Cette galrie comprend des photos provenant des observations réalisées par le télescope spatial Hubble, de la mission MSG Mars Global Surveyor, quelques photos de Mariner, de Mars Express et des phtos diverses.

Galerie de photos de la planète Mars

<h1>PIA02336: The Mysterious Martian Mountains of Mitchel</h1><div class="PIA02336" lang="en" style="width:550px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image covers an 800 by 300 km (500 by 190 mi) area located deep within the boundary of the seasonal south polar frost cap of Mars. Centered at 70°S, 320°W, this view--taken in early spring when sunlight has just begun to shine on the region for the first time in many months--includes a bright region (diagonal from center-left to lower right) known for nearly two centuries as the "Mountains of Mitchel." This feature was named for Ormsby McKnight Mitchel (1809-1862), an astronomer at the University of Cincinnati, Ohio, who discovered it while observing Mars through a telescope in 1846. Mitchel noticed that this area is typically "left behind" as a bright peninsula when the rest of the polarcap recedes past this area later in the spring.<p>Mitchel deduced that this area might be mountainous because it seemed analogous to the snow that is left on Earth's mountain ranges in late spring and into summer. Snow can remain on high peaks because the air temperature decreases with elevation (or altitude). MGS Mars Orbiter Laser Altimeter (MOLA) observations of this region show the bright "Mountains of Mitchel" to be a somewhat elevated region of rough, heavily cratered southern highlands. However, the "Mountains of Mitchel" do not appear to be mountains-there are other areas nearby at similar elevation that do not retain frost well into southern spring. Part of the Mountains of Mitchel feature includes a prominent, south-facing scarp (at center-left) that would tend to retain frost longer in the spring because it is somewhat protected from sunlight (which comes from the north). The persistence of frost on the Mountains of Mitchel remains mysterious, but new observations from the MGS MOC are helping to unravel the story. Thus far, it seems that the frost here--for whatever reason--tends to be brighter than frost in most other places within the polar cap. This brighter frost reflects sunlight and thus sublimes more slowly than adjacent, darker frost surfaces.<p>This color picture was compiled from MOC red and blue wide angle images. North is up and sunlight illuminates the scene from the upper left. The surface does not appear to be white--as might be expected for frost--because of dust both on the surface and in the atmosphere, as well dark sand that was being exposed from beneath the retreating frost at the time that the picture was taken.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02336" onclick="window.open(this.href); return false;" title="Voir l'image PIA02336: The Mysterious Martian Mountains of Mitchel sur le site de la NASA">Voir l'image PIA02336: The Mysterious Martian Mountains of Mitchel sur le site de la NASA.</a></div>
PIA02336: The Mysterious Martian Mountains of Mitchel
<h1>PIA02337: Wide Angle View of Arsia Mons Volcano</h1><div class="PIA02337" lang="en" style="width:742px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120° west longitude and 9° south latitude. Illumination is from the left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02337" onclick="window.open(this.href); return false;" title="Voir l'image PIA02337: Wide Angle View of Arsia Mons Volcano sur le site de la NASA">Voir l'image PIA02337: Wide Angle View of Arsia Mons Volcano sur le site de la NASA.</a></div>
PIA02337: Wide Angle View of Arsia Mons Volcano
<h1>PIA02342: MOC Views of Martian Solar Eclipses</h1><div class="PIA02342" lang="en" style="width:705px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_187_fullres.gif"></a><br><br><p>The shadow of the martian moon, Phobos, has been captured in many recent wide angle camera views of the red planet obtained by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). Designed to monitor changes in weather and surface conditions, the wide angle cameras are also proving to be a good way to spot the frequent solar eclipses caused by the passage of Phobos between Mars and the Sun.<p>The first figure (above), shows wide angle red (left), blue (middle), and color composite (right) views of the shadow of Phobos (elliptical feature at center of each frame) as it was cast upon western Xanthe Terra on August 26, 1999, at about 2 p.m.local time on Mars. The image covers an area about 250 kilometers (155 miles) across and is illuminated from the left. The meandering Nanedi Valles is visible in the lower right corner of the scene. Note the dark spots on three crater floors--these appear dark in the red camera image (left) but are barely distinguished in the blue image (middle), while the shadow is dark in both images. The spots on the crater floors are probably small fields of dark sand dunes.<p>The second figure shows three samples of MOC's global image swaths, each in this case with a shadow of Phobos visible (arrow). The first scene (left) was taken on September 1, 1999, and shows the shadow of Phobos cast upon southern Elysium Planitia. The large crater with dark markings on its floor at the lower right corner is Herschel Basin. The second scene shows the shadow of Phobos cast upon northern Lunae Planum on September 8, 1999. Kasei Valles dominates the upper right and the deep chasms of Valles Marineris dominate the lower third of the September 8 image. The picture on the right shows the shadow of Phobos near the giant volcano, Olympus Mons (upper left), on September 25, 1999. Three other major volcanoes are visible from lower-center (Arsia Mons) and right-center (Pavonis Mons) to upper-middle-right (Ascraeus Mons).