6 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an odd area of the south polar region that has sets of fine, nearly parallel lines running from the northeast (upper right) toward southwest (lower left) and a darker, wider set of cracks with a major trend running almost perpendicular to the finer lines. The appearance of these features is enhanced by seasonal frost. Dark areas have no frost, bright areas still have frozen carbon dioxide ice. In summer, the ice would be gone and the cracks and lines less obvious when viewed from orbit. Although unknown, wind might be responsible for forming the fine set of lines, and perhaps freeze-thaw cycles of ground ice or structural deformation would have contributed to formation of the wider cracks. The image is located near 85.0°S, 324.0°W, and covers an area about 1.5 km (nearly 1 mi) across. The scene is illuminated by sunlight from the upper left.
17 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, ripple-like, windblown bedforms and ridges with dark talus accumulations on their slopes in the western portion of the vast Valles Marineris trough system. These features are located near Oudemans Crater around 7.6°S, 91.2°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the upper left.
15 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a ripple-covered valley floor in the Hyblaeus Fossae region. Winds blowing up and down the length of the valley have helped to concentrate windblown grains to form these large, megaripples.
Location near: 26.3°N, 225.1°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
3 July 2004
The Sulci Gordii are a grouping of ridges -- almost like small, rocky mountains -- located east of the giant volcano, Olympus Mons. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 3 km (1.9 mi) -wide portion of the Sulci Gordii region. The rugged hills and mountains have been mantled by a blanket of fine dust. Ripple-like dunes in the troughs between each hill or mountain have also been covered with dust, indicating that they are inactive in the present martian environment. This image is located near 21.2°N, 124.2°W. Sunlight illuminates the scene from the lower left.
After NASA's Mars Exploration Rover Opportunity finishes examining its heat shield, the rover team plans to direct Opportunity southward toward a round feature dubbed "Vostok," about 1.2 kilometers (three-fourths of a mile) away. The plan is to check out small craters along the way.
This image is from the Mars Orbiter Camera aboard NASA's Mars Global Surveyor. North is up, and the big circle at the top is "Endurance Crater."
21 December 2004
Slopes in the north polar region of Mars exhibit outcroppings of layered material. No one knows the composition of the layers, but the uppermost layers of are thought to be a mixture of dust and ice in some proportion. Lower layers in the north polar region are thought to include sand. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a late northern spring view of a slope on which are exposed some of the upper layers in the north polar region. Bright surfaces in this image are covered by frost. The image is located near 81.5°N, 340.6°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
4 July 2004
This April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small dune field in southeastern Hellas Planitia near 41.4°S, 275.6°W. The image covers an area about 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.
9 September 2004
Northeastern Arabia Terra is a heavily eroded portion of the martian cratered highlands. Layered rock, containing filled and buried valleys and ancient impact craters, has been eroded such that these once-buried features are now partially exposed at the martian surface. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of a field of circular and somewhat circular features that once were impact craters that were subsequently filled, buried, then exhumed to form the patterns exhibited here. The image is located near 25.6°N, 290.2°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows an inverted channel running down, through a valley in the Memnonia Sulci region of Mars. The original channel is gone, as are the rocks through which it cut. The channel floor and/or the material that filled the channel was more resistant to erosion, and thus left standing high as a ridge. Inverted channels and valleys are common on Mars. Many old valley networks have been filled, buried, and in some cases, exhumed and inverted, all across the planet.
Location near: 11.4°S, 174.4°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
18 October 2004
The best time of year to obtain images of the floor of the vast Hellas Planitia impact basin occurs in mid to late southern autumn. At that time of year, the atmosphere over this deep basin is clear and the solar illumination conditions are ideal. Hellas was in this ideal period during July-September 2004. This August 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the eroded floor of a portion of the basin. Hellas has some of the lowest elevations on the planet. This image is located near 39.3°S, 302.8°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the upper left.
19 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded remnants of layered sedimentary rock in northern Sinus Meridiani. The layering is best seen in the circular feature at the center/right, which is an old meteor impact crater that was once filled and buried beneath the sedimentary rocks, then later exhumed and eroded to its present state. All of the sedimentary rocks exposed in this portion of northern Sinus Meridiani are probably older than the rocks in central Sinus Meridiani that have been examined this year by the Mars Exploration Rover, Opportunity. Like the rocks visited by the rover, these, too, may contain detailed clues regarding a wetter Mars in the distant past. These landforms are located near 6.0°N, 2.0°W. The image covers an area approximately 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left/lower left.
20 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes and layered rock outcrops in Rabe Crater, located near 43.8°S, 325.1°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.
8 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows gullies formed in the terraced wall of an impact crater on the floor of a larger crater near 39.1°S, 200.7°W. Gullies such as these are fairly common in craters and depressions at southern middle latitudes. They also occur in some areas at northern middle latitudes and in both polar regions. They may have formed by liquid water, or not--the Mars science community is still debating and discussing the issue. This picture covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
15 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies running down a slope on the side of a mesa in a pit in the south polar region of Mars. The dark material in this scene is windblown sand. These landforms are located near 70.9°S, 357.3°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
23 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes in the martian north polar region in mid-spring, July 2004. In summer, the dunes will be dark. As they defrost, dark spots form on their surfaces. This image is located near 82.8°N, 219.6°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the lower left.
11 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows portions of two of the Cerberus Fossae troughs, their dark-toned interiors, and dark wind streaks formed from material blowing out of the troughs. The wind streaks indicate winds that blew from the northeast (upper right) toward the southwest (lower left). The crust of Mars expanded and split to form the troughs. These features are located near 6.6°N, 187.2°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
1 November 2004
The upper right (northeast) quarter of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a concentrated field of small impact craters. The features form a broad line running approximately diagonal from northwest toward southeast. These craters pocked windblown ripples as well as the smooth-surfaced terrain. These are secondary craters. That is, they formed second, as the result of a larger impact, probably within a hundred kilometers or so of this site. Secondary craters form from impact of the debris kicked-up by the larger impact event. Instead of rocks from space (like a meteor), these were formed by rocks from a nearby place on Mars. This image is located near 29.7°S, 249.0°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
05 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows large, low albedo (dark) sand dunes in Kaiser Crater near 47.2°S, 340.4°W. The dunes are--ever so slowly--moving east to west (right to left) as sand avalanches down the steeper, slip face slopes of each. Avalanching sand in the Kaiser dune field has left deep scars on these slopes, suggesting that the sand is not loose but is instead weakly cemented. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
16 May 2004
This full-resolution (1.5 m/pixel; 5 ft/pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies on a crater wall in northern Noachis Terra. The gullies might have formed by the seepage of martian groundwater or melting of ice. However, the Mars science community is still studying this topic and no consensus has yet emerged as to whether such gullies could have formed without water. These gullies are located near 32.1°S, 12.9°W. The 300 meter scale bar also equals 328 yards (984 feet). The picture is illuminated by sunlight from the left/upper left.
20 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), image shows exposures of finely-bedded sedimentary rocks in western Melas Chasma, part of the vast Valles Marineris trough system. Rocks similar to these occur in neighboring west Candor Chasma, as well. The picture is located near 9.1°S, 74.5°W, and covers an area about 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left/upper left.
2 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a circular mesa and layered materials that are partially-exposed from beneath a thick, dark mantle in the Aureum Chaos region of Mars. The features are part of a much larger circular form (bigger than the image shown here) that marks the location of a crater that was filled with light-toned sedimentary rock, buried, and then later re-exposed when the upper crust of Mars broke apart in this region to form buttes and mesas of "chaotic terrain." The circular mesa in this image might also be the location of a formerly filled and buried crater. This image is located near 4.0°S, 26.9°W. It covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left/upper left.
19 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the mountains that make up the central peak region of Hale Crater, located near 35.8°S, 36.5°W. Dark, smooth-surfaced sand dunes are seen to be climbing up the mountainous slopes. The central peak of a crater consists of rock brought up during the impact from below the crater floor. This autumn image is illuminated from the upper left and covers an area approximately 3 km (1.9 mi) across.
28 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes on the floor of a crater in Noachis Terra. The picture was acquired in early southern autumn in March 2004; it is located near 52.4°S, 336.9°W. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
04 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rock outcrops exposed by erosion in southern Melas Chasma, one of the major Valles Marineris troughs. Such outcrops are common in southern Melas; they resemble the rock outcrops seen in some of the chaotic terrains and other Valles Marineris chasms. This image is located near 11.9°S, 74.6°W, and is about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
7 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an eroded landscape occurring west of Sinus Meridiani, the region in which the Mars Exploration Rover, Opportunity, landed nearly a year ago. The bedrock at this location is buried beneath a mantle of dust, sand, and granules, but remnants of younger layers of bedrock now stand high in the form of buttes in the lower right quarter of the image. The two circular mesas were once meteor impact craters. They were filled, buried, and fossilized within the rock, then later exhumed. This scene is located near 1.5°N, 6.2°W. The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the lower left.
19 June 2004
Exposures of layered, sedimentary rock are common on Mars. From the rock outcrops examined by the Mars Exploration Rover, Opportunity, in Meridiani Planum to the sequence in Gale Crater's central mound that is twice the thickness of of the sedimentary rocks exposed by Arizona's Grand Canyon, Mars presents a world of sediment to study. This unusual example, imaged by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), shows eroded layer outcrops in a crater in Terra Tyrrhena near 15.4°S, 270.5°W. Sedimentary rocks provide a record of past climates and events. Perhaps someday the story told by the rocks in this image will be known via careful field work. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left.
10 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of an outflow channel system located in the Zephyria region, south of Cerberus, from which vast quantities of rough-surfaced material flowed. The channel system has no name and was not known prior to the MGS mission. The material that flowed through this system may have been extremely fluid lava, or it may have been water-rich mud. Research by members of the Mars science community regarding the nature and origin of flow materials in the Cerberus, Zephyria, and Marte Vallis regions of Mars is on-going. This image is located near 4.6°N, 204.1°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.
4 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cracked plain in western Utopia Planitia. The three circular crack patterns indicate the location of three buried meteor impact craters. These landforms are located near 41.9°N, 275.9°W. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this scene from the lower left.
25 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small segment of a martian valley located near 0.5°N, 246.4°W. The valley floor is covered by a plethora of large, windblown ripples. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
21 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark slope streaks coming off of rugged hills in the Lycus Sulci region, north of the Olympus Mons volcano. These slopes are mantled with fine, bright dust. From time to time, the dust will avalanche down a slope, forming a slope streak. The behavior of this dry, granular material can be somewhat fluid-like. New slope streaks can form at any time and, for an area the size of that shown here, may form at a rate of one per Mars year (687 Earth days). Naturally, some scientists have suggested that water plays a role in forming these streaks, but, in general, Mars is drier than the driest deserts on Earth and these streaks are contemporary features that occur in the dustiest regions of the planet. The image is located near 29.8°N, 133.4°W, and covers an area about 3 km (1.9 mi) across. The picture is illuminated by sunlight from the lower left.
6 March 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the surface of lava flows in eastern Daedalia Planum.
Location near: 19.8°S, 118.8°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
25 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows narrow channels and small impact craters on the north flank of the Elysium volcano, Hecates Tholus.
Location near: 87.0°S, 108.1°W
Image width: ~1 km (~0.6 mi)
Illumination from: upper left
Season: Southern Summer
30 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows shallow tributary valleys in the Ismenius Lacus fretted terrain region of northern Arabia Terra. These valleys exhibit a variety of typical fretted terrain valley wall and floor textures, including a lineated, pitted material somewhat reminiscent of the surface of a brain. Origins for these features are still being debated within the Mars science community; there are no clear analogs to these landforms on Earth. This image is located near 39.9°N, 332.1°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (~108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30°S. The subtle, wavy pattern is a manifestation of fog.
Location near: 28°S, 286°W
Illumination from: upper left
Season: Southern Winter
17 September 2004
The upper crust of Mars consists of layered bedrock. The terrain located between large impact craters is layered. In some regions, some of these layers have been exposed by erosion. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows rounded and streamlined hills produced by wind erosion. In this case, the dominant, erosive winds blew from the upper right (northeast) toward lower left (southwest). The presence of these erosional forms, yardangs, indicates that the material being eroded contains some amount of sand-sized grains that are easily mobilized by wind. These particular yardangs are located in western Arabia Terra, northwest of the Sinus Meridiani region where the Mars Exploration Rover, Opportunity, has examined ancient sedimentary rocks. These landforms are located near 9.4°N, 6.5°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left.
24 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a thick, massive outcrop of light-toned rock exposed within eastern Candor Chasma, part of the vast Valles Marineris trough system. Dark, windblown sand has banked against the lower outcrop slopes. Outcrops such as this in the Valles Marineris chasms have been known since Mariner 9 images were obtained in 1972. However, the debate as to whether these represent sedimentary or igneous rocks has not been settled within the Mars science community. In either case, they have the physical properties of sedimentary rock (that is, they are formed of fine-grained materials), but some igneous rocks made up of volcanic ash may also exhibit these properties. This image is located near 7.8°S, 65.3°W, and covers an area approximately 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.
26 May 2004
The north polar cap of Mars is surrounded by fields of dark sand dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several dunes in the north polar region. The winds responsible for them blow from the lower left toward the upper right. The picture is located near 78.6°N, 243.9°W. Sunlight illuminates the scene from the lower left, and the picture covers an area about 3 km (1.9 mi) across.
28 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows banded terrain of the north polar region of Mars. The bands are exposures of layered material, possibly composed of dust and ice. The dark, rounded to elliptical mounds in this image might be the locations of ancient sand dunes that were completely buried in the north polar layered material. In more recent times, these mounds have been exhumed from within the layered material. Alternatively, the dark features are not ancient, exhumed dunes, but perhaps the remnants of a dark layer of material that once covered the entire area shown in the image. These features are located near 79.9°N, 31.4°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
14 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a heart-shaped hill surrounded by cracked terrain within a depression in far northwestern Arabia Terra, near the Cydonia region of Mars. Happy St. Valentine's Day from the MGS MOC team!
Location near: 39.1°N, 358.1°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: lower left
Season: Northern Spring
24 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows narrow channels and small impact craters on the north flank of the Elysium volcano, Hecates Tholus.
Location near: 34.0°N, 210.3°W
Image width: ~1 km (~0.6 mi)
Illumination from: upper left
Season: Southern Winter
9 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows detailed layered rock features, mantled by fine dust, in the Sulci Gordii ridged region east of Olympus Mons. The scene is located near 21.9°N, 124.3°W. The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the left.
30 January 2006
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical view of the martian northern plains during northern summer. In spring and summer, dust devils crisscross the plains, creating dark, filamentary streaks such as those shown here. MOC has rarely observed actual active dust devils on the northern plains, suggesting that these probably occur at a time of day that is different than the ~2 p.m. local time when MGS flies over these surfaces. As with high latitudes on Earth, daytime lasts longer in summer than at lower latitudes; thus, dust devils might occur earlier or later in the afternoon than is common in equatorial settings.
Location near: 69.5°N, 66.5°W
Image width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image illustrates very well the detailed, pitted nature of the north polar residual ice cap. As water ice sublimes away a little bit each summer, dark-floored pits have formed, trapping dust and other debris.
Location near: 85.1°N, 284.6°W
200 m scale bar = ~219 yards
Illumination from: lower left
Season: Northern Summer
This view of the "Columbia Hills" in Gusev Crater was made by draping an image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter (image E0300012 from that camera) over a digital elevation model that was derived from two Mars Orbiter Camera images (E0300012 and R0200357).
