Tag: geology

New research suggests the two types of streaks on Mars are caused by dry events

9:35 am

A Martian slope streak caused by a dust devil?
A Martian slope streak caused by a dust devil? From
data taken in 2023. Click for original image.

Scientists using a computer machine learning algorithm to assembly and analyze global maps of all known slope streaks and recurring slope lineae (RSL) — the two different types of streaks found on Mars whose cause as yet remain unexplained — have concluded that these streaks are likely caused by dry processes, not wet brine seeping from underground.

Slope streaks can occur randomly throughout the year, can be bright or dark, can occur anywhere, and fade with time. Recurring slope lineae instead appear seasonally in the same locations and are always dark.

You can read the published paper here. It essentially provides further details on research that was first announced at a conference in March. From its conclusion:

[O]ur observations suggest that slope streak and RSL formation may be predominantly controlled by two independent, dry drivers, 1) the seasonal delivery of dust onto topographic inclines, and 2) the spontaneous activation of accumulated dust by energetic triggers – wind and impacts for slope streaks, as well as dust devils and rockfalls for RSL.

…Our results underline the fundamental differences between slope streaks and RSL, despite their visual resemblance. Streak and RSL populations occur on opposite hemispheres (north vs south), at different topographic elevations (mostly lowlands vs mostly highlands), in opposite thermal inertia terrain (low vs high), in different wind speed regimes (above-average vs below-average), in dissimilar diurnal thermal amplitude and heat flux terrain (above-average vs average), in different WEH, H2O, H, and water vapor column terrain (average vs below-average), and in terrain that provides suitable (theoretical) conditions for liquid water at different seasons (Ls ~90° vs Ls ~ 270°).

This data suggests both types of streaks form in connection with very fine Martian dust, but the researchers also admit that the actual method in which these avalanche-type streaks form remains unclear. In both cases the streaks cause no change in the topography (sometimes even traveling uphill for short distances), produce no debris piles at their base, as avalanches typically do, and do not appear to have an obvious cause or source at the top of the streak.

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Curiosity looks uphill at boxwork and future travels

11:06 am

Curiosity's view uphill
Click for original image.

Overview map
Click for interactive map.

Cool image time! The panorama above, taken on May 14, 2025 by the left navigation camera on the Mars rover Curiosity, takes a look uphill at the canyon that the rover is now entering.

The overview map to the right gives the context. The blue dot marks the rover’s location when the picture was taken, and the yellow lines indicate approximately the view of the panorama above. If you look closely at the ground at the base of the cliff on the right, you can see the boxwork ridges indicated on the overview map.

The red dotted line marks the original planned route of the rover. The science team abandoned that plan several months ago in order to get to the boxwork geology as quickly as possible. It expects to reach that boxwork sometime in the next month or so.

Based on the proposed route posted in September 2023, after the scientists have completed their observations of the boxwork the rover will continue uphill within this canyon, bearing east as it parallels that 100-foot-high cliff seen on the horizon. The green dotted line indicates roughly that future route.

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Astronomers observe cloud changes above the northern polar lakes of Titan

10:15 am

Changes seen in Titan's atmosphere
Click for full resolution image.

Using data from both ground- and space-based telescopes, astronomers have now observed clouds rising in the thick atmosphere of the Saturn moon Titan.

The team observed Titan in November 2022 and July 2023 using both Keck Observatory and the James Webb Space Telescope. Those observations not only showed clouds in the mid and high northern latitudes on Titan — the hemisphere where it is currently summer — but also showed those clouds apparently rising to higher altitudes over time. While previous studies have observed cloud convection at southern latitudes, this is the first time evidence for such convection has been seen in the north. This is significant because most of Titan’s lakes and seas are located in its northern hemisphere and evaporation from lakes is a major potential methane source. Their total area is similar to that of the Great Lakes in North America.

The image to the right shows these methane clouds, indicated by the arrows, as seen by Webb on July 11, 2023 and then three days later by Keck. The clouds appear to have shifted downward during these observations.

