Land of Martian slope streaks

Land of Martian slope streaks
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on May 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a typical example of the many slope streaks found in the rough and very broken region north of the Martian volcano Olympus Mons, the largest in the solar system.

See this May 2019 post for a detailed explanation of slope streaks. While they appear to be avalanches, they do not change the topography of the ground, sometimes flow over rises, and appear to be a phenomenon entirely unique to Mars. While no theory as yet explains them fully, the two most favored postulate that they are either dust avalanches or the percolation of a brine of chloride and/or perchlorate in a thin layer several inches thick close to the surface. In both cases the streak is mostly only a stain on the surface that fades with time.

The location of this cool image however tells us something more about them.
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Inactive volcano vent on Mars

Inactive volcanic vent on Mars
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Overview map

Cool image time! The photo to the right, cropped, reduced and annotated to post here, was taken on July 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The left image shows a pit that the scientists label a “vent” near the giant volcano Pavonis Mons. The right image is identical, except that I have brightened it considerably to bring out the details in the shadowed area.

As you can see, this pit is filled, and does not appear to have any existing openings into more extensive underground passages.

The white dot on the overview map on the right shows this vent’s location, to the south of Pavonis Mons, and in line with the giant crack that splits three of Mars’ four largest volcanoes. The vent is even aligned the same as that crack, from the northeast to the southwest. The black dots mark the locations of the many cave pits found in this region.

Was this a volcanic vent? If you look at the full image you will see that this pit aligns with a shallower pit to the southwest, with a depression linking the two. Visually this suggests this is a faultline which in turn makes for a good outlet point for lava flow.

Though the data suggests this is a volcanic vent, that supposition is as yet unproven. The full image does not show much evidence of a flow from the pit, which suggests instead that we are merely looking at a spot where the ground cracked along fault lines.

A Mars mesa carved by floods and lava?

Overview map of Kasei Valles

With today’s cool image we once again start our journey from afar, and zoom in. The overview map to the right focuses in on the thousand-mile-long Kasei Valley on Mars.

The blue area is where scientists postulate a lake once existed, held there by an ice dam (indicated by the white line). At some point that ice dam burst, releasing the water in a catastrophic flood that created the braided flow features that continue down Kasei Valles to the northern lowland plain of Chryse Planitia.

The black area marks a giant lava flow that scientists believe came later, following the already carved stream channels for a distance of 1,000 miles, traveling at speeds of 10 to 45 miles per hour.

The red dot near the Kasei Valles resurgence is today’s cool image.
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Perseverance as seen from orbit

Perseverance as seen from orbit
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Overview map
Click for interactive map.

The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) have snapped a picture of Perseverance at its present location in Jezero Crater.

The first image to the right, cropped to post here, shows the rover as a white dot to the right of the two long sand dunes. If you look close image, you can see the rover’s tracks near the bottom of the image.

Ingenuity is likely also in the full image, but is likely too small for MRO’s high resolution camera to pick out.

The second image is a overview map. The green dot marks the rover’s position, with the red dot Ingenuity’s present position. The dotted white line shows the route the rover has taken so far. The light brown line indicates the flight paths for all of Ingenuity’s flights. The yellow dotted line indicates the future planned route of Perseverance.

With Mars about to slip behind the Sun, communications with both rovers, Perseverance and Curiosity, as well as all the orbiters, will shortly go silent for about two weeks.

When that pause ends, the question will be where Perseverance goes next. The original plan was to retreat back along its previous path, going to the southeast before heading north past the landing site. I strongly suspect that they will instead head directly to the landing site, going to the northeast across the rough terrain, both to see something new as well as further test the rover’s ability to travel tougher ground.

They avoided that area initially because they were still in the rover’s check out period. Now that they know it works, there is no reason to avoid that ground, especially because it will be ground they have not viewed before. They could even use Ingenuity to scout it out more thoroughly.

Rivulets in Martian lava

Overview map

Today’s cool image is another example of scientists finding cool things hidden within distant pictures. The small white rectangle on the overview map to the right shows us where we are heading, to the severely eroded lava plains to the southwest of Mars’ largest volcano, Olympus Mons.

