Mission Mars Global Surveyor - 7

<h1>PIA04638: Southern Auqakuh Vallis</h1><div class="PIA04638" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-421, 14 July 2003<p>Auqakuh Vallis located in northeastern Arabia Terra, an eroded, cratered highland terrain. Because erosion has removed hundreds of meters (or more) of material from the terrain surrounding Auqakuh Vallis, the valley today appears to be much shallower and wider than it was when it formed. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a shallow reach of the valley at its southernmost extent. The valley floor runs east-west (left-right) across the center of this picture. The floor of the valley has several dozen large, windblown ripples on it. The surrounding terrain has been eroded to form mesas and a few nearly-straight ridges known as dikes. This picture, acquired in July 2003, is located near 27.7°N, 298.0°W. The image covers an area 3 km (1.9 mi) across and is illuminated from the lower left.<p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04638" onclick="window.open(this.href); return false;" title="Voir l'image PIA04638: Southern Auqakuh Vallis sur le site de la NASA">Voir l'image PIA04638: Southern Auqakuh Vallis sur le site de la NASA.</a></div>
PIA04638: Southern Auqakuh Vallis
<h1>PIA04639: South Polar "Poodle"</h1><div class="PIA04639" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-422, 15 July 2003<p>Have you ever stared up at the clouds in the sky and seen the shapes of animals, people, or objects? Sometimes when the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) team is looking at newly-returned pictures from Mars, the same thing happens. This is a picture of pits and scarps in the frozen south polar carbon dioxide ice cap. Sunlight illuminates the scene from the upper right. At the bottom of the picture is a feature that resembles a long, thin poodle; its head faces to the left, the tail to the right. This picture is located near 86.9°S, 55.8°W.<p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04639" onclick="window.open(this.href); return false;" title="Voir l'image PIA04639: South Polar "Poodle" sur le site de la NASA">Voir l'image PIA04639: South Polar "Poodle" sur le site de la NASA.</a></div>
PIA04639: South Polar "Poodle"
<h1>PIA04641: Crater with Wavy Fog</h1><div class="PIA04641" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-424, 17 July 2003<p>Craters near the edge of the retreating south polar seasonal frost cap often have fog in them, this time of year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image was acquired just a few days ago on July 13, 2003. It shows a crater, 36 km (22 mi) across, that is enveloped in fog. This picture was taken as a context frame for a high resolution view that was intended to show dunes on the floor of the crater. That high resolution view was frustrated by thick fog that hid the dunes from view. This wide angle context frame shows that winds from the lower right (southeast) were blowing over the crater, causing the fog to bunch up in a wavy, rippled pattern. Winds streaming off the polar cap toward the north create a variety of patterns in the fogs formed by water ice or vapor as the seasonal cap retreats during southern spring. This picture is located at 66.4°S, 208.6°W, sunlight illuminates the scene from the upper left (northwest).<p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04641" onclick="window.open(this.href); return false;" title="Voir l'image PIA04641: Crater with Wavy Fog sur le site de la NASA">Voir l'image PIA04641: Crater with Wavy Fog sur le site de la NASA.</a></div>
PIA04641: Crater with Wavy Fog
<h1>PIA04650: Small Volcano</h1><div class="PIA04650" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-425, 18 July 2003<p>This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image, acquired 13 July 2003, shows a small, dust-covered volcano on the plains east of Pavonis Mons. The floor of the caldera--the elliptical depression at the summit of the volcano--has a few windblown ripples on it. The ripples and thick dust mantle, together with the small impact craters on its surface, indicate that the volcano erupted some time ago. There has been no activity at this volcano in geologically recent times. This image covers an area 3 km wide by 6.8 km (1.9 mi by 4.2 mi); the aspect ratio is 1 across by 1.5 down. The volcano is located near 1.6°S, 105.7°W; sunlight illuminates the scene from the left.<p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04650" onclick="window.open(this.href); return false;" title="Voir l'image PIA04650: Small Volcano sur le site de la NASA">Voir l'image PIA04650: Small Volcano sur le site de la NASA.</a></div>
PIA04650: Small Volcano
<h1>PIA04653: Spiders from Mars?</h1><div class="PIA04653" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-426, 19 July 2003<p>No, this is not a picture of a giant, martian spider web. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of polygonal features on the floor of a northern hemisphere impact crater near 65.6°N, 327.7°W. The picture was acquired during spring, after the seasonal carbon dioxide frost cap had largely migrated through the region. At the time the picture was taken, remnants of seasonal frost remained on the crater rim and on the edges of the troughs that bound each of the polygons. Frost often provides a helpful hint as to where polygons and patterned ground occur. The polygons, if they were on Earth, would indicate the presence of freeze-thaw cycles in ground ice. Although uncertain, the same might be true of Mars. Sunlight illuminates the scene from the lower left.<p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04653" onclick="window.open(this.href); return false;" title="Voir l'image PIA04653: Spiders from Mars? sur le site de la NASA">Voir l'image PIA04653: Spiders from Mars? sur le site de la NASA.</a></div>
PIA04653: Spiders from Mars?
