Mars Reconnaissance Orbiter (MRO)
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PSP_003830_1740_RED_abrowse-02.jpgLayered Bedrock in Candor Chasma (EDM n.2 - Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)82 visitenessun commentoMareKromium
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PSP_003843_1680_RED_abrowse.jpgPossible MSL Landing Side in Eastern Melas Chasma (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)65 visitenessun commentoMareKromium
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PSP_003907_1780_RED_browse-1.jpgProposed MSL Site in Iani Chaos (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)58 visitenessun commentoMareKromium
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PSP_003921_1690_RED_browse-PCF-LXTT.jpgProposed MSL Landing Site in Eos Chasma (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team) 140 visitenessun commentoMareKromium
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PSP_003948_0935_RED_browse.jpgSouth Pole Residual Cap (Swiss-Cheese Terrain Monitoring)53 visiteLike Earth, Mars has concentrations of water ice at both Poles. Because Mars is so much colder however, Carbon Dioxide (CO2) ice is deposited at high latitudes in the Winter and is removed in the Spring, analogous to winter-time water ice/snow on Earth.
Around the South Pole there are areas of this CO2 ice that do not disappear every Spring, but rather survive Winter after Winter; this persistent CO2 ice is called the "South Pole Residual Cap".
The retention of CO2 ice throughout the year by the Southern Polar Cap is one characteristic that distinguishes it significantly from Mars' North Polar Cap.
As can be seen in this HiRISE image of the south pole residual cap, relatively high-standing smooth material is broken up by circular, oval, and blob-shaped depressions. This patterned terrain is called "swiss cheese" terrain. The high-standing areas are carbon dioxide ice with thicknesses of several to approximately 10 meters. The depressions are thought to be caused by the removal of this carbon dioxide ice by sublimation (the change of a material from solid directly to gas). As most depressions seem to have relatively flat floors, there is likely some layer below, possibly made of water ice, that cannot be as easily removed by sublimation. Complicated shapes arise when neighboring growing depressions intersect.
A previous Mars imaging system, the Mars Orbiter Camera (MOC), took images of the same places on the south pole residual cap every year for many years, and showed that there are annual changes taking place within it. By looking at different sizes and shapes of depressions in an image such as this, and by comparing images of the same place from year to year, the development of "swiss cheese" terrain can be described. The sublimation process may begin as a small, shallow depression in a smooth surface. This depression then deepens until reaching the resistant layer below, and continues to expand laterally in all directions, creating the generally round depressions we see today. Different heights and thicknesses of smooth areas, and different depths of depressions, may indicate that multiple episodes of accumulation and sublimation have occurred.
This is one of the locations previously monitored at lower resolution by MOC. With the high resolution and repeat-imaging capability of HiRISE, we intend to continue monitoring and better measure the amount of expansion of the depressions over one or more Mars years. This is one of the locations specifically targeted by HiRISE for this purpose.
Knowing the amount and rate of carbon dioxide removal can give us a better idea of the role of carbon dioxide (the main component of the Martian atmosphere) in polar and atmospheric processes, of current environmental and climatic conditions, and of how Mars climate may be changing.
In HiRISE images such as this one, it is evident on the slopes of the large, especially high mesa just above the center of the image that the carbon dioxide-rich material may be constructed of several individual horizontal layers. However, it also appears that as erosion eats into the mesa, pieces of a stronger mesa surface layer break off and are left strewn on the mesa slopes, where they may give the appearance of layering.
An interesting feature in this HiRISE image is the crisscrossing network of faint ridges and troughs on the upper smooth terrain. These may also be complexly involved in the sublimation and deposition of carbon dioxide ice. MareKromium
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PSP_003972_1305_RED_browse-PCF-LXTT.jpgProposed MSL Landing Site in an Unnamed Southern Crater (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team) 92 visitenessun commentoMareKromium
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PSP_004000_0945_RED_abrowse-00.jpgChangings... (CTX Frame - credits: NASA/JPL/University of Arizona)91 visiteHiRISE is monitoring the Residual Carbon Dioxide Cap on (or near) the South Pole of Mars to see how it changes over time.
Some of this Terrain contains many Pits, earning it the nickname "Swiss Cheese Terrain". One of our monitoring spots is over what looks like a deranged "Happy Face". If you look closely, you'll see many changes since the first HiRISE image, PSP_004000_0945, was acquired in 2007. The news is that the Pits have grown larger. When this Pit growth was first discovered, it was suggested to be an indication of climate change on Mars. However, we now suspect that the CO2 that sublimates from the Pit Walls recondenses on the nearby surfaces, so there is no net change in the total amount of frozen CO2.
