The nearest hill to China’s Zhurong

Pitted cone near Zhurong
Click for full image.

Cool image time! The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) today released a pair of images the camera took on June 28, 2021 of the nearest pitted cone to China’s Zhurong rover.

The stereo anaglyph to the right, cropped and reduced to post here, allows you, with blue-red 3D glasses, to see the cone in three dimensions. Quite impressive. As noted by Alfred McEwen of the Lunar & Planetary Laboratory in Arizona in his caption,

This image completed a stereo pair of a region just west of where the Zhurong rover landed in southern Utopia Planitia.

The cutout is from a portion of the stereo anaglyph, showing an enigmatic pitted cone. Is this cone composed of sediments or volcanic materials? The sharp bright features surrounding the cone are aeolian (wind-blown) landforms.

According to McEwan, the hill itself is about 200 to 220 feet high, with the pit at its top about 60-65 feet deep.

While McEwan has told me this cone would be his primary target if he was running Zhurong, it appears the Chinese are instead heading south toward the largest nearby crater, and on the way inspecting the parachute, fairing, and heat shield discarded just prior to landing.

The mosaic below from three MRO context camera images provides a wider overview.
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Fractured crater close to the Phoenix lander on Mars

Fractured crater on Mars
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Cool image time! The photo to the right, cropped to post here, was taken on May 3, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a remarkably fractured crater that lies only a few miles to the southeast of where the now-inactive Phoenix lander put down back in 2008, at the very high latitude of 69 degrees north.

Phoenix was purposely sent to this high latitude to find out what the ground and atmosphere was like there. It found the following:

Phoenix’s preliminary science accomplishments advance the goal of studying whether the Martian arctic environment has ever been favorable for microbes. Additional findings include documenting a mildly alkaline soil environment unlike any found by earlier Mars missions; finding small concentrations of salts that could be nutrients for life; discovering perchlorate salt, which has implications for ice and soil properties; and finding calcium carbonate, a marker of effects of liquid water.

Phoenix findings also support the goal of learning the history of water on Mars. These findings include excavating soil above the ice table, revealing at least two distinct types of ice deposits; observing snow descending from clouds; providing a mission-long weather record, with data on temperature, pressure, humidity and wind; observations of haze, clouds, frost and whirlwinds; and coordinating with NASA’s Mars Reconnaissance Orbiter to perform simultaneous ground and orbital observations of Martian weather.

Below is an overview map showing the location of both this crater and the Phoenix lander.
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Ice, lava, quakes, and faults, all in one Martian image

A lot of geology in one picture
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on April 25, 2021. It grabbed my attention because it possibly captures a whole range of Martian geological processes, all in one place, including evidence of quakes, of lava, of faults, and possibly of glaciers.

First, ignore the black rectangle, which is merely a small section of lost data.

The picture itself shows a wide north-south fissure, as indicated by the distinct western cliff and the fainter and less pronounced eastern cliff. This fissure, likely formed along a fault, was created when the crust was pushed and stretched upward by the pressure of underground volcanic magma, part of the long series of eruptions that formed the many similar and parallel north-south fissures south of the shield volcano Alba Mons.

The overview map below illustrates this fissure’s relationship with Alba Mons.
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The wind-swept volcanic ash plains of Mars

Overview map

Cool image time! In Mars’ volcano country lies the planet’s largest ash deposit, dubbed the Medusae Fossae Formation. Scientists believe that this gigantic deposit, with a size comparable to the nation of India, was laid down by muliple volcanic eruptions over several billion years and is the source of most of the dust seen on the Red Planet.

The overview map on the right shows the location of this ash deposit on Mars. The white cross indicates the location of today’s cool image, found below.
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Another “What the heck?” photo from Mars

Isolated clump of mounds on Mars
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The cool image to the right, cropped and reduced to post here, was taken a decade ago, on August 25, 2011, by the context camera on Mars Reconnaissance Orbiter (MRO), It shows a flat plain with a sudden clump of mounds or hills at the center.

This is one of those pictures from Mars which I like to call a “What the heck?” image. What caused the mounds, and why are they found only in this concentrated clump, with the rest of the terrain around them generally flat?

Though the context image was taken a decade ago, no follow-up high resolution images were taken of this area until very recently.

Below is the one recent high resolution image taken by MRO on May 12, 2021, cropped and reduced to show the bottom half of the mound clump as shown by the white box. It makes the mystery even more puzzling.
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Ice-filled craters in Mars’ glacier country?

