Strange terrain southwest of Jezero Crater

Strange terrain near Jezero Crater

Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 16, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have merely label “landforms.”

I instead call them strange. Clearly we are seeing exposed layering that surrounds the mesa in the middle of the image. This in turn suggests that the mesa top was once the surface of this whole region, and that region had been formed by the repeated placement of multiple sedimentary layers. Then, over time the surrounding terrain was eroded away, exposing those underlying layers.

Even so, some of the parallel lines do not appear to be layers, but striations etched into the ground. To get a better look, the white box marks the area covered by a full resolution close-up below.
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Glacial flows pushing out through a Martian crater rim

Wider view of 6-mile-wide crater
Click for full image.

Today’s cool image once again illustrates how Mars is far from a waterless planet. Instead, there is strong evidence that water ice can be found across most of the Red Planet’s surface, excluding the equatorial regions lower than 30 degrees latitude.

The photo to the right was taken on September 11, 2021 by the wide view context camera on Mars Reconnaissance Orbiter (MRO). It shows a 6-mile-wide unnamed crater on Mars, located at 35 degrees south latitude, with what appears to be a glacier in its interior, flowing to the southwest towards several breaches in the crater’s southwest rim. Several of those breaches now sit higher than the flow, suggesting that the glacier itself was once higher and flowed out of those gaps. Now the level has dropped, and the only place the glacier exits the crater is the central gap at the center of the white rectangle.

That white rectangle marks the area covered by a recent MRO high resolution image, taken on March 29, 2022 and cropped and reduced to post below.
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Ice in the Martian equatorial region?

Global overview of ice on Mars

Glacial features in low latitude Martian crater

Today’s cool image to the right, rotated, cropped, and reduced to post here, is actually an older captioned image, published in 2017 by the science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO). I missed its significance when it was first released. From the caption by Alfred McEwen of the Lunar & Planetary Laboratory in Arizona:

The material on the floor of this crater appears to have flowed like ice, and contains pits that might result from sublimation of subsurface ice. The surface is entirely dust-covered today. There probably was ice here sometime in the past, but could it persist at some depth?

This crater is at latitude 26 degrees north, and near-surface ice at this latitude (rather than further toward one of the poles) could be a valuable resource for future human exploration.

As shown in the global map of Mars above, this 26-mile-wide unnamed crater, marked by the black cross, is well inside the equatorial region 30 degrees north and south from the equator where almost no evidence of near surface ice has been found. Whenever I look at an image from MRO, if the picture appears to show ice or glacial features, its latitude is always 30 degrees or higher. If it does not, it is almost always in this equatorial region.

This crater however shows evidence of glacial features in its interior, but is far closer to the equator than normal. How could this be? It is possible that its high altitude, sitting in the southern cratered highlands, might have helped preserve its buried but near surface glacial features.

Regardless, as McEwen notes, its location closer to the equator is tantalizing, because it suggests that such ice could exist even in the equatorial regions, though buried and thus not detected by the instruments presently available in Mars orbit.

Inverted Martian tadpole

Inverted Martian tadpole
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Cool image time! On Mars it is not unusual to see what scientists call tadpole features, craters with meandering canyons or channels either flowing into or out from the crater’s rim. The photo to the right, rotated, cropped, and reduced to post here, is another example, though with one major difference. The channel and crater are inverted, with the channel instead a ridge and the crater a circular plateau. The picture itself was taken on April 16, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Orbital images have found on Mars a lot of what scientists call pedestal craters, where the impact packed and hardened the ground under the crater so that when the surrounding terrain eroded away the crater remained, as a plateau.

Scientists have also found on Mars a lot of what they call “inverted channels,” places where the channels of a drainage pattern followed the same geological process, becoming more resistant to erosion so that over time it turned from a channel to a ridge.

Here we have a combination of both. The overview map below provides us the larger picture.
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The very end of an 800-mile-long Martian canyon

The very end of an 800-mile-long Martian canyon
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Cool image time! While most geeks interested in Mars are familiar with Valles Marineris, the largest canyon in the solar system, Mars has other large canyons that while not a big are impressive in their own right. The picture to the right, rotated, cropped, and reduced to post here, shows us the very very end of one such canyon. Taken on April 19, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows the easternmost spot where Cerberus Fossae begins. From here, this narrow fracture-caused canyon extends another 800 miles to the west, sometimes splitting into two or three parallel cracks, but always oriented in the same direction, slightly north of due west.

