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Psp_009474_1705_red.jpgWater Bearing Minerals in Noctis Labyrinthus (natural colors; credits: Lunexit)57 visiteNoctis Labyrinthus consists of a series of Pits on the western end of the large Valles Marineris Canyon System.
The HiRISE camera and the CRISM Spectrometer have revealed that the floors of some of these Pits exhibit layered rocks, or strata, that contain minerals with water. These Pits were formed several billion years ago, therefore the rocks and sediments on their floors record evidence of water during this period of Mars’ history.
The walls of the Pits are commonly covered with dust and other loose sediments that form dunes and dune-like forms, and in many cases the floors of the pits are also covered with these materials. This image shows an example of light-toned layers exposed beneath these sediments and dunes, and CRISM data show that these layers have hydrated minerals.
The dark-brown/orange tones in this natural color image correspond to areas with more Pyroxene, a mineral found in volcanic rocks and Martian Dust. Some Pits, such as this one, appear to have deposits associated with large landslides that are younger than the hydrated minerals and partially bury them.MareKromiumSet 25, 2008
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PSP_009485_2185_red.jpgClusters of Mounds at Acidalia Planitia (Extremely Enhanced and Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)57 visiteThis HiRISE image shows clusters of light-colored Mounds poking through the Dark Plains of Acidalia. These Mounds are similar in shape and color to mounds identified elsewhere in the Northern Lowlands.
The mounds imaged here are approximately 250 meters (270 yards) across, and most of them have one or more central crater-like depressed areas, looking like terrestrial cinder cones. Terrestrial cinder cones are formed by loose volcanic fragments, mostly gravel- and boulder-size. In contrast, the surface of these Martian Mounds looks cemented rather than bouldery.
There are several hypothesis to explain the origin of these Martian Mounds; all of them require the presence of fluids near or at the surface.
One hypothesis is that these mounds are Hydrothermal Spring edifices like those at Yellowstone. Terrestrial Hydrothermal Spring Mounds form when hot subsurface fluids, loaded with minerals, reach the surface and deposit their load.
Another possible explanation is that these Mounds are "Mud Volcanoes", similar to those found at Trinidad and Tobago. Mud Volcanism occurs when buried wet sediments are subject to high pressures and squeeze out though weak points at the surface.
Some terrestrial "Pseudocraters" are also similar to these Martian Mounds. Pseudocraters form when lava flows over wet terrains or over water bodies. The lava’s heat vaporizes the fluids, which then burst through the lava, producing small explosions and building conical landforms.MareKromiumSet 25, 2008
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PSP_005770_1745_RED_abrowse-00.jpgThe "Martian Black Hole" (False Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)59 visitenessun commento
MareKromiumSet 25, 2008
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PSP_005817_1515_RED_abrowse.jpgBedrock (MULTISPECTRUM; credits: Lunexit)57 visite
This frame shows part of the floor of an unnamed crater in the Southern Highlands, near Hellas Planitia. It depicts light-colored bedrock and darker wind deposits. The bedrock appears tan-colored and shows subtle signs of layering in places (...).
Layering in terrestrial formations usually indicates that the rock-forming materials were deposited by wind or water.
The bedrock is crisscrossed by a dense network of rectilinear (lines that are parallel or at right angles) fractures; some can be followed for hundreds of meters.
The fractures look bluish in color, indicating that they are occupied by materials that are somehow different from the bedrock. Perhaps wind-carried materials got trapped in the depressed fracture zones.
MareKromiumSet 24, 2008
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PSP_006672_1420_RED_abrowse~0.jpgFeatures of the Hellas Montes (MULTISPECTRUM; credits: Lunexit)59 visiteThe Hellas Montes are a group of mountains along the western rim of the giant Hellas Basin on Mars.
The Hellas Basin is the largest of the obvious impact craters on the Red Planet. It is very ancient and has been partially filled by sediments. The Hellas Montes are part of the eroded crater rim.
In the central part of this HiRISE image, we can see steep slopes where landslides have exposed a variety of rocks. The jumble of blocks, rather than stacks of layered sediments or lavas, is consistent with impact crater ejecta. On flatter slopes, the ground is covered with a mantling deposit that is generally considered to be ice-rich dust.
In the southern part of the image (Dx), a large circular depression — rimmed by a zone with many large boulders — is (barely) visible. This is an impact crater with a relatively thin mantling deposit on its rim.
MareKromiumSet 18, 2008
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PSP_006677_1475_RED_abrowse~0.jpgStreamlined Features near Hale Crater (natural colors; credits: Lunexit)59 visiteThis image contains streamlined features located North-West of Hale Crater, a 120 x 150 Km diameter impact crater that is possibly the youngest of its size on Mars.
A streamlined feature is one that is raised, possessing sharp edges. It is narrower at the downstream end because of the flow that carved it. Any fluid — lava, water, mud, and even flowing ice — can form streamlined features. Many portions of the image are filled with craters, while others are rather smooth.
The streamlined features in this image tend to be smoother, suggesting they are relatively young.
Their origin might be related to the impact that formed the crater.
MareKromiumSet 18, 2008
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PSP_006681_1580_RED_abrowse~0.jpgFresh Southern Crater (natural colors; credits: Lunexit)89 visiteThis image features a very fresh crater in the Southern Hemisphere. The crater is termed fresh because it is well-preserved with steep walls and obvious small-scale ejecta.
The crater has a set of dark rays extending from it; these rays are ejecta that sprayed out when the crater formed. Boulders ejected during the impact surround the crater.
MareKromiumSet 17, 2008
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PSP_009295_2565_RED.jpgAbrading Dunes in the North Polar Erg (natural colors; credits: Lunexit)59 visiteThis location is where Mars Global Surveyor (a.k.a.: MGS) saw evidence of dunes that either shrank or completely disappeared over a span of a few years. HiRISE provides new details at higher resolution.
As seen here, the dunes show clear evidence of erosion.
Based on the shape of the dunes in this picture, the strongest winds have blown from the upper right (South-East) to lower left (North-West).
Streamers of dark sand are visible on the white, frost-covered surface downwind of the dunes. This is particularly prominent at the “horns” of the barchan dunes (these are the dunes with the prominent points at their edges).
Scientists believe these dunes are cemented, by ice, such that the wind is progressively eroding them over time. Future observations by HiRISE will determine if the dunes shrink as indicated by MGS, or maybe even migrate, over time.MareKromiumSet 15, 2008
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Psp_009716_1755_red.jpgSurface Features inside Gale Crater (natural colors; credits: Lunexit)58 visitenessun commentoMareKromiumSet 15, 2008
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Psp_009352_1770_red.jpgLight Toned Materials and Plains in Southern Meridiani Planum (Extremely Enhanced Natural Colors; credits: Lunexit)58 visitenessun commentoMareKromiumSet 13, 2008
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Psp_008240_2500_red.jpgLouth Crater South Rim (Extremely Enhanced Natural Colors; credits for the additional process. and color: Dr Paolo C. Fienga - Lunexit Team)59 visitenessun commentoMareKromiumSet 12, 2008
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Psp_008216_2325_red.jpgPeriglacial Surface Features in the Northern Plains (natural colors; credits: Lunexit)57 visitenessun commentoMareKromiumSet 12, 2008
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