Tag Archives: Mars Reconnaissance Orbiter

A gathering of dust devils

Dust devil tracks
Click for full resolution image.

A bunch of cool images! The European Space Agency (ESA) today released more than a dozen Martian images taken by the camera on its Trace Gas Orbiter spacecraft.

In addition to a snapshot of InSight and its landing area, “The images selected include detailed views of layered deposits in the polar regions, the dynamic nature of Mars dunes, and the surface effects of converging dust devils.” The release also included images showing details of two of Mars’ giant volcanoes, Olympus Mons and Ascraeus Mons.

The image I have highlighted to the right, reduced to post here, shows a spot on Mars where for some unknown reason dust devils love to congregate.

This mysterious pattern sits on the crest of a ridge, and is thought to be the result of dust devil activity – essentially the convergence of hundreds or maybe even thousands of smaller martian tornadoes.

Below is a side-by-side comparison of this image (on the right) with a Mars Reconnaissance Orbiter (MRO) image taken in 2009 (on the left).
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Martian massive landslides

Though scientists have found some evidence of slow erosion and change on the Martian surface, it is today generally inactive. While the weak wind of Mars’ thin atmosphere continues to work its will, and the likely presence of underground frozen water acts to shift the surface shape as the seasons come and go, none of this happens quickly.

Essentially, Mars is a quiet place.

Once however catastrophic events took place, gigantic floods flowing down to the east from the planet’s huge volcanoes to carve out Marineris Valles, the solar system’s largest known canyon. As that water rushed eastward it ripped the terrain apart quickly, creating deep side canyons, drainage valleys, and chopped up regions now dubbed as chaos terrain, multiple mesas separated by numerous fissure-like canyons.

Overview of Marineris Valles and landslide

The overview map on the right shows Valles Marineris and its drainage to the east and north into the vast northern plains of Mars. It also shows the location of one of the largest regions on Mars of chaos terrain, dubbed Hydraotes Chaos, located close to the mouth of this gigantic drainage system more than 2,500 miles long.

Massive Martian landslide
Click for full image.

Recently scientists have used the high resolution camera on Mars Reconnaissance Orbiter (MRO) to begin taking images of the massive landslides on the face of the mesa north of Hydraotes Chaos that was hit directly by these floods. The location of the most immediately interesting of these landslide images is also indicated on this overview image.

To the right is that image, rotated, cropped, reduced, and annotated to post here. The white boxes indicate two full resolution sections that I highlight below at full resolution.

This image shows that full cliff. The total drop from the plateau at the top to the floor where Hydraotes Chaos is located to the south is approximately 8,200 feet, almost exactly comparable to the depth of the north rim of the Grand Canyon.

The image shows numerous evidence of avalanches and erosion, both at its base and at its rim. None of these avalanches likely occurred during those catastrophic floods, but long afterward.
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Brain Terrain on Mars

Brain terrain on Mars
Click for full image.

Cool image time! This week the Mars Reconnaissance Orbiter (MRO) science team featured four new captioned images taken by the spacecraft and released as part of the March image dump. The first, dubbed “The Slow Charm of Brain Terrain,” deserves an immediate post on Behind the Black. To the right is only a small section cropped from the full image. From the caption:

You are staring at one of the unsolved mysteries on Mars. This surface texture of interconnected ridges and troughs, referred to as “brain terrain” is found throughout the mid-latitude regions of Mars. (This image is in Protonilus Mensae.)

This bizarrely textured terrain may be directly related to the water-ice that lies beneath the surface. One hypothesis is that when the buried water-ice sublimates (changes from a solid to a gas), it forms the troughs in the ice. The formation of these features might be an active process that is slowly occurring since HiRISE [MRO’s high resolution camera] has yet to detect significant changes in these terrains.

Below is a cropped section of the full image, rotated and reduced to post here.
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Waterlike Martian lava flows

Flowing like water
Click for full image.

Each month the Mars Reconnaissance Orbiter (MRO) science team highlights with captions about four out of the 300-500 new images released that month.

Of the four captioned images in February, the first was entitled “Almost Like Water,” and focused on the waterlike nature of the lava flow. The image on the right is a cropped and annotated section of that featured photograph, with the yellow arrows indicating the flow directions.

The lava appears to have flowed smoothly around obstructions, almost like water, forming streamlined islands. In the southern part of this image, a branch of the flow diverts around a small crater, and eventually rejoins the main part of the flow. [Visible in the full photograph] Irregular-shaped ring structures appear on the northern end and are related to the volcanic activity that formed the flows.

You can see an example of one of those islands near the top of the above image.

This is hardly the only MRO image showing such flows. In fact, the February image release included a bunch, some of the more intriguing of which I highlight below. These lava flows are seen in many different places on Mars, in a wide variety of geological settings, facts that suggest that volcanic activity was once very widespread and ubiquitous on Mars.
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Another batch of caves/pits found on Mars

Four new pits on Mars

Overview of February 2019 pits

In the past year the monthly image releases from the high resolution camera on Mars Reconnaissance Orbiter (MRO) archive have frequently included newly discovered pit entrances. Each time I have written posts highlighting these new pits, in June, July, November 2018 and January 2019. In fact, this is happening so frequently I could almost label it a monthly update!