The overview map below provides the context and wider view.
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Martian terraces

Overview map
Glacier country on Mars

Martian terraces
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on May 17, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists have labeled “Dipping layers against mound in Deuteronilus Mensae.”

Deuteronilus is the westernmost mensae region in the 2,000-mile-long strip of heavy glaciers found in the northern mid-latitudes that I dub glacier country. This photo, the location of which is marked by the white cross on the overview map above, is another example, though somewhat strange and puzzling. Normally the layers will dip away from the high point. Here, the layers dip towards the mound. I can think of only one explanation, that of prevailing winds causing the erosion in this unusual manner, but I also find that explanation very unsatisfactory.

The layers themselves illustrate the cycles that have shaped Martian geology, caused by the wide swings in the planet’s rotational tilt, from 11 to 60 degrees. When that tilt is high, the poles are warmer than the mid-latitudes, and water ice migrates from the poles towards the equator. When the tilt is low, the mid-latitudes are warmer, and the water ice heads back towards the poles. Thus, the many many layers the orbiters and rovers are now finding everywhere on Mars.

Right now scientists think, because Mars’ tilt is in the middle of these swings at 25 degrees, the planet is in equilibrium, with the water at the poles and mid-latitudes essentially going no where. This conclusion however is not yet confirmed.

Layered mesa on Mars

Layered mesa on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on May 26, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a mesa about three quarters of a mile in length that appears to be many-layered, from top to bottom.

The brightness of the mesa, compared to the surrounding plains, also emphasizes the different layers, though in this case it suggests two major epochs where the material being laid down in each was fundamentally different.

Or the difference could simply mean that the surrounding terrain is covered with dust, hiding its true color.

There is no question that winds in the thin Martian atmosphere have contributed to the erosion that formed this mesa, much like the buttes in the American southwest are shaped by winds. Whether water was a factor for this Martian butte is far less certain.

The overview map below provides context.
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Icy scarps in the high southern latitudes of Mars

Icy scallops in the high southern latitudes of Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on May 30, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label “Patching Mantling Unit,” located at about 57 degrees south latitude in a region where scientists have found good evidence of near surface ice. The top layer, or mantle, is likely patchy because it has a high content of water ice and is sublimating away. That almost all the cliffs are south-facing, which in the southern hemisphere gets the least direct sunlight, supports this supposition. For example, in the crater at the bottom of the image the ice would have disappeared first from the north-facing interior rim slopes, with the sublimation slowly working its way northward. Thus we have that butte extending out from the north rim.

The global map below not only indicates the location of these scallops with the green dot, it illustrates the overall icy nature of most of the Mars.
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The highest point on Mars

The highest point on Mars
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Today’s cool image is cool not because of anything visible within it, but because of its location. The picture to the right, cropped to post here, was taken on May 27, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). While the terrain shown is a relatively featureless plain of craters and gullies not unlike the surface of the Moon, what we are really looking at is the peak of Mars’ tallest mountain, Olympus Mons.

That’s right, this spot on Mars sits about 70,000 feet above Mars’ mean “sea level”, the elevation scientists have chosen as the average elevation on Mars from its center. At 70,000 feet, this peak is more than twice as high as Mount Everest on Earth.

Yet you wouldn’t really know you are at this height if you stood there. The scale of this mountain is so large that this peak, which actually forms the southern rim of the volcano’s 50 to 60 mile wide caldera, is actually relatively flat. If you stood here, you would not see the vast distant terrain far below. Instead, you’d see an ordinary horizon line in the near distance only slightly lower than where you stand.
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Collapse pits on Mars

Elongated collapse pit on Mars
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Cool image time! The photo to the right, cropped to post here, was taken on May 21, 2022 and was today’s picture of the day from the high resolution camera on Mars Reconnaissance Orbiter (MRO). Dubbed “An Elongated Collapse Pit” by the science team, their caption explains:

This observation can help to tell whether or not there is a subterranean connection to this pit. As an added bonus, the much smaller depression to its south also appears to be another collapse pit.

This image had already been in my queue for a future cool image post, but since the scientists have posted it, it is time that I did as well.

