Tag: MRO

More thumbprints on Mars!

1:22 pm

Thumbprints on Mars
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Cool image time! Among the many strange and unexplained geological features that scientists have identified on Mars, the thumbprint feature is one of the most intriguing. The photo to the right, cropped and reduced to post here, is a fine example, and was taken on September 10, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The thumbprints are the lighter splotches, and are generally found near curved ridges located mostly in Martian lowlands. All appear to have crater-like features in them, though these craters are not impact craters, but likely (though not confirmed) caused by some form of underground eruption, be it mud, ice, lava or something else. Though scientists do not yet really understand the process that formed the thumbprints, the data strongly suggests that they formed in connection with glacial events. From this 2003 paper [pdf]:

TT [thumbprint terrain] as well as the associated trough systems were formed by a glacial mechanism. [Elevation] data show that the trough systems consistently lie topographically above the TT; this implies that if they were they formed by the same glacier, the troughs must have formed before the glacier retreated and formed the TT.

The splash apron around the crater near the bottom of the photo supports the glacial theory, implying the presence here of underground ice.

Scientists have also theorized wind processes and cinder cones as explanations for these features.

These particular thumbprints are located, as shown in the overview map below, in the same general area as a previous cool image of thumbprints, from April 2019.
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Monitoring one glacier flowing off a mesa in Mars’ glacier country

1:28 pm

Vicous glacial flow on Mars
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Today’s cool image takes us back to the mesa in Mars’ glacier country that first clued me in on the prevalence of ice in the Martian mid-latitudes. The photo to the right, rotated, cropped, and reduced to post here, was taken on November 13, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a viscous flow coming down from a hollow on that mesa’s southern wall.

The new image has likely been taken to see if anything has changed since the previous image was taken in 2014. Based on the resolution published at the MRO website, nothing seems to have changed, though with more sophisticated software higher resolution versions of the images are available that might show some changes.

In my first post about Mars’ glacier country in December 2019, this flow was one of four that I featured coming off this same 30-mile wide mesa, as shown by the first overview map below.
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Fractured terrain on Mars

1:39 pm

Fractures on Mars
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Today’s cool image, which at first glance does not seem so puzzling, actually falls into my “What the heck?” category of baffling Martian geology. The picture to the right, cropped and reduced to post here, was taken on January 15, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled “Avernus Cavi fractures”, it shows what resembles the well-documented chaos terrain seen in many places on Mars, where erosion over eons along fault lines creates mesas with random criss-crossing canyons.

The problem is that this location is practically on the Martian equator, and chaos terrain tends to be found in the mid-latitude bands where there are many glaciers, suggesting the cyclical waxing and waning of those glaciers is what causes the erosion. Here at the Martian equator the terrain is very dry. No glaciers.

Moreover, note the higher mesa near the top center. Its flat top suggests that once this terrain was covered with an even higher layer of material, almost all of which was stripped away evenly everywhere, except where that mesa sits. As an amateur geologist I can’t think of any sequence of events that would do such a thing. I suspect professionals might have problems themselves.

Then there are the small parallel ridges. They suggest dunes, especially inside the depressions where sand and dust can get trapped. On the mesa tops however these ridges are more mysterious. Why for example are they aligned with the small ridge in some hollows, but not others? They in many ways remind me of the ridges in this earlier “What the heck?” cool image, also right on the equator.

The overview map below provides some help, though not much.
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The layered Martian history exposed in Valles Marineris

12:28 pm

Overview map

The layers in Valles Marineris
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Cool image time! Like the Grand Canyon in the United States, Mars’ largest canyon, Valles Marineris, appears to have been carved out of a layered terrain, thus exposing those many layers in the walls of the canyon.

Valles Marineris, however, is much much larger than the Grand Canyon. You could fit dozens of Grand Canyons inside it and hardly fill it. Yet, its walls have the same layered look, suggesting that in Mars’ long geological history, first came many events that laid down new layers time after time, followed by a long period when the laying ceased and other events carved out the canyon to its almost 30,000 foot depth (which by the way is also about six times deeper than the Grand Canyon).