<p>Phobos and the smaller, more distant satellite, Deimos, were discovered in 1877 by Asaph Hall, an astronomer at the United States Naval Observatory in Washington, D.C. Hall had been hunting for martian satellites for some time, and was about to abandon the search when he was encouraged by his wife to continue. In honor of her role, the largest crater on Phobos was named Stickney, her maiden name. Phobos is a tiny, potato-shaped world that is only about 13 km by 11 km by 9 km (8 mi by 7 mi by 6 mi) in size.<p>In 1912 Edgar Rice Burroughs published a story entitled "Under the Moons of Mars" (printed in book form in 1917 as A Princess of Mars) in which he referred to the "hurtling moons of Barsoom" (Barsoom being the "native" word for Mars in the fictional account). Burroughs was inspired by the fact that Phobos, having an orbital period of slightly less than 8 hours, would appear from Mars to rise in the west and set in the east only five and a half hours later. (Despite Burroughs' phrase, the outer moon, Deimos, can hardly be said to "hurtle" -- it takes nearly 60 hours to cross the sky from east to west, rising on one day and not setting again for over two more.)<p>If you could stand on Mars and watch Phobos passing overhead, you would notice that this moon appears to be only about half the size of what Earth's Moon looks like when viewed from the ground. In addition, the Sun would seem to have shrunk to about 2/3 (or nearly 1/2) of its size as seen from Earth. Martian eclipses are therefore dark but not as spectacular as total solar eclipses on Earth can be. In compensation, the martian eclipses are thousands of times more common, occurring a few times a day somewhere on Mars whenever Phobos passes over the planet's sunlit side. Due to the changing geometry of the MGS orbit relative to that of Phobos, the shadow is actually seen in MOC global map images (like in the second figure above) about a dozen times a month.<p>The shadow of Phobos was seen during the Viking missions in the late 1970s, and in fact one day the shadow was observed to pass right over the Viking 1 lander. The surface of Phobos itself was first imaged by Mariner 9 in 1971, and global coverage was obtained by the Viking orbiters in 1976-80. Phobos was the target of the ill-fated Phobos 1 and Phobos 2 spacecraft, launched by the Soviet Union in 1988. Phobos 2 actually reached Mars in 1989 and obtained a few pictures of the satellite--it also captured the shadow of Phobos cast upon the martian surface using its thermal infrared imager, Termoskan. More recently, the MGS MOC observed the tiny moon four times in August and September 1998.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02342" onclick="window.open(this.href); return false;" title="Voir l'image PIA02342: MOC Views of Martian Solar Eclipses sur le site de la NASA">Voir l'image PIA02342: MOC Views of Martian Solar Eclipses sur le site de la NASA.</a></div>
PIA02342: MOC Views of Martian Solar Eclipses
<h1>PIA02348: Latest Color View of Polar Landing Site</h1><div class="PIA02348" lang="en" style="width:378px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>On December 3rd, Mars Polar Lander and the Deep Space 2 Microprobes (Scott and Amundsen) will land somewhere in the picture shown here. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle camera view of the polar landing ellipse was taken on November 28, 1999. Dark patches within the ellipse are sand and small fields of windblown sand dunes. The bright patches toward the top of the image are frost. It is late spring in this portion of the martian south polar region, and much of the winter frost has finally sublimed away. The ellipse center is located at 76°S 195°W. In this view, nor this toward the bottom and sunlight illuminates the scene from the lower right. The image covers an area approximately 105 km (65 miles) wide by 335 km (210 miles) long.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02348" onclick="window.open(this.href); return false;" title="Voir l'image PIA02348: Latest Color View of Polar Landing Site sur le site de la NASA">Voir l'image PIA02348: Latest Color View of Polar Landing Site sur le site de la NASA.</a></div>
PIA02348: Latest Color View of Polar Landing Site
<h1>PIA02381: Cydonia: Wide Angle Color Image</h1><div class="PIA02381" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_222b.jpg"></a><br><p>Although the resolution of the MOC wide angle cameras is too low to tell much about the geomorphology of the Cydonia region, the images from the red and blue wide angle cameras provide us with two types of information that is of interest in their own right: color and stereoscopic data. Above are a color view and a stereoscopic anaglyph rendition of Geodesy Campaign images acquired by MGS MOC in May 1999. To view the stereo image, you need red/blue "3-D" glasses.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02381" onclick="window.open(this.href); return false;" title="Voir l'image PIA02381: Cydonia: Wide Angle Color Image sur le site de la NASA">Voir l'image PIA02381: Cydonia: Wide Angle Color Image sur le site de la NASA.</a></div>
PIA02381: Cydonia: Wide Angle Color Image
