Tag: MRO

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Today’s cool image is mostly an example of the present unknowns of Mars. The picture to the right, cropped, reduced, and sharpened to post here, was taken on April 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team quite rightly labels this vaguely as “bright materials,” referring to the bright rim of that crater as well as the scattered bright patches on the surrounding plain. This vagueness tells us that the scientists don’t have enough data yet to definitively identify this stuff, though they know it is distinctly unique because of its inexplicable bright albedo compared to everything around it.

That the crater rim (as well as all the crater rims in the full picture) exhibit this same brightness suggests this material was excavated from below when the impacts hit. The surrounding patches suggest that erosion has exposed this buried material at these points.
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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on April 3, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

I have enhanced the image to make it easier to see the details. It appears we are looking at three layers. At the base (on the left side of the picture) is a relatively smooth bottom layer with the highest number of scattered craters. On the top (on the right side of the picture) is a somewhat rough layer with fewer craters.

In between is a middle layer that appears to be seeping out from under the top layer.

The science team seems to agree with my last guess, as they label this image “Possible basal seepage at flow boundary.” The flow boundary is the edge of a lava flood that scientists believe covered a distance of about 1,400 miles at speeds ranging from 10 to 45 miles per hour.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled it “Looking for Gullies” because the researchers were likely searching for such geological features on the cliff wall that runs down the right side of the picture.

What is more significant however about this picture is the glacier features in the canyon below that cliff. The downhill grade is to the southwest, and it is very evident that the canyon is filled with glacial-type debris, flowing down that grade. Along the base of the cliff the flow seems focused but squeezed, the larger blocks to the west moving slower and thus acting like a wall themselves. In between the flow moves like rapids in a narrow part of a river, albeit in slow motion.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 28, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this picture “enigmatic terrain.” And there are certainly mysteries here. For example, why are there scattered tiny knobs across the surface in the low areas, but not on the higher areas? Also, what caused that top layer to get stripped in places? Was it erosion from wind? Or did some other process cause that layer to vanish in these spots?

Note too that this landscape has few craters. Whatever happened here occurred recently enough that it was able to cover over the impact history from the early solar system that peppered the planets with craters as the planets formed. Though impacts continue even to this day, the impact rate is far less, which allows younger terrain like this to remain largely crater free.

The location provides us some answers, but it still leaves much of this geology a puzzlement.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists describe these features as “dendritic relief features,” an apt description of the thousands of miles of river-like meandering ridges that orbital images have discovered in the past decade scattered across Mars, as noted in 2016:

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low – in most other environments, the channels are worn away before they can become inverted.

The most dramatic example of these Martian ridge rivers are the fernlike ridges in Antoniadi Crater. The ridges to the right however are almost as striking.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 27, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

That the science team labels this “Monitoring Slopes for Changes on Eastern Terraces of Mojave Crater” is quite understandable. The number of apparent dentritic channels suggests strongly the possibility of change over time, which is why MRO has been used repeatedly to monitor this location, beginning in 2006, when the science team noted this in a caption:

Aptly-named Mojave Crater in the Xanthe Terra region has alluvial fans that look remarkably similar to landforms in the Mojave Desert of southeastern California and portions of Nevada and Arizona.

Alluvial fans are fan-shaped deposits of water-transported material (alluvium). They typically form at the base of hills or mountains where there is a marked break, or flattening of slope. They typically deposit big rocks near their mouths (close to the mountains) and smaller rocks at greater distances. Alluvial fans form as a result of heavy desert downpours, typically thundershowers. Because deserts are poorly vegetated, heavy and short-lived downpours create a great deal of erosion and nearby deposition.

There are fans inside and around the outsides of Mojave crater on Mars that perfectly match the morphology of alluvial fans on Earth, with the exception of a few small impact craters dotting this Martian landscape.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this “Monitoring Irregular Terrains in Western Arabia Terra.” I label it more bluntly as another one of MRO’s “What the heck?!” images. For all I know, this is nothing more than a discarded Vincent Van Gogh painting, thrown out because even he couldn’t figure out what he was painting.