Today’s cool image to the right, cropped and reduced to post here, was taken on September 5, 2021 and shows a terraced terrain on the floor of Candor Chasma, one small side canyon of Valles Marineris that is still much larger than the Grand Canyon. The black dot in the overview map above indicates its location. I roughly estimate the elevation difference between the high and low spots in the picture is about 3,000 feet, a difference that while two-thirds that of the depth of the Grand Canyon is almost unnoticeable within the depths of Valles Marineris.

This layering is probably the canyon’s most important geological feature. See these previous cool images here and here for other examples. When geologists finally arrive on Mars and can begin dating these layers in detail they will likely reveal the planet’s entire geological history, going back five to six billion years.

Most of the layers are probably volcanic flood lava laid down by repeated eruptions from the giant volcanoes to the west. In between and within however will be deposits from the Martian atmosphere, telling us its composition and thickness. All told, the layers of Valles Marineris will likely unlock almost all of the most basic secrets of Martian geology.

We merely have to go there to find out.

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Martian crater overwhelmed by glacier?

1:32 pm

Martian crater overwhelmed by glacier?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on January 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter. It shows what the science team labels a “modified crater.”

What I see is an old crater almost completely covered by glacial material. That material however is also very old, as there are numerous small craters on its surface, enough that it must have been here for a long time. Its cracked surface also suggests this glacier is very old.

Thus, while we might have ice here, buried by a thin layer of dust and debris to prevent it from sublimating away, it must be very old ice. The many climate cycles caused by the extreme swings in Mars’ rotational tilt, from 11 to 60 degrees, have apparently not caused this ice to ebb and flow very much.

Might it therefore not be ice, but hardened lava?

The location, as shown by the overview map below, provides some context, but only makes this mystery more puzzling.
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Scientists: Martian topography in one region suggests the past existence of lakes and river networks, but not a large single ocean

3:53 pm

Based on a just published paper, scientists using orbital topography data and imagery have concluded that more than three billion years ago on Mars ancient rivers in the transition zone between the southern cratered highlands and the northern lowland plains fed into numerous lakes in the lowlands, not a single large ocean as some scientists posit.

From their abstract:

The northern third of Mars contains an extensive topographic basin, but there is conflicting evidence to whether it was once occupied by an ocean-sized body of water billions of years ago. At the margins of this basin are the remnants of deltas, which formed into water, but the size and nature of this water body (or water bodies) is unclear, and detailed investigations of different regions of the basin margins are necessary.

In this study, we use high-resolution image and topographic datasets from satellites orbiting Mars to investigate a series of water-formed landforms in the Memnonia Sulci region, set along the boundary of Mars’s northern basin. These landforms likely formed billions of years ago, providing evidence for ancient rivers and lakes in this region. The geologic evolution of these rivers and lakes was complicated, likely influenced by water-level fluctuations, changes in sediment availability, and impact cratering. Our topographic analysis of these rivers and lakes suggests that they terminated in a series of ancient lake basins at the boundary of Mars’s northern basin, rather than supplying a larger, ocean-sized body of water. [emphasis mine]

Overview map

The Memnonia Sulci region is in the cratered highlands just south of the Medusae Fossae Formation, the largest volcanic ash deposit on Mars. The region of study in it is marked by the blue dot in the overview map to the right.

The study does not preclude the possible existence of a northern ocean on Mars, but it says that at least in this region at the equator, it did not exist. Instead, the various river valleys drained into separate smaller and relatively short-lived lakes.

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Dry barren ground in Martian northern lowlands?

3:38 pm

Dry barren ground in the Martian northern lowlands?
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Today’s cool image is intriguing because of what appears to not be there, rather than what is there. The photo to the right, cropped and reduced to post here, was taken on November 3, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

At first glance it appears to show a very dry, barren surface. At its base are many parallel grooves running from the southwest to the northeast. On top of these grooves are several more recent crater impacts, as well as several patches of higher bedrock that appears to have been hard enough to resist whatever erosion process caused the groves.

