dunes. This image of ancient martian terrain covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04806: Large Windblown Ripples sur le site de la NASA.PIA05123: Galle Crater Dunes
6 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes in southern Galle Crater, east of Argyre Planitia. The sand that comprises these dunes, like other dunes on Mars, is dark, but at the time this picture was acquired during early southern summer, the dunes were covered with a coating of bright dust. Occasional, passing dust devils or wind gusts created the dark streaks seen on a few of the dunes. The dunes are located near 51.9°S, 31.2°W. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05123: Galle Crater Dunes sur le site de la NASA.PIA04696: Hephaestus Fossae
MGS MOC Release No. MOC2-462, 24 August 2003
The Hephaestus Fossae are a series of collapsed pits and troughs in central Elysium Planitia. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) provides a high resolution view of the floors, walls, and terrain surrounding a few of the pits and troughs in this region. The image is located near 23.0°N, 239.4°W and is about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04696: Hephaestus Fossae sur le site de la NASA.PIA05248: MGS MOC Image of Mars Exploration Rover, Spirit, on Mars
Click on image for larger view 23 January 2004
The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), operating in martian orbit since September 1997, acquired an image of the Mars Exploration Rover (MER-A), Spirit, on 19 January 2004. The Spirit/Columbia Memorial Station is clearly seen as a bright feature in the image, as are the parachute and backshell from which Spirit was detached during the landing on 4 January 2004 (see inset for annotation). Also evident is a dark scar on the rim of a crater to the northeast of the lander; this dark marking was not present prior to landing, and is believed to have been caused by the impact of Spirit's heatshield. The lander is white because the data received from Mars were saturated at this location--that is, the lander was so much brighter than the surrounding terrain that the camera saw it as a white object.
The image shown here is located in Gusev Crater near 14.7°S, 184.6°W. North is up and sunlight illuminates each image from the left. The MOC image was acquired near 2 p.m. local time on Mars. The lander appears white because the DNs (data numbers) received from Mars for the lander were 255--the maximum possible (i.e., the lander was saturated). The values were saturated because of the high sun elevation angle and the fact that the lander and parachute are covered with highly reflective, light-toned materials (as seen in the
lander portrait released on 21 January 2004).
Voir l'image PIA05248: MGS MOC Image of Mars Exploration Rover, Spirit, on Mars sur le site de la NASA.PIA05299: Third MOC View of Opportunity Landing Site
17 February 2004
Around 19:03 UTC on 15 February 2004, the Mars Global Surveyor (MGS) spacecraft flew almost directly over the Mars Exploration Rover (MER-B), Opportunity, landing site. The MGS Mars Orbiter Camera (MOC) team decided, therefore, to take MOC's third picture of the lander. Unlike the previous two images, this attempt did not require rolling the spacecraft to hit the target. The image shows the location of the lander in its small impact crater; it also shows the locations of the parachute/backshell and the area disturbed by landing rockets and the first bounce. The heat shield impact site was too far east for the camera to view. The Opportunity landing site is near 2.0°S, 5.6°W in Meridiani Planum. Sunlight illuminates the scene from the left. The 150 meter scale bar is about 164 yards long. The image is not map-projected; north is toward the top/upper right.
Voir l'image PIA05299: Third MOC View of Opportunity Landing Site sur le site de la NASA.PIA05695: Gullied Slope
20 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies and debris aprons in a crater near 38.5°S, 174.5°W. Gullies such as these may have formed by running water, carbon dioxide, or dry mass movement processes. Most investigators of martian gullies consider that water, whether fresh or briney, may have been involved. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05695: Gullied Slope sur le site de la NASA.PIA04772: North Polar Dunes
MGS MOC Release No. MOC2-499b, 30 September 2003
The steepest slope on a sand dune, the slipface, indicates the general direction that wind has been transporting sediment. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several dark sand dunes in the north polar region. Sand transport in this case is from the lower left (southwest) toward the upper right (northeast). The picture is located near 76.5°N, 257.4°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04772: North Polar Dunes sur le site de la NASA.PIA05644: South Polar Pit Gullies
22 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies and slopes in the walls of a deep pit in the south polar region. The full-resolution (1.5 m/pixel; 5 ft./pixel) image is located near 71.1°S, 358.8°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05644: South Polar Pit Gullies sur le site de la NASA.PIA05259: Dune and Dust Devil Tracks
31 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark sand dune patch that occurs on the floor of a southern hemisphere crater near 64.1°S, 197.2°W. Passing dust devils have disrupted the fine, bright dust that coats the surrounding terrain, leaving wildly-varied streak patterns. Dark dots to the left (west) of the dune are boulders. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05259: Dune and Dust Devil Tracks sur le site de la NASA.PIA04687: Southeast Olympus Mons
MGS MOC Release No. MOC2-453, 15 August 2003
Olympus Mons is perhaps the largest volcano in the Solar System. It towers to more than 20 km above the martian datum--the elevation of 0 km--and it is wide enough to stretch east to west across the U.S. state of Arizona. This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the lava flows and leveed lava channels on the southeastern flank of Olympus Mons. These flows have been covered by a thick mantle of dust. The image is located near 14.4°N, 132.0°W and covers an area 3 km (1.9 mi) across at 1.5 m (5 ft.) per pixel. The scene is illuminated from the lower left.
Voir l'image PIA04687: Southeast Olympus Mons sur le site de la NASA.PIA05805: Lava Flows in Tharsis
24 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows details on large lava flows in the Tharsis volcanic region of Mars. The image is located near 25.4°N, 123.7°W. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05805: Lava Flows in Tharsis sur le site de la NASA.PIA04656: Stair-stepped Mound
MGS MOC Release No. MOC2-429, 22 July 2003
This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a stair-stepped mound of sedimentary rock (right of center) on the floor of a large impact crater in western Arabia Terra near 11.0°N, 4.4°W. Sedimentary rock outcrops are common in the craters of this region. The repeated thickness and uniformity of the layers that make up this mound suggest that their depositional environment was one in which cyclic or episodic events occurred over some period of time. The sediments might have been deposited in a lake, or they may have settled directly out of the atmosphere. Most of the layered material was later eroded away, leaving this circular mound and the other nearby mesas and knobs. The image is illuminated by sunlight from the lower left.
Voir l'image PIA04656: Stair-stepped Mound sur le site de la NASA.PIA05528: Knob in Propontis
1 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a rounded hill, or knob, in the Propontis region of Mars near 43.7°N, 189.1°W. This knob is a remnant of a former terrain, perhaps the remains of an old crater rim, or eroded upland. Dark specks on its surface may be large boulders. Old impact craters are seen in the lower third (southern third) of the image. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05528: Knob in Propontis sur le site de la NASA.PIA04680: Northeast Hellas Landscape
MGS MOC Release No. MOC2-446, 8 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of pitted terrain northeast of Hellas Basin shows light-toned outcrops of layered, sedimentary rock, and a valley floor covered by large, dark ripples or small dunes. Similar light-toned sedimentary materials are found throughout the region immediately northeast of Hellas, and in the crater, Terby. The area shown is 3 km (1.9 mi) wide and located near 27.5°S, 281.7°W. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04680: Northeast Hellas Landscape sur le site de la NASA.PIA05802: Wind Streak in Acidalia
23 April 2004
Thin deposits of bright dust often form tails in the lee of craters in Acidalia Planitia. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example from southern Acidalia near 23.0°N, 39.6°W. The dominant winds blow from the upper right (northeast) toward the lower left (southwest). The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05802: Wind Streak in Acidalia sur le site de la NASA.PIA05011: Syrtis Major Dune Field
20 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows barchan sand dunes west of the Meroe Patera volcanic caldera in central Syrtis Major. The winds that shape these dunes blow from the right/upper right (northeast). The surface across which the dunes have traveled is probably composed of volcanic rocks; the dunes, too, may have volcanic materials, such as sand-sized grains of tephra-volcanic ash-in them. This October 2003 view is located near 7.4°N, 292.3°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05011: Syrtis Major Dune Field sur le site de la NASA.PIA04775: Mesas and Troughs
MGS MOC Release No. MOC2-501, 2 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a grouping of mesas created by pitting and erosion of a layered material north of Apollinaris Patera near 1.7°S, 187.0°W. The terrain is mantled by dust and the troughs between the mesas exhibit large, ripple-like, windblown bedforms. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04775: Mesas and Troughs sur le site de la NASA.PIA05692: Kaiser Dunes
16 March 2004
Kaiser Crater, located in Noachis Terra near 46.5°S, 340.7°W, has some rather large, dark, sand dunes on its floor. Some of the dunes are seen in this February 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) view. Dark streaks on the dunes were formed by passing springtime and summer dust devils that disrupted a very thin, fine coating of dust on the dunes. The light-toned patch at the upper (north) end of this image is an exposure of the rock that underlies the dune field in Kaiser Crater. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05692: Kaiser Dunes sur le site de la NASA.PIA05643: Mid-Latitude Gullies
17 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies in the wall of a crater near 39.1°S, 200.7°W. Discussion among Mars scientists as to how martian middle-and polar-latitude gullies formed continues to this day. They were first observed in MGS MOC images and reported in June 2000. Most investigators agree that gullies, such as those shown here, were formed by running water, but disagree on whether the liquid came from snowmelt, groundwater, or melting ground ice. Still others argue that the fluid was carbon dioxide, and a few suggest that the gullies formed "dry"--that is, by landsliding processes involving no liquid or gas. This January 2004 MOC full-resolution (1.5 m/pixel; 5 ft./pixel) image is illuminated by sunlight from the upper left. The 300 m scale bar is approximately 984 ft. long.