<h1>PIA04654: North Mid-latitude Crater</h1><div class="PIA04654" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-427, 20 July 2003<p />Craters in the middle latitudes of Mars often have strangely-textured floors. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of a crater near 40.2°N, 184.5°W provides an example. The original crater has been somewhat eroded and much of its interior has been filled with sediment since it formed. The origin of the strange texture is unknown; speculations about most mid-latitude textures tend to focus on the idea that, somehow, subliming ground ice may have been involved. The texture on the floor of the crater is similar to, but not quite the same as, the texture on the nearby surfaces to the north and south of the crater. This picture covers an area 1.4 km (0.9 mi) wide. Sunlight illuminates the scene from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04654" onclick="window.open(this.href); return false;" title="Voir l'image PIA04654: North Mid-latitude Crater sur le site de la NASA">Voir l'image PIA04654: North Mid-latitude Crater sur le site de la NASA.</a></div>
PIA04654: North Mid-latitude Crater
<h1>PIA04655: Polygons in Martian Frost</h1><div class="PIA04655" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-428, 21 July 2003<p />This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a polygonal pattern developed in seasonal carbon dioxide frost in the martian southern hemisphere. The frost accumulated during the recent southern winter; it is now spring, and the carbon dioxide frost is subliming away. This image is located near 80.4°S, 200.2°W; it is illuminated by sunlight from the upper left, and covers an area 3 km (1.9 mi) across.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04655" onclick="window.open(this.href); return false;" title="Voir l'image PIA04655: Polygons in Martian Frost sur le site de la NASA">Voir l'image PIA04655: Polygons in Martian Frost sur le site de la NASA.</a></div>
PIA04655: Polygons in Martian Frost
<h1>PIA04656: Stair-stepped Mound</h1><div class="PIA04656" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-429, 22 July 2003<p />This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a stair-stepped mound of sedimentary rock (right of center) on the floor of a large impact crater in western Arabia Terra near 11.0°N, 4.4°W. Sedimentary rock outcrops are common in the craters of this region. The repeated thickness and uniformity of the layers that make up this mound suggest that their depositional environment was one in which cyclic or episodic events occurred over some period of time. The sediments might have been deposited in a lake, or they may have settled directly out of the atmosphere. Most of the layered material was later eroded away, leaving this circular mound and the other nearby mesas and knobs. The image is illuminated by sunlight from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04656" onclick="window.open(this.href); return false;" title="Voir l'image PIA04656: Stair-stepped Mound sur le site de la NASA">Voir l'image PIA04656: Stair-stepped Mound sur le site de la NASA.</a></div>
PIA04656: Stair-stepped Mound
<h1>PIA04657: Clouds Near Icaria Planum</h1><div class="PIA04657" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-430, 23 July 2003<p />Like Earth, the martian atmosphere has clouds. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows small, puffy, water ice clouds over a cratered terrain near Icaria Planum. Illuminated by sunlight from the upper left, these small clouds cast shadows on the ground toward the lower right. This center of this image is near 31°S, 113°W. The picture was taken using MOC's blue wide angle camera.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04657" onclick="window.open(this.href); return false;" title="Voir l'image PIA04657: Clouds Near Icaria Planum sur le site de la NASA">Voir l'image PIA04657: Clouds Near Icaria Planum sur le site de la NASA.</a></div>
PIA04657: Clouds Near Icaria Planum
<h1>PIA04658: Layers in Crater Cluster</h1><div class="PIA04658" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-431, 24 July 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cluster of old, small impact craters near 36.3°N, 281.9°W. The group of craters was probably formed by secondary impacts following a much larger impact that occurred some distance away; the material that created these craters would have been the ejecta from the larger crater, rather than meteoroids from outer space. The craters cluster is considered to be relatively old because none of the craters have ejecta blankets any more, and each was filled, or partially filled, with layered material that was later eroded to form the terraced mounds found in their floors. This picture is illuminated from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04658" onclick="window.open(this.href); return false;" title="Voir l'image PIA04658: Layers in Crater Cluster sur le site de la NASA">Voir l'image PIA04658: Layers in Crater Cluster sur le site de la NASA.</a></div>
