Tag: geology

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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 8, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the top half of the northwestern interior wall of the central caldera of Pavonis Mons, the center volcano in the string of three giant volcanos found in Mars’ equatorial regions.

The elevation change from the top to the bottom of this picture is about 7,000 feet, though this covers only half the distance down to the floor of the caldera. The picture was taken as part of a survey of this caldera wall.

Volcanic activity here is thought to have ended more than a billion years ago. Thus we are looking at relatively old terrain that has had many eons to be reshaped since the last eruption.
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also inserted data from a July 28, 2008 context camera image into the blank strip that now exists in the center of high resolution camera images due to the failure of one sensor.

This photo is what the camera team calls a terrain sample, and was probably 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. When the camera team does this they try to find locations that either have not been observed in much detail previously or have interesting features. In this case the team accomplished both. The interesting features are the two pedestal craters, both surrounded by splash aprons. Neither has been observed in high resolution previously, and the context camera has only taken two pictures of this location in total.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 21, 2023 by the high resolution camera on Mars Reconnaissence Orbiter (MRO). Its focus is the meandering ridge in the center of the picture, which the scientists intentially describe vaguely as a “ridged flow-like feature”.

The elevation difference between the high and low points within the picture is about 500 feet, though most of that slope occurs in the lighter terrain on the right. The darker area where the ridge is located has no clear elevation trend, though there are hints of depressions and rises within it.

The yellow dot on the overview map above marks this location, deep within the chaos terrain dubbed Deuteronilus Mensae, on the western end of the 2,000 long northern mid-latitude strip I dub glacier country, because practially every image from there shows glacial features.

To underline this fact, the red and white dots mark previous cool images from 2020 and 2021, with the first showing an eroded glacier and the second glacial ice sheets.

The mesa to the east of this picture rises more than 6,000 feet to its peak, as indicated by the black dot. This is also the highest point for this entire grouping of mesas. All are surrounded by a single large apron of material, likely a mixture of alluvial fill and ice.

What however caused the narrow ridge in the picture above? Is it ice or bedrock? If ice why is it so different than the glacial material that seems to surround it? If bedrock, it suggests it is instead an ancient inverted channel created when that ridge was a canyon through which ice or water flowed, compacting the canyon floor. When the terrain around it eroded away it was more resistent and became a ridge instead.

I have no answer. The colors suggest the ridge is rock, not ice, but that is not conclusive.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a lava flow that cut through an older 2-mile-wide crater, mostly burying it as it burst through the crater’s southwest and northeast rims. From the caption:

A lava channel extends from the feature and continues 60 kilometers to the northeast, growing deeper along its path. The circular formation is likely an eroded impact crater whose walls have been breached by the lava as it surrounded the rim and then infilled the crater. Alternatively, it could represent the location of a volcanic vent that sourced some of the lavas that formed the channel.

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Today’s cool image is a perfect example of why nothing in science research should ever be taken at face value, without digging a bit deeper. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

First an important technical point. Though the electronics unit for one of the camera’s color filters is still not working — causing a blank strip down the center of all black & white images, the camera team has gotten around this problem by inserting in that strip other color filter data, thus creating a complete image as you see to the right. This work-around means that MRO’s capabilities, though showing signs of age, will continue almost as good as before.

As for the image itself, when I first looked at it, I was baffled by the striking contrast between the mottled and rough ground in the lower left, and the almost featureless and smooth terrain everywhere else. Why this sudden transition? What could cause it? That inexplicable contrast demanded I post it as a cool image.
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Cool image time (necessary when there is no real space news to report)! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 29, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “steep crater walls.”

And the interior slopes of this 5-mile-wide unnamed crater are steep, about 600 feet high and descending at a grade of 10 to 13 degrees, getting steeper as you go down. In fact, the floor of the crater itself continues that slope downward to the west until it reaches the base of its western interior wall. For some reason the glacial material within it is piled up higher on its eastern end.

The dark streaks on the crater interior walls are either slope streaks or recurring slope lineae, with the former appearing somewhat randomly and the latter seasonal in nature. Both remain unexplained unique phenomenons of Mars. This new picture was likely a follow-up of a January 2014 MRO picture to see if anything had changed in the past decade.

To my eye it is difficult to detect any changes, but I am not looking at the highest resolution version of the picture. The lack of changes suggests the streaks are seasonal lineae, as both images were taken in the northern spring and the streaks in both appear much the same.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 16, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team describes this as “clusters of scour pits,” which means the pits here were formed by the prevailing winds, which according to a global analysis of dunes on Mars, is probably blowing from the west to the east at this location.

This image only covers a small section of these scour pits. The full field extends about 20 by 18 miles across, and appears to be the southeastern flank of a mile-high dome. The scour marks could therefore also be evidence of some sagging of this material downhill along that flank.