Voir l'image PIA05643: Mid-Latitude Gullies sur le site de la NASA.PIA04810: Noachis Dust Storm
MGS MOC Release No. MOC2-523, 24 October 2003
The edges of the retreating seasonal polar caps of Mars are sites of frequent dust storms. The temperature contrast between the cold polar cap surfaces and the adjacent, warmer, frost-free surfaces set up the conditions for cold air to come streaming off the polar cap, picking up dust as soon as it hits the frost-free terrain. Dust storms are the result. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust storm in southeast Noachis Terra near 55°S, 316°W, on 21 June 2001. This was one of several precursor storms that led up to the global dust events of 2001. The frosted surface of the seasonal south polar cap is the lighter-toned terrain in the lower half of the image; the darker upper half is frost-free. Winds are blowing the dust storm (located at left-center) toward the north (top/upper right). The large crater just below the center of the picture is Peneus Patera. It is approximately 120 km (~75 mi) across. This MOC red wide angle picture is illuminated by sunlight from the upper left.
Voir l'image PIA04810: Noachis Dust Storm sur le site de la NASA.PIA05222: Frosty Polygons
16 January 2004
Looking somewhat like a roadmap, this 3 km (1.9 mi) wide view of a cratered plain in the martian south polar region shows a plethora of cracks that form polygonal patterns. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is located near 78.9°S, 357.3°W. Polygons such as these, where they are found on Earth, would be indicators of the presence of subsurface ice. Whether the same is true for Mars is uncertain. What is certain is that modern, seasonal frost on the surface enhances the appearance of the polygons as the frost persists longer in the cracks than on adjacent plains. This southern springtime image is illuminated by sunlight from the upper left.
Voir l'image PIA05222: Frosty Polygons sur le site de la NASA.PIA05281: Exhuming South Polar Crater
7 February 2004
The large, circular feature in this image is an old meteor impact crater. The crater is larger than the 3 kilometers-wide (1.9 miles-wide) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, thus only part of the crater is seen. The bright mesas full of pits and holes--in some areas resembling swiss cheese--are composed of frozen carbon dioxide. In this summertime view, the mesa slopes and pit walls are darkened as sunlight causes some of the ice to sublime away. At one time in the past, the crater shown here may have been completely covered with carbon dioxide ice, but, over time, it has been exhumed as the ice sublimes a little bit more each summer. The crater is located near 86.8°S, 111.6°W. Sunlight illuminates this scene from the upper left.
Voir l'image PIA05281: Exhuming South Polar Crater sur le site de la NASA.PIA05526: West Elysium Planitia Crater
28 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a middle northern latitude crater in western Elysium Planitia near 33.7°N, 257.8°W. The textured floor is a common feature at north and south middle latitudes, but its origin is not well understood. It is possible that sublimation of ice is a contributor to forming this texture, but it is just as possible that the processes do not involve ice or water in any form. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05526: West Elysium Planitia Crater sur le site de la NASA.PIA04862: South Polar Patterns
MGS MOC Release No. MOC2-540, 10 November 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the defrosting floor of a pit in the south polar region near 71.7°S, 1.6°W. The surface exhibits an array of cracks and bands that are emphasized by frost. Some of these are polygons similar to those that form in Earth's arctic and antarctic regions by processes of freezing and thawing of ground ice. Other bands might represent exposures of layered bedrock. Whether there is ice beneath the ground that has influenced the pattern of cracks and bands is unknown. This picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
Voir l'image PIA04862: South Polar Patterns sur le site de la NASA.PIA05715: Oblique Impact
| | PIA05715: Oblique Impact
PIA04700.jpg = PIA04700: Northeast Arabia Terra
MGS MOC Release No. MOC2-466, 28 August 2003
Northeast Arabia Terra is a heavily cratered region that has undergone considerable erosion. The erosion has exposed filled, buried meteor impact craters; it has also eroded craters down so that all that remains is the former floor of a crater. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the eroded terrain in northeast Arabia Terra near Huo Hsing Vallis. The terrain is layered, and these layers have been eroded. The dark feature toward the lower left may be the remains of a crater floor--the entire crater and the rock into which it formed have all been stripped away. This image is located near 29.6°N, 292.8°W. The picture covers an area 3 km (1.9 mi) across and is illuminated from the lower left.
Voir l'image PIA04700: Northeast Arabia Terra sur le site de la NASA.PIA05257: Tractus Fossae Pit Chain
29 January 2004
This January 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a chain of pits formed in a trough of the Tractus Fossae region near 24.1°N, 103.4°W. The troughs are graben, which are formed by faults cutting rock as the crust is stretched and extended, in this case toward the east and toward the west (right and left). As the rocks broke and moved along the fault lines that create the sharp cliffs on either side of the troughs, some materials between the trough walls collapsed along the fault trend to form the chain of pits. The picture covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05257: Tractus Fossae Pit Chain sur le site de la NASA.PIA04689: Top of Olympus Mons
MGS MOC Release No. MOC2-455, 17 August 2003
Olympus Mons is considered to be the largest and tallest volcano in the Solar System. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the western summit region of Olympus Mons. This area is at an elevation just over 20 km (12 mi) above the 0 km martian datum. The bright feature on the right (east) side of the image is the uppermost wall of the caldera (collapse pit) at the top of the volcano. This image shows a lava flow that was cut by the pit walls when the caldera collapse occurred. Below (south of) the lava flow is a narrow channel formed by lava at some time in the distant past. This view of the summit region of Olympus Mons is located near 10.6°N, 134.0°W. The area shown is about 7.9 km (4.9 mi) across. Sunlight illuminates the scene from the right.
Voir l'image PIA04689: Top of Olympus Mons sur le site de la NASA.PIA04658: Layers in Crater Cluster
MGS MOC Release No. MOC2-431, 24 July 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cluster of old, small impact craters near 36.3°N, 281.9°W. The group of craters was probably formed by secondary impacts following a much larger impact that occurred some distance away; the material that created these craters would have been the ejecta from the larger crater, rather than meteoroids from outer space. The craters cluster is considered to be relatively old because none of the craters have ejecta blankets any more, and each was filled, or partially filled, with layered material that was later eroded to form the terraced mounds found in their floors. This picture is illuminated from the lower left.
Voir l'image PIA04658: Layers in Crater Cluster sur le site de la NASA.PIA04798: Streamlined Island
MGS MOC Release No. MOC2-514, 15 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a streamlined island in Marte Vallis, a large outflow channel system that crosses the 180°W meridian between the Elysium and Amazonis regions of Mars. The flow patterns on the floor of Marte Vallis might be the remains of lava flows or mud flows. Marte is the Spanish word for Mars. Most of the largest valleys on the red planet are named for "Mars" in various languages. This island is located near 21.8°N, 175.3°W. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA04798: Streamlined Island sur le site de la NASA.PIA04974: Exhumed Crater with Slope
MGS MOC Release No. MOC2-575, 15 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater in Arabia Terra that has been exhumed. The picture was acquired less than 1 week ago, on 9 December 2003. The crater was buried beneath layered material, but erosion later brought it back to the surface. A thick blanket of dust mantles the scene; dark streaks have formed as some of this dust slid down the crater walls. Old, dust-covered ripples of windblown sediment occur on the floor of the exhumed crater. The image is located near 20.9°N, 320.7°W, and covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA04974: Exhumed Crater with Slope sur le site de la NASA.PIA05262: Defrosting South Polar Sand
2 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides a springtime view of defrosting processes on a surface that in summer would be a dark patch of sand. In winter, the sand is covered by frost (carbon dioxide and possibly water ice, as well). In spring, the sand develops a spotted pattern as the frosts sublime away. The sand patch is part of a dune field in Jeans Crater, located in the south polar region near 69.8°S, 206.6°W. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05262: Defrosting South Polar Sand sur le site de la NASA.PIA04735: Public-Requested Mars Image: Crater on Pavonis Mons
MGS MOC Release No. MOC2-481, 12 September 2003
This image is in the first pair obtained in the Public Target Request program, which accepts suggestions for sites to photograph with the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft.
It is a narrow-angle (high-resolution) view of a portion of the lower wall and floor of the caldera at the top of a martian volcano named Pavonis Mons. A companion picture is a wide-angle context image, taken at the same time as the high-resolution view. The white box in the context frame shows the location of the high-resolution picture.
Pavonis Mons is a broad shield volcano. Its summit region is about 14 kilometers (8.7 miles) above the martian datum (zero-elevation reference level). The caldera is about 4.6 kilometers (2.8 miles) deep. The caldera formed by collapse--long ago--as molten rock withdrew to greater depths within the volcano. The high-resolution picture shows that today the floor and walls of this caldera are covered by a thick, textured mantle of dust, perhaps more than 1 meter (1 yard) deep. Larger boulders and rock outcroppings poke out from within this dust mantle. They are seen as small, dark dots and mounds on the lower slopes of the wall in the high-resolution image.
The narrow-angle Mars Orbiter Camera image has a resolution of 1.5 meters (about 5 feet) per pixel and covers an area 1.5 kilometers (0.9 mile) wide by 9 kilometers (5.6 miles) long. The context image, covering much of the summit region of Pavonis Mons, is about 115 kilometers (72 miles) wide. Sunlight illuminates both images from the lower left; north is toward the upper right; east to the right. The high-resolution view is located near 0.4 degrees north latitude, 112.8 degrees west longitude.
Voir l'image PIA04735: Public-Requested Mars Image: Crater on Pavonis Mons sur le site de la NASA.PIA04881: Rocks Exposed on Slope in Aram Chaos
MGS MOC Release No. MOC2-550, 20 November 2003
This spectacular vista of sedimentary rocks outcropping on a slope in Aram Chaos was acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on 14 November 2003. Dark piles of coarse talus have come down the slopes as these materials continue to erode over time. Note that there are no small meteor impact craters in this image, indicating that erosion of these outcrops has been recent, if not on-going. This area is located near 2.8°S, 20.5°W. The 200 meter scale bar is about 656 feet across. Sunlight illuminates the scene from the lower right.
