Excavating Water-Rich Rocks

The large 25 km-diameter crater in the foreground of this High Resolution Stereo Camera (HRSC) perspective view has excavated rocks which have been altered by groundwater in the crust before the impact occurred. Using OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer) on ESA's Mars Express and CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on NASA's Mars Reconnaissance Orbiter (MRO), scientists have identified hydrated minerals in the central mound of the crater, on the crater walls and on the large ejecta blanket around the crater. Hydrated minerals were found in 175 locations associated with other nearby craters in the Tyrrhena Terra region of Mars.

Photo credit: Mars Express HRSC, ESA/DLR/FU Berlin (G. Neukum); NASA/MOLA Science Team; D. Loizeau et al.

Note: For more information, see Craters Expose Action of Groundwater Beneath Martian Highlands.

Bright Material along the Floor of a Trough in Noctis Labyrinthus

Many of the troughs (or, rounded depressions) of Noctis Labyrinthus contain bright, sometimes layered, materials. Noctis Labyrinthus is located on the far western end of the large canyon system Valles Marineris. To the west lie the volcanoes of Tharsis.

This HiRISE image shows an example of the bright material commonly found along the floors of some of the Noctis troughs. Spectral data from the CRISM instrument, also onboard the MRO spacecraft, indicate the bright material is hydrated (i.e., contains water). The hydrated material may have formed when water upwelled into the low-lying depression or when ice within the trough melted due to heating from volcanic activity.

An earlier image taken of this same location will now be combined with this new image to produce a stereo anaglyph. The stereo should allow scientists to understand the relationship between the bright material and the darker rocks that make up the trough floor.

This is a stereo pair with ESP_017399_1680.

Photo credit: NASA/JPL/University of Arizona

Pluvo Point

This image near Mars' North Pole was a public image suggestion, with the following rationale: "My three year old son has dubbed this white smudge 'Pluvo Point', he thinks 'we should take a picture of it to learn about how snow and ice comes down on Mars.'"

Although we can clearly see the bright area in this image, it isn't due to frost or ice at this time of year (early summer), and doesn't have the relatively blue color expected for frost. So, what does create the "white smudge"?

The image shows a typical region of northern plains covered by polygons and boulders. There are dark areas in low spots that are probably due to windblown dark sand. Where the sand is most abundant, it forms the dunes seen near the top and bottom of this image. The "white smudge" appears to be a region with relatively little dark sand. It isn't actually white, but it is brighter than other nearby regions. These could be low hills where the sand doesn't collect.

Photo credit: NASA/JPL/University of Arizona

Note: This site is located in Vastitas Borealis to the south of Gemini Scopuli; the closest named feature is Inuvik Crater, which is to the north.

Danielson and Kalocsa Craters

High-Resolution Stereo Camera (HRSC) nadir and color channel data taken on 19 June 2011 by ESA’s Mars Express have been combined to form a natural-color view of the Danielson and Kalocsa craters and their environment in the Arabia Terra region. Centered at around 7°N and 353°E, this image has a ground resolution of about 26 m per pixel. The image shows the yardangs bisected by the darker dune field in Danielson Crater.

Photo credit: ESA/DLR/FU Berlin (G. Neukum)

Note: Danielson crater is the impact crater on the right.

Near the Mouth of Morava Valles

Morava Valles drained Ladon Basin and discharged towards the large regions of chaotic terrain near the head of Ares Vallis.

Because the valley emerges full bore from Ladon Basin (much like the Niagara River emerges from Lake Erie on the Earth), it has been hypothesized that it was formed when a lake overflowed the basin.

There are numerous valleys, including the large Ladon Valles, that end along the margin of Ladon Basin. Some of the outcrops visible in this image and elsewhere in the basin show evidence of layering due to deposition of sediments.

Comparison of the nature and extent of layers exposed here and elsewhere around Ladon basin should help to constrain their origin, by water flow or other processes.

Photo credit: NASA/JPL/University of Arizona

Landforms in Cerberus Fossae

The landforms in this observation are quite diverse, with a segment of the Cerberus Fossae (a deep trough extending east-west) and surrounding terrain that has been eroded by some fluid, either water or lava.

There are many boulders in places, either on steep slopes or excavated by impact craters. The high hills are islands of older terrain surrounded by younger lavas.

Be sure to check out the stereo anaglyph.

This is a stereo pair with ESP_026712_1960.

Photo credit: NASA/JPL/University of Arizona

Note: I have modified this title from "Landforms Near Grjotá Valles" to Landforms in "Cerberus Fossae." Grjotá Valles is some distance off to the east from the location in the above image. This site is actually in the heart of Cerberus Fossae, hence the title change.

