Strange meandering ridge amidst Martian glaciers

Overview map

Strange meandering ridge in glacier country

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 21, 2023 by the high resolution camera on Mars Reconnaissence Orbiter (MRO). Its focus is the meandering ridge in the center of the picture, which the scientists intentially describe vaguely as a “ridged flow-like feature”.

The elevation difference between the high and low points within the picture is about 500 feet, though most of that slope occurs in the lighter terrain on the right. The darker area where the ridge is located has no clear elevation trend, though there are hints of depressions and rises within it.

The yellow dot on the overview map above marks this location, deep within the chaos terrain dubbed Deuteronilus Mensae, on the western end of the 2,000 long northern mid-latitude strip I dub glacier country, because practially every image from there shows glacial features.

To underline this fact, the red and white dots mark previous cool images from 2020 and 2021, with the first showing an eroded glacier and the second glacial ice sheets.

The mesa to the east of this picture rises more than 6,000 feet to its peak, as indicated by the black dot. This is also the highest point for this entire grouping of mesas. All are surrounded by a single large apron of material, likely a mixture of alluvial fill and ice.

What however caused the narrow ridge in the picture above? Is it ice or bedrock? If ice why is it so different than the glacial material that seems to surround it? If bedrock, it suggests it is instead an ancient inverted channel created when that ridge was a canyon through which ice or water flowed, compacting the canyon floor. When the terrain around it eroded away it was more resistent and became a ridge instead.

I have no answer. The colors suggest the ridge is rock, not ice, but that is not conclusive.

The grand Valles Marineris of Mars

The grand canyon of Mars
Click for original image.

Time for another cool image of the grand canyon of Mars, Valles Marineris. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small section of the floor of this gigantic canyon, where orbital data has detected light-toned materials. From the caption:

Many of the Valles Marineris canyons, called chasmata, have kilometer-high, light-toned layered mounds made up of sulfate materials. Ius Chasma, near the western end of Valles Marineris, is an exception.

The light-toned deposits here are thinner and occur along both the floor and walls, as we see in this HiRISE image. Additionally, the sulfates are mixed with other minerals like clays and hydrated silica. Scientists are trying to use the combination of mineralogy, morphology, and stratigraphy to understand how the deposits formed in Ius Chasma and why they differ from those found elsewhere in Valles Marineris.

The picture however gives no sense of the monumental terrain that surrounds it.
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Martian lava that buried a crater

Martian lava flow through crater
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a lava flow that cut through an older 2-mile-wide crater, mostly burying it as it burst through the crater’s southwest and northeast rims. From the caption:

A lava channel extends from the feature and continues 60 kilometers to the northeast, growing deeper along its path. The circular formation is likely an eroded impact crater whose walls have been breached by the lava as it surrounded the rim and then infilled the crater. Alternatively, it could represent the location of a volcanic vent that sourced some of the lavas that formed the channel.

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Mars geology that only makes sense by digging deeper

Not-so baffling Martian geology
Click for original image.

Today’s cool image is a perfect example of why nothing in science research should ever be taken at face value, without digging a bit deeper. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

First an important technical point. Though the electronics unit for one of the camera’s color filters is still not working — causing a blank strip down the center of all black & white images, the camera team has gotten around this problem by inserting in that strip other color filter data, thus creating a complete image as you see to the right. This work-around means that MRO’s capabilities, though showing signs of age, will continue almost as good as before.

As for the image itself, when I first looked at it, I was baffled by the striking contrast between the mottled and rough ground in the lower left, and the almost featureless and smooth terrain everywhere else. Why this sudden transition? What could cause it? That inexplicable contrast demanded I post it as a cool image.
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A seasonal map of the cloudy parts of Mars

Seasonal map of the cloudy parts of Mars
Click for original image.

Though Mars’ very thin atmosphere (1/thousandth that of Earth) is generally clear, it does have clouds that come and go. A project begun in 2022 using citizen scientists to identify these clouds and the seasons they appear the most, dubbed Cloudspotting on Mars, has now published its first paper, available here.

