Frozen waves of lava on Mars

Frozen waves of lava on Mars

Cool image time! The picture to the right, cropped and reduced to post here, was taken on January 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an area where the ground suddenly transitions from a crazy quilt of criss-crossing hollows and ridgelines to a very flat and smooth plain.

The location is at 21 degrees south latitude, so this is in the dry equatorial regions. Though it has a small resemblance to the chaos terrain that is found in many places on Mars, mostly in the mid-latitudes where glaciers are found, the scale here is too small and the ridges and canyons are not as sharply drawn. While chaos terrain usually forms sharply defined large flat-topped mesas with steep cliffs, here the ridges are small and the slopes to the peaked tops are somewhat gentle.
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One instrument on Mars Reconnaissance Orbiter ends its mission

Because Mars Reconnaissance Orbiter’s (MRO) CRISM instrument needed to be cooled to low temperatures to use infrared wavelengths for detecting underground minerals and ice on Mars, and the cryocoolers have run out of coolant, the science team has shut the instrument down.

In order to study infrared light, which is radiated by warm objects and is invisible to the human eye, CRISM relied on cryocoolers to isolate one of its spectrometers from the warmth of the spacecraft. Three cryocoolers were used in succession, and the last completed its lifecycle in 2017.

All the remaining instruments on MRO, including its two cameras, continue to operate nominally.

In its final task, CRISM produced a global map showing water related minerals on Mars, released last year, and a global map showing iron deposits, to be released later this year.

The breakup of a Martian glacier

The breakup of a Martian glacier
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on January 29, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label a “contact” in the glacier country in the northern mid-latitudes of Mars.

The contact is clearly the region of breakup in the middle of the picture. To the right the surface is whole and very smooth. As we move to the left that surface begins to show cracks and holes until those holes and cracks eliminate that surface entirely, revealing a lower layer that is soft-looking and stippled.

In other words, this is the edge of a glacier, and is the place in which it is breaking up. Unlike Earth glaciers however this breakup process is entirely different.
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The strange terrain in the basement of Mars

Strange terrain inside Hellas Basin
Click for original image.

I’ve posted numerous cool images about the weird and alien terrain found routinely in what is Mars’ death valley, Hellas Basin. Today is no different. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 23, 2023 to fill a gap in the schedule of the high resolution camera on Mars Reconnaissance Orbiter (MRO). Thus, it isn’t linked to any particular research, and its target was chosen by the camera science team almost at random.

What it shows is a strangely striated plain interspersed with rounded mesas and partly buried craters. The shape of the striations suggests that they were formed from wind blowing consistently from the north. This hypothesis is reinforced by the material that seems piled up at the base of the two bottom mesas, as if it was blown there.

Is ice or lava however?
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A spray of small impacts melting Martian ice?

A spray of small impacts melting Martian ice?

Cool image time! The picture to the right, cropped and reduced to post here, was taken on March 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and was taken not as part of any specific research request but by the MRO science team to fill a gap in its schedule while also maintaining the camera’s temperature. Sometimes these somewhat random times show nothing of interest. Sometimes they are fascinating, as in this case.

The photo shows what appear to be a spray of small impacts on an easily melted surface. Imagine spraying hot molten lava on a sheet of ice. Instead of creating a crater with an upraised rim, on impact each droplet would quickly melt a hole.

Did these small impacts all occur at the same time? My guess is yes, based on the overview map below.
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Jumbled floor of ancient Martian channel

Jumbled floor of ancient Martian channel
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

At first glance I thought I was looking at a variety of eroding glacial flows. I was completely wrong. This terrain is located on the floor of 900-mile-long Ares Vallis, thought to have been carved eons ago by some flow, either liquid catastrophic floods or glacial ice, but is now located in the very dry equatorial regions of Mars.

Then what caused these meandering ridges? The overview map below, plus the wider view of MRO’s context camera, provides us more data but little illumination. In fact, both leave us more questions and mysteries.
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The peeling floor of a crater in the southern cratered highlands

Overview map
From Argyre Basin to Hellas Basin is about 7,000 miles.

