Tag: geology

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) by the camera team not as part of any particular research project but in order to fill a gap in the camera’s schedule so as to maintain its proper temperature. In such cases the camera team tries to pick potentially interesting spots.

This cliff, about 1,100 feet high, is the north wall of a major volcano channel flowing across the Tharsis Bulge, the lava plains that surround Mars’ giant volcanoes. Located in the dry equatorial regions, there is no near surface ice here, but a lot of dust, much of it likely volcanic ash. In the full picture are several ancient craters, all of which are almost entirely buried by this dust and ash.

The cliff wall itself is made up of numerous layers, each representing a past volcanic flood lava event that covered this region with a new flow of material. These events occurred over more than a billion years.
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on February 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “dipping layers”, referring specifically to the mesas with the terraces on their western flanks.

The layers obviously signify past cycles of geological events on Mars. That the terraces are only on one side of the mesas suggests that they are tilted, with the downhill grade to the east.

These layers however pose several mysteries. First, why are they located so specifically in only certain places of this region? It appears that the layered terrain is only found in the lower hollows and valleys. Why?

Second, why are they tilted at all?
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on January 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an area where the ground suddenly transitions from a crazy quilt of criss-crossing hollows and ridgelines to a very flat and smooth plain.

The location is at 21 degrees south latitude, so this is in the dry equatorial regions. Though it has a small resemblance to the chaos terrain that is found in many places on Mars, mostly in the mid-latitudes where glaciers are found, the scale here is too small and the ridges and canyons are not as sharply drawn. While chaos terrain usually forms sharply defined large flat-topped mesas with steep cliffs, here the ridges are small and the slopes to the peaked tops are somewhat gentle.
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Because Mars Reconnaissance Orbiter’s (MRO) CRISM instrument needed to be cooled to low temperatures to use infrared wavelengths for detecting underground minerals and ice on Mars, and the cryocoolers have run out of coolant, the science team has shut the instrument down.

In order to study infrared light, which is radiated by warm objects and is invisible to the human eye, CRISM relied on cryocoolers to isolate one of its spectrometers from the warmth of the spacecraft. Three cryocoolers were used in succession, and the last completed its lifecycle in 2017.

All the remaining instruments on MRO, including its two cameras, continue to operate nominally.

In its final task, CRISM produced a global map showing water related minerals on Mars, released last year, and a global map showing iron deposits, to be released later this year.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on March 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and was taken not as part of any specific research request but by the MRO science team to fill a gap in its schedule while also maintaining the camera’s temperature. Sometimes these somewhat random times show nothing of interest. Sometimes they are fascinating, as in this case.

The photo shows what appear to be a spray of small impacts on an easily melted surface. Imagine spraying hot molten lava on a sheet of ice. Instead of creating a crater with an upraised rim, on impact each droplet would quickly melt a hole.

Did these small impacts all occur at the same time? My guess is yes, based on the overview map below.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

At first glance I thought I was looking at a variety of eroding glacial flows. I was completely wrong. This terrain is located on the floor of 900-mile-long Ares Vallis, thought to have been carved eons ago by some flow, either liquid catastrophic floods or glacial ice, but is now located in the very dry equatorial regions of Mars.

Then what caused these meandering ridges? The overview map below, plus the wider view of MRO’s context camera, provides us more data but little illumination. In fact, both leave us more questions and mysteries.
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From Argyre Basin to Hellas Basin is about 7,000 miles.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 25, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists labeled this image “Crater fill”, but that hardly suffices. First, the fill appears at first glance to resemble peeling paint. At closer inspection, rather than peeling paint we have instead a collection of ridges vaguely resembling cave rimstone dams that either enclose a blob-shaped region or simply meander about until they reach the crater’s interior rim.

The crater interior itself appears largely filled with material so that its rims are subdued. The location, as indicated by that black dot near the center of the overview map above, marks the location at 49 degrees south latitude, in the middle of the cratered southern highlands of Mars where many craters have strangely eroded interiors.

What makes this crater however more puzzling is that none of the surrounding nearby craters look like this. A context camera image taken March 23, 2019 shows that while some of the nearby craters have what appears to be glacial material in their interiors, none exhibit these meandering ridges. This crater stands unique, for reasons that are utterly unknown.

Are these ridges a manifestation of the glacial material filling the crater? Or are they bedrock sticking up through that glacial debris? Your guess is as good as mine.

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Today’s cool image to me illustrates how the presence of near surface ice in the high latitudes of the northern lowland plains of Mars helps to produce a very strange and alien terrain.

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 a typical example of what the scientists have dubbed a “pedestal crater,” where the crater ends up higher than the surrounding terrain because the impact had packed the ground and made it more resistant to erosion.