Craters in Protonilus Mensae
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Today’s cool image returns us to the chaos region dubbed Protonilus Mensae, the middle of three adjacent mensae regions in the northern hemisphere that I like to dub Mars’ glacier country because there is so much evidence of buried ice there.

The photo to the right, cropped to post here, was taken on May 31, 2021 by the high resolution camera of Mars Reconnaissance Orbiter (MRO). Titled “Layered Feature in Crater in Protonilus Mensae,” the section I have posted focuses on several craters, with the one with the central mesa likely the picture’s target. Based on many similar features found in craters in this region, it is somewhat safe to assume that this mesa is made of buried ice.

The overview map below as always provides the context.
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Cracks, chaos, and maybe caves in one place on Mars

Mosaic of Avernus Cavi fissures
Click for higher resolution. Original images found here and here.

Today’s cool image to the right is a mosaic I have made from two images taken by the context camera on Mars Reconnaissance Orbiter (MRO), showing a most intriguing region on Mars dubbed Avernus Cavi, located in the large volcanic plain called Elysium Planitia between the giant volcanoes Elysium Mons and Olympus Mons, a region I like to call Mars’ volcano country.

The mosaic shows in one picture much of the typical terrain in Avernus Cavi. We see many linear depressions or cracks, created when the ground stretched and cracked at weak points. We also see many depressions that suggest sinkholes, places where the surface sagged down because of a void below ground.

The area of knobs and mesas in the picture’s southeast quadrant is very typical Martian chaos terrain, the later result of long term erosion of these cracks and depressions.

The white box shows the area covered by the image below.
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First attempts to map the layered geology of Mars

layers in Jiji Crater on Mars
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Today’s cool image illustrates well the central task of much of today’s geological research on Mars, using the orbital images to try to map out the visible geological layers seen, and figure out if those layers mark over wide regions specific geological epochs, as they do on Earth.

The photo to the right, cropped and reduced to post here, was taken on May 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and featured on July 12th as a captioned image entitled “Layers Blanket a Crater Floor.” From the caption:

This image shows a layered rock formation within Jiji Crater that has eroded into buttes and stair-like layers.

This formation extends west and east. Similar layered rocks are within several craters in Arabia Terra and Meridiani Planum, including [nearby] Sera and Banes craters. The similarities suggest that the same process was forming deposits over a large geographic area long ago. Our image also indicates that much of the formation has eroded away relative to what has remained.

As you can see in the photo, the layers form a neat staircase of terraces descending from the south crater rim to the crater floor. They suggest that once the crater was filled with this material, which over time eroded away.

An image of similar layered buttes and mesas in Sera crater, only about 20 miles away, was featured here on Behind the Black in December 2020 The overview map below shows the relationship between Jiji, Sera, and Banes craters.
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New images from Zhurong on Mars

Zhurong's view north
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China today released three new images from its Zhurong Mars rover, showing that since their last release in late June the rover has traveled about 1,000 feet to the south to reach the parachute and backshell (or entry capsule), both released just before landing.

The image to the right, cropped and reduced to post here, is the color panorama from that release, looking north. According to a translation of the Chinese press release, provided at this Space.com report, the image shows:

“The complete back cover structure after aerodynamic ablation, the attitude control engine diversion hole on the back cover is clearly identifiable,”

Below is an annotated orbital picture of this location taken by Mars Reconnaissance Orbiter (MRO) in mid-June.
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Clashing layers in Mars’ largest canyon

Clashing layers on a mountain slope on Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on May 27, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows the clash of different layers on the western slope of a mountain within Mars’ largest canyon, Valles Marineris.

The scientist have labeled this a “possible angular unconformity.” In geology an unconformity generally refers to a gap in a series of layers, a period when instead of the layers being deposited they are being eroded away, leaving no record for that time period. An angular unconformity adds tilting to the older layers, which after erosion are then covered by new layers that are oriented somewhat differently.

Based on these definitions, what the scientists suspect is that the brighter layers to the left and lower down the mountain are older. After a period of erosion new layers were deposited on top at a different angle, forming the stripe of layers going from center left up to center right.

The swirly nature of the material on the top of the ridge suggests to me that these layers might be volcanic in nature, but that’s a pure uneducated guess. What some scientists do believe (but have not yet conclusively proven) is that the lower older layers are sediments laid down by an ancient lake that once filled the canyon here.