The white spot is about 500 miles from the caldera of Olympus Mons. In elevation it sits about 58,000 feet below that caldera, more than twice the height of Mt. Everest. Yet, despite these great distances, the material at that white rectangle was almost certainly laid down during an eruption from Olympus Mons, thus illustrating the gigantic scale of volcanic events on Mars. Because of the red planet’s light gravity, about 38% of Earth’s, not only can lava flow farther, it does so much faster.

The second image below is a wide angle photo taken by the context camera on Mars Reconnaissance Orbiter (MRO) in January, 2012, rotated, cropped, expanded, and enhanced to post here.
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Glaciers in the Martian south latitudes

Glaciers in Mars' southern hemisphere
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Most of the glacier cool images I have posted in the past few years from the high resolution camera on Mars Reconnaissance Orbiter (MRO) have shown the obvious glacial features found in the northern hemisphere in that 2,000 mile long strip of chaos terrain at about 40 degrees latitude I dub “Glacier Country.”

Today’s glacier image to the right, cropped and reduced to post here, takes us instead to the southern hemisphere, into Hellas Basin, the death valley of Mars. The picture was taken on April 8, 2021, and in the full picture gives us a myriad of examples of glacial features. The section featured to the right focuses in on what appears to be an ice covered south facing slope, which in the southern hemisphere will get the least sunlight.

Think of the last bits of snow that refuse to melt after a big blizzard. They are always found in shadowed areas, which in the southern hemisphere would be this south-facing slope.

The overview map below shows how this location, marked by the small white rectangle, is inside Hellas Basin, at a low altitude comparable to the northern lowland plains. The feature is also a comparable latitude, 43 degrees south, to the glacier country of the north.
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A clue to the Martian history of volcanic eruptions

Dark layers in Medusae Fossae Formation
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Anyone who has taken even a single glance at a map of Mars cannot help but recognize that the red planet was once engulfed with repeated gigantic volcanic eruptions able to build numerous volcanoes larger than anything seen anywhere else in the solar system.

The cool image to the right, rotated, cropped, and enlarged to post here, provides a clue into those past eruptions, now thought to have been active for more than several billion years, with the most recent large activity ending several tens of millions of years ago. The photo was taken on May 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows just one tiny portion of the vast Medusae Fossae Formation, the largest thick volcanic ash deposit on Mars, about the size of India and what scientists think is the source of most of the planet’s dust.

What makes this picture interesting are the dark layers in the lower hollows. They indicate that this deposit was placed down in multiple eruptions, some of which produced material that appears dark blue in MRO images, and suggest that eruption was different than previous and subsequent eruptions.

The white cross on the overview map below notes the location of this picture in the Medusae Fossae Formation.
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How to discover interesting things on Mars

Overview map

Today’s cool image will do something a little different. We are going to begin in orbit, and by step-by-step zooming in we will hopefully illustrate the great challenge of finding cool geological features on the surface of Mars.

The first image to the right is an overview map of the Valles Marineris region. To its east, centered at the white dot, is a vast region of chaos terrain, endless small buttes and mesas and criss-crossing canyons. Travel in this region will always be difficult, and will likely always require some form of helicopter to get from point to point.

What is hidden in that terrain? Well, to find out you need to take a global survey from orbit with a good enough resolution to reveal some details. Below is a mosaic made from two wide angle context camera pictures taken by Mars Reconnaissance Orbiter (MRO).

Context mosaic of chaos terrain
For full images go here and here.

This mosaic, rotated, cropped, and reduced to post here, only captures a small section of the long north-south strips taken by MRO. The orbiter has taken tens of thousands of these strips, in its effort to produce a global map of Mars that shows some reasonable detail.

Do you see anything in this mosaic that looks interesting? Scientists need to pore over such images, one by one, searching for geology that is both puzzling and revealing. Sometimes the features are obvious, such as a single blobby crater in the flat relatively featureless northern lowlands.

Sometimes however the search can be slow and time-consuming because the terrain is complex, as is the example to the right. The many mesas and canyons can hide many interesting features. Since MRO can’t possibly take high resolution photos of everything, scientists have to pick and choose.

The planetary scientists who use MRO did find something here worth looking at in high resolution. Can you find it? Normally I’d provide a box to indicate it, but this time I’d thought I’d challenge my readers. Before you click below to see the feature, see if you can find it yourself in this mosaic. What would you want to photograph in high resolution?
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Glacial falls on Mars

A glacial falls on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on July 2, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It provides us just one more clear example of the many glaciers found in that 2,000-mile-long strip of chaos terrain at 30 to 47 degrees north latitude that runs between the northern lowland plains and the southern cratered highlands, a region I like to call Mars’ glacier country.