The data suggests we are seeing one small aspect of Titan’s atmospheric methane cycle, where the liquid methane in the lakes evaporates to form clouds, which later than condense to rain back down. Though superficially similar to the water cycle here on Earth, the details suggest it will be very different on Titan.

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The global distribution of dust devils on Mars

4:13 pm

Global map of dust devils on Mars
Click for original image.

Scientists reviewing the dust devil tracks in orbital images produced by Mars Reconnaissance Orbiter (MRO) have now created a global map that also provides insight into the ground conditions that cause the dust devils to form. From the abstract:

In the first global study of these tracks using high-resolution satellite images from 2014 to 2018, we find tracks in 4% of the images, mostly near 60° north and south latitudes. These tracks are more common during local summers, especially in the southern hemisphere, coinciding with the peak of Mars’ dust storm season, when active dust devils are also more common. Surprisingly, dust devil track (DDT) formation does not depend on elevation, indicating it is not related to the ambient atmospheric pressure. Instead, they occur in darker areas where surface dust covers coarser material, which is revealed as the dust devil moves past.

The white dots on the map above, figure 5 of the paper, shows those MRO images where dust devil tracks were seen. The redish-orange regions are where the data suggests more dust devils should occur, while the blue areas of regions of few dust devils.

The map also notes the locations where Spirit, Opportunity, and InSight landed. Opportunity clearly landed in a region that had more dust devil activity, which explains why its solar panels were cleaned off so regularly by wind. Spirit did not land in such a region, but somehow it was lucky in getting wind events that cleared its panels of dust. InSight had no such luck, and having landed in a region with little dust devil activity, its panels steadily became covered with dust, eventually forcing the end of the mission.

As the paper notes, “To maximize mission lifetimes, future solar powered assets should favor regions where we have identified numerous [dust devil tracks] and where many active [dust devils] are present.” This proposal makes sense, for many reasons. For one, it shifts missions to higher latitudes where many glacial and near-surface ice features are found. Up until now the science community has sent all the landers and rovers to the Martian dry tropics, which has no such near surface ice. For future colonies it is imperative we begin studying Mars’ wetter regions.

This study provides another practical reason for doing so.

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Scientists: Martian gullies formed by CO2 frost, not water flows

3:49 pm

Frost on Martian hillside
Dry ice frost on Martian cliffs. From a 2020 post.
Click for full image.

A new analysis of the gullies found on cliffs on Mars, usually on the interior rims of craters, has concluded that carbon dioxide frost is the cause of the erosion, not ancient flows of water.

This conclusion eliminates the need for liquid flowing water in the Martian past, at least in conjunction with gullies. From the paper’s conclusion:

These results show that CO2 frost is capable of producing Martian gully morphologies. Since flows powered by this process are known to be ongoing and capable of transporting the necessary volume of material, it is the simplest explanation for their formation. Variations in the frequency and fluidity of flows could have occurred over time due to variations in the CO2 cycle. CO2-driven gully formation would indicate that there was not necessarily regular, recurring meltwater during high-obliquity periods. This removes a constraint on recent climate, and also addresses a paradox: if obliquity regularly exceeds the current value as generally thought, and if gullies formed via snow melting at high obliquity, the Late Amazonian Epoch should have included regular snowmelt and widespread aqueous processes. Gully formation by CO2 frost processes is consistent with a cold-desert Late Amazonian with rare or small amounts of liquid water and little aqueous weathering, consistent with the observed mineralogy.

