Mars Reconnaissance Orbiter (MRO)
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ESP_012080_0990_RED_abrowse.jpgPossible Hydration in High Southern Latitudes' Region (Natural Colors; credits: Lunar Explorer Italia)52 visitenessun commentoMareKromium
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ESP_012195_1750_RED_abrowse.jpgMartian Grand Canyon! (Natural Colors; credits: Lunar Explorer Italia)52 visitenessun commentoMareKromium
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ESP_012198_0975_RED_abrowse.jpgSouth Polar Icy Features (Natural Colors; credits: Lunar Explorer Italia)52 visitenessun commentoMareKromium
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ESP_012202_1390_RED_abrowse.jpgDunes in Western Nereidum Montes (Extremely Enhanced Natural Colors; credits: Lunar Explorer Italia)52 visitenessun commentoMareKromium
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ESP_012226_1815_RED_abrowse.jpgDark Sands Deposits or Surfacing Hydrocarbons? (Natural Colors; credits: Lunar Explorer Italia)65 visitenessun commentoMareKromium
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ESP_012251_0935_RED_abrowse.jpgJust like Magnetic Fields (Natural Colors; credits: Lunar Explorer Italia)53 visitenessun commentoMareKromium
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ESP_012252_1245_RED_abrowse.jpgDust Devils Tracks (Natural Colors; credits: Lunar Explorer Italia)73 visiteThis image is located in a crater in the Hellespontus region that displays dunes and dust devil tracks.
The larger barchan-like dunes are surrounded by linear ripples and dark coarse material. The dunes are composed of basaltic sands that have accumulated in the troughs of the dunes. The dunes themselves run in a northeast to southwest direction. The steep west facing slip face indicates that the dune is controlled by a southeasterly direction and that the winds here tend to blow from left to right.
Both the sandy and rough textured surfaces are crisscrossed by the tracks of dust devils. These tracks form when dust devils abrade the surface exposing the underlying darker surface. The tracks appear to be clustered since dust devils frequently form in areas that have been previously scoured. The lighter tracks are older tracks that are fading or have been overprinted by other dust devils.
It is possible that the dunes are stable as many of the dust devils appear to be going to the southeast direction (based on scallop patterns- dust devil leaves behind dark circular patterns and erase the frost as it moves forward by local winds). This is an indication of change of wind especially since the dune field is in a crater.
MareKromium
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ESP_012265_0950_RED_abrowse.jpgGiza Region (Natural Colors; credits: Lunar Explorer Italia)53 visitenessun commentoMareKromium
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ESP_012270_2035_RED_abrowse.jpgFlood-Carved Rock in Olympica Fossae (Natural Colors; credits: Lunar Explorer Italia)53 visiteThis HiRISE image is part of the Olympica Fossae in the Tharsis Region of Mars.
Tharsis is most famous for being the home of the four largest Volcanoes in the Solar System. However, the Region also hosts a variety of other geologic features formed as the ground deformed under the tremendous weight of the Volcanoes.
Most of the Fissures (or “Fossae”) in the Region are primarily places where the ground was pulled apart. However, the Olympica Fossae are somewhat different. They are oriented at an angle to the other Fissures suggesting that some other process was important in their formation.
A close-up image reveals that erosion by one or more catastrophic floods may have played a key role.
The teardrop shaped islands and the parallel ridges are rock left standing after the flood erosion. However, the deepest depression running basically East-West through the middle of the image was probably caused by tectonic extension, not flood erosion. This juxtaposition of tectonic and flood-carved valleys is visible elsewhere on Mars, suggesting that it may be common for the tectonic fracturing to release copious volumes of subterranean water.MareKromium
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ESP_012271_0940_RED_abrowse.jpgSouth Polar "Swiss-Cheese Surface Features" (Natural Colors; credits: Lunar Explorer Italia)53 visiteThis image represents a Martian Terrain containing "Swiss Cheese" features. This Terrain is found only within the residue of the Southern Polar Cap, which comprises of mostly frozen CO2 and H2O.
These particular features are flat-floored, circular depressions that are believed to form from different rates in the seasonal changes of the CO2 and H2O ices. Varying rates in sublimation (when these ices change directly to vapors upon heat and back to deposited solids upon cooling) produces these rimmed depressions from the flat polar ice plane. It is hypothesized that the depression areas are made up of dry ice - such as Carbon Dioxide - and the material below consists of the water ice.
This Carbon Dioxide solid rises and slightly evaporates into the thin Atmosphere in the Summer while the water layer remains in place. As the South Pole cools with seasonal change, the "Swiss Cheese" formation is obtained with risen CO2 rimmed depressions and flat water mesas.
The Martian North Pole will evaporate all of its CO2 in the Summer; however the South Pole is colder and this may explain why this Terrain is only found in this area.
Some of the circular features in the full image show distinct cusps that point in the direction of the Pole. These cusps suggest insolation, a measure of solar radiation that is pushing the movement/formation of these depressions away from the Pole. There is also an observed lateral outward growth of the features at the rate of about 1-to-3 meters a year, indicating to scientists that the depressions must form in a CO2 medium.MareKromium
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ESP_012302_0985_RED_abrowse.jpgCryptic Region Type "B" (Natural Colors; credits: Lunar Explorer Italia)53 visitenessun commentoMareKromium
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ESP_012425_1455_RED_abrowse.jpgUnusually-looking "Circular Surface Feature" (possible True Colors; credits: Dr G. Barca)53 visiteThis circular feature is a collection of hills, with some connected by ridges. The circularity suggests that perhaps there was once an impact crater here that was subsequently filled with material which was somehow more resistant to erosion than the landscape around it. Over time, as erosion stripped away the ground, the fill material was left standing higher (although it has clearly been eroded as well).
Nota Lunexit: si tratta di un "Exhumed Crater", ossìa di un cratere prima ricoperto da detriti e sedimenti e poi, a seguito di azioni prevalentemente eoliche (un vero e proprio scorticamento del suolo), è stato riportato - parzialmente - alla luce. Lo scorticamento che evidenzia il cratere sepolto è indice del fatto che i materiali i quali lo avevano ricoperto erano più resistenti e stabili dei materiali che circondano il cratere stesse (i quali, appunto, sono stati smossi dai venti). Un fenomeno similare, ma relativo ai canali, dà luogo ai cosiddetti "Inverted Channels", di cui si è già parlato in passatoMareKromium
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