Mars Reconnaissance Orbiter (MRO)
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PSP_006714_2255_RED_abrowse.jpgLandslide Deposit below a small Knob in Deuteronilus Mensae (MULTISPECTRUM; credits: Lunexit)53 visiteThis image shows a possible Landslide Deposit originating from a mesa just East of the center of the scene in Deuteronilus Mensae.
The deposit is the lobe-shaped feature extending across the center of the image. Located at approx. 45° North, where ground ice is thought to be stable, it is possible that the deposit formed from "Mass Wasting" of ice-rich material.
Mass Wasting is a process driven by gravity that moves material downslope; the ice enhances the process.
The lobe has distinct textures. It is bouldery at some locations and pitted or wrinkled at others. The pitted texture may be due to desiccation (drying) of soil that can occur when ice from beneath the surface sublimates and leaves empty spaces into which the surface collapses.MareKromium
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PSP_006724_2165_RED_abrowse-PCF-LXTT.jpgUnnamed Channel in Utopia Planitia (Absolute Natural Colors; credits for the additional process. and coloring: Dr Paolo C. Fienga - Lunexit Team)235 visiteSeen here are gullies in an Unnamed Northern Crater. The Crater is well-preserved as indicated by its sharp Rim and steep Walls.
Gullies are rarer in the Northern Hemisphere, possibly because there are fewer Slopes for them to form on compared to the heavily cratered Southern Highlands.
This image captures a wide range of Gully morphologies. The Gullies on the North Wall (such as the South-facing Wall) are more abundant and evenly-spaced than those on the East and South Walls and they extend up to the Crater Rim on the northern side. These differences might occur because of differences in sunlight exposure and temperature variations.
The Crater Floor has a linear texture suggestive of flow. Ice-rich material might have moved off the Crater Walls, driven by gravity, and flowed towards the Crater center.MareKromium
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PSP_006742_2050_RED_abrowse.jpgClays in Mawrth Vallis (MULTISPECTRUM; credits: Lunexit)103 visiteMawrth Vallis is one of the most colorful parts of Mars. However, it is not quite as colorful as seen in this observation, where this “extra” color comes from the fact that HiRISE can “see” into part of the infrared, enhancing its ability to detect color differences that are indicative of various minerals.
Properly identifying those minerals is where the CRISM instrument excels.
They show that this area has a variety of different types of clay minerals: these are especially interesting because they had to form when water was interacting with rocks.
The different types of clays point to different water chemistries and temperatures.
With HiRISE, we can better pinpoint how these different materials are distributed across the surface. Furthermore, by taking two images we can produce a stereo image and see the topography, allowing the different clay-bearing layers to be traced in 3D. MareKromium
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PSP_006752_1525_RED_abrowse-PCF-LXTT2.jpgFeatures of Terby Crater (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)85 visitenessun commentoMareKromium
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PSP_006760_1370_RED_abrowse.jpgGullies in Terra Sirenum (MULTISPECTRUM; credits: Lunexit)72 visiteThis image shows Pole-Facing Gullies in a Southern Hemisphere Crater. Gullies are young features that are widely thought to form from fluvial processes involving liquid water. These particular gullies have very fine channels, including some that intersect and overlap. This is evidence that multiple flow events occurred within the Gullies.
The wavy, arcuate ridges at the bottom of the slope may have formed by gravity moving ice-rich material off the crater wall.
The pitted texture of the crater floor suggests that volatiles (ices that easily turn into gas) escaped from the subsurface, causing the surrounding material to collapse and form small pits.
Coord.: 42,6° South Lat. and 214,8° East Long.
Spacecraft altitude: about 254 Km
M.L.T.: 14:38 (early afternoon)MareKromium
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PSP_006769_1595_RED_abrowse.jpgSouthern Highlands Panorama (Enhanced Natural Colors; credits: Lunexit)54 visiteThis image shows a portion of the Southern Highlands cut by Arda Valles, an ancient Valley Network.
The Valley Network is degraded as seen by the lack of obvious walls and a V-shaped bottom. The valley networks are thought to have formed by running liquid water on the surface of Mars billions of years ago, with a few being active more recently.
Arda Valles has many dunes within it and craters on top of it, which show that is has been around for long enough for craters to form. The surface that Arda Valles cuts is more cratered than the valley surface because wind has moved material into the valley throughout time such that the surface in the valley gets covered and past craters might be buried there.MareKromium
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PSP_006770_1760_RED_abrowse-00.jpgInverted Channels, North of Juventae Chasma (context frame - MULTISPECTRUM; credits: Lunexit)53 visiteThis image shows raised ridges on a plain to the North of Juventae Chasma. Juventae Chasma, a canyon that is part of the Valles Marineris Canyon System, stretches for about 180 Km (approx. 110 miles) from East to West and about 250 Km (approx. 155 mi) from North to South.
Several examples of raised features have been identified on the plains near this canyon.
In this location, it is most likely that water - either pure or salt water - once flowed through these channels and deposited sediments that eventually filled the channels and became cemented by some chemical precipitating from the flowing water.