<h1>PIA02393: South Polar Cap, Summer 2000</h1><div class="PIA02393" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This is the south polar cap of Mars as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000. In winter and early spring, this entire scene would be covered by frost. In summer, the cap shrinks to its minimum size, as shown here. Even though it is summer, observations made by the Viking orbiters in the 1970s showed that the south polar cap remains cold enough that the polar frost (seen here as white) consists of carbon dioxide. Carbon dioxide freezes at temperatures around -125° C (-193° F). Mid-summer afternoon sunlight illuminates this scene from the upper left from about 11.2° above the horizon. Soon the cap will experience sunsets; by June 2000, this pole will be in autumn, and the area covered by frost will begin to grow. Winter will return to the south polar region in December 2000. The polar cap from left to right is about 420 km (260 mi) across.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02393" onclick="window.open(this.href); return false;" title="Voir l'image PIA02393: South Polar Cap, Summer 2000 sur le site de la NASA">Voir l'image PIA02393: South Polar Cap, Summer 2000 sur le site de la NASA.</a></div>
PIA02393: South Polar Cap, Summer 2000
<h1>PIA02394: The Frosty Rims of Lomonosov Crater in Winter</h1><div class="PIA02394" lang="en" style="width:528px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>It is still winter in the northern hemisphere of Mars. On April 20, 2000, the Mars Orbiter Camera (MOC) onboard Mars Global Surveyor (MGS) captured this view of a chilly Lomonosov Crater. The rims of the crater appear white because they are covered with wintertime frost. A dark patch just right of center on the crater floor is a sand dune field. Both low-lying ground fogs(fuzzy, patchy areas around the lower perimeter of the crater) and higher cloud layers (fuzzy white arcs seen within the crater and towards the upper right) obscure much of the surface. The sun, only 12° above the horizon, bathes the scene in a reddish-brown hue. Lomonosov Crater is about 150 km (93 mi) across and located on the martian northern plains at 64.8° N, 8.8° W. The crater is named for the 18th Century Russian chemist, Mikhail V. Lomonosov (1741-1765). Spring will arrive in the martian northern hemisphere around June 1, 2000, and summer will come in December 2000. Sunlight illuminates this scene from the lower left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02394" onclick="window.open(this.href); return false;" title="Voir l'image PIA02394: The Frosty Rims of Lomonosov Crater in Winter sur le site de la NASA">Voir l'image PIA02394: The Frosty Rims of Lomonosov Crater in Winter sur le site de la NASA.</a></div>
PIA02394: The Frosty Rims of Lomonosov Crater in Winter
<h1>PIA02395: A Valley in the Libya Montes</h1><div class="PIA02395" lang="en" style="width:137px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_227d.jpg"></a><br><b>(A)</b><a href="/figures/moc2_227b.jpg"></a><br><b>(B)</b><a href="/figures/moc2_227c.gif"></a><br><b>(C)</b><p>This Mars Global Surveyor Mars Orbiter Camera narrow angle image (top) shows an intermountain valley floor in the Libya Montes region of Mars. Its regional setting is seen in the wide angle color mosaic (Figure A). The Libya Montes were formed by the giant impact that created the ancient Isidis basin. The Libya Mountains and valleys--like the one shown here--were subsequently modified and eroded by other processes, including wind, impact cratering, and flow of liquid water to make the small valley that runs across the middle of the scene. Until the mission was canceled, the Libya Montes region was among the top two candidates for the Mars Surveyor 2001 Lander. This image, illuminated by sunlight from the left, covers an area 3 kilometers (1.9 miles) wide and 19 kilometers (11.8 miles) long. The scene is located near 1.5°N, 278.4°W and was acquired on June 27, 1999. The high resolution color view (top) was created by combining the colors derived from Mars Orbiter Camera Wide Angle views of the region obtained in May 1999 (Figures A and B) with the high resolution view obtained in June 1999 (Figure C).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02395" onclick="window.open(this.href); return false;" title="Voir l'image PIA02395: A Valley in the Libya Montes sur le site de la NASA">Voir l'image PIA02395: A Valley in the Libya Montes sur le site de la NASA.</a></div>
PIA02395: A Valley in the Libya Montes
<h1>PIA02396: A Regional View of the Libya Montes</h1><div class="PIA02396" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_228b.jpg"></a><p>The Libya Montes are a ring of mountains up-lifted by the giant impact that created the Isidis basin to the north. During 1999, this region became one of the top two that were being considered for the now-canceled Mars Surveyor 2001 Lander. The Isidis basin is very, very ancient. Thus, the mountains that form its rims would contain some of the oldest rocks available at the Martian surface, and a landing in this region might potentially provide information about conditions on early Mars. In May 1999, the wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera system were used in what was called the "Geodesy Campaign" to obtain nearly global maps of the planet in color and in stereo at resolutions of 240 m/pixel (787 ft/pixel) for the red camera and 480 m/pixel (1575 ft/pixel) for the blue. Shown here are color and stereo views constructed from mosaics of the Geodesy Campaign images for the Libya Montes region of Mars. After they formed by giant impact, the Libya Mountains and valleys were subsequently modified and eroded by other processes, including wind, impact cratering, and flow of liquid water to make the many small valleys that can be seen running northward in the scene. The pictures shown here cover nearly 122,000 square kilometers (47,000 square miles) between latitudes 0.1°N and 4.0°N, longitudes 271.5°W and 279.9°W. The mosaics are about 518 km (322 mi) wide by 235 km (146 mi) high. Red-blue "3-D" glasses are needed to view the stereo image.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02396" onclick="window.open(this.href); return false;" title="Voir l'image PIA02396: A Regional View of the Libya Montes sur le site de la NASA">Voir l'image PIA02396: A Regional View of the Libya Montes sur le site de la NASA.</a></div>
