Tag: glaciers

What a Martian impact looks like on a sheet of slushy ice

11:00 am

Overview map

What a Martian impact looks like on a sheet of ice
Click for full image.

My headline is a bit of a guess, but it is an educated guess for today’s cool image. The photo to the right, cropped, reduced, and sharpened to post here, was taken on October 30, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The location, as indicated by the white dot in the overview map above, puts this impact in a relatively flat area of Deuteronilus Mensae, the westernmost chaos region of the 2,000 mile long mid-latitude strip I call glacier country.

In other words, there is likely a lot of near surface ice here, as this impact makes very plain. If you imagine dropping a pebble into a thick layer of soft ice cream, you might get a crater reminiscent of this. I use for comparison ice cream on Earth because the lighter Martian gravity probably makes Martian ice softer and more slushy.

As I have said many times before, Mars is strange, Mars is mysterious, and above all Mars is alien.

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Computer model: Glaciers move slower in Mars’ gravity

10:00 am

Using a computer model that compared glacier flows on Earth and Mars, scientists have concluded that past glaciers on Mars flowed more slowly than on Earth, and produced different types of erosion features that might explain the red planet’s many riverlike geological features.

The new study modeled how Mars’ low gravity would affect the feedback between how fast an ice sheet slides and how water drains below the ice, finding under-ice channels would be likely to form and persist. Fast water drainage would increase friction at the interface of rock and ice. This means ice sheets on Mars likely moved, and eroded the ground under them, at exceedingly slow rates, even when water accumulated under the ice, the authors said.

From the paper [pdf]:

We show quantitatively that the lower surface gravity on Mars should alter the behavior of wet-based ice masses by modifying the subglacial drainage system, making efficient, channelized drainage beneath Martian ice both more likely to form and more resilient to closure. Using as an example the case of the ancient southern circumpolar ice sheet, we demonstrate that the expected finger-print of wet-based Martian ice sheets is networks of subglacial channels and eskers, consistent with the occur-rence of valley networks and inverted ridges found on the Martian highlands.

This paper confirms the sense I have gotten from the planetary community about glaciers on Mars, that it could be the flow of glaciers that formed its many meandering canyons, not liquid water. The case however is not yet proven, as this is only a computer model.

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New paper: Glaciers on Mars could have been extensive, despite the lack of expected subsequent landforms

12:18 pm

glacial drainage patterns as expected on Mars
Click for full figure.

According to a new paper published this week, scientists now posit that glaciation could have been much more extensive in the geological history of Mars than presently believed, despite the lack of the expected subsequent landforms as seen on Earth.

From the abstract:

The lack of evidence for large-scale glacial landscapes on Mars has led to the belief that ancient glaciations had to be frozen to the ground. Here we propose that the fingerprints of Martian wet-based glaciation should be the remnants of the ice sheet drainage system instead of landforms generally associated with terrestrial ice sheets. We use the terrestrial glacial hydrology framework to interrogate how the Martian surface gravity affects glacial hydrology, ice sliding, and glacial erosion. …[W]e compare the theoretical behavior of identical ice sheets on Mars and Earth and show that, whereas on Earth glacial drainage is predominantly inefficient, enhancing ice sliding and erosion, on Mars the lower gravity favors the formation of efficient subglacial drainage. The apparent lack of large-scale glacial fingerprints on Mars, such as drumlins or lineations, is to be expected. [emphasis mine]

In other words, on Earth the higher gravity causes glaciers and ice sheets to slide, with the liquid water at the base acting as a lubricant. On Mars, the lower gravity slows that slide, so that the water at the glacier’s base drains away instead, causing erosion and the formation of a drainage pattern in the ground beneath the glacier or ice sheet.

The image above, from figure 1 of the paper, shows on the left a graphic of the two types of drainage patterns expected, and on the right two examples found on Earth (D1: Devon Island; D2: Northwest Territories). Orbiter images of Mars have found variations of these types of drainage patterns in numerous places in Mars’ mid-latitude glacial bands, as shown below.
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Monitoring one glacier flowing off a mesa in Mars’ glacier country

1:28 pm

Vicous glacial flow on Mars
Click for full image.

Today’s cool image takes us back to the mesa in Mars’ glacier country that first clued me in on the prevalence of ice in the Martian mid-latitudes. The photo to the right, rotated, cropped, and reduced to post here, was taken on November 13, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a viscous flow coming down from a hollow on that mesa’s southern wall.

The new image has likely been taken to see if anything has changed since the previous image was taken in 2014. Based on the resolution published at the MRO website, nothing seems to have changed, though with more sophisticated software higher resolution versions of the images are available that might show some changes.