The November release imaged three pits found on the southern flanks of Arsia Mons. The January 2019 release found several north of the volcano, two of which are very close to the two middle new pits highlighted above. The February release, which is the focus of this post, included four more pits, shown above, all located north and west of Arsia Mons, as shown in the overview map to the right.

Pits 2 and 3 above appear to belong to a cluster of pits all located in the general area between Arsia and Pavonis Mons. (You can see their uncaptioned releases here and here.) Most sit alone on a flat somewhat featureless plain. Sometimes there are flow features nearby, but each pit usually seems to sit unique and unrelated to these other faint features.

Pit 1 is very intriguing in that it sits amid a very long chain of pits and canyons, all aligned, as shown in the image below and to the right.
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Rover update: February 20, 2019

Summary: Curiosity in the clay unit valley. Opportunity’s long journey is over. Yutu-2 creeps to the northwest on the Moon’s far side.

For the overall context of Curiosity’s travels, see my March 2016 post, Pinpointing Curiosity’s location in Gale Crater.

For the updates in the past year go here. For a full list of updates before February 8, 2018, go here.

Curiosity

Curiosity's view to the east on Sol 2316
Click image for full resolution version

Overview of Curiosity's future travels
Click image for original image

Since my January 22, 2019 update, Curiosity finally drove down off of Vera Rubin Ridge into a valley between the ridge and the lower slopes of Mt Sharp. The Mars Reconnaissance Orbiter (MRO) overview on the right has been annotated by me to show the rover’s travels (shown by the yellow dotted line), with its proposed route indicated by the red dotted line. The yellow lines indicate approximately the terrain seen in the panorama above. The panorama was created from images taken on Sol 2016.

The valley that Curiosity is presently traversing is dubbed “the clay unit” or “the clay-bearing unit” by the geologists, based on its make-up determined from orbital data. So far they have found this terrain to be “some of the best driving terrain we’ve encountered in Gale Crater, with just some occasional sandy patches in the lee of small ridges.” Initially they had problems finding any rocks or pebbles large enough for the instruments to use for gathering geological data. For the past week or so, however, they have stopped at “bright exposure of rock” where some bedrock was visible, giving them much better material to work with.
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A river valley floor on Mars

Overview of Reull Valles region

Today’s cool image focuses in on a Mars Reconnaissance Orbiter (MRO) uncaptioned photograph taken of the valley floor of Reull Vallis, a meandering canyon that drains into Hellas Basin, the bottom of Mars.

The image on the right is not that photograph. Instead, it is an overview of the area surrounding it. The image location is indicated by the black cross, dead center within the floor of Reull Vallis itself. This valley, as well as Dao and Niger to the northwest but lower in elevation are all thought to have been formed from flowing water, all of which apparently drained from the east and to the west into Hellas Basin.

This last detail is very important and bears repeating before looking at today’s subject image. The river that formed Reull Vallis flowed from the east to the west. Now for that picture.
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Monitoring a fresh-looking Martian landslide

2012 image of Martian landslide
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2018 image of Martian landslide
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Time for two cool images! To the right are two images taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the top one taken in April 2012, and the bottom taken in December 2018. Both have been cropped and reduced slightly in resolution to post here.

The second image is trying to answer, in only a small way, one of the most fundamental questions of the Martian environment: How fast does it change? The images from orbit have periodically seen evidence of new impacts. MRO images have tracked dust devil tracks. And we know that somehow water, ice, wind and volcanic activity have eroded and reshaped the surface over eons.

What we don’t know truly and with detail is the pace of these changes, with any accuracy. The pace of some things over time seems obvious. For example, Mars’s inactive but gigantic volcanoes suggest that once volcanism was very active, but over time has ceased so that today it is unclear if any is occurring. Similarly, the geological evidence suggests that in the far past water flowed on the surface, producing catastrophic floods. Now that liquid water is all but gone, and this erosion process as ceased.
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Strange crescent-shaped pit near Martian south pole

crescent-shaped pit near Martian south pole

Cool image time! The south polar cap of Mars is a strange place. It is largely ice, with a seasonal cap of frozen carbon dioxide, or dry ice. Because the dry ice sublimates away during the summer months, the cap undergoes regular changes that reshape it, producing alien features that are not seen on Earth.

The image on the right is another example of these alien features. I found it in the February image release from the high resolution camera on Mars Reconnaissance Orbiter. I have merely cropped the full image to focus at full resolution on its primary feature, a region of stippled-like surface surrounding an area of black striping that in turn surrounds a crescent-shaped pit outlined by whiter material.

Why is there a pit here? Why is it crescent-shaped? Why is it surrounded by that whiter material? I could guess and say that the pit is a vent from which water vapor from the lower cap of water sprays out onto the upper cap of frozen carbon dioxide, staining it with white ice, but I am most likely wrong.

Moreover, what causes the black striping, as well as the stippled material surrounding it? The black stripes are probably related to a similar process that forms the spider formations found in the polar regions, except that these are not spiders. Why the parallel straight lines?

A lot of questions with no answers. While many features on Mars are strange, the features near the poles are probably stranger still, as they form in a place with chemistry, temperatures, gravity, and materials in a combination and scale that we on Earth have no experience with.