PIA04658: Layers in Crater Cluster
<h1>PIA04660: Fortune Cookie Sand Dunes</h1><div class="PIA04660" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-432, 25 July 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of small barchan sand dunes in the north polar region near 71.7°N, 51.3°W. Some of them are shaped like fortune cookies. The message these dunes provide: winds blow through this region from the lower right toward the upper left. The steep slip face slopes of these dunes, which point toward the upper left, indicate the wind direction. The scene is illuminated by sunlight from the upper right. The image is 3 km (1.9 mi) wide.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04660" onclick="window.open(this.href); return false;" title="Voir l'image PIA04660: Fortune Cookie Sand Dunes sur le site de la NASA">Voir l'image PIA04660: Fortune Cookie Sand Dunes sur le site de la NASA.</a></div>
PIA04660: Fortune Cookie Sand Dunes
<h1>PIA04662: Outcrop In Juventae Chasma</h1><div class="PIA04662" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-433, 26 July 2003<p />Light-toned sedimentary rock outcrops are common on the floors of the chasms associated with the Valles Marineris system and neighboring outflow channels. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an outcrop of sedimentary rock in Juventae Chasma near 4.1°S, 62.0°W. The scene is illuminated by sunlight from the left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04662" onclick="window.open(this.href); return false;" title="Voir l'image PIA04662: Outcrop In Juventae Chasma sur le site de la NASA">Voir l'image PIA04662: Outcrop In Juventae Chasma sur le site de la NASA.</a></div>
PIA04662: Outcrop In Juventae Chasma
<h1>PIA04663: Defrosting Sand Dunes</h1><div class="PIA04663" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-434, 27 July 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows retreating patches of frost on a field of large, dark sand dunes in the Noachis region of Mars. Large, windblown ripples of coarse sediment are also seen on some of the dunes. This dune field is located in a crater at 47.5°S, 326.3°W. The scene is illuminated by sunlight from the upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04663" onclick="window.open(this.href); return false;" title="Voir l'image PIA04663: Defrosting Sand Dunes sur le site de la NASA">Voir l'image PIA04663: Defrosting Sand Dunes sur le site de la NASA.</a></div>
PIA04663: Defrosting Sand Dunes
<h1>PIA04664: Textured Memnonia Plain</h1><div class="PIA04664" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-435, 28 July 2003<p />One of the goals of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Picture of the Day collection is to provide a sense of the great diversity of terrain, surfaces, patterns, and textures of the martian surface, as viewed by the MOC high resolution (narrow angle) camera. This image shows an intercrater plain in the Memnonia region that has been severely eroded by wind to form sharp ridges known as yardangs. This terrain would be very difficult to walk, or drive a rover, across. The picture is located near 11.8°S, 157.2°W. The scene is illuminated by sunlight from the left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04664" onclick="window.open(this.href); return false;" title="Voir l'image PIA04664: Textured Memnonia Plain sur le site de la NASA">Voir l'image PIA04664: Textured Memnonia Plain sur le site de la NASA.</a></div>
PIA04664: Textured Memnonia Plain
<h1>PIA04665: Cliff in Terby Crater</h1><div class="PIA04665" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-436, 29 July 2003<p />Terby Crater was once filled with layered, sedimentary rock. Over time, these materials have been eroded to form a dazzling array of cliffs and layered outcrops. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a layered cliff facing toward the northwest (toward upper left). Dark debris has slid down the west-facing slopes of the cliff. A visitor to Terby Crater would be greeted by vistas reminiscent of some of the national parks in the southwestern United States. This March 2003 picture is located near 27.7°S, 285.5°W; it is illuminated by sunlight from the upper left. The picture covers an area 3 km (1.9 mi) across.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04665" onclick="window.open(this.href); return false;" title="Voir l'image PIA04665: Cliff in Terby Crater sur le site de la NASA">Voir l'image PIA04665: Cliff in Terby Crater sur le site de la NASA.</a></div>
PIA04665: Cliff in Terby Crater