Yet, based on the overview map below, the location of this photo should not be dry and barren, but instead home to a near-surface ice sheet covering everything.
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Deformed Martian craters

2:04 pm

Deformed Martian craters
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Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on September 3, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The focus of the image for the MRO science team were the wedding cake layers inside the largest crater. These layers suggest glacial ice, with the layers suggesting multiple cycles of glacial ebb and flow. Since the crater is at 43 degrees north latitude, and sits in the chaos region dubbed Protonilus Mensae, smack dab in the center of what I call Mars’ glacier country, this conclusion makes perfect sense.

To my eye, however, the most interesting feature of this photo are the many distorted craters. The overview map below shows the picture’s location, as well as several nearby very large impact craters which might have caused many secondary impacts, including the many craters at this location.
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Cracking ice on Mars?

12:43 pm

Cracking ice on Mars?
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on December 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the MRO science team dubs “erosion of scalloped terrain” in the northern lowland plains of Mars.

The cracks invoke the polygon cracks one sees in mud as it dries. The circular feature suggests a buried crater whose shape is merely suggested because the cracks are conforming to the underground topography.

Are we looking at dried mud? Maybe, but more likely we are seeing a sheet of ice now sublimating away and cracking as it does so. If you look at the full photo you will see the cracked material also appears to drape itself over several nearby low ridges, something that seems more likely from ice than mud.

The overview map below also suggests this is a buried layer of ice.
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Mars: Glaciers on top of glaciers on top of glaciers

1:16 pm

Overview map
Mars’ glacier country.

glaciers on top of glaciers on top of glaciers
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on December 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small patch of layered glacial features flowing in all directions. The overview map above marks its location by the red dot, at 40 degrees north latitude in the region dubbed Deuteronilus Mensae, on the western end of the 2,000 long strip from 30 to 60 degrees north latitude that I dub Mars’s glacier country because practically every image in this region shows glacial features.

What makes the glacial features in this picture so remarkable is their number, their somewhat chaotic nature, and the evidence of many layers, suggesting a cyclical process of ebb and flow over the eons.

Below I zoom into one section of this photo, showing that section at full resolution.
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Random Martian ridges on a lava plain

1:02 pm

Random ridges on Martian lava plain
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on December 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). This was a terrain sample image, taken not as part of any specific research project but to fill a gap in the camera’s schedule and thus keep its temperature maintained properly. When the MRO team needs to take such pictures, they try to pick locations that might be interesting and previously unphotographed, but often the location is neither.

In this case this terrain sample captured a flat lava plain interspersed with sinuous ridges going in all directions. On top of this is a scattering of smaller impact craters, which obviously occurred after the lava had flowed and solidified.

What caused the ridges?
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Hot spot in northern Martian crater?

12:18 pm

Hot spot in northern Martian crater?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on September 22, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an unnamed four-mile-wide crater in the high northern lowland plains of Mars, at 60 degrees north latitude.

At 60 degrees latitude, it is likely that the crater’s interior is filled with buried glacial ice. A close look at the crater’s interior rim shows that whatever material fills the crater does not quite reach the rim. Furthermore, there are areas in the interior where it appears some slight sublimation has occurred. These features suggest the interior material is buried ice, but do not prove it.

What makes this crater intriguing however is the irregular depression at its center. When craters have a feature at the center, it usually is a central peak, caused at impact. The impact makes the ground act like a pond of water when you drop a pebble into it, with circular ripples (the crater rim) spreading outward and an uplift in the center (the central peak). In the case of a crater, the pond quickly freezes, locking those ripples and uplift in place.

Why a central depression then?
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When looking at Mars’ images you must never jump to conclusions

1:16 pm

Hardened sand in a crater
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In the past four years I have posted hundreds of cool images taken by the orbiters circling Mars. From those images I have been able to slowly gather and pass on to my readers some of the solid knowledge that scientists are gaining now about the Red Planet.

The image to the right illustrates best why one must never make any quick assumptions about the features you see in these photos. Taken on November 28, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows a small crater that appears partly filled with material. On its walls can be seen many slope streaks, a still unexplained feature unique to Mars that is not caused by rock or debris avalanches.

As for the material inside the crater, based on the majority of Martian images showing similar craters, the first assumption one might make is that this material is some form of eroding glacial material.