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Mysterious dark-toned Martian terrain

Dark toned ridge in Martian southern highlands
Click for full resolution image

Cool image time! The picture on the right, cropped and reduced to post here, was part of the January image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO). It shows an area in the Martian southern highlands where the surface suddenly gets darker, for no obvious reason.

The uncaptioned release image is titled “Dark-Toned Ridge at Junction with Dark-Toned Plain.” From the image itself it is hard to understand this title. In the full image the darkest terrain is a strip in the center, with slightly lighter dark terrain on either side, and the lightest terrain to the north or south. The photograph however does not show us how far this dark terrain extends to the west or east.

Two Mars Odyssey image strips of less resolution, here and here, show that this region is filled with several large patches of dark-tone surface. With this particular patch the center dark ridge is surrounded by that slightly lighter dark area.

MRO itself has not taken many images of this region, as shown in the overview image below. The red rectangles indicate MRO’s high resolution photographs, with this image indicated by the cross. At this low resolution this region seems somewhat nondescript. The Mars Odyssey image strips show that there many features here, but with little significant relief.

Location of dark toned ridge

At high resolution there does not appear to be much difference between the darker and lighter areas. The lighter areas in general seem less rough and at a slightly lower elevation, but both areas are dominated by ridges and dunes trending southwest-to-northeast.

Why is this slightly higher region darker? Let’s assume that this darker material was a lava flow overlaying the surface. Over eons wind erosion, trending southwest-to-northwest, roughly eroded both it and the lower layers around it, leaving behind this rough corroded terrain. The different make-up of the darker material allows it to erode in a rougher manner.

While possibly correct, I would not bet much money on this guess. It is not clear it is lava. It is not clear that it is a flow. It does not explain why there are two areas of different darkness. And it certainly not clear what the make-up of any of this stuff is.

This is simply another cool mystery on the Martian surface.

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Strange fernlike ridges on Mars

Fernlike ridges on Mars

Cool image time! The two images on the right, cropped, rotated, and reduced in resolution to post here, were both taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO). To see the full resolution version of each, go to the 2009 and 2018 releases.

The 2009 release was a captioned release, whereby scientist Alfred McEwen of the science team provided his explanation of these strange features.

The dark branched features in the floor of Antoniadi Crater look like giant ferns, or fern casts. However, these ferns would be several miles in size and are composed of rough rocky materials.

A more likely hypothesis is that this represents a channel network that now stands in inverted relief. The channels may have been lined or filled by indurated materials, making the channel fill more resistant to erosion by the wind than surrounding materials. After probably billions of years of wind erosion the resistant channels are now relatively high-standing. The material between the branched ridges has a fracture pattern and color similar to deposits elsewhere on Mars that are known to be rich in hydrated minerals such as clays.

These strange fernlike features do not appear to be very common on Mars. In fact, I suspect that while Mars does have many inverted channels like this, the fernlike nature of these particular channels is unique on Mars. They are located on the floor of Antoniadi Crater, a large 240-mile-wide very ancient and eroded crater located in the Martian southern highlands but near the edge down to the northern lowlands.

In seeing the new 2018 image, I was immediately compelled to place it side by side with 2009 image to see if anything had changed in the ensuring near-decade. There are color differences, but I suspect these are mostly caused by different lighting conditions or post-processing differences. Still, the dark center to the crater in the upper left of both images suggests a change in the dust dunes there, with the possibility that some of the dust has been blown from the crater over time. Also, you can see two horizontal tracks cutting across the center of the 2018 image, which I would guess are dust devil tracks, with one more pronounced.

I can imagine some planetary geologists have spent the last few months, since the second image was taken, pouring over both photographs, and have might even located other interesting changes. And if they find no significant changes, that in itself is revealing, as it gives us a sense of the pace at which the Martian surfaces evolves.

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The many pits/caves of Mars

Sinkhole in Martian northern lowlands with dark seep

Time for many cool images! Over the years I have written frequently about the pits/caves on Mars, in both magazine articles and the many posts here at Behind the Black. The following posts are the most significant, with the June 9, 2015 providing the best geological background to many of these pits, especially the many located near the giant volcanoes of Mars.

As I wrote in that June 9, 2015 post:
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Weird Martian fracture feature

Fractured collapse feature on Mars

Cool image time! When I first looked at the high resolution Mars Reconnaissance Orbiter (MRO) image on the right, my immediate reaction was, “What the heck is that?” The image to the right is cropped and reduced, but if you click on it you can see the full image at high resolution.

The fractured terrain appears to be all within a collapse. To my eye it appears that while the overall surface has sunk, the fractures indicate an area where there has been an eruption upward, which after the eruption collapsed again, so that the fractured area remains at the apparent bottom of the collapse sink. I was immediately reminded of Upheaval Dome in Yellowstone National Park, which some geologists believe was formed by a “salt bubble” rising upward to create a salt dome.

A thick layer of salt, formed by the evaporation of ancient landlocked seas, underlies much of southeastern Utah and Canyonlands National Park. When under pressure from thousands of feet of overlying rock, the salt can flow plastically, like ice moving at the bottom of a glacier. In addition, salt is less dense than sandstone. As a result, over millions of years salt can flow up through rock layers as a “salt bubble”, rising to the surface and creating salt domes that deform the surrounding rock.