In my first post about Mars’ glacier country in December 2019, this flow was one of four that I featured coming off this same 30-mile wide mesa, as shown by the first overview map below.
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Mars: Glaciers on top of glaciers on top of glaciers

1:16 pm

Overview map
Mars’ glacier country.

glaciers on top of glaciers on top of glaciers
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on December 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small patch of layered glacial features flowing in all directions. The overview map above marks its location by the red dot, at 40 degrees north latitude in the region dubbed Deuteronilus Mensae, on the western end of the 2,000 long strip from 30 to 60 degrees north latitude that I dub Mars’s glacier country because practically every image in this region shows glacial features.

What makes the glacial features in this picture so remarkable is their number, their somewhat chaotic nature, and the evidence of many layers, suggesting a cyclical process of ebb and flow over the eons.

Below I zoom into one section of this photo, showing that section at full resolution.
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Craters in the soft Martian northern lowland plains

12:25 pm

Craters in the soft Martian northern lowland plains
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Cool image time! The photo to the right, cropped and reduced to post here, was a featured image today from the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The caption, written by Carol Weitz of the Planetary Science Institute in Arizona, focused on the wind patterns created within these craters.

These impact craters in the northern middle latitudes have interesting interiors: all of them have wind-blown (aeolian) ripples.

Outside of the craters and along the crater floors, the ripples are all oriented in the same direction. However, along the walls of some of the larger craters, the ripples are situated radially away from the center, indicating the winds moving inside the larger craters can be influenced by the topography of the crater wall.

Additionally, many of the larger craters have layered mesas along their floors that are likely sedimentary deposits laid down after the craters formed but prior to the development of the aeolian ripples.

I am further intrigued by the rimless nature of these craters, as well as the lack of significant rocky debris at their edges. They all look like the bolides that created them impacted into a relatively soft surface that, rather than break up into rocks and boulders, melted, flowed, and then quickly refroze into these depressions.

The location, as always, provides us a possible explanation.
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Layered glaciers in Mars’ glacier country

3:48 pm

Layered glacier in Mars' glacier country
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Cool image time. The photo to the right, cropped and reduced to post here, was taken on August 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows two different impact craters in a glacial region dubbed Nilosyrtis Mensae, located in the northern mid-latitudes in the 2,000 mile long strip chaos terrain that I have labeled glacier country because practically every image finds them there.

The splash apron surrounding the larger crater is typical of craters in Martian regions where ice is thought to be near the surface.

What makes this picture interesting is that the glaciers appear layered. You can see evidence of this in the mounds inside both craters. Those mounds appear to represent earlier periods when there was more ice here. Since then the mounds have partly sublimated away.

You can also see evidence of layers in the material surrounding the nearby larger mounds.

The map below shows us where this image is, relative to all of glacier country as well as the rover Perseverance in Jezero Crater.
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Glaciers in the Martian south latitudes

1:12 pm

Glaciers in Mars' southern hemisphere
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Most of the glacier cool images I have posted in the past few years from the high resolution camera on Mars Reconnaissance Orbiter (MRO) have shown the obvious glacial features found in the northern hemisphere in that 2,000 mile long strip of chaos terrain at about 40 degrees latitude I dub “Glacier Country.”

Today’s glacier image to the right, cropped and reduced to post here, takes us instead to the southern hemisphere, into Hellas Basin, the death valley of Mars. The picture was taken on April 8, 2021, and in the full picture gives us a myriad of examples of glacial features. The section featured to the right focuses in on what appears to be an ice covered south facing slope, which in the southern hemisphere will get the least sunlight.

Think of the last bits of snow that refuse to melt after a big blizzard. They are always found in shadowed areas, which in the southern hemisphere would be this south-facing slope.

The overview map below shows how this location, marked by the small white rectangle, is inside Hellas Basin, at a low altitude comparable to the northern lowland plains. The feature is also a comparable latitude, 43 degrees south, to the glacier country of the north.
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Spring arrives on the northern polar cap of Mars

1:37 pm

Buzzell dunes and pedestal crater near the Martian north polar ice cap
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Cool image time! It is now spring in the northern hemisphere of Mars, and the first bits of sunlight are finally reaching its north polar ice cap. During the winter, as happens each Martian year, that polar cap of water ice gets covered by a thin mantle of dry ice no more than six feet thick. Moreover, this mantle doesn’t just cover the ice cap, it extends south as far as about 60 degrees latitude, covering the giant sea of dunes that surrounds the ice cap.

When spring comes that mantle begins sublimate away, with its base first turning to gas. When the pressure builds up enough, the gas breaks out through the frozen mantle’s weakest points, usually the crest or base of dunes or ridges, leaving behind a dark splotch caused by the material thrown up from below that contrasts with the bright translucent dry ice mantle.

Each year for the past decade scientists have been using the high resolution camera on Mars Reconnaissance Orbiter (MRO) to monitor this sublimation process. The photo above, taken on February 24, 2021 and cropped, enlarged, and brightened to post here, marks the start of this year’s monitoring program. Dubbed informally “Buzzell” by Candice Hansen of the Planetary Science Institute in Arizona, it shows dunes with a round pedestal crater just right of center. Though almost everything when this picture was taken is still covered by that dry ice mantle, in the lower left is a single splotch, the first breakout of CO2 gas that marks the beginning of the annual disappearance of this dry ice.

