Tag: geology

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It might seem strange to call any particular place on Mars “barren” when the entire planet has no visible signs of life anywhere. However, much of the surface of Mars involves wind and ice features that show evidence of change and evolution over time. The presence of apparent near-surface ice and glacial features in almost every image located above 30 degrees latitude emphasizes this sense of potential life, even if that life will only be transported from Earth and established there someday by humans.

Today’s cool image to the right, cropped and reduced to post here, has none of these features. It is dry barren bedrock, with only a faint scattering of Martian dust indicated by many faint dust devil tracks.

The picture was taken on March 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The largest and most distinct flat-topped mesa in the image is only about 100 feet high, with the north-south ridgeline to the south about 20 feet high.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an avalanche that slumped downward out of the material that forms the interior western wall of an unnamed 25-mile-wide crater about 100 miles east of Gale Crater, where Curiosity has been roving for more than a decade.

The scientists call these types of Martian avalanches “mass-wasting events”, since the entire mass of the cliff moves downhill in a chunk, rather than as a pile of rocks that grows in size and strength as it picks up material on its way down.

It is not clear how old this slide is. A lot of the material on this slope appears to be Martian dust, some of which has flowed into the avalanche material after it had slide downhill.
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The cool image from Mars to the right, rotated, cropped, reduced, and sharpened to post here, provides us a good illustration of the lineated grooves that are typically seen on the surface of valley-confined glaciers, both on Earth and on Mars, and are also seen on the patched, grooved surface of Ganymede.

The picture was taken on March 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what appears to be a glacier flowing through a constriction. The arrow indicates the direction of the downhill grade.

The location, indicated by the white dot inside the inset on the overview map above, marks the location, in the western end of the 2,000 long northern mid-latitude strip on Mars I dub glacier country. In these three mensae regions (Deuteronilus, Protonilus, and Nilosyrtis) of chaos terrain practically every high resolution image shows features that resemble glaciers.

In this case, the glacial flow appears to be draining from a 10-mile-wide ponded circular valley though a narrow gap.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also rotated it so that north is to the top.

Labeled a “terrain sample” by the camera team, this picture 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 its proper temperature. As usual, when the camera team needs to do this, they try to pick a target of interest. Sometimes they succeed, sometimes not.

In this case, the picture is of a location only about 800 miles from the Martian north pole, on the northern lowland plains. While the section shown to the right focuses on the largest crater, the full picture includes a few others, all of which appear to have their interior floors cracking in the same way, and all appear to be pedestal craters, sitting above the surrounding terrain, though by not as much.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 16, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a pockmarked flat plain with a scattering of meandering hollows, each filled with ripple sand dunes that make these depressions resemble at first glance the tracks of tires.

Obviously, we are not looking at evidence of a past giant vehicle moving across the ground on Mars. The MRO science team labels these “fractures,” suggesting some past geological process caused the surface to crack in this manner, with those cracks widening with time due to erosion or sublimation.

The location of course tells us something about that process.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this a terrain sample image, which implies it was taken not as part of any specific request, but to fill a gap in the camera’s schedule in order to maintain its proper temperature.

What are we looking at? This stippled terrain with curved ridges actually extends quite a distance beyond this image. A MRO context camera picture taken on July 22, 2020 shows its full extent, about 10 miles wide but extending to the north and south about 30 miles total, butting up against a north-south mountain chain to its east that is about seventy miles long with its highest peak about 8,000 feet above this plain.
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The nature of today’s cool image suggests both ancient and more recent geological activity, each coming from entirely different sources but both helping to shape the alien Martian surface.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team has labeled an “elongated depression,” sitting in the middle of a relatively flat but very rough stippled circular plain about 60 miles in diameter. An MRO context camera picture, taken on February 19, 2012, covered the central strip of this plain, and shows that its surface is equally rough and stippled everywhere, with only a few craters and one or two slight changes in elevation.

So, how does this feature tell us both about the ancient and recent geological history of this spot on Mars?
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Today’s cool image from Mars is not so much unique visually as it is unique in terms of its location. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the northern rim of a small crater, with its floor filled with an intriguing mound of material.

The picture was labeled a “terrain sample”, which suggests it wasn’t taken as part of any specific research project by instead to fill a gap in the camera’s schedule. To maintain the camera’s proper temperature, it is necessary to take pictures regularly, and when the camera team finds a gap that is too long, they fill it by choosing some almost random target in that gap that might be interesting. Sometimes it is, sometimes not.

In this case I strongly suspect this target was hardly random. The picture title also mentions MRO’s now retired radar CRISM instrument, which was used to detect evidence of underground ice. My guess is that the camera team thus likely decided to image this crater in high resolution because that radar data suggested the presence of underground ice.

This guess is strongly confirmed by a context camera picture taken of this crater on September 1, 2008. The crater appears surrounded by the typical splash apron one routinely sees around impact craters in the mid- and high-latitude northern lowland plains, where there is a lot of near surface ice.

The bumpy mound seen in high resolution on the floor of this crater could very well be buried glacial ice, as it mimics similar features in the many craters in the mid-latitudes of Mars. But is it buried ice? The location says otherwise.
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Today’s cool image takes us to a part of the cratered southern highlands of Mars that I have not featured much previously. The picture to the right, rotated, cropped, and reduced to post here, was taken on March 7, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be a collection of rough hills and mesas surrounded by a sea of smooth ground that at the base of the cliffs seems to end abruptly.

