Release date Dec 10, 2007
Latitude: 15.00 S
Longitude: 98.00 E




After a year in Mars orbit, CRISM has taken enough images that the first parts of a global spectral map of Mars are now being released to the Planetary Data System (PDS), NASA's digital library of planetary data.

CRISM's global mapping is called the "multispectral survey." The team uses the word "survey" because a reason for gathering this data set is to search for new sites for targeted observations, high-resolution views of the surface at 18 meters per pixel in 544 colors. Another reason for the multispectral survey is to provide contextual information. Targeted observations have such a large data volume (about 200 megabytes apiece) that only about 1% of Mars can be imaged at CRISM's highest resolution. The multispectral survey is a lower data volume type of observation that fills in the gaps between targeted observations, allowing scientists to better understand their geologic context.

The global map is built from tens of thousands of image strips each about 10 kilometers (6.2 miles) wide and thousands of kilometers long. During the multispectral survey, CRISM returns data from only 72 carefully selected wavelengths that cover absorptions indicative of the mineral groups that CRISM is looking for on Mars. Data volume is further decreased by binning image pixels inside the instrument to a scale of about 200 meters (660 feet) per pixel. The total reduction in data volume per square kilometer is a factor of 700, making the multispectral survey manageable to acquire and transmit to Earth. Once on the ground, the strips of data are mosaicked into maps. The multispectral survey is too large to show the whole planet in a single map, so the map is divided into 1,964 "tiles," each about 300 kilometers (186 miles) across. There are three versions of each tile, processed to progressively greater levels to strip away the obscuring effects of the dusty atmosphere and to highlight mineral variations in surface materials.

This is the second version of tile 750, in which a still-experimental correction for illumination and atmospheric effects has been applied. It shows a part of Mars called Tyrrhena Terra in the ancient, heavily cratered highlands. The colored strips are CRISM multispectral survey data acquired over several months, in which each pixel has a calibrated 72-color spectrum of Mars. A mathematical model of the effects of seasonal variations Mars' atmosphere has been used to correct brightness to how it would appear if each strip was imaged with the same illumination and without an atmosphere. The three wavelengths shown are 2.53, 1.50, and 1.08 micrometers in the red, green, and blue image planes respectively. Compared to data without corrections, strip-to-strip brightness differences have largely been eliminated. The residual bluish color of some areas is due to clouds that were not included in the mathematical model. The gray areas between the strips are from an earlier mosaic of the planet taken by the Thermal Emission Imaging System (THEMIS) instrument on Mars Odyssey, and are included only for context. Ultimately the multispectral survey will cover nearly all of this area.

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/Applied Coherent Technology

Source: CRISM

Release date Dec 12, 2007
Latitude: 15.00 S
Longitude: 98.00 E




After a year in Mars orbit, CRISM has taken enough images to allow the team to release the first parts of a global spectral map of Mars to the Planetary Data System (PDS), NASA's digital library of planetary data.

CRISM's global mapping is called the "multispectral survey." The team uses the word "survey" because a reason for gathering this data set is to search for new sites for targeted observations, high-resolution views of the surface at 18 meters per pixel in 544 colors. Another reason for the multispectral survey is to provide contextual information. Targeted observations have such a large data volume (about 200 megabytes apiece) that only about 1% of Mars can be imaged at CRISM's highest resolution. The multispectral survey is a lower data volume type of observation that fills in the gaps between targeted observations, allowing scientists to better understand their geologic context.

The global map is built from tens of thousands of image strips each about 10 kilometers (6.2 miles) wide and thousands of kilometers long. During the multispectral survey, CRISM returns data from only 72 carefully selected wavelengths that cover absorptions indicative of the mineral groups that CRISM is looking for on Mars. Data volume is further decreased by binning image pixels inside the instrument to a scale of about 200 meters (660 feet) per pixel. The total reduction in data volume per square kilometer is a factor of 700, making the multispectral survey manageable to acquire and transmit to Earth. Once on the ground, the strips of data are mosaicked into maps. The multispectral survey is too large to show the whole planet in a single map, so the map is divided into 1,964 "tiles," each about 300 kilometers (186 miles) across. There are three versions of each tile, processed to progressively greater levels to strip away the obscuring effects of the dusty atmosphere and to highlight mineral variations in surface materials.