The peeling floor of a crater in the southern cratered highlands of Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 25, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists labeled this image “Crater fill”, but that hardly suffices. First, the fill appears at first glance to resemble peeling paint. At closer inspection, rather than peeling paint we have instead a collection of ridges vaguely resembling cave rimstone dams that either enclose a blob-shaped region or simply meander about until they reach the crater’s interior rim.

The crater interior itself appears largely filled with material so that its rims are subdued. The location, as indicated by that black dot near the center of the overview map above, marks the location at 49 degrees south latitude, in the middle of the cratered southern highlands of Mars where many craters have strangely eroded interiors.

What makes this crater however more puzzling is that none of the surrounding nearby craters look like this. A context camera image taken March 23, 2019 shows that while some of the nearby craters have what appears to be glacial material in their interiors, none exhibit these meandering ridges. This crater stands unique, for reasons that are utterly unknown.

Are these ridges a manifestation of the glacial material filling the crater? Or are they bedrock sticking up through that glacial debris? Your guess is as good as mine.

The very icy high northern latitudes of Mars

Pedestal crater on Mars
Click for full image.

Today’s cool image to me illustrates how the presence of near surface ice in the high latitudes of the northern lowland plains of Mars helps to produce a very strange and alien terrain.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a typical example of what the scientists have dubbed a “pedestal crater,” where the crater ends up higher than the surrounding terrain because the impact had packed the ground and made it more resistant to erosion.

This theory however does not explain entirely what we see here. That apron mesa surrounding the crater also resembles the kind of splash field that is created when an impact occurs in less dense ice-rich ground. Note too the soft stippled nature of the ground. Wind erosion is not the sole cause of change here.
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A pyramid on Mars

A pyramid on Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on January 21, 2023 by the high resolution camera of Mars Reconnaissance Orbiter (MRO). It shows what the scientists label a “pyramidal mound”, which is I think understating the point somewhat.

This pyramid is almost perfectly square, with two perpendicular ridgelines rising from its corners to meet perfectly at the pyramid’s peak. A similar pyramid mound in the Cydonia region, where the so-called “Face on Mars” was found, caused endless absurd speculations in the 1990s of past Martian civilizations, all of which burst into nothingness when good high resolution images were finally obtained in the 2000s.

But what caused this very symmetrical natural feature?
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Triple crater on Mars

Triple crater on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have labeled simply as a “triple crater,” a very apt description.

What caused this? The most obvious explanation is the arrival almost simultaneously of three pieces. As this asteroid or comet entered the thin Martian atmosphere as a single object, that atmosphere was thick enough to break it into three parts but not enough to destroy it entirely. When it hit the ground, the top piece hit first, with the center and bottom pieces following in sequence, thus partly obscuring the previous hits.

The smaller surrounding craters could either be additional pieces from the bolide, or secondary impacts from ejecta thrown out at impact.
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Weird surface cracking in the Martian northern lowland plains

Weird surface cracks on Mars

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on January 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The picture was simply labeled “Channel-like feature”, which hardly describes this strange terrain.

Apparently a mantle of surface material has covered and filled an ancient east-west channel. That surface material however has since cracked along the edges of that channel as well along its length. The cracks suggest that the material in the channel is moving downhill slowly, cracking along the cliff walls while also being pulled apart to form the north-south cracks.

My regular readers will I think be able to guess what is going on here, but if you can’t, the overview map below will help explain this.
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Exploring the cratered southern highlands of Mars, part 4

Overview map

Gullies in Asimov Crater
Click for full image.

Today is the last part in our four part exploration of the cratered southern highlands of Mars, begun last week. (For the early parts, go here-Part #1, here-Part #2, and here-Part #3.) Though there is no need, new readers should read the first three parts first, in order to get the larger perspective of this final post.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on December 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the eastern main gully descending down into a pit that sits in the north center of 52-mile-wide Asimov Crater, as shown in the inset on the overview map above. (For an MRO high resolution of the western gullies into this pit, see this January 2019 cool image post.)
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Exploring the cratered southern highlands of Mars, part 3

Overview map

Pit and surface in crater
Click for original image.

