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PSP_006477_1745_RED_abrowse-00~0.jpgDD Tracks in Southern Schiaparelli Basin (context frame - False Colors; credits: Lunexit)57 visiteDust-Devils (DD) are vortices of wind that form when air rising from a warm surface encounters shear in the above atmosphere.
Martian Dust-Devils can attain gargantuan proportions, reaching the size of terrestrial tornadoes with plumes that tower up to 9 Km above the surface.
Dust-Devils play an important role in sustaining the aerosols that make up Mars’ Red Sky and in cleaning the Martian Surface after a Dust Storm.
Nota Lunexit: sono quindi i DD, secondo la NASA, la "causa maggiore" del Cielo Rosso di Marte? Interessante riflessioni ed interessante quesito: dunque il Cielo di Marte NON E', naturalmente, "rosso" o "arancio", ma è "tinto di rosso/arancio"!
Pensateci sopra...
MareKromium
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PSP_009488_1745_RED_abrowse-01.jpgMartian Caves (edm n. 1 - possible natural colors; credits: Lunexit)57 visiteThe pair of Pit Craters visible here are the smallest “anomalous” pits known to exist at this time. These have either vertical or sub-vertical interior walls (sub-vertical means that they are not visible from a nearly overhead viewing perspective), and each pit is deep enough that sunlight does not hit the floor when the Sun is at or near the Zenith.
Unfortunately, the only thermal-infrared camera currently orbiting Mars cannot resolve features this small, so the temperature characteristics of these pits must remain unknown for now, underscoring the need for a high-resolution thermal instrument on future missions.
Intriguingly, when pit craters on Earth have similar characteristics to the pair shown here, they often have cave entrances in their bases connecting to large underground networks. Current investigations are determining whether the anomalous Martian Pits may be shown to contain such entrances.MareKromium
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PSP_009488_1745_RED_abrowse-00.jpgMartian Caves (ctx frame - possible natural colors; credits: Lunexit)57 visitePit Craters exist in Volcanic Regions across Mars, and form when surface materials collapse into large underground cavities. Such pits are generally bowl-shaped, filled with sediment, and are relatively shallow when compared with their diameters.
Recently, a small number of anomalous Pit Craters were identified with strikingly different visible and thermal characteristics such as: sheer cliff walls; deep interiors that can extend out-of-sight beneath the surface and temperature fluctuations that behave unlike any known feature on Mars.MareKromium
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PSP_009739_2580_RED_abrowse-2.jpgResidual Ice (edm - natural colors; credits: Lunexit)57 visiteIl dettaglio, palese tanto nella versione in b/n del frame, quanto in quella a colori naturali, è stato individuato dal bravissimo Dr Barca e, inizialmente, ci ha fatto pensare ad una possibile estrusione d'acqua la quale, poco dopo essere stata "espulsa", si è rapidamente congelata.
Ma sbagliavamo, poichè non si tratta, a nostro parere, del residuo di un fenomeno estrusivo.
Non lo è, perchè le estrusioni d'acqua (e fango) si manifestano - di solito, e "visivamente" - con accumuli caotici di blocchi di ghiaccio sporco di varie dimensioni intorno ad un'area di ghiaccio più limpido la quale è compatta e posizionata centralmente rispetto agli altri blocchi e blocchetti (provate a visualizzare, per capire bene, la conseguenza di uno "spruzzo" - tipo geyser - di acqua e fango, con l'acqua che poi gela rapidamente).
In Islanda, se volete, si può vedere qualcosa di simile.
Nel nostro caso di specie, comunque, si può dire che la posizione del dettaglio in oggetto è indicativa di un'area su cui si trova del semplice ghiaccio "sporco" (ghiaccio d'acqua, a giudicare dall'albedo e dal colore) residuale, sfuggito al disgelo grazie alla protezione offertagli dalla duna che lo sovrasta.
La configurazione delle dune che caratterizzano la zona, inoltre, ci dice che l'area gelata è posizionata su una superficie decisamente più bassa rispetto al Datum medio della regione, e quindi con niente (o poco) Sole che scioglie e niente (o poco) vento che "gratta & smuove".
Un accumulo di ghiaccio, quindi, destinato a "sopravvivere" MOLTO a lungo!...MareKromium
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PSP_010012_2225_RED_abrowse-01.jpgDeep Rocks Unveiled at Bonestell Crater (edm; natural colors; credits: Lunexit)57 visiteThis edm (437x500 mt or 479x547 yards) of the HiRISE image shows a portion of Bonestell's Central Peak. HiRISE reveals details in the structure and color of these deep rocks that will help scientists decipher the origin and history of the Northern Lowlands.MareKromium
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PSP_010012_2225_RED_abrowse-00.jpgDeep Rocks Unveiled at Bonestell Crater (ctx frame; natural colors; credits: Lunexit)57 visiteImpact craters are sometimes nicknamed “Mother Nature's drill holes” because, thanks to them, deep rock formations are exposed at the surface. Bonestell Crater is a good example.