This is the third and most processed version of tile 750, showing a part of Mars called Tyrrhena Terra in the ancient, heavily cratered highlands. The colored strips are CRISM multispectral survey data acquired over several months, in which each pixel began as calibrated 72-color spectrum of Mars. An experimental correction for illumination and atmospheric effects was applied to the data, to show how Mars' surface would appear if each strip was imaged with the same illumination and without an atmosphere. Then, the spectrum for each pixel was transformed into a set of "summary parameters," which indicate absorptions showing the presence of different minerals. Detections of the igneous, iron-bearing minerals olivine and pyroxene are shown in the red and blue image planes, respectively. Clay-like minerals called phyllosilicates, which formed when liquid water altered the igneous rocks, are shown in the green image plane. The gray areas between the strips are from an earlier mosaic of the planet taken by the Thermal Emission Imaging System (THEMIS) instrument on Mars Odyssey, and are included for context. Note that most areas imaged by CRISM contain pyroxene, and that olivine-containing rocks are concentrated on smooth deposits that fill some crater floors and the low areas between craters. Phyllosilicate-containing rocks are concentrated in and around small craters, such as the one at 13 degrees south latitude, 97 degrees east longitude. Their concentration in crater materials suggests that they were excavated when the craters formed, from a layer that was buried by the younger, less altered, olivine- and pyroxene-containing rocks.

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/Applied Coherent Technology

Source: CRISM

SAN FRANCISCO - Scrutiny by NASA's newest Mars orbiter is helping scientists learn the stories of some of the weirdest landscapes on Mars, as well as more familiar-looking parts of the Red Planet.

One type of landscape near Mars' south pole is called "cryptic terrain" because it once defied explanation, but new observations bolster and refine recent interpretations of how springtime outbursts of carbon-dioxide gas there sculpt intricate patterns and paint seasonal splotches.


Bright Streaks and Dark Fans

"A lot of Mars looks like Utah, but this is an area that looks nothing like Planet Earth," said Candice Hansen of NASA's Jet Propulsion Laboratory, Pasadena, Calif., deputy principal investigator for the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

In addition to radially branching patterns called "spiders," which had been detected by an earlier Mars orbiter, other intriguing ground textures in the area appear in the new images. "In some places, the channels form patterns more like lace. In others, the texture is reminiscent of lizard skin," Hansen said.

Results from all six instruments on the Mars Reconnaissance Orbiter, which reached Mars last year, are described in dozens of presentations this week by planetary scientists in San Francisco at the fall meeting of the American Geophysical Union.

By taking stereo pictures of a target area from slightly different angles during different orbits, HiRISE can show the surface in three dimensions. Channels found to widen as they run uphill in the cryptic terrain region testify that the channels are cut by a gas, not a liquid.

Earlier evidence for jets of gas active in the region came from fan-shaped blotches appearing seasonally, which scientists interpret as material fallen to the surface downwind of vents where the gas escapes. Some of the fans are dark, others bright. "The dark fans are probably dust, but the exact composition of the brighter fans had remained unknown until now," said Tim Titus of the U.S. Geological Survey's Astrogeology Team, Flagstaff, Ariz.

Observations by the new orbiter's Compact Reconnaissance Imaging Spectrometer for Mars suggest that the bright fans are composed of carbon-dioxide frost. Here's the story researchers now propose: Spring warms the ground under a winter-formed coating of carbon dioxide ice. Thawing at the base of the coating generates carbon-dioxide gas, which carves channels as it pushes its way under the ice to a weak spot where it bursts free. The jet of escaping gas carries dust aloft and also cools so fast from expanding rapidly that a fraction of the carbon dioxide refreezes and falls back to the surface as frost.

The processes creating the cryptic terrain are current events on Mars. Repeated HiRISE observations of the same target area show the downwind fans can form and grow perceptibly in less than five days.