What makes this glacial feature interesting is that these ice-filled alcoves are south-facing, which in the northern hemisphere means they get the most sunlight. Yet, the ice here remains, well-protected by its layer of dust and debris. Think of the dirty ice slush that manages to survive the longest on city streets in the spring. The dirt acts as protection so that the ice takes more time to melt.

The overview map as always provides our context.
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Badlands on the floor of a Martian crater

Badlands on the floor of a Martian crater
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, shows one small section of a 30-mile-wide unnamed crater in the cratered equatorial regions of Mars northeast of Hellas Basin. Taken on July 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the science team labeled merely as “Rocky crater fill.”

Being at 17 degrees south latitude, there shouldn’t be any ice features in this crater, and the high resolution image to the right seems to confirm this. All we see is an endless plain made up of innumerable small sharp rock ridges interspersed with small low areas filled with sand dunes. This is bed rock, and if its strange stucco-like appearance was caused by a past glacial era, that era is long gone.

Below is a mosaic showing the entire crater, created from two MRO context camera images.
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Lozenge-shaped hole in Martian crater

Hole in crater floor
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Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The left image shows what the scientists have dubbed a “lozenge-shaped depression” in the middle of an unnamed 60-mile-wide crater in the southern cratered highlands of Mars. The right image shows the same exact depression, but I have brightened the photo in order to see the details in the shadowed depression.

Though the image is inconclusive, the bottom of the darkest spot in that depression cannot be seen, suggesting it could be an entrance into a larger void below.

Even if there is no voids below, why is this depression here? What caused it? The wider view of MRO’s context camera below might give us a hint.
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An example why scientists think there were catastrophic floods on Mars

Broken mesas on Mars
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Today’s cool image provides a nice illustration why scientists have long assumed that in the distance past there had been catastrophic floods of liquid water on Mars. The photo to the right, rotated, cropped, and reduced to post here, was taken on July 6, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an east-west gully cutting between mesas to the north and south.

Because the highest mesas seem to be aligned, this suggests they were once part of the same formation, and something came along to carve that gap and gully between them.

What made the break? The overview map below as usual provides some context, which also provides a possible explanation.
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Data from Opportunity suggests surface dew periodically appears even in the dry equatorial regions

Using data from the rover Opportunity, scientists now think that the renewal of Martian salt crusts on rock surfaces on the rim of Endeavour Crater could possibly by caused by the appearance of rare thin wetting events, and that such events could have even occurred very recently and be on-going..

The scientists looked at the rate of erosion and renewal of the salt crusts, and found them to be in a steady state. The erosion is slow, taking from 200,000 to 2,000,000 years to remove 1 to 2 millimeters. However, periodically a thin film of water or wetting occurs, not unlike dew on Earth, which quickly acts to renew the crust. As David Mittlefehldt of the Astromaterials Research Office at the Johnson Space Center and the lead author of the paper explained to me,

Taken together, the data leaves open the possibility the salt mobilization has occurred within the last few thousand years. It could be ongoing in the sense that over a period of thousands? or hundreds? of years it might happen again.

In other words, the evidence suggests that every few hundred or thousand years the surface of these rocks gets wet, which results in the placement of a new thin layer of salt crusts.

Mittlefehldt also emphasized to me that these wetting events are rare, and “there is also the case that such an event may never come again because of changing conditions.”

The situation is essentially like on Earth, where in some places hydrologists measure the size of floods by how rare they are. A 1,000 year flood is big, but it happens very rarely. At Endeavour Crater these wetting events are comparably rare, but they do not involve big floods, but a mere moistening of the ground.

The location of Endeavour Crater is about 2 degrees south latitude, so it sits in the dry equatorial regions where no surface or near surface ice has so far been found. However, the cyclic nature of Mars’ orbit and obliquity could have changed this in the past, and could change this again in the future. At this time we simply don’t have enough information to know.

On the edge of Mars’ glacier country

Color dry mesas on Mars
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Today’s cool image sits right on the southern edge of Mars’ northern glacier country, at 29 degrees north latitude. The picture to the right, cropped and reduced to post here, was taken of this location on June 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be the exposed and scraped bedrock and mesas on the floor of an unnamed 60-mile-wide crater.

