| Ultimi arrivi - Mars Reconnaissance Orbiter (MRO) |
Kunowsky_Crater_-_Sand_Dunes-StripedDunes_HiRISE_1182.jpgStriped Sand Dunes126 visiteCaption NASA:"Why are these sand dunes on Mars striped?
No one is sure.
The featured image shows striped dunes in Kunowsky Crater on Mars, photographed recently with the Mars Reconnaissance Orbiter’s HiRISE Camera.
Many Martian dunes are known to be covered unevenly with carbon dioxide (dry ice) frost, creating patterns of light and dark areas. Carbon dioxide doesn’t melt, but sublimates, turning directly into a gas. Carbon dioxide is also a greenhouse material even as a solid, so it can trap heat under the ice and sublimate from the bottom up, causing geyser-like eruptions. During Martian spring, these eruptions can cause a pattern of dark defrosting spots, where the darker sand is exposed.
The featured image, though, was taken during Martian Autumn, when the weather is getting colder – making these stripes particularly puzzling. One hypothesis is that they are caused by cracks in the ice that form from weaker eruptions or thermal stress as part of the day-night cycle, but research continues.
Watching these dunes and others through more Martian seasons may give us more clues to solve this mystery".MareKromiumGen 08, 2021
|
|
ESP_022578_2030_and_ESP_014007_2030.jpgSand-Lakes (3D - Credits for the additional process.: Marco Faccin and Elisabetta Bonora)93 visitenessun commentoMareKromiumNov 06, 2020
|
|
PSP_003180_0945_RED_abrowse-03.jpgSouth Polar Dust Fans (Enhanced Natural Colors; Credits for the add. process. and color.: Dr Paolo C. Fienga)132 visitenessun commentoMareKromiumGen 06, 2020
|
|
PSP_20_008753_1876_XN_07N211W.jpgPyramid?173 visiteSu immagini come questa potremmo speculare per anni, senza arrivare a nulla (come ci insegna la - ormai - "antica" vicenda di Cydonia Mensae). Dunque la proponiamo così com'é (dettaglio magnificato di un frame MRO).
Interessante.... O no?!?MareKromiumDic 18, 2019
|
|
PIA23513-4.jpgFlying over Olympus & Friends... (S-EDM)203 visiteDust Storm? Smoke from a volcanic vent? That's the best we can offer you so far.... Then, You decide.MareKromiumDic 17, 2019
|
|
PIA23513-2.jpgFlying over Olympus & Friends... (EDM)203 visiteHo fatto un minimo di processing addizionale, magnificando ed esaltando contrasti e contorni. Immagine comunque splendida!MareKromiumDic 12, 2019
|
|
Remnants-ESP_038184_1815_40-1.jpgUnusually-looking Surface Features on Mars (EDM from ESP 038184-1815-40)179 visitenessun commentoMareKromiumDic 08, 2019
|
|
Ruins-ESP_038184_1815_57-1.jpgUnusually-looking Surface Features on Mars (EDM from ESP 038184-1815-57)150 visitenessun commentoMareKromiumDic 08, 2019
|
|
PIA23513-1000w.jpgFlying over Olympus & Friends...159 visitenessun commentoMareKromiumDic 08, 2019
|
|
Dust_Storm-MGS-41668_PIA22519_original_marci-dgm-v04-for-home-page-5.gifThe Global Dust Storm that wiped Oppy away118 visiteCaption NASA:"This set of images from NASA’s Mars Reconnaissance Orbiter (MRO) shows a fierce, giant Dust Storm is kicking up on Mars, with Rovers on the Surface indicated as icons. The spread of the Storm can be seen in the salmon-colored overlay. These images from MRO's Mars Color Imager start from May 31, when the Dust Event was first detected, and go through June 11, 2018.
MRO creates Global Maps of Mars but roll maneuvers for targeted observations produce gaps in the coverage, which appear as black gores in the aforementioned Maps. On some days there are data drops where partial or full orbits of coverage are missing. Green and purple observed in the South Polar Region indicate saturated pixels. Latitude is indicated along the Vertical Axis. Longitude is indicated along the Horizontal Axis".MareKromiumNov 17, 2019
|
|
Dust_Storm-MGS-41669_Zurek-1-PIA22519.gifThe Global Dust Storm that wiped Oppy away (Annotated)118 visiteCaption NASA:"This set of images from NASA’s Mars Reconnaissance Orbiter (MRO) shows a fierce, giant Dust Storm is kicking up on Mars, with Rovers on the Surface indicated as icons. The spread of the Storm can be seen in the salmon-colored overlay. These images from MRO's Mars Color Imager start from May 31, when the Dust Event was first detected, and go through June 11, 2018.
MRO creates Global Maps of Mars but roll maneuvers for targeted observations produce gaps in the coverage, which appear as black gores in the aforementioned Maps. On some days there are data drops where partial or full orbits of coverage are missing. Green and purple observed in the South Polar Region indicate saturated pixels. Latitude is indicated along the Vertical Axis. Longitude is indicated along the Horizontal Axis".MareKromiumNov 17, 2019
|
|
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)67 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.MareKromiumMag 07, 2014
|
|
| 2237 immagini su 187 pagina(e) |
1 |
 |
|
|
|
|
|
|
|
|
|