This unique view is helpful to the rover team members as they plan the journey of NASA's Mars Exploration Rover Spirit to the base of the Columbia Hills and beyond. Spirit successfully completed a three-month primary mission, and so far remains healthy in an extended mission of bonus exploration. As of sol 135 (on May 21, 2004), Spirit sits approximately 680 meters (0.4 miles) away from its first target at the western base of the hills, a spot informally called "West Spur." The team estimates that Spirit will reach West Spur by sol 146 (June 1, 2004). Spirit will most likely remain there for about a week to study the outcrops and rocks associated with this location.
When done there, Spirit will head approximately 620 meters (0.38 miles) to a higher-elevation location informally called "Lookout Point." Spirit might reach Lookout Point by around sol 165 (June 20, 2004). On the way, the rover will pass by and study ripple-shaped wind deposits that may reveal more information about wind processes on Mars.
Lookout Point will provide a great vantage point for scientists to remotely study the inner basin area of the Columbia Hills. This basin contains a broad range of interesting geological targets including the informally named "Home Plate" and other possible layered outcrops. These features suggest that the hills contain rock layers. Spirit might investigate the layers to determine whether they are water-deposited sedimentary rock.
Once at Lookout Point, Spirit will acquire 360-degree panoramic images of the entire area to help define the rover's next steps. Assuming the rover stays healthy, Spirit will eventually drive down into the basin to get an up-close look at interesting features there.
29 September 2004
The circular feature in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is the location of a buried impact crater in southern Noachis Terra near 55.4°S, 325.1°W. The image covers an area about 3 km (1.9 mi) across; thus the crater is roughly 2 km in diameter, or twice the size of the famous Meteor Crater in northern Arizona. A visitor to the Arizona Crater would be quite impressed by the height of its raised rims and the depth of and distance across its bowl, relative to a person. At the human scale It is challenging to imagine a crater twice that size that has been filled and buried by sediment and debris, yet the crater shown here is simply an example. On Mars, craters over 100 km in diameter have been buried, and some have been exhumed. This image is illuminated by sunlight from the upper left.
24 July 2004
The central peak of Oudemans Crater, located near 10.0°S, 92.1°W, contains light-toned, layered rock that has been uplifted and severely tilted. When seen from overhead, as in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, the dipping layered rocks form a banded pattern on the landscape. These rocks were once in the ground beneath the present floor of Oudemans Crater. The impact which produced the crater brought these rocks to the surface. They are light-toned and very similar to some of the varieties of sedimentary rock outcrops found in portions of the vast Valles Marineris trough system. Oudemans Crater sits on the edge of the Valles Marineris, near the intersection of the Labyrinthus Noctis and Ius Chasma. The image is illuminated by sunlight from the left/upper left. The 180 meter scale bar is equal to about 197 yards.
14 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer in November 2004, shows a group of three large afternoon dust devils occurring within several kilometers of each other in northwestern Amazonis. The image covers an area 3 km (1.9 mi) wide and was obtained with a spatial resolution of 12 meters (13 yards) per pixel. This scene is located near 36.2°N, 157.6°W. Sunlight illuminates the dust devils from the left.
14 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies with banked and somewhat sinuous channels and inner channels cut into the wall of a south middle-latitude crater near 46.6°S, 175.7°W. Banked channels are among the key evidence suggesting that some martian gullies involved flowing fluids with all of the physical properties of liquid water. The image covers an area about 2.3 km (1.4 mi) wide, and is illuminated by sunlight from the left.
21 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygon patterned ground in the south polar region near 82.0°S, 90.8°W. Polygons are fairly common at high latitudes in both martian hemispheres, but they do not occur everywhere. On Earth, features such as these would be good indicators of the presence and freeze-thaw cycles of ground ice. On Mars, the same might (emphasis on might) also be true. This image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left. Seasonal frost enhances the contrast in the scene; the darkest areas have advanced the farthest in the springtime defrosting process.
29 November 2004
Meteor impact craters are common the surfaces of most solid objects in the Solar System. They are least common on the volcanically-active moon of Jupiter, Io, and on Earth, where volcanism, tectonism, and erosion have all acted to erase the record of impact cratering. On Mars, erosion has also been vigorous enough to destroy craters. In other areas on Mars, craters have been filled and buried within the planet's bedrock. This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a relatively young impact crater on the floor of the outflow channel system of Mangala Valles. The impact ejecta blanket in this case is quite bouldery. Some windblown sediment has partially filled the crater. These features are located near 15.1°S, 149.3°W. The crater is just over 300 meters across, about one third the diameter of the famous Meteor Crater in Arizona. The 300 meter scale bar is about 328 yards long. Sunlight illuminates the scene from the upper left.
11 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dozens of light- and a few dark-toned sedimentary rock layers exposed by faulting and erosion in western Candor Chasma, part of the vast Valles Marineris trough system.
Location near: 6.5°S, 77.0°W
Image width: ~~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Southern Autumn
23 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows light-toned sedimentary rocks exposed by erosion in the Iani Chaos region of Mars.
Location near: 4.2°S, 18.7°W
Image width: ~1 km (~0.6 mi)
Illumination from: upper left
Season: Southern Winter
2 March 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical view of the vast martian northern plains. The dark, filamentary streaks were most likely formed by passing dust devils.
Location near: 53.3°N, 57.3°W
Image width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
16 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered rocks--in some areas eroded by wind to form yardangs--in eastern Candor Chasma, one of the troughs of the Valles Marineris system. The circular feature near the center of the image is a filled and partially-exhumed impact crater. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left. These features are located near 8.1°S, 66.9°W.
6 October 2004
This picture is a mosaic of three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images (E14-01679, M21-00388, M10-02183) and a lower resolution Mars Odyssey THEMIS VIS image (V09499005), showing details in an exhumed meteor impact crater in eastern Sinus Meridiani. Layered sedimentary rocks are seen within the crater and on the terrain outside the crater. This crater was once completely filled and buried within the martian bedrock. It was most likely encased in rock that is older than the strata being explored by the Mars Exploration Rover (MER-B), Opportunity, several hundred kilometers west of this area. Erosion has brought the old crater back to the surface of Mars. This landform is located near 0.7°N, 352.7°W. The 1 km scale bar is about 0.62 miles long. Sunlight illuminates the images from the left.
28 June 2004
Looking somewhat like caterpillars, this April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the rounded, wind-eroded sand dune features in a crater in the southern hemisphere near 61.7°S, 160.3°W. For such rounding to occur, the dune sand might need to be somewhat cemented. The picture covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
6 January 2004
The north polar cap of Mars is nearly surrounded by fields of dark, windblown sand dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 73.5°N, 75.0°W. The orientation of these dunes indicate that the dominant winds--particularly those that occur during storms--come from the upper left (northwest). The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the lower left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part of a large landslide complex off the north wall of Coprates Chasma in the Valles Marineris trough complex. The wall of Coprates Chasma occupies much of the upper and middle portions of the image; the landslide lobes are on the trough floor in the bottom half of the image. Large boulders the size of houses can be seen on these landslide surfaces. This image is locatednear 13.9°S, 56.7°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
16 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded layered rock outcrops in a crater north of Meridiani Planum near 2.7°N, 359.1°W. The dozens and dozens of sedimentary rock layers of repeated thickness and similar physical properties at this location suggest that they may have been deposited in a lacustrine (lake) setting. The crater in which these layers occur may once have been completely filled and buried, as is the case for many craters in the Sinus Meridiani region. This image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left.
6 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an outcrop of light-toned layered rock and a plethora of dark streaks on the floor of a crater in southern Noachis Terra. The streaks were created by dozens of dust devils which disrupted and perhaps removed some of the thin layer of dust that coats the surface. This view is located near 55.5°S, 333.4°W. The scene is illuminated by sunlight from the lower right. The 500 meter scale bar is approximately 547 yards long.
10 June 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in March 2004, shows Kunowsky Crater ringed by seasonal frost. Kunowsky is about 67 km (~42 mi) in diameter. Wavy clouds form to the east (right) of the crater in early spring as winds circulate from west to east. The crater is located at 57.1°N, 9.7°W. The picture is illuminated by sunlight from the lower left.
24 November 2004
Ancient valleys that may once have been the conduits through which water flowed are common on the surface of Mars. They are also found--filled and buried--in the subsurface, preserved in the rock record. In addition, erosion may take what was once the floor of a valley and leave it as a high-standing, flat-topped ridge. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a valley in eastern Arabia Terra that, in just one picture, exhibits both negative and positive relief forms. In negative relief, the valley is just that--a valley. In positive relief, instead of a valley, the former floor is now the top of a broad ridge. This MOC image is particularly instructive, because the transition from negative to positive (then back to negative and then again to positive) relief is captured in one small area. These landforms are located near 32.5°N, 314.1°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
30 May 2004
Seasonal frost can enhance the view from orbit of polar polygonal patterns on the surface of Mars. Sometimes these patterns look something like a city map, or the view from above a city lit-up at night. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the south polar region near 80.7°S, 70.6°W. Polar polygons on Mars are generally believed, though not proven, to be the result of freeze/thaw cycles of ice occurring within the upper few meters (several yards) of the martian subsurface. The image shown here covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
Researchers' goal in taking this image was to look for boulders in the large ripples formed by an ancient catastrophic flood in Mars' Athabasca Vallis. The Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft captured this image on Dec. 25, 2003, with use of an enhanced-resolution technique called compensated pitch and roll targeted observation.
The flood-deposited megaripples had been seen in earlier, lower-resolution images from the same camera. They are the only good examples known of ripples formed in a giant catastrophic flood anywhere on Mars. Their presence indicates that large amounts of water poured rapidly through this area, based on resemblance to similar megaripples in catastrophic flood sites on Earth. The ripples in Athabasca Vallis were buried for some period and later exhumed. Strange, round features on top of some of the ripples and the adjacent plains are products of erosion and removal of the overlying layer. Finding boulders in the ripples would help constrain estimates of the power of the floods. However, the image does not show boulders in the ripples, implying either that the rocks that make up these features are smaller than about 1 to 2 meters (3 to 7 feet) in diameter or that the ripple sediments have not been completely exhumed.
The image covers an area 3 kilometers (2 miles) wide, near 9.5 degrees north latitude and 203.7 degrees west longitude. Pixel size is about 1.5 meters (5 feet) by one-half meter (1.6 feet). North is up and sunlight illuminates the scene from the lower left.
Mars Global Surveyor is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Science Mission Directorate, Washington.
30 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows alternating light- and dark-toned bands--layers of sedimentary rock exposed by erosion in Becquerel Crater. Becquerel is located in western Arabia Terra near 4.1°N, 111.5°W, and might have once been the site of a lake. A few straight, narrow fault lines can be seen in the image; they cut the rock in trends that run from upper right toward lower left (northeast-southwest). This picture covers an area about 1.5 km (0.9 mi) wide and is illuminated by sunlight from the left.
17 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered, sedimentary rock outcrops in southwestern Melas Chasma, one of the troughs of the vast Valles Marineris system. Sunlight illuminates this scene from the upper left; it is located near 9.8°S, 76.0°W, and covers an area about 3 km (1.9 mi) wide.
15 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a strange ridged pattern developed in an eroding layer of material on the floor of a Labyrinthus Noctis depression in the Valles Marineris system. The ridges bear some resemblance to ripple-like dunes seen elsewhere on Mars, but they are linked to the erosion of a specific layer of material--i.e., something in the rock record of Mars. Similar ridged textures are found in eroded dark-toned mantling layers in regions as far away as northern Sinus Meridiani and Mawrth Vallis. The explanation for these landforms is as elusive as this image is evocative. The image is located near 8.2°S, 93.6°W, and covers an area 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
11 December 2004
Today's Mars Picture of the Day features two images. The top picture is a mosaic of Viking orbiter images acquired in the late 1970s. The lower image is a high resolution picture from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). The Viking mosaic shows Ceraunius Tholus, a volcano in the Tharsis region that was first viewed in images obtained by Mariner 9 in 1972. Several channels run down the slope of the Ceraunius Tholus volcano. The deepest of those channels ends in an elliptical crater. The elliptical crater was formed by a very oblique meteor impact. Where the channel meets the floor of the elliptical crater, there is a small mound of material. Presumably, this material was deposited in the elliptical crater after running down through the channel on the volcano's northwest flank.
Near the top/center of the mound in the elliptical crater is a small, circular depression. Some have speculated for years that this depression is related to volcanism, others thought that it may be an impact crater. The MGS MOC image (lower of the two images) shows that crater. It is not the source of lava flows or any other volcanic features. Most likely, it is an old impact crater. This feature is located near 25.2°N, 97.7°W. The MOC image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
17 June 2004
This April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fantastic outcrop of alternating light and dark layers in the wall of a crater that impacted into the floor of one of the eastern Kasei Valles flood channels. The history recorded in these layers, while unknown, might include the history of ancient floods in the Kasei Valles system. This crater wall is located near 31.1°N, 54.1°W. The 500 meter scale bar is about 547 yards long. Sunlight illuminates the scene from the upper right.
9 October 2004
Schiaparelli Basin is a large, 470 kilometer (~292 miles) impact crater located east of Sinus Meridiani. The basin might once have been the site of a large lake--that is, if the sedimentary rocks exposed on its northwestern floor were deposited in water. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.5 meter per pixel (5 ft per pixel) view of some of the light-toned, finely-bedded sedimentary rocks in northwestern Schiaparelli. The image is located near 1.0°S, 346.0°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
13 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows fine details among mid-latitude gullies formed on the walls of a large pit within a filled meteor impact crater in the Noachis Terra region of Mars. Like the gullies originally described in June 2000, these may have formed by the seepage of groundwater. Other scientists have speculated that, elsewhere on Mars, similar gullies might form by melting of ice or snow, by liquid or gaseous carbon dioxide, or dry mass movement (landsliding) processes. The many fine tributaries in the Noachis pit crater area shown here lend support to the hypothesis that a liquid with the physical properties of water was involved. This image is located near 47.8°S, 354.9°W, and covers an area approximately 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the upper left.
28 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an eroded, rounded hill in the Deuteronilus Colles region of Mars, near 40.3°N, 338.8°W. The plains surrounding the hill have been pitted and modified by erosion. Similar pitting is common throughout the middle latitude regions of Mars. Some Mars science investigators have proposed that the pitted materials were ice-rich, and that sublimation of ice has created these textures. However, no similar landforms are found on Earth, thus there is no clear analog that would help scientists better understand the origin of these features. The picture covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left/lower left.
NASA's Mars Exploration Rover Opportunity landed on the red planet a year ago. This enhanced-resolution image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter is the only picture obtained thus far (by Jan. 24, 2005) that shows the tracks made by Opportunity.
The image was acquired on April 26, 2004, during Opportunity's 91st martian day, or sol. That was the first day of Opportunity's extended mission, and the rover had recently completed exploration of small "Fram Crater" on the route from its landing site toward "Endurance Crater," where it would eventually spend six months. The rover itself can be seen in this image -- an amazing accomplishment, considering that the orbiter was nearly 400 kilometers (nearly 250 miles) away at the time! Also visible and labeled on this image are the spacecraft's lander, backshell, parachute and heat shield, plus effects of its landing rockets.
The camera captured this image with use of a technique called compensated pitch and roll targeted observation. In this method, the entire spacecraft rolls as it passes over the target area so the camera can scan in a way that sees details at three times higher resolution than the camera's normal high-resolution capability.
The tracks made by Opportunity on the sandy surface of Meridiani Planum are not quite as visible from orbit as are the tracks made in Gusev Crater by the other Mars Exploration Rover, Spirit. A dustier surface at the Spirit site increases contrast between the tracks and the surrounding surfaces. Indeed, some parts of the track made by Opportunity are not visible in this image. Sunlight illuminates the scene from the left. North is toward the top of the image. The 100-meter scale bar is 109 yards long.