That first assumption however would simply be wrong. Glacial material found in Martian craters is routinely found in the mid-latitude bands between 30 and 60 degrees. This crater is sits almost exactly on the equator of Mars, where scientists have found no evidence of any glacial material or near-surface ice. In the equatorial regions the surface of Mars is essentially dry.

So what is that patch of material? As always, location is all.
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Glaciers in the Phlegra Mountains on Mars

1:42 pm

Glaciers in the Phlegra mountains
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Cool image time! The photo to the right, cropped to post here, is just one of the many hundreds taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) as well as Europe’s Mars Express orbiter showing the thick icy glacial flows that surround practically every mountain or hill in the Phlegra mountains of Mars.

This picture was taken on November 3, 2021, and shows the eroding foot of an eroding glacial flow coming down from a small hill in a southeastern part of these mountains dubbed Phlegra Dorsa. The downward grade is to the north.

At 30 degrees north latitude it is not surprising these glacial flows are eroding, as they are at the southernmost limit of the mid-latitudes bands where such glaciers are found. Closer to the equator scientists have yet to find much evidence of ice.

The repeating arcs at the foot of this glacier suggest that it pushed downward in cycles, with each later cycle traveling a shorter distance. This supposition makes sense, considering scientists think the ebb and flow of these Martian glaciers has been determined by the cyclical changes in the planet’s rotational tilt.

The overview map below not only gives the context, it shows this location relative to the candidate landing sites for SpaceX’s Starship spacecraft.
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Scientists: Liquid surface water might have existed on Mars as recently as 2.3 billion years ago

10:00 am

Map showing locations of salt deposits
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Using orbital data from Mars Reconnaissance Orbiter (MRO), scientists have found salt deposits on Mars where nearby crater counts suggest that the salt water that once held these deposits could have evaporated away as recently as 2.3 billion years ago.

Using [MRO’s] cameras to create digital elevation maps, Leask and Ehlmann found that many of the salts were in depressions – once home to shallow ponds – on gently sloping volcanic plains. The scientists also found winding, dry channels nearby – former streams that once fed surface runoff (from the occasional melting of ice or permafrost) into these ponds. Crater counting and evidence of salts on top of volcanic terrain allowed them to date the deposits.

Past data has suggested that if liquid surface water had existed on Mars, it was gone by three billion years ago.

You can read the scientists’ research paper here.. The maps to the right, figure two from the paper, shows the locations of discovered salt deposits, almost all of which are in the Martian southern cratered highlands of Mars.

Is there uncertainty in these results? My regular readers know that the answer is of course yes. The biggest problem for these Mars researchers is that, despite the surface evidence that liquid water should have once flowed on the surface of Mars, no scientist has yet come up with a satisfactory model of Mars’ past climate that would have made that possible. The planet was either too cold or had too thin an atmosphere, based on other data. And getting it warmer or with a thicker atmosphere involves inventing any number of scenarios that are all questionable, based on what is presently known.

There is also the increasing evidence that glaciers of ice, not water, might have carved those winding, dry channels. If so, many of the assumptions that liquid water existed might simply be wrong, or incomplete. The scientists who wrote this report recognize this importance of ice on Mars, and note in their abstract that

…we think that the water source came from surface runoff, rather than deep groundwater welling up to the surface. The small amounts of water required are most likely from occasional melting of ice.

As always, more data is needed, with the most useful data that will clarify these conclusions being that gathered by future colonists on the surface of Mars itself.

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Mars’ youngest lava flow

1:41 pm

Mars' youngest lava flow
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Today’s cool image is in some ways another version of my last cool image yesterday. Both are in Mars’s volcano country. Both show what appears to be a lava flow.

Yesterday’s image showed the leftover evidence of a confined flow of lava running in a meandering pattern like a river, and was somewhat distant from the biggest nearby volcanoes. Today’s cool image, to the right and rotated, cropped, and reduced to post here, is instead located smack dab on the inside of what is thought to be Mars’ youngest major lava event, the Athabasca flood lava plain, and in fact is near its outlet, when about 600 million years ago it belched out enough lava in just a matter of a few weeks to cover an area about the size of Great Britain.

The overview map below illustrates this.