Last Martian year I repeatedly posted images of Buzzell to illustrate this annual process. The second image below was taken on April 4, 2019, at about the same comparable time in spring.
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Study: a Martian crater lake fed by glacial run-off

1:19 pm

Map of crater lake and run-offs
From figure 1 on the research paper.

A new study of a 33-mile-wide Martian crater in its southern cratered highlands has found evidence that a lake had once existed on the crater floor, and was fed entirely by glacial run-off in a cold climate, coming from its interior walls, not from outside the crater.

In a study published in Planetary Science Journal, a research team led by Brown Ph.D. student Ben Boatwright describes an as-yet unnamed crater with some puzzling characteristics. The crater’s floor has unmistakable geologic evidence of ancient stream beds and ponds, yet there’s no evidence of inlet channels where water could have entered the crater from outside, and no evidence of groundwater activity where it could have bubbled up from below.

So where did the water come from?

The researchers conclude that the system was likely fed by runoff from a long-lost Martian glacier. Water flowed into the crater atop the glacier, which meant it didn’t leave behind a valley as it would have had it flowed directly on the ground. The water eventually emptied into the low-lying crater floor, where it left its geological mark on the bare Martian soil.

You can read the full paper here. The crater is considered very old, which means this evidence dates from a very early Mars when the climate was very different. As the scientists note in their conclusion:
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A cracking Martian glacier?

12:21 pm

A cracking Martian glacier?
Click for entire image.

Cool image time! The photo to the right, cropped to post here, was taken on December 4, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO)

I have cropped it to show at full resolution the area that contains what the scientists apparently consider the most interesting feature in this image, which they have labeled as “pits forming lines.” These are the vertical cracks and strings of holes that can be seen in this glacier-like flow. In addition, you can see that the cracking is not just vertical, but also extends out in horizontal directions, though the widest cracks are all vertical.

The next image below, which is a lower resolution crop of the full photo, shows a wider view to provide a better picture of the glacier itself.
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Mars: Planet of many glaciers

12:08 pm

Moraines on Mars
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Today’s cool image more than simply cool, it reveals a wider picture of Mars that should be quite exciting to future colonists. The photo to the right, rotated, cropped, and reduced to post here, was taken on January 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). What drew my attention to it was the title given to this uncaptioned photo: “Moraine-Like Ridges in Nereidum Montes.”

Moraines are the debris pile pushed ahead of any glacier. The picture shows what appear to be a series of moraines, likely caused by different periods of glacier activity when the glacier was growing. It also suggests that past active periods were more active than later ones, as with each active period the moraine did not get pushed out quite as far.

The location, Nereidum Montes, intrigued me, as I am not that familiar with it. I emailed the scientist who requested the image, Dan Berman, senior scientist at the Planetary Science Institute in Arizona, and asked him for more information. He suggested I read a very recent paper he co-wrote entitled “Ice-rich landforms of the southern mid-latitudes of Mars: A case study in Nereidum Montes.” From that paper I was able to produce the map of Mars below that shows the regions on the planet where scientists now think hold the greatest concentrations of glaciers.
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Scientists: Gale Crater never had flowing surface water and was always cold

11:04 pm

The uncertainty of science: According to a new analysis of the data from Curiosity and Martian orbiters, scientists now propose that the climate in Gale Crater was never warm, but ranged from Icelandic conditions to far colder.

More importantly, the data suggests that none of chemistry there that required the presence of water was formed by fluvial processes, or flowing water. From the abstract:

We show that the geochemistry and mineralogy of most of the fine‐grained sedimentary rocks in Gale crater display first order similarities with sediments generated in climates that resemble those of present‐day Iceland, while other parts of the stratigraphy indicate even colder baseline climate conditions. None of the lithologies examined at Gale crater resemble fluvial sediments or weathering profiles from warm (temperate to tropical) terrestrial climates. [emphasis mine]

As must be repeated, the mineralogy found by Curiosity points to the presence of water once in Gale Crater, now gone. The initial assumption has always been that this water must have been liquid, as found on Earth. This new research is noting that the conditions show little evidence that liquid water ever existed, but was instead held in frozen lakes and glaciers.

In the coming years I think we are going to learn a lot about the glaciers and ice on Mars, both past and present, and how they reshaped Mars in ways that are alien to processes found on Earth.

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Antarctica data adds weight to hypothesis that glaciers shaped Mars

10:01 am

New data from an Antarctica ice core strengthens the hypothesis that the flow of glaciers, not liquid water, helped shape the meandering canyons on Mars.

