| Piú votate - Mars Reconnaissance Orbiter (MRO) |
PSP_003608_1510_RED_abrowse-01.jpgProximities of Zumba Crater: Secondary Craters Field (Natural - but enhanced - Colors; credits: Lunar Explorer Italia)57 visitenessun commentoMareKromium
(5 voti)
|
|
ESP_012435_2015_RED_abrowse.jpgBranched Features on the Floor of Antoniadi Crater (Natural Colors; credits: Lunar Explorer Italia)59 visiteThe dark branched features in the floor of Antoniadi Crater look like giant ferns, or fern casts. However, these ferns would be several miles in size and are composed of rough rocky materials.
A more likely hypothesis is that this represents a channel network that now stands in inverted relief. The channels may have been lined or filled by indurated materials, making the channel fill more resistant to erosion by the wind than surrounding materials. After probably billions of years of wind erosion the resistant channels are now relatively high-standing. The material between the branched ridges has a fracture pattern and color similar to deposits elsewhere on Mars that are known to be rich in hydrated minerals such as clays.
The inverted channels have short, stubby branches characteristic of formation by groundwater sapping. Spring water seeps into the channels and undercuts overlying layers which collapse, so the channels grow headward. These images tell the story of an ancient wet environment on Mars, where life could have been possible. Ancient Martian life was most likely to consist of microorganisms rather than giant tree ferns.
MareKromium
(5 voti)
|
|
ESP_012725_2015_RED_abrowse.jpgBranched Features on the Floor of Antoniadi Crater (Natural Colors; credits: Lunar Explorer Italia)58 visitenessun commentoMareKromium
(5 voti)
|
|
PSP_002882_0940_RED_browse~0.jpgFresh Craters on the South Polar Layered Deposits (Natural Colors; credits: Lunar Explorer Italia)57 visiteThis image was taken in the Southern Spring, when the surface was completely covered by Carbon Dioxide frost. Therefore, most of the brightness variations in this scene are caused by topography.
The Polar Layered Deposits are broken into blocks by fractures in two directions. Neither set of fractures is parallel to the current scarp face, suggesting that they were not formed as the scarp was eroded, but instead are due to pre-existing weaknesses in the Polar Layered Deposits.
The (small?) craters that can be seen at about 23:00 - approx. in the central portion of the frame - appear to have formed at the same time by an impactor that broke up as it entered the Martian Atmosphere.
The presence of many craters such as these on the South Polar Layered Deposits indicates that they are not as young as the North Polar Layered Deposits, which have very few craters on them.MareKromium
(5 voti)
|
|
ESP_012270_2035_RED_abrowse.jpgFlood-Carved Rock in Olympica Fossae (Natural Colors; credits: Lunar Explorer Italia)59 visiteThis HiRISE image is part of the Olympica Fossae in the Tharsis Region of Mars.
Tharsis is most famous for being the home of the four largest Volcanoes in the Solar System. However, the Region also hosts a variety of other geologic features formed as the ground deformed under the tremendous weight of the Volcanoes.
Most of the Fissures (or “Fossae”) in the Region are primarily places where the ground was pulled apart. However, the Olympica Fossae are somewhat different. They are oriented at an angle to the other Fissures suggesting that some other process was important in their formation.
A close-up image reveals that erosion by one or more catastrophic floods may have played a key role.
The teardrop shaped islands and the parallel ridges are rock left standing after the flood erosion. However, the deepest depression running basically East-West through the middle of the image was probably caused by tectonic extension, not flood erosion. This juxtaposition of tectonic and flood-carved valleys is visible elsewhere on Mars, suggesting that it may be common for the tectonic fracturing to release copious volumes of subterranean water.MareKromium
(5 voti)
|
|
ESP_011543_1665_RED_abrowse.jpgPossible "Megabreccia" in Coprates Chasma (Natural Colors; credits: Lunar Explorer talia)58 visitenessun commentoMareKromium
(5 voti)
|
|
ESP_012425_1455_RED_abrowse.jpgUnusually-looking "Circular Surface Feature" (possible True Colors; credits: Dr G. Barca)59 visiteThis circular feature is a collection of hills, with some connected by ridges. The circularity suggests that perhaps there was once an impact crater here that was subsequently filled with material which was somehow more resistant to erosion than the landscape around it. Over time, as erosion stripped away the ground, the fill material was left standing higher (although it has clearly been eroded as well).
