Tag: geology

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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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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The white dot on the overview map above marks the location, on the west end of the 2,000-mile-long northern mid-latitude strip I label glacier country because almost every image suggests the presence of ice and glaciers.

Where this crater is located the terrain is shifting from mesas and criss-crossing canyons to the northern lowland plains. Thus, the features that suggest the presence of ice shift from glacial in nature (flowing down hollows and cliffsides or within canyons) to that of a near-surface ice sheet, which acts to distort impact craters and leave large splash aprons around them.

The straight depression cutting into the crater near the center top that is also aligned with craters to the southwest suggests that these craters are either sinkholes into a void created by a fault line, or the impacts all occurred at the same time, as the asteroid broke up while cutting through the Martian atmosphere.

Either could be true. The data is insufficient to determine which.

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Today’s cool image not only shows us some puzzling lava terrain on Mars, it highlights the continuing camera problems on Mars Reconnaissance Orbiter (MRO) that began last month and now appear to be permanent.

The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 29, 2023 by the high resolution camera on MRO. The black strip through the middle of the picture highlights MRO’s ongoing problem, as described by the science team in its monthly download of new MRO high resolution pictures:

The electronics unit for CCD RED4 started to fail in August 2023 and we have not been acquiring images [data] in this central swath of the images. The processing pipelines will be updated to fill this gap with the IR10 data for some products. The 3-color coverage is now reduced in width.

The picture shows the failure of this electronics unit. The color strip is now only about half as wide as normal, with the other half the black strip with no data. As the problem first appeared in July, and remains unresolved, it probably is permanent. Though MRO’s high resolution camera can still produce images, they will be less useful, their center strip blank.

This failure should not be a surprise. In fact, it is remarkable that so little has gone wrong with MRO considering its age. The spacecraft was launched in 2005, entered Mars orbit in 2006, and has been working non-stop now for about seventeen years. Moreover, it was built in the early 2000s, making it almost a quarter century old at this point. How much longer it can survive is an open question, but a lifespan of twenty years is usually the limit for most spacecraft. The Hubble Space Telescope however gives us hope MRO can last longer, as Hubble has now been in orbit for 33 years, and continues to operate.

Despite this data loss, the picture still shows some intriguing and puzzling geology
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The white spot near the center of the overview map above marks its location, deep inside the 2,000-mile-long region in the northern mid-latitudes I call glacier country, as everything there seems covered with glacial features of some kind. All the features in this picture are smaller than 50 feet high, based on the resolution of the topographical data obtained by Mars Global Surveyor in the 1990s.

What makes this picture interesting are the layers, made most obvious in the terraced mesa in the upper left. Surrounding this mesa for dozens of miles in all directions are similar layered features, all suggesting that the glacial ice sheets that appear to coat this region have either have been sublimating away over time, or when growing grew less with each subsequent growth cycle.

Though both have or are likely happening, the latter most likely explains the terraces, as there is a lot of evidence on the surface of Mars showing that each subsequent growth cycle produced smaller glaciers and ice layers.

From the perspective of future colonists, this picture once again shows that water will readily accessible on Mars, as long as you travel north or south of the equator at least 30 degrees of latitude. This location is at 42 degrees north, and is very typical of this whole region.