The data was the discovery of the mineral jarosite deep within the south pole ice-cap. Jarosite needs water to form. Previously it was generally believed it formed in conjunction with liquid flowing water. On Mars, which appears to have lots of jarosite, scientists have struggled for decades to figure out how enough liquid water could have existed on the surface of Mars to produce it.

The discovery of jarosite deep inside the Antarctic ice cap now suggests that it can form buried in ice, not liquid water. According to the scientists,

the jarosite was born within massive ice deposits that might have blanketed [Mars] billions of years ago. As ice sheets grew over time, dust would have accumulated within the ice—and may have been transformed into jarosite within slushy pockets between ice crystals.

From the paper’s conclusions:

The occurrence of jarosite in TALDICE [in Antarctica] supports the ice-weathering model for the formation of Martian jarosite within large ice-dust deposits. The environment inside the Talos Dome ice [in Antarctica] is isolated from the Earth atmosphere and its conditions, including pressure, temperature, pH and chemistry, provides a suitable analogue for similar Martian settings. Dust deposited at Talos Dome is also similar to Martian atmospheric dust, being both mostly basaltic. Within thick ice deposits it is likely that the environment would be similar at Talos Dome and under Mars-like conditions since both settings would contain at cryogenic temperatures basaltic dust and volcanogenic and biogenic (for Antarctic only) sulfur-rich aerosols. … Considering this context, it is reasonable that the formation of jarosite on Mars involves the interaction between brines and mineral dust in deep ice, as observed in TALDICE. This mechanism for Martian jarosite precipitation is paradigm changing and strongly challenges assumptions that the mineral formed in playa settings.

Playa settings are places where there is standing liquid water, slowing drying away.

This result is another piece of evidence that ice and glaciers were the cause of the Martian terrain that to Earth eyes for decades was thought to have formed by flowing water. It also continues what appears to be a major shift on-going in the planetary science community, from the idea of liquid water on Mars to that of a planet dominated by glacial and ice processes.

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More evidence Mars’s glaciers formed across many ice ages

11:26 am

The uncertainty of science: New research using the boulders found on the top of Martian glaciers has now strengthened the evidence that Mars must have undergone many previous ice age cycles going back as much as 800 million years, with those glaciers waxing and waning during each cycle.

This new data helps map the cycles earlier than 20 million years ago, which have been difficult to map out based solely on the orbital data available from Earth and from Mars orbit. The results suggest that before then there were from six to twenty additional cycles during the last 300 to 800 million years.

These numbers are decidedly uncertain. It is likely that there were many more cycles, as suggested by the many layers seen at the edges of the north and south polar ice caps.

Be aware as well that if you read the press release you should know that it falsely implies that this research is the first to map out these ice age cycles. This is not true. All this research has done is provide more evidence for cycles prior to 20 million years ago, cycles that scientists have long believed must have happened based on other data.

In the end, for us to map out the full climate history of Mars will require numerous ice core samples at the planet’s poles, something that will not be possible until people are living and working on Mars routinely.

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Sagging cliffs on Mars

11:20 am

Sagging escarpment on Mars
Click for full image.

Cool image time! On Mars things change, but not like on Earth because the atmosphere is not as thick and there is no flowing water. The photo to the right, rotated, cropped, reduced, and annotated to post here, gives a good example of that slow change. The image was taken on August 29, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows the high escarpment that in this one place separates the planet’s southern cratered highlands from the transition zone down to northern lowland plains.

In this spot that escarpment, approximately 4,000 feet high, shows signs of avalanches and sagging. In the upper steep section, I point to what looks like a dust avalanche that wiped the slope clear of rough terrain as it rolled downhill. At the bottom of the cliff a large section has separated away. Since this cliff is located at 28 degrees north latitude and is in the midst of the chaos terrain regions I like to dub glacier country, it is very possible that this large section is actually buried glacial ice that in shifting down slope cracked, separating the lower section from the upper.

This particular location is east of an area dubbed Nilosyrtis Mensae (where there is a lot of evidence of glaciers and frozen ice), and about 650 miles north of Jezero Crater, where the rover Perseverance will land on February 18, 2021.

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An ice-covered mountain on Mars?

2:00 pm

Ice-covered mountain on Mars?
Click for full image.

Grinnell Crater in Glacier National Park in 2017

Today’s cool image, taken on July 1, 2020 by the high resolution camera on Mars Reconnaissance Orbiter, is of a mound-like mountain on Mars that to all intents and purposes appears covered by glacial ice, some eroded, some not.

The image to the right, rotated, cropped, and reduced to post here, shows this mound. Both the flow coming down from the mountain top down the north slope as well as the flow in the north that appears to begin in a small crater suggest glacial features.

Even more convincing are what appear to be patches of glacial ice on the southern slopes, resembling the kind of glacial patches you see everywhere in Glacial National Park. The second photo to the right, taken by me on our visit to Glacier National Park in 2017, shows similar patches hugging the mountainside at Grinnell Glacier.