…Gullies, one of the most-discussed lines of evidence for liquid water on Mars, may in fact have no direct connection to H2O. CO2 frost-fluidized gully formation also has broader implications for geomorphology, widening an emerging field of new landform types and processes without Earth analogs. Similar processes could occur on other worlds with erodible substrates on steep slopes and volatile ices at their frost point, although we currently lack the high-resolution images needed to test this hypothesis. Such ices include N2 on Pluto and Triton, and SO2 on Io. [emphasis mine]

In other words, though the gullies appear at first glance to our Earth eyes to have been caused by water flowing downhill, in fact the data now suggests the annual CO2 frost cycle of Mars is the prime cause, even in the distant past. No surface water was required. And since no one has yet come up with a good model for liquid surface water even existing in the Martian past (the atmosphere being too cold and thin), this conclusion helps eliminate this conflict.

The paper also notes the lack of water likely eliminates the need for any planetary protection efforts at these gullies, as the lack of water makes the likelihood of any microbiology nil.

As these conclusions are based on lab work and analysis of images, there remains great uncertainty. Nonetheless, the results help reinforce the arguments that the geological features we see on Mars were formed not by flowing liquid water but by other processes, such as glaciers of ice.

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Bright material on the high points of a Martian mountain

12:29 pm

Bright material on top of a Martian mountain
Click for original image.

Today’s cool image is mostly an example of the present unknowns of Mars. The picture to the right, cropped, reduced, and sharpened to post here, was taken on April 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team quite rightly labels this vaguely as “bright materials,” referring to the bright rim of that crater as well as the scattered bright patches on the surrounding plain. This vagueness tells us that the scientists don’t have enough data yet to definitively identify this stuff, though they know it is distinctly unique because of its inexplicable bright albedo compared to everything around it.

That the crater rim (as well as all the crater rims in the full picture) exhibit this same brightness suggests this material was excavated from below when the impacts hit. The surrounding patches suggest that erosion has exposed this buried material at these points.
» Read more

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Seepage coming from under an ancient Martian flood lava flow?

12:13 pm

Seepage at edge of lava flow?
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on April 3, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

I have enhanced the image to make it easier to see the details. It appears we are looking at three layers. At the base (on the left side of the picture) is a relatively smooth bottom layer with the highest number of scattered craters. On the top (on the right side of the picture) is a somewhat rough layer with fewer craters.

In between is a middle layer that appears to be seeping out from under the top layer.

The science team seems to agree with my last guess, as they label this image “Possible basal seepage at flow boundary.” The flow boundary is the edge of a lava flood that scientists believe covered a distance of about 1,400 miles at speeds ranging from 10 to 45 miles per hour.
» Read more

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A Martian river of ice

11:54 am

A Martian river of ice
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on January 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled it “Looking for Gullies” because the researchers were likely searching for such geological features on the cliff wall that runs down the right side of the picture.

What is more significant however about this picture is the glacier features in the canyon below that cliff. The downhill grade is to the southwest, and it is very evident that the canyon is filled with glacial-type debris, flowing down that grade. Along the base of the cliff the flow seems focused but squeezed, the larger blocks to the west moving slower and thus acting like a wall themselves. In between the flow moves like rapids in a narrow part of a river, albeit in slow motion.
» Read more

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Curiosity’s recent travels as seen from orbit

11:42 am

The view of Curiosity from orbit
Click for original image.

Oveview map
Click for interactive map.

Cool image time! Using Mars Reconnaissance Orbiter (MRO), scientists have captured a very cool image of Curiosity in its recent travels on Mars. That picture is above, reduced and sharpened to post here.

Taken by the HiRISE (High-Resolution Imaging Science Experiment) camera aboard NASA’s Mars Reconnaissance Orbiter, the image shows Curiosity as a dark speck at the front of a long trail of rover tracks. Likely to last for months before being erased by wind, the tracks span about 1,050 feet (320 meters). They represent roughly 11 drives starting on Feb. 2 as Curiosity trucked along at a top speed of 0.1 mph (0.16 kph) from Gediz Vallis channel on the journey to its next science stop: a region with potential boxwork formations, possibly made by groundwater billions of years ago.

The overview map to the right provides some context. Curiosity’s present position is indicated by the blue dot. The yellow lines indicate the approximate section of its past travels photographed by the picture above.