Voir l'image PIA04881: Rocks Exposed on Slope in Aram Chaos sur le site de la NASA.PIA04732: Layers in East Candor
MGS MOC Release No. MOC2-475, 6 September 2003
Eroded, layered sedimentary rock exposures are common in the chasms of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the layers in eastern Candor Chasma. Faulting has created the steep slope that runs left to right across the lower half of the image. About two-thirds of the way down this slope occurs a distinct change from a spur-and-gully slope morphology to a flatter topography overlain by piles of talus that have come down the slopes. This abrupt change might indicate the location of a fault. The picture is located near 7.2°S, 69.0°W and covers an area 3 km (1.9 mi) across. The scene is illuminated by sunlight from the left.
Voir l'image PIA04732: Layers in East Candor sur le site de la NASA.PIA04886: Crater Cluster Near Pathfinder
MGS MOC Release No. MOC2-552, 22 November 2003
This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a large cluster of small craters located northeast of the Mars Pathfinder landing site, on the plains scoured by the old Ares and Tiu Valles outflow channels. Clusters of craters, such as these, usually form as secondary impacts. Secondary impacts are the result of a larger, single meteor, asteroid, or cometary impact--the impact ejects debris that falls elsewhere and creates smaller, secondary craters. In other words, the material that hit the ground to form these craters did not come from space, it came from Mars. The craters are located near 19.9°N, 33.3°W. The image shows an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the lower left.
Voir l'image PIA04886: Crater Cluster Near Pathfinder sur le site de la NASA.PIA05845: Arkhangelsky Dunes
29 April 2004
These dark-toned barchan sand dunes in Arkhangelsky Crater were viewed by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in late southern summer on 17 February 2004. Hundreds of narrow, dark streaks crisscross the dunes and the interdune terrain; these were most likely formed by the disruption of fine sediment by passing dust devils. The dune field is located near 41.2°S, 25.0°W, and is illuminated by sunlight from the upper left. Dune horns and slip faces indicate that the dominant winds blow from the southwest (lower left). The picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05845: Arkhangelsky Dunes sur le site de la NASA.PIA05341: Wind vs. Dust Devil Streaks
22 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presents a fine illustration of the difference between streaks made by dust devils and streaks made by wind gusts. Dust devils are usually solitary, spinning vortices. They resemble a tornado, or the swirling motion of a familiar, Tasmanian cartoon character. Wind gusts, on the other hand, can cover a larger area and affect more terrain at the same time. The dark, straight, and parallel features resembling scrape marks near the right/center of this image are thought to have been formed by a singular gust of wind, whereas the more haphazard dark streaks that crisscross the scene were formed by dozens of individual dust devils, acting at different times. This southern summer image is located in Noachis Terra near 67.0°S, 316.2°W. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05341: Wind vs. Dust Devil Streaks sur le site de la NASA.PIA04973: Daedalia Dust Devil
MGS MOC Release No. MOC2-574, 14 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an active dust devil making its way across an intercrater surface in western Daedalia Planum. This picture, a MOC "classic," was obtained back in October 1999. Sunlight illuminates the scene [missing text] curved shadow cast by the spinning column of air can be seen to the right of the dust devil. This area is located near 10.0°S, 143.0°W. The image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04973: Daedalia Dust Devil sur le site de la NASA.PIA04888: Multiple-Event Gully
MGS MOC Release No. MOC2-554, 24 November 2003
Middle- and polar-latitude gullies are common on crater and trough walls in the martian southern hemisphere. Some also occur in the north. One of the controversies surrounding gullies is whether they involved fluid flow (such as liquid water) or were formed by dry landsliding processes. The occurrence of banked and leveed channels in many gullies argues that they formed by fluid flow. Another question centers on whether gullies are "one-shot deals" or involved more than one episode of fluid flow. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in November 2003, shows a gully with an apron, near the center of the frame, that formed by multiple fluid flows. The apron of debris at the base of the gully near the center of the picture is not just one apron, it is three. Three separate aprons formed at three different times. First, the larger, left-most apron formed. Later, another event caused fluid to cut through that apron and create a new one (the middle of the three). Later, a third event cut both aprons and formed a small, third one. This image shows the wall of an impact crater located near 51.3°S, 326.6°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the upper left.
Voir l'image PIA04888: Multiple-Event Gully sur le site de la NASA.PIA04664: Textured Memnonia Plain
MGS MOC Release No. MOC2-435, 28 July 2003
One of the goals of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Picture of the Day collection is to provide a sense of the great diversity of terrain, surfaces, patterns, and textures of the martian surface, as viewed by the MOC high resolution (narrow angle) camera. This image shows an intercrater plain in the Memnonia region that has been severely eroded by wind to form sharp ridges known as yardangs. This terrain would be very difficult to walk, or drive a rover, across. The picture is located near 11.8°S, 157.2°W. The scene is illuminated by sunlight from the left.
Voir l'image PIA04664: Textured Memnonia Plain sur le site de la NASA.PIA05024: Dust-Raising Event
29 December 2003
Small dust storms are common in the south polar region during summer. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of a south polar dust-raising event caught by the narrow angle camera. The small, somewhat circular features at the lower right of the frame are pits in the martian surface. Moving from the bottom to top of the image, first there is a view of the pitted surface, followed by a zone of long, thin streamers of dust being lifted from the surface, followed by -- at the top one third of the image -- the billowy clouds of the dust storm. This image is important because it shows long, thin streamers of dust actually being raised from the martian surface to feed the dust storm. The picture is located near 87.0°S, 170.6°W. The area shown is about 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
Voir l'image PIA05024: Dust-Raising Event sur le site de la NASA.PIA04791: Dark Sand Dunes
MGS MOC Release No. MOC2-509, 10 October 2003
This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in a crater north of Syrtis Major near 27.1°N, 297.2°W. The steepest slopes on each dune face toward the bottom/lower left of the image, indicating that the dominant winds that influenced their formation came from the north (the top of the image). Layers are exposed in a butte at the lower right corner of the picture; this butte is a remnant of layered rock that once covered the entire crater floor on which the dunes occur. This picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA04791: Dark Sand Dunes sur le site de la NASA.PIA05913: Channel on Ascraeus Mons
6 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a deep channel formed on the northern flank of the large volcano, Ascraeus Mons. Layers of volcanic rock are exposed in the channel walls, and the dark dots on the valley floor are boulders derived from erosion of these materials. The picture occurs near 14.5°N, 102.8°W, and is illuminated from the lower left. The picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05913: Channel on Ascraeus Mons sur le site de la NASA.PIA05210: Granicus Valles
15 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the troughs of the Granicus Valles system, located west of the Elysium volcanic rise near 27.1°N, 224.0°W. The floors exhibit abundant large ripple-like features deposited and shaped by wind. The dark dots on the valley floors are large boulders. The image covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the left.
Voir l'image PIA05210: Granicus Valles sur le site de la NASA.PIA04747: Landslide!
MGS MOC Release No. MOC2-486, 17 September 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part of a deposit created by a landslide off the wall of a crater near 12.3°N, 21.3°W. The crater wall is not shown; it is several kilometers to the left of this picture. The debris that slid from the crater wall came from the left/upper left (northwest) and moved toward the lower right (southeast). The crater floor onto which the debris was deposited has more small meteor craters on it than does the landslide material; this indicates that there was a considerable interval between the time when the crater floor formed, and when the landslide occurred. This picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04747: Landslide! sur le site de la NASA.PIA05914: Rock Slide in Ophir
7 May 2004
The dark streaks, just left of center, on the steep slope in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image were formed by a relatively recent rock slide. The streak closest to the center of the image resolves into a series of small depressions, indicating the path of a large, rolling boulder. The rock slide is inferred to have been recent (i.e., within the past several Mars years) because it is so much darker than its surroundings--there has not been sufficient time for the streak surfaces to become mantled by dust. The other talus accumulations on this slope are most likely lighter in tone because they are older and coated with dust. These features are located in Ophir Chasma, part of the Valles Marineris trough system, near 4.2°S, 74.0°W. The picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05914: Rock Slide in Ophir sur le site de la NASA.PIA05023: Alba Patera
28 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows much of Alba Patera, a low, broad shield volcano in northern Tharsis. The caldera complex--the pits formed by collapse at the volcano summit -- is located toward the bottom center of this image. Alba Patera is located at 41°N, 111°W. The area shown here is approximately 430 km (~270 mi) across and illuminated from the lower left.
Voir l'image PIA05023: Alba Patera sur le site de la NASA.PIA04663: Defrosting Sand Dunes
MGS MOC Release No. MOC2-434, 27 July 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows retreating patches of frost on a field of large, dark sand dunes in the Noachis region of Mars. Large, windblown ripples of coarse sediment are also seen on some of the dunes. This dune field is located in a crater at 47.5°S, 326.3°W. The scene is illuminated by sunlight from the upper left.
Voir l'image PIA04663: Defrosting Sand Dunes sur le site de la NASA.PIA05334: Martian Meteor Crater
20 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fairly young meteor impact crater on Mars that is about the same size (~ 1 kilometer; 0.62 miles) as the famous Meteor Crater in northern Arizona, U.S.A. Like the Arizona crater, boulders of ejected bedrock can be seen on the crater's ejecta blanket and in the crater itself. This crater is located in the Aethiopis region of Mars near 4.7°N, 224.1°W. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05334: Martian Meteor Crater sur le site de la NASA.PIA04807: Impact Crater
MGS MOC Release No. MOC2-520, 21 October 2003
Craters formed by meteor impact are the "tools of the trade" for planetary geologists. Craters have formed on every solid Solar System body, and thus they can be compared to each other and provide insights as to the nature of the object on which the crater occurs. Mars is pocked with craters of a wide range of diameters, from the giant Hellas Basin, which is several thousand kilometers across, to tiny craters of only a few tens of meters in diameter. The impact crater shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture is located in northern Elysium Planitia near 33.1°N, 230.2°W. It is about 3.6 km (2.2 mi) across, nearly four times the size of the famous Meteor Crater in northern Arizona on the North American continent. The impact that formed this crater exposed layered bedrock (visible in the upper walls of the crater). Erosion, mostly by dry mass movement, has created gullies and piles of talus on the crater walls. Dark dots at the base of the wall are large boulders that have come down these slopes. The picture covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left/lower left.
