Tag: Mars

Another model proposed for explaining flowing liquid water in the distant Martian past

2:35 pm

New model for explaining flowing water on Mars
Click for full resolution graphic.

A new model has now been proposed for explaining how liquid water could have once flowed on Mars and created the many channels and river-like features geologists see today.

This new theory posits that the carbon dioxide in the atmosphere, once thicker, fell as snow to bury water ice on the surface near the poles, where that ice then melted from pressure and heat from below to flow underground and then out into lower latitudes.

The paper, led by Planetary Science Institute Research Scientist Peter Buhler, describes how 3.6 billion years ago, carbon dioxide froze out of Mars’ atmosphere and deposited on top of a water ice sheet at the poles, insulating heat emanating from Mars’ interior and increasing the pressure on the ice. This caused roughly half of Mars’ total water inventory to melt and flow across its surface without the need for climatic warming.

The graphic to the right is figure 1 from Buhler’s paper. It shows this process in the south pole, flowing north through Argyre Basin and along various now meandering channels to eventually flow out into the northern lowland plains. In every case Buhler’s model posits the water flowed in “ice-covered rivers” or “ice-covered lakes”, the ice protecting the water so that it could flow as a liquid.

This model confirms once again my impression that the Mars planetary community is increasingly considering glaciers and ice as a major past factor in shaping the planet we see today. This model suggests liquid water under ice, but it still remains possible that ice alone could have done the job.

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A somewhat typical but strange crater in Mars’ Death Valley

1:57 pm

A somewhat typical crater in Mars' death valley
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 29, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team labels the primary feature in this picture as “ridges,” but what I see is a strange crater that at first glance appears to be impact-caused, but at closer inspection might be something else entirely.

This unnamed crater is about one mile wide. It is only about fifty feet deep, but sits above the surround landscape by about 200 feet. That high position suggests strongly that this crater was not formed by an impact by is instead a caldera from some sort of volcanic activity, with the splash apron around it simply examples of past magma flows erupting from within.

The ridges inside the crater might be glacial debris, as this location is at 35 degrees south latitude, making near surface ice possible.
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Weird ring-mounds in one of Mars’ largest craters

3:03 pm

Weird ring mounds on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 16, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labels these strange features “ring-mound landforms,” a term that has been used to describe [pdf] only vaguely similar features previously found in the Athabasca flood lava plain almost on the other side of Mars. That paper suggested that those ring mounds formed on the “thin, brittle crust of an active fluid flow” created by an explosive event. Since Athabasca is considered Mars’s most recent major flood lava event, the fluid was likely lava, which on Mars flows more quickly and thinly in the lower gravity.

Thus, in Athabasca the ring-mounds formed when a pimple of molten lava from below popped the surface.

But what about the ring mounds in the picture to the right?
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“What the heck?” lava on Mars

1:47 pm


Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 19, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely snapped not for any specific research project, but to fill a gap in the camera schedule in order to maintain its proper temperature.

When the science team does this they try to pick interesting locations. Sometimes the picture is relatively boring. Sometimes, like the picture to the right, it reveals weird geology that is somewhat difficult to explain. The picture covers the transition from the smooth featureless plain to the north, and the twisting and complex ridges to the south, all of which are less than a few feet high.

Note the gaps. The downgrade here is to the west, and the gaps appear to vaguely indicate places where flows had occurred.
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Perseverance looks across Jezero Crater from on high

11:11 am

Panorama of Jezero Crater
Click for full resolution annotated image. Click here for unannotated full resolution image.

Cool image time! The panorama above, cropped, reduced, and sharpened to post here, was assembled from 44 pictures taken by the rover Perseverance on September 27, 2024 as it began its climb up the rim of Jezero Crater. If you click on it you can see the full resolution image that is also annotated to identify features within the crater as well as places where Perseverance has traveled.

The overview map below, with the blue dot showing the rover’s location when this panorama was taken. The yellow lines indicate the area covered by the panorama, with the arrow indicating the direction.

Overview map
Click for interactive map.

According to the information at the link, the rover has been experiencing some slippery sandy ground as it has been climbing.
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A pointy mesa once washed by theorized Martian ocean

11:09 am

A pointy mesa on Mars
Click for original image.

