Mars Reconnaissance Orbiter (MRO)
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North_Polar_Layered_Deposits-PIA01925.jpgNorth Polar Layers66 visiteCaption NASA originale:"This view shows the basal layers of Mars' north polar layered deposits. The floor of Chasma Boreale is at the bottom of the image. This is a sub-image of a larger view imaged by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter on Oct. 1, 2006. The resolution is 64 cm (about 25") per pixel, and the scene is 568 mt (approx. 621 yards) wide".
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North_Polar_Layered_Deposits-PIA12997.jpgNorth Polar Layered Deposits (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)66 visiteThe Martian North Polar Layered Deposits (NPLD) are an ice sheet much like the Greenland ice sheet on the Earth. Just as with the ice sheet in Greenland this Martian ice sheet contains many layers that record variations in the Martian Climate. Sometimes icy layers can be ablated away during warm climates. Later the ice sheet can be buried by new ice layers and grow in size again. It's likely that many of these cycles have occurred over the ice sheet's history.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter recorded this image of NPLD on March 11, 2010. The target for this observation was a suggestion submitted by Greg Clements through the camera team's HiWish public-suggestion program. For more information about how to submit target suggestions, see http://uahirise.org/hiwish/.
Fluctuations in the thickness of the ice sheet are most pronounced at the edges of the sheet, where this HiRISE image was taken. The ice sheet ends here in a gentle scarp that slopes about 8° downhill from bottom to top in this image. The layering within the ice is exposed on this Sloping Surface. The thickness of the ice here is about 1 Km (approx. 3300 feet). Scientists are analyzing these layers to see what information they might hold regarding previous Martian Climates.
This image covers a swath of ground about 1 Km (approx. two-thirds of a mile) wide.
It is a portion of HiRISE observation ESP_016973_2595, which is centered at 79,30° North Latitude and 351,46° East Longitude.
The season on Mars is Northern-Hemisphere Spring.MareKromium
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North_Polar_Layers-PSP_001332_2620_RED.jpgUnconformity in the North Polar Layered Deposits (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)65 visitenessun commentoMareKromium
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North_Polar_Layers-PSP_001334_2645_RED.jpgIcy North Polar Layers (natural colors)58 visitenessun commentoMareKromium
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North_Polar_Layers-Tra_000825_2665_red.jpgNorth Polar Layered Deposits (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team:)65 visitenessun commentoMareKromium
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North_Polar_Regions-Chasma_Boreale-PIA01926-det.jpgThe Walls of Chasma Boreale78 visiteThe Martian terrain in this remarkable image is at the head of a large chasm, named Chasma Boreale, which cuts through Mars' North Polar Layered Deposits (MNPLD). These ice-rich layered deposits are about 3000 mt (about 9.800 feet) thick and 1000 Km (1.600 miles) across, much like the Greenland ice-sheet on Earth. The head of Chasma Boreale ends in a steep icy cliff more than 1000 mt (about 3300 feet) high. The cliff has both light- and dark-toned layers, seen at right in this image. The image was taken by the HiRISE camera on NASA's MRO. The internal layers of the ice-sheet are visible in the cliff walls. The dark-toned flat area in the center and left of the image is the floor of this chasm, which contains many craters.
Scientists have proposed that Chasma Boreale was formed by a catastrophic flood that began under the ice-sheet and was later widened by wind erosion. However, the large number of craters on the chasm's floor implies that the floor is much older than the ice sheet. These craters should have been removed by the suggested flood; their presence has caused some Mars researchers to instead speculate that no large flood occurred and that Chasma Boreale was not covered with very much ice.
In addition to layered ice, there is also some material within the north polar layered deposits that appears to be composed of sand. The dark material near the base of the cliff wall is thought to be aprons of debris being eroded from sand-rich layers. Zooming in on this dark material with HiRISE reveals ripples, which are diagnostic of moving sand.
Some bright spots of material visible on the cliff wall were not present in previous years. These are likely patches of water frost. Each year layers of carbon dioxide and water frost coat this terrain before being removed during the summer. The water frost lasts longer, and patches that are shaded by nearby steep topography (such as this one) can persist even into late summer.
An unexpected surprise, not visible with previous camera resolutions, is the fragmentation of the exposed surfaces of these icy layers into polygonal blocks. These blocks appear to be breaking away from the layer margins and forming boulder-sized debris, which then rolls down slope (a process called mass-wasting). These boulders are likely to be large blocks of dusty water ice; once separated from the main ice-sheet they can be eroded away by sunlight. More boulder-sized objects are visible out in the floor of the chasm. Polygons are also visible throughout the chasm floor, indicating that water-ice is just below the surface.
Image TRA_000845_2645 was taken by the HiRISE camera on Oct. 1, 2006. The complete image is centered at 84.6 degrees latitude, 3.4 degrees east longitude. The range to the target site was 316 kilometers (198 miles). At this distance the image scale is 63 centimeters (25 inches) per pixel (with 2 x 2 binning), so objects about 186 centimeters (73 inches) across are resolved. The image shown here has been map-projected to 50 centimeters (20 inches) per pixel. North is up. The image was taken at a local Mars time of 3:34 p.m. and the scene is illuminated from the west with a solar incidence angle of 62.3 degrees, thus the sun was about 27.7 degrees above the horizon. At a solar longitude of 114.3 degrees, the season on Mars is northern summer.