Voir l'image PIA04807: Impact Crater sur le site de la NASA.PIA05122: A Dynamic Spirit Site
5 January 2004
Two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images acquired before the spectacular January 2004 landing of the Mars Exploration Rover (MER-A), Spirit, show the area where the lander is currently believed to have touched down. The identification of the area shown in the two pictures above is based on the pictures acquired by Spirit's descent imaging system just before landing. The lower picture was obtained by MGS MOC on 22 July 2003, the upper picture was acquired less than a month ago on 10 December 2003. What is exciting about these two pictures is the differences in the patterns of dark, squiggly streaks. These streaks are believed to have been caused by the removal of bright dust by large, passing dust devils. Comparison of the picture from July 2003 with that of December 2003 show that a different dark streak pattern developed over a period of less than 5 months.
These two MOC images suggest that the landing site is a dynamic, changing place on the time scale of several months. MGS MOC has never seen a dust devil occur in
Gusev Crater, the location of the
Spirit landing site. MGS always flies over Gusev around 2 p.m. local time, so this means that dust devils are not believed to be common around 2 p.m. However, the changes in the dark streaks suggest that dust devils definitely have occurred in Gusev Crater over the past 5 to 6 months, and they most likely occur earlier than 2 p.m. (perhaps closer to local 1 p.m. or noon).
These two MOC images are simple cylindrical map projections (rotated somewhat; note the north arrow, N) at a scale of about 3 meters per pixel (~10 ft/pixel); the 300 meter scale bar is about two-tenths of a mile long. The images are located near 14.7°S, 184.6°W, and are illuminated from the left.
Voir l'image PIA05122: A Dynamic Spirit Site sur le site de la NASA.PIA04762: Polar Sand Dunes
MGS MOC Release No. MOC2-495, 26 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows windblown sand dunes in Chasma Boreale, a wide trough in the north polar region of Mars. The dunes are shown here in their summertime configuration; that is, they are not covered with seasonal frost. The dunes are dark because the grains that make up these sandy landforms consist of dark minerals and/or fragments of dark-toned rock. The steepest slopes on these dunes, their slipfaces, point toward the top/upper left (northwest), indicating that winds blow the sand from the lower right (southeast). This picture is located near 84.7°N, 359.3°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04762: Polar Sand Dunes sur le site de la NASA.PIA04697: Crumbled Mesa
MGS MOC Release No. MOC2-463, 25 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a mesa in the Avernus Colles region of Mars, near 3.9°S, 190.8°W. The mesa and the very large blocks that have been shed from its slopes are all that remain of a once much more extensive suite of layered rock that used to cover the entire area shown here. This full-resolution (1.5 meters--5 feet--per pixel) image covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.
Voir l'image PIA04697: Crumbled Mesa sur le site de la NASA.PIA05298: Complex Wind Streaks
16 February 2004
Northeastern Tharsis is known for its complicated patterns of wind streaks. Wind streaks are formed by sediment transport and deposition by wind. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a pattern of crisscrossing streaks indicating winds that generally blow from the southwest (lower left) toward northeast (upper right), but vary over time. The image is located near 27.6°N, 98.9°W. Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05298: Complex Wind Streaks sur le site de la NASA.PIA04641: Crater with Wavy Fog
MGS MOC Release No. MOC2-424, 17 July 2003
Craters near the edge of the retreating south polar seasonal frost cap often have fog in them, this time of year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image was acquired just a few days ago on July 13, 2003. It shows a crater, 36 km (22 mi) across, that is enveloped in fog. This picture was taken as a context frame for a high resolution view that was intended to show dunes on the floor of the crater. That high resolution view was frustrated by thick fog that hid the dunes from view. This wide angle context frame shows that winds from the lower right (southeast) were blowing over the crater, causing the fog to bunch up in a wavy, rippled pattern. Winds streaming off the polar cap toward the north create a variety of patterns in the fogs formed by water ice or vapor as the seasonal cap retreats during southern spring. This picture is located at 66.4°S, 208.6°W, sunlight illuminates the scene from the upper left (northwest).
Voir l'image PIA04641: Crater with Wavy Fog sur le site de la NASA.
PIA04690: South Polar Artwork
MGS MOC Release No. MOC2-456, 18 August 2003
Nature has created some interesting artwork on the south polar residual cap of Mars. This July 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The patterns in this picture are formed by erosion and sublimation of multiple layers of frozen carbon dioxide. The artwork is ephemeral and changing with each passing summer. By the end of the coming southern summer, the scarps in this area will have retreated an average of 3 meters (3.3 yards); some of the smaller buttes and ridges will have vanished. This picture covers an area 3 km (1.9 mi) wide and is located near 86.6°S, 358.2°W. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04690: South Polar Artwork sur le site de la NASA.PIA05316: Gullied Crater Wall
18 February 2004
Many craters and troughs at middle latitudes on Mars have gullies carved into their slopes. These gullies often have banked or even meandering channels that indicate a fluid with the properties of water may have been involved. Indeed, it is possible that such gullies indicate places where liquid water seeped out to the martian surface, or formed from melting ice, in the not-too-distant past. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located in a crater in Terra Cimmeria near 37.7°S, 191.6°W. The picture was acquired only a few months ago in November 2003. Sunlight illuminates the scene from the left/upper left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05316: Gullied Crater Wall sur le site de la NASA.PIA04719: Defrosting South Polar Slope
MGS MOC Release No. MOC2-467, 29 August 2003
Today, August 29, 2003, Mars Global Surveyor (MGS) completes its 20,000th orbit since the start of the mapping phase of the mission in March 1999. Each of the 20,000 nearly-polar, nearly-circular orbits around the planet takes about 2 hours. The spacecraft passes over each martian polar region twelve times a day. This July 2003 MGS Mars Orbiter Camera (MOC) image shows defrosting gullies and mass movement (landslide) features in the south polar region. This is a springtime view; all of the carbon dioxide and water ice that accumulated on the ground during the previous winter is subliming away. The different physical properties of the ground beneath the frost lead to differences in the length of time that a particular surface retains frost as spring progresses. Here, the areas that still have the most frost are the bright features associated with gullies and landslide deposits. These deposits may contain more sand than their surrounding terrain--we know from images of martian sand dunes that frost tends to linger a bit later in the spring on a sandy surface. This image is located near 70.7°S, 358.2°W. The slope bearing gullies and landslide materials is facing toward the bottom/lower right. Sunlight illuminates the scene from the lower right. This image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04719: Defrosting South Polar Slope sur le site de la NASA.PIA05186: South Polar Troughs
13 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows troughs eroded into the south polar residual cap. The residual cap is made largely of frozen carbon dioxide, which freezes on Mars at a temperature around 148 Kelvin (about -125°C, -193°F). When this picture was acquired in early summer during October 2003, the temperature at the surface probably was very close to 148 Kelvin (brrrr!). Sunlight illuminates this image from the upper left; it is located near 86.9°S, 15.7°W. The 200 meter scale bar is approximately 656 feet across.
Voir l'image PIA05186: South Polar Troughs sur le site de la NASA.PIA05536: Isidis Dust Devil
10 March 2004
This arrow in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image points to an active dust devil observed in Isidis Planitia near 18.3°N, 268.9°W. The columnar shadow of the dust devil is visible, as is a pencil-thin (at least, pencil-thin at the scale of the image) line created by the vortex as it disrupted the dust that coats the surface. The streak indicates that the dust devil had already traveled more than 3 kilometers (1.9 miles), over craters, large ripples, and ridges, before the MOC took this picture. The dust devil was moving from the northeast (upper right) toward the southwest (lower left). Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05536: Isidis Dust Devil sur le site de la NASA.PIA04987: Approximate Location of Spirit
| | PIA04987: Approximate Location of Spirit
PIA05705.jpg = PIA05705: West Candor Layers
31 March 2004
Western Candor Chasma, in the vast Valles Marineris trough system, has some of the most extensive and varied exposures of light- and dark-toned layered rock on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of layered rock exposed by erosion in west Candor. The materials are probably sedimentary rocks, although some investigators have argued for a volcanic origin. The image is located near 5.7°S, 75.8°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.
Voir l'image PIA05705: West Candor Layers sur le site de la NASA.PIA05702: Layered South Polar Slope
28 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed in the walls of a crater-like form (only partially seen here) in the south polar region. These layers record some of the history of the martian south pole, although deciphering this record will require human or robotic explorers to get a closer view. The layered outcrop is located near 84.6°S, 359.6°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05702: Layered South Polar Slope sur le site de la NASA.PIA04809: Fresh Impact Crater
MGS MOC Release No. MOC2-522, 23 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a young, fresh meteor impact crater in southeast Arabia Terra acquired in August 2003. The crater is inferred to be young because it still has a finely detailed pattern of rays associated with its ejecta. These rays formed in a dusty mantle that covers the other craters and rocky terrain at this locale. The crater is young enough that there has not been sufficient time for new dust to cover the rays, or for winds to erase them. The small dark dots associated with the crater are boulders. The boulders were ejected by the impact event. This crater is located near 6.9°S, 317.1°W. The picture covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA04809: Fresh Impact Crater sur le site de la NASA.PIA04699: Cerberus Fossae Trough
MGS MOC Release No. MOC2-465, 27 August 2003
The Cerberus Fossae are a series of semi-parallel troughs in the Cerberus region of Mars. They formed by extension (splitting) of the upper martian crust in the vicinity of the Elysium and Albor volcanoes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.5 meter (5 feet) per pixel view of one of the Cerberus Fossae troughs. Dark sediment and talus from the trough walls are visible, as are some of the layers in the subsurface exposed by the troughs. This feature is located near 15.7 °N, 197.5°W. The area shown is 3 km (1.9 mi) across. Sunlight illuminates the scene from the left/lower left.