That scraped bedrock is quite beautiful, reminiscent of the bare carved mesas and bedrock one sees throughout the southwest of the United States. To hike from that central valley to the top of the bright mesa would be a fine experience, especially because of the suggested change in colors in the color strip.

The overview map below gives more context.
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Glaciers and mesas on Mars

Overview map

Cool image time! Today we return to glacier country on Mars, that band of mensae mesas and glaciers that stretches more than 2,000 miles in the northern mid-latitudes, as shown on the overview map above.

No rovers or landers have yet visited this region, nor are any planned. To the west just beyond the map’s left edge is the planned landing site of Europe’s Franklin rover. To the east and south and just beyond the map’s right edge is where America’s Perseverance rover presently travels in Jezero Crater.

Our journey today begins from afar, and will steadily zoom into the area of the red cross and a most intriguing feature seen in a recent picture taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Before we look at that high resolution image, it is better to view the area using MRO’s context camera, as what it shows helps make sense of the features in the close-up.
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Perseverance’s 2nd drill attempt to get sample appears successful

It appears that Perseverance’s second drill attempt on Mars has successfully obtained sample material in its core.

Data received late Sept. 1 from NASA’s Perseverance rover indicate the team has achieved its goal of successfully coring a Mars rock. The initial images downlinked after the historic event show an intact sample present in the tube after coring. However, additional images taken after the arm completed sample acquisition were inconclusive due to poor sunlight conditions. Another round of images with better lighting will be taken before the sample processing continues.

Once they know for sure if they have a sample, they will store it and then move on, heading to the area that Ingenuity scouted for them in mid-August.

Posted halfway to Las Vegas.

A peanut-shaped crater in the northern plains of Mars

Context camera image of peanut-shaped crater
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Cool image time! The photo to the right, rotated, cropped and reduced to post here, was taken in May 2008 by the wide angle context camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have since labeled a “peanut-shaped crater.”

What caused this unusual shape? The obvious and most likely explanation is that this was a double impact that occurred simultaneously. Imagine the ground being hit either by an asteroid with two lobes or by two similar-sized asteroids falling side-by-side.

Fast forward thirteen years to 2021. In the fifteen years since 2006 when MRO begin science operations in orbit around Mars no high resolution images were taken of this crater. Finally, on July 30, 2021, scientists finally decided to take a high resolution image of this crater’s western half. You can see that image below, rotated, cropped, and reduced to post here.
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Stucco on Mars!

Stucco on Mars
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Cool image time! The picture to the right, cropped to post here, was taken on June 8, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a strangely flat plain with a complex stucco-type surface of ridges and depressions. The sunlight is coming from the west, which makes the smoother flat areas depressions.

What are we looking at? What causes this strange surface? Make sure you look at the full image, because the section I cropped out doesn’t give a true sense of the terrain’s vastness.

The MRO science team labeled the photo “volcanic terrain,” but that tells only part of the story, since this volcanic terrain is actually part of Mars’ most interesting lava plains, as the overview map below shows.
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An ancient curving channel on Mars

Context image of curving channels
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the wide angle context camera on Mars Reconnaissance Orbiter (MRO) in April 2019. It shows an area on Mars where a number of meandering curving channels flow downhill from the west to the east.

Earlier MRO images had already spotted these channels, so when this context image was taken the scientists also took a high resolution image of the same channels, with the white box indicating the area covered by the rotated, cropped, and reduced image below.

Both images are today’s MRO image of the day, where the MRO team notes that “The objective of this observation is to examine a complex network of channels. Some parts of the channels are quite curved.”
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New cracks across old Martian lava flows

New cracks across an old lava flow
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It captures one of the many deep straight fissure canyons that make up the feature dubbed Cerberus Fossae in the center of Mars’ volcano country.

The crack is called a graben, and happens when the ground is either stretched from pressure from below, or when two adjacent large blocks of material move sideways relative to each other.

What makes this particular graben interesting are two features. First, the overlapping break suggests something complex took place at this spot when the crack separated. Second, the crack cut across the foot of an older frozen lava flow, meaning it has to be younger than that flow.