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North_Polar_Regions-Olympia_Undae-PIA18243-PCF-LXTT-IPF.jpgOlympia Undae (Absolute Natural Colors; credits for the additional process. and color. Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)61 visiteOlympia Undae is a large Field of Sand Dunes surrounding the North Polar Ice Cap of Mars. Because of the High Latitude of the Dunes, they are covered with Water and Carbon Dioxide (CO2) Frost for the whole Winter, Springtime and part of Summer as well (remember that during the Wintertime the Dunes are also poorly illuminated). Said that, it comes natural to understand that these Dunes are are best viewed during Summertime (from mid, to late Summer, to be more precise), when some of their most obvious Features - such as the Ripples that form on the Dunes' Surface - can be seen in detail.
In this sub-image, taken by the NASA - Mars Reconnaissance Orbiter on April, 9, 2014, we can see the Dunes in the Early Martian Summer. The Dark (Gray, with Reddish nuances here) Material visible here is the Sand that makes up the Dunes. Between them, Bright Bedrock as well as some lingering Patches of Frost (White-colored) that has not yet sublimated, are also well visible. If you look carefully, you will be able to see small Ripples that formed on the Dunes' Flat Surfaces, as well as Bright so-called "Inter-Dune Areas".
This specific area has been viewed several times by HiRISE, so NASA was able to compare this image to other past ones (from about 2 years ago); the most obvious difference between these images was simply found in the Illumination, which was much better in the AD 2012 (it is possible to say so once it has been noticed that the 2012 images showed much finer details). However, and despite that beforementioned difference, several changes in the Boundaries of the Sand and Ripple positions were also found, and this last circumstance showed - and proved - that (the Dominant and very strong North Polar) Winds, perhaps assisted by the Sublimation of the Frost that covers most of the Dunes (an event, the latter, that actually contributes in loosening Sand), are continuously modifying the Landforms of Olympia Undae, from one year to another.
Mars Local Time: 13:52 (Early Afternoon)
Coord. (centered): 81,633° North Lat. and 178,830° East Long.
Spacecraft altitude: 321,8 Km (such as about 199,837 miles)
Original image scale range: 32,2 cm/pixel (with 1 x 1 binning) so objects ~ 97 cm across are resolved
Map projected scale: 25 cm/pixel
Map projection: POLAR STEREOGRAPHIC
Emission Angle: 17,9°
Phase Angle: 8,0°
Solar Incidence Angle: 60° (meaning that the Sun was about 30° above the Local Horizon at the time the picture was taken)
Solar Longitude: 113,9° (Northern Summer - Southern Winter)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer Italia
This picture (which is a NASA - Original Mars Reconnaissance Orbiter False Colors and NON Map-Projected sub-frame identified by the serial n. ESP_036099_2615-1) has been additionally processed, magnified to aid the visibility of the details, contrast enhanced, Gamma corrected, and then re-colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Mars Reconnaissance Orbiter and then looked down, towards the Surface of Mars), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.MareKromium
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North_Polar_Scarp-Psp_001341_2650_red.jpgNorth Polar Scarp53 visitenessun commentoMareKromium
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NorthernLayers-TRA_000878_2660_RED.jpgNorth Polar Layered Deposits (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team:)58 visitenessun commentoMareKromium
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Northern_Dunes-PIA13797-1.jpgSeasonal Changes in a Dune of the North Polar Erg54 visiteThree images of the same location taken at different times on Mars show seasonal activity causing Sand Avalanches and Ripple changes on a Martian Dune. Time sequence of the images progresses from top to bottom. Each image covers an area of 285 meters (312 yards) by 140 meters (153 yards). The Crest of a Dune curves across the upper and left portions of the image.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took these images. The site is at about 84° North Latitude and 233° East Longitude, in a vast Region of Dunes at the Edge of Mars' North Polar Ice Cap. The area is covered by Carbon-Dioxide (CO2) Ice in Winter but is Ice-free in Summer. The top and bottom images show part of one Dune about one Mars Year apart, at a time of the year when all the Seasonal Ice has disappeared: in late Spring of one year (top) and early Summer of the following year (bottom). The middle image is from the second year's mid-Spring, when the Region was still covered by Seasonal CO2 Ice.
Spring evaporation of the Seasonal Layer of Ice is manifested as Dark Streaks of fine particles carried to the top of the Ice Layer by escaping gas. The bottom of the Ice Layer, in contact with the Dark Ground, warms faster than the top of the Ice does in the Spring. Carbon-Dioxide gas produced by the thawing (----> disgelo) of the bottom Ice is temporarily trapped under the top Ice.
As the Ice evaporates from the bottom, flow of gas under the Ice destabilizes the Sand on the Dune, thus causing the Sand itself to avalanche down the Dune "Slipface".
A before-and-after comparison of the Dune shows new Alcoves and extension of the Debris Apron on the Slipface of the Dune caused by descending Grains of Sand. New Wind Ripples appear on the Debris Apron.
The top image is a portion of the HiRISE observation catalogued as PSP_008867_2640, taken on June 17, 2008.
The middle image is a portion of the HiRISE observation catalogued as ESP_016779_2640, taken on Feb. 23, 2010.
The bottom image is a portion of the HiRISE observation catalogued as ESP_018427_2640, taken on July 2, 2010.MareKromium
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Northern_Dunes-PIA13797-2-PCF-LXTT.jpgSeasonal Changes in a Dune of the North Polar Erg (Absolute Natural Colors; credits for the Additional Process. and Color.: Dr Paolo C. Fienga - Lunexit Team)73 visitenessun commentoMareKromium
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Northern_Plains-Psp_001380_2520_red-00.jpgAnother "Frozen Lake" in the Northern Plains? (1 - CTX Frame - False Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)55 visitenessun commentoMareKromium
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