google.com, pub-0288379932320714, DIRECT, f08c47fec0942fa0 GRAVIR LES MONTAGNES... EN PEINTURE: NASA MARS RECONNAISSANCE ORBITER (2005-2015)
Showing posts with label NASA MARS RECONNAISSANCE ORBITER (2005-2015). Show all posts
Showing posts with label NASA MARS RECONNAISSANCE ORBITER (2005-2015). Show all posts

Wednesday, April 3, 2019

ANSERIS MONS BY NASA MARS RECONNAISSANCE ORBITER





NASA MARS RECONNAISSANCE ORBITER (2005-2015)
Anseris Mons (6,200 m -20,300 ft)
MARS 

The mountain

Anseris Mons (6,200 m -20,300 ft) is an isolated massif of mountains in the southern highlands of Mars, located at the northeastern edge of Hellas Planitia at longitude 86.65°E and latitude 29.81°S. The mountain is 58 km (36 mi) in diameter and lies in the southeastern quarter of the Iapygia quadrangle (MC-21), straddling the boundary with the adjoining Hellas quadrangle (MC-28) to the south.,Anseris Mons is named from Anseris Fons, a telescopic albedo feature mapped by Greek astronomer E. M. Antoniadi in 1930. The name was approved by the International Astronomical Union (IAU) in 1991.
Anseris Mons is not a volcano. Geologically, the massif is thought to be the eroded remnant of an ancient crustal block uplifted from depths of several kilometers in the formation of the Hellas impact basin during the period of heavy bombardment. Anseris Mons is the type area for a large set of rugged mountain blocks (>25 km across) that occur in a relatively continuous band 200 to 500 km wide around the western, northeastern, eastern, and southeastern rim of the Hellas basin. Many of the blocks, particularly along the western rim, are concentric with the basin and bounded by faults.
Rocks making up Anseris Mons and other massifs around Hellas are mapped as Noachian in age. However, work by Herbert Frey at NASA’s Goddard Spaceflight Center using Mars Orbital Laser Altimeter (MOLA) data indicates that the southern highlands of Mars contain numerous buried impact basins that are older than the visible Noachian-aged surfaces and which pre-date the Hellas impact. He suggests that the Hellas impact should mark the beginning of the Noachian period (base of the Noachian system). If Frey is correct, then Anseris Mons bedrock is actually pre-Noachian in age, perhaps dating back to over 4.1 billion years ago.
The Anseris Mons massif has undergone a significant amount of erosion since it was uplifted. The flanks of the mountain have huge triangular re-entrants and associated spurs, which give the massif a broad, pyramidal shape. The re-entrants were likely produced through a variety of mass-wasting and periglacial/glacial processes. A large cirque-like re-entrant with channelized debris aprons or fans is present on the south side of the mountain.

Wednesday, January 3, 2018

ASCRAEUS MONS SEEN BY NASA MARS RECONNAISSANCE ORBITER




NASA MARS RECONNAISSANCE ORBITER (2005-2015) 
Ascraeus mons (18, 225m / 18, 1 kms- 50, 793 ft / 11, 1mi) 
Planet Mars

1.  In Ascraeus monsHiRISE camera ,Mars Reconnaissance Orbiter (MRO); November 2010
2.  In  Colorized MOLA topography of Ascraeus Mons, 2006   