The overview map below provides a wider view and some context.
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Springtime on Martian dunes near the north pole

Dunes near the Martian north pole, in the spring

Cool image time! The photo to the right, rotated and cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on April 27, 2021. It shows a strange scattering of dunes on a flat plain. The red at the top of each dune probably indicates exposed dust and sand. The white fringe is likely either water frost or the leftover mantle of dry ice that is deposited in the polar regions each winter down to 60 degrees latitude, and disappears with the coming of spring, sublimating back into carbon dioxide gas.

There are a lot of puzzles here. The overview map below provides some context, but only some.
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Sublimating scallops on Mars

Giant scallop on Mars
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Today’s cool image, shown in a rotated, cropped, and reduced version to the right, gives us a close-up look at one of the giant scallops found in the high mid-latitudes of the northern lowland plains of Mars, specifically in Utopia Basin north of the landing sites of both Perseverance and Zhurong. In fact, this particular image is only a few miles north of one of my previous cool images, Giant scallops on Mars, posted in December 2019.

The image was taken on February 3, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). While such scallops are not unusual in the mid-latitudes, their formation process is not well understood. As I noted in the 2019 post, ” scientists believe [pdf] the formation process is related to the sublimation of underground ice.”

According to [one hypothesis] scallop formation should be ongoing at the present time. Sublimation of interstitial ice could induce a collapse of material, initially as a small pit, then growing [away from the equator] because of greater solar heating on [that] side. Nearby scallops would coalesce together as can be seen to have occurred.

This hypothesis is not proven, and today’s cool image raises questions about it. Though the bright material at its center suggests exposed ice, supporting the idea that sublimation of ice near the surface created the scallop, the scallop scarps seem more extended and distinct to the south, not the north as this hypothesis proposes. Sunlight should hit the northern scarps more, which suggests they should retreat more instead of the southern scarp.

The overview map below provides the context.
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Paisley terrain on Mars

paisley terrain on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, is actually a somewhat old image from the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was taken more than a decade ago, on December 28, 2010, and featured as a captioned image one month later. I post it now because it was recently featured as MRO’s picture of the day, and thought it deserved a new look. As the caption from 2010, written by planetary scientist Alfred McEwen, noted,

Remember those paisley shirts during the summer of love in 1967? If so, this terrain may look somewhat familiar.

How did this terrain really form? One theory is that it’s a landslide deposit, perhaps associated with draining an ancient lake.

The overview map below might help make sense of this theory.
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Many of Mars’ geological mysteries, all in one photo

Knobs, streaks, and lava channels on Mars
Click for full image.

Today’s cool image is fun because it contains a plethora of Martian mysteries, all packed into a very small space. The photo to the right was taken on April 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have rotated, cropped, and reduced it to post here.

The uncaptioned picture was labeled “Small Channel Winding between Knobs in Tartarus Colles.” The knobs, which can be seen on either side of the thin channel within the canyon, are actually a major Martian puzzle. Tartarus Colles has a lot of them, and planetary geologists are not really sure how they formed. One 2009 paper [pdf] suggested that the cones were formed by the violent interaction of lava and ice. This earlier paper [pdf] hypothesized that both water and lava had to be flowing over the surface at the same time, producing the steam and the energy that popped the lava cones, kind of like the small convection bubbles seen when tomato sauce simmers.

The scientific literature however is not deep, and there appears to be much uncertainty about this conclusion.

The photo however contains other major Martian puzzles.
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Zhurong’s travels during first three weeks on Mars

Zhurong's travels through June 11th
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The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) today released a new image showing the path that China’s rover , Zhurong, has taken from its landing on May 14th through June 11th.

The photo to the right, cropped and reduced to post here, is that photo. If you look close you can see the rover’s track skirting the edge of the bright blast mark put on the surface by the lander’s engines during touchdown. Though my scale bar is approximate, it does show that in those four weeks the rover traveled about 150 to 200 feet. However, half of that distance was crossed in the five days from June 6th to June 11th (as shown by the two different MRO images at these links), which means the pace is picking up.

The rover’s nominal three-month mission ends in mid-August, only two months from now. However, none of us should be surprised if the mission gets extended for as long as the rover continues to function.