16 November 2004
This 1.6 meters (~5 feet) per pixel Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical north polar scarp and associated dark, windblown sand dunes. Layers of material -- possibly dust and ice -- are exposed by the scarp. The small white patches in the image are remnants of seasonal frost. When this north polar image was acquired in late September 2004, most of the polar frost had sublimed away. This image is located near 85.1°N, 210.8°W. The scene covers an area approximately 3 km (1.9 mi) across, and is illuminated by sunlight from the lower left.
31 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sedimentary rock outcrops within a crater in western Arabia Terra near 8.8°N, 1.3°W. These are eroded from the same rocks as seen in an earlier MOC Picture of the Day from 1 December 2003. The repeated nature of these layers indicate episodic changes took place in the sedimentary depositional environment. The sediments may have been deposited in an intracrater lake. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left/upper left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust devil in far western Syria Planum. The dust devil is located near the left-center of the image. It is casting a shadow toward the lower right (southeast).
Location near: 14.5°S, 109.6°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
16 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows two large and many small mesas composed of frozen carbon dioxide on the south polar cap of Mars. MGS has observed the south polar cap through three whole summers, and MOC images have shown that the scarps on these mesas retreat an average of 3 meters--some retreat faster, some a bit slower--per martian summer. The south polar cap is the most rapidly-changing landscape on Mars. These mesas are located near 86.5°S, 358.5°W. The image covers an area approximately 2 km (1.2 mi) across and is illuminated by sunlight from the upper left.
27 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a large field of small craters clustered together in northeastern Arabia Terra. Crater clusters usually result from the secondary impact of debris thrown from a much larger impact or from the break-up and impact of fragments of a large meteor. Each crater has subsequently been partially filled by material that erodes to form a rugged crater floor surface, and the general appearance of each crater has been somewhat eroded and modified, as well. The image is located near 34.7°N, 314.7°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
11 September 2004
An impact crater in western Arabia Terra at 8°N, 7°W, exhibits some of the most fantastic sedimentary rock outcrops on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The crater interior has hundreds of sedimentary rock layers, each of a similar thickness and similar physical properties. The similarities between beds and their repeated nature have been used to suggest that the crater was once the site of a lake. Today, the sedimentary rocks are eroded and dark, windblown sand covers some of them. Faults cut and offset beds in some places. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.
26 September 2004
This blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the frost-covered rims of Lomonosov Crater in late martian spring. At the north (top) end of the image, low, ground-hugging fog can be seen in association with the retreating seasonal polar cap. Lomonosov Crater is about 150 km (93 mi) in diameter and located at 65°N, 9°W. The image is illuminated by sunlight from the lower left.
29 July 2004
Hundreds of large ripples or small dunes cover the landscape in the Terra Tyrrhena region of Mars in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. The winds responsible for these dunes blew from the north-northwest (top/upper left). This scene is located near 8.8°S, 252.8°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the terrain from the left.
This digital elevation map shows the topography of the "Columbia Hills," just in front of the Mars Exploration Rover Spirit. Rover planners are currently plotting the safest route for Spirit to climb to the front hill, called "West Spur." The direct path from the bottom crosshatch to the top crosshatch may be too steep. Data from the Mars Orbital Camera on the orbiting Mars Global Surveyor were used to create this 3-D map.
5 March 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rocks in southwestern Melas Chasma.
Location near: 10.0°S, 75.9°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Autumn
31 July 2004
The sedimentary rock outcrops explored this year by the Mars Exploration Rover, Opportunity, in Meridiani Planum are just the "tip of the iceberg." Northern Sinus Meridiani exhibits vast outcrops of sedimentary rock of widely varied erosional characteristics and physical properties. Investigation of these rocks from orbit using the high resolution capabilities of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has been underway for nearly seven years. This MGS MOC image shows an example, complete with small buttes formed of eroded sedimentary rock, in northern Sinus Meridiani. The image is located near 1.2°N, 358.9°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the terrain from the left.
2 November 2004
When it comes to planetary surfaces, the more craters there are, the older the terrain is believed to be. However, because the martian surface has experienced considerable episodes of erosion as well as burial of craters, a surface covered with many small craters on Mars is often one that is more resistant to erosion, not necessarily one that is older than a less-cratered surface. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of an extremely cratered surface. This can be contrasted with nearly any of the exposures of martian sedimentary rock, which are very old but do not retain as many craters because they are more easily eroded. Hundreds of examples of martian sedimentary rock outcrops are listed in the MOC Captioned Release, Sedimentary Rocks gallery. This image is located near 33.6°S, 204.7°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
06 August 2004
The springtime retreat of the north polar seasonal frost cap is progressing on schedule. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the state of defrosting north polar sand dunes just three days ago on 3 August 2004. Dark areas on the dunes are patches of bare sand; bright areas are remnants of frost deposited during the previous winter. Summer will arrive on 20 September 2004. These dunes are located near 76.3°N, 263.5°W. Their steepest slopes, known as the slip face of each dune, point toward the northeast (upper right), indicating wind transport of sand from the southwest (lower left). The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
15 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the results of a small landslide off of a hillslope in the Aureum Chaos region of Mars. Mass movement occurred from right (the slope) to left (the lobate feature pointed left). Small dark dots in the landslide area are large boulders. This feature is located near 2.6°S, 24.5°W. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/upper left.
21 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the results of a process that is underway in the Memnonia uplands near 12.9°S, 152.7°W, to strip away one layer of material and reveal a formerly-buried landscape from beneath. All of the area shown here was once covered by a material that has been eroded by wind to form the sharp-crested, nearly-parallel ridges that run diagonally from the upper left toward lower right in this image. These ridges are a classic wind erosion form, known as a yardang. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left/upper left.
1 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows landforms in southeastern Ius Chasma, part of the Valles Marineris trough system. Near the top of the image are light-toned rock outcrops; at the bottom center is a small butte--the remnant of some formerly more extensive rock unit. The lower two thirds of the picture is dominated by dark, windblown sand dunes. The image is located near 8.7°S, 79.2°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the terrain from the lower left.
5 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows windblown sand dunes in Herschel Basin, a large impact crater in the Terra Cimmeria region of Mars. The dunes of Herschel have grooved surfaces, indicating that their sands are somewhat cemented. Wind has blasted and eroded the cemented sand to form the grooves. This image was acquired in August 2004 and is located near 15.6°S, 228.4°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
18 September 2004
Apollinaris Patera is an ancient volcano located northwest of Gusev Crater, the landing site of the Mars Exploration Rover, Spirit. Apollinaris Patera, being rather old, is covered with craters, mantles of dust, and a wind-scoured covering of indurated, fine material. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small portion of the Apollinaris Patera volcano, revealing the exhumation of older surfaces from beneath a relatively thin, wind-scoured material. This view is located on the upper south slope of the volcano, near 9.5°S, 186.4°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
9 June 2004
Martian dust devils sometimes disrupt thin coatings of surface dust to create dark streak patterns on the surface. However, not all dust devils make streaks, and not all dust devil streaks are dark. In Syria Planum, the streaks are lighter than the surrounding plains. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example from Syria near 8.8°S, 103.6°W. The thin coating of surface dust in this region is darker than the substrate beneath it. This is fairly unusual for Mars, because most dust is bright. This image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.
16 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered outcrops of sedimentary rock exposed at the top of a small mesa in northern west Candor Chasma of the Valles Marineris trough system. Large, dark, windblown ripples cover the plains surrounding the mesa. These features are located near 5.4°S, 74.6°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
10 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows ripples on the surface of a dune in a crater west of Sinus Meridiani near 2.5°N, 9.3°W. Most martian dune surfaces do not show ripples at the scale of MOC images---a higher resolution (better than 15 cm/pixel) view would be needed. These ripples are probably not typical sand ripples; they may be coarser-grained granule ripples (usually made up, in part, of grains 1-4 millimeters in size). The light-toned features in the image are wind-eroded outcrops of sedimentary rock. The image covers an area about 1.5 km (~0.9 mi) wide. Sunlight illuminates the scene from the upper left.
21 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows low albedo (dark), windblown sand dunes on the floor of Bunge Crater, located near 33.8°S, 48.9°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
5 July 2004
Burial and exhumation is a theme that repeats itself, all over the surface of Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several north mid-latitude meteor impact craters with bouldery ejecta deposits. Each of the craters was once buried and later exhumed. Mesas on the floors of these craters are remnants of the materials that once filled and covered them. The craters are located near 39.7°N, 206.0°W. The image covers an area about 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
20 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer in December 2004, shows dark, windblown sand dunes in the north polar region of Mars. A vast sea of sand dunes nearly surrounds the north polar cap. These landforms are located near 80.3°N, 144.1°W. Light-toned features in the image are exposures of the substrate that underlies the dune field. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
28 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a gully formed in the wall of a north middle-latitude crater. Similar gullies are common at the middle and polar latitudes of Mars, and might have formed by the action of liquid water. Others have argued for carbon dioxide or dry mass movement for the genesis of such landforms. This particular image was acquired during northern autumn, when the sky over the terrain of the martian northern mid-latitudes is typically hazy.
Location near: 50.0°N, 356.9°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
31 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in the north polar region of Mars. They are streaming away (toward the left) from a low escarpment at the edge of an outlier of polar water ice (the bright area on the right). The picture covers an area about 3 km (1.9 mi) wide and is located near 80.7°N, 80.2°W. Sunlight illuminates the scene from the lower left.
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows a high resolution view of portions of the lobes of several landslide deposits in Ganges Chasma. Dark material near the bottom (south) end of the image is windblown sand.
Location near: 8.2°S, 44.3°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
31 May 2004
Springtime for the martian northern hemisphere brings defrosting spots and patterns to the north polar dune fields. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 76.7°N, 250.4°W. In summer, these dunes would be darker than their surroundings. However, while they are still covered by frost, they are not any darker than the substrate across which the sand is slowly traveling. Dune movement in this case is dominated by winds that blow from the southwest (lower left) toward the northeast (upper right). The picure covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
18 November 2004
Middle- and polar-latitude martian gullies remain as much a mystery today as they were when first announced in June 2000. Some have argued that they form by running water, others argue they required carbon dioxide in liquid or gas form, still others have proposed that these features form "dry" by simple landsliding processes (although landslides elsewhere on Mars do not form features that look like the martian gullies). They occur almost exclusively at latitudes higher than 30° in both hemispheres, although they are more common in the southern hemisphere. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a very small gully example in a crater that is only about 1 km across -- roughly the size of the famous Meteor Crater in northern Arizona. The debris transported through the gullies was deposited on top of light-toned, windblown ripples on the floor of the crater, indicating that the ripples are older. This crater is located near 37.9°S, 169.3°W. The 150 meter scale bar is about 490 feet long. Sunlight illuminates the scene from the upper left.
16 October 2004
Aram Chaos is the name of an approximately 275 km (171 mi) diameter impact crater near Ares Vallis, roughly half way between the Mars Exploration Rover, Opportunity, site in Meridiani Planum and the easternmost troughs of the Valles Marineris. The Aram Chaos crater is partially filled with a thick accumulation of layered rock. Erosion has exposed light- and dark-toned rock materials in the basin. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small area exhibiting some of the rock outcrops in Aram Chaos. The light-toned rocks may be sedimentary in origin. This image is located near 4.0°N, 20.6°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
7 June 2004
Presently, it is autumn in the southern hemisphere of Mars. Sand dunes at high and middle latitudes are becoming cold and frosted. This frost, probably water ice, is persistent enough that it is still present around 2 p.m. in the afternoon, when Mars Global Surveyor (MGS) flies over these dune fields. This MGS Mars Orbiter Camera (MOC) image shows an intracrater dune field at 59.4°S, 158.9°W, as it appeared last week on 3 June 2004. In summer, these dunes would be very dark relative to the substrate on which they occur. In autumn, as shown here, they begin to accumulate frost that will last through the coming winter. Southern hemisphere winter will arrive around 20 September 2004. The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
23 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of southern middle-latitude gullies cut into the wall of an impact crater located near 32.1°S, 12.9°W. These gullies might indicate that groundwater seeped to the surface and ran down these slopes. Others have suggested that similar gullies on Mars might form by other processes, including melting of ground ice or snow, but this image does not provide any clues that would suggest either of these alternatives are better than the groundwater interpretation. The 300 meter scale bar is about 984 feet long. Sunlight illuminates the scene from the upper left.
2 July 2004
Beneath the ice caps of both martian poles lies extensive deposits of layered material. Whether the material includes ice is unknown. In the north polar region, some of the layers contain dark sand, others may consist of dust cemented by ice. The south polar layers are a little bit more challenging to understand. In most places, they have been covered by thin mantles of debris that mask the true nature of the layered material. This is the case, even in the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shown here. South polar layers were eroded to provide this spectacular view, but later the materials were almost uniformly covered with a material that, when the image is viewed at full resolution (click on image, above), has become cracked. This picture is located near 82.0°S, 72.4°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
Wheel tracks left by the NASA rover Spirit's 3-kilometer (2-mile) trek from its landing site to the "Columbia Hills" are visible in this orbital view from the Mars Orbiter Camera on NASA's Mars Global Surveyor. Spirit's rover track shows up nicely from orbit because the surfaces disrupted and churned by the wheels are darker than the surrounding, dust-coated plain. North is up.
The largest crater in the view, dubbed "Bonneville Crater," is about 210 meters (230 yards) in diameter. The picture is a composite of Mars Orbiter Camera image R15-02643, taken on March 30, 2004, when Spirit was near the south rim of Bonneville Crater, and image R20-01024, taken Aug. 18, 2004, when Spirit was climbing the hills' western spur, seen in the picture's bottom right corner.
New Dark Streak Near Spirit
In figure 1, frames taken from orbit 20 weeks apart (top pair) and by the NASA rover Spirit at ground level (bottom) show the formation of a new dark streak on the ground in the area where Spirit was driving inside Mars' Gusev Crater in April 2004. The new dark streak and other dark streaks in the area are believed to result from dust devils removing brighter dust from the surface.
The upper frames were taken by the Mars Orbiter Camera aboard NASA's Mars Global Surveyor. They are from the same pair of images combined to create the orbital view of the NASA rover Spirit's trail from the rover's landing site to the "Columbia Hills." The orbiter took the upper-left picture on March 30, 2004 (Spirit's 85th martian day, or sol). It took the upper-right picture on Aug. 18, 2004 (Spirit's sol 223). A dark streak occurs in the larger crater in the lower right quarter of the August image. This streak was not present when the March image was obtained. Inspection of the lower image, which was taken by Spirit's navigation camera when the rover was at the rim of this crater on sol 106 (April 20, 2004), reveals that the streak was present by then. Thus, the dust devil must have occurred some time between March 30 and April 20. The dust devil was not observed by the rover.
In addition to the formation of this dark streak, another change seems to have occurred at the landing site. The rover track between the lander and Bonneville Crater seems to have faded between March 30 and Aug. 18. This could be an artifact of the different sunlight illumination conditions between the two images, or it may indicate that fine dust settled on the older portions of the track, obscuring it. The Mars Orbiter Camera team plans to re-visit the Spirit lander site from time to time to see what other changes may occur.
Orbital View of Spirit's Neighborhood
The three-frame set in figure 2 is a segmented version of the orbital view of the NASA rover Spirit's trail from the rover's landing site to the "Columbia Hills." The images were taken by the Mars Orbiter Camera on NASA's Mars Global Surveyor. North is up.
The location of Spirit's lander, parachute, and backshell are indicated in frame A, and the rover track down toward the Columbia Hills can be traced through A, B, and C. In frame A, "Bonneville Crater" is the largest crater. Spirit drove up to Bonneville's rim and looked inside before driving away toward the southeast. The base of the Columbia Hills is seen in the lower right quarter of frame C. In frame B, notice that the rover track followed along the edge of a lighter-toned streak and wider dark streak, believed to have been formed by a dust devil before Spirit landed. The proximity of the rover to this streak was not recognized in rover images.