Other new findings from the Mars Reconnaissance Orbiter reveal processes of Martian environments long ago. A team including Chris Okubo of the University of Arizona, Tucson, used stereo HiRISE images to examine layered deposits inside Mars' Candor Chasma, part of Valles Marineris, the largest canyon system in the solar system.

"The high-resolution structural map allowed us to interpret the geological history of the area," Okubo said. "The layers are tilted in a way that tells us they are younger than the canyon." Spectrometer studies of the composition of these deposits had indicated water played a role in their formation, but their age relative to the formation of the canyon had been uncertain. The new findings suggest water was present after the canyon formed.


Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, California

NEWS RELEASE: 2007-146

Source: NASA/JPL - MRO - Press releases

Carbon-Dioxide Frost Settling from Seasonal Outbursts on Mars (Movie)

12.11.07

This movie, constructed by overlaying a time series of images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), shows seasonal changes and unearthly processes that occur in Mars' south polar seasonal frost cap.

Mars' seasonal caps consist of frozen carbon dioxide mixed with smaller amounts of water ice frost and dust. The different composition of Mars' seasonal caps than Earth's seasonal caps (water-ice snow), plus the lower pressure of the Martian atmosphere, inevitably make springtime recession of the seasonal cap different than the snowmelt that characterizes retreat of Earth's seasonal cap. To monitor Mars' seasonal changes, CRISM repeatedly targets specific regions as Mars' seasons change. Results shown here are evidence that as warming carbon-dioxide ice vaporizes, some is trapped under the ice slab from which pressurized outbursts occur. The released gas expands, cools, and some of it refreezes and falls back to the surface as bright fans.

The region shown in this movie, known informally as Manhattan, is located at 86.3 degrees south latitude, 99 degrees east longitude. To represent the content of the spectral images, two versions of the data are shown side-by-side. The left image was constructed from extended visible wavelengths, to look similar to color images from the High Resolution Imaging Science Experiment (HiRISE) camera. The right image is infrared false-color, with red being the reflectance at 1.30 micrometers, green being depth of the water ice absorption centered at 1.5 micrometers, and blue being depth of the carbon dioxide ice absorption centered at 1.435 micrometers. In this color scheme, surfaces with higher water ice content will appear greenish, while bright carbon dioxide ice will appear magenta. Areas covered by dust will appear dark. In both images, north is to the right. The four time steps in the movie were taken at solar longitudes (Ls) ranging from 195 through 226. (Solar longitude is a measure of seasons, where 180 is southern spring equinox and 270 is southern summer solstice.)

The first frame (image FRT00004959, Ls 195) shows a number of spots and dark fan-shaped features, with a higher concentration of spots on a slope in the middle of the scene. The dark fans show multiple directions, generally indicating wind coming out of the east. The second frame (image FRT000049C2, Ls 196) was taken just a few days after the prior one and starts to show color variations in the fans.

The third frame (image FRT00004B45, Ls 199) records appearance of bright (bluish) fans in addition to the dark fans. The bright fans are slightly more bluish in the false-color image at right, indicating enrichment in carbon dioxide ice. The tails of the dark fans are more greenish, indicated a slight enhancement of water ice. The fourth and final frame (image FRT000059E2, Ls 226) shows distinct bright fans that appear magenta in the false-color image, indicating carbon dioxide ice with little evidence of water ice. However the surrounding surface is greenish, suggesting small amounts of water ice contamination. The tails of the dark fans appear to be more greenish in the infrared than the surrounding ice, suggesting a slight enhancement of the water ice contamination. The difference between the directions of dark and bright fans suggests changes in the wind direction, perhaps as part of a diurnal cycle or pattern.

CRISM science team members working with these data believe that they are seeing evidence for a process first proposed based on data from the Thermal Imaging System (THEMIS) instrument on Mars Odyssey. In this hypothesis, sunlight penetrating the ice warms the underling soil and causes carbon dioxide frost to vaporize at its base. At first the gas is trapped under the frost; when it is released, the expanding gas cools and part of it refreezes to form carbon dioxide frost in the magenta-colored fans.

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.