Acquisition date: December, 30th, 2010
Mars Local Time (M.L.T.): 18:03 (Late Afternoon)
Latitude (centered): 85,7° South
Longitude (East): 6,5°
Spacecraft Altitude (or Range to Target Site): 247,6 km (154,8 miles)
Original image scale range: 24,8 cm/pixel (with 1 x 1 binning) so objects ~74 cm across are resolved
Map Projected Scale: 25 cm/pixel
Map Projection: POLAR STEREOGRAPHIC
Emission Angle: 0,2°
Phase Angle: 78,9°
Solar Incidence Angle: 79° (with the Sun about 11° above the Local Horizon)
Solar Longitude: 207,7° (Northern Autumn)MareKromium
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PSP_004000_0945_RED_abrowse-01.jpgChangings... (EDM - credits: NASA/JPL/University of Arizona)96 visitenessun commentoMareKromium
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PSP_004000_0945_RED_browse~0.jpgThe "South Polar Residual Cap" (natural colors; credits: Lunexit)53 visite
Like Earth, Mars has concentrations of water ice at both poles. Because Mars is so much colder, however, the seasonal ice that is deposited at high latitudes in the winter and is removed in the spring (generally analogous to winter time snow on Earth) is carbon dioxide ice. Around the south pole there are areas of this carbon dioxide ice that do not disappear every spring, but rather survive winter after winter&emdash;this persistent carbon dioxide ice is called the south pole residual cap.
Relatively high-standing smooth material is broken up by circular, oval, and blob-shaped depressions, forming a pattern called "swiss cheese" terrain. The high-standing areas are carbon dioxide ice with thicknesses probably of several meters. The depressions are thought to be caused by the removal of carbon dioxide ice by sublimation (the change of a material from solid directly to gas). By looking at different sized depressions in an image such as this, and by comparing images of the same place from year to year, the development of "swiss cheese" terrain can be observed.
The sublimation process may begin anywhere as a small depression. Once this small depression is formed, it expands laterally in all directions, creating the rounded depressions we see today. As most depressions seem to have a similar depth and have relatively flat bottoms, there is likely some layer below, possibly of water ice, that cannot be as easily removed by sublimation. Thus, while the south polar residual cap as a whole is present every year, there are certainly annual changes taking place within it.
Especially apparent and interesting in this image are the strips of material that parallel the edges of many depressions. Often there are two or more concentric strips that are smooth like the surrounding surface, but seem to be lower than the surrounding surface and in places appear to be tilted down towards the center of the depression. Inner strips are sometimes broken up into chunks. It may be that the uppermost smooth layer is a bit more resistant to sublimation than the material just below it&emdash;the quicker removal of the underlying material might cause the stronger upper layer to detach from the surrounding terrain and settle down towards the center of the depression.
Alternatively, these ringing strips may indicate that many layers are present within the carbon dioxide ice. Another interesting feature is the faint crisscrossing network of ridges on the upper smooth terrain. These may also be complexly involved in the sublimation and deposition of carbon dioxide ice.
With the high resolution capability of HiRISE, we intend to measure the amount of expansion of the depressions over one or more Mars years. Knowing the amount of carbon dioxide removed can give us an idea of the current atmospheric and climate conditions, and possibly how Mars climate may be changing.
MareKromium
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PSP_004000_1560_RED_browse.jpgLayers in Eberswalde Crater53 visiteThis image covers a portion of Eberswalde Crater, revealing a possible delta-lake transition. Water flowed into the crater through a series of tributary channels to the west of the crater and after the water entered, it formed a distributive network and partly filled the crater to form a lake (Eberswalde Crater is approx. 70 Km wide and 1,2 Km deep).
The bright layers are part of the terminal scarp at the eastern edge of the delta. Some of the steeper slopes visible at the edge of the fan may be coarser-grained resistant channel ridges. The CRISM instrument on board the Mars Reconnaissance Orbiter has detected phyllosilicates (clays) in the bright layers. One of the ways clays form on Earth is when water erodes rock and makes fine particles which settle out of water; this often occurs in river deltas and lake beds.
The delta in Eberswalde Crater and the detection of phyllosilicates provides evidence for possible persistent aqueous activity on Mars.MareKromium
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PSP_004006_1900_RED_abrowse-PCF-LXTT.jpgFissure in Cerberus Fossae (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)88 visitenessun commentoMareKromium
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PSP_004018_1505_RED_abrowse.jpgLayers in Columbus Crater (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)84 visiteThis HiRISE image shows bright Layers on the Floor of Columbus Crater, a large Impact Basin in the Southern Highlands of Mars.
The Crater is very old and has gone through much modification. Its Rim is relatively low and the Floor is flat, and it is likely that material has been eroded from the Rim and deposited on the Crater Floor.
The bright stripes that appear in this image at low resolution are likely Sedimentary Deposits. This bright material also includes dark patches which may be embedded within it, or the dark material could be covering the light one. The small-scale topography is rugged, likely an erosional characteristic of the dark material which covers much of the Surface.
Bright materials like those visible here are found in many places on Mars. In this case, it is likely that they are part of the Sediments that have filled the Basin, but it is not certain how they were deposited.
In many places, bright Sediments exhibit fine horizontal banding, suggesting that they were once part of more extensive, flat-lying Layers of rock. In the bright materials here, Layering is rare and the original geometry somewhat more obscure. Impact Craters in the scene have excavated the Dark Surface, but in several cases this has neither exposed layering nor bright material.MareKromium
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