Tag: geology

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Time for another “What the heck?” cool image! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 23, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels as “longitudinally aligned cones”.

To my eye the cones visibile in this picture seem more aligned latitudinally, to the east-west, instead of longitudinally, north-south, but the larger view in the inset on the overview map below shows that on a larger scale, the cones do appear aligned in a north-south direction.

Either way, this is one of those photos from Mars orbit that leaves me entirely baffled. The cones and the flow feature that cuts across the middle of the image might be either volcanic or glacial, but it is beyond my pay grade to explain what caused this patch of aligned cones.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 22, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The picture’s focus of study is the bright strip running diagonally across the center, which the scientists label as a “linear feature exposure of infrared-bright material.”

This bright strip with all the swirls of alternating light and dark terrain is a fissure about 80 feet deep. What is interesting is that the parallel bright features to the north and south are actually ridges, not depressions, even though there appears to be some resemblance between them all. (Note that the patches of very thin parallel lines are likely ripple dunes sitting on top of the topography.)

So, what created this fissure? And why is its inner surface so strange? As is usually the case, a wider look provides some clues.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 16, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this as “gullies previously identified in the walls of Harmakhis Vallis.” The gullies are obvious, the series of erosion features on the cliff wall. The cliff itself drops about 2,800 feet from the rim to the floor, and also appears to have internal horizontal layers that the gullies cut through.

What causes the gullies? Planetary scientists have a number of theories, none of which appear to explain the gullies everywhere on the Martian surface. They all appear in the mid-latitudes, where the most glaciers on Mars are found, and appear to be related to ice or frost freeze-thaw processes, with some gullies actually very ancient and formed when the planet’s rotational tilt was significantly different.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 13, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the MRO science team labels as “streamlined features”, though that doesn’t seem to me to be the best description.

Granted, the prevailing winds, from the northeast to the southwest, appear to pushing the sand dune fields to the southwest. The dark line — created recently by a dust devil — indicates the wind direction. The mesas, from 100 to 200 feet high, do not however appear very streamlined. Instead, they simply look like they are poking up through this sea of sand and dunes, with the wind able over time to successfully push that sand uphill a hundred-plus feet into the saddle between the mesas.

The overview map below provides some context and possibly an explanation, though not a very conclusive one.
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Cool image time! The picture to the right, cropped to post here, was taken on July 1, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image is labeled simply as a “terrain sample,” which usually means it was taken not as part of any specific research project but to fill a gap in the picture-taking schedule in order to maintain the camera’s proper temperate. When the camera team needs to do this, they try to picture interesting features availabe at that time slot. Sometimes the image is boring. Sometimes it is surprisingly interesting.

In this case the picture is the latter, and certainly quite alien. The curly parallel dark lines appear to be grooves, and seem to have ripple dunes within them, as if the only dust here got trapped in those low spots. It is also possible that the dunes are frozen and ancient, and are only being revealed as the top layer in each groove goes away.

What could possibly explain what we are looking at? The overview map below gives only a clue.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 11, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a nice collection of what the scientists label “irregular ring structures,” interspersed with clusters of small mesas ranging in heights from 13 to 75 feet.

The location is at 27 degrees north latitude, so the presence of near surface ice, which might explain these strange rings, is less likely though not impossible. The stipled nature of the flat ground suggests that near surface ice might be here, resulting in sublimation of that ice and leaving behind a flat but rough surface.

The location however suggests another possibility, which though vastly different in some ways, is almost identical in others.
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on February 9, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a good example of the typically rough region inside the southern cratered highlands of Mars.

Note the ripple dunes that fill the low areas. The volcanic ash from Mars’ past volcanic history has become trapped here, with those ripple dunes suggesting the direction of the prevailing winds to the southeast.

The bright areas also suggest there is interesting mineralogy just below the surface. The 100-foot-high mesa near the picture’s top suggests a lot of erosion has occurred here, with its top suggesting the elevation of the surface a long time ago.

The most interesting feature however is the meandering ridge that starts at the lower right and weaves to the upper left.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 16, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled it simple as a “terrain sample,” which usually indicates a picture not taken as part of any specific request or research project, but to fill a gap in the photography schedule in order to maintain the camera’s proper temperature.

When such pictures are necessary, the camera team tries to target the most interesting features that will be below MRO during the required time period. In this case they aimed for a north-facing slope, about 340 feet high, made up of a series of terraced layers, distinguished by the sharply contrasting bright flat benches and very dark cliff-faces.

While the cliffs are dark partly because of the sun is coming from the west, putting them in shadow, it is not entirely the cause. Note how the cliffs on the west side of the mound are also dark, suggesting that the darkness is a fundamental feature of the ground itself.
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Today’s cool image takes us to another place on Mars where future colonizers will find the hiking breath-taking. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The camera team labeled it merely as a “terrain sample,” indicating it was not taken as part of any specific research project request, but to fill a gap in the schedule in order to maintain the camera’s proper temperature. When the MRO team does this, they try to pick interesting sites, sometimes successfully, sometimes not.

In this case the image captured the sharp nose of a 2,100-foot-high mesa which to my eye immedately said, “I want to hike a trail that switchbacks up that nose!” Ideally, the trail would then skirt the edge of the mesa, then head up to the top of that small knoll on the plateau. Though only another 200 feet higher or so, the peak would provide an amazing 360 degree view of the surrounding terrrain.
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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on May 14, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “layered butte inside small crater.”

The crater is only about 1.8 miles across, and is only a couple of hundred feet deep, at the most. Because this crater sits on a large slope rising to the southwest, the mesa’s peak is actually about thirty feet higher than the crater’s northern rim, but is still below the southern rim by about 70 feet.

A close look at the mesa’s slopes suggests about a dozen obvious layers, though based on data from the rovers Curiosity and Perseverance, those obvious layers are probably divided into many hundreds of thinner layers in between.

What caused these layers? And how did such a small crater get such a relatively large mesa in its center? As always, the overview map provides some clues, but as always it does not provide a definitive answer.
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