This is the third part of this week’s series taking a look at some of the strange features in the southern cratered highlands of Mars. In the first part I posted a beautiful image of what appears to be a crater filled to the brim with glacial ice, surrounded by an ice sheet plain. In part two we took a look at the interior of Rabe Crater, which though very nearby does not appear to have obvious glacial features within it at all. What it has instead are deep open air pits and a lot of sand dunes.

Today’s image to the right, cropped, reduced, and sharpened to post here, takes us to the interior of an unnamed 45-mile-wide crater only about 70 miles north of Rabe. The black dot in the inset on overview map above indicates the photo’s location. The picture was taken on January 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Like Rabe, this crater also has many large open-air pits. In the picture one pit, near the lower center of the picture, is surrounded by soft-looking mounds and a strangely swirling textured and uneven terrain that makes up the majority of the crater’s floor.

This picture might help explain what we saw in Rabe. The textured terrain in this unnamed crater could easily be ice-impregnated and now hardened sand dunes. The pit could be where that impregnated ice has sublimated away, leaving behind the dust from those ancient dunes which then forms new sand dunes. In Rabe, the crater floor above its pits looks very similar to this swirling textured surface, suggesting the same process is going on there.

What strengthens this explanation is the many other craters nearby, all indicated by red dots in the overview map above, that also have pits or distorted crater floors. Their proximity suggests that there is an underground ice layer in this region, always at about the same elevation, and each crater impact exposed it. With time that exposed ice, no longer pure but filled with material from the impacts, sublimated partly away, producing the pits as well as ample sand to form sand dunes.

Exploring the cratered southern highlands of Mars, part 2

Overview map

Dune-bedrock contact in Rabe Crater
Click for original image.

Our travels in the cratered southern highlands of Mars continues. Today we visit 67-mile-wide Rabe Crater, as indicated on the overview map above. The picture to the right, cropped and reduced to post here, was taken on January 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Rabe Crater is significant for several reasons. First, it was one of the first places on Mars where sand dunes were identified, by one of the Viking orbiters in the late 1970s [pdf]. Second, the pits and sand in its interior, are unusual and puzzling. The inset on the overview map provides a closeup look at the crater. The yellow mound in the central south of the crater floor is all dunes, which are surrounded by the pit with steep cliffs more than a 1,000 feet high.
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Exploring the cratered southern highlands of Mars, part 1

Overview map of southern cratered highlands of Mars

Glacial filled crater
Click for original image.

Today and for the next three days the cool images that I will post from Mars will explore a region that I have not covered very much in depth, the cratered southern highlands between the giant basins Argyre and Hellas. The map above is an overview of this 7,000-mile-long region, all of which is inside the 30 to 60 degree south latitude band where scientists have found much evidence of buried glaciers. In this region the bulk of that evidence is most obvious inside craters.

The picture to the right, cropped, reduced, and sharpened to post here, was taken on December 21, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a typical example of the kind of glacial feature found. The white cross on the map marks its location, west of the Hellespontus Mountains that form the western rim of Hellas Basin.

Scientists have dubbed this feature concentric crater fill, a purposely vague term because — though it looks like glacial fill — until there is data to confirm it the scientists would quite properly rather not commit themselves. The concentric rings suggest multiple layers, each of which likely marks a different climate cycle in Mars’ geological history.

In this case the glacier features also appear to cover the entire plain surrounding the crater as well as its rim. The small crater to the west is similar, and both give the appearance that the ice sheet that covers them came after the impact, draping itself over everything, with the craters only visible because the ice sheet sags within their interiors.

More crazy features from the cratered highlands to come.

The outermost edge of Mars’ north polar icecap

The outermost edge of Mars' north polar icecap
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 4, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the terminating cliffs of the north pole ice cap of Mars, dubbed Rupes Tenius on this side of the icecap.

At this point the elevation difference of the icecap’s edge from top to bottom is not significant, only about 1,500 feet or so, though this is a very rough estimate. As with all other images of the ice cape’s edge, there are many many layers visible, all indicating a different cycle in the climate history of Mars as its rotational tilt swings from about 11 degrees to 60 degrees over eons.