The graph to the left, Figure 9 in the paper, shows two seasonal Mars maps, one indicating the daytime seasonal frequency of clouds and the other their nightime frequency. From the paper:

The seasonal evolution of all clouds as a function of latitude for both daytime and nighttime are shown in Fig. 9. During the clear season until [mid-summer in the northern hemisphere] … there are several regions where clouds occur frequently: in the equatorial region (annotated as 1), at mid-latitudes (2), in the southern polar region (3), and to a lesser extent in the northern polar region [at the start of summer]. From [late fall to mid-autumn in the north], daytime clouds occur primarily at mid-latitudes, but are observed at nearly all latitudes between 70°S and 60°N (4). At night, there is one broad population from 30°S to 30°N (clouds are more frequent in the equatorial region at night), but [in autumn], clouds occur frequently between 30°N and 50°N as well. [In mid-spring] the number of observed nighttime clouds increases in the southern hemisphere, especially near 50°S. There is a strong decrease in the number of peaks just before [the late northern autumn and the late southern sping] at nearly all latitudes except around 50°S and 20°N at night. [Once northern winter arrives], clouds are observed between about 60°S and 60°N as well as both polar regions, although nighttime clouds between 0°N and 30°N occur relatively less frequently.

The low-latitude clouds during the clear season (1), which are observed more frequently at night, occur at high altitudes, 65–80 km during the day and 55–70 km at night; this is the aphelion equatorial mesospheric cloud population studied in depth by Slipski et al. (2022) and in which previous observations have spectrally confirmed CO2-ice.

Martian seasons

The bracketed words indicating seasons above replace the longitudal numbers the scientists use to indicate the seasons, and are used on these two graphs. The figure to the right shows what the longitude numbers represent in the graphs’ X-axis.

The project continues if any of my readers want to join in.

A Martian splash crater in the northern lowland plains

A Martian splash crater
Click for original image.

Cool image time (necessary when there is no real space news to report)! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 29, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “steep crater walls.”

And the interior slopes of this 5-mile-wide unnamed crater are steep, about 600 feet high and descending at a grade of 10 to 13 degrees, getting steeper as you go down. In fact, the floor of the crater itself continues that slope downward to the west until it reaches the base of its western interior wall. For some reason the glacial material within it is piled up higher on its eastern end.

The dark streaks on the crater interior walls are either slope streaks or recurring slope lineae, with the former appearing somewhat randomly and the latter seasonal in nature. Both remain unexplained unique phenomenons of Mars. This new picture was likely a follow-up of a January 2014 MRO picture to see if anything had changed in the past decade.

To my eye it is difficult to detect any changes, but I am not looking at the highest resolution version of the picture. The lack of changes suggests the streaks are seasonal lineae, as both images were taken in the northern spring and the streaks in both appear much the same.
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Scour pits of volcanic Martian ash

Scour pits in volcanic ash
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 16, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team describes this as “clusters of scour pits,” which means the pits here were formed by the prevailing winds, which according to a global analysis of dunes on Mars, is probably blowing from the west to the east at this location.

This image only covers a small section of these scour pits. The full field extends about 20 by 18 miles across, and appears to be the southeastern flank of a mile-high dome. The scour marks could therefore also be evidence of some sagging of this material downhill along that flank.

It is also possible that the flow of the prevailing winds across this southeastern downhill slope is causing the pit formation. Unlike this flank, the rest of this dome is relatively smooth.
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A new global map of the near-surface ice on Mars

Global map of near-surface ice on Mars
Click for interactive map.

A project begun in 2019 to use all the presently available orbital data to compile a global map of the near-surface ice on Mars has now been released that global map, shown by the graphic above, taken from Figure 16.7 from the project’s science paper.

The various areas in blue show the evidence of ice down to about 5 meters, or about 15 feet, with darker blue areas indicated ice at greater depth. The study focused on latitudes below 60 degrees latitude, while also blocking out areas above one kilometer in elevation (as indicated in black on the map above). As the paper noted,
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The icy terrain near one of Starship’s prime candidate landing spots on Mars

The icy terrain near Starship's prime landing spot on Mars
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on August 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The camera team labeled the picture a “terrain sample,” which generally means it was not taken as part of any scientist’s specific research request, but to fill a gap in the schedule so as to maintain the camera’s proper temperature. When the team needs to do this, they try to pick a location in the gap that might have some interesting features. Sometimes such pictures show relatively boring features. Sometimes the results are fascinating.