The overview map below provides a clue when that lava flow might have occurred, while also suggesting this crack in Cerberus Fossae might be much younger than expected.
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A weak avalanche season on Mars?

The north pole scarp
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Today’s cool image from Mars is cool both for what is visible in the photo and for what is not, the latter of which might turn out to be a discovery of importance.

The photo to the right, cropped and reduced to post here, was taken on June 24, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a section of the edge of Mars’ north polar ice cap, with north at the top.

This scarp is probably more than 2,000 feet high, though that height drops to the south as the upper layers disappear one by one from either long term erosion or sublimation. Those layers represent the visible information in the photo that is cool. They give us tantalizing clues about the geological and climatic history of Mars. Each layer probably represents a climate period when the north icecap was growing because the tilt of the planet’s rotation was even less than the 25 degrees it is now. When that tilt is small, as small as 11 degrees, the poles of Mars are very cold, and water ice migrates from the mid-latitudes to the poles, adding thickness to the icecaps. When the tilt grows, to as much as 55 degrees, the mid-latitudes are colder than the poles, and the water ice migrates back to the mid-latitudes.

What is not visible in this picture, however, might be far more significant.
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A dry bedrock Martian crater floor?

A dry bedrock crater floor?
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is a very eroded crater at about 26 degrees north latitude. The image shows the crater’s crater floor, with a variety of bedrock-type features, sharp ridges, abrupt scarps, and flat smooth plateaus, with a hint of lobate glacial flows in the image’s southeast quadrant.

At 26 north latitude, it is unlikely that anything here is icy, unless it is very well protected by debris. Most of these features are almost certainly bedrock, though their formation could very well have been shaped by ice in past eons when this location was more amenable to water ice.

The wider MRO context camera image of the entire crater, plus the overview map, give a larger picture, and raise some interesting questions.
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Lacy patterns in the high north of Mars

lacy patterns in the high north of Mars

Cool image time! The photo to the right, cropped, reduced, and rotated so that north is up, was taken on May 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the strange lacy patterns seen routinely in the very high northern latitudes surrounding the Martian north pole.

Located in a region of the vast northern lowland plains dubbed Scandia Tholi, such features are apparently common here. From a 2011 geology paper of the region’s geological history:

We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters.

The small circular feature near the bottom of the picture appears to be a mesa, and might be a pedestal crater, so old that the surrounding terrain has worn away and left the hardened-by-impact crater as a butte. To its right is a larger circular mesa with its scarp well eroded into hollows. This might also be a pedestal crater, or not.

The white lacy patterns could be frost, either water ice or dry ice. That the white lace tends to favor the north-facing slopes lends support to this guess. The photo was taken in the early spring, so the thin mantle of carbon dioxide that falls to cover the polar region south to sixty degrees latitude is only beginning to sublimate away.

A Martian river of ice

Glacial flow 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 13, 2021 by the high resolution camea on Mars Reconnaissance Orbiter (MRO). It spans the entire 4.7 mile width of the southern hemisphere canyon dubbed Reull Vallis. The white arrow indicates the direction of the downhill grade

The scientists title this image “Lineated Valley Fill.” The vagueness of this title is because they have not yet confirmed that this lineated valley fill is a glacier flowing downhill to the west.

Nonetheless, the material filling this valley has all the features one expects glaciers to exhibit. Not only is the the lineation aligned with the flow, it varies across the width of the canyon as glaciers normally do. At the edge the parallel grooves are depressed, probably because they are torn apart by the canyon walls as the glacier flows past. In turn, at the center of the flow the grooves are thinner and more tightly packed, and appear less disturbed. Here, the flow is smooth, less bothered by surrounding features.

This pattern also suggests the merging of two flows somewhere upstream.

A glance at the spectacular Concordia glacier in the Himalayas near the world’s second highest mountain, K2, illustrates the similarity of this Martian feature to Earth glaciers.

Reull Vallis itself flows down to Hellas Basin, the deepest basin on Mars. As it meanders downhill along its 650 mile length it steadily gets wider and less distinct as it drops into Hellas. Along its entire length MRO has photographed numerous similar examples of this lineated fill, all suggesting that under a thin layer of debris is a thick glacier, slowerly carving this canyon out.

