Tag: MRO

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Cool image time! The photo above, rotated, cropped, and reduced to post here, was taken on March 5, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “viscous flow feature,” which is another way of saying the flow was thick and syrupy.

Nor is such a flow unusual in this area of Mars. It is located in a region of chaos terrain dubbed Protonilus Mensae, which is also the central mensae region in the 2,000-mile-long strip in the northern mid-latitudes of Mars I label glacier country. The overview map above of Protonilus Mensae — covering about 500 miles in width — shows how common such flows are in this place. The black rectangles mark the locations of other cool images I have featured, as follows:

• 1. Buried glaciers flowing off of Martian mesa
• 2. Brain Terrain on Mars
• 3. How to spot a glacier on Mars
• 4. Glacier country on Mars
• 5. Revisiting Mars’ glacier country
• 6. Back to Mars’ glacier country
• 7. A cracking Martian glacier?
• 8. Ice-filled craters in Mars’ glacier country?

The red rectangle indicates the location of today’s cool image.

The glacial aspect of everything in this region is even more emphasized by the wider view provided by MRO’s context camera below.
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on November 22, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labeled a sinuous ridge. Make sure you also look at the full image. The ridge goes on to the south, but then fades way as an almost perfect ramp, only to have another even more wiggly but thinner north-south ridge begin only a few feet to the west.

Sinuous ridges like this are found in many places on Mars. Almost always their origin is thought the result of a former river channel that became a ridge when the surrounding softer material eroded away.

That explanation however does not seem to work for this ridge. It has too many other inexplicable features. For example, note how the peak of the ridge smoothly transitions from sharp to flat-topped. It has a soft appearance that is strengthened by the gap near the top.

It is almost as if this ridge is a kind of elongated sand dune! And guess what: The overview map below gives that explanation some believability.
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In our third Martian cool image of the day, we go to the north pole of Mars, as seen from orbit by the high resolution camera of Mars Reconnaissance Orbiter (MRO). Taken on March 30, 2022 and cropped and reduced to post here, this picture shows some of the distinct and unique geological features found only on the polar caps of Mars. From the caption by Candy Hansen of the Planetary Science Institute in Tucson, Arizona:

Both water and dry ice have a major role in sculpting Mars’ surface at high latitudes. Water ice frozen in the soil splits the ground into polygons. Erosion of the channels forming the boundaries of the polygons by dry ice sublimating in the spring adds plenty of twists and turns to them.

Spring activity is visible as the layer of translucent dry ice coating the surface develops vents that allow gas to escape. The gas carries along fine particles of material from the surface further eroding the channels. The particles drop to the surface in dark fan-shaped deposits. Sometimes the dark particles sink into the dry ice, leaving bright marks where the fans were originally deposited. Often the vent closes, then opens again, so we see two or more fans originating from the same spot but oriented in different directions as the wind changes.

The top layer of translucent dry ice falls as dry ice snow during the winter, than sublimates away with the arrival of spring. Since this photo was taken in autumn, we are looking at features left over from the activity from the spring and summer.

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Cool image time! The photo to the right, cropped to post here, was taken on February 27, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a nice collection of what scientists have informally (but permanently) labeled as spiders, strange formations that exists only in the regions of the Martian south pole.

The spiders are believed to have formed because of the coming and going of the dry ice mantle in the polar regions that falls as snow in the winter and then sublimates away come the spring. Because dry ice is mostly clear, the spring sunlight penetrates it and warms the underlying surface, which acts to warm the base of the dry ice mantle. CO2 gas builds up, trapped below the dry ice, until the pressure causes it to break the dry ice at a weak point and spew outward, carrying with it dust that blackens the surface above. You can see three examples in today’s image.

Spiders however only happen at the south pole. In the north much of the terrain is formed by unstable dunes, which change from year to year, thus causing the gas breakage to occur at random and different spots.

In the south however the terrain is more stable, a surface of ice and dirt. The spiders form because the trapped gas always follows the same path from year to year to the same weak points, carving riverlike tributaries until these feeders combine and build up enough gas pressure to crack the overlying dry ice so that the gas can escape.

Though the gas functions much like a river of water, it has one fundamental difference that makes this phenomenon wholly Martian and quite alien. On Earth rivers flow downhill. On Mars, the gas in these spider tributaries is flowing upward, seeking a path into the atmosphere above.

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Cool image time and a mystery! The photo to the right, cropped to post here, was taken on March 29, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) of an 18-mile-wide crater in the southern cratered highlands of Mars. The full picture, dubbed “Steep Cliff,” was taken apparently to get a good view of the crater’s northern rim. The rim’s steepness suggests that the floor of the crater is significantly filled.