PIA02396: A Regional View of the Libya Montes
<h1>PIA02612: Mars at Ls 12°: Elysium/Mare Cimmerium</h1><div class="PIA02612" lang="en" style="width:640px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>28 February 2006<br />This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 12° during a previous Mars year. This month, Mars looks similar, as Ls 12° occurred in mid-February 2006. The picture shows the Elysium/Mare Cimmerium face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360° around the Sun in 1 Mars year. The year begins at Ls 0°, the start of northern spring and southern autumn.</p><p>Season: Northern Spring/Southern Autumn </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02612" onclick="window.open(this.href); return false;" title="Voir l'image PIA02612: Mars at Ls 12°: Elysium/Mare Cimmerium sur le site de la NASA">Voir l'image PIA02612: Mars at Ls 12°: Elysium/Mare Cimmerium sur le site de la NASA.</a></div>
PIA02612: Mars at Ls 12°: Elysium/Mare Cimmerium
<h1>PIA02653: Mars Daily Global Image from April 1999</h1><div class="PIA02653" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Twelve orbits a day provide the Mars Global Surveyor MOC wide angle cameras a global "snapshot" of weather patterns across the planet. Here, bluish-white water ice clouds hang above the Tharsis volcanoes. This computer generated image was created by wrapping the global map found at <a href="/catalog/PIA02066">PIA02066</a> onto a sphere. The center of this newly projected sphere is located at 15degrees North, 90 degrees West. This perspective rotates the south pole (which has no data coverage in the original map) away from our field of view.<p>Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02653" onclick="window.open(this.href); return false;" title="Voir l'image PIA02653: Mars Daily Global Image from April 1999 sur le site de la NASA">Voir l'image PIA02653: Mars Daily Global Image from April 1999 sur le site de la NASA.</a></div>
PIA02653: Mars Daily Global Image from April 1999
<h1>PIA02697: Mars at Ls 25°: Tharsis</h1><div class="PIA02697" lang="en" style="width:640px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>7 March 2006<br />This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 25° during a previous Mars year. This month, Mars looks similar, as Ls 25° occurs in mid-March 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360° around the Sun in 1 Mars year. The year begins at Ls 0°, the start of northern spring and southern autumn.</p><p>Season: Northern Spring/Southern Autumn </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02697" onclick="window.open(this.href); return false;" title="Voir l'image PIA02697: Mars at Ls 25°: Tharsis sur le site de la NASA">Voir l'image PIA02697: Mars at Ls 25°: Tharsis sur le site de la NASA.</a></div>
PIA02697: Mars at Ls 25°: Tharsis
<h1>PIA02800: The Martian North Polar Cap in Summer</h1><div class="PIA02800" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This is a wide angle view of the martian north polar cap as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in early northern summer. The picture was acquired on March 13, 1999, near the start of the Mapping Phase of the MGS mission. The light-toned surfaces are residual water ice that remains through the summer season. The nearly circular band of dark material surrounding the cap consists mainly of sand dunes formed and shaped by wind. The north polar cap is roughly 1100 kilometers (680 miles) across.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02800" onclick="window.open(this.href); return false;" title="Voir l'image PIA02800: The Martian North Polar Cap in Summer sur le site de la NASA">Voir l'image PIA02800: The Martian North Polar Cap in Summer sur le site de la NASA.</a></div>
PIA02800: The Martian North Polar Cap in Summer
<h1>PIA02810: Looking Out Across Dao, Niger, and Harmakhis Valles</h1><div class="PIA02810" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) opened its fourth year orbiting the red planet with this mid-autumn view of three major valley systems east of the Hellas plains. From left to right, the first major valley, Dao Vallis, runs diagonally from the upper left to just past the lower center of the image. Niger Vallis joins Dao Vallis just above the center of the frame. Harmakhis Vallis extends diagonally across the right half of the picture, toward the lower right. These valleys are believed by some to have been formed--at least in part--by large outbursts of liquid water some time far back in the martian past, though there is no way to know exactly how many hundreds of millions or billions of years ago this might have occurred. In each valley, water would have flowed toward the bottom of the image. Although their dimensions vary along their courses, the valleys are all roughly 1 km (0.6 miles) deep and range in width from about 40 km (25 miles) down to about 8 km (5 mi). Located around 40°S, 270°W, the picture covers an area approximately 800 km across and is illuminated by sunlight from the lower left. North is toward the left; the picture is a composite of red and blue wide angle images obtained by MOC on September 13, 2000.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02810" onclick="window.open(this.href); return false;" title="Voir l'image PIA02810: Looking Out Across Dao, Niger, and Harmakhis Valles sur le site de la NASA">Voir l'image PIA02810: Looking Out Across Dao, Niger, and Harmakhis Valles sur le site de la NASA.</a></div>
