The University of Arizona press release is reproduced below:

By Lori Stiles, University Communications
March 6, 2008

Scientists studying images from The University of Arizona-led High Resolution Imaging Experiment camera on NASA's Mars Reconnaissance Orbiter have discovered never-before-seen impact "megabreccia" and a possibly once-habitable ancient lake on Mars at a place called Holden crater.


The HiRISE camera on the Mars Reconnaissance
Orbiter took this image of the largest fan in
Holden crater when the orbiter was flying
about 162 miles over the surface in March
2007. Geologists discovered a complex
geologic history for the site, including two
wet episodes that may have been amenable
to life.
(NASA/JPL/University of Arizona)

The megabreccia is topped by layers of fine sediments that formed in what apparently was a long-lived, calm lake that filled Holden crater on early Mars, HiRISE scientists say.

The Holden crater image is on the HiRISE Website at _http://hirise.lpl.arizona.edu/PSP_003077_1530
"Holden crater has some of the best-exposed lake deposits and ancient megabreccia known on Mars," said HiRISE's principal investigator, professor Alfred McEwen of the UA's Lunar and Planetary Laboratory. "Both contain minerals that formed in the presence of water and mark potentially habitable environments. This would be an excellent place to send a rover or sample-return mission to make major advances in understanding if Mars supported life."


This schematic drawing
shows impact megabreccia,
the lowest layer, topped
by clay-containing lake
sediment layers, and again
topped again by sediments
deposited when the Holden
crater rim was breached
early in Mars history.

Holden crater is an impact crater that formed within an older, multi-ringed impact basin called Holden basin. Before an impact created Holden crater, large channels crossed and deposited sediments in Holden basin.

Blocks as big as 50 meters across were blasted from Holden basin when Holden crater formed, then fell chaotically back to the surface and eventually formed "megabreccia," a conglomeration of large, broken boulders mixed with smaller particles. HiRISE images show megabreccia outcrops in Holden crater walls. This megabreccia may be some of the oldest deposits exposed on the surface of Mars.

At least 5 percent, by weight, of the fine sediments in the layer on top of the megabreccia consists of clay, according to another instrument on the Mars Reconnaissance Orbiter, the Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM.



This is a more detailed close-up view of the HiRISE image
of Holden crater. It shows layers revealed when Holden
crater rim was breached, unleashing water that scoured
out parts of Holden crater. From the bottom up, these
include the base of impac megabreccia, contrasting
smooth sedimentary layers, another darker, crudely
layered unit, and dark wind-blown material on the surface.
These layers correspond to layers in the illustrative drawing,
above left.
(NASA/JPL/University of Arizona)

"The origin of the clays is uncertain, but clays in the probable lake sediments implies quiescent conditions that may preserve signatures of a past habitable environment," HiRISE co-investigator John Grant of the Smithsonian National Air and Space Museum said. "If we were looking on Earth for an environment that preserves signatures related to habitability, this is one of the kinds of environments we would look at."

And even the clay-containing layers aren't all that's icing the cake. Topping the clay layers that formed in the placid Holden crater lake are layers of great boulder-filled debris unleashed later, when water breached Holden crater rim, creating a torrential flood that eroded the older lake sediments.

The clay-rich layers would have remained buried from view, except for that great piece of luck, the fact that Holden crater rim could no longer withstand the force of an estimated 4,000 cubic kilometers of water dammed behind it. The body of water would have been larger than Lake Huron.

"The volume of water that poured through during this flood must have been spectacular," Grant said. "It ripped up finely bedded materials, including blocks 70 meters or 80 meters across ............................... blocks nearly the size of football fields."

The first, prolonged watery episode at Holden crater that settled out the fine-grain sediments probably lasted at least thousands of years. By contrast, the second lake, formed when the crater rim was breached, may have lasted only hundreds of years, not long at all, Grant said.

The megabreccia excavated when Holden crater formed is the first found on Mars, Grant said. "When large craters form, they produce very large blocks of material. We see them on Earth. Popigai Crater in Russia is one example. But we'd never seen them on Mars, and we knew they ought to be there. Now we've seen them with HiRISE."

The observations suggest that the clays originally could have formed before the impact created Holden crater in the older Holden basin. Many of the blocks in the megabreccia appear to erode more easily than the surrounding crater wall material. These blocks could be chunks of Holden basin sediments that predate the impact crater, Grant said. "These blocks could be derived from the earlier Holden basin that were excavated on impact, then later re-eroded, with the sediments settling to the bottom of the long-lived lake. It's intriguing to think the clays we see in Holden crater now might actually have been recycled."