Moreover, at this point there is likely not that much difference between the terrain on top and the terrain below. Both will be mixed ice and dust and coarse rocks, though the percentages will be shifting towards less ice as we go down.
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A journey into Martian chaos

Overview map of Aram Chaos

With today’s cool image, we shall begin with the overview map, and drill our way down until we get a close look at another example of truly alien Martian terrain, with only a hint of similarity to comparable geology on Earth.

The overview map to the right shows us Aram Chaos, an ancient 170-mile-wide impact crater that has gone through such complex geology that it is difficult, maybe impossible, to unravel it based on data obtained from orbit. As I wrote in a detailed December 2020 post describing the confusing geology of this crater,

The floor of Aram Chaos is a place of great puzzlement to planetary geologists. The geology there is incredibly complex, and includes chaos terrain overlain by several sedimentary layers of sulfate minerals. The chaos terrain is most obvious in the southern part of the crater’s floor. The flat areas near the eastern center are those overlaying sedimentary layers.

When we zoom into the white box we can see a good example of this complexity.
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Sponge terrain on Mars

Sponge terrain 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 January 11, 2023 by the high resolution camera on Mars Reconnaissnace Orbiter (MRO).

The scientists labeled this picture “Rocky Terrain.” Though this describes the overall sense of the full image, it fails to capture correctly the nature of this patch of ground at the center of the picture. As you can see, this patch of spongelike surface starts and ends abruptly. It appears that it is a layer on top of the surrounding terrain that has also been eroded aggressively since its placement.

The many craters on its surface seem to have come later, though as the crater size diminishes it becomes harder to separate the craters from the sponge holes. Moreover, some of the larger craters are distorted in shape, as if the impact hit material that was viscous and could flow somewhat.

The overview map below gives some context, but only some.
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A bubbly cauldron on the surface of Mars

A bubbly cauldron on the surface of Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on December 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a strange terrain of craters and mounds, with all the mounds having pits within them like volcanic calderas. In between the surface has a two-toned stippled look, as if two different materials are in the process of mixing.

My immediate impression was that of the bubbly surface of a vat of tomato sauce simmering. Or maybe the vile mixture created by the witches in Shakespeare’s Macbeth, which as they mix they chant:

First witch:
Round about the cauldron go;
In the poison’d entrails throw.
Toad, that under cold stone
Days and nights has thirty-one
Swelter’d venom sleeping got,
Boil thou first i’ the charmed pot.

ALL:
Double, double toil and trouble;
Fire burn, and cauldron bubble.

Of course, this is not a vat of witch’s brew or tomato sauce. It is the surface of the planet Mars, but an alien surface nonetheless.
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Zhurong: Small polygons on light curved dunes indicate regular atmospheric water interaction

Zhurong's full journey on Mars

A paper published this week in Geophysical Research Letters by the science team for China Zhurong Martian rover has revealed the discovery of small polygon cracks on the surface of the many curved light-colored small dunes found in the region where Zhurong landed, suggesting the possibility of relatively recent water activity between the atmosphere and the dune surfaces.

Those dunes, dubbed transverse aeolian ridges (TARs) by the science team, are the many light curves visible in the labeled Mars Reconnaissance mosaic to the right. The blue arrows indicate Zhurong’s path south from its landing spot at the top and ending near the bottom of the picture after traveling about 1,400 feet.

According to the paper, the TARs were formed by the prevailing winds over many eons, coming first from the north and then from the northwest. The edges of the ridges, being smaller, are pushed ahead quicker, thus creating the curved shape. The polygons were small, never larger than 4 inches in size, with five to six sides. The scientists theorize that they were formed when atmospheric water interacted with the dune crust, causing fractures “due to temperature/moisture changes or deliquescence/dehydration cycling of salts”. This process could be slow or fast, and could actually be occurring in relatively recent times, as the scientists say it requires only a little water in the atmosphere.

More likely however we are seeing evidence of water from the past, from tens of thousands to several million years ago.