More intriguing however are the scattering of strange depressions about six miles south of the rim. What caused them? The crater’s location is in a part of Mars where it is not unusual to find both glacial features as well as flood plain lava. In fact, the crater’s northeast and southwest rims appear to have been buried by what appears to be flood lava. The northern rim’s shallowness also suggests the crater is well filled with flood lava.

However, the crater is also at 38 degrees south latitude, a latitude where planetary scientists have found lots of glacial features. Much of this crater fill could be glacial.

The overview map below illustrates this mystery.
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Cool image time! The picture to the right, rotated, cropped, reduced, and annotated to post here, was taken on September 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows what appear to be a variety of flows, from alluvial fill to slope streaks to dust coming down the southeastern interior rim of 77-mile-wide Orson Welles Crater on Mars.

The location is almost right on the equator, so none of these flows are ice- or water-related. Nor are such flows unusual in the meandering 800-mile-long canyon that cuts through Orson Wells crater, dubbed Shalbatana Vallis. I featured similar flows at a spot to the north and downstream from this one in May 2021, also on the canyon’s eastern rim.

The overview map below provides some context.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a cliff escarpment that, based on a rough estimate of MRO’s elevation data, ranges from 10,000 to 13,000 feet high. Because the sun is only about 32 degrees above the western horizon, the shadows are long and distinct and bring out the features quite dramatically.

On Earth, a mountain 13,000 feet high would generally be named, because there are really not that many of them. If it was a cliff face dropping down into a canyon, which this Martian cliff is, it would be quite unique and probably be one of the most popular tourist spots on the globe. For comparison, the rim of the Grand Canyon in the national park, visited by millions, is only 4,000 to 6000 feet in elevation. This cliff on Mars is more than twice as deep, and yet, it is hardly the most spectacular canyon rim on the red planet.

The overview map below explains this.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 10, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It shows what planetary scientists have dubbed “brain terrain”, a truly unique Martian geological feature that is not found on Earth and also remains as yet unexplained. Specifically, the brain terrain is the speckled areas between the larger flow features, all of which are probably ice or glacier related.

What especially drew me to this MRO image however was the particular flow feature in the center left that looks like either a giant squid or something out of Lovecraft horror short story. Talk about a cool image!

The downward grade here is likely to the north, as this spot is inside a north-south canyon, cutting into the southern cratered highlands. The general north-south trend of the depression here reinforce this supposition.

The overview image below provides context.
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Yesterday’s Picture of the Day from the high resolution camera on Mars Reconnaissance Orbiter (MRO) revisited a captioned image first posted in February 2014 by the science team. That picture, cropped and enhanced, is to the right. From the 2014 caption:

There is a large channel system that flows into the basin, called Ladon Valles, and scientists think that the basin may have once filled with water before another channel to the north formed and drained it. These exposures of light-toned layered sediments provide clues about the environment that existed within Ladon Basin when water may have ponded and deposited these sediments.

Later research has generally concluded that these white sediments are iron and magnesium smectites, often appearing as white tuff material whose deposition is generally associated with precipitation of water or snow and its subsequent evaporation or sublimation.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be at first glance a relatively featureless plain with a lighter material covered by a patchwork of darker material.

Note however the lack of craters. Except for several faint depressions near the image’s center, there are none. And those depressions look like the expression of craters that have been covered by material. Is the two-toned surface here an expression of past lava flows? Or are we seeing an ice-sheeted plain, with the patches representing higher terrain above that plain?

The overview map below answers the question somewhat clearly.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 18, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “degraded crater in Utopia Planitia.”

There is a lot of intriguing geology in this one image. First of course is the crater itself. We have to ask, is it from an impact or from some volcanic process? The location, at 44 degrees north latitude, argues that some form of ice or mud process was involved. Maybe we are looking at a frozen eruption from an underground ice layer. If this was instead caused by an impact, the crater’s ringlike structure could have been created by the ripples of melted ice and mud emanating away but then quickly refreezing.

Surrounding the crater are many small fissures, the largest ones all oriented in a north-south direction. If there is an ice layer near the surface, these cracks might be caused by that ice sublimating away. Why the largest cracks orient in the same direction however is a mystery.

The color variations suggest [pdf] dust (red-orange) as well as a variety of minerals (green). Since no blue appears visible in this version of the photo, if this crater was shaped by melting or erupting ice, that ice is well covered by that layer of dust and debris.

The location map below as always provides context.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on November 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a collection of scattered thin surface fractures, grouped in clusters of parallel lines with the orientation of the clusters all somewhat random to other clusters.