According to the press release at the link, the science team is now estimating the rover will arrive at the boxwork geology in about a month.

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Eroding lava layers in Mars’ volcano country

11:40 am

Eroding lava in Mars' volcano country
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 28, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this picture “enigmatic terrain.” And there are certainly mysteries here. For example, why are there scattered tiny knobs across the surface in the low areas, but not on the higher areas? Also, what caused that top layer to get stripped in places? Was it erosion from wind? Or did some other process cause that layer to vanish in these spots?

Note too that this landscape has few craters. Whatever happened here occurred recently enough that it was able to cover over the impact history from the early solar system that peppered the planets with craters as the planets formed. Though impacts continue even to this day, the impact rate is far less, which allows younger terrain like this to remain largely crater free.

The location provides us some answers, but it still leaves much of this geology a puzzlement.
» Read more

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More wheel damage detected on Curiosity

10:21 am

Increased wheel damage on Curiosity
Click for the Sol 4518 original image.

In a set of new pictures taken of Curiosity’s wheels yesterday it appears that the damage to those wheels has increased significantly in the past year, with the most damaged wheel (which based on contradictory science team reports is either the middle left or middle right wheel), having more had more sections broken to the point where this wheel might even fail in the near future.

The pictures to the right show these changes. The treads, called grousers, have been numbered to make the comparisons easier. The bottom two pictures were taken in September 2024, and look at this wheel with the damage on the side to show how a whole section of the wheel had at that time collapsed to form a depression.

The top two pictures show the increase in the damage in this section between February 2024 and yesterday. Note especially the changes in growlers 4, 5, and 6. Not only have large sections broken off in the wheel’s central section, it appears that the wheel’s outside section is beginning to separate from that central section.

The increased damage in the past year illustrated starkly the roughness of the terrain that the rover is traversing. Moreover, there is no sign that roughness is going to ease anytime in the near future. This increased damage thus explains partly why the science team changed the rover’s route to get to the nearby boxwork geology as fast as possible. That unique geology is likely to provide some important scientific information unobtainable elsewhere, and it seems worthwhile to get to it before this particular wheel fails.

There is one silver lining to this cloud. This particular wheel is a middle wheel, which means it is less critical to maintaining the rover’s stability as it travels as well as sits. The photographs of the other wheels taken today do not show as much change. Even if this wheel fails, the rover will still have five working wheels, including the most essential four corner wheels.

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First images from Lucy’s fly-by of asteroid Donaldjohanson

8:57 am

Asteroid Donaldjohanson
Closest view of asteroid DonaldJohanson.
Click for movie.

The science team for the asteroid probe Lucy today released the pictures taken by the spacecraft as it approached the asteroid Donaldjohanson on April 20, 2025, compiled into a short movie.

The asteroid was previously observed to have large brightness variations over a 10-day period, so some of Lucy team members’ expectations were confirmed when the first images showed what appeared to be an elongated contact binary (an object formed when two smaller bodies collide). However, the team was surprised by the odd shape of the narrow neck connecting the two lobes, which looks like two nested ice cream cones.

…From a preliminary analysis of the first available images collected by the spacecraft’s L’LORRI imager, the asteroid appears to be larger than originally estimated, about 5 miles (8 km) long and 2 miles (3.5 km) wide at the widest point. In this first set of high-resolution images returned from the spacecraft, the full asteroid is not visible as the asteroid is larger than the imager’s field of view. It will take up to a week for the team to downlink the remainder of the encounter data from the spacecraft; this dataset will give a more complete picture of the asteroid’s overall shape.

Lucy is now on its way to the orbit of Jupiter, where it will get close-up views of five different Trojan asteroids in 2027, followed by a later visit to another group of Trojans in 2033.

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Martian ridges that imitate rivers

12:01 pm

Martian ridges that imitate rivers
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists describe these features as “dendritic relief features,” an apt description of the thousands of miles of river-like meandering ridges that orbital images have discovered in the past decade scattered across Mars, as noted in 2016:

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low – in most other environments, the channels are worn away before they can become inverted.