Zhurong meanwhile remains in hibernation, and might never come out of that condition. Orbital images indicate that its solar panels are dust-covered, the result of the heavy winter dust storm season. The project team however is hopeful that with time and the arrival of Martian summer the dust will be blown off and they can reactivate the rover. This hope however entirely depends on the arrival of a dust devil acoss the top of Zhurong, a random event that cannot be predicted. With both the Spirit and Opportunity rovers, such events happened regularly, allowing those missions to last years instead of only 90 days. With InSight it never happened, and the lander died after two-plus years on Mars.

Zhurong’s future fate thus remains unknown, but not promising at this moment.

Mars’ largest mountain region

Mars' largest mountain region
Click for original image.

The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on September 21, 2015 by the context camera on Mars Reconnaissance Orbiter (MRO). I originally was going to post a high resolution image of some of these mountains, taken on January 1, 2023 that showed some slope streaks, but quickly realized that a wider view of this mountain region was a much more interesting story.

This picture covers an area about 50 by 50 miles. As you can see, it is endless series of random hills ridges and peaks, with only a vague hint of a northeast to southwest alignment. Ground travel through this region would be slow and twisty, immediately reminding me of my many trips to West Virginia, where the hills and valleys are almost as random and never ending.

The overview map below however suggests the scale of this region exceeds West Virginia many times over.
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A Martian crater with a surface pattern that resembles hanging draperies

A Martian crater with a surface pattern like hanging draperies

Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on January 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what the scientists label a “streak-spoke pattern” inside the crater. To my eye, the pattern more resembles hanging draperies, neatly tied near the top and then pulled apart as they descend to the ground.

This photo was a follow-up to a previous picture by MRO on February 4, 2008, more than seven Martian years ago, to see if there had been any identifiable changes in that time. Both images were taken in springtime, and despite the passage of time, the 2023 image shows no obvious changes from the 2008 photo.

What caused this distinct pattern? The first guess would be the wind, except if so shouldn’t there have been some change over seven Martian years?
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Ancient Martian landslides

Ancient Martian landslides
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on December 23, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image was labeled “Landslides in Orson Welles Crater” because the full photo shows at least two large and obvious slides, with the biggest shown to the right.

These avalanches are likely ancient because both have craters on them suggesting the material has not moved for a very long time. Yet when both flowed they did so almost like mud, the material moving downhill almost in a single blobby mass. Both have this look, as do many Martian landslides, which I think is why the scientists usually label them mass wasting events.
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Where the flood lava of two gigantic Martian volcanoes meet

Where the flood lava of two gigantic Martian volcanoes meet
Click for original image.

Today’s cool image illustrates once again the importance of looking not simply at the picture but at the surrounding larger context in order to understand the Martian features within the photograph.

The photo to the left, cropped, reduced, and sharpened to post here, was taken on January 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is at 26 north latitude, so it is in the dry equatorial regions. It shows what appears to be a large Martian flood lava plain, with at least two different flood lava events appearing to flow to the northeast, with the second only partly covering the first.

From this high resolution image it seemed probable that the source of the flow was from the southwest, an assumption that at first glance is strengthened by the overview map below.
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Confused glaciers in a Martian crater

Confused glaciers in a Martian crater
Click for original image.

Cool image time. The picture to the right, cropped to post here, was taken on February 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a strangely blobby crater in the northern mid-latitudes where glacial features are frequently found inside craters.

In this case however the glacier seems very confused. As this is in the northern hemisphere, you would expect glacial material to survive on the north-facing southern interior slopes of the crater, where there is year-round less sunlight. The mottled eroded terrain in the south part of the crater floor suggests this. However, the crater also clearly has a terraced glacier on its south-facing northern interior slopes.

Why has the glacial material survived in both places, but not in the center of the crater?

In addition, there is that strange roughly circular feature attached to the south side of the crater. What formed it? Is it a glacier on the plains surrounding the crater? Or are we looking at volcanic material?

This crater is also unique. The crater just to its southwest (partly seen in the cropped image above), is a much more typical glacial-filled mid-latitude crater, its interior material more evenly distributed and its circular rim only slightly distorted.
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A half-mile high Martian cliff on the verge of collapse

A half-mile Martian cliff on the verge of collapse
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on December 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows erosion gullies coming down off a mountain side, just north of a massive cliff that I estimate to be around 2,000 to 3,000 feet high.

