PIA15283: Dunes in Noachis Terra Region of Mars January 25, 2012Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: High Resolution Imaging Science Experiment, HiRISE, JPL-Caltech, Mars, Mars Reconnaissance Orbiter (MRO), NASA, Noachis Terra, University of Arizona
This enhanced-color image shows sand dunes trapped in an impact crater in Noachis Terra, Mars. Dunes and sand ripples of various shapes and sizes display the natural beauty created by physical processes. The area covered in the image is about six-tenths of a mile (1 kilometer) across.
Sand dunes are among the most widespread wind-formed features on Mars. Their distribution and shapes are affected by changes in wind direction and wind strength. Patterns of dune erosion and deposition provide insight into the sedimentary history of the surrounding terrain.
The image is one product from an observation by the High Resolution Imaging Science Experiment (HiRISE) camera taken on Nov. 29, 2011, at 42 degrees south latitude, 42 degrees east longitude. Other image products from the same observation are at http://www.uahirise.org/ESP_025042_1375.
HiRISE is one of six instruments on NASA’s Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates the orbiter’s HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for the NASA Science Mission Directorate, Washington.
NASA/JPL-Caltech/Univ. of Arizona
Image Addition Date:
The Crazy Floor of Hellas Basin July 30, 2011Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: Alfred McEwen, Hellas Impact Basin, HiRISE, JPL, Mars, Mars Reconnaissance Orbiter (MRO), NASA, University of Arizona
The deep floor of Hellas impact basin is often obscured by haze, but at times we get some clear views. There are some strange landforms down there, and this image is one example.
The image covers the rim region of a crater that appears filled in, perhaps by river sediment (the rim is breached by a channel). The colors (see enhanced color subimage) indicate that diverse minerals are present.
Alfred McEwen (27 July 2011)
A Dark Dune Field in Proctor Crater on Mars November 28, 2010Posted by John Tintle (MtO deadbait) in Planets.
Tags: HiRISE, Mars, Mars Reconnaissance Orbiter (MRO), NASA, Proctor Crater, University of Arizona
Was this image taken with a telescope or a microscope? Perhaps this clue will help: if the dark forms were bacteria, they would each span over football field across. What is actually being seen are large sand dunes on the floor of Proctor Crater on Mars. The above picture was taken by HiRISE camera on board the Mars Reconnaissance Orbiter (MRO), a robot spacecraft currently in orbit around Mars. The dark rippled dunes likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago.
Eroding Layers in an Impact Crater February 13, 2010Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: Colin Dundas, HiRISE, JPL, Mars, NASA, University of Arizona
NASA/JPL/University of Arizona, Colin Dundas
This image shows a stack of layers on the floor of an impact crater roughly 30 kilometers across. Many of the layers appear to be extremely thin, and barely resolved.
In broad view, it is clear that the deposit is eroding into a series of ridges, likely due to the wind. Below the ridges, additional dark-toned layered deposits crop out. These exhibit a variety of textures, some of which may be due to transport of material.
The light ridges are often capped by thin dark layers, and similar layers are exposed on the flanks of the ridges. These layers are likely harder than the rest of the material, and so armor the surface against erosion. They are shedding boulders which roll down the slope, as shown in the subimage. Although these cap layers are relatively resistant, the boulders do not seem to accumulate at the base of the slope, so it is likely that they also disintegrate relatively quickly.
The subimage itself is 250 meters wide. The light is from the left. Boulders are visible on the slopes of the ridges along with thin dark layers including the cap layer, but they are absent on the spurs where the resistant cover has been eroded. This demonstrates that the boulders come only from the dark layers, and are not embedded in the rest of the deposit.
North Polar Layered Deposits in Head Scarp of Chasma Boreale January 9, 2010Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: Chasma Boreale, HiRISE, JPL, Ken Herkenhoff, Mars, NASA, Unversity of Arizona
NASA/JPL/University of Arizona, Ken Herkenhoff
This false-color subimage shows the north polar layered deposits at top and darker materials at bottom exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits.
The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. The water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp.
The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the cross-bedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places.
Exposures such as these are useful in understanding the recent climate variations that are likely recorded in the polar layered deposits.
Alluvial Fans in Mojave Crater: Did It Rain on Mars? January 8, 2010Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: Alfred McEwen, HiRISE, JPL, Mars, Mars Orbital Camera, Mojave Crater, NASA, University of Arizona, Xanthe Terra
NASA/JPL/University of Arizona, Alfred McEwen
Aptly-named Mojave Crater in the Xanthe Terra region has alluvial fans that look remarkably similar to landforms in the Mojave Desert of southeastern California and portions of Nevada and Arizona.
Alluvial fans are fan-shaped deposits of water-transported material (alluvium). They typically form at the base of hills or mountains where there is a marked break, or flattening of slope.