Today’s cool image returns to the same region yesterday’s cool image visited. The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 21, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was clearly taken to get a close look at this unusual pointy mesa.

MRO elevation data says this mesa is about 800 feet height. The color difference between the north and south flanks suggests the accumulated presence of dust on the north, suggesting the prevailing winds here come from the northeast and blow to the southwest. This conclusion is reinforced by the dark accumulated dust found in the southwest quadrants of all the crater floors in the full image. The wind blows this dust into the craters, where it gets trapped against the southwest crater wall.

Note the mesa’s wide base, with one crater partly eaten away on its eastern edge. The overall shape of this base suggests that it was carved by some flow coming from the southwest, as indicated by the arrow.
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The obvious visual evidence for assuming Mars once had catastrophic floods

12:03 pm

The obvious visual evidence of past catastropic floods on Mars
Click for original image.

Since the first comprehensive orbital data of Mars was sent back in the early 1970s by Mariner 9, scientists have generally concluded that many of the features seen at the eastern end of the giant Valles Marineris canyon were caused by one or several catastrophic floods.

The picture to the right, rotated, cropped, and reduced to post here and taken on July 26, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), provides a good example of why the scientists have come to that conclusion. It shows what the camera team labels a “streamline feature surrounding crater.” I have added the arrows to indicate the presumed direction of flow. The flow went around this 2.5-mile-wide unnamed crater because the impact had compacted it, making it resistent to erosion. The flow however was strong and large enough to wash away the plateau on which the crater sits, as well as cutting into the crater’s southwest rim. In addition, the rim on the southeast was also cut through at some point, this time from what might have been flow eddies as the flood pushed past.

Hence, the theory of catastrophic floods.

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Perseverance’s future increasingly rocky road

11:51 am

Perseverance's uphill route
Click for original image.

Though nothing in any image so far from the Mars rover Perseverance matches the rocky terrain that the rover Curiosity has been traversing for the past two years as it climbs Mount Sharp in Gale Crater, as Perseverance has been climbing up the rim of Jezero Crater in the past few weeks it is beginning to get a hint of a future rougher road.

The photo to the right, cropped, reduced, and sharpened to post here and taken on October 20, 2024 by one of the rover’s high resolution cameras, is a good example. It looks uphill in the direction that the rover will travel. Note how as you go higher the ground appears to be more strewn with rocks and boulders. Another image, taken the same day by the rover’s high resolution camera, shows a close-up of an even more boulder-covered landscape.
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A different kind of chaos on Mars

2:25 pm

A different kind of chaos on Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 23, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I had originally chosen to feature a different picture of this spot, taken on August 1, 2024 in order to create a stereo pair, but this week the camera team featured this first photo, providing a caption.

This disrupted surface is characterized by a collection of rounded to flat-topped mounds of various sizes connected by narrow flat floors, typical of the aptly named “chaotic terrain” on Mars.

What could have caused this flat surface to break into pieces? You might imagine that a flat surface could be broken up if it was inflated or collapsed. One hypothesis is that large amounts of water were released from deep below the ground to cause the surface break up.

Normally on Mars, especially in the mid-latitudes, chaotic terrain is associated with glacial activity, suggesting that glaciers over time erode valleys along random criss-crossing fault lines to create the mesas and canyons. This patch of chaotic terrain however suggests a different formation process.
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NASA assembles two new panels to review its Mars Sample Return mission plans

10:38 am

NASA yesterday announced that it has assembled two new panels to review its Mars Sample Return mission plans, dubbed the strategy review and the analysis team, to be done in conjunction with the proposals the agency has already received from the private sector.

The team’s report is anticipated by the end of 2024 and will examine options for a complete mission design, which may be a composite of multiple studied design elements. The team will not recommend specific acquisition strategies or partners.

The strategy review team has been chartered under a task to the Cornell Technical Services contract. The team may request input from a NASA analysis team that consists of government employees and expert consultants.

The analysis team also will provide programmatic input such as a cost and schedule assessment of the architecture recommended by the strategy review team.

The first panel contains a mixture of NASA officials and scientists, while the second is mostly made up of NASA managers.

Whatever these panels decide, it is very clear that major changes are required to this project in order to get the Perseverance core samples on Mars back to Earth within a reasonable amount of time and at an acceptable cost. The present project design is chaotic, confused, and running significantly overbudget and behind schedule, with no indication anything will change in the near future.