The best guess I can make, just from the picture alone, is that some of the dark spots are vents from which the white stuff vented at some point, either as small lava or mud volcanoes. As the location is close to the equator, near surface ice is almost certainly not a factor in what we see.

In any case there is no way to reasonably decipher this picture, just by looking at the picture. It is necessary to take a wider view.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 27, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the terraced layers descending down a 7,000-foot-high ridgeline within Hebes Chasma, one of several enclosed chasms that are found to the north of Mars’s largest canyon system, Valles Marineris.

The white dot on the overview map above marks this location, inside Hebes. The rectangle in the inset indicates the area covered by the picture, which only covers the lower 5,000 feet of this ridge’s southern flank.

The ridgeline might be 7,000 feet high and sixteen miles long, but it is dwarfed by the scale of the chasm within which it sits. From the rim to the floor of Hebes is a 23,000 foot drop, comparable to the general heights of the Himalaya Mountains. Furthermore, this ridge is not the highest peak within Hebes. To the west is the much larger mesa dubbed Hebes Mensa, 11,000 feet high and 55 miles long.

The terraces indicate the cyclical and complex geological history of Mars. Each probably represents a major volcanic eruption, laying down a new bed of flood lava. With time, something caused Hebes Chasm to get excavated, exposing this ridge and these layers.

The excavation process itself remains unclear. Some scientists think the entire Valles Marineris canyon was created by catastrophic floods of liquid water. Others posit the possibility of underground ice aquifers that sublimated away, causing the surface to sink, eroded further by wind. Neither theory is proven, though the former is generally favored by scientists.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 24, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample,” it was likely taken not as part of any specific research request but to fill a gap in the schedule in order to maintain the camera’s proper temperature.

In this case the camera team got something quite intriguing. The entire terrain is reminiscent of stucco found on the outside walls of southwest homes. What makes even more intriguing is that the stucco appears to be material that has covered the terrain, based on the two craters that appear half-buried by it. Moreover, this picture only captures a small portion of this landscape, which extends like this over an area approximately 40 miles squared.

What caused this strange terrain? As always, the overview map below provides a clue, though no firm answers.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 27, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample,” it was likely taken not as part of any specific research project but to fill a gap in the schedule in order to maintain the camera’s proper temperature.

Whenever the camera team needs to do this, they try to find an interesting object to photograph, and often succeed. In this case they focused on the geology to the right. I suspect that at first glance my readers will have trouble deciphering what they are looking at. Let me elucidate: This this a 2.5-mile-wide canyon, about 1,000 feet deep, that is bisected by a ridge about 500 feet high.

On the sunlight walls of this canyon you can see boulders and debris, with material gathered on the canyon floor. The smoothness of the floor suggests also that a lot of Martian dust, likely volcanic ash, has become trapped there over the eons.
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Cool image time! The picture to the right cropped, reduced, and sharpened to post here, was taken on January 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also rotated it so north is up. Labeled simply as a “terrain sample,” it was likely taken not as part of any specific research request but to fill a gap in the schedule in order to maintain the camera’s proper temperature.

In this case the timing allowed the camera team to capture this breath-taking picture of these graceful arching dunes sitting in what is likely the near-surface ice sheet that covers much of the red planet’s high latitudes. That sheet is not pure ice, but a complex mixture of ice, dirt, dust, and sand, covered during the winter by a thin mantle of dry ice.

The isolated dunes appear to be ridges sticking up from that flat terrain, but this impression is probably incorrect, based on the location.
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Cool picture time! The photo to the right, cropped, reduced, and sharpened to post here, was taken on September 30, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample,” it was most likely taken not as part of any specific research project but to fill a gap in the schedule in order to maintain the camera’s temperature.