Nota Lunexit: si tratta di un "Exhumed Crater", ossìa di un cratere prima ricoperto da detriti e sedimenti e poi, a seguito di azioni prevalentemente eoliche (un vero e proprio scorticamento del suolo), è stato riportato - parzialmente - alla luce. Lo scorticamento che evidenzia il cratere sepolto è indice del fatto che i materiali i quali lo avevano ricoperto erano più resistenti e stabili dei materiali che circondano il cratere stesse (i quali, appunto, sono stati smossi dai venti). Un fenomeno similare, ma relativo ai canali, dà luogo ai cosiddetti "Inverted Channels", di cui si è già parlato in passatoMareKromium
(5 voti)
|
|
ESP_011527_1325_RED_abrowse.jpgSouthern Dunes and Volatiles (Natural Colors; credits: Lunar Explorer Italia)58 visitenessun commentoMareKromium
(5 voti)
|
|
ESP_011345_0950_RED_abrowse.jpgSmall Fan-like Surface Features on the South Polar Perennial Cap (Natural Colors; credits: Lunar Explorer Italia)59 visiteMars Local Time: 17:54 (late afternoon)
Coord. (centered): 84,8° South Lat. and 339,3° East Long.
Spacecraft altitude: 247,7 Km (such as about 154,8 miles)
Original image scale range: 99,1 cm/pixel (with 1 x 1 binning) so objects ~ 2,97 mt across are resolved
Map projected scale: 1 mt/pixel
Map projection: EQUIRECTANGULAR
Emission Angle: 0,9°
Phase Angle: 88,7°
Solar Incidence Angle: 89° (meaning that the Sun is about 1° above the Local Horizon)
Solar Longitude: 181,0° (Northern Autumn)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer ItaliaMareKromium
(5 voti)
|
|
ESP_011460_0980_RED_abrowse.jpgMonitor Seasonal Changes at a South Polar Cracked and Gullied Site (Natural Colors; credits: Lunar Explorer Italia)72 visiteMars Local Time: 17:02 (middle afternoon)
Coord. (centered): 81,7° South Lat. and 66,3° East Long.
Spacecraft altitude: 246,5 Km (such as about 154,1 miles)
Original image scale range: 49,3 cm/pixel (with 1 x 1 binning) so objects ~ 1,48 mt across are resolved
Map projected scale: 50 cm/pixel
Map projection: EQUIRECTANGULAR
Emission Angle: 1,2°
Phase Angle: 86,5°
Solar Incidence Angle: 85° (meaning that the Sun is about 5° above the Local Horizon)
Solar Longitude: 186,1° (Northern Autumn)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer ItaliaMareKromium
(5 voti)
|
|
Mud_Volcano-MRO.jpgMud Volcanoes on Mars? (Natural Colors; credits: Lunar Explorer Italia)58 visiteDa "NASA - Picture of the Day" del giorno 30 Marzo 2009:"Is this a Mud Volcano on Mars? If so, could it be dredging up Martian Microbes? This strange possibility has been suggested recently and seems to fit several recent observations of Mars.
First of all, hills like this seem to better resemble Mud Volcanoes on Earth than Lava Volcanoes and Impact Craters on Mars.
Next, the pictured dome has an unusually textured surface consistent with fractured ice. Infrared images from space indicate that hills like this cool more quickly than surrounding rock, consistent with a dried mud composition.
The hills also reflect colors consistent with a composition that formed in the presence of water.
Finally, unusual plumes of gas containing Methane have been found on Mars with unknown origin. These gas plumes could conceivably have been liberated by Mud Volcanoes, were the initially warm mud to contain Methane-producing microbes drifting in a previously unobservable underground lake.
A candidate mud volcano over 100 meters across is pictured above in the Northern Plains (Vastitas Borealis Region) of Mars".MareKromium
(5 voti)
|
|
ESP_011386_2065_cut.jpgCollapse Pit in Tractus Fossae (edm - Vertical View - Natural Colors; credits: Lunar Explorer Italia)58 visiteThis HiRISE image shows a collapse pit in Tractus Fossae, a Region of large Ridges and Troughs created by Tectonic Activity.
The Fossae occur on the Tharsis Volcanic Rise, a giant region of enhanced volcanic activity that includes the 3 large volcanoes Ascraeus Mons, Pavonis Mons and Arsia Mons.
The Pit in this image has very steep walls, and so only a narrow arc is illuminated by Sunlight. The rest of the Pit is in dark shadow.
However, a stretched version of the image shows details of the pit floor, due to a small amount of scattered Sunlight.
Pits like this form by collapse into underground voids, such as those left by propagating magma-filled dikes.
They may sometimes have overhanging walls, although in this case the walls can be seen and appear nearly vertical. Some similar features are found on Earth: Devil’s Throat, in Hawaii, is one example.
Other similar examples have been imaged on Mars as well.MareKromium
(5 voti)
|
|
| 2235 immagini su 187 pagina(e) |
 |
|
|
|
|
34 | |
|
|
|
|