Context image for fracture feature

The process and materials involved were certainly different on Mars. Nonetheless, it does appear we are looking at an eruptive feature unrelated to molten lava. The context image to the right, showing this feature’s location in Mars’ vast northern lowlands, also shows that it has occurred on terrain that has bulged upwards relative to the surrounding lowlands. Nearby MRO images also show similar bulge/collapse features.

To decipher the geological mystery here, we would also need to know when this happened and whether there ever was a liquid ocean residing on top of it, before, during, or after the eruption. We also do not know well the make-up of the underground materials, including whether any frozen water and salt is present.

To be honest, we really don’t know much. I am sure a planetary scientist studying this feature could fill us in on some of these details, such as information provided by the colors in the color image. Even so, I am sure any good scientist would also admit to unknowns.

To get some real answers, we need to be there. It is as simple as that.

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Martian glacier with moraine?

Glacier flow on Mars, with moraine

Cool image time! In the past two decades numerous images and studies of the Martian terrain produced by orbiters have shown us landslides, lava flows, water and ice produced flows, and many glacial features, all vaguely familiar but often having components reminding us of the alien nature of the Martian landscape. I have posted many here at Behind the Black. (Just do a search here for the words “Mars flow” and you will have a wealth of cool images and alien geological features to explore.)

The image on the right, rotated, cropped, and reduced to post here, shows another such feature, but this time it is less alien and more resembling a typical Earth glacier, flowing downhill slowly and pushing a moraine of debris before it. The picture was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and was part of the January image release. If you click on the image you can see the complete photograph at full resolution.

The release has no caption, but is titled “Tongue-Shaped Glacier in Centauri Montes,” referring to the largest tongue-shaped flow on the left. This feature, more than any other in the image, resembles closely many glaciers on Earth. It even has an obvious moraine at its head. As the glacial flow pushed downward slowly it gathered a pile of material that eventually began to act almost like a dam.

The location of this feature is intriguing in its own right.
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New impact on the Martian south polar cap

New impact on Mars' south pole

Cool image time! The image to the right, cropped to post here, was taken on October 5, 2018 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a recent meteorite impact that occurred sometime between July and September of 2018 on the Martian polar cap . If you click on the image you can see the entire photograph. As noted in the captioned press release,

It’s notable because it occurred in the seasonal southern ice cap, and has apparently punched through it, creating a two-toned blast pattern.

The impact hit on the ice layer, and the tones of the blast pattern tell us the sequence. When an impactor hits the ground, there is a tremendous amount of force like an explosion. The larger, lighter-colored blast pattern could be the result of scouring by winds from the impact shockwave. The darker-colored inner blast pattern is because the impactor penetrated the thin ice layer, excavated the dark sand underneath, and threw it out in all directions on top of the layer.

Location on edge of south polar cap

It is not known yet the size of this meteorite. The location is shown in the overview image to the right, with the impact indicated by the white dot. The black circle in the middle of the image is the south pole itself, an area where MRO’s orbit does not allow imagery. This location, on the edge of the Martian polar cap, is helpful to scientists because it has excavated material from below the cap, providing them a peek into previously unseen the geology there. Had the impact been farther south, on the thicker cap, that hidden material below the cap would likely not have been exposed.

The cap itself is made up of both ice and frozen carbon dioxide, though the CO2 is mostly seen as frost during winter months that evaporates during the summer.

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Volcanic vent between Arsia and Pavonis Monsa

volcanic vent on Mars

Cool image time. The photo on the right, rotated, cropped, and reduced to post here, was taken in September by the high resolution camera of Mars Reconnaissance Orbiter (MRO) and was part of the November image release. Click on the image to see the entire photograph at full resolution.

The uncaptioned release dubs this feature as “Small Eruptive Vents South of Pavonis Mons.” In truth, these vent pits are located almost exactly the same distance from both Pavonis Mons, the middle volcano in the line of three giant Martian volcanoes, and Arsia Mons, the southernmost of the three.

The image is interesting for several reasons. First, note the bulge surrounding the vent, making this look almost like a miniature volcano all its own. In fact, that is probably what it is. When it was active that bulge was likely caused by that activity, though it is hard to say whether the bulge was caused by flow coming from out of the vent, or by pressure from below pushing upward to cause the ground to rise. It could even have been a combination of both.

To my eye, most of the bulge was probably caused from pressure from below pushing upward. The edge of the bulge does not look like the leading edge of a lava flow. Still, this probably happened so long ago that Martian wind erosion and dust could have obscured that leading edge.

That this is old is indicated by the dunelike ripples inside the large pit, and the pond of trapped dust in the smaller pit. Because of the thinness of the Martian atmosphere it takes time to gather that much dust, during which time no eruptions have occurred.

One more interesting detail: If you look at the pits in full resolution, you will see that, based on the asymmetrical wind patterns between the west and east rims, the prevailing winds here are from the west. Located as it is just to the east of the gigantic saddle between Arsia and Pavonis Mons, this wind orientation makes sense, as a saddle between mountains tends to concentrate the wind, much like a narrowed section in a river produces faster water flow and rapids. As for why the wind blows mostly from the west, my guess (which should not be taken very seriously) is that it is probably caused by the same meteorological phenomenon that causes this generally on Earth, the planet’s rotation.