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Freaky badlands on Mars

1:20 pm

Freaky badlands on Mars
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Cool image time! The photo to the right, rotated and cropped to post here, was taken on November 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as “Danielson Crater Outcrops,” it shows us a perfect example of the strangeness and sometimes very forbidding terrain of Mars.

We are looking at the outcrop tops of many tilted layers, worn into curves semicircles with the convex side all pointing to the southwest. In the hollowed concave-side, dust and sand have accumulated and been trapped, sometimes forming small ripple dunes when there is enough space for the wind to get inside, as seen in the picture’s lower right.

Danielson Crater is 41 miles in diameter. The overview map below provides the context.
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A cracking and collapsing glacier on Mars

12:18 pm

Fractured ice sink hole on Mars?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on November 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small portion of the floor of a very ancient and eroded unnamed 40-mile-wide crater on Mars.

MRO’s science team labeled this picture simply as a “Fractured Feature.” The section I have focused on in the cropped image is clearly the fractures the scientists were interested in. What is heck caused this?

The location is at 39 degrees north latitude and is located at the very western end and in the center of the 2,000-mile-long mid-latitude strip I call glacier country because practically every photo exhibits evidence of glaciers. Thus, this fractured terrain is almost certainly evidence of ice that partly buried and thus protected from sublimating away.

The collapse feature indicates more, however. The circular shape of the fractures suggests that the center of this feature is sinking, with the ice on all sides slipping downward and breaking as it does so. The location however is not in the center of this crater, but near its southern interior rim. Moreover, in a wider image from MRO’s context camera this feature appears to be within what looks like a thick patch of ice filling most of the southeast quadrant of the crater. On it are other similar collapse features.

The data suggests that this ice patch is eroding, but doing so influenced by the rough terrain on which it sits. The sinks suggest the glacial ice is sublimating first over low spots, but this is hardly certain.

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Scientists discover that mid-sized dunes near Mars’ north pole move

11:41 am

Mars' North Pole

Scientists using images from Mars Reconnaissance Orbiter (MRO) collected over six Martian years (6.5 Earth years) have found that the mid-sized dunes dubbed mega-dunes near the north pole actually do move from year to year, unlike similar sized dunes elsewhere on the planet.

Megaripples on Mars are about 1 to 2 meters tall and have 5 to 40 meter spacing, where there size falls between ripples that are about 40 centimeters tall with 1 to 5 meter spacing and dunes that can reach hundreds of meters in height with spacing of 100 to 300 meters. Whereas the megaripples migration rates are slow in comparison (average of 0.13 meters per Earth year), some of the nearby ripples were found to migrate an average equivalent of 9.6 meters (32 feet) per year over just 22 days in northern summer – unprecedented rates for Mars. These high rates of sand movement help explain the megaripple activity.

Previously it was believed that such dunes were static planetwide, left over from a time when Mars’ atmosphere was thicker and could then move them more easily. This data however suggests that the winds produced over the north pole when the carbon dioxide in the atmosphere freezes in winter and sublimates back to a gas in summer are sufficient to shift these dunes in the surrounding giant Olympia Undae dune sea.

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Strange land forms on the flanks of Mars’ Arsia Mons volcano

1:24 pm

Strange landforms on the flanks of Arsia Mons
Click for original image. Click here for the context camera image.

Cool image time! The center of the photo to the right was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on September 5, 2021. For posting here I have rotated, cropped, and reduced it, as well as added to each side the lower resolution context camera image of this region.

The ground slopes downhill to the north. Make sure you click on the image to see the full resolution version. In only a few miles the terrain changes from a mound with small knobs to a smooth area with few knobs to a chaotic area where the larger ridges and knobs are the dominant feature, with hollows and canyons in between.

You should also take a look at the full context camera image. Just to the southeast of the above picture is a large depression that looks like it has been filled with lava, with its western rim covered by that flow. Scientists have taken a lot of high resolution pictures of this depression with MRO, trying to decipher its geology.
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A Martian cliff

1:30 pm

A strange Martian cliff
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Many features on Mars immediately make one think of the Grand Canyon and the stark dramatic geology of the American southwest. Today’s cool image on the right, cropped and reduced to post here, is a typical example. Photographed on September 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows a dramatic cliff face that I estimate is about 3,000 feet high.