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Spring etch-a-sketch near the Martian south pole

1:06 pm

Spring etch-a-sketch near the Martian south pole
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 28, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely snapped not as part of any specific research project but to fill a gap in the camera’s schedule so as to maintain its proper temperature.

The camera team tries to find interesting geology when they do this, and are frequently successful. In this case the image shows some truly alien Martian terrain at 77 degrees south latitude, about 475 miles from the south pole.

What are we looking at? I promise you it isn’t the iron filings found inside an Etch-A-Sketch drawing toy. My guess is that the base layer is the light areas, a mixture of ice and debris impregnated with dust and eroded into the unique Martian geological feature dubbed brain terrain. As for the dark lines and splotches, their explanation might lie in the time of year, the spring.
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The pimpled floor of Isidis Basin on Mars

1:30 pm

The pimpled floor of Isidis Basin on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 21, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely taken not as part of any specific research project but chosen by the camera team to fill a gap in the camera’s schedule in order to maintain its proper temperature.

When they do this they try to pick a target that is somewhat interesting, though it is not always possible. In this case it appears they succeeded in capturing a location filled with lots of puzzling stuff, including low 60-to-80-foot-high mesas with either flat- or hollow-tops, shallow craters that appear almost buried, and other craters that appear so deep and shadowed that it is even possible these are skylights into underground caves.

In between these features the flat landscape has a scattering of ripple dunes, all oriented in the same direction and thus implying that the prevailing winds are or were blowing from the northeast to the southwest.
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Monitoring a changing spot on Mars

1:12 pm

Monitoring a changing landscape on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Based on its label, “Dark Filamentary Streak Year-Round Monitor Site in Promethei Terra,” it was apparently taken as part of a long-term project to monitor the changes that occur at this particular spot on Mars.

This monitoring began in 2008, not long after MRO began science operations. In that first image, taken in the Martian autumn, almost the entire terrain was covered with dust devil tracks, all running more-or-less parallel to each other in a northwest-to-southeast direction.

That unusual tiger-striped landscape prompted later monitoring. However, a follow-up photo in 2010, also in autumn, showed practically no dust tracks here at all. Another image, taken in 2011 during the Martian summer, showed new dust devil tracks, but instead of being aligned as in 2008, the tracks went in all directions, with only a hint of alignment to the southeast.
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Curiosity’s upcoming travel route

12:36 pm

Curiosity's upcoming route
Click for original image.

Overview map
Click for interactive map.

Cool image time! The panorama above, cropped and annotated to post here, was taken on October 6, 2024 by the right navigation camera on the Mars rover Curiosity. It looks south, down the slopes of Mount Sharp and across Gale Crater, the distant crater rim barely visible through the dusty air twenty to thirty miles away.

The overview map to the right provide the context. The blue dot marks Curiosity’s present position. The yellow lines the approximate area covered by the panorama. The red dotted line indicates the rover’s planned route, with the white dotted line the path it has recently traveled.

As you can see, the rover has moved up onto a higher terrace surrounding the Texoli butte, and will now travel downhill a bit to skirt around its northern nose. From there, the science team plans to send the rover westward, traversing along the contour lines on the side of Mount Sharp. Along the way it will lose more elevation, but eventually, after passing several parallel north-south trending canyons, it will finally turn south into one canyon to resume its climb up the mountain.

To review the rover’s journey, Curiosity during its dozen years on Mars has traveled just over 20 miles and climbed about 2,500 feet. The peak of Mount Sharp however is still about 26 miles away and about 16,000 feet higher. Getting there will probably take at least three more decades, which is possible since the rover uses a nuclear power source similar to that used by the two Voyager interplanetary probes, now functioning in space for almost a half century.

In fact, it would not surprise me if the first human Mars colonies are established while Curiosity is still working, and that in its later years it sends its data to that colony directly (via an orbiting relay satellite), rather than beaming it back to Earth.

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Scientists: both liquid water and ice shaped Gale Crater

9:38 am

The uncertainty of science: Using isotope data from instruments on the Mars rover Curiosity, scientists have found evidence that suggests that both liquid water as well as glacial ice helped shape the present geology in Gale Crater.