Holden crater is one of six remaining landing site candidates for NASA's Mars Science Laboratory, a mission scheduled for launch next year.

So far, most evidence for sustained wet conditions on Mars is limited to the planet's earliest history, the HiRISE scientists say. While water certainly flowed over the planet later in its history, it may have flowed only in short-lived, or catastrophic events.

Grant is first author on a research paper about Holden crater, published in the journal Geology last week.

The mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, for the NASA Science Mission Directorate. Lockheed Martin Space Systems, based in Denver, is the prime contractor and built the spacecraft. Ball Aerospace and Technologies Corp., of Boulder, Colo., built the HiRISE camera, which is operated by the UA Lunar and Planetary Laboratory.

Source: UA Press Release

Release date Mar 6, 2008
Latitude: 5.22 S
Longitude: 270.28 E




This image of sulfate-containing deposits in Tithonium Chasma was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1538 UTC (11:38 a.m. EDT) on August 31, 2007 near 5.22 degrees south latitude, 270.48 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point.

Tithonium Chasma lies at the western end of the Valles Marineris canyon system. It extends approximately east-west for roughly 810 kilometers (503 miles), varies in width from approximately 10 to 110 kilometers (6 to 68 miles), and cuts into the Martian surface to a maximum depth of roughly 6 kilometers (4 miles).

The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft’s Thermal Emission Imaging System (THEMIS). The CRISM data covers an area centered on a ridge of erosion-resistant rock.

The center left image, an infrared false color image, reveals banded, light-colored material draped on the ridge. The center right image unveils the mineralogical composition of the area, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral) and purple polyhydrated sulfates (sulfates with multiple waters per mineral molecule).

The lower two images are renderings of data draped over topography with 7 times vertical exaggeration. These images provide a view of the topography and reveal how the sulfate deposits both cover and flank the ridge. Brighter, monohydrated sulfate (yellow) deposits revealed in the lower right image lies along the ridge’s northwest side and fall off into a small valley or depression, while darker polyhydrated sulfates (purple) lie along the ridge’s northeast flank. A deposit of both mono- and polyhydrated sulfates spanning the ridge near its crest also appears to be coarsely banded.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials — leading to new understanding of the climate.

Credit: NASA/JPL/JHUAPL/ASU

Source: CRISM

SUBIMAGES IN THIS OBSERVATION


(9.5MB)

In northern winter a seasonal polar cap composed of carbon dioxide ice (dry ice) forms in the north polar region. This cap covers a vast sea of dunes at high northern latitudes. In the spring the ice sublimates (evaporates directly from ice to gas) and this active process loosens and moves tiny dust particles.

The subimage shows a region of the dunes that are just beginning to lose their seasonal ice cover. In most of the image the dunes are a muted red color. Where the sun is shining on the steep dune crests the frost is gone and dark dust is free to cascade down the sides. This thin layer of dust, like slope streaks found elsewhere on Mars, flows down around obstacles and may come to rest mid-slope.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image shows a portion of the Utopia Planitia, marked by polygonal features bounded by cracks and depressions in the mantle that possess scalloped edges.

Scalloped pits are typical features of the Martian mid-latitude mantle. Their presence has led to hypotheses of the removal of subsurface material, possibly interstitial ice, by sublimation (ice going directly from the solid state to the gas state). Their formation most likely involves development of oval- to scalloped-shaped depressions that may coalesce together, leading to the formation of large areas of pitted terrain. Scalloped pits typically have a steep pole-facing scarp and a gentler equator-facing slope.

On the surface surrounding the scalloped depressions is a polygonal pattern of fractures. This is commonly associated with scalloped terrain, and indicates that the surface has undergone stress, potentially caused by subsidence (sinking), desiccation (drying out), or thermal contraction. These polygon features are similar to permafrost polygons that form in polar and high alpine regions on Earth by seasonal-to-annual contraction of the subsoil. On Earth, such polygon features are indicative of the presence of ground ice. Several cracks cut through the side of the scallops suggesting that they must be at least as deep as the scallops. The polygons may have been present previous to the erosion of the mantle.