A sample of typical but strange Martian northern lowland plain geology

Typical lowland features on Mars
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Cool image time! The photo to the right, rotated, cropped and reduced to post here, was taken on April 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a nice sample of the typical glacial-filled craters found often in the mid-latitudes between 30 to 60 degree latitudes, surrounded by a lot of erosion features representative of these lowland northern plains.

The biggest crater is very symptomatic of what scientists have dubbed concentric crater fill, a feature that they believe reveals that there is buried ice water glaciers here, protected by a thin layer of debris. The apron of brighter material surrounding the crater could be a splash feature created during impact and now more obvious because it has been revealed as sublimation and erosion lowered the terrain nearby.

The location is north of the Cydonia region in Acidalia Planitia, several thousand miles to the northeast of the region where Viking 1 landed in 1976 and Mars Pathfinder landed in 1997, as shown in the overview map below.
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A confused river of ice on Mars

A river of ice on Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on March 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what MRO’s science team labeled a “Landform in Source Region of Harmakhis Vallis.”

They are being very correct and careful with that label. The landform here is quite clearly reminiscent of a glacier, but because they don’t yet have confirmation of its watery nature, as good scientists they can’t call it that.

I however am a mere journalist, so I am free to speculate more wildly. Sure looks like glaciers to me, the ice flowing downhill from the left to the right and flowing around that central mound.

The overview map below gives a wider context, but also makes the behavior of the glaciers here far more puzzling.
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Boxwork in the basement of Mars

Polygon ridges in Hellas Basin
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, shows what resembles closely what in Earth caves are called boxwork, polygonal ridges sticking out from the bedrock and usually indicating cracks filled with harder material that resist erosion.

Taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on March 23, 2021, what makes this boxwork especially interesting is its size and location. On Earth cave boxwork generally ranges from a few inches to a few feet across. Not only do these Martian ridges range from 100 feet to a half mile in length, they are located at the lowest point in Hellas Basin, the basement of Mars. In fact, this spot is as close as you can get to Mars’ Death Valley, as shown by the overview map below.
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China releases more images from Zhurong

Zhurong looking north past its lander
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The new colonial movement: Three weeks after its Mars rover Zhurong rolled off its lander to begin its 90 day mission, China yesterday finally released the first high resolution images taken by the rover.

The images included a 360 degree panorama, taken while the rover was still sitting on the lander, an image of both the rover and lander taken by a mini-camera that was dropped from the bottom of the rover, a picture of some interesting nearby boulders to the east, and a picture looking past the lander looking north.

This last picture is above, reduced and annotated by me. The small flat but distinct hill to the north I think is the nearest pitted cone that could be either a mud or lava volcano. That cone is about 3.75 miles away, and though a very enticing target is probably too far away for Zhurong to reach, unless it survives for years past its planned three-month mission, as did the American rovers Spirit and Opportunity.

The closer small ridges and hills just to its right could be the east and west rims of the nearest large crater, about 650 feet wide with a distorted shape, that is visible in the high resolution orbital images taken by both Tianwen-1 and Mars Reconnaissance Orbiter (MRO). This crater is about 1,600 feet away.

Based on these images it appears that once Zhurong rolled off the lander to the east, it immediately turned to the right to move several feet south, where it turned right again to move several feet to the west until it was just to the west of the lander, where it took the picture above. During that last move it dropped the small camera behind it so that it could take the picture showing both the rover and the lander.

These maneuvers and the rover’s position south of the lander and facing west suggest they are going to head to the west, where there are some nearby smaller craters and other interesting features. Whether they eventually go north, with that pitted cone a long term goal should the rover last longer than its planned mission through the end of August, remains entirely unknown.

Zhurong finally located on Mars

Zhurong as seen by MRO
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Though the Chinese had earlier this week released one image taken by their Mars orbiter, Tianwen-1, showing their rover Zhurong on the surface of Mars, they did not provide any specific location information.

This lack has now been filled by a new high resolution image of Zhurong taken by Mars Reconnaissance Orbiter (MRO) on June 6, 2021. This image, cropped to match the Tianwen-1 image and annotated by me to post here, shows the parachute, entry capsule, heat shield, lander, and rover. I have added white dots to distinguish the rover from the lander, which indicate that since the Tianwen-1 orbital image the rover had moved south about 70 feet, suggesting it has been able to travel on the surface.

What this MRO image provides that the Chinese refused to reveal is the latitude and longitude of that landing site, which in turn tells us that the lander put down about 14 miles to the northwest of its targeted landing spot. The mosaic of MRO context camera images below show this landing spot in context with the surrounding terrain.
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Evidence of past underground water in the Martian equatorial regions?