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Weird erosion in large Martian craters

Central pit in Asimov Crater

Cool image time! In reviewing the images in the December image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO, I came across the image to the right, cropped, rotated and reduced to post here, showing the western half of the central pit of Asimov Crater. (Click on the link for the entire photograph.) The eastern half can be seen here.

It is unusual to see central pits in craters. One instead expects to see central peaks. The pit itself is intriguing because of its sinkhole appearance. In both the northwest and southwest corners you can clearly see drainages flowing down into the pit, including recent faint darkened streaks indicative of past seep avalanches. The same can been seen for the pit’s eastern half. Along the pit’s western rim are parallel cracks suggesting that the plateau itself is slowly shifting downward into the pit.

Furthermore, the rim cliff has multiple drainage gullies, all beginning just below the initial top layers. The look of those cliffs is very similar to what sees on the walls of the Grand Canyon, where the top of the cliffs show layers with the bottom of the cliffs buried under a slope of alluvial fill, material that has fallen to slowly form those slopes. The drainage gullies however would have come later, and suggest that some form of seepage is coming out of the contact between the layers at the top of the slope.

A look at the context image below and to the right reveals the greater mystery of this crater, as well as nearby Maunder Crater, the subject of a recent captioned image release from Mars Odyssey.

context map showing Asimov and Maunder Craters

In both cases a circular interior gully separates the crater floor from the crater’s rim. In fact, the crater floor almost appears raised. This is especially striking with Asimov Crater, where the central floor appears like a very flat plateau, except for that central pit and the surrounding gully.

The MRO team has taken a lot of images of the gullies, which you can see if you zoom in to latitude -46.843° longitude 4.831° on the map image at this website. It is clear that they want to know more about the origins of this geology. It suggests water flow, even though these craters are located in the Martian southern highlands, a place that is more reminiscent of the Moon, with many ancient craters and far less evidence of significant change.

What the geology in these two craters suggest is that some erosion process is eating away at the crater floors, beginning at its edges as well where there are voids below that allow the surface to sink. While that erosion is certainly helped by wind, it also implies the presence of underground water, either as ice or liquid, in the past and even possibly today.

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Lopsided ejecta from Martian crater

Crater with unequal ejecta

Cool image time! The image on the right, reduced and cropped to post here, comes from the December image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO). (If you click on the image you can see the full resolution uncropped photograph.) Released without a caption, the release itself is intriguingly entitled, “Crater with Preferential Ejecta Distribution on Possible Glacial Unit.

The uneven distribution of ejecta material around the crater is obvious. For some reason, the ground was preferentially disturbed to the north by the impact. Moreover, the entire crater and its surrounding terrain look like the impact occurred in a place that was saturated somewhat with liquid, making the ground soft like mud.

That there might have been liquid or damp material here when this impact occurred is reinforced by the fact that this crater is located in the middle of Amazonis Planitia, one of the larger regions of Mars’ vast northern lowland plains, where there is evidence of the past existence of an intermittent ocean.

This however really does not answer the question of why most of the impact’s ejecta fell to the north of the crater. From the release title is appears the planetary geologists think that this uneven distribution occurred because the impact occurred on a glacier. As the ground has a lighter appearance just to the south of the crater, I suspect their reasoning is that this light ground was hard bedrock while the darker material to the north was that glacial unit where the ground was more easily disturbed.

This is a guess however (a common requirement by anyone trying to explain the strange features so often found on the Martian surface). Other theories are welcome of course, and could easily be correct as well.

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Flowing cracked mud on Mars?

mud cracks in crater?

Cool image time! The image on the right, rotated, cropped, and reduced to post here, comes from the December image release of the high resolution camera of Mars Reconnaissance Orbiter (MRO. Uncaptioned, the release titles this image “Cracks in Crater Deposit in Acheron Fossae.” If you click on the image you can see the entire photograph at full resolution.

Clearly the cracks appear to be caused by a downward slumping to the north, almost like a glacier made of mud. We can also see places on the image’s right edge where the mud appears to have flowed off a north-south trending ridge, then flowed downhill to the north. All of this flow is away from the crater’s central peak, which is only partly seen in the photograph near the bottom. That section is the central peak’s southwestern end, with the whole peak a ridge curving to the northeast beyond the edge of the image.

At the north edge of this mud flow the cracks become wider canyons, as if long term erosion is slowing washing the mud away. The flow then stair steps downward in a series of parallel benches. Meanwhile, in the flat central area of the mud flow above can be seen oblong depressions suggesting sinks that also flow to the north.

crater context overview

You can get a better idea of the crater’s overall floor and central peak by the low resolution context image to the right. The white rectangular box indicates the area covered by the full image above. A close look at this part of the crater floor suggests to me a circular feature like a faint eroded smaller crater that includes as its eastern rim the larger crater’s central peak. This impression suggests that the flows seen in the full resolution image are heading downhill into the lowest point of this smaller crater, that upon impact had reshaped the larger crater’s floor.