This Martian mountain is located in the southern hemisphere inside Hellas Basin on its eastern interior rim. (See the overview map below, with the location of this photo the small white box south of Harmakhis Valles.) Thus, you would expect the north-facing slope to get more sunlight (and more heat) than the south-facing slopes. Yet, from this image there appears to be greater erosion on the south-facing slopes. A puzzle indeed.
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More glaciers and eroding gullies on Mars

2:51 pm

Crater with gullies and glacial fill
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Cool image time! The photo to the right, cropped and reduced to post here, shows the interior south-facing rim of a small crater in the southern cratered highlands of Mars. Taken on May 30, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the image release is merely labeled “Gullied Slope”. The photo was taken as part of regular monitoring of these gullies since 2011 to see if they change from season to season. The 2011 image was captioned by planetary scientist Alfred McEwen, who wrote the following about the gullies:

These are erosional features with depositional fans. Some of the gully fans have a bluish color: these are probably quite recent deposits, less than a few tens of years old.

Since they were considered so very young, it makes great sense to look at them frequently. In making a quick comparison between the 2011 and 2020 images however I could not spot any changes, but that might be because the versions I downloaded are not at the fullest resolution.

This crater, at 39 degrees south latitude, is also worthwhile because its floor appears covered with glacial material, what scientists have dubbed concentric crater fill. As McEwen noted in his 2011 caption,

On the floor of the crater (bottom of this image) are ridges that likely formed from the flow of ice, perhaps a few million years ago.

Those glaciers, generally protected by thin layers of dust and debris, are considered inactive at this time in Martian geological history. The many ridges however hint at the many many cycles in the Martian climate, fluctuating between periods when these mid-latitude glaciers were growing while the polar ice caps were shrinking, and periods when the mid-latitude glaciers were shrinking while the polar ice caps were growing.

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Filled and distorted craters on Mars

9:12 pm

A very distorted and filled crater on Mars
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Cool image time! The photo to the right, rotated and cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 25, 2020. The entire image was dubbed “Cluster of Filled Craters”, but I decided to highlight the crater of the cluster that was most strangely distorted of them all. The material that fills all the craters in the full image is almost certainly buried ice and is dubbed concentric crater fill by scientists.

This crater is located in the northern lowland plains the mid-latitudes between 30 and 60 degrees, where planetary scientists have found ample evidence of many such filled craters and glaciers.

Not only does the crater’s interior seemed filled with glacial material, its distorted rim suggests that it has been reshaped by glacial activity that might have covered it entirely over the eons as the mid-latitude glaciers of Mars waxed and waned with the extreme shifts that happen regularly to Mars’ rotational tilt. Moreover, there is strong evidence that in these lowland northern plains an underground ice table exists close to the surface, allowing for more distortion over time.

The overview map below provides some location context.
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Glacier country on Mars

12:47 pm

Glacial flow in Protonilus Mensae
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on May 24, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and provides a wonderful example of the kind of evidence of buried glaciers found extensively in the mid-latitudes of Mars.

This particular region, called Protonilus Mensae, is a region of chaos terrain at the transition zone between the southern cratered highlands and the northern lowland plains. I have featured a number of cool images in Protonilus, all of which show some form of buried glacial flow, now inactive.

The last cool image above was one that the MRO science team had picked to illustrate how to spot a glacier on Mars.

In this particular image are several obvious glacier features. First, we can see a series of moraines at the foot of each glacier in the photo, each moraine indicating the farthest extent of the glacier when it was active and growing. It also appears that there are two major layers of buried ice, the younger-smaller layer near the image’s bottom and sitting on top of a larger more extensive glacier flow sheet. This suggests that there was more ice in the past here, and with each succeeding ice age the glaciers grew less extensive.

Second, at the edges of the flows can be seen parallel ridges, suggestive also of repeated flows, each pushing to the side a new layer of debris.

Third, the interior of the glacier has parallel fractures in many places, similar to what is seen on Earth glaciers.

Protonilus Mensae, as well as the neighboring chaos regions Deuteronilus to the west and Nilosyrtis to the east, could very well be called Mars’ glacier country. Do a search on Behind the Black for all three regions and you will come up with numerous images showing glacial features.

Below is an overview of Protonilus, the red box showing the location of this image. Also highlighted by number are the locations of the three features previously posted and listed above.
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Martian eroding ridges amid brain terrain

12:09 pm

Brain terrain and bisected ridges on Mars
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Today’s very cool image is cool because of how inexplicable it is. To the right, cropped to post here, is a photo taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) of an area of what they call “Ribbed Terrain and Brain Terrain”.

I call it baffling.

Nor am I alone. At the moment the processes that create brain terrain (the undulations between the ridges) remain a complete mystery. There are theories, all relating to ice sublimating into gas, but none really explains the overall look of this terrain.