The paper proposes two formation mechanisms for carbonates found at Gale. In the first scenario, carbonates are formed through a series of wet-dry cycles within Gale crater [involving intermittent liquid water]. In the second, carbonates are formed in very salty water under cold, ice-forming (cryogenic) conditions in Gale crater [involving glacial ice].

“These formation mechanisms represent two different climate regimes that may present different habitability scenarios,” said Jennifer Stern of NASA Goddard, a co-author of the paper. “Wet-dry cycling would indicate alternation between more-habitable and less-habitable environments, while cryogenic temperatures in the mid-latitudes of Mars would indicate a less-habitable environment where most water is locked up in ice and not available for chemistry or biology, and what is there is extremely salty and unpleasant for life.”

…The heavy isotope values in the Martian carbonates are significantly higher than what’s seen on Earth for carbonate minerals and are the heaviest carbon and oxygen isotope values recorded for any Mars materials. In fact, according to the team, both the wet-dry and the cold-salty climates are required to form carbonates that are so enriched in heavy carbon and oxygen.

What I glean from this report is that the evidence that ice played the dominant role continues to build, but since it counters the liquid water theories that scientists have favored for decades they are reluctant to shift entirely to it. It also suggests the geological processes on Mars were far more complex than proposed (no surprise!), and that some mixture of both processes was likely.

This paper is of course merely a newly proposed hypothesis, and therefore its conclusions should be considered only with great skepticism.

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Frozen Martian eddies at the confluence of two glacier rivers

1:46 pm

Frozen eddies at the confluence of two glacial rivers
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 3, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels the photo as capturing a “contact near Reull Vallis,” a 1,000-mile-long Martian canyon that flows down the eastern slopes of Hellas Basin, the death valley of Mars.

What I see isn’t a geological contact but a complex jumble of odd-shaped depressions and mesas, surrounded by an eroded surface that seems squashed and deformed by some process. If this is all we had to go on, I would simply label this as another “What the heck?” image on Mars and move on. However, the larger context of the overview map helps explain it all, at least as best as we can explain using orbital data.
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The strange terrain of the Martian southern ice cap

12:13 pm

The strange terrain of Mars' south pole
Click for original image.

Cool image time! The picture to the right, rotated, cropped, and sharpened to post here, was taken on July 29, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a section at the Martian south pole at the very high latitude of 87 degrees south, only about 100 miles from the pole itself.

The label for this picture is “possible water ice and mesas,” suggesting we are looking at an ice cap of water that is partly sublimated away.

In truth, things are much more complicated. It was summer when this photo was taken. Note the drainage in the lower right and the dark spidery lines there. In the winter on Mars atmospheric carbon dioxide falls as snow and coats the poles to about 60 degrees latitude with a thin mantle of dry ice. In the spring this mantle sublimates away, but does so in an counter-intuitive manner. The sublimation first occurs at the mantle’s base, and the trapped gas flows up until it finds a weak spot in the mantle and cracks through, spewing out and deposting dark splotches of dust.

At the south pole this upward flow always follows the same paths, producing the dark spidery patterns we see here. In the case of the drainage in the lower right, this is a drainage of gas eastward until it pops out at the slope, causing that depression to become darkly stained.

This is only part of the story of this complex geology, however.
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Perseverance looks uphill

9:51 am

Perseverance looks uphill
Click for full resolution. The original images can be found here and here.

Cool image time! The panorama above was created by me from two pictures taken today by the left navigation camera on the Mars rover Perseverance (found here and here). The haziness in the air is the left over from a local dust storm in Jezero Crater during the past month.

On the overview map below, the blue dot marks Perseverance’s present position, with the red dotted line indicating the approximate planned route of the rover uphill. The yellow lines are my guess as to the area covered by the panorama above. That guess could be wrong, as not all the features in the picture match the overview map. The view could be much closer, with the hill and ridgeline nothing more than the small outcrops close to the rover.

Nonetheless, these navigation pictures show us the kind of terrain the rover will be climbing as it works its way up the rim of Jezero Crater. The ground is relative smooth, though steep. My guess is that this is about a 25% grade, which on Earth would be a problem but on Mars it is a grade that NASA’s other rover, Curiosity, has routinely traversed. Perseverance has not yet traveled this kind of steepness, but there is no reason to expect it to have any difficulties doing so.