This impression however is far from conclusive. The features in the large crater could simply be the random geology that often occurs in the floors of impact craters.

What makes this particular mud slide most interesting, as is usually the case for most Martian terrain, is its location.
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Dust devil tracks on the Martian southern highlands

Dust devil tracks

Today’s cool image is cool because of how little is there. The image to the right, cropped to post here, was part of the December image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). The uncaptioned release labeled this image simply as “Southern Intercrater Plains.” Located in the Martian southern highlands, this location is located almost due south of Arsia Mons, the southernmost in the chain of three giant volcanoes to the west of Marineris Valles (as indicated by the white dot on the overview image below).

If you click on the image you can see the entire photograph, though in this case it won’t show you much else than in the excerpt to the right. The terrain here appears flat. The only features of note are some small knobs and the random dark lines that are almost certainly accumulated dust devil tracks. There are also many dark spots, which might also be the shadows of even smaller knobs, but could also be instrument artifacts. I am not sure.

Location of dust devil image

The southern highlands are mostly cratered, with few signs that water ever flowed there. This image for example gives the impression of a vast lonely terrain that has changed little since the very earliest days of Mars’ history.

I expect that scientists could possibly assign some age to this terrain, merely by studying the dust devil tracks. If we calculate how often dust devils might traverse this place, and then count the tracks, assigning their order by faintness, with the faintest being the oldest, it could be possible to obtain a rough age of the oldest tracks.

Still, all that would do would tell us the approximate length of time in which a dust devil track can remain visible. And even if this is a long time, it doesn’t constrain the age of the surface very much, as the weather on Mars has certainly changed with time, especially because we think the atmosphere was once thicker.

What formed this flat terrain? My first guess would be a lava flow, caused when the numerous nearby craters were formed by impact. These craters were likely created during the great bombardment between 3 and 4 billion years ago, and while they have certainly been modified more than lunar craters because of the presence of an atmosphere on Mars, they are likely to have not changed much during that time. Similarly, this flat terrain is likely much like it was, several billion years ago. Dust devils have deposited dust and their tracks, but the hard bedrock remains as it was soon after it solidified.

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Dried mud cracks on Mars?

Mud cracks on Mars?

Cool image time! The image to the right, cropped and rotated to post here, was one of the uncaptioned photographs in the December Mars Reconnaissance Orbiter (MRO) image release. If you click on the image you can see the entire photograph. I have cropped the most interesting area, though cracks can be seen in other areas in the image.

What we appear to have here is a darker lower valley filled with dried mud, which over time has cracked as it dried. At its edges there appear to be ripples, almost like one sees on the beach as waves wash the shore. The perimeter slopes even show darker streaks as if the water in some places lapped up the slopes, and in others flowed downward into the valley.

Later, several meteorite impacts occurred, the largest of which produced concentric dried cracks on its outside perimeter. This impact also provides a rough idea of the depth of the mud in this valley.

Mud of course suggests that this lower valley once was filled with water. Was it? It is not possible now to come to a firm conclusion, but this image’s location shown by the red dot in the overview map below and to the right, provides a clue that strengthens this hypothesis.
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Curiosity’s future travels

MRO image of Curiosity's future travels

In the December release of images from the high resolution camera on Mars Reconnaissance Orbiter (MRO), there was one image entitled “Monitor Region Near Curiosity Rover.” To the right is a reduced, cropped, and rotated section of that image, annotated by me to show Curiosity’s future planned route (indicated by the yellow line). If you click on the image you can see the untouched full resolution version.

Curiosity’s journey has not yet brought it onto the terrain shown in this image. (For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.) The rover is right now just off the left edge of the photograph, on the white ridge dubbed Vera Rubin Ridge visible in the uppermost left. This week it completed the last planned drill sampling on that ridge, and it will soon descend off the ridge and begin heading along the yellow route up the mountain. The white dots along its future route are the locations of recurring slope lines, believed to be seasonal seeps of brine coming from below and causing gentle landslides that darken the surface. As you can see, they hope to get very close to the first seep, and will observe the second from across the canyon from a distance of about 1,200 feet.

The peak of Mount Sharp is quite a distance to the south, far beyond the bottom of the photograph. Even in these proposed travels the rover will remain in the mountain’s lowest foothills, though the terrain will be getting considerably more dramatic.

Below is a full resolution section of the image showing the spectacular canyon to the south of that second seep. This is where Curiosity will be going, a deep canyon about 1,500 feet across and probably as deep, its floor a smooth series of curved layers, reminiscent of The Wave in northern Arizona. The canyon appears to show evidence of water flow down its slopes, but that is unproven.
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Dark dunes, wedding cake mesas, and dust-filled gullies

Dark dunes, wedding cake mesas, and dust-filled gullies

Cool image time! The photo on the right, reduced, rotated, and cropped slightly to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and issued by the spacecraft science team in its December image release.