The most dramatic example of these Martian ridge rivers are the fernlike ridges in Antoniadi Crater. The ridges to the right however are almost as striking.
» Read more

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Curiosity drill cores suggest there are more carbon-based minerals on Mars than previously believed

12:19 pm

The uncertainty of science: Scientists studying four different core samples drilled by the Mars rover Curiosity have detected abundant amounts of the iron carbonate mineral siderite, suggesting that there is more carbon within Mars’ crust than previously believed.

If that quantity of carbon is confirmed, there might also have been a carbon cycle between Mars’s atmosphere and the liquid water theorized to have once been on the surface. This cycle could also have made the atmosphere both thicker and warmer, conditions necessary for that liquid water to exist on the surface. From the research paper:

[D]ecomposition of siderite occurred in multiple locations and released CO2 into the atmosphere, recycling CO2 that was originally sequestered during siderite formation. Diagenetic carbonate destruction observed elsewhere on Mars, in martian meteorites, and in sandstones on Earth yields nearly identical reaction products to those we found in Gale crater and are observed globally in orbital data. We therefore conclude that in situ, orbital, and terrestrial analog evidence all indicate that postdepositional alteration of siderite closed the loop in Mars’ carbon cycle, by returning CO2 to the atmosphere.

The uncertainties here are gigantic. For these conclusions to be right, the scientists extrapolate without evidence the same amount of CO2 found in these four cores as existing across the entire surface of Mars. That is a very big extrapolation that no one should take very seriously.

Furthermore, this research assumes the geological features we see on Mars were formed from liquid water. More recent orbital data suggests glacial and ice processes might have played a part instead, with one study concluding that Gale Crater was never warm enough for long-standing liquid water, and that ice and glacial processes must have played the larger part in forming what we find there.

The data from these core samples however is intriguing for sure, though it mostly raises more questions about Mars’ past geological history than it answers.

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Curiosity marches on

12:03 pm

Curiosity looks down hill
Click for original image.

The science team for the Mars rover Curiosity has been moving the rover as fast as it can in order to get to the intriguing boxwork geology about a half mile to the west and slightly higher on Mount Sharp.

The image to the right, cropped, reduced, and sharpened to post here, was taken today by the rover’s left navigation camera, and looks downhill to the north from within the parallel canyon Curiosity entered earlier this week. Because the Martian atmosphere was especially clear at the time, the mountains that form the rim of Gale Crater are quite distinct, 20 to 30 miles away. The view down the canyon also provides a vista of the crater’s floor, more than 3,000 feet below.

In the past two Martian days the science team has had the rover climb uphill a total of 364 feet, a remarkably fast pace considering the rocky nature of the terrain. It appears the engineers have done a spectacular job refining the rover’s software so that it is possible for it to pick its way autonomously through this minefield of rocks, and do so without subjecting its already damaged wheels to more damage.
» Read more

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Myriad flows on mountainous inner crater wall on Mars

1:03 pm

Myriad flows in a crater rim
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 27, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

That the science team labels this “Monitoring Slopes for Changes on Eastern Terraces of Mojave Crater” is quite understandable. The number of apparent dentritic channels suggests strongly the possibility of change over time, which is why MRO has been used repeatedly to monitor this location, beginning in 2006, when the science team noted this in a caption:

Aptly-named Mojave Crater in the Xanthe Terra region has alluvial fans that look remarkably similar to landforms in the Mojave Desert of southeastern California and portions of Nevada and Arizona.

Alluvial fans are fan-shaped deposits of water-transported material (alluvium). They typically form at the base of hills or mountains where there is a marked break, or flattening of slope. They typically deposit big rocks near their mouths (close to the mountains) and smaller rocks at greater distances. Alluvial fans form as a result of heavy desert downpours, typically thundershowers. Because deserts are poorly vegetated, heavy and short-lived downpours create a great deal of erosion and nearby deposition.