In this case the location chosen was in the northern lowland plains of Mars, in a region called Amazonis Planitia. At 38 degrees north latitude it is not surprising that the photo shows ice features. All the depressions here appear to have an eroding glacier, while the surrounding plateau resembles an untouched snow field in the very early spring, the snow beginning to sublimate away to leave the top rough and stuccoed. Note too that these depressions are likely not impact craters (they have no upraised rims and many are distorted in shape), but were likely formed by that same sublimation process.
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Perseverance looks ahead, beyond Jezero Crater

Perseverance looks ahead, beyond Jezero Crater
Click for original image.

Overview map
Click for interactive map.

Cool image time! The panorama above, enhanced and annotated to post here, was taken on October 21, 2023 by one of the navigation cameras on the Mars rover Perseverance. As shown on the overview map to the right, it looks to the west, at the gap in the rim of Jezero crater, dubbed Neretva Vallis, through which the delta in the crater had once poured.

The blue dot marks the location of Perseverance. The green dot marks the location of Ingenuity, which suggests it is visible within the panorama. I have indicated two features on the panorama that could be the helicopter, but the resolution of this navigation camera image is not good enough to determine with certainty if either is the helicopter or simply a rock.

Beyond the gap can be seen several small mountains, a hint at the generally rough terrain that sits to the west of Jezero that Perseverance will eventually enter and explore. This region is also an area where orbital images suggest a wide variety of minerals, making it a potentially valuable mining location for future Martian settlers.

A low mid-latitude crater on Mars apparently filled to overflowing with ice

ice filling a Martian crater to overflowing
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a steep 1,000-foot-high cliff with what appears to be extensive glacial material at its base.

The many layers all suggest past climate cycles, where snow was deposited and the glacier grew, followed by a period when no snow fell and the glacier either shrank or remained unchanged. The terraced nature of the layers near the base of the cliff suggest that with each active cycle less snow was deposited and the glacier grew less.

The latitude is 33 degrees south, which puts it just outside the dry equatorial regions of Mars and inside the mid-latitude region where many such glacial features are found. Its closeness to the tropics however is significant, because by this point we should be seeing a diminishment of such features. Instead, the wider view shows us that the near surface ice in this region is extensive and in fact appears to cover everything.
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The fractured floor of the south Utopia Basin

The fracture floor of South Utopia Basin

Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The central darker strip however comes from a September 27, 2008 image by MRO’s lower resolution context camera, inserted to fill in the blank section where one component on the high resolution camera has failed.

The picture focuses on what the scientists call a “pit interacting with a mound.” The 100-foot-deep pit is one of a very long meandering string of such pits, all of which suggest the existence of an buried river canyon into which debris is sinking. Altogether this particular string runs from several dozen miles, and its interaction with the triangular 300-foot-high mound suggests at first glance that the river that created the canyon did a turn to the left to avoid a large underground mountain, now mostly buried but revealed by its still exposed peak.

As is usual in planetary research, the first glance is often wrong. The overview map below provides a different answer, which says the formation of the aligned pits is related to the formation of the mound itself.
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Erosion revealing ridges on Mars?

Erosion revealing lava dikes on Mars?
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team calls the features here “narrow ridges”, but what makes these criss-crossing ridges interesting is their location within the picture.

They appear only inside the hollows and depressions, as if erosion had stripped out a top layer of softer material to reveal these ridges, made of a harder material. The almost random but straight orientations of the ridges also suggest they formed along faults or cracks, which also suggests we are seeing dikes where lava was pushed up from below.

Whether the eroded softer material is lava or volcanic ash is unclear, though it certainly resembles the ash layers seen in the giant Medusa Fossae Formation ash field on the opposite side of Mars.