This theory however does not explain entirely what we see here. That apron mesa surrounding the crater also resembles the kind of splash field that is created when an impact occurs in less dense ice-rich ground. Note too the soft stippled nature of the ground. Wind erosion is not the sole cause of change here.
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Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on January 21, 2023 by the high resolution camera of Mars Reconnaissance Orbiter (MRO). It shows what the scientists label a “pyramidal mound”, which is I think understating the point somewhat.

This pyramid is almost perfectly square, with two perpendicular ridgelines rising from its corners to meet perfectly at the pyramid’s peak. A similar pyramid mound in the Cydonia region, where the so-called “Face on Mars” was found, caused endless absurd speculations in the 1990s of past Martian civilizations, all of which burst into nothingness when good high resolution images were finally obtained in the 2000s.

But what caused this very symmetrical natural feature?
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have labeled simply as a “triple crater,” a very apt description.

What caused this? The most obvious explanation is the arrival almost simultaneously of three pieces. As this asteroid or comet entered the thin Martian atmosphere as a single object, that atmosphere was thick enough to break it into three parts but not enough to destroy it entirely. When it hit the ground, the top piece hit first, with the center and bottom pieces following in sequence, thus partly obscuring the previous hits.

The smaller surrounding craters could either be additional pieces from the bolide, or secondary impacts from ejecta thrown out at impact.
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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on January 15, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The picture was simply labeled “Channel-like feature”, which hardly describes this strange terrain.

Apparently a mantle of surface material has covered and filled an ancient east-west channel. That surface material however has since cracked along the edges of that channel as well along its length. The cracks suggest that the material in the channel is moving downhill slowly, cracking along the cliff walls while also being pulled apart to form the north-south cracks.

My regular readers will I think be able to guess what is going on here, but if you can’t, the overview map below will help explain this.
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Today is the last part in our four part exploration of the cratered southern highlands of Mars, begun last week. (For the early parts, go here-Part #1, here-Part #2, and here-Part #3.) Though there is no need, new readers should read the first three parts first, in order to get the larger perspective of this final post.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on December 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the eastern main gully descending down into a pit that sits in the north center of 52-mile-wide Asimov Crater, as shown in the inset on the overview map above. (For an MRO high resolution of the western gullies into this pit, see this January 2019 cool image post.)
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This is the third part of this week’s series taking a look at some of the strange features in the southern cratered highlands of Mars. In the first part I posted a beautiful image of what appears to be a crater filled to the brim with glacial ice, surrounded by an ice sheet plain. In part two we took a look at the interior of Rabe Crater, which though very nearby does not appear to have obvious glacial features within it at all. What it has instead are deep open air pits and a lot of sand dunes.

Today’s image to the right, cropped, reduced, and sharpened to post here, takes us to the interior of an unnamed 45-mile-wide crater only about 70 miles north of Rabe. The black dot in the inset on overview map above indicates the photo’s location. The picture was taken on January 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Like Rabe, this crater also has many large open-air pits. In the picture one pit, near the lower center of the picture, is surrounded by soft-looking mounds and a strangely swirling textured and uneven terrain that makes up the majority of the crater’s floor.

This picture might help explain what we saw in Rabe. The textured terrain in this unnamed crater could easily be ice-impregnated and now hardened sand dunes. The pit could be where that impregnated ice has sublimated away, leaving behind the dust from those ancient dunes which then forms new sand dunes. In Rabe, the crater floor above its pits looks very similar to this swirling textured surface, suggesting the same process is going on there.

What strengthens this explanation is the many other craters nearby, all indicated by red dots in the overview map above, that also have pits or distorted crater floors. Their proximity suggests that there is an underground ice layer in this region, always at about the same elevation, and each crater impact exposed it. With time that exposed ice, no longer pure but filled with material from the impacts, sublimated partly away, producing the pits as well as ample sand to form sand dunes.

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Today and for the next three days the cool images that I will post from Mars will explore a region that I have not covered very much in depth, the cratered southern highlands between the giant basins Argyre and Hellas. The map above is an overview of this 7,000-mile-long region, all of which is inside the 30 to 60 degree south latitude band where scientists have found much evidence of buried glaciers. In this region the bulk of that evidence is most obvious inside craters.

The picture to the right, cropped, reduced, and sharpened to post here, was taken on December 21, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a typical example of the kind of glacial feature found. The white cross on the map marks its location, west of the Hellespontus Mountains that form the western rim of Hellas Basin.

Scientists have dubbed this feature concentric crater fill, a purposely vague term because — though it looks like glacial fill — until there is data to confirm it the scientists would quite properly rather not commit themselves. The concentric rings suggest multiple layers, each of which likely marks a different climate cycle in Mars’ geological history.

In this case the glacier features also appear to cover the entire plain surrounding the crater as well as its rim. The small crater to the west is similar, and both give the appearance that the ice sheet that covers them came after the impact, draping itself over everything, with the craters only visible because the ice sheet sags within their interiors.

More crazy features from the cratered highlands to come.