Overview map
Click for interactive map.

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Curiosity spots a corroded weathered rock

9:15 am

a weathered and corroded rock
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 29, 2024 by the close-up camera mounted at the end of the robot arm of the rover Curiosity on Mars.

This is a small rock, less than three inches across. It is embedded in the sand and soil of Mars, its surface clearly weathered and smoothed by some process. The holes and gaps in the rock could have occurred prior to that smoothing, getting exposed by it. Or possibly the holes developed during the smoothing, with sections breaking off because the material was like sandstone, easily friable.

What caused the smoothing? The data from Curiosity as it climbs Mount Sharp suggests some water process, either flowing water or glacial ice. The scientists at present tend to prefer the liquid explanation, but that requires the Martian atmosphere to have once been much thicker and warmer, conditions that no model has yet demonstrated convincingly was ever possible.

The rock is also likely another example of sulfur, part of the sulfate-bearing unit of geology that Curiosity is presently traversing.

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Crazy swirling Martian landscape

1:48 pm

Crazy swirling Martian landscape
Click for original image.

Cool image time! The picture to the right, cropped, reduced, sharpened, and annotated to post here, was taken on July 1, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “Contacts between Likely Sulfates and Chaos Blocks.” That contact I have indicated with the dotted line. To the west the lighter terrain is likely the sulfate-bearing unit, similar to the sulfate-bearing unit that Curiosity has been traversing on Mount Sharp for the past year or so.

To the east are the chaos blocks, but I think that description is wholly inadequate. In truth, I haven’t the faintest idea how this terrain got to be the way it is. It is evident that a lot of dust and sand has gotten trapped in the hollows, leaving behind ripple dunes in some places, but why the higher ridges swirl and curve about as they do is utterly baffling.
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Monitoring gullies on Mars for changes

12:25 pm

Overview map

Monitoring gullies on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on June 29, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The scientists label the picture simply as “gully monitoring,” with an apparent goal of looking to see if this gully has changed since MRO took the first high resolution image two years previously. In the interim this terrain went from Martian spring, through summer and winter, and has now returned to spring.

As far as I can tell, no changes are visible, but then I am not using the highest resolution data available. Small changes might be detectable in the highest resolution using good detection software. Overall, the gully drops about 3,000 feet.

The white dot in the overview map above marks the location, on the southwest interior rim of an unnamed 30-mile wide crater. This region in the Martian cratered highlands was featured in a four part cool image series I did back 2023 (here, here, here, and here), with this as my conclusion:

Overall, our short survey of the southern cratered highlands suggests that the glacial material and ice found in the southern mid-latitudes affects the Martian surface differently than in the northern lowland plains. In the north the craters and the surrounding terrain often appear blobby, as if the ice is close to the surface and also a dominant component of the ground. Impacts therefore cause significant soft melt features, with craters often heavily distorted. Similarly, there is evidence of the existence of past mud volcanoes that once spewed water and mud from below ground.

In the south however the surface is at a higher elevation, and it appears the ice layer is deeper underground. Thus, it appears the ground is more firm, and the only obvious evidence of an underground layer of ice is revealed when sublimation and the subsequent erosion produce these large pits inside craters.

In the case of this crater, a small impact on its interior southwest slope apparently caused that underground layer of ice to melt temporarily and flow downhill, leaving behind the gully and flow features we see today. Based on the two MRO pictures taken a full Martian year apart, it appears the feature is generally stable and thus likely old, left over from that impact. If things are changing seasonally they are doing so in small amounts and slowly.

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A puzzling striped rock on Mars

9:32 am

A striped rock on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 13, 2024 by one of the high resolution cameras on the Mars rover Perseverance. The rock’s striped nature makes it unique, unlike any feature spotted by any rover previously. From an update today:

The science team thinks that this rock has a texture unlike any seen in Jezero Crater before, and perhaps all of Mars. Our knowledge of its chemical composition is limited, but early interpretations are that igneous and/or metamorphic processes could have created its stripes. Since Freya Castle [the name the science team gave the rock] is a loose stone that is clearly different from the underlying bedrock, it has likely arrived here from someplace else, perhaps having rolled downhill from a source higher up. This possibility has us excited, and we hope that as we continue to drive uphill, Perseverance will encounter an outcrop of this new rock type so that more detailed measurements can be acquired.