The overview map below illustrates these facts nicely, while further reinforcing these glacial conclusions.
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A chain of Martian sinkholes

Chain of sinkholes on Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on June 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a somewhat straight depression with several wider and deeper pits along it.

The feature immediately suggests sinkholes that exist because the ground is sagging into voids below ground. Yet, both the straight and circular depressions also appear filled, showing no evidence that they connect to any below ground cavities.

Are the sinks the result of a fissure produced by a graben, when two large blocks shift relative to each other to cause a fissure to appear? Or are they evidence of an underground lava tube? Or maybe they are the filled remains of a now mostly buried canyon carved by water or ice?

As always, a wider view helps clarify things, though whether it answers the question is uncertain.
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Glacial ice sheets on Mars?

Glacial ice sheets on Mars?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on June 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is in Mars’ glacier country, that strip of chaos terrain that runs about 2,000 miles along the transition zone between the northern lowland plains and the southern cratered highlands at 30 to 47 degrees north latitude. This particular feature is located in Deuteronilus Mensae, the westernmost region of that strip of chaos.

I call this glacier country because practically every image taken by MRO’s high resolution camera in this region suggests the presence of glacial material covered by a protective layer of debris. The photo to the right is typical, though a bit more puzzling because of the depressions that appear to run along highpoints.

As usual, the overview map below helps explain what we are looking at.
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Peeling thin layers on a Martian plateau

Peeling thin layers on Mars
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Cool image time! The photo to the right, cropped to post here, was taken on May 14, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels as “light-toned layered deposits.”

Their focus, rightly from a geologist’s perspective, is the contrast in color between different layers, suggesting different composition and thus a different formation history for each layer.

To me, what made this feature appealing is the thinness and number of its layers. It reminded me of fillo pastry, “unleavened flour dough formed into very thin sheets or leaves.”

If you look at the full image you will see that cropped section only covers one edge of a tongue-shaped plateau, with similar layers revealed along its entire cliff wall. It is almost like those layers have been peeling off for eons to leave the plateau behind.

The location below gives some context.
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White blobs on Mars

White blobs on Mars
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Time for another “What the heck?” image. The photo to the right, cropped to post here, was taken on May 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be a series of white circular features aligned with a ridge line.

Are these eroded craters? Maybe, but their alignment with those ridges suggests otherwise. If you look at the full image, you will see further parallel ridges to the north and south, also with similar circular blobs lined along them. Furthermore, the flat surrounding terrain, part of the northern lowland plains north of the resurgences from Valles Marineris, has a scattering of very normal looking craters, with distinct rims and even some glacial material within. As this is at 44 degrees north latitude, the presence of glacial material inside craters is not surprising.

Thus, the white blobs are likely not craters, but some form of eruptive material from below, coming up along those ridges which are probably faultlines. The whiteness suggests that material is water ice, but this of course is unconfirmed.

The question is of course, why? What would cause water ice to erupt along these faultlines? And why are such features not seen elsewhere? Faults and underground ice are common on Mars. Yet, I don’t remember seeing features such as this in any other Martian images.

Martian lava flooded crater?

lava flooded crater?
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A quick cool image! The photo to the right, rotated, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) more than a decade ago, on June 1, 2010. I post it now because it is today’s MRO picture of the day, and is definitely cool. The caption:

One of a few “scaly-looking” inselbergs within regional platy-ridged flows in Elysium Planitia. This inselberg has a broken and blocky appearance with some of the blocks being tilted. Could this be the remnant of a once extensive mantling deposit? An inselberg is an isolated hill or mountain rising abruptly from a plain.

The wider image by MRO’s context camera below, also rotated, cropped and reduced to post here, illustrates even more forcefully how isolated this circular set of blocks is.
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The sublimating surface of Mars’ northern plains?

Sublimating patches on Mars?
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Cool image time! The photograph to the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter on May 27, 2021. A sample image, likely taken not as part of any specific scientist’s research but by the camera team in order to maintain the camera’s temperature, shows an area of the Martian northern plains that appears filled with rough scattered depressions, possibly caused by sublimation of buried ice.

The location, at 54 degrees north latitude, is far enough north to easily have a lot of buried ice. It is also only about 40 miles to the east of Milankovič Crater, where scientists have found many scarps that appear to have exposed layers of ice in their cliff faces.

However, the location has other components that must raise questions about this sublimating ice hypothesis.
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