As always, a wider look helps clarify things.
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Location of mud volcanoes in Martian chaos terrain suggest past existence of mud lake

Mud volcanoes in the inland sea

Scientists mapping the location of mud volcanoes in chaos terrain in the dry equatorial regions of Mars have found numerous mud volcanoes, adding weight to the theory that an intermittent shallow lake once existed there.

The inset on the overview map to the right indicates the location of those mud volcanoes (of two types) in white and orange dots. What is significant is that none of the volcanoes are found on the mesas within this chaos terrain, only in the low flats below. From the caption:

Both feature types result from sedimentary volcanism – instead of magma upwells and eruptions, wet sediments, and salts reach and breach the surface, forming mounds and flows. Interestingly, these mounds only occur over the chaotic terrain floor materials and not on the mesas (red-shaded areas) they embay. This suggests a material composition link rather than a genesis by regional extensional forces generated by magmatic rises.

The blue areas are where this same science team think an intermittent inland sea once existed. This new data reinforces that hypothesis.

Features that look like mud volcanoes are common in the icy northern lowland plains. Finding them in the dry equatorial regions strengthens the theory that water was once common there. For this reason the scientists are proposing a mission to this location, especially because the possibility of water might increase the chances of discovering past life.

Review of orbital images confirms source of largest Mars quake was not an impact

Location of May quake
The white patches mark the locations on Mars of the largest quakes
detected by InSight. The green dotted patch marks this particular 4.7 quake.

Scientists reviewing images from several different orbiters have confirmed that the source of the largest Mars quake detected by InSight, 4.7 magnitude, was not caused by a meteorite impact and thus proves that movement in the interior of Mars is still occurring.

The quake, which had a magnitude of 4.7 and caused vibrations to reverberate through the planet for at least six hours, was recorded by NASA’s InSight lander on Wednesday 4 May 2022. Because its seismic signal was similar to previous quakes known to be caused by meteoroid impacts, the team believed that this event (dubbed ‘S1222a’) might have been caused by an impact as well, and launched an international search for a fresh crater.

…During its time on Mars, InSight (which was co-designed by the University of Oxford) recorded at least 8 marsquake events caused by meteoroid impacts. The largest two of these formed craters around 150m in diameter. If the S1222a event was formed by an impact, the crater would be expected to be at least 300m in diameter. Each group examined data from their satellites orbiting Mars to look for a new crater, or any other tell-tale signature of an impact (e.g. a dust cloud appearing in the hours after the quake).

After several months of searching, the team announced today that no fresh crater was found.

You can read their paper here. To do the survey, the team used data from the American orbiters Mars Reconnaissance Orbiter and Mars Odyssey, and also enlisted help from scientists controlling the data from Europe’s Mars Express, China’s Tianwen-1, India’s Mangalyaan, and the United Arab Emirates’ Al-Mal.

The results suggest the quake occurred at “a dip-slip fault in the mid-crust, consistent with an origin between 18 and 28 km depth,” as stated in the conclusion of their paper. More analysis is necessary, but this result proves that the Martian interior still active enough to produce relatively large quakes..

More Martian inverted rivers?

More Martian inverted rivers?
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label “branching deposits,” two wiggling ridgelines with other ridges branching off from them.

What caused this? On Mars there are many such meandering ridges, all of which look like rivers that have positive relief, the opposite of what you would expect. The theory is that these weaving ridges were once canyons where either water or ice once flowed, compacting the streambed so that it was more dense than the surrounding terrain. When that terrain eroded away it left that streambed behind, as a raised meandering ridge.

That answer however might not apply here.
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Ancient flood lava on the upper slopes of the solar system’s largest volcano

Ancient flood lava
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

In this one picture can be seen a glimpse of the entire history of the numerous lava eruptions that once dominated Mars when its giant volcanoes were active one to three billion years ago. The three aligned craterlike depressions likely signal the existence of a large lava tube below ground, placed there during an early large eruption, when the volcano was spewing out so much flood lava that such large tubes could form. The smaller meandering surface rills signal later eruptions that carried less flood lava and thus produced a smaller drainage features.