<h1>PIA04669: Olympus Mons Lava Flows</h1><div class="PIA04669" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-437, 30 July 2003<p />Olympus Mons is the largest volcano on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the lava flows on the middle south flank of the giant volcano. Illuminated from the lower right, this picture is located near 16.4°N, 135.5°W.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04669" onclick="window.open(this.href); return false;" title="Voir l'image PIA04669: Olympus Mons Lava Flows sur le site de la NASA">Voir l'image PIA04669: Olympus Mons Lava Flows sur le site de la NASA.</a></div>
PIA04669: Olympus Mons Lava Flows
<h1>PIA04670: South Polar Scarps</h1><div class="PIA04670" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-438, 31 July 2003<p />The terrain of the south polar residual ice cap, made up mostly of frozen carbon dioxide, has come to be known by many as "swiss cheese terrain," because many areas of the cap resemble slices of swiss cheese. However, not all of the south polar cap looks like a tasty lunch food. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a series of curving scarps formed by erosion and sublimation of carbon dioxide from the south polar cap. This area is located near 86.3°S, 51.2°W. The image is illuminated by sunlight from the upper left; the area is about 1.5 km (0.9 mi) wide.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04670" onclick="window.open(this.href); return false;" title="Voir l'image PIA04670: South Polar Scarps sur le site de la NASA">Voir l'image PIA04670: South Polar Scarps sur le site de la NASA.</a></div>
PIA04670: South Polar Scarps
<h1>PIA04672: Gale Sedimentary Rocks</h1><div class="PIA04672" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-439, 1 August 2003<p />Gale Crater, located in the Aeolis region near 5.5°S, 222°W, contains a mound of layered sedimentary rock that stands higher than the rim of the crater. This giant mound suggests that the entire crater was not only once filled with sediment, it was also buried beneath sediment. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the eroded remains of the sedimentary rock that once filled Gale Crater. The layers form terraces; wind has eroded the material to form the tapered, pointed yardang ridges seen here. The small circular feature in the lower right quarter of the picture is a mesa that was once a small meteor impact crater that was filled, buried, then exhumed from within the sedimentary rock layers exposed here. This image is illuminated from the left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04672" onclick="window.open(this.href); return false;" title="Voir l'image PIA04672: Gale Sedimentary Rocks sur le site de la NASA">Voir l'image PIA04672: Gale Sedimentary Rocks sur le site de la NASA.</a></div>
PIA04672: Gale Sedimentary Rocks
<h1>PIA04674: Warrego Valles</h1><div class="PIA04674" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-440, 2 August 2003<p />Warrego Valles is a suite of branching valleys located in the martian southern hemisphere near 43°S, 92°W. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the valleys of this system. They are old and have been partially filled with material that today forms an eroded, rugged texture. Prior to the MGS mission, it had been hoped that MOC would show evidence as to how valleys such as those in the Warrego system formed, but many of the valleys turned out to have been modified by later processes that obscure the original geologic features related to their origin. This image is illuminated from the upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04674" onclick="window.open(this.href); return false;" title="Voir l'image PIA04674: Warrego Valles sur le site de la NASA">Voir l'image PIA04674: Warrego Valles sur le site de la NASA.</a></div>
PIA04674: Warrego Valles
<h1>PIA04675: Labou Vallis</h1><div class="PIA04675" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-441, 3 August 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the wind-eroded surfaces of the Labou Vallis system. The original valley walls and floor were covered with a material that was later eroded by wind to form the sharp, rough textured terrain seen here. Avalanches of dust formed dark streaks on some slopes. This picture is located near 8.5°S, 154.7°W. It is illuminated by sunlight from the left. <p />Other versions of this picture:<a href="M07-03611.gif">Full-resolution GIF (~3.7 m/pixel) of entire original image, M07-03611</a><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04675" onclick="window.open(this.href); return false;" title="Voir l'image PIA04675: Labou Vallis sur le site de la NASA">Voir l'image PIA04675: Labou Vallis sur le site de la NASA.</a></div>
PIA04675: Labou Vallis