This image depicts part of the floor of this relatively young impact crater located in the Northern Lowlands. The Northern Lowlands occupy most of the northern half of Mars. They are younger than the Southern Highlands, as shown by the lower number of impact craters, and well below the Planet’s Average Elevation. Their origin is still a mystery.
Bonestell is about 42 Km (approx. 26 miles) in diameter and about 1250 meters (4100 feet) deep. The rocky hills on the floor of this crater constitute its “Central Peak”.
Central peaks form due to elastic rebound of subsurface materials immediately after impact. The rocks in Bonestell's Central Peak may have been 4-to-8 Km below the surface before impact.MareKromium
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PSP_010180_2645_RED_abrowse-00.jpgSmall and young Impact Crater in the NPLD (ctx frame - natural colors; credits: Lunexit)57 visiteThis image shows a small impact crater on the bright North Polar Perennial Ice Cap. Mars has Ice Caps at both its North and South Poles.
The Perennial, or Permanent, portion of the North Polar Cap consists almost entirely of water ice.MareKromium
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PSP_009929_2020_RED_abrowse-00.jpgAncient Layered Rocks in Nili Fossae (ctx frame - natural colors; credits: Lunexit)57 visiteThis image covers a flat plain in the Nili Fossae Region of Mars. The portion shown here is roughly 400 meters, or 1/4 of a mile, across.MareKromium
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Psp_009669_1500_red.jpgConfluence of Valley and Crater (natural colors; credits: Lunexit)57 visiteThis image shows the South-Eastern Rim of a large degraded Impact Crater where a Valley breaches the Crater Rim. The Valley itself, no longer pristine, is difficult to locate in the image.
However, it appears to be in the center, near the right of the Crater Rim. It is possible that this Valley transported water into the Crater, forming a lake in the ancient past.
The scene is peppered with craters of various sizes and states of degradation, indicating that the surface is not young.
A few craters are young enough to still have raised rims. One of these, located on the floor of the larger crater, has distinct raised ejecta radiating out from it.
The crater also has dunes on its floor, indicating that aeolian processes have modified it since it formed.MareKromium
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PSP_007394_1750_RED_abrowse~0.jpgInverted Fluvial Channels and Craters with Ejecta Rays (natural colors; credits: Lunexit)57 visiteThe lower part of this image shows well-defined overlapping channels, which have inverted topography (i.e.: they were once low spots that have been filled in with sediments and now eroded in a such a way that they appear as topographically high regions).
The channels have a winding and intersecting geometry indicating the shifting of the channels over time, a feature consistent with the flow of water in rivers. The channels have small craters that have excavated the channel materials and ejected them to form well-defined rays. There are dark slope streaks (toward the top of the image) showing transport of fine dust down the slope of an eroded bedrock terrain.MareKromium
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PSP_007392_2650_RED_abrowse~0.jpgNorthern Hemisphere Ice Cap (False Colors; credits: Lunexit)57 visiteThis image shows layering within the Northern Hemisphere Ice Cap, which probably reflects seasonal variability in accumulation of the ice versus sublimation (going from solid to a gas).
The presence of sand dunes indicates transport of sedimentary materials by wind. Erosion of layering is apparent as a series of undulating ridges at the transition between the Layered Terrain and the Dune-Field.
Near the top of the image several vents occur where materials from the shallow subsurface are erupted onto the surface. MareKromium
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PSP_006487_1580_RED.jpgCollapse Features in Tyrrhena Patera (natural colors; credits: Lunexit)57 visiteIn this image you can notice a set of craters around the rim of Tyrrhena Patera. Tyrrhena Patera is a volcano in the Southern Highlands with shallow slopes, and only 2 Km (about 1,2 miles) of vertical relief.
The craters are aligned and are known as Pit Crater Chains. These are common in Volcanic Regions on Mars.
They are not formed by a meteorite impact, but by collapse into some void space underground.
Because the Pit Crater Chains and Concentric Fractures are generally aligned, these are most likely due to extension in the Region, where parts of the Martian Crust pull apart during growth of the volcano or emplacement of dikes.
Another way pit crater chains can occur is when Lava Tubes partially collapse forming chains of holes along the roof of the Lava Tubes themselves.
A third possibility is that these may be associated with collapse of the underground magma chamber.MareKromium
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