23 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows fine details in the walls and floor of a meteor impact crater located immediately west of the Lycus Sulci ridged terrain, northwest of the volcano, Olympus Mons. The walls of the crater exhibit the finely-detailed layering of the local bedrock. This crater is centered near 31.4°N, 147.7°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
29 December 2004
Craters on the northern plains of Mars are not usually found at the surface. Typically, they are filled and buried just beneath it. The crater shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an example. The crater is located near 50.3°N, 46.7°W. Dark streaks crisscrossing the scene were formed by passing dust devils. The picture covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
27 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, windblown sand dunes on the floor of Herschel Crater. The surfaces of the dunes have grooves eroded into them. This indicates that the sand is not loose, like it is in typical sand dunes on Earth. Instead, the sand is cemented, and wind erosion has been slowly scouring the indurated sands away to create small-scale wind erosion features, known as yardangs. This picture covers an area about 3 km (1.9 mi) across, and is located near 15.6°S, 229.0°W. Sunlight illuminates the scene from the upper left.
30 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of an old impact crater that was filled, buried, and is now being exhumed from within sedimentary rock strata located in western Arabia Terra, the region immediately north of Meridiani Planum. The Mars Exploration Rover, Opportunity, has explored sedimentary rocks in the Meridiani region; the rocks of nearby western Arabia can only be explored (for the time being) from orbit. Wind has sculpted some of the layered rock into streamlined forms known as yardangs. The crater shown here, at one time, may have been the site of a small lake. The crater is located near 8.4°N, 5.7°W. The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
21 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rock outcrops in south-central Becquerel Crater in western Arabia Terra near 21.3°N, 8.4°W. The layered material may have been deposited in an intracrater lake, early in martian history. The material has subsequently been exposed and eroded by wind. Dark sand dunes have accumulated along the southern margin (bottom of image) of the outcrop exposure. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left/lower left.
14 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a leveed channel running down the middle of a lava flow in Daedalia Planum, the southern plains of the Tharsis volcanic region. Transport of fluid lava through a channel such as this helps insulate the molten rock, keeping it hot longer, and thus permits the flow to extend to greater distances than it otherwise might. This example is located near 23.6°S, 123.2°W, and covers an area approximately 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the upper left.
18 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows barchan and linear dunes that seem to have grown from the coalescence of barchans in a crater in the Noachis Terra region. The winds responsible for these dunes blow from the lower left (southwest). The image occurs near 46.0°S, 323.6°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
10 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in March 2004, shows gullies formed in the wall of a south middle-latitude crater wall near 39.7°S, 208.6°W. The banked, curved nature of the channels in each gully are among the key indicators that a fluid, such as liquid water, may have been required to form them. The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
12 December 2004
Burial and exhumation of impact craters, and their destruction by erosion, are common and repeated themes all over the surface of Mars. Many craters in western Arabia Terra exhibit light-toned, layered outcrops of ancient sedimentary rock. Like the sedimentary rocks explored further to the south in Meridiani Planum by the Opportunity Mars Exploration Rover (MER-B), these intracrater sedimentary rocks may have been deposited in water. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example of light-toned sedimentary rocks outcropping in a crater that is much farther north than most of the similar examples in western Arabia. This one is located near 36.6°N, 1.4°W, and shows several old impact craters in various states of erosion and exhumation from beneath and within the sedimentary rock materials. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
16 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the banded southeastern floor of the giant impact basin, Hellas. Hellas Planitia is a large and varied region. In southeastern Hellas, banded terrain is fairly common. The pattern probably results from erosion of layered sediment that was subsequently covered by a mantling material. This mantling material later was eroded and roughened the terrain somewhat. This image is located near 41.1°S, 275.6°W. The picture covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
18 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows groupings of large ripple-like windblown bedforms on the floor of a large crater (larger than the image shown here) in Sinus Sabaeus, south of Schiaparelli Basin. These ripple-like features are much larger than typical wind ripples on Earth, but smaller than typical sand dunes on either planet. Like most of the other ripple-like bedforms in Sinus Sabaeus, they are probably ancient and no longer mobile. Dark streaks on the substrate between the bedforms were formed by passing dust devils. This image is located near 13.0°S, 343.7°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.
5 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an exposure of layered material, probably sediment, on the floor of Shalbatana Vallis. Erosion has exhumed small impact craters and created round, layered buttes. This image is located near 3.2°N, 43.4°W, and covers an area approximately 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the lower left.
11 June 2004
These four Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images show north polar sand dunes as they appeared on four different days over the past ten weeks. In summer, the dunes would be darker than the substrate on which they occur. However, it is currently spring in the northern hemisphere, and the dunes are still covered with frost from the previous winter. The MGS MOC has been busy over the past several months, documenting the changes in frost patterns that occur on dunes and interdune substrates all over the north polar region. The site shown here was imaged on 30 March, 23 April, 16 May, and 9 June 2004. The bright frost that covers the dunes progressively changes from one image to the next, as dark spots develop and frost sublimes away. This defrosting dune monitor site is located near 80.0°N, 237.5°W. Each strip is about 1.1 km (0.7 mi) wide and illuminated by sunlight from the lower left.
29 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lava flows on the middle west flank of the large martian volcano, Ascraeus Mons. The flows ran downslope from the lower right (southeast) toward upper left (northwest). These flows are located near 11.9°N, 105.5°W. This December 2003 image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the lower left.
Wheel tracks left by NASA's Mars Exploration Rover Spirit, and even the rover itself, are visible in this image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter. North is up in this image. The tracks and rover are in the area south of a crater informally named "Bonneville," which is just southeast of the center of the image. The orbiter captured this image with use of an enhanced-resolution technique called compensated pitch and roll targeted observation. It took the picture on March 30, 2004, 85 martian days, or sols, after Spirit landed on Mars. The rover had driven from its landing site to the rim of Bonneville and was examining materials around the crater's rim.
In this portion of the plains inside the much larger Gusev Crater, Spirit created wheel tracks darker than the undisturbed surface, as seen in the rover's own images showing the tracks (for example, PIA05450). The contrast allows the tracks to show up in the image obtained from orbit. Also visible are Spirit's lander, backshell and parachute, and the scar where its heat shield hit the ground.
The full image covers an area 3 kilometers (2 miles) wide, at 14.8 degrees south latitude and 184.6 degrees west longitude. Pixel size is about 1.5 meters (5 feet) by one-half meter (1.6 feet). Sunlight illuminates the scene from the upper left.
Mars Global Surveyor is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Science Mission Directorate, Washington.
31 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows collapse pits on the northern flank of the giant Tharsis shield volcano, Ascraeus Mons. Details in rock and dust are seen when this image is examined at its full, 1.5 meters (5 ft) per pixel resolution. Large, dark boulders occur on the floors of some of the pits, for example. This scene is located near 13.1°N, 103.1°W. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
18 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows troughs and a pit, possibly formed by collapse, on the volcanic plains south of the large volcano, Ascraeus Mons. Wind-eroded debris mantles the scene and partly fills the depressions. The image is located near 4.5°N, 105.5°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
30 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of dunes in the martian north polar region is important because it shows one of the highest northern latitude views of streaks thought to be made by passing dust devils. The dark, thin, filamentary streaks on the dunes and on the adjacent plains were probably formed by dust devils. The dunes occur near 76.6°N, 62.7°W. Dust devil streaks are observed on Mars at very high latitudes, such as this, all the way down to the equator. They are also seen at all elevations, from the deepest parts of the Hellas Basin to the summit of Olympus Mons. This picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
5 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an impact crater, a little over 2 km (> 1.2 mi) in diameter, located in Noachis Terra near 50.4°S, 14.3°W. The crater's bouldery ejecta blanket has protected underlying material from being eroded away by wind, leaving the ejecta up on a low pedestal. This picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the upper left.
28 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a light-toned butte composed of layered, sedimentary rock in the Iani Chaos region of Mars. It is located near 1.6°S, 18.2°W. The picture covers an area about 3 km (1.9 mi) wide, and is illuminated by sunlight from the left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides a representative view of the vast martian northern plains in the Diacria region near 52.8°N, 184.7°W. This is what the plains looked like in late northern spring in August 2004, after the seasonal winter frost had sublimed away and dust devils began to leave dark streaks on the surface. Many of the dark dust devil streaks in this image are concentrated near a low mound -- the location of a shallowly-filled and buried impact crater. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
17 January 2004
The top half of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows wind-eroded remnants of sedimentary rock outcrops in Ganges Chasma, one of the troughs of the Valles Marineris system. The lower half shows a thick accumulation of dark, windblown sand. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left. These features are located near 7.6°S, 49.4°W.
7 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered rock outcrops in a pitted and eroded region just northeast of Hellas Planitia. The light-toned materials are most likely sedimentary rocks deposited early in martian history (but long after the Hellas Basin formed by a giant asteroid or comet impact). The scene also includes a plethora of large dark-toned, windblown ripples. The image is located near 27.2°S, 280.7°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
9 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a variety of dark sand dune patterns and shapes in the north polar region of Mars. Small, aligned dunes in some cases have merged to form elongated dunes. These features are located near 76.4°N, 272.9°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
29 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of small yardangs -- wind eroded hills -- on the plains immediately west of Meridiani Planum. These yardangs are the remains of layered, sedimentary rock that once covered this area. The few craters visible in this 3 km (1.9 mi) -wide scene are all exhumed from beneath the rocks that comprise the yardang hills. The image is located near 0.4°S, 7.2°W. Sunlight illuminates the picture from the lower left.
20 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows troughs and a pit chain (on the floor of the deeper trough) located immediately northeast of the giant Tharsis volcano, Arsia Mons. Lava flows have been cut by these troughs, which formed along fault lines when the crust expanded and rock between the fault lines was raised up or dropped down relative to its original position. Troughs formed in this way are known as graben. This image is located near 7.1°S, 115.0°W. The scene covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
15 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several meteor impact craters on Solis Planum. The second-largest crater in this scene is relatively young and fresh, exhibiting arrayed ejecta pattern and numerous boulders near its raised rim. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left. The craters are located near 19.8°S, 85.5°W.
1 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, windblown dunes on the floor of Bamburg Crater, located in the Cydonia region near 39.7°N, 3.2°W. The winds responsible for these dunes flow generally from north to south. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the lower left.
28 August 2004
Light-toned, layered, sedimentary rock outcrops are common within the vast martian Valles Marineris trough system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a recent example from southern Melas Chasma at 1.5 m/pixel (5 ft/pixel) resolution. The image is located near 11.3°S, 73.9°W, and covers an area about 1.8 km (1.1 mi) across. Sunlight illuminates the scene from the upper left.
30 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image was acquired using the cPROTO technique described on 27 September 2004 in "cPROTO Views of Spirit's Rover Tracks and Athabasca Vallis Flood Features." In other words, the picture was obtained by MOC with a resolution that is better than 1 meter per pixel (better than 3 feet per pixel). On the left is a view of the entire cPROTO image; on the right is a magnified view of the features seen in the white box on the left. The 200 meter scale bar is about 219 yards long. This cPROTO image, obtained in August 2004, shows layered sedimentary rocks exposed in eastern Candor Chasma, part of the vast Valles Marineris trough system. On the steep slope in the lower half of the image (left), the rocks have been breaking down into fine-grained material that slides down the slope to create fan-shaped talus accumulations. In some cases, the movement of this dry debris has cut narrow, straight chutes into the slope. The sub-meter resolution of the cPROTO image reveals that there are no boulders in the talus, attesting to the extremely fine-grained and easily broken-up nature of these sedimentary rocks. The image is located near 7.3°S, 69.0°W. Sunlight illuminates the scene from the upper left.
12 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the remains of two impact craters that were filled, buried, and then exhumed from within layered sedimentary rock in the martian crater, Gale. Wind erosion has sculpted tapered yardang ridges in the uppermost rock layers exposed at this location.
This is the 1000th captioned image release from the MGS MOC team. The first release occurred in July 1997, when the spacecraft was still speeding toward the red planet. Many people have asked "why are the releases numbered starting with 'MOC2'?" The MGS MOC is the second MOC, so it is designated "MOC2." The first MOC was flown on the Mars Observer spacecraft, which was lost just before arrival at Mars in August 1993. The MOC science investigation was originally selected by NASA in 1986. The MGS MOC effort is currently in its third extended mission, and is funded through at least October 2006.
Location near: 5.0°S, 222.8°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
Voir l'image PIA07353: MOC 1000th Release! sur le site de la NASA.
3 March 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows boulders on the floor of a wide trough in Memnonia Fossae.
Location near: 18.8°S, 150.3°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
27 November 2004
Sinus Meridiani is the site of the largest outcropping of light-toned, layered sedimentary rocks on Mars. Last January, the Mars Exploration Rover (MER-B), Opportunity, landed in a portion of central Sinus Meridiani and has since that time been exploring the local outcrops of light-toned, sedimentary rock. Where Opportunity landed, most of the sedimentary rocks are covered by a regolith of windblown sand and granules. At the rover site, rock outcrops are found mostly in crater walls. Further to the north, the outcrops are not covered with sediment. Vast plains of exposed sedimentary rock, covering an area several times larger than all the sedimentary rock exposures of northern Arizona, New Mexico, and eastern Utah, combined, are found in northern and eastern Sinus Meridiani. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the northern Sinus Meridiani sedimentary rock outcrops. It also shows the locations of several meteor impact craters that have been degraded as the sedimentary rocks have been eroded away. The large, dark, circular area near the top of the picture may mark the location of a crater that is still mostly filled and buried beneath dark, windblown debris. The sedimentary rocks of northern Sinus Meridiani have been known to occur there for at least the past seven years. They were initially described in a paper in Science describing MOC results about sedimentary rocks on Mars, published in December 2000 (see "Sedimentary rocks of early Mars"). This image is located near 2.3°N, 2.0°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
25 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows old, light-toned, large ripples on a smoothly mantled surface in the Sinus Sabaeus region, south of Schiaparelli Basin. This image is located near 6.4°S, 341.8°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
13 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygons formed in ice-rich material in the north polar region of Mars. The bright surfaces in this image are covered by a thin water ice frost.
Location near: 79.8°N, 344.8°W
Image width: ~1.5 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
28 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows landforms, including large, windblown ripples, on the floor of the ancient, giant Argyre impact basin.
Location near: 48.0°S, 42.2°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Winter
12 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, sedimentary rock outcrops in the Aureum Chaos region of Mars. On the brightest and steepest slope in this scene, dry talus shed from the outcrop has formed a series of dark fans along its base. These outcrops are located near 3.4°S, 27.5°W. The image covers an area approximately 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.
8 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows windblown sand dunes in Lohse Crater in Noachis Terra near 43.8°S, 16.8°W. The winds responsible for these dunes blew largely from the lower left (southwest) toward the upper right (northeast). The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the upper left.
The large circular feature in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is the expression of a formerly filled and buried meteor crater, locked within sedimentary materials eroded by wind in the Memnonia Sulci region of Mars. The ridges and troughs in the image attest to the power of wind erosion to form yardangs.
Location near: 1.6°N, 173.9°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Northern Summer
10 July 2004
Light-toned, layered rock outcrops occur in small patches as well as large regional exposures within the chasms of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small area of layered outcrop in the floor of Coprates Chasma. The image is located near 14.0°S, 64.0°W, and covers an area about 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the left/upper left.