The landforms we observe here most likely show that ice-rich permafrost is present or has been present geologically recently. At this latitude on Mars, the conditions of pressure and temperature allow water ice within the ground to sublime. The disappearance of the ice component of the ground probably leads to the formation of the depressions, a process that may still be active today.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

SUBIMAGES IN THIS OBSERVATION


(2MB; north is down)

This image shows an unnamed, bowl-shaped impact crater located in the Southern Highlands. The crater is approximately 4 kilometers (2.5 miles) in diameter and 600 meters (2,000 feet) deep.

The colors depicted in this image are not those we would see with our naked eyes. An infrared band and two visible bands (red and blue-green, respectively) have been combined to produce this false-color image. False color combinations are often utilized to look for subtle compositional differences that may not be evident in true color images.

This subimage (enhanced to exaggerate color contrast) shows part of the north-facing walls of the crater, deeply carved by landslides. Rocky layers, mostly purplish in color, can be followed for hundreds of meters, poking through the loose materials that cover the slopes. Locally, the rocky layers show patches of diverse colors (blue, green, yellow.) These colors may be indicative of compositional differences in the rocky layers.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This observation is centered within Antoniadi Crater. This crater, even prior to the MRO mission, was identified as a likely ancient lake (now dry) that was supplied by both surface water and ground water.

The image provides further tantalizing evidence of a water-rich past. Most of the flat parts of the image have a polygonal texture, which commonly forms when mud dries. In the center of the image are branched (“dendritic”) features that connect southward to a larger trunk-shaped landform; the branches resemble stream channels on Earth. Unlike active channels with water, these features are “inverted,” or elevated above the surrounding terrain. Again, in analogy with such features seen on our planet, these probably formed when materials deposited by the streams, such as coarse gravel, or chemical cementation after removal of the water, caused the channel bottoms to become resistant. Over time, natural erosion from wind and other processes left the inverted channels elevated above the surrounding terrain.

The branched features are probably remnants of small tributary streams that fed the larger trunk-shaped stream. It appears that the inverted streams lie on top of, and are therefore younger, than the polygons. This area may have first had a lake that later dried to form the polygons, followed by episodes of stream flow and erosion.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Miyamoto Crater is located in southwest Meridiani Planum (and southwest of the Mars Exploration Rover Opportunity landing site). This image shows fairly smooth plains and some areas covered by wind streaks, suggesting that wind is an active process here, depositing surface material downwind in the form of streaks.

This landing site is adjacent to the hematite-bearing plains unit where the Opportunity rover sits. The CRISM instrument has detected phyllosilicates (clay minerals) at this landing site, which scientists believe to have formed in the presence of water. The MSL rover would investigate the mineral diversity here, which includes phyllosilicates and sulfates.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Mawrth Vallis has a rich mineral diversity, including clay minerals that formed by the chemical alteration of rocks or loose “regolith” (soil) by water. The CRISM instrument on the MRO spacecraft detects a variety of clay minerals here, which could signify different processes of formation. The high resolution of the HiRISE camera helps us to see and trace out layers, polygonal fractures, and with CRISM, examine the distribution of various minerals across the surface.

This surface is scientifically compelling for the Mars Science Laboratory (MSL) rover, although some of the terrain can be somewhat rough. Scientists use HiRISE images to find the safest possible landing site for the rover.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Alluvial fans are deposits of sand, gravel, and sometimes boulders that were eroded from steep slopes (mountain fronts or basin walls) and deposited on plains at the base of the slope. Erosion of deep alcoves into the walls of Holden Crater (155 kilometers in diameter) provided sediment to these alluvial fans, that have coalesced into a large deposit called a bajada.

Most Martian impact craters that contain large alluvial fans are clustered between 18 and 29 degrees south, and the Holden bajada is the largest of these deposits recognized to date. Inverted channels are located on the alluvial fans, where the old stream beds were more resistant to later wind erosion than the fine-grained sediment deposited outside the channels; preferential erosion left the channel beds exposed as ridges. Many ripples of more recent, wind-blown sand are found between the older inverted channels.

The Mars Science Laboratory (MSL) would land on the bajada and drive across the traversable ripples to the south, where the inverted channels, layers, and evidence for past fluvial activity are located.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image shows part of the floor of a large crater in Arabia Terra, near Mars’ equator. A notable feature on this crater floor is a region of dark patches up to about 100 meters (330 feet) across. These dark patches sit in an area of connected small ridges and spurs and bury them, filling in the low areas and piling up. In several places light ridge crests protrude through the dark material.