Image Credit: NASA/JPL-Caltech/JHUAPL/USGS

+ See movie

Source: NASA/JPL - MRO - Multimedia

This image shows a portion of the south polar layered deposits near the base. Illumination is from the lower right, and the scene width is 6 kilometers (approximately 3.7 miles).

The south polar layered deposits are an accumulation of layers of mostly water ice and dust, similar in some ways to the ice caps in Greenland and Antarctica. Often, layers near the base of terrestrial ice caps are deformed because of ice flow and because of sliding of the ice on the underlying surface. On Mars, the polar layered deposits are likely frozen to the underlying materials, and thus do not slide. It is also likely too cold for the ice to flow very much.

These basal layers of the south polar layered deposits do show some interesting wavy patterns that may be due either to simple erosion or to some kind of flow and folding, possibly having occurred in the distant past. In the lower right hand corner some layers appear to be truncated against others, possibly indicating what is called an "unconformity," formed when layers are eroded and then new layers are deposited on top.



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 shows wrinkle ridges in Hesperia Planum. Hesperia Planum encompasses a region of over two million square kilometers (over 770,000 square miles) in the southern highlands of Mars. It is located northwest of the Hellas basin and adjacent to Tyrrhena Patera and contains abundant orthogonal and intersecting wrinkle ridges.

Wrinkle ridges are linear to arcuate positive relief features and are often characterized by a broad arch topped with a crenulated ridge. These features have been identified on many planets such as the Moon, Mars, Mercury, and Venus. On Mars, they are many tens to hundreds of kilometers long, tens of kilometers wide, and have a relief of a few hundred meters. They commonly have asymmetrical cross sectional profiles and an offset in elevation on either side of the ridge.

Wrinkle ridges are most commonly believed to form from horizontal compression or shortening of the crust due to faulting and are often found in volcanic plains.



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 close up shows a complexly fractured and grooved section of the south polar layered deposits. Illumination is from the lower right, and the scene is about 600 meters (approximately 650 yards) across.

The south polar layered deposits are an accumulation of mostly water ice and dust, similar in some ways to ice caps like those in Greenland and Antarctica. In this example, the icy, dusty layers are barely visible, obscured by a complex system of ridges and fractures that formed after the layers were deposited. The layers themselves are highlighted by sunlight and look like broad swales underlying the fracturing.

In the upper left of this example, one can see curvature in the layers which may have formed when the ice was flowing or which may have been due to collapse and slumping of some layers sometime after they were deposited but before they were fractured. The exact cause of the fracturing and grooving is unknown.



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 shows rock outcrops in Meridiani Planum, in the area of the landing site of the Mars Exploration Rover, Opportunity. The image is centered on a cluster of buttes, steep-sided erosional remnants protruding from a level plain. There are two broad categories of material in the image: light-toned sedimentary rock and dark-toned material, which is likely wind-blown sand.

The light-toned material was probably deposited as sediments transported by wind or water; Opportunity found outcrops of aeolian (wind-deposited) sandstone, and this may also be the case in the area of this image. The dark areas show ripples formed by material (probably grains of sand eroded from basaltic lava) blowing in the wind.

In the RGB enhanced-color image (which is not what the colors would like to the naked eye), the dark material is relatively blue, while the light rock ranges from pale blue to tan. The pale blue color in some cases may be due to small amounts of basaltic sand overlying relatively tan rock outcrops, but could also be a real difference due to varying composition or cementation of the rock.

The presence of buttes like those at the image center suggests rock layers of varying resistance. Relatively hard, resistant rock on top can armor a patch of weaker material below; this is commonly observed on Earth. Relations like this are found at many sites in the Colorado Plateau (the Four Corners area of the United States), which has been used as an analogue for this region on Mars.



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

Hellas is the deepest impact basin on Mars and perhaps in the Solar System. It is usually difficult to image the floor of Hellas because of atmospheric hazes, but sometimes it clears, as when this image was acquired.

This image shows some of the most complex deformed terrain on Mars. Initially, flat continuous layers of sediment were probably deposited, perhaps in a sea or from air fall. Subsequently the layers were squeezed and deformed into the strange patterns visible here. The layers appear to have bent and flowed rather than just broken via faulting, perhaps because the sediments were wet or rich in ice.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

The sequence of events experienced by araneiform (spider-like) terrain at Mars' south pole are investigated in a series of images acquired through spring and summer in the southern hemisphere.