The mountain 
Ascraeus mons (18, 225m / 18kms- 50, 793 ft / 11, 1mi)  is a large shield volcano located in the Tharsis region of the planet Mars. It is the northernmost and tallest of three shield volcanoes collectively known as the Tharsis Montes. The volcano's location corresponds to the classical albedo feature Ascraeus Lacus.
Ascraeus Mons was discovered by the Mariner 9 spacecraft in 1971. The volcano was originally called North Spot because it was the northernmost of only four spots visible on the surface due to a global dust storm that was then enshrouding the planet. As the dust cleared, the spots were revealed to be extremely tall volcanoes whose summits had projected above the dust-laden, lower atmosphere.
The volcano is located in the southeast-central portion of the Tharsis quadrangle at 11.8°N, 255.5°E in Mars' western hemisphere.  Ascraeus Mons is roughly 480 km in diameter and is the second highest mountain on Mars, with a summit elevation of 18.1 km ! The volcano has a very low profile with an average flank slope of 7°. Slopes are steepest in the middle portion of the flanks, flattening out toward the base and near the top where a broad summit plateau and caldera (collapse crater) complex are located.
Volcanic vents, located on the northeastern and southwestern edges of the volcano, are sources for broad lava aprons, or fans, that bury nearby portions of the volcano and extend over 100 km out into the surrounding plains.  The southwest-northeast orientation of the aprons matches the orientation of the Tharsis Montes, suggesting that a major fissure or rift in the Martian crust is responsible for the orientation of both the aprons and the Tharsis Montes chain. The presence of the lava aprons causes some disagreement in the actual dimensions of the volcano.
Like most of the Tharsis region, Ascraeus Mons has a high albedo (reflectivity) and low thermal inertia, indicating that the volcano and surrounding areas are covered with large amounts of fine dust.  The dust forms a mantle over the surface that obscures or mutes much of the fine-scale topography and geology of the region. Tharsis is probably dusty because of its high elevations. The atmospheric density is too low to mobilize and remove dust once it is deposited.
Ascraeus Mons is surrounded by lava flow plains that are mid to late Amazonian in age. The elevation of the plains averages about 3 km above datum (Martian "sea" level), giving the volcano an average vertical relief of 15 km.  However, the elevation of the plains varies considerably. The plains northwest of the volcano are less than 2 km in elevation. The plains are highest (>3 km) southeast of the volcano.
The lava plains northwest of Ascraeus Mons are notable for having two dark collapse pits photographed by the HiRISE camera on the Mars Reconnaissance Orbiter (MRO) in November 2010 (image above) . The pits resemble those imaged around Arsia Mons by the Mars Odyssey spacecraft. The two pits measure about 180 and 310 m wide, and the larger pit is approximately 180 meters deep. The eastern walls of the pits consist of steep, overhanging ledges. The bottoms of both pits contain sediments and large boulders.  These rimless pit craters are believed to form by collapse of surface material into a subsurface void created either by a dike or lava tube. They are analogous to volcanic pit craters on Earth, such as the Devil's Throat crater on the upper east rift zone of Kilauea Volcano, Hawaii.  In some cases, they may mark skylights/entrances to subsurface lava caves.

The camera
The image above, has been captured by the HiRISE  (High Resolution Imaging Science Experiment) camera aboard NASA’s Mars Reconnaissance Orbiter. The 65 kg (143 lb), $40 million USD instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp. It consists of a 0.5 m (19.7 in) aperture reflecting telescope, the largest so far of any deep space mission, which allows it to take pictures of Mars with resolutions of 0.3 m/pixel (about 1 foot), resolving objects below a meter across.
HiRISE has imaged Mars landers on the surface, including the ongoing Curiosity and Opportunity rover missions.
HiRISE was designed to be a High Resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves a resolution of 1 microradian, or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images on Google Mars are available to 1 meter). It can image in three color bands, 400–600 nm (blue-green or B-G), 550–850 nm (red) and 800–1,000 nm (near infrared or NIR).
HiRISE incorporates a 0.5-meter primary mirror, the largest optical telescope ever sent beyond Earth's orbit. The mass of the instrument is 64.2 kg.
Red color images are at 20,048 pixels wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). These are gathered by 14 CCD sensors, 2048 x 128 pixels. HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed, meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gbit (3.5 GByte) memory capacity. The nominal maximum size of red images (compressed to 8 bits per pixel) is about 20,000 × 126,000 pixels, or 2520 megapixels and 4,000 × 126,000 pixels (504 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses up to 28 Gbit. However, these images are transmitted compressed, with a typical max size of 11.2 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000.
To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter.
The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. It has provided a closer look at fresh martian craters, revealing alluvial fans, viscous flow features and ponded regions of pitted materials containing breccia clast.  This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing the Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, and other surface landforms as they exist on the Martian surface.
The general public is allowed to request sites for the HiRISE camera to capture (see HiWish). For this reason, and due to the unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has been termed "The People's Camera".
 The pictures can be viewed online, downloaded, or with the free HiView software.

Thursday, November 10, 2016

HALE CRATER MOUNTAINS SEEN BY NASA MARS RECONNAISSANCE ORBITER





NASA MARS RECONNAISSANCE ORBITER MISSION (2005-2015)
Hale Crater Mountains  (150 kms diameter -  93 mile diameter)
Planet Mars  (Argyre quadrangle)

1 & 2. Hale crater mountains slope seeping waters
3. Hale crater mountains gullies.

The "mountains" 
Hale is a 150 km x 125 km (93 mi x 78 mi) crater located at 35.7°S, 323.4°E, just north of Argyre basin on Mars, the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury, often nicknamed "The red planet" because the iron oxide prevalent on its surface. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.
The Hale crater is situated in the Argyre quadrangle of the planet.  
On 28 September 2015 NASA confirmed the seasonal existence of liquid water in Hale crater. The salts in the water (magnesium perchlorate, magnesium chlorate, sodium perchlorate,...) lower its freezing and melting point to 203 K (−70 °C or −94 °F), which is near the average summer night temperature. 