They didn’t give this image a caption. The release title, “Arabia Terra with Stair-Stepped Hills and Dark Dunes,” significantly understates the wild variety of strange features throughout this terrain. Normally I crop out one section of the photographs I highlight to focus on the most interesting feature, but I couldn’t do it this time. Click on the image to see the full resolution version. Take a look at the complex wedding cake mesas in the lower left. Look also at the streaks of dust that I think are filling the gullies between these hills. In the image’s upper left are those dark dunes, scattered between dust ripples and small indistinct rises and what appears to be a drainage pattern descending to the north. Interspersed with these dunes near the center of the image are several perched crater floors, indicating that the crater impacts happened so long ago that the surrounding terrain had time to erode away, leaving the crater floor hanging like a small plateau.

On the right the two largest mesas rise in even stair-stepped layers that would do the mesas in the Grand Canyon proud.

This could very well be the coolest image I have ever posted. Everywhere you look you see something different, intriguing, and entirely baffling.

Arabia Terra covers the largest section of the transition zone between Mars’s high cratered south and its low flat northern plains, where some scientists believe an intermittent ocean might have once existed. It lies to the east of Valles Marineris, and is crater-filled with numerous intriguing geology, as this image most decidedly illustrates. In this particular case it shows the floor of one of the region’s mid-sized craters.

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The vast southern highlands of Mars

Small section of Rocky Highlands

Rocky highlands

Cool image time! This week the Mars Reconnaissance Orbiter (MRO) science team made available its monthly release of new images taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image above is just a small cropped section from one of those new images, released under the name “Rocky Highlands.” The image on the right is a cropped and reduced section of the full photograph, with the white box indicating the small section above. If you click on either you can see the full resolution uncropped photograph and explore its complex and rough terrain.

What should immediately strike you looking at the small inset section above is the difficulty anyone is going to have traversing this country. There are no flat areas. Every inch seems to be a broken and shattered collection of ridges, pits, craters, or rippled dunes. And the inset above is only a tiny representation of the entire image, all of which shows the same kind of badlands.

This forbidding place is located in the southern highlands of Mars, north of Hellas Basin and south of the transition zone that drops down to the northern lowland plains. The white cross on the map below indicates the image location, with green representing the transition zone, blue the northern plains, and red/orange the southern highlands..
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The bottom of Mars

Hellas Basin ripples

Cool image time! The photo on the right, cropped and reduced to post here, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on May 2, 2018, and shows some very strange ripples and erosion features in one of the lowest elevation locations on Mars, inside Hellas Basin. If you click on the image you can see the full photograph, at full resolution. There are a lot of strange features here, so make sure you take a look at it. The ripples highlighted in the image are between what appear to be three lower basins, and seem to my eye to be ridges created as liquid ebbed and flowed in the basins, depositing material at the shoreline at repeatedly higher and lower levels.

hellas basin

This particular location is not only in Hellas Basin, but it is also located in the deepest part of Hellas, a curved valley located in the basin’s northwest quadrant, as shown by the darker areas in the overview image to the right. The red boxes are other MRO high resolution images, with the cross indicating where this image is located.

This is the bottom of Mars, what could be called its own Death Valley. The difference however is that unlike Death Valley, conditions here could be more amendable to life, as the lower elevation means the atmosphere is thicker. The ripples also suggest that liquid water might have once been here, a supposition supported by other low area images of Hellas Basin, most of which show a flattish dappled surface that to me resembles what one would think a dry seafloor bed would look like The image in this second link also shows what looks like ghost craters that over time became partly buried, something one would also expect to happen if they were at the bottom of a lake, though this could also happen over time on Mars with wind erosion and the movement of dust.

It is also possible that these features come from lava events, so please take my theorizing here with a great big grain of salt. At the same time, recent results have found evidence of paleo lakes scattered all along the eastern rim of the basin, reinforcing the possibility that these were water filled lakes once as well.

Nonetheless, the ripples in the first image above are truly fascinating, as it is clear that at the highest peaks erosion has ripped those peaks away, leaving behind a hollow shaped by the ripples themselves. These features remind me of some cave features I have seen, where mud gets piled but by water flow, and then is over time covered with a crust of harder calcite flowstone. Later, water then washes out the mud underneath, leaving the curved flowstone blanket hanging in the air.

Here in Hellas Basin it looks like something similar has happened, except that at these peaks the outside crust got broken away, allowing wind to slowly suck out the material underneath, leaving these ripple-shaped pits. Whether it was liquid water or lava that helped create these features, the geology left behind is both beautiful and intriguing. I wonder at the chemical make-up of the crust as well as the materials below. And I especially wonder if there is water sources buried within Hellas Basin.

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Volcanic rivers on Mars

Granicus Valles

Cool image time! The photo on the right, cropped and reduced to post here, was part of the November image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). If you click on the image you can see the full resolution picture.

The uncaptioned release webpage is dubbed “Faults in Granicus Valles.” The image itself only shows a small part of Granicus Valles, named after a river in Turkey, that flows down from the estern slopes of the giant volcano Elysium Mons. While far smaller than the four big Martian volcanoes in the Tharsis region to the east and near Marines Valles (which I highlight often), Elysium Mons still outshines anything on Earth at a height of almost 30,000 feet and a width of 150 miles. It sits at about the same northern latitude of Olympus Mons, but all by itself, rising up at the very northern edge of the transition zone between the southern highlands and the northern plains, with the vast Utopia Basin, the second deepest basin on Mars, to the west.