PIA02810: Looking Out Across Dao, Niger, and Harmakhis Valles
<h1>PIA02811: Frosted Southern Plains in Early Spring</h1><div class="PIA02811" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The Martian southern hemisphere was nearly 2 months into its spring season when this picture was taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on September 25, 1999. The scene covers a vast, frost-coated plain south of the Martian antarctic circle. The icy terrain in the image has an almost pastel-like character, owing to the mixture of reddish dust both on, in, and under the white frost. The frost--mostly frozen water at this time of year--is left over from winter, which ended August 2, 1999. One martian year is about 687 Earth days long, thus each of the planet's four seasons are nearly twice as long as seasons on Earth. The largest crater in the upper left is Lau Crater, named for the Danish astronomer, Hans E. Lau (1879-1918). The dark spot near the center of the image has no name, and its origin is unknown. The picture covers an area about 1,020 km (634 mi) across by approximately 1,240 km (771 mi) down. The center is located near 76°S, 97°W, and north is toward the upper right. Sunlight illuminates the scene from the upper left. This is a color composite of M07-04748 (red) and M07-04749 (blue) wide angle MOC images. To see what the raw MOC image data look like, visit the newest data releases (for Mission Subphases M07 - M12, covering September 1999 through February 2000) in the <a href="http://www.msss.com/moc_gallery/">MOC GALLERY</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02811" onclick="window.open(this.href); return false;" title="Voir l'image PIA02811: Frosted Southern Plains in Early Spring sur le site de la NASA">Voir l'image PIA02811: Frosted Southern Plains in Early Spring sur le site de la NASA.</a></div>
PIA02811: Frosted Southern Plains in Early Spring
<h1>PIA02812: Spring Thaw in Northwestern Planum Australe</h1><div class="PIA02812" lang="en" style="width:227px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Planum Australe--the Plains of the South. Patchy frost lingers late into Martian spring in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view from November 25, 1999. Spring would give way to summer in only 1 month, on December 25, 1999. The surfaces underneath the frost have different properties--some get warmer while others stay cold--thus causing frost to linger on colder surfaces and sublime away from warmer surfaces, leaving the dazzling, almost psychedelic pattern seen at the center of this image. Circular features in this view are old craters formed by meteor impact. The brightest patches within most of these circles are fields of sand dunes covered by frost. The center of this scene is near 78°S, 135°W; north is toward the upper right. Illumination is from the upper left. The image covers an area 110 km (68 mi) across by 590 km (367 mi) down. This is a color composite of MOC wide angle camera images M09-06029 (red) and M09-06030 (blue). To see what the raw MOC image data look like, visit the newest data releases (for Mission Subphases M07 - M12, covering September 1999 through February 2000) in the <a href="http://www.msss.com/moc_gallery/">MOC GALLERY</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02812" onclick="window.open(this.href); return false;" title="Voir l'image PIA02812: Spring Thaw in Northwestern Planum Australe sur le site de la NASA">Voir l'image PIA02812: Spring Thaw in Northwestern Planum Australe sur le site de la NASA.</a></div>
PIA02812: Spring Thaw in Northwestern Planum Australe
<h1>PIA02824: Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater</h1><div class="PIA02824" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_242b.gif"></a><br><br><p>Newton Crater is a large basin formed by an asteroid impact that probably occurred more than 3 billion years ago. It is approximately 287 kilometers (178 miles) across. The picture shown here (top) highlights the north wall of a specific, smaller crater located in the southwestern quarter of Newton Crater (above). The crater of interest was also formed by an impact; it is about 7 km (4.4 mi) across, which is about 7 times bigger than the famous Meteor Crater in northern Arizona in North America.<p>The north wall of the small crater has many narrow gullies eroded into it. These are hypothesized to have been formed by flowing water and debris flows. Debris transported with the water created lobed and finger-like deposits at the base of the crater wall where it intersects the floor (bottom center top image). Many of the finger-like deposits have small channels indicating that a liquid--most likely water--flowed in these areas. Hundreds of individual water and debris flow events might have occurred to create the scene shown here. Each outburst of water from higher upon the crater slopes would have constituted a competition between evaporation, freezing, and gravity.<p>The individual deposits at the ends of channels in this MOC image mosaic were used to get a rough estimate of the minimum amount of water that might be involved in each flow event. This is done first by assuming that the deposits are like debris flows on Earth. In a debris flow, no less than about 10% (and no more than 30%) of their volume is water. Second, the volume of an apron deposit is estimated by measuring the area covered in the MOC image and multiplying it by a conservative estimate of thickness, 2 meters (6.5 feet). For a flow containing only 10% water, these estimates conservatively suggest that about 2.5 million liters (660,000 gallons) of water are involved in each event; this is enough to fill about 7 community-sized swimming pools or enough to supply 20 people with their water needs for a year.<p>The MOC high resolution view is located near 41.1°S, 159.8°W and is a mosaic of three different pictures acquired between January and May 2000. The MOC scene is illuminated from the left; north is up. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right.<p><b>Note</b>: This is an updated color version of <a href="/catalog/PIA01039">PIA01039</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02824" onclick="window.open(this.href); return false;" title="Voir l'image PIA02824: Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater sur le site de la NASA">Voir l'image PIA02824: Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater sur le site de la NASA.</a></div>