Voir l'image PIA04699: Cerberus Fossae Trough sur le site de la NASA.PIA04875: Sabaeus Dust Devil
MGS MOC Release No. MOC2-546, 16 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an active dust devil in Sinus Sabaeus, southeast of Schiaparelli Basin. Sunlight illuminates the scene from the upper left (northwest). The dust devil is best recognized by the dark, columnar shadow it casts toward the lower right (southeast). This image is located near 5.4°S, 340.0°W. The area shown is about 3 km (1.9 mi) wide.
Voir l'image PIA04875: Sabaeus Dust Devil sur le site de la NASA.PIA05247: Layers in Crater Wall
22 January 2004
This January 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows three distinct bands of layered material exposed in the wall of a south, middle-latitude meteor impact crater wall. Talus--debris shed from erosion of the wall--has piled up on the slopes below the layered outcrop. This picture is located near 45.5°S, 85.9°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the right/lower right.
Voir l'image PIA05247: Layers in Crater Wall sur le site de la NASA.PIA05531: South Polar Polygons
4 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a spectacular suite of large and small polygons in the south polar region. On Earth, polygons such as these would be indicators of the presence of ground ice. Whether this is true for Mars remains to be determined, but it is interesting to note that these polygons do occur in a region identified by the Mars Odyssey Gamma Ray Spectrometer (GRS) team as a place with possible ground ice. The polygons are in an old impact crater located near 62.9°S, 281.4°W. This 1.5 meter (5 ft.) per pixel view covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left. To see the smaller set of polygons, the reader must view the full-resolution image (click on picture, above).
Voir l'image PIA05531: South Polar Polygons sur le site de la NASA.PIA05737: Ariadnes Colles
8 April 2004
The Ariadnes Colles is a cluster of light-toned knobs, mesas, and hills in Terra Cimmeria near 35°S, 188°W. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of these landforms. They might be the eroded remnants of material deposited in an extremely ancient impact basin. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05737: Ariadnes Colles sur le site de la NASA.PIA04759: Defrosting Richardson Dunes
MGS MOC Release No. MOC2-492, 23 September 2003
This is a mid-southern spring view, taken in August 2003, of defrosting patterns on sand dunes in Richardson Crater. The picture was acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). The frost on these dunes might be a combination of frozen carbon dioxide left over from the previous winter, and water ice. As the ices sublime away, they create dark spots. Winds create dark streaks, either by moving the dark sand that underlies the frost, or by removing frost to expose the sand. Alternatively, the frost itself is roughened by the wind or has been made coarse by wind and sublimation processes. The Richardson dune field undergoes a long series of changes as it defrosts from late winter through spring and into early summer. Summer will arrive at the end of September 2003. This picture is located near 72°S, 181°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04759: Defrosting Richardson Dunes sur le site de la NASA.PIA05119: Gusev Crater
2 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle image shows the crater in which the Mars Exploration Rover, Spirit, is scheduled to land on 4 January 2004 (around 8:35 p.m., 3 January 2004, Pacific Standard Time). The white ellipse marks the approximate location of Spirit's landing zone. Gusev Crater is about 165 km (103 mi) across. The valley that enters Gusev from the south-southeast (bottom/lower right) is named Ma'adim Vallis. The dark areas on the floor of Gusev, when viewed at higher resolution, are found to be surfaces from which dust devils and wind gusts have removed or disrupted the fine, bright dust that otherwise blankets the crater floor. This image, acquired in November 2003, is located near 14.5°S, 184.6°W. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05119: Gusev Crater sur le site de la NASA.PIA04725: Eroded Cratered Highlands
MGS MOC Release No. MOC2-472, 3 September 2003
This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the remains of two former meteor impact craters in northeastern Arabia Terra. The circular mesa toward the northeast (upper left) corner of the image was once a crater that became filled with material. Later, erosion stripped away the surrounding terrain, but left the filled crater behind as a mesa. The larger circular feature in this image is the eroded remains of another meteor crater; its rims and ejecta have been eroded away, and its north/northwest (left/upper left) rim has been completely removed. The processes that have eroded terrain in northeastern Arabia are unknown, but probably, at least, involved deflation by wind. This picture covers an area 3 km (1.9 mi) across and is located near 26.9°N, 301.6°W. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04725: Eroded Cratered Highlands sur le site de la NASA.PIA05165: Challenger Memorial Station, Meridiani Planum, Mars
A composite image reveals the local region surrounding the Challenger Memorial Station. The image is actually an amalgamation of a Mars Global Surveyor's Mars Orbiter Camera image and the third and final picture taken by Opportunity's DIMES camera ( Descent Image Motion Estimation System) during descent. The location of the site is a 20-meter (65.6 foot) wide, 2-meter (6.6 foot) deep crater somewhere in this composite image. The final crew of the space shuttle Challenger was lost when the shuttle suffered an in-flight breakup during launch on Jan. 28, 1986.
Figure 1
Opportunity's Turf
April 8, 2004
This map highlights the past and future stomping grounds of the Mars Exploration Rover Opportunity. "Eagle Crater" is the small crater where the rover landed over two months ago. "Anatolia," named after the Anatolian fault system in Turkey, is the trough the rover is currently investigating. "Endurance" is the large crater the rover will travel toward in coming sols. The underlying image was taken by the camera onboard the Mars Global Surveyor orbiter.
Voir l'image PIA05165: Challenger Memorial Station, Meridiani Planum, Mars sur le site de la NASA.PIA04891: Elysium Mons Wind Streak
MGS MOC Release No. MOC2-556, 26 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak formed behind a meteor impact crater on the lower north flank of the volcano, Elysium Mons. Winds blow down the volcano slope, toward the northeast (toward upper right), causing a tail of uneroded dust to be captured behind the crater. Thin, filamentary dark streaks (resembling pencil scratches in this image) can be seen on the surface of the bright wind streak; these may have formed by disruption of surface dust by passing dust devils. This picture is located near 27.7°N, 212.7°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the left.
Voir l'image PIA04891: Elysium Mons Wind Streak sur le site de la NASA.PIA04722: Martian Gullies
MGS MOC Release No. MOC2-470, 1 September 2003
This July 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) full-resolution (1.5 meters--5 feet--per pixel) image shows a suite of gullies in the wall of a crater near 35.3°S, 76.3°W. The gullies are considered to have formed by downslope transport of water-laden debris, although the exact nature of the fluid is unknown because it is no longer present. This image covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA04722: Martian Gullies sur le site de la NASA.PIA04896: Windblown Sand Dunes
MGS MOC Release No. MOC2-557, 27 November 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes and large ripples in a crater in the Hellespontus region of Mars. The winds that formed these dunes generally blew from the left/lower-left (west/southwest). Unlike the majority of dunes on Earth, sand dunes on Mars are mostly made up of dark, rather than light, grains. This scene is located near 50.3°S, 327.5°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the upper left.
Voir l'image PIA04896: Windblown Sand Dunes sur le site de la NASA.PIA04911: Tithonium Chasma's Sedimentary Rocks
MGS MOC Release No. MOC2-565, 5 December 2003
Exposures of light-toned, layered, sedimentary rocks are common in the deep troughs of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from western Tithonium Chasma. The banding seen here is an eroded expression of layered rock. Sedimentary rocks can be composed of (1) the detritus of older, eroded and weathered rocks, (2) grains produced by explosive volcanism (tephra, also known as volcanic ash), or (3) minerals that were chemically precipitated out of a body of liquid such as water. These outcrops are located near 4.8°S, 89.7°W. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.
Voir l'image PIA04911: Tithonium Chasma's Sedimentary Rocks sur le site de la NASA.PIA05742: Summer South Polar Cap
13 April 2004
The martian south polar residual ice cap is composed mainly of frozen carbon dioxide. Each summer, a little bit of this carbon dioxide sublimes away. Pits grow larger, and mesas get smaller, as this process continues from year to year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of a small portion of the south polar cap as it appeared in mid-summer in January 2004. The dark areas may be places where the frozen carbon dioxide contains impurities, such as dust, or places where sublimation of ice has roughened the surface so that it appears darker because of small shadows cast by irregularities in the roughened surface. The image is located near 86.9°S, 7.6°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05742: Summer South Polar Cap sur le site de la NASA.PIA04674: Warrego Valles
MGS MOC Release No. MOC2-440, 2 August 2003
Warrego Valles is a suite of branching valleys located in the martian southern hemisphere near 43°S, 92°W. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the valleys of this system. They are old and have been partially filled with material that today forms an eroded, rugged texture. Prior to the MGS mission, it had been hoped that MOC would show evidence as to how valleys such as those in the Warrego system formed, but many of the valleys turned out to have been modified by later processes that obscure the original geologic features related to their origin. This image is illuminated from the upper left.
Voir l'image PIA04674: Warrego Valles sur le site de la NASA.PIA05793: Dusty Collapse Pit
19 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a pit formed by collapse on the lower southeast flank of Olympus Mons. The terrain surrounding the pit, and the pit walls and floor, appear to be mantled by fine dust. The image is located near 17.2°N, 138.7°W. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05793: Dusty Collapse Pit sur le site de la NASA.PIA04898: South Polar Layered Slope
MGS MOC Release No. MOC2-559, 29 November 2003
Both the north and south polar regions of Mars exhibit thick deposits of layered sediment. These have been known since the Mariner 9 (1972) and Viking (1976-1980) orbiter missions. The layered deposits are considered to contain a record of climate changes that occurred in the relatively recent martian past, but most of that record will have to wait until some time in the future when a lander or people can go there to study them. Meanwhile, pictures such as this from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) provide opportunities to view the layers where they are exposed on slopes. Here, numerous layers have been exposed by erosion in the south polar region. The picture was obtained in October 2003 and is located near 86.4°S, 112.4°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the upper left.