Hale was created by an asteroid roughly 35 km (22 mi) across that impacted at an oblique angle about 3.5–3.8 billion years ago. The rim and ejecta are eroded and show smaller impacts, but subsequent deposits have covered up small craters within it.  On the southern rim of Hale, parts of the crater wall have moved downslope towards the crater's centre. The surface shows a network of fluvial channels which may have been caused by running water.
It is named after George Ellery Hale, an astronomer from Chicago who determined in 1908 that sunspots are the result of magnetic activity.
The wall of Hale Crater has a large number of gullies. Some are pictured below in an image from HiRISE. Unlike, some other gullies on Mars, these are in light-toned materials. Research published in the journal Icarus has found pits in Hale Crater that are caused by hot ejecta falling on ground containing ice. The pits are formed by heat forming steam that rushes out from groups of pits simultaneously, thereby blowing away from the pit ejecta.
Gullies occur on steep slopes, especially craters. Gullies are believed to be relatively young because they have few, if any craters, and they lie on top of sand dunes which are young. Usually, each gully has an alcove, channel, and apron. Although many ideas have been put forward to explain them, the most popular involve liquid water either coming from an aquifer or left over from old glaciers.
There is evidence for both theories. Most of the gully alcove heads occur at the same level, just as one would expect of an aquifer. Various measurements and calculations show that liquid water could exist in an aquifer at the usual depths where the gullies begin. One variation of this model is that rising hot magma could have melted ice in the ground and caused water to flow in aquifers. Aquifers are layer that allow water to flow. They may consist of porous sandstone. This layer would be perched on top of another layer that prevents water from going down (in geological terms it would be called impermeable). The only direction the trapped water can flow is horizontally. The water could then flow out onto the surface when it reaches a break, like a crater wall. Aquifers are quite common on Earth. A good example is "Weeping Rock" in Zion National Park Utah.
On the other hand, much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smoothes the land, but in places it has a bumpy texture, resembling the surface of a basketball. Under certain conditions the ice could melt and flow down the slopes to create gullies. Because there are few craters on this mantle, the mantle is relatively young.
Changes in Mars's orbit and tilt cause significant changes in the distribution of water ice from polar regions down to latitudes equivalent to Texas. During certain climate periods water vapor leaves polar ice and enters the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. The atmosphere of Mars contains a great deal of fine dust particles. Water vapor will condense on the particles, then fall down to the ground due to the additional weight of the water coating. When ice at the top of the mantling layer goes back into the atmosphere, it leaves behind dust, which insulates the remaining ice.

The camera
The image above, has been captured by the HiRISE  (High Resolution Imaging Science Experiment) camera aboard NASA’s Mars Reconnaissance Orbiter. The 65 kg (143 lb), $40 million USD instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp. It consists of a 0.5 m (19.7 in) aperture reflecting telescope, the largest so far of any deep space mission, which allows it to take pictures of Mars with resolutions of 0.3 m/pixel (about 1 foot), resolving objects below a meter across.
HiRISE has imaged Mars landers on the surface, including the ongoing Curiosity and Opportunity rover missions.
HiRISE was designed to be a High Resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves a resolution of 1 microradian, or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images on Google Mars are available to 1 meter). It can image in three color bands, 400–600 nm (blue-green or B-G), 550–850 nm (red) and 800–1,000 nm (near infrared or NIR).
HiRISE incorporates a 0.5-meter primary mirror, the largest optical telescope ever sent beyond Earth's orbit. The mass of the instrument is 64.2 kg.
Red color images are at 20,048 pixels wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). These are gathered by 14 CCD sensors, 2048 x 128 pixels. HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed, meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gbit (3.5 GByte) memory capacity. The nominal maximum size of red images (compressed to 8 bits per pixel) is about 20,000 × 126,000 pixels, or 2520 megapixels and 4,000 × 126,000 pixels (504 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses up to 28 Gbit. However, these images are transmitted compressed, with a typical max size of 11.2 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000.
To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter.
The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. It has provided a closer look at fresh martian craters, revealing alluvial fans, viscous flow features and ponded regions of pitted materials containing breccia clast.  This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing the Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, and other surface landforms as they exist on the Martian surface.
The general public is allowed to request sites for the HiRISE camera to capture (see HiWish). For this reason, and due to the unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has been termed "The People's Camera".
 The pictures can be viewed online, downloaded, or with the free HiView software.