Note the north-south-trending cracks. These suggest that this entire half-mile-high cliff face is slumping downward, cracking as it does so. The cracks at the start of the high flat-topped thumb-shaped mesa near the image bottom are especially intriguing. They suggest that this entire mesa might eventually separate and give way.

There is a specific reason this cliff face is slumping, as shown in the overview map below.
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A verde valley on Mars

A verde valley on Mars
Click for original image.

In the southwest where I live, a valley dubbed “verde” (which means “green” in Spanish) is generally a place with a somewhat persistent river with lots of lush plant life. The Verde Valley in Arizona is the perfect example, with “close to 80% of the valley’s land … national forest.”

On Mars there is also a verde valley, but the name is not descriptive in the least. The picture to the right, rotated, cropped, and reduced to post here, was taken on January 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows one section of the Martian Verde Vallis, draining south to north.

The dark rippled patches inside this shallow canyon are sand dunes. In fact, though MRO has not taken many high resolution images of Verde Vallis, every one shows the valley with further patches of ripple dunes. See for example this image of a section of the valley just a bit farther north.
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The ubiquitous presence of ice in the Martian mid-latitudes

Ice in the Martian mid-latitudes
Click for original image.

Cool image time! The picture to the right, rotated, cropped, rotated, and sharpened to post here, was taken on November 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “crater with mesa”, it gives us another example of the presence of glacial ice in the mid-latitudes of Mars.

That mesa is what planetary scientists have labeled “concentric crater fill,” a glacial feature found in numerous craters throughout the mid-latitude bands from 30 to 60 degrees latitude. The ground in the terrain surrounding the crater could be also be impregnated with ice, but based on the location as shown in the overview map below, it is just as likely to be lava.

In fact, the location of this particular crater illustrates why concentric crater fill might become the best source of ice for future colonists.
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Endless ripple dunes in Mars’ third largest impact basin

Ripple dunes in Mars' third biggest impact basin
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on November 30, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The section cropped shows only a small portion of the endless ripple dunes seen in this area. The color strip provides us some interesting other details as well as mysteries. The orange indicates dust on the ridges as well as the higher terrain near the center of the picture. The green in the hollows as well as to the east and west suggests coarser materials that have settled in lower elevations. This supposition is reinforced by the orange area near the bottom of the picture where the ripples have mostly dissipated. This is a high spot, and we appear to be looking at a dusty surface. (This impression is clearer in the full image.)

The latitude is high, 48 degrees south, but as far as I know orbital images have not found a lot of ice evidence in this part of Mars.
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Geological evidence of past glacier found in Mars’ dry equatorial regions

Overview map

Scientists have uncovered geological evidence of a past glacier in westernmost end of the giant Martian canyon Valles Marineris, right at the point where it transitions into the complex chaos region dubbed Noctis Labyrinthus. The white dot on the map to the right indicates the location.

The surface feature identified as a “relict glacier” is one of many light-toned deposits (LTDs) found in the region. Typically, LTDs consist mainly of light-colored sulfate salts, but this deposit also shows many of the features of a glacier, including crevasse fields and moraine bands. The glacier is estimated to be 6 kilometers long and up to 4 kilometers wide, with a surface elevation ranging from +1.3 to +1.7 kilometers. This discovery suggests that Mars’ recent history may have been more watery than previously thought, which could have implications for understanding the planet’s habitability.

What we’ve found is not ice, but a salt deposit with the detailed morphologic features of a glacier. What we think happened here is that salt formed on top of a glacier while preserving the shape of the ice below, down to details like crevasse fields and moraine bands,” said Dr. Pascal Lee, a planetary scientist with the SETI Institute and the Mars Institute, and the lead author of the study. [emphasis mine]

You can read the paper here [pdf]. The research specifically suggests that near surface water ice in the dry equatorial regions of Mars could have been there much more recently that previously believed. It also suggests, by the rarity of this discovery, that there is likely almost no near surface ice in the equatorial regions, at present.

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