Streamlined Hills in Elysium Planitia

This observation was taken to investigate the topography of hills that were eroded by floods of water or lava. In many locations near here it is clear that the last fluid to flow through the region was lava.

Clear margins of lava flows are visible as well as lava textures on the channel floor. In this location, the cover of wind-blown sand and the effect of many small impact craters has erased such obvious indicators of lava. This is likely because the lava coating is thin and can be easily erased.

However, it is also possible that no lava passed through this location. Further investigation of these data should help us better understand the role of water and lava in changing the Martian landscape.

This is a stereo pair with ESP_025802_1960.

Photo credit: NASA/JPL/University of Arizona

Note: This hill is located in Phlegra Dorsa in the immediate vicinity of Grjotá Valles.

Different Materials Exposed along a Wallrock Slope in Coprates Chasma

This image shows several kilometers of topography exposed along the wallrock within Coprates Chasma. Higher topography is towards the bottom of the image while the floor of Coprates Chasma is visible at the top of the image.

There are patches of brighter materials exposed within the wallrock and along the chasma floor. The bright massive rocks exposed in the wallrock likely represent weathered rocks that have altered to this brighter material.

Lower down the wallrock and along the chasma floor, the brighter material appears layered and could represent sediments deposited within the chasma when water or ice may have existed here. The image also shows finer material composed of eroded wallrock and aeolian debris that is mass wasting downslope.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located in far eastern Coprates Chasma, near the entrance of Capri Chasma. The closest named feature is Saravan Crater, to the south.

Sand Ripples West of Aeolis Planum

Landing of the surface of Mars requires extensive planning and imaging reconnaissance. This terrain west of Aeolis Planum is being considered as landing site for a future Mars mission.

The surface is relatively flat with numerous small-scale ridges and mounds. Some of these ridges curve and form the rims of old impact craters, now in various stages of erosion and largely filled with soil. However, most ridges have the appearance of a wind-driven landform called ripples. These features are about 10 yards wide and 100 yards long, and meander slightly but are generally oriented south to north.

Mounds are less distinct, but may also be aeolian (wind derived) in nature. Most of the "freshest" looking crater floors, those seeming least eroded, contain smaller characteristic sand ripples.

All of the craters appear eroded and heavily filled with a soil mantle. Even many of the ripples features appear mantled and smothered by soil. Nevertheless the occurrence of these aeolian bedforms (landforms that are formed by wind blown sand) suggest these surface soils are comprised of loose fine-grained regolith (rocks and fine rock fragments), which the wind has been able to move and organize.

Very few rocks or boulders are seen and those that are seen are largely limited to ejecta around some of the fresher appearing and larger craters. Although still heavily eroded and mantled, these rocky craters indicate more cohesive material such as bedrock or partially-cemented regolith exists beneath the loose soil cover. The absence of widely distributed rocks ejected from craters may suggest this area has experienced extensive, possibly ongoing, accumulation of soil, or that the subsurface rocks are weak and easily eroded by wind and windblown sand.

This is a stereo pair with ESP_027003_1790.

Photo credit: NASA/JPL/University of Arizona

Note: This site is located to the north of Aeolis Mensae and to the northeast of Gale Crater, where the Mars Science Laboratory (Curiosity) will be landing in August.

Streamlined Landforms near the Cerberus Fossae

One of the earliest observations of Mars that indicated that water once flowed across its surface was the presence of large streamlined landforms. Such landforms are carved by flowing fluids that erode islands into teardrop shapes.

While wind can also produce streamlined landforms (called yardangs), many features on Mars were clearly produced by a liquid that was confined to the low areas inside channels. There is an ongoing debate about the roles of lava and water in carving these features.

Streamlined forms visible inside channels on the Moon and Mercury must have been carved by lava since there is no plausible way water could have flowed over those bodies. On Mars, the HiRISE team is seeing a pattern where we believe most channels were carved by water but then covered with lava.

Observations like this one help us test the idea that the lava is simply coating a water-carved surface.

Photo credit: NASA/JPL/University of Arizona

Note: This site is located to the east of the southern-half of the Tartarus Montes chain.

Breccia with Large Clasts in Candor Chasma

In this beautiful image there appears to be a breccia layer, or a layer composed of rock fragments embedded in a finer material. This particular breccia is made up of fragments (or "clasts" as they are known to geologists) so large they can be seen by HiRISE.

The breccia layer, seen most easily near the center of this image, seems to be more resistant to erosion than the surrounding material, serving as a caprock to protect the layers beneath it.

The HiRISE team is planning on acquiring another image over this area in order to create a stereo (3-D) pair. This will help scientists better understand the topography and stratigraphy of the area.