In subimage 1 (taken from PSP_002532_0935) we zoom in on a single "spider." This is a radially organized collection of channels in the surface, covered by a layer of translucent seasonal carbon dioxide ice. The "date" is Ls = 181.1. (Ls is the way we measure time on Mars: at Ls = 180 the sun passes the equator on its way south; at Ls = 270 it reaches its maximum subsolar latitude and summer begins.)


Subimage 2 (PSP_002850_0935) was acquired at Ls = 195.4. Four dust fans have emerged from the spider's channels. Translucent ice is warmed from below, and evaporates below the seasonal ice layer. The gas finds a weak spot and vents to the top of the ice layer above, carrying dust from the surface along. The dust is blown around by the prevailing wind.


Subimage 3 (PSP_002942_0935) was acquired at Ls = 199.6. Dust is getting trapped in the channels.


Subimage 4 (PSP_003496_0935), acquired at Ls = 226, shows that the wind direction has changed, the existing fans have lengthened, and there are numerous new fans coming from the channels as the overlying ice layer thins.


Subimage 5 (PSP_003641_0935) was taken at Ls = 233.1, when most of the surface frost is gone. The channels are bright because the sun is shining more directly on the walls. A thin lane of dark dust can be seen on the bottom of the largest channels.


Subimage 6 (PSP_005579_0935) was taken at Ls = 325.4, well into southern summer. All seasonal frost is gone. It is clear that channels are carved into the surface, not the seasonal ice. Fans have disappeared in the sense that they no longer contrast with the very surface material that they came from in the first place. The surface material is water-ice cemented dirt covered with a layer ~5 cm deep of desiccated silt-sized dust, which is redistributed every season in this process of fan creation and deposition.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

The south polar region of Mars is covered seasonally with translucent carbon dioxide ice. In the spring gas subliming (evaporating) from the underside of the seasonal layer of ice bursts through weak spots, carrying dust from below with it, to form numerous dust fans aligned in the direction of the prevailing wind.

The dust gets trapped in the shallow grooves on the surface, helping to define the small-scale structure of the surface. The surface texture is reminiscent of lizard skin.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

In this example the channels form a "starburst" pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

Every year seasonal carbon dioxide ice, known to us as "dry ice," covers the poles of Mars. In the south polar region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.

The channels take on many forms. In the subimage shown here the gas from the dry ice has etched wide shallow channels. This region is relatively flat, which may be the reason these channels have a different morphology than the "spiders" seen in more hummocky 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

This caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

There is an enigmatic region near the south pole of Mars known as the "cryptic" terrain. It stays cold in the spring, even as its albedo darkens and the sun rises in the sky.

This region is covered by a layer of translucent seasonal carbon dioxide ice that warms and evaporates from below. As carbon dioxide gas escapes from below the slab of seasonal ice it scours dust from the surface. The gas vents to the surface, where the dust is carried downwind by the prevailing wind.

The channels carved by the escaping gas are often radially organized and are known informally as "spiders."



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the "cryptic terrain," the ice is translucent and sunlight can penetrate through the ice to warm the surface below.

The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is "visible" by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans.

Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

Have you ever found that to describe something you had to go to the dictionary and search for just the right word?

The south polar terrain is so full of unearthly features that we had to visit Mr. Webster to find a suitable term. "Araneiform" means "spider-like". These are channels that are carved in the surface by carbon dioxide gas. We do not have this process on Earth.

The channels are somewhat radially organized and widen and deepen as they converge. In the past we've just refered to them as "spiders." "Isolated araneiform topography" means that our features look like spiders that are not in contact with each other.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

In a region near the south pole of Mars translucent carbon dioxide ice covers the ground seasonally. For the first time we can "see" the translucent ice by the effect it has on the appearance of the surface below.

Dark fans of dust from the surface drape over the top of the seasonal ice. The surface would be the same color as the dust except that the seasonal ice affecting its appearance. Bright bluish streaks are frost that has re-crystallized from the atmosphere.