The image is fascinating nonetheless, as the landscape is typically alien for Mars. What caused the many random ridges and knobs? Why are there oblong areas that are smooth and have no ridges? And why is there dark material inside that crater that appears to have been blown out to the northeast? If you click on the image to see the full image, not all the craters look this way. One has a similar dark feature, but others are as bland as the entire terrain.

The overview map below only increases these mysteries, even if it does provide some further data.
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Cool image time! The picture above, rotated, reduced, and sharpened to post here, was taken on September 2, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The tiny white dot near the lower center of the overview map below marks the location, on the northern wall of the smaller parallel canyon to the much larger part of Valles Marineris dubbed Coprates Canyon.

The scientists label this a “slope deposit.” What I see is a dust glacier flowing down hill in that long hollow (indicated by the arrows), with the ripple dunes actually acting almost like waves. Nor is this description unreasonable. On Mars the dust will gather in the hollows of these slopes and over time, with no rain and little wind to disturb them, will begin to flow down much like a glacier.

In this case, the descent is gigantic, considering the size of Valles Marineris. From the top to bottom of this image the elevation drop is about 14,000 feet over a distance of 11 miles.

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Cool image time! The picture above, reduced and rotated to place north to the left, was taken on November 5, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labeled it “Stepped Features in Tartarus Skopulus”. The white dot on the overview map to the right marks the location, right at the equator on the northern edge of the Medusae Fossae Formation, the largest volcanic ash field on Mars, about the size of the subcontinent of India. As I wrote in a post in 2024:

It is believed that most of the planet’s dust comes from this ash field. It is also evident that the ash is a leftover from the time period more than a billion years ago when the giant volcanoes that surround this field were erupting regularly. The eruptions laid down vast flood lava plains that coat the surface for thousands of miles.

The ash either came from the eruptions themselves, or was created as the thin Martian wind eroded those flood lava plains, slowly stripping ash from the top. The ash then gathered within the black-outlined regions on the map.

In that 2024 post the cool image showed another location on the north edge of Medusae. In that case the prevailing wind had carved long parallel ridges as it pulled ash from the field.

Here, the wind appears to play no part, or if it did, it produced a very different terrain. At first glance it appears the stepped terraces formed as the ash field began to slide downhill to the north, spreading to crack along the curved lines. The inset especially suggests this explanation.

A closer look instead suggests these terraces each represent a different layer of ash placed down by a sequence of eruptions. Over time the prevailing winds, which here appear to generally blow to the south, stripped off the top of each layer, creating this stair-step landscape.

I however have no guess as to why the terraces are curved. Regardless, it is all strange, but quite beautiful in its own way.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 25, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this a “layered feature,” which is appropriately vague in order to not prematurely push a conclusion that is not yet proven. Extensive orbital imagery and data however strongly suggests the layers inside this crater are glacial in nature, each layer laid down during Mars’ many thousands of climate cycles as the planet’s rotational tilt swung back and forth from 11 degrees to 60 degrees. According to the most popular theory today, when that tilt was high, the mid-latitudes (where this 3,000-foot-wide unnamed crater is located) were actually colder than the planet’s poles. The water ice at the icecaps would then migrate from the poles to the mid-latitudes, causing the glaciers to grow.

When the tilt was low the process would reverse, with the mid-latitudes now warmer than the poles, causing the glaciers to shrink. The wedding cake nature of these layers is likely because, over time, Mars has steadily lost its total budget of water to space, so with each cycle the glacier could not grow as much.

Though many such glacial-filled craters have been found in the mid-latitudes, reinforcing these theories, the location of this crater is even more interesting.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 31, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “Impact Ejecta with Marginal Pits,” though even on the full image I am not sure what the impact ejecta is. The pits themselves appear to have formed when near-surface ice sublimated away during the summer months. The location is at 59 degrees north latitude, deep within the Martian northern lowland plains. Since orbital data suggests much of those plains at this latitude has an ice table of some thickness near the surface, it is very reasonable to assume these pits formed when summer sunlight heated that ice, turning it to gas which eventually pushed out to form the pits.