Without doubt the rock’s rounded surface suggests it was ground smooth by either water or ice. That surface certainly resembles glacial cobble seen across the northeast of the U.S. where ice glaciers once covered the entire landscape. The rock also resembles river cobble, smoothed by flowing water.

The stripes however suggest that prior to its being smoothed, this rock underwent a much more complex geological process, whereby two different materials were intermixed and squeezed together.

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Layered mesas in Martian chaos

12:27 pm

Layered mesas in Martian chaos
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 19, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a 2,500 to 3,000-foot-high mesa with what the scientists call “bedrock layers”, most obvious as the lower terraces on the mesa’s western slopes.

What makes this mesa especially interesting is its overall shape. It appears as if something has taken a bite out of it, resulting in that bowl-like hollow on the mesa’s southern half.

Was this caused by an impact? Or has some other long term Martian processes caused it?

This mesa is just one of many mesas in a region of chaos terrain dubbed Hydraotes Chaos. Such chaos terrain is thought to form when erosion processes, possibly glacial in nature, that carve out canyons along faultlines, leaving behind mesas with randomly oriented canyons cutting in many directions.
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More deterioration to Curiosity’s worst wheel

12:13 pm

Comparison of changing damage from Feb to Sept 2024
For original images go here, here, and here.

The science team for the Curiosity Mars rover on September 22, 2024 did another survey of its damaged wheels using the close-up camera on the end of the rover’s arm, and though most of the pictures appear to show the situation remains stable, the one wheel that has consistently shown the worst damage now shows some additional deterioration since February 2024.

To the right are comparison pictures, with the February 2024 picture on top and two new September 22, 2024 images showing the same damaged area, though from a different angle, on the bottom. (The technical captions for the bottom images can be found here and here.) I have labeled the treads, dubbed growsers, to make it easier to understand how the pictures all line up.

Previous images have looked down at the large damaged area from growsers 1 to 4, and since it was first spotted in 2022 showed it to be growing, but very slowly. The new pictures show that same damaged area from the side, which reveals that the zig-zag divider between growser #3 and growser #4 has now collapsed, so that this whole damaged area is now a major depression, as indicated by the two arrows.

Overall, the rover’s wheels appear to surviving the rough terrain of the foothills of Mount Sharp, though it is clear that care must continue to be taken to extend their life for as long as possible. That the rover has six wheels gives it a lot of redundancy, so that even if this one wheel eventually fails the rover will likely be able to continue to rove, but with some limitations. This wheel is the left middle wheel, which is helpful, as it is less necessary than the four corner wheels. [Update: According to a rover update today, this wheel is the right middle wheel, which contradicts an earlier report which described this as the left middle wheel. I note this contradiction for accuracy.]

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Land of cracks

1:26 pm

Land of cracks

Cool image time! The picture to the right, cropped to post here, was taken on June 28, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled a “terrain sample,” it was likely taken not as part of any specific research project but to fill a gap in the camera’s schedule in order to maintain its proper temperature. When the camera team needs to do this, they try to pick something interesting, but don’t always have that option.

In this case, the landscape available included the channel shown to the right. About a half mile wide and only about fifty feet deep, the floor of this canyon appears to have a lot of trapped dust, forming ripple dunes, along with a lot of knobby protrusions, likely small mesas. The canyon walls appear layered, with the erosion processes producing different features on opposite sides. On the southeast the layers appear to produce distinct terraces, while on the northwest the cliff is very steep at the top and then forms a long gently descending slope that appears formed of alluvial fill (from that cliff) and formed from erosion and landslides.
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Phobos rising and Earth setting as captured together by Curiosity

10:56 am

Phobos and Earth in the Martian sky
Click for original image.

Cool image time! The picture to the right, enhanced and reduced to post here, was taken by the high resolution camera on the Mars rover Curiosity on September 5, 2024.