<h1>PIA04676: Marte Vallis Platy Flows</h1><div class="PIA04676" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-442, 4 August 2003<p />The Marte Vallis system, located east of Cerberus and west of Amazonis Planitia, is known for its array of broken, platy flow features. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a close-up view of some of these plates; they appear to be like puzzle pieces that have been broken apart and moved away from each other. The Mars science community has been discussing these features for the past several years--either the flows in Marte Vallis are lava flows, or mud flows. In either case, the material was very fluid and had a thin crust on its surface. As the material continued to flow through the valley system, the crust broke up into smaller plates that were then rafted some distance down the valley. This picture is located near 6.9°N, 182.8°W. It is illuminated by sunlight from the left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04676" onclick="window.open(this.href); return false;" title="Voir l'image PIA04676: Marte Vallis Platy Flows sur le site de la NASA">Voir l'image PIA04676: Marte Vallis Platy Flows sur le site de la NASA.</a></div>
PIA04676: Marte Vallis Platy Flows
<h1>PIA04677: Aeolis Yardangs</h1><div class="PIA04677" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-443, 5 August 2003<p />Yardangs are ridges formed by wind erosion. The classic, "textbook" examples of yardangs are those that appear to be like the inverted hull of a boat. They most commonly form in sedimentary rock or volcanic ash deposits that contain some proportion of sand-sized grains. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows yardangs in the Aeolis region of Mars. Their tapered ends point toward the upper left, indicating the dominant winds responsible for their erosion came from the lower right. This picture is located near 1.0°N, 214.4°W. It is illuminated by sunlight from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04677" onclick="window.open(this.href); return false;" title="Voir l'image PIA04677: Aeolis Yardangs sur le site de la NASA">Voir l'image PIA04677: Aeolis Yardangs sur le site de la NASA.</a></div>
PIA04677: Aeolis Yardangs
<h1>PIA04678: Pedestal Crater and Yardangs</h1><div class="PIA04678" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-444, 6 August 2003<p />This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact crater that has been modified by wind erosion. Two things happened after the crater formed. First, the upper few meters of surface material into which the meteor impacted was later eroded away by wind. The crater ejecta formed a protective armor that kept the material under the ejecta from been blown away. This caused the crater and ejecta to appear as if standing upon a raised platform--a feature that Mars geologists call a pedestal crater. Next, the pedestal crater was buried beneath several meters of new sediment, and then this material was eroded away by wind to form the array of sharp ridges that run across the pedestal crater's surface. These small ridges are known as yardangs. This picture is illuminated by sunlight from the upper left; it is located in west Daedalia Planum near 14.6°S, 131.9°W.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04678" onclick="window.open(this.href); return false;" title="Voir l'image PIA04678: Pedestal Crater and Yardangs sur le site de la NASA">Voir l'image PIA04678: Pedestal Crater and Yardangs sur le site de la NASA.</a></div>
PIA04678: Pedestal Crater and Yardangs
<h1>PIA04679: Layers in Tithonium Chasma</h1><div class="PIA04679" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-445, 7 August 2003<p />Tithonium Chasma is one of the troughs of the vast Valles Marineris canyon system. Within many of these troughs are outcrops of light-toned, layered, sedimentary rock. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded sedimentary rock exposures overlain by the remnants of a smoother-surfaced, dark material. The dark feature is a younger sedimentary deposit made of a different material than the light-toned sediments; it covered the lighter rocks after they were eroded to their present form. This area is located near 5.0°S, 89.8°W. Sunlight illuminates the scene from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04679" onclick="window.open(this.href); return false;" title="Voir l'image PIA04679: Layers in Tithonium Chasma sur le site de la NASA">Voir l'image PIA04679: Layers in Tithonium Chasma sur le site de la NASA.</a></div>
PIA04679: Layers in Tithonium Chasma
<h1>PIA04680: Northeast Hellas Landscape</h1><div class="PIA04680" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-446, 8 August 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of pitted terrain northeast of Hellas Basin shows light-toned outcrops of layered, sedimentary rock, and a valley floor covered by large, dark ripples or small dunes. Similar light-toned sedimentary materials are found throughout the region immediately northeast of Hellas, and in the crater, Terby. The area shown is 3 km (1.9 mi) wide and located near 27.5°S, 281.7°W. Sunlight illuminates the scene from the upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04680" onclick="window.open(this.href); return false;" title="Voir l'image PIA04680: Northeast Hellas Landscape sur le site de la NASA">Voir l'image PIA04680: Northeast Hellas Landscape sur le site de la NASA.</a></div>