In the inset I have brightened the image drastically to try to illuminate the darkest spots in both pits. The elongated pit appears to slope downward towards a hole in the southeast corner, while the interior of the second pit to the south remains completely dark. Both appear to suggest a void below that both reach.

The wider context image and overview map below shows that there is further evidence of more voids in this region of Mars, dubbed Ceraunius Fossae, because of its many north-south parallel fissures.
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The colorful layers of the Martian north pole icecap

Colorful layers in the Martian north pole ice cap
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Wider view
Click for full image.

Today’s cool image above, rotated, reduced, and annotated to post here, comes from today’s picture of the day for the high resolution camera on Mars Reconnaissance Orbiter (MRO), which in turn is a retrospective of a captioned image first taken in 2010. The photo to the right, rotated, cropped, and reduced to post here, shows a larger area to provide some context. For this image north is towards the top. The rectangle indicates the area covered by the picture above.

The ice cap at the north pole is about 600 miles across and a little less than 7,000 feet deep, made up of many layers that are a mixture of water ice and cemented dust and sand. From the picture’s caption:

In many locations erosion has created scarps and troughs that expose this layering. The tan colored layers are the dusty water ice of the polar layered deposits; however a section of bluish layers is visible below them. These bluish layers contain sand-sized rock fragments that likely formed a large polar dunefield before the overlying dusty ice was deposited.

The lack of a polar ice cap in this past epoch attests to the variability of the Martian climate, which undergoes larger changes over time than that of the Earth.

The overview map below provides some further context.
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From the rim to the floor of Valles Marineris

Overview map

From the rim to the floor of Valles Marineris
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For today’s cool Martian image, we begin from afar and zoom in. The overview map above shows the solar system’s largest canyon, Valles Marineris, 1,500 miles long, and 400 miles wide at its widest. The white dot on the north rim of the section of the canyon dubbed Melas marks the location of the photo to the right, rotated, cropped and reduced to post here and taken on January 28, 2011 by the wide angle context camera on Mars Reconnaissance Orbiter (MRO).

I have added elevation numbers to this picture to give it some understandable scale. From the rim to the interior canyon floor — a distance of about ten miles — the canyon wall drops about 19,000 feet. Compare this with Bright Angel Trail in the Grand Canyon, which from the rim to the Colorado River drops about 4,400 feet in about the same distance. The wall of Valles Marineris is about four times steeper.

Even that doesn’t give you the full scale. Having hiked down to that interior canyon floor, you are still about 10,000 feet above Valles Marineris’s main canyon floor, with fifteen more miles of hiking to go to reach it.

The white rectangle marks the area covered by the MRO high resolution image below.
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How did sand dunes get to the top of a Martian mesa?

Sand dunes at the top of a Martian mountain
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 1, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows one of the peaks of a 5,000+ foot high mesa inside Juventai Chasma, one of Mars’ deep mostly-enclosed chasms north of Valles Marineris.

I grabbed this picture because its label, “Bedform Change Detection in Juventae Chasma”, suggested something had changed from past photos, probably related to the sand dunes that hug the upper slopes of this peak. Unfortunately, in comparing this image with the earliest high-res image taken by MRO back in February 2018, I could not spot any change, probably because the resolution of the pictures released is not as high as MRO’s raw images.

However, the caption written for that 2018 image tells us where that change has likely occurred:

This image reveals a unique situation where this small dune field occurs along the summit of the large 1-mile-tall [mesa] near the center of Juventae Chasma. The layered [mesa] slopes are far too steep for dunes to climb, and bedform sand is unlikely to come from purely airborne material. Instead, the mound’s summit displays several dark-toned, mantled deposits that are adjacent to the dunes and appear to be eroding into fans of sandy material.

In other words, somewhere in the full resolution image scientists have spotted a change in the bedform sands that make-up these high mountain dunes that hug the peak. Since the data so far has suggested that the source for the sand of these high elevation dunes likely comes from the mesa itself — not from any distant source — any change found will help confirm or disprove that hypothesis.

The white box indicates the area covered by the close-up higher resolution picture below. Also below is an overview map, showing both the location of this mountain in Juventai Chasma as well as Juventai’s location relative to Valles Marineris.
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Strange pitted and isolated ridges on Mars

Context camera image of isolated ridges
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on February 17, 2012 by the wide-view context camera on Mars Reconnaissance Orbiter (MRO). It shows a section of the northern lowland plains of Mars, latitude 31 degrees north, where several very inexplicable and isolated ridges can be seen.