The smooth ground is probably mantled by a layer of dust and debris. Since this location is at 36 degrees south latitude, there is also probably near surface ice under that layer. The abrupt edges likely indicate where the increasing slope next to the mesas and mounds caused that ice to be exposed and thus sublimate away.

As for the location, we must go to the overview map.
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Cool image time! The picture to the right, cropped to post here, was taken on February 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what the science team labels “regularly textured ground on Pavonis Mons.”

The arrow in the picture indicates the downhill trend. If you look at the full image, you will see that this texture pattern extends in all directions for a considerable distance, both uphill and down, and even covers the entire floor of a depression that appears to contour along the grade instead of going downhill.

The latitude here is very close to the equator. So, even though the elevation is high, being on the slopes of a giant volcano, there is probably no near surface ice here.
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Cool image time! The picture to the right, cropped to post here, was taken on February 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). This is a terrain sample image, which means it was snapped 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. As usual, the camera team tried to pick something of interest, and I think they succeeded.

The two large depressions in the center of the picture do not resemble impact craters. They have no rim of ejected material and their shape is very distorted. Instead, both appear to be places where a top layer of ice/debris has sublimated away into gas, exposing a lower layer of glacial material that itself is sublimating away to form the bumpy mounds that fill the floor of the depressions.

The white dot inside the inset box on the overview map above marks this location, just south of the northern wall of a large 30-mile-wide canyon, with its northern floor even more depressed, as if the material in that raised middle a flat pile of glacial debris flowing to the southwest after leaving the gap in the crater to the northeast. An MRO context camera picture taken on January 6, 2016 gives a wider view, showing that there are a lot of these type depressions on the surface of this wide middle upraised floor, as well as some obvious impact craters.

This location is in the mid-latitude band where many glacial features are found. In this part of the southern cratered highlands there is also a lot of evidence of top layers sublimating away, as if the glacial material is a large buried ice sheet that is beginning to disappear at places where it has been exposed by impacts or shifting motion. The depression in the picture above appears to be an example.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 28, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

To put it mildly this is strange terrain. The curving east-west feature resembles a glacial flow, but it also has features that say otherwise. For example, what could cause that gap in the middle of the picture? Such things are not usually seen in an ice flow. Then there is that filled crater on the center left edge of the picture, inside the flow. Though filled with material, the flow itself does not flow around the crater, suggesting the impact occurred after the flow. Moreover the crater is a pedestal crater, whereby the surrounding terrain has eroded away so that the crater ends up standing above it.

These facts suggest that this flow is very old, and has not flowed for a very very very long time. This in turn suggests it isn’t ice but solidified lava, though for a lava flow it also has features that are anomalous when compared to typical flood lava on Mars.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this a “Circular Outcrop of Bright Rock.

What I see is a Martian skin rash. Based on the ripple pattern below the ridge one might think we are looking at sand dunes, except that the rash above the cliff has no such pattern. Instead, the ground in this one particular area looks very roughened in a random sort of way.

The location at 27 degrees south latitude suggests there is little near surface ice at this location to cause this feature. The overview map below provides another but not very helpful possibility.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 7, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the camera team labels a “sinuous ridge within valley.”

The location is at 30 degrees south latitude, right on the edge of the southern of the two 30-60 degree mid-latitude bands where orbital images show many glacial features. Closer to the equator and there is little or no evidence of near surface ice on Mars. Farther from the equator from this latitude and the evidence of near surface ice increases, becoming very dominant the closer to the poles you get.

At this spot, it appears there is little near surface ice. The channel has ripple sand dunes inside it, and the sinuous ridge appears to be bedrock. Similarly, the plateau above the channel also appears like bedrock, the craters showing no evidence of splatter that is common where there is near surface ice.

What made the channel? And what made that a sinuous ridge inside it?
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on March 26, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is labeled by the scientists “Brain Terrain on Floor of Crater in Warrego Valles.”

Brain terrain is a geological feature entirely unique to Mars that remains unexplained in any way by geologists. The scientists know it is almost certainly related to near-surface ice and its sublimation into gas, but their theories as to its precise formation process remain incomplete and unconvincing, even to them.

In this case the brain terrain’s interweaving nodules seem to show flow patterns, but strangely those patterns go around depressions and hollows. Yet, the overall flow direction also seems to point downhill towards the slope on the image’s right edge.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) by the camera team not as part of any particular research project but in order to fill a gap in the camera’s schedule so as to maintain its proper temperature. In such cases the camera team tries to pick potentially interesting spots.

This cliff, about 1,100 feet high, is the north wall of a major volcano channel flowing across the Tharsis Bulge, the lava plains that surround Mars’ giant volcanoes. Located in the dry equatorial regions, there is no near surface ice here, but a lot of dust, much of it likely volcanic ash. In the full picture are several ancient craters, all of which are almost entirely buried by this dust and ash.

The cliff wall itself is made up of numerous layers, each representing a past volcanic flood lava event that covered this region with a new flow of material. These events occurred over more than a billion years.
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