Making this geology even more baffling are the larger ridges surrounding the brain terrain, all of which appear to have depressions along their crests. Here too some form of sublimation process appears involved, but the details remain somewhat mysterious.
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The edge of an eroded buried Martian glacier

12:55 pm

The edge of an eroded buried Maritian glacier
Click for full resolution image.

Overview

Cool image time! The image to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on April 6, 2020.

The image shows the dying edge of a debris flow coming down from a mesa, the edge of which can be seen as the dark slopes in the upper left. The white arrows point up slope. It is located in the chaos terrain of a mid-latitude region called Deuteronilus Mensae, in the transition zone between the southern highlands and northern lowlands, where many such glacial-like features are found. I featured a similar nearby glacial edge only two months ago, where the image showed the glacier’s break up and collapse at its edge.

Here, the debris flow isn’t breaking up so much as crumbling away, its edge a line of meandering depressions, with the uphill slope covered with many knobs and tiny depressions, reminiscent to me of the many features I see in caves, where the downward flow of water shapes and erodes everything to form cups and holes and knobs, all the same size. If you click on the full resolution image and zoom into that debris slope and then compare it with the linked cave formation photo, you will see the resemblance.

We are almost certainly looking at a buried inactive glacial flow coming off that mesa, though it appears to be eroding at its foot. The overview image to the right shows the context, with the red dots indicating this image as well as similar features in adjacent mensae regions (featured in the linked images above). While the chaotic and rough terrain found along this transition zone does not make them good first settlement sites, the ample evidence of vast reservoirs of buried ice, combined with a variety of topography, will likely someday make this good real estate for those living on Mars.

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The icy Phlegra Mountains: Mars’ future second city

1:35 pm

Icy glaciers in the Phlegra Mountains of Mars
Click for full image.

About a thousand miles to the west of the candidate landing site for SpaceX’s Starship spacecraft rises a massive mountain wall dubbed the Phlegra Mountains, rising as much as 11,000 feet above the adjacent lowland northern plains.

Phlegra Montes (its official name) is of special interest because of its apparent icy nature. Here practically every photograph taken by any orbiter appears to show immense glacial flows of some kind, with some glaciers coming down canyons and hollows [#1], some filling craters [#2], some forming wide aprons [#3] at the base of mountains and even at the mountains’ highest peaks [#4], and some filling the flats [#5] beyond the mountain foothills.

And then there are the images that show almost all these types of glaciers, plus others [#6]. Today’s cool image above is an example of this. In this one photo we can see filled craters, aprons below peaks, and flows moving down canyons. It is as if a thick layer of ice has partly buried everything up the highest elevations.

None of this has gone unnoticed by scientists. For the past decade they have repeatedly published papers noting these features and their icy appearance, concluding that the Phlegra Mountains are home to ample buried ice. SpaceX even had one image taken here [#3] as a candidate landing site for Starship, though this is clearly not their primary choice at this time.

The map below gives an overview of the mountains, their relationship to the Starship landing site, and the location by number of the images listed above.
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Large glacier-filled crater/depression on Mars?

12:31 pm

Glacier-filled depression?
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Cool image time! The photograph on the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on December 21, 2019. It shows the eastern half of the floor and interior rim of a large squarish-shaped crater or depression in what seems to be an unnamed region of chaos terrain located in the transition zone between the Martian southern highlands and the northern lowland plains.

The floor of this depression has many of the features that indicate the presence of a buried ice glacier, including flow features on the depression floor, linear parallel grooves, and repeating moraine features at the slope base. In fact, all these features give the strong impression that this crater is ice-filled, to an unknown depth.

Chaos terrain, a jumble of mesas cut by straight canyons, are generally found in this transition zone, and could be an erosion feature produced by the intermittent ocean that some believe once existed in the northern lowlands. Whether or not an ocean lapped against these mesas and created them, this chaos terrain is believed to have been caused by some form of erosion, either wind, water, or ice.

Wide context view

The location is of this chaos terrain in that transition zone is illustrated by the context map to the right. It sits on the edge of the vast Utopia Basin, one of the largest and deepest northern lowland plains. It also sits several hundred miles due north of the planned landing site of the Mars2020 rover in Jezero Crater. There is a lot of chaos terrain in this region, with lots of evidence of buried glaciers flowing off the sides of mesas.

Today’s image, with its numerous features suggesting the presence of a buried glacier filling the depression, reinforces this evidence.

Closer context view, showing the chaos terrain region

What impresses me most about this particular depression — should it be ice-filled — is its size. I estimate from the scale of the image that the depression is about six miles across, somewhat comparable though slightly smaller than the width of the Grand Canyon. And yet, unlike the Canyon it appears to have a wide flat floor across its entire width. The second context map to the right zooms in on this chaos region to show how relatively large the depression is. It would not be hard to spot it from orbit. We don’t know the depth, but even if relatively shallow this depression still holds a heck of a lot of water ice.