And finally, the rough and cracked appearance of the surface indicates the ancient age of those last eruptions, probably laid down about a billion years ago. Since then, the volcano has been dormant, and the frozen lava here has had time to erode, become roughened, and show signs of slowly wearing away.
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Martian pseudo-frost terrain

Martian pseudo-frost terrain
Click for original image.

Cool image time! It is always dangerous to come to any quick conclusions about what you see from pictures from another planet. The photograph to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what at first glance looks like a surface similar to frosting seen on window panes on Earth in the winter, where water condensation freezes to form crystalline patterns.

Your first glance would be wrong. This terrain is about 120 miles north of the Martian equator, placing inside the dry equatorial regions where no near-surface ice is known to exist. If this geological feature is formed by the same condensation processes that create ice frost, then it must involve the deposition of some other type of material.

The explanation would also have to account for the change in the terrain, from finely patterned on the right to more crystalline on the left.
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Massive landslide in Martian canyon

Massive landslide in Martian canyon
Click for original image.

Cool image time! The picture to the right, cropped, reduced, enhanced, and annotated to post here, was taken on September 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The image shows a gigantic landslide collapse on the southern interior wall of a long meandering canyon on Mars dubbed Bahram Vallis. The collapse was what scientists call a mass wasting event, in which the entire section of cliff wall breaks off and moves downward as a large unit. In this case the falling section, a half mile wide and long, got squeezed near the bottom, piling up rather than flowing out into the canyon floor.

At this particular location the canyon is 2.4 miles wide, with cliff walls about 1,700 feet high. Imagine when this piece broke off: In one instance a giant section of mountain about a half mile long fell about a thousand feet. Even in Mars’ thin atmosphere the sound must have been thunderous.
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Distorted Martian craters

Overview map

Distorted Martian craters
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The white dot on the overview map above marks the location, on the west end of the 2,000-mile-long northern mid-latitude strip I label glacier country because almost every image suggests the presence of ice and glaciers.

Where this crater is located the terrain is shifting from mesas and criss-crossing canyons to the northern lowland plains. Thus, the features that suggest the presence of ice shift from glacial in nature (flowing down hollows and cliffsides or within canyons) to that of a near-surface ice sheet, which acts to distort impact craters and leave large splash aprons around them.

The straight depression cutting into the crater near the center top that is also aligned with craters to the southwest suggests that these craters are either sinkholes into a void created by a fault line, or the impacts all occurred at the same time, as the asteroid broke up while cutting through the Martian atmosphere.

Either could be true. The data is insufficient to determine which.

Enigmatic terrain amid camera problems on Mars Reconnaissance Orbiter

Enigmatic terrain amid MRO camera problems
Click for original image.

Today’s cool image not only shows us some puzzling lava terrain on Mars, it highlights the continuing camera problems on Mars Reconnaissance Orbiter (MRO) that began last month and now appear to be permanent.

The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 29, 2023 by the high resolution camera on MRO. The black strip through the middle of the picture highlights MRO’s ongoing problem, as described by the science team in its monthly download of new MRO high resolution pictures:

The electronics unit for CCD RED4 started to fail in August 2023 and we have not been acquiring images [data] in this central swath of the images. The processing pipelines will be updated to fill this gap with the IR10 data for some products. The 3-color coverage is now reduced in width.

The picture shows the failure of this electronics unit. The color strip is now only about half as wide as normal, with the other half the black strip with no data. As the problem first appeared in July, and remains unresolved, it probably is permanent. Though MRO’s high resolution camera can still produce images, they will be less useful, their center strip blank.

This failure should not be a surprise. In fact, it is remarkable that so little has gone wrong with MRO considering its age. The spacecraft was launched in 2005, entered Mars orbit in 2006, and has been working non-stop now for about seventeen years. Moreover, it was built in the early 2000s, making it almost a quarter century old at this point. How much longer it can survive is an open question, but a lifespan of twenty years is usually the limit for most spacecraft. The Hubble Space Telescope however gives us hope MRO can last longer, as Hubble has now been in orbit for 33 years, and continues to operate.