PIA02824: Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater
<h1>PIA02833: The Frosted Craters of Northern Spring and Southern Autumn - Lomonosov Crater</h1><div class="PIA02833" lang="en" style="width:797px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see <a href="/catalog/PIA02394">"The Frosty Rims of Lomonosov Crater in Winter."</a><p>This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02833" onclick="window.open(this.href); return false;" title="Voir l'image PIA02833: The Frosted Craters of Northern Spring and Southern Autumn - Lomonosov Crater sur le site de la NASA">Voir l'image PIA02833: The Frosted Craters of Northern Spring and Southern Autumn - Lomonosov Crater sur le site de la NASA.</a></div>
PIA02833: The Frosted Craters of Northern Spring and Southern Autumn - Lomonosov Crater
<h1>PIA02834: The Frosted Craters of Northern Spring and Southern Autumn - Unnamed Crater</h1><div class="PIA02834" lang="en" style="width:768px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see <a href="/catalog/PIA02394">"The Frosty Rims of Lomonosov Crater in Winter."</a><p>This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02834" onclick="window.open(this.href); return false;" title="Voir l'image PIA02834: The Frosted Craters of Northern Spring and Southern Autumn - Unnamed Crater sur le site de la NASA">Voir l'image PIA02834: The Frosted Craters of Northern Spring and Southern Autumn - Unnamed Crater sur le site de la NASA.</a></div>
PIA02834: The Frosted Craters of Northern Spring and Southern Autumn - Unnamed Crater
<h1>PIA02835: The Frosted Craters of Northern Spring and Southern Autumn - Barnard Crater</h1><div class="PIA02835" lang="en" style="width:393px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see <a href="/catalog/PIA02394">"The Frosty Rims of Lomonosov Crater in Winter."</a><p>This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02835" onclick="window.open(this.href); return false;" title="Voir l'image PIA02835: The Frosted Craters of Northern Spring and Southern Autumn - Barnard Crater sur le site de la NASA">Voir l'image PIA02835: The Frosted Craters of Northern Spring and Southern Autumn - Barnard Crater sur le site de la NASA.</a></div>
PIA02835: The Frosted Craters of Northern Spring and Southern Autumn - Barnard Crater
<h1>PIA02836: The Frosted Craters of Northern Spring and Southern Autumn - Lowell Crater</h1><div class="PIA02836" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see <a href="/catalog/PIA02394">"The Frosty Rims of Lomonosov Crater in Winter."</a><p>This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02836" onclick="window.open(this.href); return false;" title="Voir l'image PIA02836: The Frosted Craters of Northern Spring and Southern Autumn - Lowell Crater sur le site de la NASA">Voir l'image PIA02836: The Frosted Craters of Northern Spring and Southern Autumn - Lowell Crater sur le site de la NASA.</a></div>
PIA02836: The Frosted Craters of Northern Spring and Southern Autumn - Lowell Crater
<h1>PIA02839: Layered Outcrops of Far West Candor Chasma</h1><div class="PIA02839" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/PIA02839bigfig.jpg"></a><p>Images from Mariner 9 in 1972 revealed that some of the mesas and mounds found within the chasms of the martian "Grand Canyon"--the Valles Marineris--have layers in them. Speculations as to the origin of these interior layered materials ranged from volcanic ash deposits to sediments laid down in lakes that could have partially filled the Vallis Marineris troughs, much as lakes now occupy portions of the rift valleys of eastern Africa. The proposal that the Valles Marineris once hosted deep martian lakes led to additional speculation as to the prospects for finding fossil evidence of martian life.<p>Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images have ten or more times better resolution than the Mariner 9 and Viking orbiter images taken in the 1970s. MOC images have indeed confirmed the presence of layered outcrops within the Valles Marineris. They have also shown places previously not suspected to have layered rock, and they have shown that these materials might not have formed in the Valles Marineris, but were instead deposited in craters that were subsequently buried long before the chasms opened up (see discussion below). The layered rock is now visible because of faulting and erosion.<p>The high resolution picture shown here (B, above right) was the first image received by MOC scientists that began to hint at a larger story of layered sedimentary rock on Mars. The picture shows a 1.5 km by 2.9 km (0.9 mi by 1.8 mi) area in far southwestern Candor Chasma (A, above left) that was--based on Mariner 9 and Viking orbiter images--not previously expected to exhibit layers. The MOC image reveals that the floor of western Candor Chasma at this location is indeed layered. What is most striking about the picture is the large number and uniformity of the layers, or beds. There are over 100 beds in this area, and each has about the same thickness (estimated to be about 10 meters (11 yards) thick). Each layer has a relatively smooth upper surface, and each is hard enough to form steep cliffs at its margins.