While the depression appears like a crater in lower resolution wider photographs, higher resolution images suggest it is not round but squarish. Why is not clear, and unfortunately MRO’s high resolution camera has taken no other images of it. This image was also one of their terrain sample photographs, taken not because of any specific research request, but because they need to use the camera regularly to maintain its temperature. This location, having few previous images, fit this schedule and made sense photographing.

Thus, no one appears to be specifically studying this location, making it a ripe subject for some postdoc student who wants to put their name on some Martian geology.

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Remnant moraine on Mars

12:30 pm

Remnant moraine on Mars
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Cool image time! Using both Martian orbiters and rovers scientists are increasingly convinced that Mars has lots of buried glaciers in its mid-latitudes. These glaciers are presently either inactive or shrinking, their water ice sublimating away as gas, either escaping into space or transporting to the colder poles.

The image to the right, cropped and reduced to post here, shows some apparent proof of this process. Taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on December 23, 2019, it shows a weird meandering ridge crossing the floor of a crater. The north and south parts of the crater rim are just beyond the cropped image, so that the gullied slope in the image’s lower left is actually a slope coming down from that rim.

My first reaction upon seeing this image was how much that ridge reminded me of the strange rimstone dams you often find on cave floors, formed when calcite in the water condenses out at the edge of the pond and begins to build up a dam over time.

This Martian ridge was certainly not formed by this process. To get a more accurate explanation, I contacted Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who had requested this image. He explained:
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Further explorations at candidate Starship Mars landing site

4:02 pm

Beginning of Possible Glacial Unit near candidate Starship landing sites
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Close-up on exposed lower layer

Cool image time! Even though it appears that SpaceX has completed its first round of images of its candidate landing sites surrounding the Erebus Montes mountains in the Arcadia Planitia plains in the Martian northern lowlands, this does not mean that other planetary scientists are not asking for more images of this region, for their own scientific research.

The photograph on the right, cropped and reduced to post here, was released in the early November image download from the high resolution camera of Mars Reconnaissance Orbiter (MRO). Uncaptioned but dubbed “Beginning of Possible Glacial Unit,” it shows what appears at first glance to be a relatively featureless area south of Erebus Montes, out in the flat plains.

A closer look suggests otherwise. For one, the full image shows darker and lighter areas. The close-up to the right, its location indicated by the white box in the wider image above, also shows several intriguing depressions that appear to be revealing a knobby lower layer. In fact, in the full image it appears that the darker areas are areas where material has covered that knobby lower layer. Where it is bright the ground resembles the floors of these depressions, knobby and complex.

I do not know why they label this the “beginning” of a glacial unit. What I do know is that the research of this region has consistently found evidence of a lot of buried ice. To quote Donna Viola of the University of Arizona noted, “I think you could dig anywhere to get your water ice.” The knobby features to me suggest a surface that is showing signs of sublimation, where the exposed ice is slowly eroding. Think of what happens to a block of ice when you spray warm water on it. As it melts it leaves behind just these kinds of strange formations.

Overview of all MRO images at Starship candidate landing site

The red box in the map on the right shows the location of this photograph relative to the other images taken for SpaceX. The white boxes are the company’s images taken for Starship. The black boxes are the images it obtained in 2017 when it was thinking of sending a Dragon capsule to Mars.

This map does not show all images taken by MRO’s high resolution camera in this area, but the coverage is very scattered, with many gaps. Over time I suspect these gaps will be filled more quickly than other northern plain regions, because the scientists know that SpaceX has an interest in this area. That interest means there is an increased chance that a mission will fly here in the relatively near future, which in turn is going to generate more scientific interest as well.

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Mars Express confirms ancient glaciers in northern Martian mid-latitudes

9:46 pm

Perspective view of Deuteronilus Mensae
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The European Space Agency’s orbiter Mars Express has confirmed the presence of large fractured ice sheets suggestive of buried and ancient glaciers. These ice sheets are within one region on Mars located in the mid-latitudes where many such glacial features have been found. They are also in the transition zone between the northern lowlands and the southern highlands.

This landscape shows clear and widespread signs of significant, lasting erosion. As is common with fretted terrain, it contains a mix of cliffs, canyons, scarps, steep-sided and flat-topped mounds (mesa), furrows, fractured ridges and more, a selection of which can be seen dotted across the frame.

These features were created as flowing material dissected the area, cutting through the existing landscape and carving out a web of winding channels. In the case of Deuteronilus Mensae, flowing ice is the most likely culprit. Scientists believe that this terrain has experienced extensive past glacial activity across numerous martian epochs.

It is thought that glaciers slowly but surely ate away at the plains and plateaus that once covered this region, leaving only a scattering of steep, flat, isolated mounds of rock in their wake.

Smooth deposits cover the floor itself, some marked with flow patterns from material slowly moving downhill – a mix of ice and accumulated debris that came together to form and feed viscous, moving flows of mass somewhat akin to a landslide or mudflow here on Earth.