Despite this data loss, the picture still shows some intriguing and puzzling geology
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Layered ice sheets on Mars?

Overview map

Layered ices sheets on Mars?

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The white spot near the center of the overview map above marks its location, deep inside the 2,000-mile-long region in the northern mid-latitudes I call glacier country, as everything there seems covered with glacial features of some kind. All the features in this picture are smaller than 50 feet high, based on the resolution of the topographical data obtained by Mars Global Surveyor in the 1990s.

What makes this picture interesting are the layers, made most obvious in the terraced mesa in the upper left. Surrounding this mesa for dozens of miles in all directions are similar layered features, all suggesting that the glacial ice sheets that appear to coat this region have either have been sublimating away over time, or when growing grew less with each subsequent growth cycle.

Though both have or are likely happening, the latter most likely explains the terraces, as there is a lot of evidence on the surface of Mars showing that each subsequent growth cycle produced smaller glaciers and ice layers.

From the perspective of future colonists, this picture once again shows that water will readily accessible on Mars, as long as you travel north or south of the equator at least 30 degrees of latitude. This location is at 42 degrees north, and is very typical of this whole region.

Is this the source of the sand for the giant dune sea that surrounds the Martian North Pole?

Overview map

Circling the north pole of Mars is a gigantic dune field dubbed Olympia Undae, with its densest regions (marked in red on the overview map to the right) estimated to be 700 miles long and covering 120 degrees of longitude.

Where does all the sand come from that created this dune ocean? We now have a rough idea. The arrows on the map to the right indicate the direction of the prevailing winds, as recently determined by scientists studying the orientation of dunes. From this it appears that much of the dust comes from the north polar icecap itself, from its lower layers where dust and ice are cemented together. The prevailing winds, especially in the canyons that cut into the icecap, drive that dust out from the lower layers, where it over eons has piled up in that circular ocean of sand.

The white cross marks the location of today’s cool image, an attempt by scientists to photograph at high resolution one of the sources of this sand, on the edge of the icecap.
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The global wind patterns on Mars, determined by the orientation of dunes

Mars global wind patterns

Wind patterns at the Martina North Pole

Scientists have now roughly determined the global wind patterns on Mars, based on the orientation of one type of crescent-shaped dune called barchan dunes.

The global map above and the north pole map to the right come from figure 2 of the paper. The colored letters indicate the location of additional close-up images. On the polar map Olympia Undae is Mars’ largest dune field. From the abstract:

Crescent-shaped sand dunes are prevalent across the deserts of Mars. Here, we use the physical relationship between the shape of these dunes and the winds that form them to infer the directions of surface winds on Mars on a global scale. We find that dunes typically adhere to the global circulation patterns of Mars’ atmosphere, and that local topographic winds are mostly important in areas with high topographic roughness such as inside deep impact craters. Our global wind map can serve to calibrate numerical climate models, which in turn can help us learn about the recent and modern-day climate of Mars.

The arrows on both maps indicate the direction of the prevailing winds. This data will also help clarify the orientation of many surface features seen by Mars Reconnaissance Orbiter’s high resolution camera. This data also helps explain why the lander InSight never got a burst of wind to clear the dust from its solar panels, while the rovers Spirit and Opportunity did. The rovers were located in regions with clear prevailing winds. InSight was not.

The base of the long and deep south rim of Valles Marineris

Overview map

The base of southern slope of Valles Marineris
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), showing the very bottom section of the long and endlessly deep south slopes of Valles Marineris, the largest known canyon in the solar system.

The many layers here are likely evidence of repeated volcanic flood lava events, over several billion years, after which the canyon formed.

On the overview map above the black dot in the southeast section of the area of the canyon dubbed Melas marks this location. The picture’s northeast corner is essentially the floor of Valles Marineris. From this point the elevation gain to the southwest corner of the picture 3.5 miles away is about 3,300 feet.

The rim itself however is far far higher, about fifty miles farther to the southwest and climbing about 22,000 feet more. Along those fifty miles you’d have to also climb over two intervening mountain ranges, one about 4,000 feet high and the second about 6,000 feet high.