<p>Layers indicate change. The uniform pattern seen here--beds of similar properties and thickness repeated over a hundred times--suggest that the deposition of materials that made the layers was interrupted at regular or episodic intervals. Patterns like this, when found on Earth, usually indicate the presence of sediment deposited in dynamic, energetic, underwater environments. On Mars, these same patterns could very well indicate that the materials were deposited in a lake or shallow sea. Other MOC images suggest that these layers would not have formed in a lake in Candor Chasma, but instead were deposited in a crater or other basin that existed before Candor Chasma was cut (by faulting and erosion) into the surrounding terrain. However, it is not known for certain that these materials actually formed underwater, for it is possible that there were uniquely Martian processes occurring in the distant past that would mimic the pattern of sedimentation in water. For example, if the early Martian atmosphere was denser than it is today, and if the planet's atmospheric pressure changed on a cyclic basis (as it does today), then perhaps these materials are simply deposits of airborne dust that were later buried and cemented to create cliff-forming rock.<p>Sunlight illuminates both the wide angle context view and the narrow angle high resolution image from the left/upper left. In both, north is toward the top and east to the right.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02839" onclick="window.open(this.href); return false;" title="Voir l'image PIA02839: Layered Outcrops of Far West Candor Chasma sur le site de la NASA">Voir l'image PIA02839: Layered Outcrops of Far West Candor Chasma sur le site de la NASA.</a></div>
PIA02839: Layered Outcrops of Far West Candor Chasma
<h1>PIA02840: Layered Material in West Arabia Terra Crater</h1><div class="PIA02840" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/PIA02840bigfig.jpg"></a><p>Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.<p>The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (PIA02840, <a href="/catalog/PIA02841">PIA02841</a>, <a href="/catalog/PIA02842">PIA02842</a>) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in <a href="/catalog/PIA02841">PIA02841</a> and <b>PIA02840</b> (this release) is windblown sand; in <b>PIA02840</b> (this release), this sand enhances the appearance of the layers.<b>Note:</b> In the context image above, the boxes marked A, B, and C refer to <a href="/catalog/PIA02842">PIA02842</a>, <a href="/catalog/PIA02841">PIA02841</a>, and <b>PIA02840</b> (this release) respectively.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02840" onclick="window.open(this.href); return false;" title="Voir l'image PIA02840: Layered Material in West Arabia Terra Crater sur le site de la NASA">Voir l'image PIA02840: Layered Material in West Arabia Terra Crater sur le site de la NASA.</a></div>
PIA02840: Layered Material in West Arabia Terra Crater
<h1>PIA02841: Layered Material in West Arabia Terra Crater</h1><div class="PIA02841" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/PIA02840bigfig.jpg"></a><p>Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.<p>The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (<a href="/catalog/PIA02840">PIA02840</a>, <b>PIA02841</b> (this release), <a href="/catalog/PIA02842">PIA02842</a>) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in <b>PIA02841</b> (this release) and <a href="/catalog/PIA02840">PIA02840</a> is windblown sand; in <a href="/catalog/PIA02840">PIA02840</a>, this sand enhances the appearance of the layers.<b>Note:</b> In the context image above, the boxes marked A, B, and C refer to <a href="/catalog/PIA02842">PIA02842</a>, <b>PIA02841</b> (this release), and (<a href="/catalog/PIA02840">PIA02840</a> respectively.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02841" onclick="window.open(this.href); return false;" title="Voir l'image PIA02841: Layered Material in West Arabia Terra Crater sur le site de la NASA">Voir l'image PIA02841: Layered Material in West Arabia Terra Crater sur le site de la NASA.</a></div>
PIA02841: Layered Material in West Arabia Terra Crater
<h1>PIA02842: Layered Material in West Arabia Terra Crater</h1><div class="PIA02842" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/PIA02840bigfig.jpg"></a><p>Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.<p>The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (<a href="/catalog/PIA02840">PIA02840</a>, <a href="/catalog/PIA02841">PIA02841</a>, PIA02842 (this release)) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in <a href="/catalog/PIA02841">PIA02841</a> and <a href="/catalog/PIA02840">PIA02840</a> is windblown sand; in <a href="/catalog/PIA02840">PIA02840</a>, this sand enhances the appearance of the layers.<b>Note:</b> In the context image above, the boxes marked A, B, and C refer to PIA02842 (this release), <a href="/catalog/PIA02841">PIA02841</a> and (<a href="/catalog/PIA02840">PIA02840</a>) respectively.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02842" onclick="window.open(this.href); return false;" title="Voir l'image PIA02842: Layered Material in West Arabia Terra Crater sur le site de la NASA">Voir l'image PIA02842: Layered Material in West Arabia Terra Crater sur le site de la NASA.</a></div>
PIA02842: Layered Material in West Arabia Terra Crater