Overview of Elysium Mons and Granicus Valles

Granicus Valles itself is almost five hundred miles long. At its beginning it flows in a single straight fault, but once it enters the northern plains of Utopia Basin it begins to meander and break up into multiple tributaries. The MRO image above shows only a tiny portion in the northern plains, as illustrated by the white box in the overview map to the left.
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More Pits on Mars!

Pits near Arsia Mons

Cool image time! In the November image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO) were three images, dubbed by me in the collage above as number one, number two, and number three, showing pits south of Arsia Mons, the southernmost volcano in the chain of three giant volcanoes to the east of Mars’s largest volcano, Olympus Mons, and to the west of the Marineris Valles valley.

Mars overview showing pit locations

The image on the right provides the geographical context of the three pits. They are all south of the volcano on the vast lava flow plains that surround it. The location of pits #1 and #2 is especially intriguing, on the east and west edges of what appears to be a large lava flow that had burst out from the volcano, leaving a large lava field covering a vast area several hundred miles across just to the south. You can also see a similar large lava field to the north of the volcano. Both fields appear to have been formed when lava poured through the breaks created by the fault that cuts through the volcano from the northeast to the southwest.
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Puzzling fractures on Mars

Fractures on Mars

Cool image time! Today the Mars Reconnaissance Orbiter (MRO) science team released another month’s worth of images from the spacecraft’s high resolution camera. The picture on the right, reduced in resolution to post here, was the first image that I took a close look at, and decided it was worth posting immediately. If you click on the image you can see the full resolution version.

This image lacks a caption, but the release webpage is titled “Fractured Crater Floor.” It shows several cross-crossing fissures, some wide enough for dust to gather within into sand dunes. The fractures themselves appear to be cutting across a bulging dome.

My first reaction was to wonder where the heck this crater was on Mars, how big was it, and how dominate were the fractures within its floor. The image itself does not answer any of these questions. The fractures could be filling the floor, or not, and the crater could be small or big. Moreover, its location might help explain the cause of the fractures.

To understand any of the images from MRO it is always important to zoom out to get some context.
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The vast northern plains of Mars

The vast northern plains of Mars

Cool image time! Actually, this image, found in the October image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO), is not that interesting, in its own right. Context is all!

The image on the right is a small section cropped and reduced in resolution from the full image, which you can see by clicking on it. It shows one of the only interesting features in this long image strip, a small mesa sticking out all by itself in a flat featureless plain pockmarked by various small craters.

The release has no caption, though it is entitled “Northern Plains Survey.” The northern plains, while having a lot of interesting features that attract the attention of planetary scientists and thus get photographed at high resolution, is mostly featureless, at least at the resolution of the wide field survey cameras on many Mars orbiters. In order to know what is really there, they need to take high resolution images systematically, of which this image is obviously a part.

Overview image

The problem is that there is so much ground to cover. This particular image was taken of a spot in the middle of the plains just to the north of the drainage outlets from Valles Marineris, as shown by the context map to the right. The tiny white spot to the right in the middle of the blue plains north of those drainage outlets is the location of this image.

Detail area of overview map

To understand how much ground needs to be covered, to the right is a close-up of the area shown by the white box in the first image above, with red rectangles indicating where MRO has already taken images. The white cross is the subject image. As you can see, most of this immense plain has not yet been imaged. It is almost as if they threw a dart to pick this one location. Most everything around it remains unseen at high resolution. Thus, to understand the geology of this one image is hampered because the surrounding terrain remains unknown, in close detail.

Mars is a big place. It is an entire planet, with the same land surface as the Earth’s continents. It still contains many mysteries and unexplored places. It will take generations to see it all.

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The steep slumping wall of a Martian volcano caldera

Caldera wall

Cool image time. The Mars Reconnaissance Orbiter science team today released a nice captioned image of the steep wall of the caldera of Ascraeus Mons, the northernmost of the three giant volcanoes that lie to the east of Olympus Mons, the biggest volcano of all. The image on the right, reduced and cropped, shows that steep wall, with full image available by clicking on it. The caption from the release focuses on the fluted upper parts of the wall.

We can see chutes carved into the soft dust that has built up on the slope, with some similarities to gully landforms elsewhere on the planet.

More revealing to me is how this image reveals the slumping that is slowing eroding the caldera’s walls while also making that caldera larger. First, the plateau above the cliff shows multiple small cliffs and pit chains, all more or less parallel to the wall. This suggests that the plateau is over time breaking apart and falling into that caldera. Think of it as an avalanche in slow motion, with the upper plateau separating into chunks as sections slowly tilt down toward eventual collapse. As these chunks separate, they cause cracks to form in that plateau, and hence the parallel cliffs and strings of pits.

On the floor of the caldera we can see evidence of past chunks that did fall, piled up in a series terraces at the base of the wall. These are covered with the soft dust that dominates Martian geology. That soft dust also apparently comprises much of the wall’s materials, and almost acts like a liquid as it periodically flows down the wall, producing the chutes at the top of the wall.

The weak Martian gravity here is an important factor that we on Earth have difficulty understanding. It allows for a much steeper terrain, that also allows structurally weaker materials to hold together that would be impossible on Earth.This image gives a taste of this alien geology, on a large scale.

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