This is a stereo pair with ESP_026523_1735.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located in western Candor Chasma to the east of Ceti Mensa.

In the Transition Zone in Deuteronilus Mensae

Nestled between mesas, this image shows the valley floor where eroded rocky and/or soil debris appears to have flowed viscously from the mesa walls across the valley to merge. A leading theory is that ice and snow became entrained with the soil debris as it shed from the mesa. This combined ice-rich debris then flowed slowly downhill. "Rock glaciers" on Earth are an analogous landform that flow viscously like a glacier, lubricated by ice trapped in the pore spaces.

The image shows light-toned viscous debris that overlays a darker toned surface. Both surfaces sport irregular fracture patterns and evidence that substantial erosion has since taken place. The upper viscous-flow surface also contains abundance small, regular polygonal patterns. Such patterns are commonplace in permafrost on Earth, and are typically considered strong evidence for shallow subsurface ice.

Erosion and the formation of small scarps reveal a multitude of layers within the subsurface. Such structure is unusual for a single glacial flow and may indicate episodic glacial advance and retreat. Additionally, the sparse population of rocks on the surface and along the eroded scarps suggest that the debris eroding from the mesas consists largely of soil.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located in Deuteronilus Mensae, about half-way between Lyot Crater to the north and Sinton Crater to the south, in Arabia Terra.

Da Vinci-Mars Design

I don't receive many comments on this blog, and it's extremely rare for me to promote other non-official websites here, but I think readers of Areology will greatly enjoy Da Vinci-Mars Design. This is an art blog by Ludovic Celle about Mars using Kim Stanley Robinson's Mars trilogy as inspiration. The artwork here is very good, and I hope to get through all of Ludo's posts soon. What I have seen so far is very impressive. Please give Ludo your support!

A Trough within Ladon Basin

This image shows an approximately 2-kilometer wide trough within Ladon Basin. This trough, and others around the perimeter of the basin, were probably produced during the gradual sinking of the materials here.

The basin formed during an epoch in Martian history called the Noachian period, and may have harbored a lake based upon the fluvial valleys that flow into it. If a lake once existed here then the trough is a window that could expose any sediments deposited within the lake, making this an exciting image to explore.

Photo credit: NASA/JPL/University of Arizona

Note: Ladon Basin is not a formally named feature on Mars; however, it is located in southwestern Margaritifer Terra. Ladon Valles (the only Martian feature with the Ladon name) looks to have flowed north into the southern end of the impact basin; however, this trough is far to the northwest of that outflow channel.

Expanded Craters on Icy Terrain in Tantalus Fossae

The middle of this image contains a cluster of depressions (craters) with two levels: a small inner crater, surrounded by a shallow depression extending outward from the inner crater.

This image is located at 50 degrees north latitude, where shallow ice has been mapped by the Mars Odyssey spacecraft. MRO has detected newly-formed impact craters in this broad region that exposed shallow ice, and also revealed that it is nearly pure ice.

One interpretation of the expanded craters visible here is that a group of small impacts, probably secondary craters from a much larger primary crater, exposed the clean, shallow ice in this region. Once exposed, the ice is unstable and sublimates (passes directly from ice to gas), and the shallow depressions could gradually expand.

Photo credit: NASA/JPL/University of Arizona

Note: This crater is located in eastern Tantalus Fossae to the northwest of Tempe Terra.

Late Afternoon Shadows at Endeavour Crater

NASA's Mars Rover Opportunity catches its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars.

The rover used the panoramic camera (Pancam) between about 4:30 and 5:00 p.m. local Mars time to record images taken through different filters and combined into this mosaic view.

Most of the component images were recorded during the 2,888th Martian day, or sol, of Opportunity's work on Mars (March 9, 2012). At that time, Opportunity was spending low-solar-energy weeks of the Martian winter at the Greeley Haven outcrop on the Cape York segment of Endeavour's western rim. In order to give the mosaic a rectangular aspect, some small parts of the edges of the mosaic and sky were filled in with parts of an image acquired earlier as part of a 360-degree panorama from the same location.

Opportunity has been studying the western rim of Endeavour Crater since arriving there in August 2011. This crater spans 14 miles (22 kilometers) in diameter, or about the same area as the city of Seattle. This is more than 20 times wider than Victoria Crater, the largest impact crater that Opportunity had previously examined. The interior basin of Endeavour is in the upper half of this view.

The mosaic combines about a dozen images taken through Pancam filters centered on wavelengths of 753 nanometers (near infrared), 535 nanometers (green) and 432 nanometers (violet). The view is presented in false color to make some differences between materials easier to see, such as the dark sandy ripples and dunes on the crater's distant floor.

