Tag: geology

Cool image time! Today’s cool image begins with the overview map to the right. The white dot marks its location, on the western edge of Amazonis Planitia and about 1,000 miles east of the giant shield volcano Elysium Mons.

This is a region of numerous flood lava events that appear to cover the knobby mountainous terrain that was once here. We know that past terrain was knobby because in the black outline just south of this picture the knobs are everywhere, short peaks sticking up from a very flat flood lava plain. The region is also on the northern edge of the dry equatorial regions of Mars, at 27 degrees north latitude. It is likely there is little near surface ice here.

These details will help explain the cool image itself.
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Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on March 25, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this image “Cross-Section of Glacier-Like Form,” probably because the mesa in the center of the picture clearly shows numerous layers as you descend from its peak to the surrounding plains, an elevation difference of about 200 feet.

The white dot about 250 miles due south of Lyot Crater on the overview map above marks the location of this mesa, inside the chaos terrain of Deuteronilus Mensae that is the western section of the 2,000 long strip in the northern mid-latitudes of Mars that I call glacier country, since practically every image, like today’s, suggests the presence of glaciers.

The oblique mosaic below, created using MRO’s context camera images, illustrates this fact even more spectacularly.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on April 28, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Dubbed a “terrain sample” by the camera team, 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 that camera’s proper temperature. When they have to do this, they try to pick interesting targets, though there is no guarantee the result will be very interesting.

In this case the camera snapped what appears to be a drainage channel between two deeper hollows. The channel sits about 100 feet above the western hollow and 260 feet above the eastern hollow. This makes some sense, as the overall drainage in this region is going from the west to the east, and then to the north.
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Cool image time! The picture to the right, enhanced, cropped, reduced, and sharpened to post here, was taken on April 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels as “Rough Ground and Bright Exposures” on the flanks of a wide mountain range on Mars, whose highest point is about 4,400 feet higher to the northeast and about 30 miles away.

The arrow indicates the downhill grade. Notice the smooth flat areas that seem to only partially cover much rougher terrain below. To my eye this top layer resembles an Earth glacier that has partly sublimated or melted away, exposing the rougher bedrock below that has been ground and scraped by the glacier previously.

However, this is not on Earth, so assuming it is like an Earth glacier is dangerous.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this a “Terrain Sample”, which suggests but doesn’t guarantee that it was to fill a gap in the camera’s schedule in order to maintain that camera’s proper temperature, and therefore was targeted at a relatively random but potentially interesting location.

What we see is a fissure canyon, about 250 to 300 feet deep with cliffs about 125 high, that appears surrounded and even filled with icelike features. Even the craters on the plateau above the canyon appear like they either impacted in ice, or have since been filled and eroded by that ice.

But is it ice?
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels “Mantle Layers in Southern Mid-Latitudes.”

I would be less vague. These strangely shaped features invoke the typical glacial features seen throughout the mid-latitudes of Mars. The knobs and outcrops suggest some underlying breakdown that the top layers of glacial material has covered. They also suggest some form of sublimation or erosion process to the glacier itself.

The white rectangle inside the inset on the overview map above marks this location, covering the floor of an unnamed 10-mile-wide crater in the cratered southern highlands at 41 degrees south. In this region all the craters show some evidence of this sublimation, all suggesting that there is a near-surface underlying ice layer that when exposed vanishes to leave depressions or hollows. Here however it appears that ice layer is mostly intact, the knobs and ridges indicating the shape of the bedrock and large breakdown below.

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Today’s cool Mars image is especially cool because it is of the exact same place on Mars I had featured in a picture only a little more than one month ago. I return to this spot only a month later because the location was yesterday’s featured captioned image from the high resolution camera team of Mars Reconnaissance Orbiter (MRO). The difference is that this time the camera captured a dust devil there that wasn’t there previously. From the caption:

The dust devil is casting a shadow, which can be used to estimate its height. This image is part of ongoing monitoring activities by HiRISE of seasonal activities on Mars.

Over the years, HiRISE has observed many dust devils. Just like on Earth, dust devils develop when the Sun heats up the ground such that it warms the air directly above it. When air heats up its density decreases causing it to rise up while colder air sinks down driving local convection.

If the region is windy, the wind my end up rotating the “convection cells” caused by the vertical motion of air leading to development of a dust devil. Since the main requirements for development of such features are the presence of dust and a warm ground, we focus our monitoring of dust devils in regions on Mars that are known to be dusty (like Syria Planum), and during the late spring and summer time, when we expect the ground to be warm.

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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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