Tag: geology

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

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.
» Read more

Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on April 5, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have cropped it to focus on the geological feature that likely attracted the interest of the scientists who requested this photo, the mesa that has a ridgeline running over it as if the mesa was not even there.

The mesa is about 80 feet high on its west side, but on its east the ground continues to drop away more than 500 feet as you move 2.5 miles to the east. Based on how the MRO science team interprets the colors [pdf] in the color strip, the orange areas are likely dust while the greenish surface suggests coarser sand and boulders. This conclusion is reinforced if you look at the parallel dunes south of the mesa. The dunes are yellow-orange (dust) while the ground between is yellow-green (sand), exactly what you expect with the larger coarser material settling in lower elevations.

The overview map provides the context, which might help explain the ridgeline.
» Read more

Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

This is one of what I like to call “What the heck?” images. The broken up blocks resemble ice floes on the edge of the Arctic ice cap that have broken off and have begun floating away.

The problem with this theory is many fold. First, this is on Mars and not on Earth. Second the “sea” these blocks are supposedly “floating” in is actual solid lava. There is no water or ice here, on the surface or even underground. This is in the dry tropics of Mars, where little or no near-surface ice has so far been detected.

The overview map below provides some context, and possibly an explanation.
» Read more

Click for original image.

Cool image time! The picture above, cropped, reduced, and sharpened to post here, was taken on April 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a gully that cuts down from the western rim of a 21-mile-wide unnamed crater in the southern cratered highlands of Mars.

The small rectangle on the overview map to the right marks the location, with the inset providing a close-up of this crater, with the white bar indicating the area covered by the photo above. The overall elevation loss from the rim on the left down to the crater floor on the right is about 3,800 feet.

The first high resolution picture of this gully was taken in 2016, with subsequent pictures taken in 2021 and 2022. In comparing the newest picture above with the 2016 photo I can detect no changes, but I am not looking a the highest resolution available. In addition, both of these pictures were taken during the Martian spring. The 2021 and 2022 pictures were taken during the Martian summer, and in both the north-facing wall where the gully is beginning to narrow seemed brighter.

It is likely the researchers are looking to see if any frost — either ice or dry ice — appeared during the winter and then sublimated away in the summer. Such a change could cause some of the erosion that produced this gully.

For the original images go here and here.

Today’s cool image is actually a comparison of two different high resolution images from Mars Reconnaissance Orbiter (MRO), both of which illustrate why it is very dangerous to come to any conclusions about such images without knowing a lot more about them.

The top image to the right, cropped to post here, was a terrain sample image taken on March 30, 2024. Such images are usually taken not to complete any particular research project, but are taken to fill a gap in the schedule in order to maintain the camera’s proper temperature. When the camera team has to do this, they attempt to pick a spot that might have some geological interest. Sometimes they get something surprising. Often however the features in the picture are boring.

In this case they spotted a place where the ground appears appears to be eroding away in a random pattern.

The bottom image, cropped, reduced, and enhanced to post here, was taken on March 24, 2024 and was part of planned research. It shows a section of the Martian south ice cap, specifically the area where scientists believe there is a residual permanent small cap of dry ice on top of a thick underlying water ice cap.

Like the top image, the features here suggest some sort of erosion process eating away randomly at the ground’s upper layers.

The two images illustrate the difficulty of interpreting orbital images. At first glance the geological features of both appear very similar. Yet the top image is located in the very dry equatorial regions of Mars, and in fact is inside the Medusae Fossae Formation, the largest field of volcanic ash on the red planet. The layers here are likely ash, and the erosion that carved out the hollows likely came from wind. If there ever was near-surface ice at this location, it was many eons ago.

The bottom image however likely shows the sublimation process that is slowly eating away at the residual dry ice cap at the south pole. The Martian north pole does not have residual permanent cap of frozen carbon dioxide, and the reasons why the two caps are different in this way are complex and not completely understood.

Both images show erosion that produces features that look similar. But the materials involved and the causes are completely different.

Remember this when you look at any orbital picture taken of Mars, or any other planetary object. Without the larger context (location, make-up, known history), any guess about the nature of the features there is nothing more than a wild guess, no different than throwing darts at a wall while wearing a blindfold.

Click for original image.

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

It shows what the science team labels a “scour pit island,” an area about 13 miles long and 3.5 miles wide where the ground is covered by these pits.

Your eye may play tricks on you, reversing the elevations. These are all pits, with most having a central peak or ridgeline. To help, note that the sunlight is coming from the west. The arrow on the center left of the picture sits on a plateau above these pits.

According to this paper [pdf], the pits are slowly dug out by the wind coming from the southeast blowing to the northwest, as indicated by the arrows. The central peaks or ridges are thought to be a hint of the original topography, with the wind only able to pull ash from the terrain around these peaks.
» Read more

For original images go here and here.

Today’s two cool images above provide a nice sense of the massive nature of many Martian landslides. Scientists often call this kind of slide “mass wasting,” because rather than it occurring because a single rock propagates a larger flow of rocks as it starts rolling downhill, this slide occurs because a large section of the hillside suddenly breaks free and moves downward as a unit, carving a path as it goes.

Mars has a lot of these kinds of slides, likely caused partly by its lower gravity, 39% that of Earth’s.

The overview map to the right marks the location of both slides by their numbers. Number one took place on the eastern interior rim of a 56-mile-wide and 7,000-foot-deep unnamed crater the dry tropics of Mars. The slide dropped about 3,000 feet, beginning about halfway down from the top of the rim and not quite reaching the crater floor. The picture was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on March 31, 2024.

Number two occurred on the western interior rim of a 32-mile-wide and 6,500-foot-deep unnamed crater in the mid-latitudes where near-surface ice and glacial features are often found. In this case the slide fell downward about 3,500 feet. The picture was taken by MRO’s high resolution camera on March 14, 2024.

Despite the different latitudes and thus different climates and geological settings, both landslides look similar. It is possible they occurred under similar conditions, but at very different times. Or it is also possible that the Mars gravity and general environment promotes these mass wasting events everywhere.