24 August 2004
The upper left (northwest) corner of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater within which are several layers of eroded material. This crater, and probably all of its degraded neighbors, was once filled and buried, and was later exhumed. The burial and exhumation theme is one that repeats all over the surface of Mars, as ancient rocks are eroded to expose previously filled and buried craters, valleys, and landscapes. This particular image is located near the northwest rim of Kaiser Crater, in Noachis Terra, near 45.2°S, 342.7°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
16 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows landforms on the floor of Antoniadi Crater. The circular features were once meteor impact craters that have been almost completely eroded away.
Location near: 21.6°N, 297.4°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Northern Summer
19 October 2004
The fretted terrains of Mars were described briefly earlier this month in "Craters in Fretted Terrain." Today's Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Picture of the Day shows another example of a fretted terrain valley floor with its characteristic lineated and finely-pitted texture. Four circular features near the center/left center of the image are suspected to be the locations of meteor impact craters that have been largely eroded away. Mars is a complex world upon which have acted processes of erosion that are not fully understood. This image is located near 40.4°N, 336.2°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, windblown sand dunes in the north polar region of Mars. The scene, obtained in December 2004, is located near 85.2°N, 169.1°W. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper right.
26 December 2004
A little over 11 months ago, the Mars Exploration Rover, Opportunity, landed on Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small portion of Meridiani Planum -- too far from the rover for it to investigate--that has been peppered with small impact craters. The majority of craters, particularly those in the lower half of the image, are secondary impacts caused by the landing of rock and debris ejected from a much larger impact crater, located elsewhere in the region. The large, nearly circular depression at the top center of the image is the site of a much older crater that was filled and almost completely buried beneath the plains. As result of the rover's work in Meridiani Planum, it is now known that the bright rims and walls of the craters are, at least in part, exposures of sedimentary rock. The dark material covering the plains, according to rover results, is mostly very fine sand plus millimeter-sized granules. This picture covers an area about 3 km (1.9 mi) across, and is located near 2.5°S, 3.3°W. Sunlight illuminates the scene from the left.
14 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a small, 280-meter (~919 feet)-diameter meteor impact crater in south polar layered terrain. The ejecta from the crater today stands somewhat higher than the surrounding terrain, suggesting that, at the time the impact occurred, the surface was several meters higher than it is today. A layer of material, several meters thick, has been stripped away since the time the crater formed. The image is located near 86.3°S, 113.0°W, and covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
12 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows small, dark, north polar sand dunes and attendant wind streaks located near 76.7°N, 317.6°W. The dominant winds responsible for these features blow from the southwest (lower left). The image covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.
8 December 2004
Yardangs are ridges formed by wind erosion. Most commonly, they will form in sedimentary rocks or volcanic ash deposits containing some amount of sand-sized grains (particles of 0.0625 to 2.0 millimeters size, like the grains in common table salt). This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of yardangs in the Memnonia Sulci region. The scene is located near 9.3°S, 172.4°W, and covers an area about 3 km (1.9 mi) wide. The ridges are illuminated by sunlight from the upper left.
19 July 2004
This full-resolution (1.5 meters, 5 feet, per pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows mesa tops and depressions formed in layered carbon dioxide ice in the south polar residual cap. The image is located near 87.0°S, 341.9°W, and covers an area about 1.5 km (0.9 mi) wide. Sunlight illuminates the scene from the upper left.
12 July 2004
Wind erosion has created yardang ridges and revealed the location of a formerly-buried meteor crater (see lower left corner) in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. This scene is located in the Apollinaris Sulci region near 11.4°S, 181.6°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the landforms from the left/upper left.
This digital elevation map shows the topography of the "Columbia Hills," just in front of the Mars Exploration Rover Spirit's current position. Rover planners have plotted the safest route for Spirit to climb to the front hill, called "West Spur." The black line in the middle of the image represents the rover's traverse path, which starts at "Hank's Hollow" and ends at the top of "West Spur." Scientists are sending Spirit up the hill to investigate the interesting rock outcrops visible in images taken by the rover. Data from the Mars Orbital Camera on the orbiting Mars Global Surveyor were used to create this 3-D map.
In figure 1, the digital map shows the slopes of the "Columbia Hills," just in front of the Mars Exploration Rover Spirit's current position. Colors indicate the slopes of the hills, with red areas being the gentlest and blue the steepest. Rover planners have plotted the safest route for Spirit to climb the front hill, called "West Spur." The path is indicated here with a curved black line. Stereo images from the Mars Orbital Camera on the orbiting Mars Global Surveyor were used to create this 3-D map.
In figure 2, the map shows the north-facing slopes of the "Columbia Hills," just in front of the Mars Exploration Rover Spirit's current position. Bright areas indicate surfaces sloping more toward the north than dark areas. To reach the rock outcrop at the top of the hill, engineers will aim to drive the rover around the dark areas, which would yield less solar power. The curved black line in the middle represents the rover's planned traverse path.
8 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows large, light-toned, ripple-like windblown bedforms in a portion of the giant flood channel complex, Maja Valles. Ripples such as these are very common on Mars but not very well understood. They are larger than most ripples on Earth, and smaller than typical dunes. They are usually old, and probably immobile, features. Sometimes, larger, dark sand dunes are seen riding over them (although that is not the case here). If similarly-sized ripples were to be investigated by a Mars rover, they would probably provide critical information that would help determine the nature of bedforms like these all over Mars. The Maja Valles scene shown here is located near 17.7°N, 54.8°W, and covers an area about 1.4 km (0.9 mi) wide. Sunlight illuminates the scene from the lower left.
13 August 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of the retreating seasonal south polar cap in the most recent spring in late 2003. Bright areas are covered with frost, dark areas are those from which the solid carbon dioxide has sublimed away. The center of this image is located near 76.5°S, 28.2°W. The scene is large; it covers an area about 250 km (155 mi) across. The scene is illuminated by sunlight from the upper left.
15 June 2004
Spring is upon the martian northern hemisphere, and the north polar cap is shrinking. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired on 12 June 2004, shows the retreating edge of the seasonal north polar cap near 70°N, 209°W. Low clouds and fogs stream away from the cap edge as it sublimes away. North is approximately up and the image covers an area roughly 500 km (311 mi) across. Sunlight illuminates the scene from the lower left. The crater containing a thick mound of material near the right-center of the image is Korolev.
9 December 2004
A century ago, the name Percival Lowell and the planet Mars were intimately linked through his popular writings about canals built by intelligent beings on the fourth planet. Today, a crater in the southern hemisphere of Mars is named for Lowell, who usually observed the planet from a hilltop in Flagstaff, Arizona. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in October 2004, shows a portion of a sand dune field in western Lowell Crater. The dunes are located near 51.3°S, 82.5°W. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
3 October 2004
When viewed at 100 to 300 meters per pixel in old Mariner 9 and Viking orbiter images, Warrego Valles appears to be a grouping of intricately-carved networks of branching valleys. This region has often been used as the type example of martian valley networks, and key evidence that Mars may have once been warmer, wetter, and perhaps had precipitation in the form of rain or snow. However, when viewed at very high resolution (1.5 to 4.5 meters per pixel) with the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), the Warrego valleys break down into a series of vaguely continuous (in other words, not necessarily connected to each other) troughs that have been covered and partially filled by a material that has eroded to form a very rough-textured surface. None of the original valley floor or wall features are visible because of this rough-textured mantle, and thus very little can be said regarding whether the valleys represent the results of persistent flow and precipitation runoff. Despite the MOC observations and the relatively unique nature of these valleys relative to other valley networks on Mars, the Warrego Valles continue to be used by many as an example of typical martian valley networks. The picture shown here is a mosaic of three MOC narrow angle images obtained in 1999 and 2004: M07-02071, R15-00492, and R15-02626. The dark bar near the bottom center is the location of a data drop, lost during transmission. The 1 km scale bar is approximately equal to 0.62 miles. Sunlight illuminates the images from the upper left, north is up, and the scene is located near 42.4°S, 93.5°W.
28 January 2006
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summer scene from the south polar region of Mars. The circular feature in the northeast (upper right) corner of the image is an old meteor impact crater that has been partially filled and buried. The cone-shaped hill that occurs within the crater on its east (right) side is a remnant of material that once covered and completely buried the crater. Perhaps beneath the surfaces in the rest of the image there are other craters that have been filled and buried such that we cannot know, from an image, that they ever existed. The theme of filled, buried, and exhumed craters is one that repeats itself -- over and over again -- all over Mars.
Location near: 80.3°S, 286.1°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Summer
8 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of small, dark sand dunes trapped along an arcuate ridge. The ridge probably marks the location of a partially-buried, eroded, and filled meteor crater. The dunes are located in Noachis Terra near 45.1°S, 322.0°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
26 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the most typical features of Isidis Planitia at full (1.5 meters -- 5 feet -- per pixel) resolution. The typical features are: (1) light-toned, ripple-like dunes and (2) mounds with summit pits. The dunes are formed by wind. The double-cone feature in the lower right quarter of the image is similar to many mounds and chains of mounds or cones found all across Isidis Planitia. These were seen at lower resolution in Viking orbiter images in the 1970s and were generally considered to be either small volcanoes or ice-cored mounds known as pingoes. With high resolution MOC images, it became apparent that many of these mounds may simply be the remnants of crater and pit chain floors, elevated above the surrounding plains as the layers of rock into which they formed were stripped away. Like much of Mars, there are more questions than answers. This image is located near 8.6°N, 268.2°W, and covers an area about 1.1 km (0.7 mi) wide. Sunlight illuminates the scene from the left/lower left.
14 May 2004
This March 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light- and dark-toned layered rock outcrops on the floor of Ritchey Crater, located near 28.9°S, 50.8°W. Some or all of these rocks may be sedimentary in origin. Erosion has left a couple of buttes standing on a more erosion-resistant plain. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
13 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows portions of two massifs composed of light-toned, sedimentary rock in Ganges Chasma, part of the Valles Marineris trough system. On the steeper slopes in this vista, dry talus shed from the outcrop has formed a series of dark fans. Surrounded by dark, windblown sand, these landforms are located near 8.6°S, 46.8°W. The image covers an area approximately 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.
1 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of semi-parallel ridges--yardangs--etched by wind into layered sedimentary rock on the floor of an unnamed crater in Terra Cimmeria. Many craters on Mars have been the sites of sedimentation. Over time, these sediments have become lithified. This picture is located near 31.3°S, 214.6°W. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the left/upper left.
29 January 2006
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a spotted, high latitude plain, south of the Argyre basin. When the image was received from Mars by the MOC operations team, they noticed -- with a sense of humor -- the number "8" on this martian surface. The "8" is located at the center-right and is formed by the rims of two old impact craters that have been eroded and partly-filled and partly-buried beneath the surface.
Location near: 68.6°S, 38.4°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Summer
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the odd patterns of erosion on the floor of Reull Vallis, a major valley system east of the Hellas Basin in the martian southern hemisphere. Somewhat circular features in this image may have once been meteor craters that were eroded and deformed by erosive processes. This image is located near 42.1°S, 254.5°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
3 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an exposure of finely-detailed layers in the martian north polar region. The polar ice cap, which is made up of frozen water (whereas the south polar cap is mostly frozen carbon dioxide), is underlain by a thick sequence of layers. Some have speculated that these layers may record the history of changes in martian climate during the past few hundreds of millions of years. This picture is located near 86.0°N, 30.2°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
24 October 2004
The northwest flanks of the broad, northern Tharsis volcano, Alba Patera, have been known since the 1970s to exhibit a plethora of what appeared to be branching valley networks running down the volcano slopes. Some investigators suggested that these valleys were evidence for precipitation and runoff of liquid water on the volcano flanks. It was hoped that high resolution images from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) would provide new details that would confirm or refute the hypothesis. The problem is, MGS MOC images instead showed a surface largely covered by an eroded, rough-textured mantle that obscured the valley floors. The images, such as the one shown here, also showed that the valleys are discontinuous and indistinct when viewed at high resolution (although, when shrunk to fit within the reduced-scale view on this web page, they may seem continuous -- click on the image to view the full-scale picture). The valleys in the lower quarter of this image have been cut by a fault. This image is located on Alba Patera near 45.8°N, 111.8°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
26 November 2004
This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a streamlined landform in the Mangala Valles region of Mars. An ancient catastrophic flood, probably consisting of water and debris, ran northward (from the bottom toward the top of the image) in this portion of the Mangala Valles system. The high mesa at the south end of the streamlined form may have been above the floodwaters. Its presence as an obstacle to the flow caused erosion and deposition of sediment to create the teardrop-shaped, tapered form in its lee. This feature is located near 15.0°S, 149.3°W. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
27 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows wind streaks and a thick mantling of dust in the summit region of the martian volcano, Pavonis Mons. The surface texture gives the impression that the MOC image is blurry, but several very small, sharp impact craters reveal that the picture is not blurry.
Location near: 1.1°N, 113.2°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Northern Summer
27 July 2004
Frost-covered dunes develop spots and streaks as they begin to defrost in springtime. This April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of north polar dunes in the early stages of the defrosting process. At the time the image was acquired, Mars was only 1 month into the northern spring season. The picture is located near 75.9°N, 266.0°W, and is illuminated by sunlight from the lower left. The image covers an area about 3 km (1.9 mi) wide.
30 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small volcano located southwest of the giant volcano, Pavonis Mons, near 2.5°S, 109.4°W. Lava flows can be seen to have emanated from the summit region, which today is an irregularly-shaped collapse pit, or caldera. A blanket of dust mantles this volcano. Dust covers most martian volcanoes, none of which are young or active today. This picture covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left.
26 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a scene in southern Galle Crater, otherwise known as Happy Face Crater. At the north end of the image (toward top, center) is a gully that formed on a slope. At the south end (bottom) is a series of dark sand dunes that have been crisscrossed by dust devils. The dust devils left behind tell-tale streaks. This image is located near 51.9°S, 31.6°W, and is illuminated by sunlight from the upper left. The image covers an area about 3 km (1.9 mi) wide.
1 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows streamlined islands and a small cataract in an outflow channel system in the Zephyria region of Mars, south of Cerberus. The fluids responsible for creating these landforms flowed from the lower left (southwest) toward upper right (northeast). The fluids may have been water and mud or, some Mars scientists have argued, extremely fluid lava. The presence of a small cataract probably argues more strongly for a water and mud origin. This image is located near 3.8°N, 204.7°W. The picture covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from upper left.
2 September 2004
This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows changes in dark wind streak patterns that occurred between 5 April 1999 (image M00-00534) and 17 August 2004 (image R20-00901). Unlike the spaghetti-like streak patterns made by dust devils, these streaks all begin on their upwind ends as tapered forms that fan outward in the downwind direction, and they all indicate winds that blew from the same direction. In both cases, winds blew from the southeast (lower right) toward the northwest (upper left). These streaks and the small pedestal craters found among them occur in the Memnonia region of Mars near 5.9°S, 162.2°W. The 400 meter scale bar is about 437 yards long. Sunlight illuminates each scene from the upper left.
12 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows buttes, craters, and exhuming impact craters in central Argyre Planitia. This wintertime view is illuminated by sunlight from the upper left and covers an area bout 3 km (1.9 mi) wide. The picture is located near 52.5°S, 42.6°W.
9 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes overlying an eroded, layered substrate in Chasma Boreale, amid the materials of the martian north polar cap.
Location near: 84.5°N, 358.3°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
4 March 2005
In honor of Giovanni V. Schiaparelli's 170th birthday, we present this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image showing light-toned dust devil streaks on the southern floor of Schiaparelli Crater.