Studies of this region by NASA’s Mars Reconnaissance Orbiter [MRO] have shown that most of the features seen here do indeed contain high levels of water ice. Estimates place the ice content of some glacial features in the region at up to 90%. This suggests that, rather than hosting individual or occasional icy pockets and glaciers, Deuteronilus Mensae may actually represent the remnants of an old regional ice sheet. This ice sheet may once have covered the entire area, lying atop the plateaus and plains. As the martian climate changed this ice began to shift around and disappear, slowly revealing the rock beneath.

Overall, the data coming from both Mars Express and MRO increasingly suggests that there is a lot of buried glacial ice in the mid-latitudes. Mars might be a desert, but it is increasingly beginning to look like much of the planet is a desert like Antarctica, not the Sahara.

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Mid-latitude Martian glacier?

10:01 am

Glacier on Mars?
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Cool image time! I have posted a lot of Mars photographs in the past few months showing possible glaciers in the mid-latitudes of Mars, where scientists think they have identified a lot of such features. Today is another, but unlike many of the previous examples, this particular feature more closely resembles a typical Earth glacier than almost any I have so far posted.

Based on the image’s title, “Lineated Valley Fill in Northern Mid-Latitudes,” given by the science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO), I suspect that it remains unproven that these are features of buried glacial ice. Thus, they use a more vague descriptive term, lineated, to avoid pre-judging what these features are.

Nonetheless, a glacier is sure what this lineated valley fill looks like. See for example the Concordia confluence of two glaciers in the Karakoram Mountains of Pakistan, near the world’s second highest mountain, K2. Though obviously not the same, you can see many similarities between this Martian feature and Concordia.

MRO has taken only three photographs of this particular valley, with one image useless because it was taken during a dust storm. Yet, the other good image, farther downstream in this valley, shows very similar features.

The valley itself is formed from chaos terrain, located in the transition zone between the southern cratered highlands and the flat northern lowlands where a possible intermittent ocean might have once existed. Thus, for buried ice to be here is quite possible.

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Ancient glacier flows on Mars

3:17 pm

Ancient glacial flow in Euripus Mons
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Cool image time! In the recent download of images from the high resolution camera of Mars Reconnaissance Orbiter (MRO), I found the image on the right, rotated, cropped, and reduced to post here. It shows an example of the many glacial flows coming off of the slopes of Euripus Mons, the sixteenth highest mountain on Mars.

We know these are glaciers because data from SHARAD, the ground-penetrating radar instrument MRO, has found significant clean ice below the surface, protected by a debris layer that insulates it. As planetary scientist Alfred McEwen of the Lunar & Planetary Laboratory in Arizona explained to me in a phone interview yesterday,

These are remnant glaciers. Basically they form like glaciers form. They are not active or if they are they are moving so extremely slowly that effectively they are not active.

If you look close, you can see that this particular glacier was made up of multiple flows, with the heads or moraines of each piled up where each flow ended. In addition, this overall glacier appears to have been a major conduit off the mountain, following a gap between more resistant ridges to the east and west.

The sequence of moraines suggest that when the glacier was active, it experienced alternating periods of growth and retreat, with the growth periods being shorter and shorter with time. As a result each new moraine was pushed less distance down the mountain as the previous one.

Euripus Mons is interesting in that it has a very large and distinct apron of material surrounding it, as shown in the overview image below.
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Weird glacial features in Martian crater

1:47 pm

weird glacial feature in crater on Mars
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Cool image time! In reviewing today’s October release of new images from the high resolution camera of Mars Reconnaissance Orbiter (MRO), I came across the strange geology shown in the image to the right, rotated, cropped, and reduced to post here.

The uncaptioned image calls these “glacial features within crater.” The crater is located at 35 degrees north latitude in Arabia Terra, one of the more extensive regions of the transition zone between the northern lowlands and the southern highlands. It is also located within the northern band from 30 to 60 degrees latitude where most of the buried Martian glaciers are found.

The most abundant type of buried glaciers are called concentric crater fill (CCF) because they are found inside craters, and often show decay in a concentric manner. This weird feature likely falls into that category, though I would hardly call these glacier features concentric.

I’m not even sure if this is an impact crater. If it is, its rim has been heavily obscured, making it look instead like an irregular depression with one outlet to the south. In fact, I suspect it is possibly one of the lakes that scientists believe pepper this part of Arabia Terra and might have contained liquid water two to three billion years ago. That water would have later frozen, and possibly become covered by dust and debris to protect it.

According to present theories, Mars is presently in a period where its mid-latitude glaciers are shrinking, the water sublimating away and being transported back to its poles. The weird formations here suggest this process. Imagine what happens when you spray warm water on a big block of ice. It dissolves, but randomly to form weird shapes.

In this case the glacier is shrinking randomly where the ice has gotten exposed. In the thin Martian atmosphere, it transitions directly from a solid to a gas, sublimating into the atmosphere to leave these inexplicable shapes.

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