The fractures, as well as the material inside the craters, appears to resemble glacial features, suggesting that these fractures are the result of either the past motion of the glacial sheet, or the sublimation of the buried ice, which causes it to crack and shrink as it slowly dissipates away.

The problem with that hypothesis is the location, as shown by the overview map below.
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For full images go here and here.

Cool image time! Today the science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) released images showing a very recent avalanche, or slumping, on the interior slopes of what looks like a small three-mile-wide crater inside the easternmost reaches of the giant canyon Valles Marineris.

The comparison above, reduced and rotated to post here, is their close-up showing the change, which occurred sometime between March 2021 and February 2022. The wider comparison on the right, cropped, reduced, and annotated by me, shows a wider view to help place this slumping in the context of the crater.

Calling this an avalanche is not really accurate, as it isn’t really the fall of boulders and rocks, but the quick slumping downward of an entire section of what looks like dust or sand. As Alfred McEwen of the Lunar & Planetary Laboratory in Arizona writes in the caption:
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a mesa sticking up on the relatively flat and featureless northern lowland plains in Utopia Planitia, the second largest impact basin on Mars.

The full image shows three such mesas. Though pictures taken in the northern lowlands of Utopia tend to show evidence of buried ice or glaciers, the impression I get from this picture is one of dryness. If there is any ice here, it is below ground. And even that seems unlikely. The surface surrounding nearby craters does not have that squishy and slushy look that is seen in the north when an impact occurred on near surface ice. Instead, the ground looks solid.

The overview map below reinforces this impression.
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Cool image time! Among the many strange and unexplained geological features that scientists have identified on Mars, the thumbprint feature is one of the most intriguing. The photo to the right, cropped and reduced to post here, is a fine example, and was taken on September 10, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The thumbprints are the lighter splotches, and are generally found near curved ridges located mostly in Martian lowlands. All appear to have crater-like features in them, though these craters are not impact craters, but likely (though not confirmed) caused by some form of underground eruption, be it mud, ice, lava or something else. Though scientists do not yet really understand the process that formed the thumbprints, the data strongly suggests that they formed in connection with glacial events. From this 2003 paper [pdf]:

TT [thumbprint terrain] as well as the associated trough systems were formed by a glacial mechanism. [Elevation] data show that the trough systems consistently lie topographically above the TT; this implies that if they were they formed by the same glacier, the troughs must have formed before the glacier retreated and formed the TT.

The splash apron around the crater near the bottom of the photo supports the glacial theory, implying the presence here of underground ice.

Scientists have also theorized wind processes and cinder cones as explanations for these features.

These particular thumbprints are located, as shown in the overview map below, in the same general area as a previous cool image of thumbprints, from April 2019.
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Today’s cool image, which at first glance does not seem so puzzling, actually falls into my “What the heck?” category of baffling Martian geology. The picture to the right, cropped and reduced to post here, was taken on January 15, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled “Avernus Cavi fractures”, it shows what resembles the well-documented chaos terrain seen in many places on Mars, where erosion over eons along fault lines creates mesas with random criss-crossing canyons.

The problem is that this location is practically on the Martian equator, and chaos terrain tends to be found in the mid-latitude bands where there are many glaciers, suggesting the cyclical waxing and waning of those glaciers is what causes the erosion. Here at the Martian equator the terrain is very dry. No glaciers.

Moreover, note the higher mesa near the top center. Its flat top suggests that once this terrain was covered with an even higher layer of material, almost all of which was stripped away evenly everywhere, except where that mesa sits. As an amateur geologist I can’t think of any sequence of events that would do such a thing. I suspect professionals might have problems themselves.

Then there are the small parallel ridges. They suggest dunes, especially inside the depressions where sand and dust can get trapped. On the mesa tops however these ridges are more mysterious. Why for example are they aligned with the small ridge in some hollows, but not others? They in many ways remind me of the ridges in this earlier “What the heck?” cool image, also right on the equator.

The overview map below provides some help, though not much.
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on January 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter. It shows what the science team labels a “modified crater.”

What I see is an old crater almost completely covered by glacial material. That material however is also very old, as there are numerous small craters on its surface, enough that it must have been here for a long time. Its cracked surface also suggests this glacier is very old.

Thus, while we might have ice here, buried by a thin layer of dust and debris to prevent it from sublimating away, it must be very old ice. The many climate cycles caused by the extreme swings in Mars’ rotational tilt, from 11 to 60 degrees, have apparently not caused this ice to ebb and flow very much.

Might it therefore not be ice, but hardened lava?

The location, as shown by the overview map below, provides some context, but only makes this mystery more puzzling.
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