Sunlight can penetrate through the seasonal layer of translucent ice to warm the ground below. That causes the seasonal ice layer to sublime (evaporate) from the bottom rather than the top.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

The south polar terrain on Mars contains landforms unlike any that we see on Earth, so much that a new vocabulary is required to describe them. The word "araneiform" means "spider-like." There are radially organized channels on Mars that look spider-like, but we don't want to confuse anyone by talking about "spiders" when we really mean "channels," not "bugs."


The first subimage shows an example of "connected araneiform topography," terrain that is filled with spider-like channels whose arms branch and connect to each other. Gas flows through these channels until it encounters a vent, where is escapes out to the atmosphere, carrying dust along with it. The dark dust is blown around by the prevailing wind.


The second subimage shows a different region of the same image where the channels are not radially organized. In this region they form a dense tangled network of tortuous strands. We refer to this as "lace."



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

In a region of the south pole known informally as "Ithaca" numerous fans of dark frost form every spring. HiRISE collected a time lapse series of these images, starting at Ls = 185 and culminating at Ls = 294. "Ls" is the way we measure time on Mars: at Ls = 180 the sun passes the equator on its way south; at Ls = 270 it reaches its maximum subsolar latitude and summer begins.

In the earliest image fans are dark, but small narrow bright streaks can be detected. In the next image, acquired at Ls = 187, just 106 hours later, dramatic differences are apparent. The dark fans are larger and the bright fans are more pronounced and easily detectable. The third image in the sequence shows no bright fans at all.

We believe that the bright streaks are fine frost condensed from the gas exiting the vent. The conditions must be just right for the bright frost to condense.



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 caption is part of a December 2007 AGU presentation "Spring at the South Pole of Mars."

At the very beginning of spring in the southern hemisphere on Mars the ground is covered with a seasonal layer of carbon dioxide ice. In this image there are two lanes of undisturbed ice bordered by two lanes peppered with fans of dark dust.


When we zoom in to the subimage, the fans are seen to be pointed in the same direction, dust carried along by the prevailing wind. The fans seem to emanate from spider-like features.


The second subimage zooms in to full HiRISE resolution to reveal the nature of the "spiders." The arms are channels carved in the surface, blanketed by the seasonl carbon dioxide ice. The seasonal ice, warmed from below, evaporates and the gas is carried along the channels. Wherever a weak spot is found the gas vents to the top of the seasonal ice, carrying along dust from below.


The anaglyph of this spider shows that these channels are deep, deepening and widening as they converge. Spiders like this are often draped over the local topography and often channels get larger as they go uphill. This is consistent with a gas eroding the channels.


A different channel morphology is apparent in the lanes not showing fans. In these regions the channels are dense, more like lace, and are not radially organized. The third subimage shows an example of "lace."



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

These unusual craters were spotted in Arcadia Planitia, which is part of an extensive region of Mars blanketed by a thick layer of bright dust.

Light southeasterly winds during southern spring and summer blow the dust towards the northwest (top left of the picture in the cutout above). The dust is trapped temporarily in the lee of crater rims, both inside the craters and along the outside rims where they form streamers that resemble St. Nick’s beard.



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 surface of Chryse Planitia, near the mouth of several of the giant outflow channels carved by massive floods. At this location the channel is much too large to be seen within a HiRISE image, and this shows an area of level plains near the mouth.

Two geologic units are visible at this site: a relatively dark expanse in the southern part of the image, and a light, slightly higher-standing area along the northern edge. The light unit may be material that has flowed out from below the surface in a process called mud volcanism. However, many aspects of the history of the northern plains of Mars remain uncertain.

A few other prominent features are present. A long trough with aeolian (wind-blown) ripples runs through the eastern part of the image. This feature likely formed by contraction of the surface layer. This must have occurred after the formation of the light material since it cuts through the light unit in the northwest part of the image. There is also a large mound which appears to bury part of the trough, and thus is even younger. Alternatively, two troughs could both terminate at the hill.

Despite the resolution of HiRISE, the nature of this mound is still unclear. It has a rugged surface, which might mean that it has been eroded enough to remove indications of its origin.