Voir l'image PIA04898: South Polar Layered Slope sur le site de la NASA.PIA04750: Defrosting Patterns
MGS MOC Release No. MOC2-487, 18 September 2003
This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows patterns created by defrosting processes on the south polar seasonal ice cap. Seasonal cap refers to the part of the polar cap that comes and goes with the seasons, as opposed to the residual cap, which lasts throughout the summer. The area shown here, in summer, will have no frost. This picture was taken during southern spring. As the seasonal frost begins to sublime away, dark cracks form a polygon pattern, and wind blows material to form varied bright and dark streaks. What is unknown is whether the dark streaks consist of sand and silt from beneath the seasonal frost, or whether they, too, consist of frost that has been transformed into coarse-grained particles that can be mobilized by wind. Alternatively, the streaks represent erosion and removal of frost, rather than deposition of granular material. The bright streaks are most likely made of frost--whether they are water ice or carbon dioxide ice remains to be determined. The bulk of the frosted surface shown here is carbon dioxide ice. The image is located near 87.3°S, 192.4°W. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
Voir l'image PIA04750: Defrosting Patterns sur le site de la NASA.PIA04781: Kasei Valles Flow
MGS MOC Release No. MOC2-503, 4 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the lobate fronts of a large flow or series of smaller flow features in Kasei Valles. The rubbly surface of the flow has been interpreted to suggest that this might have been a mud flow, rather than a lava flow, but final determination will someday require a person to visit this landform "in the field." This picture is illuminated from the right and covers an area approximately 8 km (5 miles) wide near 15.7°N, 77.7°W.
Voir l'image PIA04781: Kasei Valles Flow sur le site de la NASA.PIA05739: Marte Valles Crater "Island"
10 April 2004
Marte Valles is an outflow channel system that straddles 180°W longitude between the region south of Cerberus and far northwestern Amazonis. The floor of the Marte valleys have enigmatic platy flow features that some argue are formed by lava, others suggest they are remnants of mud flows. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an island created in the middle of the main Marte Valles channel as fluid---whether lava or mud---flowed past two older meteor impact craters. The craters are located near 21.5°N, 175.3°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05739: Marte Valles Crater "Island" sur le site de la NASA.PIA04757: Ancient Valley
MGS MOC Release No. MOC2-491, 22 September 2003
Auqakuh Vallis is an ancient valley system that might have once been a conduit for liquid water flowing north, across northeastern Arabia Terra, toward the Nilosyrtis region. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the Auqakuh Vallis system. The valley was cut into layered bedrock. It was once much deeper than today, but much of the surrounding materials have been eroded away. Windblown sediments now cover the floor of the valley, a reflection of the parched conditions of the modern martian environment. This picture is located near 29.1°N, 299.6°W, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04757: Ancient Valley sur le site de la NASA.PIA05794: Buttes in Memnonia
20 April 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows three small buttes in the Memnonia Sulci region of Mars near 10.5°S, 176.1°W. The buttes are remnants of formerly more extensive layered rock that once covered the region. The larger butte has several dark slope streaks formed by downslope movement (landsliding/avalanching) of dust. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.
Voir l'image PIA05794: Buttes in Memnonia sur le site de la NASA.PIA05820: Early Autumn Dust Storm
27 April 2004
Sporadic, localized dust storms are common at high southern latitudes in early autumn. The most recent autumn for the southern hemisphere began on 5 March 2004. This late March 2004 narrow angle camera image was acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) as it passed over a crater in southern Noachis Terra near 59.6°S, 2.7°W. The northern portion of the image is clear enough that details such as large boulders or small knobs can be seen. The rest of the image, however, shows billowy clouds of dust being raised from the surface. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05820: Early Autumn Dust Storm sur le site de la NASA.PIA04746: Boulders on Phobos
MGS MOC Release No. MOC2-485, 16 September 2003
In 1998, the Mars Global Surveyor (MGS) spacecraft made four passes by the innermost of the two martian satellites, Phobos. The fourth pass, made just over 5 years ago on 12 September 1998, offered the Mars Orbiter Camera (MOC) the opportunity to acquire the highest resolution images of the moon, ever. This wonderful 5-year-old picture highlights the surface of Phobos. Several large boulders can be seen, including a very large one near the center that is about 85 meters (~280 feet) in diameter. Most of the boulders may have been ejected from the largest impact crater on Phobos, Stickney. Sunlight illuminates the scene from the left/lower left.
Voir l'image PIA04746: Boulders on Phobos sur le site de la NASA.PIA05915: Martian Gullies
8 May 2004
This March 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a gullied crater wall at southern mid-latitude near 35.5°S, 223.0°W. Formation of such gullies might have involved flowing liquid water. The Mars science community has been debating, since they were first reported in June 2000, whether such gullies were carved by water, carbon dioxide, or perhaps formed in completely dry, granular material without the influence of a fluid. The scientists have also debated whether the water--if it was water--started out in the form of ground ice, a snow pack, or liquid groundwater. Since June 2000, many hundreds of new gully locations--and tens of thousands of individual gullies--have been identified. Their relative youth suggests to some the possibility that Mars today has water or ice within less than 1 kilometer of the surface--a depth that may be readily accessible to future explorers. This picture is illuminated by sunlight from the upper left and covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05915: Martian Gullies sur le site de la NASA.PIA05022: Terby Sedimentary Rocks
27 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rock outcrops in Terby Crater, located near 27.7°S, 285.4°W. The layered sediments in Terby are several kilometers thick, attesting to a long history of deposition in this ancient basin. The picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05022: Terby Sedimentary Rocks sur le site de la NASA.PIA04662: Outcrop In Juventae Chasma
MGS MOC Release No. MOC2-433, 26 July 2003
Light-toned sedimentary rock outcrops are common on the floors of the chasms associated with the Valles Marineris system and neighboring outflow channels. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an outcrop of sedimentary rock in Juventae Chasma near 4.1°S, 62.0°W. The scene is illuminated by sunlight from the left.
Voir l'image PIA04662: Outcrop In Juventae Chasma sur le site de la NASA.PIA05443: South Polar Layer Remnants
24 February 2004
The thin, dark, angular mesas in depressions in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image are remnants of a layer of material that has been largely stripped away from the region. The picture is located in the south polar region near 78.1°S, 272.2°W. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05443: South Polar Layer Remnants sur le site de la NASA.PIA04665: Cliff in Terby Crater
MGS MOC Release No. MOC2-436, 29 July 2003
Terby Crater was once filled with layered, sedimentary rock. Over time, these materials have been eroded to form a dazzling array of cliffs and layered outcrops. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a layered cliff facing toward the northwest (toward upper left). Dark debris has slid down the west-facing slopes of the cliff. A visitor to Terby Crater would be greeted by vistas reminiscent of some of the national parks in the southwestern United States. This March 2003 picture is located near 27.7°S, 285.5°W; it is illuminated by sunlight from the upper left. The picture covers an area 3 km (1.9 mi) across.
Voir l'image PIA04665: Cliff in Terby Crater sur le site de la NASA.PIA05025: Fretted Terrain Valley Floor
30 December 2003
This December 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lineated textures on the floor of a valley in the Deuteronilus region of Mars. Deuteronilus, and neighboring Protonilus and Nilosyrtis, have been known since the Mariner 9 mission as regions of "fretted terrain." In this context, "fretted" does not mean "worried," it means "eroded." The fretted terrains of Mars are regions along the boundary between cratered highlands and northern lowland plains that have been broken-down into mesas, buttes, and valleys. On the floors of some of these valleys occurs a distinctive lineated and pitted texture--like the example shown here. The cause of the textures is not known, although for decades some scientists have speculated that ice is involved. While this is possible, it is far from a demonstrated fact. This picture is located near 40.1°N, 335.1°W, and covers an area approximately 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05025: Fretted Terrain Valley Floor sur le site de la NASA.PIA05444: Gullied Martian Slope
25 February 2004
Gullies cut material that mantles the slopes of a deep pit within a crater in Noachis Terra near 50.1°S, 356.4°W in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Gully channels seem to originate at layer outcrops in the upper walls of the pit. These may have formed by downslope movement of liquid water mixed with debris in the geologically recent martian past. Similar gullies are found throughout much of the martian middle and high latitudes. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05444: Gullied Martian Slope sur le site de la NASA.PIA04790: Arabian Slope Streaks
MGS MOC Release No. MOC2-508, 9 October 2003
Arabia Terra is a vast, heavily cratered region in the martian northern hemisphere. Much of Arabia Terra is thickly blanketed by dust. From time to time, on steep slopes, the dust will avalanche or slide downhill, creating a streak. The majority of slope streaks are darker than their surroundings, but not all of them are dark. In Arabia, it is common to find bright and dark slope streaks, and to find them together. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example, taken from a crater near 10.5°N, 318.4°W. Why some streaks are bright and others are dark is not yet known. This picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.
Voir l'image PIA04790: Arabian Slope Streaks sur le site de la NASA.PIA05912: Martian "Brain"
5 May 2004
Most middle-latitude craters on Mars have strange landforms on their floors. Often, the floors have pitted and convoluted features that lack simple explanation. In this case, the central part of the crater floor shown in this 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image bears some resemblance to the folded nature of a brain. Or not. It depends upon the "eye of the beholder," perhaps. The light-toned "ring" around the "brain" feature is more easily explained--windblown ripples and dunes. The crater occurs near 33.1°S, 91.2°W, and is illuminated from the upper left. The picture covers an area about 3 km (1.9 mi) across.