Valles Marineris is big, so big it is hard to imagine a canyon this size. It makes many moutain ranges on Earth seem small.

A mountain buried by lava on Mars

A mountain buried by lava on Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 6, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

This 500-to-600-foot-high hill represents what is likely the top of a much larger mountain, now buried by the flood lava that surrounds it. The edge of that flood lava can be seen best along the base of the hill’s northern slope, where this now hardened lava had washed up against that slope.

That this Martian mountain is very old can be discerned from two features. One, it had to have been there when the lava flowed, and scientists estimate these lava flows are at least one billion years old. Second, peak’s rounded shape and eroded edges (showing terraced layers) suggest it has been here for far longer, allowing Mars’ thin atmosphere and climate to weather it down.
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Almost all of Mars’ geological mysteries in one spot

Almost all of Mars' geological history in one spot

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The scientists label it “Mesas in shallow trough,” but that is only describes a small part of what can be seen here, as I interpret it.

The picture itself shows a small portion of the floor of an unnamed 32-mile-wide crater, with the crater’s southeast interior rim beginning its rise in the lower right. First, note the meandering hollow in the upper left, suggesting some past flow. Second, note the pattern of small ridges on the flat crater floor, suggesting some past drying process that left cracks that later filled with material that formed the ridges at a later time. Third, the mesas themselves suggest chaos terrain, often formed on Mars in connection with glacial flows. Fourth, note that the trough which holds the mesas is on the edge of the crater floor, suggesting the trough and mesas mark the erosion that once occurred at the edge of some material, possibly ice, that once filled that floor.

The trough and small meander also signify something far larger that can only be seen when we zoom out.
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Strange wormlike tube features on slopes of Martian shield volcano

Strange tubes on Mars
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on June 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label the strange tubelike features that are scattered throughout this picture as “landforms,” which is correctly vague because their origin is utterly inexplicable. The ground here is on the eastern slope of a small 20-mile-wide very flat shield volcano located about 150 miles northwest of the giant volcano Ascraeus Mons. The dark wind streaks point down that grade to the east, away from the shield volcano’s peak about 1,000 feet away. (If you look at the full image this indistinct peak is at dead center, with a linear depression (the volcano’s vent) beginning there and heading to the northeast for about four miles.)

Why these many tubes are all oriented in a northwest-southwest direction, at right angles to the slope, is baffling, especially because they hold to that same orientation all across the shield volcano, no matter the downward direction of the slope.
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A close-up of the giant crack that almost splits Mars

A close-up of the crack that splits Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 28, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The intended science focus of the image is likely the floor of this canyon on the lower right, showing what appears to be a patch of uprised topography surrounded by what looks like glacial debris, which at this latitude of 39 degrees north is expected on Mars.

The grade at this location is downhill to the southwest, so if this is a glacier it is flowing in that direction.

The cliff is about 3,000 feet high, dropping that distance in about a mile and a half. Thus, this is only slightly less steep than the very steep cliff wall of the caldera of Olympus Mons, highlighted as a cool image two days ago.

What makes this canyon interesting — besides its spectacular scenery — is its larger context, recognized when one looks at this location from afar and thus sees how it shaped a vast portion of the global surface of Mars.
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Visible ice layers in a crater in the lower mid-latitudes of Mars?

Visible ice layers in the low-mid-latitudes of Mars?
Click for original image. For the original color image, go here.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what appear to be horizontal layers in the inner wall of a small one-mile-wide and 150-foot deep unnamed crater on Mars. I have included the color version below, zoomed in to make those layers and their colors very clear.

As I have not contacted the scientists who requested this picture, I can only guess at its purpose. My guess however relates to those horizontal blue layers, reminiscent of the ice layers seen in Martian scarps at the high latitudes at about 50 to 55 degrees.

Normally it is rare to see horizontal layers like this in craters on Mars. Instead, what you usually see are downward-pointing gullies along with drainage and avalanche-type patterns, though the latter two might not be formed by either drainage or avalanches.

In this case these horizontal layers are clear and pronounced, making this crater a possibly important and somewhat unique find, based on its location.
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