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 shows internal layering exposed in a basal section (bottom part) of the polar layered deposits. The south polar layered deposits are composed primarily of water ice with a small amount of dust.

Variations in dust content most likely controls the erosion of the layers. The layers were laid down over a large area near the south pole, probably over the past few million years. They are believed to record recent global climate changes on Mars in much the same way that polar ice in Greenland and Antarctica provide information about varying climatic conditions on Earth.

Several layers appear to be truncated (see subimage) and most likely represent unconformities. Unconformities form when an episode of erosion that removes all or part of a layer is followed by more deposition.



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 shows lightly cratered plains in Elysium Planitia, which is a low-lying area located in the equatorial region of Mars. Part of an extensional (normal) fault system known as the Cerberus Fossae runs through the center of this image.

Elsewhere in Elysium Planitia, the Cerberus Fossae acted as a fissure-vent for erupting flood lavas, but here the geological activity appears to have been predominantly tectonic. Nonetheless, the raised, lobate (tongue-shaped) margin of an ancient lava flow is faintly discernible in the southern part of the image.

Near the center of the image, a few relatively deep depressions, partly filled with dark sand, are visible in the Cerberus Fossae. These are pit craters formed by collapse as normal faulting progressed. The largest pit crater is about 110 meters (360 feet) wide and about 300 meters (980 feet) long. Steep scarps along the perimeters of the pit craters and the linear margins of the Cerberus Fossae provide a cross-sectional view of the near-surface strata. The exposed material is rocky and has the tendency to break into large boulders that tumble downhill as erosion widens the troughs and depressions. A few low hills appear in the northern half of the image; dark streaks etch their flanks. These “dark slope streaks” formed when small avalanches removed a surface layer of bright dust, exposing darker underlying materials.

The different shades of the streaks may reflect their relative ages, with darker slope streaks being fresher features.



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

Pangboche Crater is a very fresh, 11 kilometer (6.8 mile) diameter crater near the summit of Olympus Mons, a large shield volcano that extends 500 km (310 miles) in diameter. Geologically young craters are important to investigate the current cratering rate on Mars. There are multiple lines of evidence that indicate that Pangboche is geologically young.

Pangboche has a very distinct, sharp rim. Over time, crater rims degrade and blend into their surroundings. It has steep walls as indicated by the numerous boulders rolling down the walls. For boulders and material to dislodge from a slope because of gravity alone, slopes need to be rather steep (approximately 30 degrees).

The interior of the crater contains material that likely slumped off the walls during late stages of its formation. The north wall of the crater has material that has not slumped to the floor, instead forming a terrace.

Also noteworthy is the abundance of small craters that surround, but do not occur within, Pangboche. These are mostly secondary craters that formed when ejecta from an impact hit the surface. If the small craters were primary craters (formed from an impactor from space), then they would be expected to be within Pangboche as well. Secondaries commonly occur in clumps as seen here (see subimage, approximately 2 km across). The strong clustering indicates that these craters are secondaries.



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 Dec 21, 2007
Latitude: 12.03 S
Longitude: 312.04 E




This image of the wall of Capri Chasma, in Valles Marineris, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1151 UTC (7:51 a.m. EDT) on October 6, 2007, near 12.03 degrees south latitude, 312.04 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point, and is one of several dozen that CRISM has taken to search for exposed layering in the chasma walls.

Valles Marineris is a large canyon system that extends more than 4,000 kilometers (2,485 miles) covering nearly one-fifth of the planet’s circumference. If it were located on Earth, Valles Marineris would stretch from the California coast to New England and hold a volume of water approximately equal to that held by the Mediterranean Sea. One of several chasmata that comprise Valles Marineris, Capri Chasma is located toward the eastern end of the larger system.

The upper left panel in the montage above reveals the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft’s Thermal Emission Imaging System (THEMIS). The CRISM data are centered on a resistant spur of material roughly 4 kilometers (2.5 miles) long, located below a crater whose floor was eroded away by the chasma’s rim. The upper right panel reveals this spur in infrared false color. Bright streaks emanating downward from the ridge indicate mass wasting of the lighter material that caps the spur.