The dark patches appear to be collections of wind-blown sand. Sand on Mars is often dark, likely because it is fragments of a volcanic rock called basalt. (Sand on Earth is most often light-toned quartz). Sand may tend to collect in patches that can ultimately evolve into large dunes if more sand gathers. The patches of sand here are not big enough to form such large structures, but small-scale regular texture due to blowing wind is visible on the surface.

The relatively dark tone which can be seen around the sand patches (compared with the surrounding material) is probably due to small amounts of additional sand. In some places this collects at the bottom of troughs.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image contains streamlined features located northwest of Hale Crater, a 120 x 150 kilometer diameter impact crater that is possibly the youngest of its size on Mars.

A streamlined feature is one that is raised, possessing sharp edges. It is narrower at the downstream end because of the flow that carved it. Any fluid—lava, water, mud, and even flowing ice—can form streamlined features. Many portions of the image are filled with craters, while others are rather smooth.

The streamlined features in this image tend to be smoother, suggesting they are relatively young. Their origin might be related to the impact that formed the crater.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Mawrth Vallis has a rich mineral diversity, including clay minerals that formed by the chemical alteration of rocks or loose “regolith” (soil) by water. The CRISM instrument on the MRO spacecraft detects a variety of clay minerals here, which could signify different processes of formation. The high resolution of the HiRISE camera helps us to see and trace out layers, polygonal fractures, and with CRISM, examine the distribution of various minerals across the surface.

This surface is scientifically compelling for the Mars Science Laboratory (MSL) rover, although some of the terrain can be somewhat rough. Scientists use HiRISE images to find the safest possible landing site for the rover.

This is one of four candidate landing sites in the Mawrth Vallis region.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image shows part of a crater wall and floor, where the floor is covered by dunes and distinct regions of bright material. The bright material stands higher than the rest of the floor suggesting that it is more resistant to erosion than surrounding materials.

It is possible that more and more bright material will be exposed over time; why the material is bright is unknown. The material might be evaporites, that form when salt water dries up and leaves behind salt deposits (the evaporites).

Also in this scene is a crater with a ridge running up to its west (left) side. The ridge is lighter and might be evidence that water flowed through it, bleaching the rocks as it went. The water might have cemented the soil, causing it to be more resistant to erosion and high standing as seen today.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

SUBIMAGES IN THIS OBSERVATION


(894kb)

This image shows slope streaks and layering on the walls of a valley along the border between the Martian southern highlands and northern lowlands (see the subimage). At the bottom of the valley and in the lower portion of the valley walls are many large dunes.

The slope streaks generally start at a point source and widen downslope as a single streak or branch into multiple streaks. Some of the slope streaks show evidence that downslope movement is being diverted around obstacles, such as large boulders. In particular, several of the slope streaks in this image appear to be diverting around individual dunes, with downslope movement occurring in the low troughs between the dunes. The darkest slope streaks are youngest and cross cut and lie on top of the older and lighter-toned streaks. The lighter-toned streaks are believed to be dark streaks that are lightening with time as new dust is deposited on their surface.

Slope streak formation is among the few known processes currently active on Mars. Since the slope streaks in this image appear to superpose (lie on top of) the surfaces between individual dunes, the streaks most likely formed more recently and are younger than the dunes.

Many hypotheses have been proposed for the formation of slope streaks including dry avalanching, geochemical weathering, liquid stains or flows, and moisture wickering. Recent observations from HiRISE images have revealed that the dark interior of slope streaks is lower in elevation than the surroundings, suggesting that material must have been removed in the formation of the streak.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Alluvial fans are deposits of sand, gravel, and sometimes boulders that were eroded from steep slopes (mountain fronts or basin walls) and deposited on plains at the base of the slope. Erosion of deep alcoves into the walls of Holden Crater (155 kilometers in diameter) provided sediment to these alluvial fans, that have coalesced into a large deposit called a bajada.

Most Martian impact craters that contain large alluvial fans are clustered between 18 and 29 degrees South, and the Holden bajada is the largest of these deposits recognized to date. Inverted channels are located on the alluvial fans, where the old stream beds were more resistant to later wind erosion than the fine-grained sediment deposited outside the channels; preferential erosion left the channel beds exposed as ridges. Many ripples of more recent, wind-blown sand are found between the older inverted channels.