Photo credit: NASA/JPL-Caltech/Cornell/Arizona State University

Note: For more information, see Dark Shadows on Mars: Scene from Durable NASA Rover.

Monitoring Dune Gullies in Matara Crater

There are landforms called "gullies," consisting of an alcove, channel, and apron, on many large sand dunes on Mars.

Remarkably, we have learned that the gullies form primarily or entirely during seasons when there is carbon dioxide frost on the ground. To understand this better we image key locations multiple times throughout the Martian year.

This image, at 49.5 S latitude, was acquired very near the winter solstice, when shadows are very long in the middle afternoon when MRO passes overhead. Dark sand inside shadows is a challenging scene to image while flying overhead at 3.4 km/sec, but the HiRISE camera has the sensitivity needed to acquire useful images even at the most challenging time of the year.

The subimage shows one of these gullies, hidden in the shadow. Vertical stripes in the image are from electronic noise that is usually hidden by the image signal, but in this case the signal is extremely low.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located in Matara Crater, which is to the southwest of Hellas Planitia in Noachis Terra.

A Youthful Crater in Cydonia Colles

This observation shows a youthful crater with sharp rim and gullied slopes.

Just what makes a Martian crater youthful, in a geologic sense? Very old craters tend to have eroded rims and can have plenty of material that's filled in the floor. Gale Crater, where the Mars Science Laboratory will land this summer, is an example of an ancient, highly eroded crater. By contrast, the crater in this image appears to have experienced much less erosion.

Note that even though a crater might be called "youthful," it can still mean that the crater formed tens of thousands of years ago, if not more. For an example of a truly recent crater, see the 7 meter (about 23 feet) diameter crater in ESP_015989_1835, which we know formed sometime between 2005 and 2010.

Note: the above image is not map-projected, so North is down.

Photo credit: NASA/JPL/University of Arizona

Note: This crater is located in Cydonia Colles, which is located in Acidalia Planitia to the north of Arabia Terra. This crater is an extremely short distance south of Apt Crater.

Advancing Dune in Nili Patera

Back-and-forth blinking of this two-image animation shows movement of a sand dune on Mars. The images are part of a study published by Nature on May 9, 2012, reporting movement of Martian sand dunes at about the same flux (volume per time) as movement of dunes in Antarctica on Earth.

The before-and-after images were taken nearly three Earth years apart by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The scale bar is 50 meters (164 feet). The site is part of a dune field inside the summit caldera of Nili Patera, an ancient volcano, at 8.7 degrees north latitude, 67.3 degrees east longitude.

The images show a dark, rippled sand dune overlying bright-toned rock. They have been "orthorectified," that is, adjusted such that they appear as if viewed from directly overhead. They were then positionally tied together by registering fixed features on the bedrock seen in one image to the same features seen in the other. When the images are blinked back and forth, advance of the dune's lee (downwind) front over the time period of 941 days is clearly seen in the area indicated by the arrow near the lower-left corner. Other arrows indicate places where the margin of the dune has moved. In contrast, the ripples have changed so much that their migration cannot be tracked.

The first image, in which the main body of the dune looks darker due to lighting effects, was taken on October 13, 2007. It is one image product of HiRISE observation PSP_005684_1890. Other image products from the same observation are at http://hirise.lpl.arizona.edu/PSP_005684_1890. The "after" image was taken on May 11, 2010. Other image products from the same HiRISE observation are at http://hirise.lpl.arizona.edu/ESP_017762_1890.

Photo credit: NASA/JPL-Caltech/Univ. of Arizona/JHU-APL

Note: For a similar animation also located at Nili Patera see PIA15680: Ripple Movement on Sand Dune in Nili Patera, Mars. Also, see NASA Spacecraft Detects Changes in Martian Sand Dunes. For an abstract of the Nature article plus additional images, see Science in Motion.

Leaving Greeley Haven

NASA's Mars Exploration Rover Opportunity drove about 12 feet (3.67 meters) on May 8, 2012, after spending 19 weeks working in one place while solar power was too low for driving during the Martian winter. The winter worksite was on the north slope of an outcrop called Greeley Haven. The rover used its rear hazard-avoidance camera after nearly completing the May 8 drive, capturing this view looking back at the Greeley Haven. The dark shape in the foreground is the shadow of Opportunity's solar array. The view is toward the southeast.

Since landing in the Meridiani region of Mars on January 25, 2004, Universal Time and EST (January 24, PST), Opportunity has driven 21.4 miles (34.4 kilometers).

Opportunity and its rover twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit stopped communicating in 2010.

Photo credit: NASA/JPL-Caltech

Note: For more information, see Opportunity Rolling Again After Fifth Mars Winter.