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http://photojournal.jpl.nasa.gov/jp...5470_modest.jpg

Citation: This spectrum, taken by the Mars Exploration Rover Opportunity's Moessbauer spectrometer, shows the presence of an iron-bearing mineral called jarosite in the collection of rocks dubbed "El Capitan." "El Capitan" is located within the rock outcrop that lines the inner edge of the small crater where Opportunity landed. The pair of yellow peaks specifically indicates a jarosite phase, which contains water in the form of hydroxyl as a part of its structure. These data suggest water-driven processes exist on Mars. Three other phases are also identified in this spectrum: a magnetic phase (blue), attributed to an iron-oxide mineral; a silicate phase (green), indicative of minerals containing double-ionized iron (Fe 2+); and a third phase (red) of minerals with triple-ionized iron (Fe 3+).

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http://photojournal.jpl.nasa.gov/jp...5473_modest.jpg
PIA05473.jpg (43.92 kB) http://photojournal.jpl.nasa.gov/jpeg/PIA05473.jpg

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, shows a geological feature dubbed "Robert E." Light from the top is illuminating the feature, which is located within the rock outcrop at Meridiani Planum, Mars. Several images, each showing a different part of "Robert E" in good focus, were merged to produce this view. The area in this image, taken on Sol 15 of the Opportunity mission, is 2.2 centimeters (0.8 inches) across.

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http://photojournal.jpl.nasa.gov/jp...5474_modest.jpg
PIA05474.tif (184.9 kB) http://photojournal.jpl.nasa.gov/tiff/PIA05474.tif

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, shows a geological region of the rock outcrop at Meridiani Planum, Mars dubbed "El Capitan." Light from the top is illuminating the region. Several images, each showing a different part of this region in good focus, were merged to produce this view. The area in this image, taken on Sol 28 of the Opportunity mission, is 1.3 centimeters (half an inch) across.

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http://photojournal.jpl.nasa.gov/jp...5475_modest.jpg
PIA05475.tif (256.5 kB) http://photojournal.jpl.nasa.gov/tiff/PIA05475.tif

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, shows a geological region of the rock outcrop at Meridiani Planum, Mars dubbed "El Capitan." Light from the top is illuminating the region. Several images, each showing a different part of this region in good focus, were merged to produce this view. The area in this image, taken on Sol 28 of the Opportunity mission, is 1.5 centimeters (0.6 inches) across.

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http://photojournal.jpl.nasa.gov/jp...5476_modest.jpg
PIA05476.tif (1.047 MB) http://photojournal.jpl.nasa.gov/tiff/PIA05476.tif

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, shows a geological region of the rock outcrop at Meridiani Planum, Mars dubbed "El Capitan." The region was in a shadow when the image was acquired. Several images, each showing a different part of this region in good focus, were merged to produce this view. The area in this image, taken on Sol 28 of the Opportunity mission, is approximately 3 centimeters (1.2 inches) across.

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http://photojournal.jpl.nasa.gov/jp...5478_modest.jpg
PIA05478.tif (3.15 MB) http://photojournal.jpl.nasa.gov/tiff/PIA05478.tif

Citation: This image, taken by the panoramic camera on the Mars Exploration Rover Opportunity, shows a close up of the rock dubbed "El Capitan," located in the rock outcrop at Meridiani Planum, Mars. This image shows fine, parallel lamination in the upper area of the rock, which also contains scattered sphere-shaped objects ranging from 1 to 2 millimeters (.04 to .08 inches) in size. There are also more abundant, scattered vugs, or small cavities, that are shaped like discs. These are about 1 centimeter (0.4 inches) long.

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http://photojournal.jpl.nasa.gov/jp...5484_modest.jpg
PIA05484.tif (712.3 kB) http://photojournal.jpl.nasa.gov/tiff/PIA05484.tif

Citation: This image taken by the Mars Exploration Rover Opportunity's panoramic camera shows the eastern plains that stretch beyond the small crater where the rover landed. In the distance, the rim of a larger crater dubbed "Endurance" can be seen. This color mosaic was taken on the 32nd martian day, or sol, of the rover's mission and spans 20 degrees of the horizon. It was taken while Opportunity was parked at the north end of the outcrop, in front of the rock region dubbed "El Capitan" and facing east. The features seen at the horizon are the near and far rims of "Endurance," the largest crater within about 6 kilometers (4 miles) of the lander. Using orbital data from the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft, scientists estimated the crater to be 160 meters (175 yards) in diameter, and about 720 meters (half a mile) away from the lander. The highest point visible on "Endurance" is the highest point on the far wall of the crater; the sun is illuminating the inside of the far wall. Between the location where the image was taken at "El Capitan" and "Endurance" are the flat, smooth Meridiani plains, which scientists believe are blanketed in the iron-bearing mineral called hematite. The dark horizontal feature near the bottom of the picture is a small, five-meter (16-feet) crater, only 50 meters (164 feet) from Opportunity's present position. When the rover leaves the crater some 2 to 3 weeks from now, "Endurance" is one of several potential destinations.