The Mars Science Laboratory (MSL) would land on the bajada and drive across the traversable ripples to the south, where the inverted channels, layers, and evidence for past fluvial activity are located.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Release date Mar 18, 2008
Latitude: 7.50 S
Longitude: 327.25 E




This image of sulfate-containing deposits in Aurorae Chaos was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0653 UTC (2:53 a.m. EDT) on June 10, 2007, near 7.5 degrees south latitude, 327.25 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is roughly 12 kilometers (7.5 miles) wide at its narrowest point.

Aurorae Chaos lies east of the Valles Marineris canyon system. Its western edge extends toward Capri and Eos Chasmata, while its eastern edge connects with Aureum Chaos. Some 750 kilometers (466 miles) wide, Aurorae Chaos is most likely the result of collapsed surface material that settled when subsurface ice or water was released.

The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft’s Thermal Emission Imaging System (THEMIS). The CRISM data covers an area featuring several knobs of erosion-resistant material at one end of what appears to be a large teardrop shaped plateau. Similar plateaus occur throughout the interior of Valles Marineris, and they are formed of younger, typically layered rocks that post-date formation of the canyon system. Many of the deposits contain sulfate-rich layers, hinting at ancient saltwater.

The center left image, an infrared false color image, reveals a swath of light-colored material draped over the knobs. The center right image unveils the mineralogical composition of the area, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral).

The lower two images are renderings of data draped over topography with 5 times vertical exaggeration. These images provide a view of the topography and reveal how the monohydrated sulfate-containing deposits drape over the knobs and also an outcrop in lower-elevation parts of the plateau.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials — leading to new understanding of the climate.

Credit: NASA/JPL/JHUAPL/ASU

Source: CRISM

This image shows yardangs on the floor of Tithonium Chasma. Yardangs are elongated structures formed by aeolian (wind) erosion, developing as the wind exploits weaknesses in the rock, preferentially eroding them and streamlining the remnants. The result is a long, streamlined structure. Yardangs on Earth are found in areas of intense wind erosion, particularly where there is little rainfall; on Mars, yardangs are a common morphology in eroding sedimentary materials since wind is the major erosive process.

The rocks in this image are light-toned and likely sedimentary. The relatively blunt heads point northeast, towards the source of the wind which formed them. The yardangs have been further eroded and consist of chains of knobs and hills, roughly aligned. These may have once been consolidated ridges. If the rock was not of uniform strength, further erosion could have reduced ridges to aligned knobs by preferentially scouring away weak material.

Intriguing arcuate depressions are visible around several of the blunt northeast heads. These may be sites of preferential scouring and erosion where the wind flow was disrupted as it first encountered an obstacle. The most distinct examples of this are seen near the center of the image.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image shows layered bedrock exposed in the upper reaches of a topographic ridge located in Coprates Chasma. The layers exposed in the ridge visible in the upper part of the full image are darker toned, and possibly of volcanic origin.

The layers exposed in the lower part of the image are lighter toned and may be composed of hydrated sulfate minerals. An important question is whether or not the layers exposed here extend beneath the layers exposed in the upper part of the image, and are therefore older. Alternatively, the layers in the lower part of the image may rest on top of the ridge, and therefore be younger than the layered rocks which make up the ridge.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

The lower part of this image shows well-defined overlapping channels, which have inverted topography (i.e., they were once low spots that have been filled in with sediments and now eroded in a such a way that they appear as topographically high regions).

The channels have a winding and intersecting geometry indicating the shifting of the channels over time, a feature consistent with the flow of water in rivers. The channels have small craters that have excavated the channel materials and ejected them to form well-defined rays. There are dark slope streaks (toward the top of the image) showing transport of fine dust down the slope of an eroded bedrock terrain.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

The full range of the image shows clear evidence for a thick series of bedrock layers along the walls of Ganges Mensa, located in the Ganges Chasma portion of the large Valles Marineris chasm system.

These layers are of relatively uniform thickness and can be followed over long distances. The walls have weathered into a series of ridges where the layers can be traced laterally across the topography. The depressions between the ridges are partially filled with wind-blown sediments that form distinct dune fields.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

SUBIMAGES IN THIS OBSERVATION


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This observation is of region between large craters in Arabia Terra, which is a large swath of bright (high albedo) terrain in the Martian cratered uplands.