Location near: 5.3°S, 343.3°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Autumn
6 September 2004
The Cerberus Fossae are a grouping of narrow troughs formed by extension and cracking of the martian crust in the region southeast of the Elysium volcanoes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small line of collapsed pits that follow the trend of the regional Cerberus Fossae troughs. These aligned pits show the location of a fault line that runs through the plains and cuts the low, rounded hill at the left, center of the image. This area is located near 7.5°N, 191.7°W. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this scene from the lower left.
24 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows collapse pits and troughs on the lower northeast flank of the giant martian volcano, Ascraeus Mons. Layers of volcanic rock are evident in some of the pit and valley walls, and boulders the size of houses and trucks that were liberated from these walls by gravity can be seen on the floors of the depressions.
Location near: 13.6°N, 102.6°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
28 September 2004
For the past several weeks, Mars was on the other side of the Sun relative to Earth. During this period, known as solar conjunction, radio communication with spacecraft orbiting and roving on Mars was limited. As is always done during solar conjunction, on 7 September 2004, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was turned off. On Saturday, 25 September 2004, the MOC team gathered at Malin Space Science Systems to command the instrument to turn back on again. After a successful turn-on, MOC acquired its first narrow angle camera image, shown here, on orbit 24808 (24,808th orbit since the start of the Mapping phase of the MGS mission in March 1999).
The 25 September image shows a portion of Nirgal Vallis, an ancient valley system in the Mare Erythraeum region of Mars. The valley floor is covered by large, ripple-like bedforms created by wind. This early southern winter image is located near 27.4°S, 42.9°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
This was the 4th solar conjunction period that MGS and MOC have been through since the spacecraft reached the red planet in September 1997. The four solar conjunction periods, where MOC was turned off, were:
First solar conjunction: 29 April - 1 June 1998 Second solar conjunction: 22 June - 12 July 2000 Third solar conjunction: 1 August - 18 August 2002 Fourth solar conjunction: 7 September - 25 September 2004.
In late October, MGS MOC will mark the start of its fourth Mars year since the beginning of the Mapping Phase of the mission in March 1999. MGS and MOC have already been orbiting Mars for more than 4 Mars years, including the pre-Mapping aerobrake and science phasing orbit insertion periods.
23 May 2004
The central peak of Oudemans Crater, located at the edge of the Labyrinthus Noctis trough system, consists of steeply-dipping rock layers that were uplifted and tilted by the meteor impact that formed the crater. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The banded features are layers of light-toned, possibly sedimentary, rock that were brought to the surface and uplifted by the impact process that formed the crater and its central peak. Oudemans Crater's central peak serves as a means for probing the nature of rock that lies beneath the plains cut by the Labyrinthus Noctis troughs, which are part of the vast Valles Marineris system. This March 2004 picture is located near 10.2°S, 92.0°W. The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
27 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired in October 2004, shows a portion of Arnus Vallis, a valley in northern Syrtis Major. Windblown sand has accumulated in the valley, forming dunes that are of a slightly lighter tone (higher albedo) than the surrounding terrain. This image is located near 15.1°N, 289.0°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
15 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the distal (far) end of a landslide deposit in Coprates Chasma, part of the vast Valles Marineris trough system. Large boulders, the size of buildings, occur on the landslide surface. This October 2004 picture is located near 15.3°S, 54.6°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
28 October 2004
This high resolution Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact crater with bouldery ejecta in the Arabia Terra region of Mars. The image is located near 11.9°N, 342.2°W. The 300 meter scale bar is about 328 yards long. Sunlight illuminates the scene from the upper left.
09 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the effects of severe wind erosion of layered sedimentary rock in the Aeolis region of Mars. The sharp ridges formed by wind movement from the lower left (southwest) toward top/upper right (northeast) are known as yardangs. The dark patches in the lower half of the image are sand dunes. This scene is located near 5.0°S, 203.7°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the terrain from the left/upper left.
24 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the results of erosion acting upon a layer of material in the south polar region of Mars. The elliptical pit in the lower left corner of the image was once buried beneath this eroding layer, as well. The processes that eroded the material, and the composition of the material, are unknown. The image is located near 80.7°S, 300.9°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates this scene from the top.
15 September 2004
Mars is a desert world. Today, wind is the most powerful agent of change. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows streak patterns made by wind as it distributed and re-distributed dark sediment across a light-toned substrate. This image is located west of Schiaparelli Crater near 1.0°S, 347.6°W, and covers an area approximately 3 km (1.9 mi) across. The scene is illuminated by sunlight from the left/upper left.
13 July 2004
Erosive winds have removed large volumes of material in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image to form yardang ridges. The most classic yardang shape is that of the inverted boat hull; each of these streamlined hills provides a near-textbook example. The landforms are found in the Medusae Sulci region near 5.7°S, 159.8°W. The image covers an area about 3 km (1.9 mi) wide, and is illuminated by sunlight from the lower left.
25 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an active dust devil making its way across the rugged terrain of the Loire Vallis system. The dust devil, seen as a fuzzy, nearly-circular bright feature near the center of the picture, is casting a shadow toward the right/upper right (east/northeast). Unlike some martian dust devils, this one did not make a dark streak on the ground. Many more dust devils occur on Mars than there are dust devil streaks observed on the planet's surface.
Location near: 18.2°S, 16.5°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Southern Spring
24 May 2004
Mariner 9 images acquired in 1972 first revealed a large, light-toned, layered mound in Ganges Chasma, part of the vast Valles Marineris trough system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a higher-resolution view of these rocks than was achieved by Mariner 9 or Viking, and higher than can be obtained by Mars Odyssey or Mars Express. The image, with a resolution of about 3.7 meters (12 feet) per pixel, shows eroded layered rock outcrops in Ganges Chasma. These rocks record a history of events that occurred either in Ganges Chasma, or in the rocks brought to the surface by the opening of Ganges Chasma. Either way, the story they might tell could be as fascinating and unprecedented as the story told by sedimentary rocks investigated this year in Meridiani Planum by the Opportunity Mars Exploration Rover ... no one knows. The image is located near 7.3°S, 48.8°W, and covers an area about 3 km (1.9 mi) across. The picture is illuminated by sunlight from the upper left.
18 May 2004
Mars is a desert planet, upon which wind has a great influence on the expression of its surface materials. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows large ripples (or small dunes) of windblown sediment among hills in the southeastern Cerberus region near 11.0°N, 199.5°W. Ripple orientations vary throughout the scene, indicating that dominant winds are influenced by the interplay of wind and local topographic features such as craters and hills. The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.
15 July 2004
The arrows in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture point to three boulders that left trails behind them as they rolled down the lower parts of a meteor crater's wall. In two cases, the tracks can be resolved into a series of small depressions, indicating the variable shape of the boulder as it unevenly proceeded down the slope. These features are located near 18.4°N, 120.1°W. The 75 meter scale bar is about 246 feet long. Sunlight illuminates the scene from the lower left.
07 August 2004
The springtime retreat of the north polar seasonal frost cap is progressing on schedule. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the state of defrosting north polar sand dunes just three days ago on 3 August 2004. Dark areas on the dunes are patches of bare sand; bright areas are remnants of frost deposited during the previous winter. Summer will arrive on 20 September 2004. These dunes are located near 76.3°N, 263.5°W. Their steepest slopes, known as the slip face of each dune, point toward the northeast (upper right), indicating wind transport of sand from the southwest (lower left). The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
22 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a cluster of impact craters, some of which damaged a portion of an old valley that runs roughly left to right in the lower half of the scene. The crater cluster most likely resulted from secondary impact of debris thrown from a much larger asteroid or comet impact, elsewhere on Mars. Large, light-toned, windblown ripples occur in many of the depressions in this portion of the Amenthes Fossae region. The picture is located near 7.3°N, 259.4°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the terrain from the left/upper left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows yardangs, formed by wind erosion, and large ripples formed in wind by deposition of sediment. The sharp yardang ridges trend from northwest toward southeast (upper left to lower right), while the ripple crests are nearly perpendicular to this trend.
Location near: 0.9°N, 212.5°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Northern Summer
8 September 2004
Presently Mars is experiencing late spring in its northern hemisphere, and dust devil activity is picking up as summer approaches. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of a cratered plain in southern Acidalia Planitia was acquired earlier this week on 5 September 2004. The arrow points to a dust devil observed that day. The image is located near 29.2°N, 30.3°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
27 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a field of dark sand dunes on the floor of an unnamed crater in western Arabia Terra near 7.3°N, 353.4°W. The dominant winds responsible for the movement of sand through this system blows almost directly north to south (top to bottom). The image covers an area about 3 km (1.9 mi) wide, and is illuminated by sunlight from the upper left.
8 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the interior of a typical crater in northern Acidalia Planitia. The floor is covered by material that forms an almost concentric pattern. In this case, the semi-concentric rings might be an expression of eroded layered material, although this interpretation is uncertain. The crater is located near 44.0°N, 27.7°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
24 December 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows Ascraeus Mons, the northernmost of the three Tharsis Montes shield volcanoes. Ascraeus Mons is about 460 km (~286 mi) across and its summit is at an elevation of about 18 km (11 mi) above the martian datum -- the elevation designated as 0 km. The center of the summit caldera is near 11°N, 104°W. Sunlight illuminates the scene from the left/upper left.
20 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a grouping of elongated, dark (low albedo) sand dunes in the north polar region of Mars. This picture was acquired during early summer in October 2004. The larger dune mass in this image may have accumulated through the coalescence of smaller dunes. These features are located near 85.7°N, 180.4°W. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
25 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a deeply eroded valley system in the western portion of the Olympica Fossae region of central Tharsis. The valleys may have been carved by water; today they are mantled by a thick blanket of dust, and small craters formed by meteor impacts superpose the valley landforms. This picture is located near 23.0°N, 117.2°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the left/lower left.
17 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark wind streaks formed by removal of a thin veneer of bright dust covering small craters and lava flow surfacesnorthwest of Olympus Mons near 28.4°N, 129.8°W. Streak orientations indicate that the responsible winds blew from the east/southeast (right/lower right) toward the west/northwest (left/upper left). The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates thescene from the lower left.
16 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the complex surfaces of some of the light- and intermediate-toned sedimentary rock exposed by erosion in eastern Sinus Meridiani. Similar rocks occur at the Mars Exploration Rover, Opportunity, site, but they are largely covered by windblown sand and granules. The dark feature with a rayed pattern is the product of a meteor impact.
Location near: 0.8°N, 355.2°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows an impact crater and associated bright wind streak in Acidalia Planitia. Dozens of smaller craters dot the scene.
Location near: 33.6°N, 25.0°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
15 October 2004
It is now early summer in the northern hemisphere on Mars, and this means that the ices of the north polar cap are in full retreat. Exposed from beneath seasonal frost are the eroded layers of what Mars scientists suspect are composed of a mixture of dust and ice (and in some layers, sand). This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the north polar layers exposed on a moderately-dipping slope. The bright material at the top of the image is water ice frost; the triangular features are thought to be caused by wind erosion of the frost. This image is located near 87.1°N, 267.4°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
4 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows exposures of layered material on slopes in the south polar region near 81.9°S, 72.2°W. Layers record the history of a place, but accessing the information contained in these layers may one day require a visit by a human or robotic explorer. The south polar layers, in general, are believed to be accumulations of dust and ice that were built up in the most recent billion years or so. However, they could just as easily be sedimentary rocks from much earlier in martian history. The picture covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
22 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical view of the martian northern plains. Thousands of square kilometers of the northern middle and polar latitudes of Mars look similar to the scene in this image. In late spring and in summer, dust devils crisscross the northern plains, leaving a variety of dark streaks. The streaks do not survive from year to year, indicating their ephemeral nature. The circular features in this image, including the prominent bright circular feature near the bottom, are the locations of buried meteor impact craters. This image is located near 58.1°N, 207.6°W, and covers an area approximately 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
1 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in a crater in Noachis Terra near 45.8°S, 323.4°W. Martian dunes, unlike the majority of their terrestrial counterparts, are dark because they are composed of minerals or rock fragments rich in unoxidized iron and magnesium. This image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates this autumn scene from the upper left.
28 January 2004
Northern Amazonis Planitia is famous for its frequent, large (> 1 km high) dust devils. They occur throughout the spring and summer seasons, and can be detected from orbit, even at the ~240 meters (~278 yards) per pixel resolution of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments. This red wide angle image shows a plethora of large dust devils. The arrow points to an example. Shadows cast by the towering columns of swirling dust point away from the direction of sunlight illumination (sun is coming from the left/lower left). This December 2004 scene covers an area more than 125 km (> 78 mi) across and is located near 37°N, 154°W.
19 January 2004
Covered by an eroded mantle of--perhaps--cemented dust, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part of a network of ancient valleys in northern Arabia Terra near Moreux Crater. The valleys may have originally been carved by a liquid such as water. The scene is located near 40.6°N, 316.4°W. The rugged surface of this mantled scene is a common feature at middle latitudes in both hemispheres of Mars. Some science investigators in the past several years have speculated that ice was once present in such mantles, and that the ice must have sublimed away to create the texture. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
6 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows several dark-toned mesas surrounded by light-toned sedimentary rock outcrops in Aram Chaos, a large impact basin -- over 200 km (more than 125 mi) across. These mesas are remnants of a once more extensive rock unit. The image is located near 2.0°N, 20.2°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
22 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows troughs and pits formed by collapse in the Gordii Fossae region, east of the volcano, Olympus Mons. Squiggly ridges with crests roughly aligned northwest-southeast (upper left to lower right), scattered throughout the image, are windblown dunes that have been covered by a mantling of dust. The image is located near 16.2°N, 125.3°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
1 January 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows Tikhonravov Crater in central Arabia Terra. The crater is about 386 km (240 mi) in diameter and presents two impact craters at its center that have dark patches of sand in them, giving the impression of pupils in two eyes. North (above) each of these two craters lies a dark-toned patch of surface material, providing the impression of eyebrows. M. K. Tikhonravov was a leading Russian rocket engineer in the 20th Century. The crater named for him, despite its large size, is still partly buried, on its west side, beneath the heavily cratered terrain of Arabia Terra. The center of Tikhonravov is near 13.5°N, 324.2°W. Sunlight illuminates the scene from the upper left.
20 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the wall on one of the calderae at the summit of the large volcano, Ascraeus Mons. A caldera is a large depression formed by collapse after magma in a volcano is erupted from or withdrawn to a greater depth. After collapse, the wall of this caldera was further modified by downslope movement of debris and it was pelted by small meteors to form a scattering of small craters. This image is located near 11.6°N, 104.6°W, and covers an area about 3 km (1.9 mi) across. The picture is illuminated by sunlight from the lower left.
3 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a high resolution view (nearly 1.8 meters; 6 feet per pixel) of landforms in the Granicus Valles region, west of the Elysium volcanoes. Layered rock and some large, dark boulders are among the features observed. The image is located near 27.4°N, 224.8°W, and covers an area only 1.1 km (0.7 mi) across. The scene is illuminated by sunlight from the lower left.
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows a butte and several other landforms eroded into light-toned, layered, sedimentary rock in southern Melas Chasma. Melas is part of the vast Valles Marineris trough system.
Location near: 11.8°S, 74.6°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: lower left
Season: Southern Spring
21 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows exposures of north polar layered material -- perhaps composed of a mixture of dust and ice--in the form of a hill and an adjacent depression. The depression is in the lower half of the image and forms an oval shape at its lowest elevations. The hill is immediately above the depression (above the center of the image) and forms a similar pattern of arcuate bands. This scene is located near 85.7°N, 21.0°W. The image covers an area approximately 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
25 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers broken-up by processes that form nearly square polygonal cracks and textures in the south polar region of Mars. Exactly how the polygons formed is anyone's guess; typically, polygon patterns in the martian polar regions are taken to indicate the presence of ground ice, similar to polygons in the Earth's arctic and antarctic regions. This picture is located near 86.4°S, 180.3°W, and is illuminated by sunlight from the upper left. The image covers an area about 3 km (1.9 mi) wide.