Mosaic of strange feature
Click here, here, here, and here for full images.

Today’s cool image, to the right, takes us to the equatorial regions of Mars, a region that today appears quite arid and dry based on all the orbital and rover/lander data so far gathered. The photo and its complex geology however provides us a hint that once liquid water did exist here. At least, that is the hypothesis that scientists presently favor, though making it fit this complex geology is not simple or straightforward.

The mosaic to the right is made from four context camera images taken by Mars Reconnaissance Orbiter (MRO). It shows a very complicated series of depressions — one of which vaguely resembles a crater — that appear to have been washed out by some past erosion process, though that process could not have been that simple because of the fissures and cracks that dominate the floor of the circular feature.

I contacted Chris Okubo of the U.S. Geological Survey, who had requested a high resolution image from MRO of a small part of this mosaic, as indicated by the white box, to ask him what we are looking at. His answer was appropriately noncommittal:
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Eroding Martian lava?

Eroding Martian lava?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on April 19, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Requested by Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Arizona, the image was entitled “Enigmatic Terrain in Elysium Planitia.” The image is labeled so because, as Dundas explained,

Flood lava is a key part of the feature, best seen at the north and south ends of the image. What’s unusual is the knobby terrain at the center. … I haven’t yet been able to do a more thorough study of these features, so plenty of puzzles remain!

The higher material in the upper right is likely flood lava. A 2016 paper [pdf] led by Dundas on similar features in Elysium Planitia that were not as knobby found their origin somewhat baffling. The evidence suggested that lava, mud, wind, and ice could all be involved in their formation, but the evidence was also not sufficient to eliminate any possibility.

In the case of today’s image, the explanation might also be any of these possibilities. For example, we might be looking at the erosion of the flood lava, exposing harder knobs of different material that had been there before and had been covered by the lava. Or maybe the knobs are simply the last bits of that layer of flood lava that has not yet eroded away.

As always, the overview map provides some context.
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Mini-volcanoes (mud or lava?) near Zhurong’s Mars landing site

Mosaic of features near Zhurong's planned landing site on Mars
Click here, here, and here for full images.

Cool image time! Though we still do not know exactly where the Chinese Mars rover Zhurong landed on Mars, we have a rough idea based on the latitude and longitude numbers leaked to the Chinese press in October 2020 and were apparently confirmed by photos taken by the Tianwen-1 orbiter soon after reaching Mars. We also know Zhurong’s engineers wanted to land in the northern lowland plains dubbed Utopia Planitia, a region that is relatively flat and thus makes a safe landing spot for their first attempt to reach the surface of Mars.

The mosaic to the right, rotated and reduced to post here, is made from three context camera images taken by Mars Reconnaissance Orbiter (MRO). The white cross on the right edge is essentially Zhurong’s leaked landing spot. The red box indicates the area covered by one of only two photos that China has released that were taken by its Tianwen-1 orbiter.

The white box in the upper left shows the area covered by today’s cool image, shown below.
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Inexplicable ridges north of China’s Mars rover

Wrinkle ridges in Utopia Planitia?
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, shows some unusual geology about 450 miles north of the approximate area where China’s Zhurong rover landed in the northern lowlands of Mars. It was taken on April 14, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

These scattered ridges remind me of wrinkle ridges, formed when the surface of a place shrinks. With less surface area, the extra material needs somewhere to go, and so ridges are forced up at weak points to release the pressure.

Assuming this hand-waving explanation is true, the next question would be: What causes the shrinking? The overview map below might help provide an answer.
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A visit to a crater near the non-face on Mars

Glacial erosion features inside crater
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on March 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It looks down at small six-mile-wide Apt crater in the northern lowland plains of Mars located at about 40 degrees north latitude. The image’s focus were the layers on the crater interior rim as well as the eroded glacial features on the crater’s floor. The color strip suggests [pdf] that the bluish material on the north-facing south interior rim and floor are likely icy, while the tan-colored material seen in the crater’s north half are likely dusty.