At the center of this image is a channel with a sinuous, fluvial-like (river-like) morphology, although it has long since been dry. The floor of the channel is covered with an array of linear dunes, which are accumulations of windblown sediment.

Of special interest in this scene is a series of dark (low albedo) and brighter (higher albedo) discolorations along the channel walls, also known as slope streaks. Most slope streaks are initially dark, gradually brighten with time, and are thought to be due to dust avalanches that remove a thin layer of bright dust to reveal darker material. Here, many streaks appear brighter than the surrounding undisturbed slope surface, and the origin of these bright streaks is not entirely clear.

In this subimage, it is apparent that dark streak always appear to be on top of the bright streaks, indicating that the dark streaks are younger.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

SUBIMAGES IN THIS OBSERVATION


(4MB)
Gale Crater is a large (152 kilometer diameter) crater in the cratered highlands of Mars near the highland/lowland divide. The crater contains a large central mound of layered, or stratified, material that is more than 2 km thick in some places.

Visible in this image is a deep chasm cutting through these layers, which are spectacularly exposed in the chasm walls. On the floor of this chasm is a sinuous, positive-relief feature that may be an inverted channel deposit. Inverted channels occur when sediment in a stream hardens and becomes cemented in place due to water-deposited minerals. After the flow ceased, later erosion removed the surrounding softer rock, leaving the cemented channel deposit as a positive rather than a negative relief feature.

This chasm may actually be classified as a canyon, which is specifically a chasm or gorge that was carved by running water.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

This image features a very fresh crater in the southern hemisphere. The crater is termed fresh because it is well-preserved with steep walls and obvious small-scale ejecta.

The crater has a set of dark rays extending from it; these rays are ejecta that sprayed out when the crater formed. Boulders ejected during the impact surround the crater.



POSTSCRIPT
For information about NASA and agency programs on the Web, visit: _http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.

Source: HiRISE

Release date Mar 25, 2008
Latitude: 17.30 S
Longitude: 95.50 E




This image of the wall of a graben -- a depressed block of land between two parellel faults -- in Tyrrhena Terra, in Mars' ancient southern highlands, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0914 UTC (4:14 a.m. EST) on February 6, 2008, near 17.3 degrees south latitude, 95.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 35 meters (115 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point.

This image was part of an investigation planned by students in four high schools in Durham, North Carolina. The students are working with the CRISM science team in a project called the Mars Exploration Student Data Teams (MESDT), which is part of NASA’s Mars Public Engagement Program and Arizona State University’s Mars Education Program. Starting with a medium-resolution map of the area, taken as part of CRISM's "multispectral survey" campaign to map Mars in 72 colors at 200 meters (660 feet) per pixel, the students identified a key rock outcrop to test their hypothesis that the irregular depression was formed by Martian volcanism. They provided the coordinates of the target to CRISM's operations team, who took a high-resolution image of the site. The Context Imager (CTX) accompanied CRISM with a 6 meter (20 feet) per pixel, high-resolution image to sharpen the relationship of spectral variations to the underlying surface structures. The Durham students worked with a mentor on the CRISM team to analyze the data, and presented their results at the 39th Lunar and Planetary Science Conference, held in League City, Texas, on March 10-14, 2008.

The upper panel of the image shows the location of the CRISM data and the surrounding, larger CTX image, overlain on an image mosaic taken by the Thermal Emission Imaging System (THEMIS) on Mars Odyssey. The mosaic has been color-coded for elevation using data from the Mars Orbiter Laser Altimeter (MOLA) instrument on the Mars Global Surveyor (MGS) spacecraft. Redder colors indicate higher elevations. The bottom left image shows infrared brightness of the surface measured by CRISM at 2.5, 1.5, and 1.1 micrometers. In the lower right image, the data have been transformed into a map of spectral features indicating the presence of different minerals. Redder areas have a stronger signature of the iron-containing mineral olivine, and green and blue areas show the signature of the mineral pyroxene.

These data sets, acquired over the last ten years, allow increasingly detailed and higher-resolution view of Mars' surface that provide scientists with a variety of measurements to understand Mars' past evolution. The same data provide teenage amateur geologists a fascinating and exciting "field site" at which to exercise the principles of earth science in a real-life, hands-on science investigation.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials — leading to new understanding of the climate.

Credit: NASA/JPL/JHUAPL/Durham Academy

Source: CRISM