But what about the impact ejecta? Where is it? And where is the crater from that impact?
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Glacier country in the northern mid-latitudes of Mars

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on November 4, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels the features in the lowland below the mesas “ribbed terrain.” To me it looks like peeling paint. What it is however is glacial material, a lot of it. The white dot on the overview map above marks the location, in the middle of the 2,000-mile-long mid-latitude strip in the northern hemisphere I label glacier country, because practically every high resolution image of this region shows glacial features like those on the right.

The mesa with the crater on top gives a clue on the geological history. This is chaos terrain, a region of random mesas cross-crossed with canyons and wide low plains, as shown in the inset. The entire surface was probably once at the same height as the top of that mesa with the crater. Over time glacial ice eroded away along fault lines. As that sublimation process continued, the fault lines widened to became canyons, then the flat plains, with the isolated mesas remaining between.

The “peeling paint” terrain is likely a layer of ice that is in the process of sublimating away.

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Cool image time! The picture to the right, cropped to post here, was taken on September 26, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

I picked this image out of the MRO archive because of the many dust devil tracts that cut across the entire image, traveling in all directions with no apparent pattern. I also picked it because those tracks also cut across the many parallel small ridges that appear to be ancient ripple dunes that have since hardened into rock. What makes this landscape puzzling is how those dust devil tracks leave no evidence on those ridges. It is as if the ancient ripple dunes were laid down after the very recent dust devil tracks, even though that is chronologically entirely backwards.

Apparently, the dust devil tracks form because the devil only disturbs the dust that coats the flat low ground between the ridges. The ridges themselves are hard, and thus the devils, produced in Mars’ extremely thin atmosphere, can leave no mark.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 8, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture’s research focus is the gullies, which the scientists’ describe as “perched pole-facing gullies on ancient crater wall.” Perched means the start and end of each gully is on that crater wall, linked neither to the top or bottom of the wall itself. That the gully starts below the top means whatever caused it came from within the wall itself, not from the plateau above. That it ends before the crater floor means the process that cut the gully out was not powerful enough to reach the bottom.

That the gullies are on the interior north wall of this unnamed 25-mile-wide crater means they get less sunlight year round, something that must play a part in causing the gullies.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 4, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is labeled as a “terrain sample,” so it likely was taken not as part of any specific research project but to fill a gap in the schedule in order to maintain the camera’s proper temperature.

The picture shows a flat rippled plain with a handful of very small thin ridges, oriented 90 degrees from the smaller ripples and sticking up a few feet above them.

The rough surface of the small ripples suggest these are dunes of sand that have hardened into rock. The thin larger ridges suggest an underlying topography buried by the sand. The dunes however might not be dunes at all, as indicated by their location.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 1, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label “a fracture with clays.”

This canyon is about a mile and a half wide, with the floor ranging from 800 to 1,100 feet to the rim. It was not formed initially by any ice or water flow, but by a spreading of the crust, forcing cracks to form that might have later been modified by wind, ice, or water. The presence of clays in this canyon strengthens that later ice/water modification, as clays require water to form.

The streaks on the northern wall are slope streaks, an unexplained phenomenon unique to Mars. While at first glance they look like avalanches, they have no debris piles at their base, and do nothing to change the topography. In fact, streaks can sometimes go uphill for short distances, following the surface. They happen randomly throughout the year, and fade with time.

It is believed their cause is related to dust avalanches, but this is only one of a number of theories that attempt to explain them. None is entirely satisfactory.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 25, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule so as to maintain the camera’s proper temperature.

The terrain is definitely blobby, with some hollows appears to have ripple dunes suggesting dust and sand. The rounded mounds and some hollows however suggest instead near surface ice or places where sublimation of that underground ice caused the hollows.

Some of the circular depressions might suggest impact craters, but if so, those craters have been significantly modified and softened since impact. Some do appear to be filled with glacial debris.
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