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| Risultati della ricerca nelle immagini - "Undae" |
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
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North_Polar_Regions-Aspledon_Undae-PIA18237-PCF-LXTT-IPF.jpgAspledon Undae (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)113 visiteIn this VIS image, taken by the NASA - Mars Odyssey Orbiter on February, 27th, 2014, and during its 54.150th orbit around the Red Planet, we can see a small portion of a Martian Region known as Aspledon Undae: one of the several large Dunefields located near the North Pole of Mars. The term Undae, as you can easily understand, comes from the Latin word "Unda" (---> Wave; plural Undae ---> Waves) and, in this specific case, as the image suggests quite clearly, means Dunes (better yet: Wave-shaped Dunes).
Latitude (centered): 72,4562° North
Longitude (centered): 307,9130° East
Instrument: VIS
This image (which is a crop taken from an Original Mars Odyssey Orbiter b/w and Map-Projected frame published on the NASA - Planetary Photojournal with the ID n. PIA 18237) has been additionally processed, magnified to aid the visibility of the details, contrast enhanced, Gamma corrected and then colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Mars Odyssey 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_Regions-Olympia_Undae-PIA06848-00.jpgNorth Polar Erg: Olympia Undae (Original NASA/JPL/ASU b/w Frame)83 visiteImage information: VIS instrument;
Latitude: 81,4° North;
Longitude: 180,6° East (such as 179,4° West);
Resolution: 19 meter/pixel.
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North_Polar_Regions-Olympia_Undae-PIA06848-01.jpgNorth Polar Erg: Olympia Undae (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)170 visiteImage information: VIS instrument;
Latitude: 81,4° North;
Longitude: 180,6° East (such as 179,4° West);
Resolution: 19 meter/pixel.
MareKromium
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North_Polar_Regions-Olympia_Undae-PIA16320-PCF-LXTT-IPF.jpgFeatures of Olympia Undae (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)88 visiteThis NASA - Mars Odyssey Orbiter "VIS" image shows a portion of Olympia Undae, the largest Dunefield near the North Polar Cap. In this Region, the Dunes are spaced far enough apart so to allow us to see the details of the Surface that they are moving across.
Orbit Number: 47095
Latitude: 79,6934° North
Longitude: 149,575° East
Instrument: VIS
Captured: July, 26, 2012MareKromium
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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)64 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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PSP_001736_2605_RED_abrowse.jpgOlympia Undae (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)70 visiteThis observation shows Dark Dunes and light Polygonal Terrain in Olympia Undae, also known as the North Polar Erg.
Two sets of Dunes are obvious. The major set trends North-South, indicating winds from the East or West. Between the crests of these Dunes is a second set oriented mostly East-West.
Zooming in on the Dunes, a rippled texture is apparent, probably due to redistribution of sand at the scale of meters and less. Near the crests of some Dunes are Channel-like features, with some branching downslope. The origin of these Channels is unknown, but they may result from the flow and displacement of sand that was fluidized by sublimating CO2 or water frost.
Bright patches of ground are found in some inter-dune areas, with many having a polygonal texture.
Polygons on Earth form from contraction induced by stresses from dehydration, cooling and other processes, so these features may have a similar origin. The CRISM instrument on MRO and OMEGA on Mars Express indicates that many dunes in Olympia Undae are rich in the mineral Gypsum (---> gesso).MareKromium
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PSP_010219_2785_RED_abrowse-00.jpgDunes in Abalos Undae (ctx frame - possible True Colors; credits: Lunexit)55 visiteThe Abalos Undae Dunefield stretches westward, away from a portion (Abalos Colles) of the ice-rich North Polar Layered Deposits that is separated from the main Planum Boreum dome by two large chasms (---> abissi, crepacci).
These dunes are special because their sands may have been derived from erosion of the Rupes Tenuis unit (the lowest stratigraphic unit in Planum Boreum, beneath the icier layers) during formation of the chasms.