PIA04680: Northeast Hellas Landscape
<h1>PIA04681: Large, Windblown Ripples</h1><div class="PIA04681" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-447, 9 August 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the plethora of large, windblown ripples (or small dunes) among wind-sculpted sedimentary rocks in eastern Candor Chasma. Candor Chasma is one of the troughs of the Valles Marineris, a system of chasms that would stretch all the way across North America if it were on Earth. This picture is located near 7.9°S, 64.9°W. Sunlight illuminates the scene from the left/upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04681" onclick="window.open(this.href); return false;" title="Voir l'image PIA04681: Large, Windblown Ripples sur le site de la NASA">Voir l'image PIA04681: Large, Windblown Ripples sur le site de la NASA.</a></div>
PIA04681: Large, Windblown Ripples
<h1>PIA04682: Scamander Vallis</h1><div class="PIA04682" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-448, 10 August 2003<p />The heavily cratered terrains of Mars bear the scars of many, ancient valley systems and networks. When these were first seen in images from Mariner 9 more than 30 years ago, most investigators working on the topic concluded that the valleys must have formed by running water. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a somewhat meandered portion of Scamander Vallis, located in central Arabia Terra near 16.9°N, 331.5°W. The valley today is quite dry and the entire area--valley, craters, and surrounding terrain--are covered by an almost uniform blanket of dust. Dark streaks on the slopes are formed by small avalanches of dust. Sunlight illuminates the scene from the right.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04682" onclick="window.open(this.href); return false;" title="Voir l'image PIA04682: Scamander Vallis sur le site de la NASA">Voir l'image PIA04682: Scamander Vallis sur le site de la NASA.</a></div>
PIA04682: Scamander Vallis
<h1>PIA04683: Bouldery Surface</h1><div class="PIA04683" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-449, 11 August 2003<p />This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution image shows part of the boulder-strewn surface of an ejecta deposit from a meteor impact crater in Noachis Terra at 49.7°S, 341.6°W. The impact process ejects bouldery debris from the crater and deposits it all around the outside of the crater. Sunlight illuminates the scene from the upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04683" onclick="window.open(this.href); return false;" title="Voir l'image PIA04683: Bouldery Surface sur le site de la NASA">Voir l'image PIA04683: Bouldery Surface sur le site de la NASA.</a></div>
PIA04683: Bouldery Surface
<h1>PIA04684: Peridier Crater</h1><div class="PIA04684" lang="en" style="width:540px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-450, 12 August 2003<p />The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red instrument captured this autumn view of Peridier Crater on August 6, 2003. The crater is about 100 km (62 mi.) in diameter and located at 25.7°N, 276.2°W. It was named for French astronomer Julien Peridier (1882-1967). In this Mercator map-projected view, north is up and east is to the right. The dark feature on the southwest floor of the crater is known from high resolution MOC images to be a field of windblown dunes. Finer, dark-toned sediment has been blown out of the dune field and settled on the crater rim and just outside the crater to the southwest. Sunlight illuminates the scene from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04684" onclick="window.open(this.href); return false;" title="Voir l'image PIA04684: Peridier Crater sur le site de la NASA">Voir l'image PIA04684: Peridier Crater sur le site de la NASA.</a></div>
PIA04684: Peridier Crater
<h1>PIA04685: South Polar Mesas</h1><div class="PIA04685" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MGS MOC Release No. MOC2-451, 13 August 2003<p />This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of small mesas with sharp, arcuate edges located on the south polar residual cap of Mars. These mesas, each about 2 meters (6-7 feet) high, are all remnants of a single layer or grouping of layers of frozen carbon dioxide. Sublimation of the carbon dioxide has eroded the layer(s) from these flat-topped mesas. This scene is located near 86.6°S, 105.4°W and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA04685" onclick="window.open(this.href); return false;" title="Voir l'image PIA04685: South Polar Mesas sur le site de la NASA">Voir l'image PIA04685: South Polar Mesas sur le site de la NASA.</a></div>
PIA04685: South Polar Mesas

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