<h1>PIA02846: Sediment History Preserved in Gale Crater Central Mound</h1><div class="PIA02846" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2-262bigfig.jpg"></a><p>While many of the layered outcrops in craters and chasms on Mars are seen as stair-stepped series of cliffs and benches composed of similar materials with similar thicknesses, other layer outcrops are expressed on relatively smooth, rounded slopes as alternating light and dark bands. The best example of this variety of layered sedimentary material is found in southern Holden Crater. Holden is located at 26.5°S, 33.9°W, and has a diameter of 141 km (88 mi). The context picture above, shows that a valley, Uzboi Vallis, enters the crater on its southwestern side. Not too far from where Uzboi Vallis meets Holden Crater, rounded slopes and buttes consisting of alternating light and dark bands are seen. The origin of these layers is not known, but like those found in other craters on Mars, they might have resulted from deposition of sediment in a lake that would have occupied Holden Crater. Alternatively, these are materials deposited by falling out of the air, the same way that volcanic ash is deposited on Earth. The Viking mosaic (above) images are illuminated by sunlight from the upper right. The MOC image (top left) is illuminated from the upper left. North is up.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02846" onclick="window.open(this.href); return false;" title="Voir l'image PIA02846: Sediment History Preserved in Gale Crater Central Mound sur le site de la NASA">Voir l'image PIA02846: Sediment History Preserved in Gale Crater Central Mound sur le site de la NASA.</a></div>
PIA02846: Sediment History Preserved in Gale Crater Central Mound
<h1>PIA02918: Mars at Ls 25°: Acidalia/Mare Erythraeum</h1><div class="PIA02918" lang="en" style="width:640px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>14 March 2006<br />This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 25° during a previous Mars year. This month, Mars looks similar, as Ls 25° occurs in mid-March 2006. The picture shows the Acidalia/Mare Erythraeum face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360° around the Sun in 1 Mars year. The year begins at Ls 0°, the start of northern spring and southern autumn.</p><p>Season: Northern Spring/Southern Autumn </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02918" onclick="window.open(this.href); return false;" title="Voir l'image PIA02918: Mars at Ls 25°: Acidalia/Mare Erythraeum sur le site de la NASA">Voir l'image PIA02918: Mars at Ls 25°: Acidalia/Mare Erythraeum sur le site de la NASA.</a></div>
PIA02918: Mars at Ls 25°: Acidalia/Mare Erythraeum
<h1>PIA02979: Mariner Crater</h1><div class="PIA02979" lang="en" style="width:600px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Mariner 4 image of the crater named after it, the 151 km diameter Mariner crater at 35 S, 164 W. Running from the lower left corner of the frame through the bottom of the crater is a linear ridge which is part of Sirenum Fossae. The image was taken from 12,600 km and covers 250 km by 254 km. North is up. (Mariner 4, frame 11E)<p>Mariner 4 was the first spacecraft to get a close look at Mars. Flying as close as 9,846 kilometers (6,118 miles), Mariner 4 revealed Mars to have a cratered, rust-colored surface, with signs on some parts of the planet that liquid water had once etched its way into the soil.<p>Mariner 4 was launched on November 28, 1964 and arrived at Mars on July 14, 1965.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02979" onclick="window.open(this.href); return false;" title="Voir l'image PIA02979: Mariner Crater sur le site de la NASA">Voir l'image PIA02979: Mariner Crater sur le site de la NASA.</a></div>
PIA02979: Mariner Crater
<h1>PIA02980: Atlantis Region on Mars - Mariner 4</h1><div class="PIA02980" lang="en" style="width:479px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Eleventh picture of Mars from Mariner 4 (in "raw" state) taken through the green filter from 7800 miles away showing a crater 75 miles in diameter in the Atlantis region.<p>Mariner 4 was the first spacecraft to get a close look at Mars. Flying as close as 9,846 kilometers (6,118 miles), Mariner 4 revealed Mars to have a cratered, rust-colored surface, with signs on some parts of the planet that liquid water had once etched its way into the soil.<p>Mariner 4 was launched on November 28, 1964 and arrived at Mars on July 14, 1965.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02980" onclick="window.open(this.href); return false;" title="Voir l'image PIA02980: Atlantis Region on Mars - Mariner 4 sur le site de la NASA">Voir l'image PIA02980: Atlantis Region on Mars - Mariner 4 sur le site de la NASA.</a></div>
PIA02980: Atlantis Region on Mars - Mariner 4
<h1>PIA02981: Mars full disk approach view from Mariner 7</h1><div class="PIA02981" lang="en" style="width:640px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">View of the entire planet of Mars from Mariner 7, showing NIX Olympia (later identified as the giant shield volcano Olympus Mons), and polar caps. Photographed from 200,000 miles away.<p>The Mariner 7 spacecraft and its twin (Mariner 6) were designed specifically to concentrate on Mars. Better quality imaging was planned to give a more complete picture of the Martian surface to help in planning future missions to Mars to search for signs of life.<p>Mariner 7 was launched on March 27, 1969 and arrived on August 4, 1969.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02981" onclick="window.open(this.href); return false;" title="Voir l'image PIA02981: Mars full disk approach view from Mariner 7 sur le site de la NASA">Voir l'image PIA02981: Mars full disk approach view from Mariner 7 sur le site de la NASA.</a></div>
PIA02981: Mars full disk approach view from Mariner 7