| Piú votate - Mars Reconnaissance Orbiter (MRO) |
PSP_002244_1720_RED_abrowse.jpgWhite Rock (Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis image shows a portion of a relatively bright landform named "White Rock" on the Floor of Pollack Crater, in the Sinus Sabaeus Region of Mars.
Data from the Mars Global Surveyor Thermal Emission Spectrometer (TES) indicates that this landform is not anomalously bright, relative to other bright Martian Regions. Further, the apparent brightness seen here is due to contrast with other materials on the Crater Floor.
Dunes and Ripples are visible in the dark material between the bright ridges. Their orientations appear to be influenced by wind directionally channeled by the ridges.
Material appears to have been shed from the white landform and deposited on the darker bedforms indicating that the light-toned outcrops break down into fine materials.
Its high albedo and location in a topographic basin have led to suggestions that White Rock is an erosional remnant of an ancient lacustrine evaporate deposit. Other interpretations include an eroded accumulation of compacted or weakly cemented aeolian sediment.MareKromium
(5 voti)
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SPLD-PIA13269-PCF-LXTT3.jpgSouth Polar Layered Deposits and Residual Cap (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis image from NASA's Mars Reconnaissance Orbiter (MRO) shows a variety of surface textures within the South Polar Residual Cap of Mars.
It was taken during the Southern Spring, when the Surface was covered by seasonal CO2 Frost, so that Surface relief is easily seen. Illumination is from the bottom left, highlighting long Troughs at to the right and round pits and irregular Mesas to the left of center.
These unique landforms are common in the South Polar Residual Cap, which is known from previous Mars Global Surveyor images to be eroding rapidly in places. Right of center, SPLDs are exposed on a Sun-facing Scarp. These Deposits are older than the Residual Ice Cap, and the Layers are thought to record climate variations on Mars similar to ice ages on Earth.MareKromium
(5 voti)
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Dunes-PIA13268-PCF-LXTT.jpgDunes in Richardson Crater (EDM - Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)56 visiteThis observation from NASA's Mars Reconnaissance Orbiter (MRO) is a view of the Sand Dunefield in Richardson Crater, still partually covered with seasonal frost.
This EDM is a close-up view of defrosting patterns on the Dunes. The frost is a combination of frozen CO2 and some water ice that covers the Dunes in the Winter and Spring. As the seasonal frost sublimes away, odd features such as spots, fans, and streaks form.
Small dark streaks on the dune slip-face slopes may be where recent avalanches of sand, or perhaps wind, has moved the dark sand underlying the frost, or where frost has been removed to expose the sand. Alternatively, the dark streaks may be patches of coarse-grained ice that are clear enough so that the dark material below the ice is visible.
The slip-faces indicate the general direction of sand transport.
It has been hypothesized that the Dark Spots and Fans may be "geysers" or "cold gas jets" that form when sublimation processes trap gas at the bottom of the ice. The gas is released through cracks in the ice, entraining dust from below the ice and scattering it onto the Surface to form the Dark Spots and Fans.MareKromium
(5 voti)
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ESP_018011_2565_RED_abrowse.jpgBetween Abalos and Olympia Undae... (Absolute Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis HiRISE image shows some large Sand Dunes near the North Pole of Mars. The picture was taken in summertime, with only small patches of ice remaining on the Surface: this show up as bright, somewhat blue, spots on slopes that provide some shading from the Sun.
Geologists would classify these Dunes as "sand-starved" because the ground between the Dunes has almost no sand; in addition, this ground shows a pattern of cracks that is typical of icy permafrost undergoing through seasonal expansion and contraction.
It is also possible that some Subsurface Ice exists inside the Dunes themselves; if so, the Dunes are not currently moving, and the ice is acting as a "stabilizer".
This idea is supported by the observation that there are small Landslide Gullies being cut into the Dunes, something not seen if the Dunes are rejuvenated as they move in the wind. However, to test this idea this area has been repeatedly imaged by multiple cameras on different spacecrafts.
With meticulous care it will be eventually possible to determine just how much the Dunes have moved or changed over the past years.MareKromium
(5 voti)
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ESP_017888_1950_RED_abrowse.jpgOlympus' Lava Flows (Extremely Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visiteThe flanks of Olympus Mons are covered with Lava Flows (one on top of the other) Most of these Flows are relatively narrow, with a channel running down the middle. They appear similar to the Lava Flows found on Mt. Etna in Sicily (Italy).
However, in this image, we see these typical Flows partially covered by another, more recent one. This last one also shows a Central Channel, and it is about 10 times wider than the more typical Lava Flows. At the center of the HiRISE image the Channel disappears.
This is probably because the Channel was blocked here and Lava spilled out of it and covered a broad, fan-shaped, area. The eruption that produced this unusual flow was probably more vigorous and perhaps lasted longer than the more common ones.MareKromium
(5 voti)
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Deuteronilus_Mensae-PIA12996.jpgDeuteronilus Mensae (Natural Colors; credits for the add. process, and color.: Dr Paolo C. Fienga - Lunexit Team)80 visiteThe Terrain in this image lies in the Deuteronilus Mensae Region, along the highland-lowland Dichotomy Boundary in the Northern Hemisphere of Mars.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter recorded this image on March 9, 2010.
The target for this HiRISE observation was a suggestion submitted through the camera team's HiWish public-suggestion program. For more information about how to submit target suggestions, see http://uahirise.org/hiwish/.
This Region contains many Mesas surrounded by Lobate Debris Aprons that are thought to be ice-rich. These Aprons have been interpreted as a variety of possible features including rock glaciers, ice-rich mass movements, or debris-covered glacial flows. Recent radar data from the Shallow Radar instrument on the Mars Reconnaissance Orbiter has shown them to be composed of nearly pure ice. This image shows an area at the edge of one of these Mesas with a Lobate Debris Apron extending from its base.