30 September 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wavy cloud pattern formed in the lee of Korolev Crater, located near 72.8°N, 195.7°W. Korolev Crater is about 85 km (53 mi) in diameter and named for Sergei P. Korolev, a pioneering Russian rocket designer and engineer who died in the mid-1960s. The image, acquired in late northern summer, is illuminated by sunlight from the lower left.
13 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in the north polar region of Mars. The dominant winds responsible for these dunes blew from the lower left (southwest). They are located near 76.6°N, 257.2°W. The picture covers an area 3 km (1.9 mi) across; sunlight illuminates the scene from the upper right.
22 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of sand dunes in a crater in Noachis Terra near 49.6°S, 352.9°W. Patches of autumn frost, possibly water ice, are seen on the south/southeastern (bottom/lower right) slopes of the dunes. This image mosaics with the east side of the dune image released as MOC Picture of the Day on 22 September 2004. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
10 February 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows low albedo sand dunes on the floor of a crater in southern Noachis Terra.
Location near: 52.5°S, 336.9°W
Image width: ~~3.0 km (~1.9 mi)
Illumination from: upper left
Season: Southern Autumn
4 December 2004
Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0°S, 311.9°W. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.
23 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned rock outcrops, possibly sedimentary rocks, in the Arsinoes Chaos region east of the Valles Marineris trough system. These rocky materials were once below the martian surface. These features are located near 7.2°S, 27.9°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
25 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows buttes composed of light-toned, sedimentary rock exposed by erosion within a crater occurring immediately west of Schiaparelli Basin near 4.0°S, 347.9°W. Surrounding these buttes is a field of dark sand dunes and lighter-toned, very large windblown ripples. The sedimentary rocks might indicate that the crater interior was once the site of a lake. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
11 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures some of the complexity of the martian upper crust. Mars does not simply have an impact-cratered surface, it's upper crust is a cratered volume. Over time, older craters on Mars have been eroded, filled, buried, and in some cases exhumed and re-exposed at the martian surface. The crust of Mars is layered to depths of 10 or more kilometers, and mixed in with the layered bedrock are a variety of ancient craters with diameters ranging from a few tens of meters (a few tens of yards) to several hundred kilometers (more than one or two hundred miles).
The picture shown here captures some of the essence of the layered, cratered volume of the upper crust of Mars in a very simple form. The image shows three distinct circular features. The smallest, in the lower right quarter of the image, is a meteor crater surrounded by a mound of material. This small crater formed within a layer of bedrock that once covered the entire scene, but today is found only in this small remnant adjacent to the crater. The intermediate-sized crater, west (left) of the small one, formed either in the next layer down--that is, below the layer in which the small crater formed--or it formed in some layers that are now removed, but was big enough to penetrate deeply into the rock that is near the surface today. The largest circular feature in the image, in the upper right quarter of the image, is still largely buried. It formed in layers of rock that are below the present surface. Erosion has brought traces of its rim back to the surface of Mars. This picture is located near 50.0°S, 77.8°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this October 2004 image from the upper left.
26 February 2005
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows light-toned sedimentary rock outcrops and large dark-toned, windblown ripples in Aram Chaos.
Location near: 3.0°N, 20.9°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Northern Summer
22 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows details among some of the eroded layer outcrops of the martian south polar region. Much of the south polar region of Mars is covered by a thick unit of layered material. For decades, the layers have been assumed to consist of a mixture of dust and ice, but it is equally possible that the materials are sedimentary rocks. This image was captured during southern spring, at a time when some of the surface was still covered by seasonal carbon dioxide (CO2) frost.
Location near: 86.5°S, 116.6°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Spring
10 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an ancient valley in far northwestern Arabia Terra, near the Cydonia region. Large, windblown ripples occur on the valley floor. This valley is located near 33.2°N, 10.1°W. The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the left/lower left.
29 August 2004
Most southern high latitude dune fields occur on the floors of impact craters, and many of them are eroded into rounded or flattened forms. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of dunes (southern half of image) and a relatively flat sand sheet (northern half of image) in a crater located near 63.9°S, 95.9°W. Wind transport of sand was from the right toward left (east to west). Dark streaks superimposed on the dunes are the tracks made by passing dust devils. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.
2 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows details near the front edge of a lava flow in the Daedalia Planum region. Daedalia Planum is a vast region covered with the extremely large lava flows of southern Tharsis. The trough in the lower third of the image is a graben formed by extension and faulting of the martian crust. This image is located near 28.1°S, 135.0°W, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
6 November 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact crater (approximately the size of the famous Meteor Crater in northern Arizona) with a bright wind streak on its west (left) side. Generally, winds blowing from the east (right) have stripped away bright dust everywhere but in the lee of the crater. These landforms are located in eastern Kasei Valles near 25.1°N, 60.8°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left/lower left.
2 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows raised-rimmed, circular features sometimes described as "boulder rings." These are located on the vast martian northern plains, and they are, basically, somewhat filled and somewhat buried meteor impact craters. The small, dark dots on these rings are boulders derived from the craters' ejecta and perhaps from erosion of the rock in which the craters formed. This image is located near 70.4°N, 310.4°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
3 September 2004
On 3 September 2004, the 28th anniversary of the Viking 2 landing on Mars, we take a look back only 9 months at another place where a U.S. spacecraft landed on the red planet. This oblique red wide angle camera image obtained by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows the proximity of the Mars Exploration Rover (MER-A), Spirit, landing site in Gusev Crater to the martian volcano, Apollinaris Patera. The January 2004 Spirit landing site is indicated by the white circle at the bottom (south end) of the image. The volcano covers most of the upper (northern) half of the picture. The volcano's summit depression, or caldera is about 73 kilometers (~45 miles) across. This perspective view was obtained in June 2004 by MOC as MGS was beginning to roll so as to point the camera at a target located further north. The Spirit landing site is located near 14.8°S, 184.6°W. Sunlight illuminates this scene from the upper left.
27 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the layered, sedimentary rock outcrops that occur in a crater located at 8°N, 7°W, in western Arabia Terra. Dark layers and dark sand have enhanced the contrast of this scene. In the upper half of the image, one can see numerous lines that off-set the layers. These lines are faults along which the rocks have broken and moved. The regularity of layer thickness and erosional expression are taken as evidence that the crater in which these rocks occur might once have been a lake. The image covers an area about 1.9 km (1.2 mi) wide. Sunlight illuminates the scene from the lower left.
13 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows north polar sand dunes in the summertime. During winter and early spring, north polar dunes are covered with bright frost. When the frost sublimes away, the dunes appear darker than their surroundings. To a geologist, sand has a very specific meaning. A sand grain is defined independently of its composition; it is a particle with a size between 62.5 and 2000 microns. Two thousand microns equals 2 millimeters. The dunes are dark because they are composed of sand grains made of dark minerals and/or rock fragments. Usually, dark grains indicate the presence of unoxidized iron, for example, the dark volcanic rocks of Hawaii, Iceland, and elsewhere. This dune field is located near 71.7°N, 51.3°W. Dune slip faces indicate winds that blow from the upper left toward lower right. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
19 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact crater, about 90 meters (~295 feet) in diameter, with a short, dark wind streak on its down-wind side. The crater is located atop south polar layered materials near 80.2°S, 210.4°W. The March 2004, early autumn picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
11 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows small buttes and irregular mesas on the floor of a crater in the Nili Fossae region of Mars. Considerable erosion in the Nili Fossae region has exposed layered rocks and stripped materials away, revealing long-buried landforms and more ancient landscapes. This image is located near 24.3°N, 279.8°W. It covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.
12 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcroppings of a light-toned rock layer on the lower slopes of buttes, hills, and massifs within one of the depressions of the Labyrinthus Noctis (Labyrinth of Night) system of the western Valles Marineris. The layer was once continuous across the area. The image is located near 7.5°S, 96.1°W, and covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
14 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a gullied crater wall at 1.5 meters (5 feet) per pixel resolution. The gullies in this case have formed in a thick, smooth-surfaced mantle that covers the crater wall. Formation of these gullies might have involved a fluid such as water, or perhaps could have formed by avalanching of dry debris. The Mars science community is still discussing, debating, and making new observations of martian gullies to better understand their origin and implications. These gullies are located near 33.8°S, 201.6°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
10 December 2004
The lower left (southwest) corner of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the location of a somewhat filled and buried meteor impact crater on the northern plains of Mars. The dark dots are boulders. A portion of a similar feature is seen in the upper right (northeast) corner of the image. This picture, showing landforms (including the odd mound north/northeast of the crater) that are typical of the martian northern lowland plains, was obtained as part of the MGS MOC effort to support the search for a landing site for the Phoenix Mars Scout lander. Phoenix will launch in 2007 and land on the northern plains in 2008. This image is located near 68.0°N, 227.4°W, and covers an area approximately 3 km (1.9 mi) wide. The scene is illuminated by sunlight from the lower left.
21 October 2004
Near the center of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image lies the degraded remnants of an old meteor impact crater. The terrain in which it occurs is a heavily eroded, north middle-latitude surface. The image is located in the fretted terrains north of Arabia Terra near 41.3°N, 305.8°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.
22 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of dark sand dunes that formed in winds blowing from east (right) to west (left), along with smaller, lighter-toned ripples and many dark dust devil tracks. The dust devil tracks indicate movement from a variety of directions, while the dunes only indicate winds from the east. In the lower left quarter of the image, dune sand has flowed around a layered rock obstacle. This scene is located near 19.9°N, 280.5°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the lower left.
13 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies emergent from beneath erosion-resistant rock layers in a trough south of Atlantis Chaos near 38.9°S, 176.3°W. Gullies such as these are fairly common in depressions at south middle latitudes. Tens of thousands of gullies have been identified in MGS MOC and Mars Odyssey Thermal Emission Imaging System (THEMIS) images. Whether they formed by running liquid water remains a controversial issue. Banked channels, like some shown here, are one form of evidence cited to indicate that a fluid with the properties of liquid water may have been involved. This image covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.
7 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered outcrops of sediment deposited in southern Chryse Planitia by flow through the Hypanis Valles system in Xanthe Terra. The distinct inverted boat hull-shaped ridges are yardangs formed by wind erosion. These materials are located near 11.9°N, 45.5°W. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the left/lower left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered rock outcropping in a pit on the lower west flank of Arsia Mons, one of the large Tharsis shield volcanoes. Given their location, these layers are very likely dominated by volcanic rocks, including lava flows. This depression is located near 8.8°S, 123.7°W. The image covers an area about 4.8 km (3 mi) wide and is illuminated by sunlight from the lower right.
20 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, barchan sand dunes of the north polar region of Mars. Barchan dunes are simple, rounded forms with two horns that extend downwind. Inequalities in local wind patterns may result in one horn being extended farther than the other, as is the case for several dunes in this image. The image also shows several barchans may merge to form a long dune ridge. The horns and attendant slip faces on these dunes indicate wind transport of sand from the upper left toward the lower right. The image is located near 77.6°N, 103.6°W. The picture covers an area about 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
29 January 2004
Northern Amazonis Planitia is famous for its frequent, large (> 1 km high) dust devils. They occur throughout the spring and summer seasons, and can be detected from orbit, even at the ~240 meters (~278 yards) per pixel resolution of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments. This red wide angle image shows a plethora of large dust devils. The arrow points to an example. Shadows cast by the towering columns of swirling dust point away from the direction of sunlight illumination (sun is coming from the left/lower left). This December 2004 scene covers an area more than 125 km (> 78 mi) across and is located near 37°N, 154°W.
17 August 2004
This July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of aligned barchan sand dunes in the martian north polar region. At the time, the dunes were covered with seasonal frost, but the frost had begun to sublime away, leaving dark spots and dark outlines around the dunes. The surrounding plains exhibit small, diffuse spots that are also the result of subliming seasonal frost. This northern spring image, acquired on a descending ground track (as MGS was moving north to south on the "night" side of Mars) is located near 78.8°N, 34.8°W. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.
25 December 2004
For 25 December, the MOC team thought that a visit to a north polar site would be timely. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows, at about 1.5 meters per pixel (~5 feet per pixel) resolution, a view of the north polar ice cap of Mars. That the material includes water ice has been known since the mid-1970s, when Viking orbiter observations confirmed that the cap gives off water vapor in the summertime, as the ice is subliming away. The surface shown here, observed by MOC during northern summer in November 2004, is pitted and somewhat grooved. Dark material on pit floors might be trapped, windblown dust. The picture covers an area about 1 km (0.62 mi) across, and is located near 86.8°N, 293.1°W. Sunlight illuminates the scene from the lower left.
21 July 2004
Dark slope streaks are a common feature on slopes thickly-mantled by dust, especially in the Tharsis, Arabia, and western Amazonis regions of Mars. Less common are light-toned slope streaks, which often occur in the same area as dark streaks. They are most common in Arabia Terra, and some are shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Slope streaks are probably the result of sudden avalanches of extremely dry dust. The behavior of the avalanching dust is somewhat fluid-like, and new streaks have been observed to form over intervals of a few months to a Mars year. This image is located near 13.4°N, 340.3°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
26 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygonal patterned ground on a south high-latitude plain. The outlines of the polygons, like the craters and hills in this region, are somewhat enhanced by the presence of bright frost left over from the previous winter. On Earth, polygons at high latitudes would usually be attributed to the seasonal freezing and thawing cycles of ground ice. The origin of similar polygons on Mars is less certain, but might also be an indicator of ground ice.
Location near: 75.3°S, 113.2°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Spring
23 July 2004
Acquired just a few days ago on 21 July 2004, this 1.7 m/pixel (5.6 ft/pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layer outcrops and sand dunes in the Chasma Boreale portion of the martian north polar cap. At this time, it is spring and these polar landforms are still covered by frost left over from the winter that ended back in March 2004. In summer, the dunes in this image will be darker than anything else in the scene. The picture is located near 85.1°N, 3.7°W, and covers an area about 1.5 km (0.9 mi) wide. This view is illuminated by sunlight from the upper right.
20 October 2004
This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the fretted terrain north of eastern Arabia Terra. As described earlier this month in "Craters in Fretted Terrain," the fretted terrains of Mars are the broken-up, blocky areas where the heavily cratered martian highlands transition to the lightly-cratered, lower elevation, northern plains. The landforms in the top half of the picture shown here comprise a portion of the fretted terrain. This picture has a resolution of about 243 meters (266 yards) per pixel and covers an area about 248 kilometers (154 miles) wide. The long valley that runs diagonal from lower center toward right center in the bottom half of the picture is Auqakuh Vallis. This image is located near 32°N, 299°W, and is illuminated by sunlight from the left/lower left. Another view of landforms in the fretted terrain was featured yesterday in "Fretted Terrain Craters."
7 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a mid-summer view of the south polar residual cap at full MOC resolution, 1.5 m (5 ft) per pixel. During each of the three summers since the start of the MGS mapping mission in March 1999, the scarps that form mesas and pits in the "Swiss cheese"-like south polar terrain have retreated an average of about 3 meters (~1 yard). The material is frozen carbon dioxide; another 3 meters or so of each scarp is expected to be removed during the next summer, in late 2005. This image is located near 86.0°S, 350.8°W, and covers an area about 1.5 km (0.9 mi) wide. Sunlight illuminates the scene from the top/upper left.
22 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of north polar dunes in late spring, just before the final patches of wintertime frost sublimed away. The dunes beneath the frost are dark because they contain minerals rich in reduced (unoxidized) iron. The dune slip faces (the steepest slopes on the dunes) point toward the upper right (northeast), indicating that the dominant winds involved in sand transport in this region blow from the lower left (southwest). These dunes are located near 76.3°N, 261.1°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.