Some researchers have argued that these chasms were formed partially by melting of the polar ice.MareKromium
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PSP_010219_2785_RED_abrowse-01.jpgDunes in Abalos Undae (edm - possible True Colors; credits: Lunexit)55 visiteThis enhanced-color close-up (1,2 Km across) shows an example of dunes in Abalos Undae.
The enhanced color data illuminate differences in composition: the dunes appear of a green/bluish color because of their basaltic composition, while the reddish-white areas are probably covered in dust and residual ice. Upon close inspection, tiny ripples and grooves are visible on the surface of the dunes (both ripples and grooves are formed by wind action, as are the dunes themselves).
It is possible that these dunes are no longer migrating (the process of dune formation forces dunes to move in the direction of the main winds) and that the tiny ripples are the only active parts of the dunes today.MareKromium
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PSP_010501_2615_RED_abrowse.jpgAbalos Undae (Natural Colors; credits: Lunar Explorer Italia)66 visiteMars Local Time: 14:25 (early afternoon)
Coord. (centered): 81,6° North Lat. and 279,6° East Long.
Spacecraft altitude: 318,7 Km (such as about 199,2 miles)
Original image scale range: 63,8 cm/pixel (with 1 x 1 binning) so objects ~ 1,91 mt across are resolved
Map projected scale: 50 cm/pixel
Map projection: EQUIRECTANGULAR
Emission Angle: 0,1°
Phase Angle: 69,6°
Solar Incidence Angle: 70° (meaning that the Sun is about 20° above the Local Horizon)
Solar Longitude: 145,8° (Northern Summer)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer ItaliaMareKromium
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Psp_001736_2605_red.jpgThe Dunes of Olympia Undae (MULTISPECTRUM; credits: Lunexit)54 visiteThis HiRISE image shows dark dunes and light polygonal terrain in Olympia Undae, also known as the North Polar Erg.
Two sets of dunes are obvious. The major set trends ~North-South, indicating winds from the East or West. Between the crests of these dunes is a second set oriented mostly East-West.
Zooming in on the dunes, a rippled texture is apparent, probably due to redistribution of sand at the scale of meters and less. Near the crests of some dunes are channel-like features, with some branching downslope.
The origin of these channels is unknown, but they may result from the flow and displacement of sand that was fluidized by sublimating CO2 or water frost.
Bright patches of ground are found in some inter-dune areas, with many having a polygonal texture. Polygons on Earth form from contraction induced by stresses from dehydration, cooling, and other processes, so these features may have a similar origin.
The CRISM instrument on MRO and OMEGA on Mars Express indicates that many dunes in Olympia Undae are rich in the mineral gypsum. MareKromium
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R-PIA08788-1.jpgOlympia Undae (1)55 visiteThe Compact Reconnaissance Imaging Spectrometer for Mars, a mineral mapping instrument on NASA's Mars Reconnaissance Orbiter (CRISM), began observing Mars after its lens cover was opened on Sept. 27, 2006.
This image shows one of the first regions of Mars measured after CRISM's cover was opened.
CRISM takes images in two basic formats. The first format is a "targeted image" about 10 by 10 Km (about 6 by 6 miles), at about 18 mt (60 feet) per pixel, in 544 colors covering wavelengths of 0,36 to 3,92 micrometers. The second format is a lower-resolution strip 10 Km (about 6 miles) wide and thousands of kilometers long, at 200 mt (660 feet) per pixel, in 72 colors. Many thousands of these "multispectral survey" strips are used to build a global map.
The image is part of the second multispectral survey strip, taken at 22:36 UTC (6:36 p.m. EDT) on Sept. 27, 2006. Only minimal processing of the data has been done at this early point in the MRO's Mission.
The strip crosses part of the north polar region named Olympia Undae, and stretches between 76.7 north latitude, 141.9 east longitude and 85.5 north, 115.8 east. From the top, the northern end of the image crosses layers of dusty and clean ice in the north polar cap. Moving south the image covers dusty sedimentary deposits, dark sand dunes, and outlying polar ice deposits.
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