Voir l'image PIA05912: Martian "Brain" sur le site de la NASA.PIA05264: Sedimentary Rocks of Aram Chaos
4 February 2004
Aram Chaos is a large meteor impact crater that was nearly filled with sediment. Over time, this sediment was hardened to form sedimentary rock. Today, much of the eastern half of the crater has exposures of light-toned sedimentary rock, such as the outcrops shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. The picture is located near 2.0°N, 20.3°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
Voir l'image PIA05264: Sedimentary Rocks of Aram Chaos sur le site de la NASA.PIA04856: Sand Dunes in Hellas
MGS MOC Release No. MOC2-537, 7 November 2003
The smooth, rounded mounds in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture are sand dunes. The scene is located in southern Hellas Planitia and was acquired in mid-southern autumn, the ideal time of year for Hellas imaging. Sunlight illuminates the scene from the upper left. These dunes are located near 49.1°S, 292.6°W. The picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA04856: Sand Dunes in Hellas sur le site de la NASA.PIA04733: Brazos Valles Dunes
MGS MOC Release No. MOC2-476, 7 September 2003
Nearly six years ago, when the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was taking some of its earliest high resolution images of the planet, an area of light-toned, wind-blown, ripple-like bedforms was spotted in the Brazos Valles near Schiaparelli Basin. These features were highlighted on November 10, 1997, in
"Valley and Surrounding Terrain Adjacent to Schiaparelli Crater."This picture shows a close-up view of some of the light-toned bedforms first visible in that early MOC image. This picture was acquired at full resolution (1.5 meters--5 feet--per pixel). The image shows that the light-toned bedforms are not fresh, young features; they are jagged and roughened, as if they have been indurated (cemented) and then somewhat eroded by wind. This picture is located near 5.4°S, 340.6°W; it covers an area 1.1 km (0.7 mi) across. The scene is illuminated by sunlight from the left.
Voir l'image PIA04733: Brazos Valles Dunes sur le site de la NASA.PIA04887: Iberus Vallis Troughs
MGS MOC Release No. MOC2-553, 23 November 2003
Iberus Vallis is a trough system located radial to and southeast of the martian volcano, Elysium Mons. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in October 2003, shows some of the valleys of this region; they are cut into what is presumably (at least near the top) volcanic rock. The dark dots and specks on the valley floors are large boulders that have been shed from the slopes. This picture is located near 21.6°N, 208.3°W. The image shows an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the lower left.
Voir l'image PIA04887: Iberus Vallis Troughs sur le site de la NASA.PIA05844: Barchan Dunes
28 April 2004
One of the simplest forms a sand dune can take is the barchan. The term, apparently, comes from the Arabic word for crescent-shaped dunes. They form in areas with a single dominant wind direction that are also not overly-abundant in sand. The barchan dunes shown here were imaged in March 2004 by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) as it passed over a crater in western Arabia Terra near 21.1°N, 17.6°W. The horns and steep slope on each dune, known as the slip face, point toward the south, indicating prevailing winds from the north (top). The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA05844: Barchan Dunes sur le site de la NASA.PIA05340: Small Landslide in Kasei
21 February 2004
The finger-shaped lobe just right of center in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is the deposit of a small landslide that came down a dark, layered slope. Landslides are common on Mars in areas of steep topography; this one is located in the Kasei Valles region near 23.9°N, 67.1°W. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05340: Small Landslide in Kasei sur le site de la NASA.PIA04972: South Polar Mesas
MGS MOC Release No. MOC2-573, 13 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows mesas--the eroded remnants of a former layer or group of layers--in the south polar region of Mars. The circular feature at the top of the image is an old meteor impact crater that has been somewhat covered by younger materials; a remnant of the layer that comprises the mesas is also found on the floor of this crater. The image is located near 79.3°S, 299.0°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates this scene from the upper left.
Voir l'image PIA04972: South Polar Mesas sur le site de la NASA.PIA04799: Dust-Raising Event
MGS MOC Release No. MOC2-515, 16 October 2003
The bright feature near the center-left in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture is a plume of dust being raised by wind on a slope in far eastern Arabia Terra on February 18, 2001, near 2 p.m. (14:00) local time. The dark feature immediately below and to the right of the bright plume is the shadow being cast by this brief, dust-raising event. The picture is located near 3.5°N, 306.6°W, and covers an area 3 km (1.9 mi) wide. The shadow indicates that this scene is illuminated by sunlight from the upper left.
Voir l'image PIA04799: Dust-Raising Event sur le site de la NASA.PIA04975: Peering into a Cerberus Fossae Trough
MGS MOC Release No. MOC2-576, 16 December 2003
The Cerberus Fossae are a series of long troughs and cracks that run southeastward from the Elysium volcanic region. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a view looking down into two of the troughs. Dark specks in the troughs are boulders that have come loose from the walls and rolled to a stop on the floors. In recent years, some Mars scientists have speculated that the Cerberus Fossae troughs were the source of volcanic eruptions, and perhaps also the source of water that produced catastrophic floods. However, no evidence for either process is found at this particular location. The picture is located near 10.1°N, 202.0°W. The image covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA04975: Peering into a Cerberus Fossae Trough sur le site de la NASA.PIA05263: Large Bright Ripples
3 February 2004
Wind is the chief agent of change on Mars today. Wind blows dust and it can move coarser sediment such as sand and silt. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows bright ripples or small dunes on the floors of troughs northeast of Isidis Planitia near 31.1°N, 244.6°W. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
Voir l'image PIA05263: Large Bright Ripples sur le site de la NASA.PIA04734: Arabia's Auqakuh Vallis
MGS MOC Release No. MOC2-477, 8 September 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of southern Auqakuh Vallis in northeastern Arabia Terra. The floor of this ancient valley--which might have been carved by a liquid such as water--is today covered by large, windblown, ripple-like bedforms. The terrain surrounding the valley has been eroded such that only remnants of former craters and layered bedrock remain. The valley was once much deeper, but material of hundreds, if not thousands, of meters thickness has been removed. This picture is located near 28.9°N, 299.9°W; it covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
Voir l'image PIA04734: Arabia's Auqakuh Vallis sur le site de la NASA.PIA04880: Volcano Near Pavonis Mons
MGS MOC Release No. MOC2-549, 19 November 2003
The volcanic plains to the east, southeast, and south of the giant Tharsis volcano, Pavonis Mons, are dotted by dozens of small volcanoes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 2.1°S, 109.1°W. The elongate depression in the lower left (southwest) quarter of the image is the collapsed vent area for this small, unnamed volcano. A slightly sinuous, leveed channel runs from the depression toward the upper right (north-northeast); this is the trace of a collapsed lava tube. The entire scene has been mantled by dust, such that none of the original volcanic rocks are exposed--except minor occurrences on the steepest slopes in the vent area. The scene is 3 km (1.9 mi) wide and illuminated by sunlight from the left/upper left.
Voir l'image PIA04880: Volcano Near Pavonis Mons sur le site de la NASA.PIA04864: Dust Devil Art
MGS MOC Release No. MOC2-541, 11 November 2003
In some regions of Mars, dust devils create streaks by disrupting or removing thin coatings of fine, bright dust from the surface. This summertime view of terrain in southern Noachis Terra, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), provides an example. Streak patterns such as these are commonly created during the spring and summer in the southern hemisphere; in autumn and winter they are often erased--perhaps by deposition of a new coating of dust--and then a completely different pattern is formed the following spring and summer. This image is located near 59.6°S, 328.8°W. The picture is 3 km (1.9 mi) wide and illuminated by sunlight from the upper left.
Voir l'image PIA04864: Dust Devil Art sur le site de la NASA.PIA04688: Peridier Dune Field
MGS MOC Release No. MOC2-454, 16 August 2003
Four days ago, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Picture of the Day featured a MOC wide angle view of
Peridier Crater and the dark feature on its southwestern floor. Today's Picture of the Day shows a MOC narrow angle view of a portion of the dark area in southwest Peridier Crater. Some of the dark material in this crater resolves at higher resolution into a field of small sand dunes. The dune slip faces--the steepest slopes on the dunes-face toward the southwest (lower left), indicating that the dominant winds that have shaped these dunes blow from the northeast. The picture has a resolution of about 1.8 m (5.9 ft) per pixel; it covers an area only 1.1 km (0.7 mi) wide. The image is somewhat grainy because it was taken through a late northern summer hazy atmosphere in April 2003. The image is located in southwest Peridier Crater near 25.3°N, 276.5° W. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04688: Peridier Dune Field sur le site de la NASA.PIA05019: Isidis Planitia
24 December 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small portion of the vast Isidis Planitia, the region in which the Beagle 2 is scheduled to land on 25 December 2003 (GMT; it will be the evening of 24 December 2003 in the U.S.). Much of Isidis Planitia has low hills and mounds like those shown here. Many of these are remnants of a layer (or group of sub-resolution layers) that once more extensively covered Isidis Planitia, but was later stripped away, revealing previously-buried meteor impact craters. The light-toned ridges and somewhat squiggly features are windblown dunes. This picture is located around 10.7°N, 268.6°W, which is in the vicinity of the projected Beagle 2 landing zone. The picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left/lower left.
Voir l'image PIA05019: Isidis Planitia sur le site de la NASA.PIA05527: Olympian Lava Channels
29 February 2004
Flowing lava can make leveed channels--that is, channels with raised-rimmed walls. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the lower north flank of the giant volcano, Olympus Mons. The channels today are filled with a blanket of dust. The image is located near 23.0°N, 135.9°W. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.
Voir l'image PIA05527: Olympian Lava Channels sur le site de la NASA.PIA05280: Wind-Streaked Slopes
6 February 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows very heavily wind-streaked slopes in an area near southern Claritas Fossae. Wind rushing down slopes toward the lower left has moved fine sediment to create these patterns. This is located near 25.3°S, 109.7°W, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05280: Wind-Streaked Slopes sur le site de la NASA.PIA05251: Mars Exploration Rover (MER-B) Opportunity Landing Site
Mosaic (Click on image for larger view)
Wide Angle View (Click on image for larger view)
Narrow Angle View (Click on image for larger view)
24 January 2004
The second Mars Exploration Rover (MER-B), Opportunity, is set to land on Mars around 9:05 p.m. Pacific Standard Time today, 24 January 2004 (25 January 2004 UTC). Above are shown three perspectives on the Opportunity landing site, which is an ellipse in Meridiani Planum approximately 87 km (54 mi) long by 11 km (6.8 mi) wide. All images are oriented with north up and east to the right. The lander will be coming through the atmosphere from the west/southwest, roughly following the long axis of the ellipse. It is most likely to touch down somewhere near the center of the ellipse.