2 January 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a depression eroded into north polar layered materials located near 86.1°N, 30.8°W. The layers in the north polar region have been considered for more than 30 years to be composed of dust and ice, although this cannot be confirmed without sending a person or robot to investigate. This picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
2 June 2004
This 1.5 meters (5 ft.) per pixel Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of gullies and dunes in a crater near Gorgonum Chaos was acquired in late May 2004. The gullies may have formed by a combination of processes. Many middle- and polar-latitude gullies such as these are thought to form both by mass movement of dry materials and action of liquid water. Some investigators suggest alternative fluids such as carbon dioxide. Still others make a case that no fluid was involved at all. Some gullies on Mars show clear association with subsurface layering and undermining of those layers; they also show banked channels; these kinds of observations are usually taken in support of the water hypothesis. The crater in which the landforms shown here occur is located at 37.5°S, 169.3°W. This image covers an area about 1.5 km (0.9 mi) across. The scene is illuminated by sunlight from the upper left.
This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows sand dunes in the north polar region of Mars, as they appeared during northern summer in December 2004.
Location near: 78.1°N, 227.2°W
Image width: ~3.0 km (~1.9 mi)
Illumination from: lower left
Season: Northern Summer
20 November 2004
Both the north and south polar ice caps overlie a thick accumulation of layered material. For more than three decades, these deposits have been assumed to consist of a mixture of dust and ice. This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the north polar layers exposed on a slope located near 79.1°N, 348.4°W. The image covers an area approximately 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
5 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows alternating light and dark wind streaks superimposed over a rugged lava flow surface on the west flank of the volcano, Ascraeus Mons. A chain of pits in the upper half of the image mark the location of a collapsed lava tube. The image is located near 11.6°N, 105.5°W, and covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.
14 October 2004
Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images exhibit wild patterns of dark streaks thought to have formed by the passage of many dust devils. The dust devils disrupt the dust coating the martian surface, leaving behind a streak. However, not all dust devils make streaks, and not all dust devil streaks are dark. Some are light---it simply depends upon which is darker, the substrate or the dust that the spinning vortex disrupts. The example of light-toned dust devil streaks shown here is located in southern Schiaparelli Basin near 5.3°S, 343.3°W. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left/upper left.
29 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.5 meters (5 feet) per pixel view of a large collapse pit (and portions of several smaller pits) in the Tractus Fossae portion of the Tharsis region of Mars. Such collapses usually occur along faults formed by expansion and pulling apart of the planet's upper crust.
Location near: 22.5°N, 101.4°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn
18 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a trough in the Stygis Catena region east of the martian volcano, Elysium Mons. The trough probably formed by collapse. Large, dark boulders can be seen on the trough floor in this volcanic region. The image is located near 24.4°N, 210.4°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.
26 August 2004
Eastern Arabia Terra shares many attributes with western Arabia and Sinus Meridiani. In particular, it is a region of vast layered rock within which are interbedded filled and buried craters and valleys. Erosion has subsequently re-exposed many of these landforms, including the exhumed and eroded crater shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Following the period in which erosion occurred, the region was blanketed by dust. This image is located near 22.5°N, 318.4°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the left/lower left.
12 October 2004
Although one might argue that most of the "i" is missing, and part of the "h" has been eroded away, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned sedimentary rock outcrops in northern Sinus Meridiani that almost seem to spell out the word, "hi." This natural graffiti is all that remains of a suite of sedimentary rock that once covered the area shown here. The 400 meter scale bar is about 437 yards long. The features are located near 1.8°N, 357.2°W. Sunlight illuminates the scene from the upper left.
Voir l'image PIA06932: Mars Says "hi"! sur le site de la NASA.
16 July 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the layered rocks and boulders exposed on the wall of a trough in the Terra Sirenum region. The layers that erode to produce large boulders are harder and more resistant to weathering and erosion than those that do not. The slope is located near 25.8°S, 139.8°W. The image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
13 October 2004
This August 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lava flows and a collapsed lava tube on the upper southwest flank of Olympus Mons, one of the largest volcanoes ever known. The collapsed lava tube is the channel-like feature in the upper third of the image. All of the surfaces in this image are very heavily peppered by small meteor impact craters. While fairly young relative to much of the martian surface, the large volcanoes of Mars are still quite old and battered by impacts. This image is located near 17.9°N, 135.4°W, and image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.
9 July 2004
The processes that have eroded and exposed sedimentary rock outcrops in many of the Valles Marineris troughs are unclear. However, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from western Tithonium Chasma that is unambiguous. The ridges are yardangs, an erosional form created by wind. To acquire the characteristic shape of a yardang, the material being eroded must contain some amount of sand. As weathering processes loosen sand grains from the outcrop, they become available to be picked up and transported away by wind. In the case shown here, the dominant, rock-eroding winds came from the top/upper right (north). This view of eroded sedimentary rock in western Valles Marineris is located near 4.6°S, 89.1°W. At 1.5 meters (5 feet) per pixel, this image covers an area about 3 km (1.9 mi) wide, and is illuminated by sunlight from the left.
23 December 2004
The Mars Exploration Rover (MER-B), Opportunity, spent much of this year exploring outcrops of light-toned, layered, sedimentary rock that occur just beneath the dark plains of Sinus Meridiani. To access these rocks, the rover had to look at the walls and rims of impact craters. Further to the north and east of where the rover landed, similar rocks outcrop at the surface -- in other words, they are not covered by dark sand and granules as they are at the rover site. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from eastern Sinus Meridiani. All of the light-toned surfaces in this image are outcrops of ancient sedimentary rock. Similar rocks probably occur beneath the low albedo (dark) materials that mantle the lower-elevation surfaces in this area. This picture is located near 0.5°S, 356.7°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the upper left.
19 December 2004
Most craters on the martian northern lowland plains are filled and many of them are buried just beneath the surface, or are mostly buried. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example, in which only the crater's raised rim still pokes out above the surrounding plains. This crater is located near 46.2°N, 257.7°W. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.
19 August 2004
The arrows (see Figure 1) in this July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image indicate the location of an unconformity in the layered sequence of the martian north polar cap. An unconformity is a geologic term that indicates a break in the depositional record of a sedimentary deposit. In this case, the change is recorded by the presence of a series of polar layers that are truncated (cut off) along the line of arrows. The erosion that cut these layers along a gentle slope were later covered by a new set of layers that occur from the arrow tips upward to the top of the sequence shown here. The image is located near 85.2°N, 7.3°W. The bright features in the lower third of the image are frost-covered sand dunes. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the top/upper right.
4 October 2004
Robert P. Sharp in a classic Journal of Geophysical Research paper, the fretted terrains of Mars are those in which, at about 200 to 400 meters per pixel scale, have "smooth, flat lowland areas separated from a cratered upland by abrupt escarpments" approximately 1 to 2 km (0.6 to 1.2 mi) high. As viewed from above, the fretted terrain troughs are nearly straight and carve-up old, heavily cratered terrain just north of Arabia Terra and part of northern Tempe Terra. The trough floors in the northern mid-latitude fretted terrain are heavily eroded. These floors were thought, on the basis of Viking orbiter images, to possibly have glaciers or some other form of flowing or creeping ground ice. However, Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images have shown little evidence for flow on these pitted and lineated floors. Circular features that were probably once meteor impact craters have not been sheered or deformed, as they would have been if the material were flowing.
The MOC image shown here exhibits a few examples of the eroded forms of old craters on the floor of a fretted terrain valley. Crater 1 still retains the typical bowl shape of an impact crater, but its raised rims and ejecta blanket have been eroded away. Crater 2 is a shallow depression that might also represent the location of a meteor crater that has nearly eroded away. Feature 3 is a circular mesa; it is probably all that remains of a crater that was filled then eroded away, leaving behind a remnant of the material that filled the crater. Feature 4 is a small depression with a central mound--this, too, may have been an impact crater and the mound is a remnant of material that once filled the crater. In all, erosion appears to have been powerful enough to remove material that once existed above the present landscape, and altered the appearance of craters in this region.
The image is located near 40.2°N, 335.2°W. The 300 m scale bar is also about 985 ft across. Sunlight illuminates the scene from the lower left. The R. P. Sharp paper described here is, "Mars: Fretted and chaotic terrain," Journal of Geophysical Research,v. 78, n. 20, p. 4073-4083, 1973.
7 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.4 m/pixel (~5 ft/pixel) view of a typical martian north polar ice cap texture. The surface is pitted and rough at the scale of several meters. The north polar residual cap of Mars consists mainly of water ice, while the south polar residual cap is mostly carbon dioxide. This picture is located near 85.2°N, 283.2°W. The image covers an area approximately 1 km wide by 1.4 km high (0.62 by 0.87 miles). Sunlight illuminates this scene from the lower left.
17 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows low, broad sand dunes and sheets in southern Briault Crater near 10.1°S, 270.7°W. In this case, winds have swept up all available sand in Briault Crater, and moved it toward the south side of the basin. The wind streak pattern of these landforms indicates that the dominant winds blow from the north (top) toward the south. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.
08 August 2004
The martian atmosphere is an artist. It uses narrow vortices of spinning air to disrupt thin coatings of dust on the surface. In some regions, over time, hundreds of dust devils may streak across the landscape, creating patterns like the one shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. The picture, acquired in February 2004, is located near 64.1°S, 297.3°W, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.
3 August 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows mesas and buttes on the floor of a depression in the Labyrinthus Noctis region of Mars. This is part of the western Valles Marineris. Each mesa is a remnant of a formerly more extensive sequence of rock. The image is located near 7.0°S, 99.2°W. It covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the lower left.
23 June 2004
The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) captured this chance view of a dust devil (left of the center of the picture) near 2 p.m. local Mars time on 12 April 2004, in western Tithonium Chasma. The dark splotch to the right of the dust devil is its shadow. Sunlight illuminates the scene from the left/upper left. Tithonium is one of the troughs of the Valles Marineris system. The picture is located near 4.7°S, 89.1°W, and covers an area about 3 km (1.9 mi) wide.
14 November 2004
The Kasei Valles are a suite of very large, ancient outflow channels. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the youngest channel system in the Kasei Valles. Torrents of mud, rocks, and water carved this channel as flow was constricted through a narrow portion of the valley. Layers exposed by the erosion that created the channel can be seen in its walls. This 1.4 meters (5 feet) per pixel image is located near 21.1°N, 72.6°W. The picture covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
29 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows steep slopes of light-toned rock and dark windblown sand in eastern Candor Chasma, part of the vast Valles Marineris trough system. The rock is probably sedimentary. In a few places, rock has broken down and slid downslope to create a narrow chute and a pile of talus where the slope meets the adjacent dark, dune-covered plain. This image is located near 7.8°S, 64.9°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
11 August 2004
Acquired just last week on 3 August 2004, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark, layered scarp in the martian north polar region. All of the light-toned surfaces in this image are covered by frost left over from the previous winter. On the scarp, about half of the surfaces once covered by frost are now exposed (as the frost has sublimed away), leaving a large number of bright patches. These patches of frost enhance the appearance of layering on the slopes. This image is located near 81.8°N, 84.4°W. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the lower left.
25 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a series of pits running down the center of a broad, shallow trough called a graben. On Mars, many such troughs, and attendant pits, are the result of geologic forces that extended the crust as the Tharsis region of Mars bulged outward to form what is known as, well, the Tharsis Bulge. This graben and pit chain are located near the Rhabon Valles around 23.8°N, 92.3°W. The image covers an area about 3 km (1.9 mi) wide; sunlight illuminates the scene from the lower left.
14 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a channel in the Marte Valles outflow system. An old meteor impact crater in the lower left (southwest) corner of the image blocked the erosive fluids that poured through Marte Vallis, creating a streamlined tail in its lee. The materials that flowed through the valley may have been water-rich mud, very fluid lava, or both. The nature of the fluid is still a matter of research and discussion among Mars scientists. This image is located near 12.5°N, 177.5°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.
25 May 2004
From time to time, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) catches--in action-an afternoon dust storm, dust devil, or other dust-raising event. The dust-raising event shown here, probably the result of a sudden strong gust of wind, occurred in November 2003 in a crater located near 57.5°S, 60.6°W. Sunlight illuminates the scene from the upper left, so the dark area below the dust plume is its shadow. The picture covers an area about 3 km (1.9 mi) across.
5 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of dark, windblown sand dunes in the Noachis Terra region near 45.2°S, 321.4°W. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this scene from the upper left.
13 September 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows about two dozen circular depressions, each with a circular mesa on its floor. These were once meteor impact craters. The craters were filled with layered material, buried, and then exhumed and eroded. The dark, elliptical feature in the lower left (southwest) corner of the image is a butte composed of the layered rock that once completely covered the craters in this image. These landforms are located in a depression eroded into the floor of a much larger, partially-filled impact crater located near 35.1°S, 356.5°W. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.
30 July 2004
This full-resolution (1.5 meters, 5 feet, per pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fairly small, fresh meteor impact crater in far southeastern Arabia Terra. The crater's bowl, rim, and ejecta exhibit numerous boulders. The image covers an area about 3 km (1.9 mi) wide and is located near 6.9°S, 317.1°W. Sunlight illuminates the terrain from the left.
22 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, windblown ripples on the floors of channels of the Apsus Vallis system. The fluid responsible for forming the valleys is unknown; it might have been water. No primary landforms, other than the channels themselves, have been preserved in a way that would indicate the nature of the fluid that carved the valleys. Apsus Vallis is located just west of the Elysium volcanic region; the area in the picture is located near 35.5°N, 225.6°W. The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.
23 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small, springtime dust devil creating a dark streak on the plains of Argyre. The small, bright dot is the dust devil. Many other dark streaks on the plains indicate the areas where other dust devils had passed within the past several weeks before this July 2005 image was acquired.
Location near: 44.6°S, 40.3°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Southern Spring
17 November 2004
Mars was once a much wetter world than it is today. Locked within the martian bedrock are ancient channels and valleys through which liquids -- e.g., water -- once flowed. In the Aeolis region of Mars, wind erosion has exposed and inverted a plethora of ancient channels - stream beds -- in a fan-shaped sedimentary rock unit near 6.3°S, 208.6°W. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The smooth-looking, sinuous ridges that run left-right across the image are the inverted channels. The rugged, sharp-looking ridges that run nearly north-south (up-down) through the image are yardangs--ridges formed by wind erosion. The water (or other liquid) responsible for the original channels flowed from the left (west) to right/upper right (east/northeast). This scene covers an area approximately 3 km (1.9 mi) across, and is illuminated by sunlight from the upper left.
7 March 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a lava channel on the northeastern summit of Ascraeus Mons.
Location near: 11.5°N, 104.2°W
Image width: ~3 km (~1.9 mi)
Illumination from: upper left
Season: Northern Spring
26 October 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows terrain in northwestern Argyre Planitia during southern autumn in August 2004. Several mesas stand high above a rippled plain. Argyre is a very ancient and heavily modified impact basin. The ripple patterns were probably formed from windblown sediment. This image is located near 47.1°S, 45.6°W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of layered sedimentary rock in a crater in northwestern Schiaparelli basin was acquired using the cPROTO technique described previously on 27 September 2004. MOC cPROTO images provide rare glimpses of the martian surface at the highest resolution ever achieved from orbit--in this case, nearly 50 centimeters (~20 inches) per pixel. The finely-layered rock shown here, and the repeated nature of the layers in the rock, are clues that these sediments may have been deposited in an intracrater lake.
Location near: 0.2°S, 345.7°W
150 m scale bar = ~164 yards
Illumination from: upper right
Season: Southern Summer