While the suggestion of glacial material on the crater’s interior is very typical for many craters in the mid-latitudes, what makes this crater of interest is its location, only a short few miles south of that mesa on Mars that for decades the shallow-minded insisted was a face and proof of an alien Martian civilization.
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The strange flows in Shalbatana Vallis on Mars

Strange flows in Shalbaltana Vallis
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on March 31, 2021, and shows a series of very distinct arrowhead-shaped sloping ridges interspersed with hollows flowing down from the southern cliff face of Shalbatana Vallis, one of the larger long meandering drainages flowing into the northern lowlands of Chryse Planitia and north of Valles Marineris.

This location is at 5 degrees north latitude, so nothing we see in the picture is likely glacial or evidence of ice.

So what are we looking at? My guess is that the parallel ridges show us a hint of the original slope of alluvial fill. In the past canyon’s south rim or cliff either did not exist, or was much smaller. Instead the ground mostly sloped gently downhill from the plateau to the canyon floor.

Scientists believe that in the far past catastrophic floods of water flowed through Shalbatana. If a massive flood of water off that rim came down that slope of alluvial fill, it could have pushed into that fill and created the hollows, washing the fill down into the canyon floor and leaving behind the ridges in between.

The overview maps below provide the geographical context.
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Glacial flows covering a crater on Mars?

Partially covered crater by glacial flows?

Cool image time! The photo to the right, cropped and reduced to post here, was taken on March 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an eroded mound that appears to have flows coming off its north and south slopes that fill the surrounding low spots, including half-covering a nearby crater.

The science team for MRO’s high resolution camera chose this picture as their April 28th picture of the day, noting the following:

The objective of this observation is to examine a crater which seems to be in the process of getting covered by flow from a mound. This image, in Protonilus Mensae, may show us characteristics of the covering material: could it be debris-covered glaciers?

Below is a global map of Mars, with this mound’s location in Protonilus Mensae in the northern mid-latitudes indicated by a black cross.
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Curiosity climbing Mount Sharp

Curiosity as seen by MRO from orbit
Click for full image.

Today’s cool image, to the right and cropped to post here, was taken on April 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Released today by MRO’s science team, it shows the rover Curiosity sitting on top of the 20-foot high rock outcrop the scientists have dubbed Mt. Mercou. The 16,400 foot high Mt. Sharp is to the south, with the rim of Gale Crater about 30 miles to the north.

I have annotated the image to show the rover’s route both before and after the moment when this picture was taken. As the caption at the link notes, the rover is currently working its way up Mt. Mercou, a route that was not initially in their plans, as shown by the wider MRO view below.
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The steep sudden foothill of Olympus Mons

Olympus Mons on Mars

Today’s cool image starts from afar and zooms inward. The elevation map to the right shows Olympus Mons, the largest volcano on Mars and in fact the entire solar system. About 600 miles across, from the edge to its peak this volcano rises about 54,000 feet, with an actual height relative to Mars’ “sea level” of just under 70,000 feet, more than twice as high as Mount Everest on Earth.

The cross-section of this volcano is so large it would cover almost all of France if placed on Earth. As a shield volcano, it was formed by many many volcano flows that laid down many layers of lava, with some in its northwest quadrant thought to be as recent as 2 to 115 million years ago.

Our cool image today is located at the white rectangle at the southeast edge of this volcano, and illustrates how those many lava flows could create such a large shield volcano with such a large cross section.
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Typical but still mysterious gullies in a crater on Mars

Gullies on crater interior wall

Today’s cool image to the right, cropped and reduced to post here, is of a crater in the mid-latitudes of Mars’s cratered southern highlands. The picture was taken on January 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and is actually the only high resolution image ever taken of this crater.

The gullies in the north interior wall of this crater are the reason why this picture was snapped. These gullies are very typical on the pole-facing slopes of mid-latitude Martian craters, and have puzzled scientists since they were first discovered in the late 1990s in images taken by Mars Global Surveyor. Since then, thousands have been found, almost all of which in the 30 to 60 degree mid-latitude bands where glacial features are also found. Most occur on the more shadowed pole-facing interior slopes of the craters, though at higher latitudes they are also found facing the equator.

Since their discovery scientists have puzzled over their cause, which because of their locations favoring colder temperatures suggest some form of seasonal weather factor. The most preferred hypotheses propose some interaction with water ice or dry ice, or are simply dry flows of rocky granular material. None of these hypotheses have been confirmed. Some evidence suggests they are dry flows, no water involved. Other evidence points to the influence of an underground layer of water ice.

The mystery of these gullies is enhanced by by the wider view from MRO’s context camera below, rotated and cropped to post here.
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