One ridge meanders mostly in a north-south direction, while a second instead meanders east-west. The shape of both says that neither has anything to do with any past impact crater. In fact, their random snakelike shape doesn’t really fit any obvious explanation. For example, they do not fit the look of the many fossil rivers found on Mars, where the hardened and dry riverbed channel resists erosion and becomes a ridge when the surrounding terrain erodes away.

What geological process caused them? In the decade since this photo was taken the scientists who use MRO have only been able to snap a handful of high resolution images of these ridges. The image below is the most recent, covering the area in the white rectangle above.
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Glacial features in a Mars crater at 29 degrees south latitude?

Glacial features in Mars crater
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Simply labeled “slope features,” it was likely taken to monitor the gullies and streaks on the interior walls of this 4-mile-wide crater. Scientists have been using MRO to track the coming and going of frost on this crater’s interior walls since 2016.

Equally intriguing however are what appear to be squashed layers within the crater’s interior. These appear to be some form of glacial feature created by repeated climate cycles, similar to the glacial features routinely seen throughout the 30 to 60 degree mid-latitude strips north and south.

What makes the glacial features in this particular crater particularly intriguing is its location, as shown in the overview map below.
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Scientists want your help cataloging the clouds on Mars

In order to fully identify all the clouds seen in the sixteen years of data collected by the cloud instrument on Mars Reconnaissance Orbiter (MRO), scientists have now organized a citizen-scientist project to catalogue those clouds.

The project revolves around a 16-year record of data from the agency’s Mars Reconnaissance Orbiter (MRO), which has been studying the Red Planet since 2006. The spacecraft’s Mars Climate Sounder instrument studies the atmosphere in infrared light, which is invisible to the human eye. In measurements taken by the instrument as MRO orbits Mars, clouds appear as arches. The team needs help sifting through that data on Zooniverse, marking the arches so that the scientists can more efficiently study where in the atmosphere they occur.

You can join up by going here.

A thick and syrupy flow on Mars

A thick and syrupy flow on Mars
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Overview map

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:

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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A snakelike Martian ridge

A snakelike Martian ridge
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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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Water and dry ice at the Martian north polar ice cap

water and dry ice at the Martian north pole
Click for original image. Click here for full image.

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.

Wavy crescent ridges on Mars

Wavy crescents on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on November 19, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team has labeled “Crescentic forms,” which in some ways resemble crescents that I featured in a cool image back in November 2020.

Unlike those earlier crescents, today’s are linked together to form a longer wavy line. Furthermore, today’s crescents include some positive relief, with some parts standing above the surrounding terrain. The earlier crescents were entirely carved out of the ground, forming depressions.

And yet, the method of formation for both must be somewhat similar. I say this based on their location, as shown in the overview map below.
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Spiders galore on Mars!

Spiders galore on Mars
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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.

A high mountain inside Valles Marineris

A high mountain inside Valles Marineris
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Cool image time! The photo to the right, cropped, reduced, and annotated to post here, was taken on January 4, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the flat top of a mountain inside Candor Chasma, one of the side canyons of the solar system’s largest canyon, Valles Marineris.

The image was taken when the sun was about 32 degrees above the horizon, to the west, and thus apparently low enough to put the flat top mostly in shadow.

What is most spectacular about this photo is the sense of scale it portrays once you know the overall context. Note the many layered slope to the west. That slope will continue downward far beyond the left edge of this image, dropping for dozens of miles and about 13,000 feet. The overview map below makes this clearer.
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Martian ridge sticking up out of a lava flood plain

Martian ridge sticking up out of a lava flood plain
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on August 9, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and was featured today as this camera’s picture of the day. As today’s caption notes:

This observation focuses a ridge that is standing above the old lava surface of the floor of Echus Chasma. What is this ridge doing here? Is it preexisting material surrounded by lava? Is it material pushed up at a restraining bend? If the ridge is not lava, it may have colorful flanks.

The overview map below shows that this location in Echus Chasma is even more interesting, as some scientists believe it once also held a large lake.
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Mars: Are these eroding glaciers or impacts in lava?

Eroding lava or glaciers?
Click for original image.

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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Dry flows on Mars?

