Mars Reconnaissance Orbiter (MRO)
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ESP_013726_1475_RED_abrowse.jpgGullies and Flow Features on an Unnamed Crater Wall (Natural Colors; credits: Lunexit)57 visiteThis HiRISE image shows a sample of the variety and complexity of processes that may occur on the walls of Martian Craters, well after the impact crater formed.
At the very top of the image is the high Crater Rim; at the bottom of the image is the Crater's Central Peak - a dome of material rising above the surrounding Crater Floor uplifted during the impact event. Reaching down the Walls of the crater are windy and crooked troughs, or Gullies. Some of these Gullies may have formed with the help of liquid water, melted from ice or snowpack on the Crater Walls or from groundwater within the Walls. Also notable is the long tongue-like lobe stretching down the middle of the image, with a darker, rounded snout, and prominent parallel grooves on its surface. These characteristics, together with faint cracks on its surface, suggest that this lobe may have formed by movement of ice-rich material from up on the Crater Wall down to the floor.
Because surface features on this lobe, as well as most Gullies, do not appear sharp and pristine, and wind-blown dunes have blown up on the front snout of the lobe, and because there are several small craters on the lobe's surface, the movement of ice-rich material, and possibly water, have probably not occurred very recently.
MareKromium
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ESP_013751_1115_RED_abrowse.jpgDD Tracks in Thyles Rupes (Natural Colors; credits: Lunexit)52 visiteThe Dark Streaks are a result of a Surface-Atmosphere interaction that creates thermally-driven Vortices. These Martian Vortices are giant Dust Devils that vacuum the bright Surface dust revealing the darker Subsurface rock.
This image was taken in the late Southern Summer and shows that the Dust Devil direction of movement changes with the winds as the season progresses from Spring to Fall. Dust Devils are sensitive to changes in low-speed ambient winds and will follow the dominant daytime wind direction.
The direction of the Vortex is visible by the scallop pattern that is left behind as a Dust Devil will erase the front part of the circular track as it follows the wind.MareKromium
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ESP_013785_1300_RED_abrowse.jpgColliding Sand Dunes in Aonia Terra (Natural Colors; credits: Lunexit)52 visiteMareKromium
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ESP_013799_1755_RED_abrowse-PCF-LXTT.jpgExtremely "Fresh" Unnamed Rayed-Impact Crater (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)246 visitenessun commentoMareKromium
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ESP_013810_1485_RED_abrowse.jpgRough and highly cratered Southern Terrain (Natural Colors; credits: Lunexit)52 visitenessun commentoMareKromium
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ESP_013948_1410_RED_abrowse-00.jpgUnnamed Craters with Gullies in Sirenum Fossae (Natural Colors; credits: Lunexit)52 visiteThis image covers parts of two different Unnamed Craters, both with Gullies in the Inner Walls. Gullies are a popular target because their formation is still being debated.
The powerful HiRISE camera reveals many details of Gullies that have never been seen before. Some hypotheses about the formation of Gullies involve the flow of some amount of liquid (water, brine, or some other substance - Nota Lunexit: QUALE???), and others postulate that Gullies could be formed by the downhill movement of dry material such as Dust or Sand.
To further complicate things, different Gullies could have formed by different methods.
The many Gullies visible in this image look quite different from each other. This EDM n.1 - from the South/Western part of the Crater to the South - Dx) shows a Gully with a smaller Alcove (source region at the top) and a deep Main Channel. The material in the Channel is a different color than the Alcove, indicating they may contain different minerals or different grain sizes.
Another Gully (EDM n.2), located in the Northern side of the same Crater, has almost no Alcove and very little material deposited at the bottom. However, this Gully is marked by a distinct bright-colored deposit along its length. This could be a sign of recent activity where material has moved downhill.
And yet another site nearby (EDM n.3) within the same Crater has multiple overlapping Gullies of different types. Most of these have large fan-shaped deposits at the bottom, and a few to the left side of the EDM n.3 have bright deposits where new material may have been deposited or exposed.
Some of the Channels and Fans contain Ripples; this might be where wind eroded loose material, or it may be a texture that formed as sand or liquid moved down the slope. Some of the gully-like features in this image are more likely Dry Landslide Chutes (Dust Avalanches).MareKromium
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ESP_013948_1410_RED_abrowse-01.jpgGullies in Sirenum Fossae (EDM n.1 - Natural Colors; credits: Lunexit)52 visitenessun commentoMareKromium
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ESP_013948_1410_RED_abrowse-02.jpgGullies in Sirenum Fossae (EDM n.2 - Natural Colors; credits: Lunexit)52 visitenessun commentoMareKromium
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ESP_013948_1410_RED_abrowse-03.jpgGullies in Sirenum Fossae (EDM n.3 - Natural Colors; credits: Lunexit)52 visitenessun commentoMareKromium
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ESP_013951_1955_RED_abrowse-00.jpgDark Syrtis Major (CTX Frame - Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)52 visiteOn 13 October 1659, Dutch Astronomer Christiaan Huygens turned one of his telescopes towards a bright orange spot in the sky and produced what Percival Lowell would later call the first drawing of Mars worthy of the name ever made by man.
Huygens included a "dark spot" in his drawing that is thought to represent Syrtis Major, a small sliver of which is visible in this HiRISE image.
Syrtis Major is a Shield Volcano and its dark color comes from the dark Basaltic Rock present in the area, visible because it lacks the Dust that paints the rest of the Planet its distinct, rusty orangish color. By tracking this "dark spot" in repeated observations, Huygens concluded that Mars rotated every 24 hours: a time not too far off from its true rotation period of approx. 24 hours and 39,58 minutes.MareKromium
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ESP_013951_1955_RED_abrowse-01.jpgDark Syrtis Major (EDM - Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)52 visiteIn this EDM of Syrtis Major, ancient Noachian Bedrock is exposed. This is rock made in the early Soles of Martian History.
An Impact Crater (about 50 Km in diameter) into this rock exposes Layers along its Wall. These Layers may be made from several different geologic materials, such as Lava Flows, Debris from nearby impact craters, or deposits of Dust or Sand.
They may also represent different periods of deposition and erosion. The Layers are of varying thickness: some of the lighter, resistant units are less than 10 meters thick, while some of the darker layers might be over 100 meters thick.MareKromium
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ESP_013954_1780_RED_abrowse-00.jpgOpportunity near Victoria Crater (Natural - but slightly enhaced - Colors; credits: Lunexit)52 visitenessun commentoMareKromium
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