A closer look, however, almost always shows that this Martian terrain is not like the American southwest at all, but alien in its own way.

At the base of this abrupt cliff the terrain suddenly changes to a series of smooth downward fan-shaped flows. The cliff evokes rough boulders, avalanches, and chaotic erosion. The fans evoke a gentle and organized erosion of small particles like dust or sand. The two processes are completely different, and yet here the former is butted right up against the latter.

The fans also appear to flow out of hollows in the rough cliff, suggesting that somehow as the cliff erodes in chunks those chunks break into sand or dust, find the lowest points, and then flow downward like liquid.

How strange. How Martian. And how truly beautiful.

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Ice-filled crater on the Martian north polar ice cap

2:15 pm

Ice-filled crater on the Martian north pole ice cap
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Cool image time! The photo to the right, cropped to post here, was taken on September 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a very distinct impact crater on top of the layered deposits of ice mixed with dirt that form the bottom layers as well as surround the visible north pole ice cap on Mars.

I purposely cropped the high resolution image so that the crater is off center to show the dark streaks that appear to blow away from the crater to the northwest, west, and southwest. This asymmetric pattern suggests the wind direction at this location generally flows to the west, but the pattern might also be caused by lighting effects. The location is at 82 degrees north latitude, and the Sun was only 31 degrees high when the picture was taken, causing long shadows. Also, in the full image, you can see a whole strip of similarly oriented streaks, suggesting that these are slope streaks descending a slope going downhill to the northwest.

The overview map below also provides important information about this location.
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Ice canyons at the Martian north pole

1:46 pm

Ice canyons at the Martian north pole
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on July 24, 2021 by the high resolution camera of Mars Reconnaissance Orbiter (MRO) and shows one small portion of the edge of Mars’ north pole ice cap.

The many layers in that ice cap are clearly evident, with some darker because they were probably laid down at a time when the Martian atmosphere was more filled with volcanic ash. According to the presently accepted theory, the layers show the cyclical climate patterns of Mars, caused by the large shifts in its obliquity, or the tilt of the planet along its rotational axis, ranging from 11 to 60 degrees. Presently Mars is tilted 25 degrees, similar to Earth’s 23 degrees. The two extremes cause the planet’s water ice to shift back and forth from the mid-latitudes to the poles, causing the layers.

The height of this layered cliff face is probably about 1,500 feet, though that is a very rough estimate. Notice also that this image shows an ice canyon running from the left to the right and flowing into a much larger ice canyon to the right. The top cliff is probably about a third the height of the bottom cliff.

The overview map below shows gives the context, not only in place but also in time.
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The badlands on the floor of Valles Marineris

1:03 pm

The badlands on the floor of Valles Marineris
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Cool image time! The recent discovery that there might be a near surface reservoir of ice on the floor the canyon Valles Marineris, near the Martian equator, immediately brought this location to the forefront as a possible site for establishing colonies. The weather will be less harsh than higher latitudes, the low elevation means a thicker atmosphere, and the terrain will be more appealing than the boring flat northern lowlands.

The picture to the right, cropped and reduced to post here, illustrates however the likely difficulties of landing and living on the floor of Valles Marineris. Taken on July 26, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the photo shows just one small area of the floor of Ius Chasm, the western part of Valles Marineris and about 300 miles to the east of that water reserve.

In this one picture we can see trapped sand dunes in hollows, eroded depressions, mottled terrain resembling stucco, and innumerable cliffs and sinks and plateaus. For the first manned spacecraft to land on Mars, this is not a good first choice. Even later, when the first bases have been built, this terrain would still be forbidding for the early colonists to land in and traverse.

The overview map below shows exactly where this picture is relative to the rest of the Valles Marineris.
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Slope streaks in frozen lava flows on Mars

12:30 pm

Slope streaks on frozen lava
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 5, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a ridgeline at the base of the giant volcano Pavonis Mons, with slope streaks on ridge’s north and south sides.

Slope streaks are a mysterious phenomenon unique to Mars. While they resemble an avalanche, they do not change the topography of the surface at all. They appear to occur randomly year round, fading slowly with time. Also, while most are dark, scientists have also spotted bright slope streaks as well.