What makes this picture unique are the two tiny spots near the upper right. For the first time, Curiosity’s camera was able to capture both the Earth and the Martian moon Phobos in the same picture, when they were also very close to each other in the sky. From the caption:

NASA’s Curiosity Mars rover used its Mast Camera, or Mastcam, to capture this view of Earth setting while Phobos, one of Mars’ two moons, is rising. It’s the first time an image of the two celestial bodies have been captured together from the surface of Mars.

The image is a composite of five short exposures and 12 long exposures all taken on Sept. 5, 2024, the 4,295th Martian day, or sol, of Curiosity’s mission. An inset in the image [found here] shows Phobos on the left and Earth on the right. From the rover’s perspective, the inset area would be about half the width of a thumb held at arm’s length.

The dark shape in the lower left is one of the buttes that surround Curiosity as it has been climbing up Mount Sharp and traversing inside the Gediz Vallis slot canyon.

The inset provides a close-up of the two objects, but the resolution is poor. To me, it is much more interesting to look at the picture to the right, that shows what these two objects actually looked like in the sky of Mars.

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Some new “What the heck?” geology on Mars

1:12 pm

What the heck is going on here?
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on April 21, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

My first reaction on seeing this picture was to scratch my head? What am I looking at? Are those fluted dark features going downhill to the south, or uphill to the north? What are they? Are they slope streaks? Avalanches? How do they relate to the flat-topped ground in the middle of the picture?

I have made it easier for my readers to interpret the picture by adding the “low” and “high” markers. We are looking at two parallel thin mesas about 1,400 feet high, with the saddle between them only dropping about 350 feet.

But what about the dark fluted features? To understand what these are requires more information.
» Read more

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Perservance looks back from on high

10:25 am

Perservance's view looking back down Neretva Vallis
Click for original image.

Cool image time! The picture above, cropped to post here, was taken on September 9, 2024 by the left navigation camera on the Mars rover Perseverance, looking east and back along the route from which the rover had come.

The view is somewhat more spectacular than most Perseverance images because the rover took it during its on-going climb up unto the rim of Jezero Crater, as shown by the overview map below. The blue dot marks Perseverance’s present position, while the yellow lines indicate the area covered by the picture above, taken several days earlier.

The haze in the picture also suggests that the local dust storm first noted in late August might be clearing somewhat. This isn’t certain, however, as the previous picture was using the rover’s high resolution camera to look at distant hills (thus more obscured), while the picture above was taken by the left navigation camera looking more widely and at nearer objects.

Overview map
Click for interactive map.

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New gravity map of Mars released

9:09 am

New global map of Mars gravity field
Click for original image.
Using both seismological data compiled over four years by the InSight Mars lander as well tiny changes in the orbits of Martian satellites, scientists have now created a global gravity map of the red planet, indicating the regions below the surface that are either low or high density.

That map is above, annotated by me to indicate some of Mars’ major surface features.

The density map shows that the northern polar features are approximately 300-400 kg/m3 denser than their surroundings. However, the study also revealed new insights into the structures underlying the huge volcanic region of Tharsis Rise, which includes the colossal volcano, Olympus Mons.

Although volcanoes are very dense, the Tharsis area is much higher than the average surface of Mars, and is ringed by a region of comparatively weak gravity. This gravity anomaly is hard to explain by looking at differences in the martian crust and upper mantle alone. The study by Dr Root and his team suggests that a light mass around 1750 kilometres across and at a depth of 1100 kilometres is giving the entire Tharsis region a boost upwards. This could be explained by huge plume of lava, deep within the martian interior, travelling up towards the surface.

I once again note that the largest impact basin on Mars, Hellas Basin, sits almost exactly on the planet’s far side from Tharsis, and appears to have a light density. This contrast once again makes me wonder if the origin of that impact and the Tharsis Bulge are linked.

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A fluted mesa on Mars

1:27 pm

A fluted mesa on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 9, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “silica-rich mound”, as indicated by the bright streaks on all the high ridge points.

The flat-topped mesa on the right drops about 200 feet to the valley floor. The rims of that depression to the west rise about 50+ feet higher, while mesa nose in the upper left rising another 50+ feet more.

Was the depression caused by an impact? If so, the landscape has changed radically since that impact occurred, with most of the surrounding terrain eroded away. The two flat-topped mesas hint at the ancient surface when that impact occurred.

A wider view however raises questions about this impact theory.
» Read more

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