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A Trail of Salts


http://photojournal.jpl.nasa.gov/jp...5483_modest.jpg

Citation: This graph shows the relative abundances of sulfur (in the form of sulfur tri-oxide) and chlorine at three Meridiani Planum sites: soil measured in the small crater where Opportunity landed; the rock dubbed "McKittrick" in the outcrop lining the inner edge of the crater; and the rock nicknamed "Guadalupe," also in the outcrop. The "McKittrick" data shown here were taken both before and after the rover finished grinding the rock with its rock abrasion tool to expose fresh rock underneath. The "Guadalupe" data were taken after the rover grounded the rock. After grinding both rocks, the sulfur abundance rose to high levels, nearly five times higher than that of the soil. This very high sulfur concentration reflects the heavy presence of sulfate salts (approximately 30 percent by weight) in the rocks. Chloride and bromide salts are also indicated. Such high levels of salts strongly suggest the rocks contain evaporite deposits, which form when water evaporates or ice sublimes into the atmosphere.

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http://photojournal.jpl.nasa.gov/jp...5480_modest.jpg

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, shows an extreme close-up of the "El Capitan" region, part of the rock outcrop at Meridiani Planum, Mars. As seen in panoramic images of "El Capitan," this region appears laminated, or composed of layers of firmly united material. The upper left portion of this image shows how the grains of the region might be arranged in planes to create such lamination. At the upper right, in the zone surrounding two larger sphere-shaped particles, this image also shows another apparent characteristic at the scale of individual grains. The granularity of the matrix -- the rock in which the spherules are embedded -- is modified near the spherules compared with grains farther from the spherules. Around the upper spherule, the grain size is increased. This change in grain size might represent a "reaction rim," a feature produced by fluid interaction with the matrix material adjacent to the spherule during the growth of the spherule.

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Citation: This image taken by the Mars Exploration Rover Opportunity's panoramic camera shows the rock nicknamed "Last Chance," which lies within the outcrop near the rover's landing site at Meridiani Planum, Mars. The image provides evidence for a geologic feature known as ripple cross-stratification. At the base of the rock, layers can be seen dipping downward to the right. The bedding that contains these dipping layers is only one to two centimeters (0.4 to 0.8 inches) thick. In the upper right corner of the rock, layers also dip to the right, but exhibit a weak "concave-up" geometry. These two features -- the thin, cross-stratified bedding combined with the possible concave geometry -- suggest small ripples with sinuous crest lines. Although wind can produce ripples, they rarely have sinuous crest lines and never form steep, dipping layers at this small scale. The most probable explanation for these ripples is that they were formed in the presence of moving water.

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http://photojournal.jpl.nasa.gov/jp...5481_modest.jpg

Citation: This image, taken by the microscopic imager onboard the Mars Exploration Rover Opportunity, shows a close-up of the region dubbed "El Capitan," which lies within the rock outcrop at Meridiani Planum, Mars. In the lower left, a spherule, or sphere-shaped grain, can be seen penetrating the interior of a small cavity called a vug. This "cross-cutting" relationship allows the relative timing of separate events to be established. In this case, the spherule appears to "invade" the vug, and therefore likely post-dates the vug. This suggests that the spherules may have been one of the last features to form within the outcrop.

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http://photojournal.jpl.nasa.gov/jp...5492_modest.jpg
PIA05492.tif (12.77 MB) http://photojournal.jpl.nasa.gov/tiff/PIA05492.tif

Citation: This mosaic of images taken by the panoramic camera onboard the Mars Exploration Rover Opportunity shows the rock region dubbed "El Capitan," which lies within the larger outcrop near the rover's landing site. "El Capitan" is being studied in great detail using the scientific instruments on the rover's arm; images from the panoramic camera help scientists choose the locations for this compositional work. The millimeter-scale detail of the lamination covering these rocks can be seen. The face of the rock to the right of the mosaic may be a future target for grinding with the rover's rock abrasion tool.

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http://photojournal.jpl.nasa.gov/jp...5493_modest.jpg
PIA05493.tif (1.768 MB) http://photojournal.jpl.nasa.gov/tiff/PIA05493.tif


Vugs Provide Clues to Martian Past

Citation: This image, taken by the microscopic imager on the Mars Exploration Rover Opportunity, illustrates the shapes of the vugs, or small cavities, located on the region dubbed "El Capitan." The region is part of the rock outcrop at Meridiani Planum, Mars, which the rover is currently examining. The image provides insight into the nature of the rock matrix -- the rock material surrounding the vugs. Several vugs have disk-like shapes with wide midpoints and tapered ends. This feature is consistent with sulfate minerals that crystallize within a rock matrix, either pushing the matrix grains aside or replacing them. These crystals are then either dissolved in water or eroded by wind activity to produce vugs. The rock matrix here exhibits a granular texture, delicately enhanced through wind abrasion. The primary sediment particles making up this granular layer are relatively uniform in size, ranging up to 1 millimeter (.04 inches). Note that some of these grains are well rounded, which could result from transport of rock fragments in air or water, or precipitation of mineral grains in water.

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Solacin

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Ayé, ils commencent enfin à avoir des débuts de preuves géologiques sur une "anté-présence" d'eau à la surface de Mars
Bravo la NASA pour tout ça

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Oui, c'est super cool

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