Slope streaks also only appear on surfaces covered with a layer of fine dust, something that is obviously the case in the cool image to the right. There is so much dust on the surface here that bedrock only appears at the top of the ridge, peeking out in only a few places.

The location of this image, as shown in the overview map below, adds some additional details.
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Cracking glaciers on Mars

11:47 am

Cracking glaciers on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was released today as the picture of the day for the high resolution camera on Mars Reconnaissance Orbiter (MRO). Located in the 2,000 long northern mid-latitude strip that I dub Mars’ glacier country, it shows many of the numerous glacial features that are routinely found in images taken in this region. According to Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who wrote the caption,

This observation shows a lobe-shaped debris apron emanating from a massif (shown in the upper left of the image) in the Protonilus Mensae region in the Northern Hemisphere of Mars. These aprons are composed of nearly pure water ice with a layer of debris on the surface protecting the ice from sublimation (going directly from a solid to gaseous state). This image shows different terrain types on the apron that indicate the presence and flow of ice, from smoother polygonal terrain closer to the massif, to rougher, patterned ground commonly called “brain terrain.” Also visible on the apron are a series of linear pits.

Protonilus Mensae is the central mensae region in that mid-latitude strip of glaciers.The overview map below shows the location of this photo in that region. Also below is a close-up of the linear pits and cracked terrain surrounding that oblong mound, as indicated by the white rectangle.
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Visible clean water ice on Mars

11:57 am

Crater with ice scarp
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, is today’s picture of the day for the high resolution camera on Mars Reconnaissance Orbiter (MRO). Taken on September 13, 2021, it shows an exposed scarp on the southern inner wall of a small 800-foot-wide crater.

What makes that scarp intriguing is its blue color. As noted by Shane Byrne of the Lunar and Planetary Lab University of Arizona, who wrote the caption:

This north-facing cliff appears to expose icy material that’s similar to other pole-facing scarps showing buried ice elsewhere on the planet. These cliffs give us a cut-away view of the buried ice in that location and can help answer questions about what the Martian climate was like when this ice formed.

The crater itself sits inside a much larger crater, as shown in the wider picture below.
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Strange eroded glacial flows in unnamed crater on Mars

12:20 pm

Eroded glacial flows in unnamed crater on Mars
Click for full resolution image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on November 1, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a series of strange glacial-like flows coming off the western slopes of the central peak of a 40-mile-wide unnamed crater, located smack dab in what I call Mars’ glacier country, that 2,000 long mid-latitude strip where almost every image shows evidence of glaciers.

The cropped section to the right doesn’t really do these strange flows justice. Make sure you click on the image to see the full resolution version. There are numerous separate flows coming off that central peak. Each appears to show that as time passed, each flow traveled a shorter distance down the mountain, leaving a moraine behind at higher and higher points.

The overview map below provides the context.
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Sculptured lava south of Olympus Mons?

10:51 am

Sculptured lava?
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Time for a cool image! The photo to the right, rotated, cropped, and reduced to post here, was taken on September 8, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a region of strangely sculptured terrain located several hundred miles south of Olympus Mons.

It appears the prevailing winds are to the west. The question is whether the wind is shaping a hard lava surface, over eons, or is shaping instead layers of dust or volcanic ash quickly and seasonally. At this location either is possible. In fact, we might even be seeing evidence of both at the same time.

The overview map below shows that the location is just outside the Medusae Fossae Formation, the largest volcanic ash deposit on Mars.
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Volcanic vent on Mars

2:43 pm

Overview of Arsia Mons pits

To understand today’s cool image we really should start from a distance and zoom in. The overview map to the right focuses in on the two southernmost giant volcanoes in the string of three that sit to the east of Mars’ biggest volcano, Olympus Mons, and to the west of the planet’s biggest canyon, Valles Marineris.

The black dots mark the locations of the many high resolution photos taken by Mars Reconnaissance Orbiter that I have featured previously on Behind the Black. Many are isolated openings with no related geological features. Others appear to be skylights into a more extensive lava tube, hinted at by either a continuing surface depression or a series of similar skylights.

The white dot marks the location of today’s cool image, about 350 miles south of Arsia Mons’ caldera.
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