They typically deposit big rocks near their mouths (close to the mountains) and smaller rocks at greater distances. Alluvial fans form as a result of heavy desert downpours, typically thundershowers. Because deserts are poorly vegetated, heavy and short-lived downpours create a great deal of erosion and nearby deposition.
There are fans inside and around the outsides of Mojave crater on Mars that perfectly match the morphology of alluvial fans on Earth, with the exception of a few small impact craters dotting this Martian landscape.
Channels begin at the apex of topographic ridges, consistent with precipitation as the source of water, rather than groundwater. This remarkable landscape was first discovered from Mars Orbital Camera images. Mars researchers have suggested that impact-induced atmospheric precipitation may have created these unique landscapes.
This HiRISE image at up to 29 cm/pixel scale supports the alluvial fan interpretation, in particular by showing that the sizes of the largest rocks decrease away from the mouths of the fans.
Starburst Spider (ESP_011842_0980) March 25, 2009Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: HiRISE, JPL, Mars, NASA, University of Arizona
NASA/JPL/University of Arizona
Mars’ seasonal cap of carbon dioxide ice (dry ice) has eroded many beautiful terrains as it sublimates (goes directly from ice to vapor) every spring. In this region we see troughs that form a starburst pattern.
In other areas these radial troughs have been referred to as “spiders,” simply because of their shape. In this region the pattern looks more dendritic as channels branch out numerous times as they get further from the center. The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below. The dust falls to the surface of the ice in fan-shaped deposits.
Mars’ Moon Deimos March 12, 2009Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: Deimos, HiRISE, JPL-Caltech, Mars, Mars Reconnaissance Orbiter (MRO), NASA, University of Arizona
These color-enhanced views of Deimos, the smaller of the two moons of Mars, were taken on Feb. 21, 2009, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. Deimos is about 7.5 miles in diameter.
Deimos has a smooth surface due to a blanket of fragmental rock or regolith, except for the most recent impact craters. It is a dark, reddish object, very similar to Mars’ other moon, Phobos.
These Deimos images combine HiRISE exposures in near-infrared, red and blue-green wavelengths. In the enhanced color, subtle color variations are visible — redder in the smoothest areas and less red near the fresh impact craters and over ridges of topographic highs. The color variations are probably caused by exposure of surface material to the space environment, which leads to darkening and reddening. Brighter and less-red surface materials have seen less exposure to space due to recent impacts or downslope movement of regolith.
NASA/JPL-Caltech/University of Arizona
Layering in Uzer Crater Wall October 18, 2008Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: HiRISE, JPL, Mars, Mars Reconnaissance Orbiter (MRO), NASA, Sinus Meridiani, University of Arizona, Uzer Crater
NASA/JPL/University of Arizona
This image shows a portion of Uzer Crater, located in Sinus Meridiani near the equator in the northern hemisphere of Mars.
Light-toned layered rocks are visible on the wall of Uzer Crater. Differences in color highlight variations in the layered units. Wind erosion, in particular, has modified the layers since exposure creating rounded depressions. These layers are interpreted to be an outcrop of sedimentary rocks that formed by sediments once deposited in this area. The origin of the sediments composing the layers is unknown but may have included fluvial processes and wind blown particles such as dust or volcanic ash.
Over time, the sediments were solidified into rock and eventually exposed when an impact formed Uzer Crater. Northern Sinus Meridiani has many similar outcrops of light-toned sedimentary material that are observed over a large region.
On Mars, as on Earth, sedimentary rocks preserve a record of past environments. HiRISE color images reveal details in the layers that will help scientists learn more about their origin.
Crater on North Polar Layered Deposits October 16, 2008Posted by John Tintle (MtO deadbait) in Planets, Space Fotos.
Tags: HiRISE, JPL, Mars, Mars Reconnaissance Orbiter (MRO), NASA, University of Arizona
NASA/JPL/University of Arizona
The north polar layered deposits, and the bright ice cap that covers them, are very young (by geologic standards) features. To try and figure out the age of an area, or how quickly it’s being resurfaced, planetary scientists count up the number of craters at different sizes. An older surface has more time to accumulate more craters whereas a younger surface, or one that has a lot of geologic activity that destroys craters, doesn’t have many impact craters.
These polar deposits have a very low crater count so it is possible that the ice cap (bright white in this image) might only by about 10,000 years old and the surface of the layered deposits (orange-brown in this image) may be only a few million years old. This sounds like a long time but is very short compared to other surfaces on Mars.
HiRISE is enabling a more detailed study of these polar craters and the target of this observation is visible in the center of the image. This crater proved to be a surprise in a few ways. Its shape is non-circular which is quite unusual for an impact crater. One possibility is that flow of the ice beneath the surrounding terrain has deformed the crater; however, ice-flow rates are thought to be very low on Mars today.
The crater also contains a patch of bright ice despite being surrounded by terrain that has mostly lost its ice cover. This seems typical for these polar craters and it may be that ice within these craters is protected from ablation by shading from the crater walls.