There are fans inside and around the outsides of Mojave crater on Mars that perfectly match the morphology of alluvial fans on Earth, with the exception of a few small impact craters dotting this Martian landscape.

» Read more

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Curiosity climbs into a new Martian canyon

1:41 pm

Curiosity looking south
Click image for full resolution panorama. Click here, here, and here for original images.

Overview map
Click for interactive map.

Cool image time! The Curiosity science team has finally completed the rover’s climb up one canyon on the flanks of Mount Sharp and crossed over into a second, switch-backing up through a gap they have dubbed Devil’s Gate.

The panorama above, created from three pictures taken by Curiosity’s left navigation camera on April 9, 2025 (here, here, and here) looks south from that gap. On the horizon about 20-30 miles away can be seen the rim of Gale Crater. From this position the floor of the crater is almost out of side, blocked by the foothills on the lower flanks of Mount Sharp.

Though the ground in this new canyon (on the left of the panorama) continues to be amazingly rocky and boulder strewn, it is actually more benign that the canyon Curiosity has been climbing for the past six weeks.

The blue dot on the overview map to the right marks Curiosity’s present position, with the yellow lines indicating the approximate direction of the panorama. The rover’s next major geological goal is the boxwork to the southwest. In order to get to it quickly the science team decided to abandon its original planned route, indicated by the dotted red line, and climb upward through these canyons.

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Chinese scientists say the lunar far side appears drier than the near side

10:17 am

Map of water measurements of lunar samples
Click for original image.

Based on a comparison of samples brought back by two Chinese unmanned lunar landers, Chinese scientists believe the lunar far side contains far less water in its mantle than the near side.

…the research team focused on analyzing water content and hydrogen isotopes in melt inclusions and apatite within [Chang’e-6] mare basalts—the first samples returned from the farside SPA Basin.

The team’s results indicate that the parent magma of these basalts contain 15–168 μg.g⁻¹ of water. Additionally, the team estimated that the mantle source of the CE6 basalts has a water content of 1–1.5 μg.g⁻¹, significantly lower than that of the nearside mantle. This disparity points to a potential hemispheric dichotomy in the Moon’s internal water distribution, mirroring many of the asymmetrical features observed on the lunar surface.

The map to the right, figure 1 in the scientists’ paper, shows the water content from the samples that have so far been brought back from the Moon. Note how the Chang’e-6 sample shows far less water content than all the near side samples.

Note however also that this is just one data point from the far side. To confirm these conclusions will require many more samples.

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The mighty scale of Mars’ geology

12:16 pm

The mighty scale of Mars
Click for original image.

Today’s cool image is just one more example out of hundreds I have posted in the past decade of the difficult-to-imagine gigantic scale of the Martian landscape.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 1, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image title is simple, “Steep Slopes of Olympus Mons Caldera,” and tells us that this cliff face, about 1,300 feet high, is part of the caldera that resides on top of Mars’ largest volcano, Olympus Mons.

The parallel cracks on the plateau above the cliff tell us that the cliff face is slowly separating outward from that plateau, and that at some point in the future the entire wall will collapse downward.

Sounds impressive and big, eh? What the picture doesn’t make clear however is how truly tiny this cliff is in the context of the entire mountain.
» Read more

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Another “What the heck?!” image on Mars

1:48 pm

Another
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this “Monitoring Irregular Terrains in Western Arabia Terra.” I label it more bluntly as another one of MRO’s “What the heck?!” images. For all I know, this is nothing more than a discarded Vincent Van Gogh painting, thrown out because even he couldn’t figure out what he was painting.

The best guess I can make, just from the picture alone, is that some of the dark spots are vents from which the white stuff vented at some point, either as small lava or mud volcanoes. As the location is close to the equator, near surface ice is almost certainly not a factor in what we see.

In any case there is no way to reasonably decipher this picture, just by looking at the picture. It is necessary to take a wider view.
» Read more

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