It is also possible that the flow of the prevailing winds across this southeastern downhill slope is causing the pit formation. Unlike this flank, the rest of this dome is relatively smooth.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a steep 1,000-foot-high cliff with what appears to be extensive glacial material at its base.

The many layers all suggest past climate cycles, where snow was deposited and the glacier grew, followed by a period when no snow fell and the glacier either shrank or remained unchanged. The terraced nature of the layers near the base of the cliff suggest that with each active cycle less snow was deposited and the glacier grew less.

The latitude is 33 degrees south, which puts it just outside the dry equatorial regions of Mars and inside the mid-latitude region where many such glacial features are found. Its closeness to the tropics however is significant, because by this point we should be seeing a diminishment of such features. Instead, the wider view shows us that the near surface ice in this region is extensive and in fact appears to cover everything.
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The central darker strip however comes from a September 27, 2008 image by MRO’s lower resolution context camera, inserted to fill in the blank section where one component on the high resolution camera has failed.

The picture focuses on what the scientists call a “pit interacting with a mound.” The 100-foot-deep pit is one of a very long meandering string of such pits, all of which suggest the existence of an buried river canyon into which debris is sinking. Altogether this particular string runs from several dozen miles, and its interaction with the triangular 300-foot-high mound suggests at first glance that the river that created the canyon did a turn to the left to avoid a large underground mountain, now mostly buried but revealed by its still exposed peak.

As is usual in planetary research, the first glance is often wrong. The overview map below provides a different answer, which says the formation of the aligned pits is related to the formation of the mound itself.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team calls the features here “narrow ridges”, but what makes these criss-crossing ridges interesting is their location within the picture.

They appear only inside the hollows and depressions, as if erosion had stripped out a top layer of softer material to reveal these ridges, made of a harder material. The almost random but straight orientations of the ridges also suggest they formed along faults or cracks, which also suggests we are seeing dikes where lava was pushed up from below.

Whether the eroded softer material is lava or volcanic ash is unclear, though it certainly resembles the ash layers seen in the giant Medusa Fossae Formation ash field on the opposite side of Mars.

As always, a wider look helps clarify things.
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Scientists mapping the location of mud volcanoes in chaos terrain in the dry equatorial regions of Mars have found numerous mud volcanoes, adding weight to the theory that an intermittent shallow lake once existed there.

The inset on the overview map to the right indicates the location of those mud volcanoes (of two types) in white and orange dots. What is significant is that none of the volcanoes are found on the mesas within this chaos terrain, only in the low flats below. From the caption:

Both feature types result from sedimentary volcanism – instead of magma upwells and eruptions, wet sediments, and salts reach and breach the surface, forming mounds and flows. Interestingly, these mounds only occur over the chaotic terrain floor materials and not on the mesas (red-shaded areas) they embay. This suggests a material composition link rather than a genesis by regional extensional forces generated by magmatic rises.

The blue areas are where this same science team think an intermittent inland sea once existed. This new data reinforces that hypothesis.

Features that look like mud volcanoes are common in the icy northern lowland plains. Finding them in the dry equatorial regions strengthens the theory that water was once common there. For this reason the scientists are proposing a mission to this location, especially because the possibility of water might increase the chances of discovering past life.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label “branching deposits,” two wiggling ridgelines with other ridges branching off from them.

What caused this? On Mars there are many such meandering ridges, all of which look like rivers that have positive relief, the opposite of what you would expect. The theory is that these weaving ridges were once canyons where either water or ice once flowed, compacting the streambed so that it was more dense than the surrounding terrain. When that terrain eroded away it left that streambed behind, as a raised meandering ridge.

That answer however might not apply here.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

In this one picture can be seen a glimpse of the entire history of the numerous lava eruptions that once dominated Mars when its giant volcanoes were active one to three billion years ago. The three aligned craterlike depressions likely signal the existence of a large lava tube below ground, placed there during an early large eruption, when the volcano was spewing out so much flood lava that such large tubes could form. The smaller meandering surface rills signal later eruptions that carried less flood lava and thus produced a smaller drainage features.

And finally, the rough and cracked appearance of the surface indicates the ancient age of those last eruptions, probably laid down about a billion years ago. Since then, the volcano has been dormant, and the frozen lava here has had time to erode, become roughened, and show signs of slowly wearing away.
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Cool image time! It is always dangerous to come to any quick conclusions about what you see from pictures from another planet. The photograph to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what at first glance looks like a surface similar to frosting seen on window panes on Earth in the winter, where water condensation freezes to form crystalline patterns.

Your first glance would be wrong. This terrain is about 120 miles north of the Martian equator, placing inside the dry equatorial regions where no near-surface ice is known to exist. If this geological feature is formed by the same condensation processes that create ice frost, then it must involve the deposition of some other type of material.

The explanation would also have to account for the change in the terrain, from finely patterned on the right to more crystalline on the left.
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