| Ultimi arrivi - A Tribute To Mars Global Surveyor |
Phobos_from_MGS-004.jpgPhobos from Mars Global Surveyor (5)64 visitenessun commentoOtt 16, 2006
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Dunes-S2200554sub-00.jpgMigrating Dunes (Original NASA/MGS/MSSS b/w Frame)113 visiteCaption NASA originale:"This MGS-MOC image shows a suite of dunes in one of the several North Polar Dune Fields. The bright surfaces adjacent to some of the dunes are patches of frost. These dunes spend much of the Autumn, Winter, and Spring seasons covered with CO2 frost. Only in late Spring and in Summer are the dark windblown sands fully exposed.
Over the course of the 9+ years of the MGS mission, the MOC team has sought evidence that sand dunes may be migrating downwind over time. However, no clear examples of the movement of a whole dune have been identified. On Earth, such movement is typically detectable in air photos of the smallest active dunes over periods of a few years. Owing to the fact that the North Polar Dunes spend much of each Martian Year under a cover of frost, perhaps these move much more slowly than their frost-free, terrestrial counterparts. The sand may also be somewhat cemented by ice or minerals, likewise preventing vigorous dune migration in the present environment.
This view covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left. The dunes are located near 79.8°N, 127.1°W, and the picture was acquired on 11 September 2006.
Ott 11, 2006
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Craters-Unnamed_Crater-North_Polar_Regions-MGS-1.jpgUnnamed Crater in the Northern Plains (Original NASA/MGS/MSSS b/w Frame)55 visitenessun commentoOtt 04, 2006
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Craters-Unnamed_Crater_with_Gullies-MGS-0.jpgUnnamed Crater with Gullies (Original NASA/MGS/MSSS b/w Frame)60 visiteCaption NASA originale:"This MGS-MOC image shows gullies and cracked and stressed gully apron deposits in a South mid-Latitude crater. Gullies can also be seen in the deep shadow on the North wall of the crater. These gullies might have formed by the erosive action of liquid water, sometime in the not-too-distant martian past".
Location near: 36,7° South; 206,2° West
Image width: ~3 Km (~1,9 mi)
Illumination from: upper left
Season: Southern Autumn
Nota: attenzione a quello che la NASA ha scritto in sede di commento: adesso il passato al quale fare riferimento per pensare ad acqua che scorre "allo stato liquido" su Marte non è più remoto (un miliardo di anni o giù di lì); adesso questo passato è "...not too distant..." e cioè "passato prossimo". RicordateVi, in futuro, di quello che stiamo scrivendo da mesi: un frame dopo l'altro ed una parola dopo l'altra, la NASA si sta (lentamente ma) costantemente ridefinendo in chiave possibilista molte delle proprie posizioni (da anni più che consolidate) su molti aspetti/enigmi del Pianeta Rosso.
A quando l'ammissione di una "forma vitale" attuale, magari sotterranea?!?...Set 29, 2006
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North_Polar_Features-Unconformities-01.jpgNorth Polar "Unconformities" (Original NASA/MGS/MSSS b/w Frame)55 visiteCaption NASA originale:"This MGS-MOC image shows Layers exposed in the North Polar Region of Mars. The North Polar Cap is underlain by a thick sequence of Layered Material. The Layers are most commonly exposed on the slopes of troughs that are believed to have formed by Wind Erosion. The Layers give a banded appearance. In this example, some of the Layers are cut off (truncated) by other Layers. This truncation is a classic, textbook example of an Erosional Unconformity, a term commonly used by geologists. The Unconformity occurs when deposition of new layered material stops for a while and erosion occurs. Then, new layers form on top of the eroded surface and the older layers, at some point in time when the erosion stops and deposition of layered material resumes".
Location near: 78,6° North Lat. and 342,0° West Long.
Image width: ~3 Km (~1,9 mi)
Illumination from: upper right
Season: Northern SpringSet 28, 2006
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North_Polar_Regions-Frozen_Dunes-MGS-01.jpgPolar Dunes and Ice (False Colors; credits: NASA)90 visitenessun commentoSet 28, 2006
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North_Polar_Regions-Frozen_Dunes-MGS-00.jpgPolar Dunes and Ice (False Colors; credits: NASA)93 visitenessun commentoSet 28, 2006
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Aeolian_Features-Yardangs-Terra_Sabaea-MGS-02.jpgYardangs in Terra Sabaea (3 - Original NASA/MGS/MSSS b/w Frame)57 visiteLocation near: 1,4° North Lat. and 333,9° West Long.
Image width: ~3 Km (~1,9 mi)
Illumination from: upper left
Season: Northern SpringSet 24, 2006
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Aeolian_Features-Yardangs-Terra_Sabaea-MGS-01.jpgYardangs in Terra Sabaea (2 - Original NASA/MGS/MSSS b/w Frame)58 visiteLocation near: 1,4° North Lat. and 333,9° West Long.
Image width: ~3 Km (~1,9 mi)
Illumination from: upper left
Season: Northern SpringSet 24, 2006
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Aeolian_Features-Yardangs-Terra_Sabaea-MGS-00.jpgYardangs in Terra Sabaea (1 - Original NASA/MGS/MSSS b/w Frame)56 visiteCaption NASA originale:"This MGS-MOC image shows the contact between a group of Yardangs, tapered Ridges formed by the removal of relatively easily-eroded material (e.g.: Sedimentary Rock) and a concentration of dark-toned windblown Sand on the Floor of an Unnamed Crater in the Terra Sabaea Region of Mars".
Location near: 1,4° North Lat. and 333,9° West Long.
Image width: ~3 Km (~1,9 mi)
Illumination from: upper left
Season: Northern SpringSet 24, 2006
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Landslides-Tithonium_Chasma-MGS-01.jpgLandslide in Tithonium Chasma (2 - Original NASA/MGS/MSSS b/w Frame)55 visitenessun commentoSet 15, 2006
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Landslides-Tithonium_Chasma-MGS-00.jpgLandslide in Tithonium Chasma (1 - Original NASA/MGS/MSSS b/w Frame)56 visiteCaption NASA originale:"This MGS-MOC image shows a landslide that occurred off of a steep slope in Tithonium Chasma, part of the vast Valles Marineris Trough System".
Location near: 4,8° South Lat. and 84,6° West Long.
Image width: ~3 Km (~1,9 mi)
Illumination from: upper left
Season: Southern AutumnSet 15, 2006
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