The lower two images are renderings of data draped over topography without vertical exaggeration. These images provide a view of the spur’s elevation relative to the surrounding terrain – the lower right in infrared false color, the lower left in false color to reveal mineral content. The predominantly blue color of the lower left image shows that the chasma wall rock is rich in pyroxene, a major constituent of basaltic rocks. The reds and greens in the resistant material that comprises the ridge indicate the presence of olivine and clay-like minerals called phyllosilicates. Broad swaths of red, yellow and green indicate mass wasting of this resistant material down the slope of the spur. Occurrence of phyllosilicate in the deep-seated wall rock provides evidence for a very ancient wet environment.

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

Source: CRISM

A wide variety of south polar terrains are on display in this spectacular HiRISE color image. The reddish material in the upper two thirds of the image is the south polar layered deposits (SPLD). These deposits are a stack of layered, dusty water ice. Scientists believe that these layers record previous climatic conditions on Mars, much like terrestrial ice-sheets provide a record of climate change on the Earth.

This image shows the face of one of the many scarps or shallow cliffs that cut into the polar layered deposits. These scarps expose the internal layers within the SPLD. You can see these climate-recording layers in the upper two thirds of the image running from lower-left to upper-right.

The terrain in the lower third of the image is quite different in both appearance and composition. The bright, white-ish material is a thin covering of carbon dioxide ice draped over the flat areas of the SPLD. This covering of carbon dioxide is being eroded away by expanding flat-floored pits. Parts of the floors of these pits show the reddish brown coloring of the underlying polar layered deposits. These pits have eroded the carbon dioxide ice layer to such an extent that only isolated mesas remain today and even these shrink in extent by a few meters each year.

These mesas also have several layers within them, indicting that they likely contain a climatic record, albeit a much shorter one than preserved in the SPLD. Most of the isolated mesas have white-ish tops; however, some (near the foot of the SPLD scarp) have reddish tops. This may either be due to bright carbon dioxide ice thinning to reveal the older (and darker) carbon dioxide ice that makes up the main body of the mesa, or perhaps dust has settled out of the atmosphere to cover the brighter frost. There was a large Martian dust storm earlier this year which could have caused either effect.



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 of the south polar layered deposits (SPLD) shows evidence of multiple episodes of deposition and erosion near the base of those deposits.

The SPLD, like the north polar layered deposits, are thought to contain a record of global climate changes on Mars. The surface of the outcrop shown here slopes generally toward the right. The layering at the bottom of the image is cut off by deposits that partly fill two broad valleys that were previously cut into the SPLD, probably by wind erosion. These more recent deposits appear to cover the flatter, upper part of the SPLD at left, and have also been eroded to expose layering with them.



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 of the south polar layered deposits (SPLD) shows some of the layers cut off against other layers below and right of center. Geologists call this an “angular unconformity” because the layers do not conform to each other across this boundary.

In this case, the angular unconformity was probably caused by erosion of the SPLD followed by deposition of new SPLD on top of the eroded surface, but faulting could also have caused the observed unconformity. Near the unconformity is an impact crater, one of dozens found on the SPLD. The presence of these craters implies that the surface of the SPLD has been relatively stable (i.e., little erosion or deposition) in the past few million years. This is in stark contrast to the north polar layered deposits, on which craters are very rare, implying very recent erosion/deposition.



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 enhanced color image (1.2 kilometers or 0.7 miles across) shows a section of the south polar layered deposits, which are an accumulation of layers consisting mostly of water ice and dust. Perhaps their closest analog on Earth would be the ice caps of Greenland and Antarctica.

This image is particularly interesting because the layers are not flat-lying but rather appear wavy. This appearance could partly be an “illusion” due to erosion after the flat-lying layers were deposited. In that case, the wavy appearance is due to the fact that the layer edges are wavy, going into and out of the plane of the outcrop exposing the layers (here, into and out of the computer screen).

Alternatively, this waviness could be due to deformation of the layers folding caused by flow of the ice. Here, the flow probably occurred long ago since current temperatures are too low to allow the ice to flow at a significant rate.