Both the Mesa top and the Surface of the Debris Apron appear covered with ice-rich mantling materials characteristic of the Martian Mid-Latitudes and thought to have been deposited around 10 million years ago during a period of high obliquity.
This image covers a swath of ground about 1 Km (about two-thirds of a mile) wide. It is a portion of HiRISE observation ESP_016959_2240, which is centered at 43,62° North Latitude and 28,62° East Longitude. The season on Mars is Northern-Hemisphere Spring. MareKromium
(5 voti)
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Vastitas_Borealis-DD-PIA12876.jpgCaught in the Act (Natural Colors; credits: NASA/JPL-Caltech/University of Arizona - Additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)73 visiteThis image was targeted to study Knobs in Mars' Northern Plains (Vastitas Borealis), just North of Scandia Crater. What surprised scientists was the presence of a Dust Devil passing by.
As on Earth, Dust Devils form when ground heated by sunlight warms the air above it. The hot air rises, forming an updraft accompanied by vortical motions.
Because warm ground is a requirement, Dust Devils on Mars generally form in late Spring to Summer, especially at high Latitudes.
This image was taken in early Spring (2010), at a latitude of about 61° North. No Dust Devil has been seen this far from the Equator at such an early season before.MareKromium
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ESP_016032_2600_RED_abrowse-02.jpgNorthern Spring (EDM - Natural Colors; credits: NASA/JPL/Univ. of Arizona)55 visitenessun commentoMareKromium
(5 voti)
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Gullies-Terra_Sirenum-PIA12881.jpgGullies in Terra Sirenum (credits: NASA/JPL-Caltech/University of Arizona)55 visiteThis observation shows part of an Unnamed Crater, located inside the much larger Newton Basin, in the Terra Sirenum Region of Mars.
This Unnamed Crater is approx. 7 Km in diameter (over 4 miles) and some 700 meters (760 yards) deep.
Numerous Gully Systems are visible on the East- and South-facing Walls of the Crater; their characteristics are astonishingly diverse.
This EDM covers an area of nearly 610 x 740 meters (670 x 800 yards). North is up; illumination is from the North-West.
This EDM depicts several Gullies carved in the South-West-facing Wall of the Crater.
These troughs are extremely rectilinear, lack tributaries, and do not seem to have Terminal Fan Deposits: they terminate rather abruptly, some of them in a spatula-like shape.
Their characteristics contrast sharply with those of other Gully Systems located elsewhere in this same Crater, which are sinuous, have numerous tributaries, and show distinct Fan Deposits.MareKromium
(5 voti)
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Gale_Crater-PIA12508.jpgLayers in lower formation of Gale Crater Mound (Natural Colors; credits NASA/Dr Paolo C. Fienga - Lunexit Team)111 visiteLayers of rock exposed in the lower portion of a tall Mound near the center of Gale Crater on Mars exhibit variations in layer thickness and range between dark and light tones. The Crater's Mound of layered material is over 4 Km (approx. 2,4 miles) high, making it more than twice as thick as the stack of rocks exposed in the Grand Canyon on Earth.
Gale Crater is approx. 152 Km (about 94 miles) in diameter.
This view of layering in the Mound's lower formation covers an area about 950 meters (3100 feet) wide. It was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on April 23, 2009.
Observations of the lower formation by the Compact Reconnaissance Imaging Spectrometer for Mars, on the same orbiter, have indicated the presence of Sulfate Salts and clay minerals in these rock layers. The changes in composition from the lower (older) to the upper (younger) layers in the Gale Crater Mound may record stages in water loss and the drying out of Mars.
This image is one product from HiRISE observation ESP_012841_1750, centered at 4,9° South Lat., 137,2° East Long.MareKromium
(5 voti)
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PSP_001808_1875_RED_abrowse-01.jpgSlope Streaks in Terra Sabaea (EDM - Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis EDM is a close-up view of the Crater Rim revealing dark and light-toned Slope Streaks. Slope Streaks' formation is among the few known processes currently active on Mars. While their mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material.
Other ideas include the triggering of Slope Streaks' formation by possible concentrations of near-Surface ice or scouring of the Surface by running water from aquifers intercepting slope faces, Spring Discharge (perhaps brines) and/or hydrothermal activity.
Several of the Slope Streaks seen here, particularly the 3 longest darker Streaks, show evidence that downslope movement is being diverted around obstacles such as large boulders. Several Streaks also appear to originate at boulders or clumps of rocky material.
In general, the Slope Streaks do not have large deposits of displaced material at their downslope ends and do not run out onto the Crater Floor suggesting that they have little reserve kinetic energy. The darkest Slope Streaks are the youngest and can be seen to cross cut and superpose older and lighter-toned Streaks.
The lighter-toned streaks are believed to be dark streaks that have lightened with time as new dust is deposited on their surface.MareKromium
(5 voti)
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PSP_001700_2505_RED_abrowse-01.jpgThe "Frozen pseudo-Lake" of Vastitas Borealis (EDM - Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)61 visiteLa parte realmente "interessante" del frame è proprio nella texture della porzione più chiara e profonda del "Frost Patch", perchè è in quel punto della Surface Feature che, volendo, si riesce a vedere qualcosa di significativo e quindi si può anche provare a ragionare e ad osservare con estrema attenzione eppure...eppure la NASA ci mostra le dunette (fangose?) che lo delimitano ed ignora il resto.
Beh, vorrà dire che l'Analisi sulla porzione più "bianca e profonda" del Frost Patch la faremo noi, con calma.
E che i Signori di Pasadena ci scusino tanto per aver osato dubitare della correttezza del loro (pseudo) "Metodo Scientifico"!MareKromium
(5 voti)
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