Over time, wind eroded the surrounding surface leaving the remnant channels exposed as raised ridges.MareKromium
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PSP_006770_1760_RED_abrowse-01.jpgInverted Channels, North of Juventae Chasma (extra-detail mgnf)53 visiteThe raised ridges in this image have been explained as former stream channels that are now preserved in inverted relief.
On Earth, inverted relief occurs when former depressions become elevated because materials that fill the depressions are more resistant to erosion than the surrounding terrain.
For example: a depression may become filled with lava that is more resistant to erosion than the surrounding surface; gravel or boulders transported in a high energy flow protect underlying material from erosion, or sediments deposited by a flowing stream become cemented.MareKromium
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PSP_006806_2215_RED_abrowse~0.jpgRelict Glacial Landform in Deuteronilus Mensae (MULTISPECTRUM; credits: Lunexit)56 visiteThis image shows remnant raised margins and other interior structures of a lobate flow feature emanating the mouth of an alcove along a mesa in Deuteronilus Mensae.
This region of Mars has many features called “lobate debris aprons” that spread out below the scarps of polygonal mesas. Many of the debris aprons have what appear to be lineations or grooves that are parallel to their movement direction indicating flow of the materials.
The flow may be due to the presence of ice in the material. Recent data from the Shallow Radar instrument (SHARAD) on the Mars Reconnaissance Orbiter Spacecraft has indicated a large reservoir of subsurface ice in the Deuteronilus Mensae Region that supports the observational evidence of surface flow.MareKromium
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PSP_006820_1760_RED_abrowse~0.jpgPeri-Equatorial "Sand-Patches" on a Crater Floor (MULTISPECTRUM; credits: Lunexit)53 visiteThis image shows part of the floor of a large crater in Arabia Terra, near Mars’ Equator. A notable feature on this crater floor is a region of "Dark Patches" up to about 100 mt (330 feet) across. These Dark Patches sit in an area of connected small ridges and spurs and bury them, filling in the low areas and piling up. In several places light ridge crests protrude through the dark material.
The dark patches appear to be collections of wind-blown sand. Sand on Mars is often dark, likely because it is fragments of a volcanic rock called basalt. (Sand on Earth is most often light-toned quartz). Sand may tend to collect in patches that can ultimately evolve into large dunes if more sand gathers. The patches of sand here are not big enough to form such large structures, but small-scale regular texture due to blowing wind is visible on the surface.
The relatively dark tone which can be seen around the Sand Patches (compared with the surrounding material) is probably due to small amounts of additional sand. In some places this collects at the bottom of troughs.MareKromium
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PSP_006841_1935_RED_abrowse~0.jpgJust like a "Butterfly": Dilly Crater... (MULTISPECTRUM; credits: Lunexit)53 visiteThis image covers the primary cavity of the distinctive rayed crater Dilly. Dilly is what is commonly referred to as a “butterfly” crater. This colloquial name refers to the asymmetry of the ejecta giving the appearance of “wings” around an elliptical cavity, and hence, the overall appearance of a butterfly. The “butterfly” appearance and elliptical cavity of Dilly (approx. 2 x 2,3 Km in diameter) are distinctive clues indicating that the crater formed from a low-angle impact (< 45°), likely from the South-West.
In addition to being a “butterfly” crater, Dilly is one of the smallest of the large rayed crater systems discovered in THEMIS nighttime infrared (temperature) images. Dilly, like its rayed counterparts such as Zunil, Gratteri, Tomini, Zumba, and the recently discovered unnamed crater seen in PSP_003611_1970, possesses distinctive rays (i.e.: spoke-like and far-traversing radial ejecta features) that are most readily viewed in THEMIS images. Crater rays are distinctive in the infrared because they are comprised of both dust and coarse, rocky materials, which are contrasted as cold (dark) and warm (bright) respectively. Because rays are ephemeral features, they are noted by scientists as a tell-tale sign of a fresh or well-preserved crater.
In the image, we can also observe that Dilly possesses a very distinctive light-toned South-West-trending streak that indicates modification by wind.
Light-toned dunes are also visible in the bottom of the crater.MareKromium
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PSP_006891_1970_RED_abrowse-01.jpgAt the base of the Olympus... (EDM - Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)53 visiteThe bottom right part of the cutout has a much flatter and smoother surface. These are younger lava flows that have buried the lower part of the volcano. When lava flows form vast smooth sheets, they are called "flood" lavas.
In the bottom of the cutout, the flood lavas have odd, wiggly looking plateaus. These are parts of the lava crust that were lifted up when more liquid lava was injected into the middle of the slowly solidifying lava flow.
This process is called "inflation" and is seen on many lava flows on Earth. These younger lava flows are cut by two different sets of faults. One makes the branching valley in the flood lavas and the other creates the sinuous ridge and valley along the edge of the Olympus Mons lava flows.
Lower resolution images that cover a broader area suggest that the sinuous fault is an old buried structure that has been more recently reactivated.MareKromium
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