The first image (top) is a mosaic of MGS MOC and Mars Odyssey Thermal Emission Imaging System visible images (THEMIS-VIS). The THEMIS-VIS instrument provides pictures with a spatial resolution of 18 meters per pixel (~59 ft/pixel); the MOC images used in the mosaic have resolutions ranging from 1.4 m/pixel to 12 m/pixel. A total of 15 THEMIS-VIS images were used to form the background, on which 61 MOC high resolution images were mosaiced. These data were acquired over a period spanning parts of 3 Mars years between April 1999 through January 2004. These pictures were acquired not only in different years, but in different seasons, so the illumination angle, overall brightness, and patterns of ephemeral windblown dust and, in some cases, dark dust devil streaks, are different from image to image within the mosaic.
The second image (middle) is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle view obtained in November 2003 as part of an on-going effort to monitor the weather at the landing site. The wide angle view provides a sense of the regional context. The third image (bottom) is a 1.8 m/pixel (6 ft/pixel) view near the center of the landing ellipse. It was also acquired by MOC in November 2003, and covers an area 3 km (1.9 mi) wide. The light-toned, somewhat circular features are believed to be either the location of ancient, buried, nearly-filled meteor impact craters or the eroded remains of craters that formed in bedrock that has long since been removed from the region.
The Opportunity landing site in Meridiani Planum was selected to provide access, it is hoped, to materials bearing the iron oxide mineral, hematite. Hematite was detected in this region by the Thermal Emission Spectrometer (TES) on MGS. This mineral is suspected of providing a clue that liquid water may have once played a role in the region. The dark-toned materials of Meridiani Planum cover a lighter-toned substrate that may consist of layered rock. Small ridges have formed in the dark material in some parts of the landing ellipse, but no one will know until the first images are returned, exactly what features will be present at the Opportunity site. One thing is certain: no previous Mars lander has ever gone to a setting like Meridiani Planum. The landscape is almost certain to be different than the Viking 1, Viking 2, Mars Pathfinder, and Spirit sites.
Sunlight illuminates the wide and narrow angle views, and each image in the mosaic, from the left.
The THEMIS instrument is operated by a team at Arizona State University; the
THEMIS-VIS camera was built by Malin Space Science Systems (MSSS), which also operates the MGS MOC. Opportunity will land in the mid-afternoon, local time, on Mars. At the same time, Mars Global Surveyor will pass over the site and listen for a transmission of Opportunity's entry, descent, and landing data. These data will be relayed back to Earth by the MOC. For more information about the Mars Exploration Rovers, visit
NASA/JPL's Mars Exploration Program Web site. For more information about the work that Malin Space Science Systems and MGS MOC are doing in support of the rover missions, see:
http://www.msss.com/mer_mission/. For information about how MSSS will use this mosaic of the landing site to help find Opportunity after it touches down, see
Finding MERs. MER landing site weather reports are located at:
http://www.msss.com/mars_images/moc/mer_weather/. Voir l'image PIA05251: Mars Exploration Rover (MER-B) Opportunity Landing Site sur le site de la NASA.PIA05529: Mesa in Capri Chasma
2 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle picture shows light-toned, sedimentary rock outcrops forming the walls of a dark-topped mesa in Capri Chasma. Capri Chasma is at the east end of the vast Valles Marineris trough system. This image is located near 12.8°S, 48.1°W. This view covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
Voir l'image PIA05529: Mesa in Capri Chasma sur le site de la NASA.PIA04681: Large, Windblown Ripples
MGS MOC Release No. MOC2-447, 9 August 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the plethora of large, windblown ripples (or small dunes) among wind-sculpted sedimentary rocks in eastern Candor Chasma. Candor Chasma is one of the troughs of the Valles Marineris, a system of chasms that would stretch all the way across North America if it were on Earth. This picture is located near 7.9°S, 64.9°W. Sunlight illuminates the scene from the left/upper left.
Voir l'image PIA04681: Large, Windblown Ripples sur le site de la NASA.PIA04650: Small Volcano
MGS MOC Release No. MOC2-425, 18 July 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image, acquired 13 July 2003, shows a small, dust-covered volcano on the plains east of Pavonis Mons. The floor of the caldera--the elliptical depression at the summit of the volcano--has a few windblown ripples on it. The ripples and thick dust mantle, together with the small impact craters on its surface, indicate that the volcano erupted some time ago. There has been no activity at this volcano in geologically recent times. This image covers an area 3 km wide by 6.8 km (1.9 mi by 4.2 mi); the aspect ratio is 1 across by 1.5 down. The volcano is located near 1.6°S, 105.7°W; sunlight illuminates the scene from the left.
Voir l'image PIA04650: Small Volcano sur le site de la NASA.
PIA04774: Olympica Fossae
MGS MOC Release No. MOC2-500, 1 October 2003
This 500th Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) captioned release shows some of the complex flow and channel features of the Olympica Fossae region in northern Tharsis. The story of the Olympica Fossae is still emerging and continues to be puzzling. There is evidence in the Olympica Fossae channels that a fluid with the physical properties of water may have been involved in creating some of the erosional forms, but there are also flow features suggestive of lava or mud in the region. Regardless, the Olympica Fossae almost always yield a very pretty and interesting MOC high resolution image. This picture is located near 24.5°N, 115.4°W. The area shown is 3 km (1.9 mi) wide and illuminated by sunlight from the lower left.
Voir l'image PIA04774: Olympica Fossae sur le site de la NASA.PIA05693: Dark Sand Dunes
18 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of low-albedo (i.e., dark) sand dunes in a crater in Noachis Terra. Dunes on Earth are usually light while those on Mars are usually dark. This contrast results from a difference in the mineral composition. Earth dunes often contain abundant quartz, which appears light, while martian dunes typically contain minerals and rock fragments abundant in iron- and magnesium-rich minerals, which are usually dark. This dune field is located near 41.7°S, 319.8°W. The steeper slopes on these dunes, known as slip faces, point toward the lower left (southwest), indicating the dominant winds come from the northeast (upper right). This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
Voir l'image PIA05693: Dark Sand Dunes sur le site de la NASA.PIA05642: Crater in Elysium Planitia
15 March 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an impact crater in northern Elysium Planitia near 31.3°N, 236.8°W. Layered rock is exposed in the upper crater walls. Light-toned ripples or small dunes can be seen in the crater, on its ejecta blanket, and on the surrounding plains. This February 2004 picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Voir l'image PIA05642: Crater in Elysium Planitia sur le site de la NASA.PIA04811: Rippled Mars
MGS MOC Release No. MOC2-524, 25 October 2003
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a rugged surface southwest of Huygens Basin that is covered by large windblown ripples or small dunes. Their orientations indicate that the responsible winds came from either the northwest (upper left) or southeast (lower right), or both. The more complex ripple patterns within the two large craters result from local topographic influences on the wind. This area is located near 20.1°S, 307.3°W. The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
Voir l'image PIA04811: Rippled Mars sur le site de la NASA.PIA05694: Carbon Dioxide Landforms
19 March 2004
The martian south polar residual ice cap is mostly made of frozen carbon dioxide. There is no place on Earth that a person can go to see the landforms that would be produced by erosion and sublimation of hundreds or thousands of cubic kilometers of carbon dioxide. Thus, the south polar cap of Mars is as alien as alien can get. This image, acquired in February 2004 by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), shows how the cap appears in summer as carbon dioxide is subliming away, creating a wild pattern of pits, mesas, and buttes. Darker surfaces may be areas where the ice contains impurities, such as dust, or where the surface has been roughened by the removal of ice. This image is located near 86.3°S, 0.8°W. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the top/upper left.
Voir l'image PIA05694: Carbon Dioxide Landforms sur le site de la NASA.PIA04773: Valley Near Phlegra Dorsa
MGS MOC Release No. MOC2-499c, 30 September 2003
This February 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a valley in the Phlegra Dorsa region of Mars near 26.3°N, 186.2°W. The valley might have formed by flowing water or lava, but very little is yet known about this valley--where is its source? where does it end? The valley is intimately associated with lava flows, and might therefore result from volcanism rather than water. The fluid responsible for the valley moved from the lower left (southwest) toward the upper right (northeast). The picture covers an area 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left.
Voir l'image PIA04773: Valley Near Phlegra Dorsa sur le site de la NASA.PIA05258: Lonely Butte
14 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a lonely, light-toned butte composed of sedimentary rock in northern Sinus Meridiani. The dark landscape that surrounds the butte was once covered by the same rocks that make up this lonely remnant.
Location near: 2.5°N, 4.2°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
Voir l'image PIA05258: Lonely Butte sur le site de la NASA.PIA04686: Dust-Raising Event in Noachis
MGS MOC Release No. MOC2-452, 14 August 2003
Mars is a desert world. Every day, somewhere on the planet, wind is picking up dust and moving it around. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red camera image shows a portion of Noachis Terra on a winter afternoon as great gusts of wind lifted dust from a variety of surfaces all across the region. At the time the picture was acquired, winds were blowing from the northwest (left/upper left) toward the southeast (lower right). Located near 38°S, 330°W, this image covers an area approximately 252 km (158 mi) wide. Sunlight illuminates the scene from the upper left; some of the dust plumes can be seen to cast shadows toward the bottom/lower right (south/southeast).
Voir l'image PIA04686: Dust-Raising Event in Noachis sur le site de la NASA.PIA04657: Clouds Near Icaria Planum
MGS MOC Release No. MOC2-430, 23 July 2003
Like Earth, the martian atmosphere has clouds. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows small, puffy, water ice clouds over a cratered terrain near Icaria Planum. Illuminated by sunlight from the upper left, these small clouds cast shadows on the ground toward the lower right. This center of this image is near 31°S, 113°W. The picture was taken using MOC's blue wide angle camera.
Voir l'image PIA04657: Clouds Near Icaria Planum sur le site de la NASA. 