Flows in Orson Welles Crater
Click for original image.

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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Mountains, Mesas, and Box Canyons on the floor of Valles Marineris

Mountains, Mesas, and Box Canyons
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Overview map

Cool image time! The photo above, cropped, reduced, and rotated to post here, was taken on March 12, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small section of the floor of the giant 2,550-mile-long and 400-mile-wide Valles Marineris canyon on Mars. In fact, this section, as indicated by the black rectangle in the overview map below, is practically in the center of the canyon, at its widest point.

The geology here hints at several Martian processes. The mesas and closed canyons in the north are typical of chaos terrain, where it erosion appears to form along fault lines to create the random intersecting canyons. In other places on Mars, in the mid-latitudes, that erosion appears mostly formed by glacial activity. Here, in Valles Marineris at only 7 degrees north latitude, little ice had been expected.

However, this spot is also in the dead center of a region where orbital data from Europe’s Trace Gas Orbiter (TGO) suggests there is a surprisingly large underground reservoir of hydrogen, which is assumed could only exist if it was locked in water molecules.

In fact, at this spot the data suggests up to 40% of the near-surface material might be composed of water (by weight). If so, that underground reservoir of ice could be causing the erosion that is creating this massive chaos terrain.

Meanwhile, the light-colored mountain in the south is the westernmost nose of a 50-mile-long ridgeline coming down from the canyon’s rim, about 30,000 feet higher. Its dendritic nature, like the hollows that form in the mountains of wet regions on Earth, suggest rainfall and water flowing downhill, wearing away these hollows over eons.

Rain however is almost certainly not the cause. Instead, we could be seeing erosion from wind, or maybe dry ice snow that fell long ago when this region was at a higher latitude when Mars’ rotational tilt was different.

Either way, the massive geology here illustrates the monumental nature of this largest canyon in the solar system, as well as the difficulties of exploring it.

Scientists propose new theory to explain mysterious slope streaks on Mars

Slope streaks on Mars
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In a paper published earlier this month, scientists have proposed a new theory to explain the the origin of slope streaks on Mars, a unique Martian geological feature that at first glance look like a stainlike avalanches which also appear to do nothing to change the surface topography. (See earlier posts here and here for a description of this strange Martian phenomenon.)

Essentially, data from the orbiters suggests that carbon dioxide frost develops just under the surface during the night. In equatorial regions this frost mixes with dust (allowing it to exist even in these warmer climates). When the morning light hits the frost it causes it to sublimate away, which in turn causes the appearance of slope streaks as the dust is released from the frost.

From the paper’s abstract:

At sunrise, sublimation-driven winds within the regolith are occasionally strong enough to displace individual dust grains, initiating and sustaining dust avalanches on steep slopes, forming ground features known as slope streaks. This model suggests that the CO2 frost cycle is an active geomorphological agent at all latitudes and not just at high or polar latitudes, and possibly a key factor maintaining mobile dust reservoirs at the surface.

The cool image above, cropped and reduced to post here, was taken on October 28, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows an excellent example of two very spectacular large slope streaks, one long and narrow and another short and wide. Located at 23 degrees, this is an area where no ice has yet been found near the surface.

This new theory joins two other popular theories attempting to explain slope streaks. The others postulate that the streaks are either dust avalanches of a different type or the percolation of a brine of chloride and/or perchlorate in a thin layer several inches thick close to the surface.

None have been proven. None likely fit all the known data at this point.

Why a big Earth mountain would hardly be noticed on Mars

A big mountain lost on Mars
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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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Brain terrain in Mars’ glacier country

Brain terrain in glacier country
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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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The icy Reull Valley of Mars

Eroded ice in crater near Reull Valles
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the eroded floor of a 10-mile-wide very obscured unnamed crater that sits above the northern wall of a canyon dubbed Reull Valles.

For reference the interior slope of the crater’s southern rim is labelled. The crater sits at 40 degrees south latitude. Thus, this crater is inside the 30 to 60 degree mid-latitude bands where scientists have found many glaciers on Mars. The eroded floor of this crater appears to confirm this conclusion. In the full photo the erosion is even more pronounced, as well as more chaotic, farther from that rim to the north.

Because Reull Valles sits inside that southern glacial band, it is home to much evidence of ice. The overview map below provides the context.
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