Tag: geology

Sightseeing near Starship’s candidate Martian landing sites

2:21 pm

An interesting mesa near Starship's Martian landing zone
Click for original image.

Today’s cool image takes us sightseeing in the region on Mars that SpaceX has chosen for its prime landing zone for its Starship spaceship. The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a 465-foot-high unusually shaped mesa in this region.

The full resolution inset at the bottom of the picture focuses at the strange tilted layers on the southern slope of this mesa. Apparently the layers at this spot were pushed sideways so they lie significantly angled to the horizontal. Though it isn’t clear from this picture, it is possible that the mesa itself is made up of similar tilted layers, hidden below the surface. We can see the tilt only on the mesa’s southern flank because erosion has apparently exposed it.

Note also the black stain that surrounds the mesa. Though this might be caused by wind distributing dust, such stains have also been seen at a location where scientists suspect an inactive hot spring might exist, as well as another location where there may have been relatively recent volcanic activity.

Is this stain caused by any of these processes? In situ exploration would probably be necessary to find out. And we may soon actually have spaceships landing here in the relatively near future with the capability to do this.
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Returning to Mars’ glacier country

3:21 pm

Overview map

Returning to Mars' glacier country
Click for original image.

Today’s cool image illustrates again why I rail against those who still claim Mars is dry. The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture was labeled simply as a “terrain sample” by the MRO camera team, which almost always signifies that it was taken not as part of any specific science research project or by request by a scientist, but to fill a gap in the camera’s schedule in order to maintain its proper temperature. When such a gap-filler picture is required, the team tries to pick interesting features in that time frame, but don’t always succeed.

In this case, that time frame placed MRO over the northern mid-latitudes and a region I label “glacier country” because practically every picture taken in this region shows glacial features. This picture is no exception. The white dot in the overview map above marks the location, in the Protonilus Mensae area of the 2,000-mile-long strip of glaciers. The arrow in the picture itself shows the downward grade of the glacial flow. The small 2,000-foot-wide crater appears as if the impact occurred on soft ice, and the stippled terrain surrounding it appears to resemble the feature geologists have labeled “brain terrain”, a surface feature unique to Mars and associated with near surface ice, though its exact formation process is not yet understood.

Nor have I cherry-picked this image to prove my point. Its glacial-like features are very typical for this region of Mars. Note for example the inset with the larger crater to the northeast. It appears almost buried by this glacial material, which has poured through the gap in its southwest quadrant to fill it. A close look at all the low lying terrain shows similar glacial-like flows.

Mars is surely not a paradise. It is bone-chillingly cold almost all the time. Its atmosphere is so thin and lacking in oxygen you would quickly suffocate if you tried to breath it. But the data continues to suggest that the red planet has ample supplies of near-surface ice outside of its dry tropics. All future colonists will need to do is dig a bit and process the water out.

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Mars is not dry!

11:11 am

Global map of glaciers found on Mars

I once again feel compelled to rant against the shallow ignorance of too many people in both the journalism field as well as academia about the most recent data we now have of Mars. Two articles today once again show this ignorance, assuming blandly that Mars is a dry planet with little water on it anywhere, when orbital data over the past decade has unequivocally shown that — except for its equatorial regions — the planet is covered with a LOT of near-surface ice.

The headlines make this ignorance quite clear:

In both cases, the articles assume that the data obtained from rovers and landers in the dry Martian tropics applies to the entire planet. It does not. This evidence of a dry planet carries a bias that comes from the decision by the planetary community as well as NASA to send every rover to that dry equatorial region. Only one lander, Phoenix, has ever been successfully dropped far from the Martian equator, and it was purposely sent to a very high latitude, where it proved there was ice present just below the surface.

Orbital data in the past decade from both Mars Reconnaissance Orbiter and Mars Express has clearly shown that there is a lot of near surface ice on Mars, as shown by the map above. In the mid-latitudes the terrain is dominated by glaciers, as this is the region where the vast ice sheets in the high latitudes begin to fade away.

Only the equatorial region, indicated by the white lines on the map, is dry and barren. And yet, even here, orbital data has detected evidence that suggests underground ice still exists.

It seems to me that journalists and academic PR departments should know these facts, and include them in any reports about the dry nature of Mars’ equatorial regions.

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The sagging flank of one of Mars’ giant volcanoes

1:51 pm

The sagging flank of Elysium Mons
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 1, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “chain of pit craters in [a] graben”.

A graben is a surface fissure created when the surface either spreads or two sections shift sideways in opposite directions. The chain of pits suggest that there is a larger void below into which the surface is sinking. It is also likely that a lot of the sinking material is volcanic ash, thrown free in an eruption hundreds of millions of years ago, which over the eons has been blown up to this location to settle in the crack to fill it. It is now trapped there, and sinking.

What caused the ground here to shift and create the fissure? In this case, the cause is quite large and massive, in a way that boggles the mind.
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The source of a Martian glacial canyon 750 miles long

2:21 pm

The source of a Martian glacial canyon 750-miles-long
Click for original image.

Cool image time! The picture to the right, cropped, reduced, sharpened, and brightened to post here, was taken on May 1, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this very simply as a “wall on Ausonia Cavis”. Ausonia Cavis — 31 miles long and 20 miles wide at its widest — is one of the many gigantic sinks found in many places on Mars. This particular cliff wall is about 2,000 feet high, though from rim to floor of the sink is closer to 3,000 feet.

The image was likely taken to get a closer look at those gullies flowing down the cliff wall. Previous research of similar cliff walls in this region has found what appears to be seasonal water frost in such gullies, and this image was likely taken to see if more such frost could be spotted here as well.
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Sublimating ice in the Martian dry tropics?

2:31 pm

Sublimated ice in the Martian dry tropics?
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 3, 2025 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 the camera’s proper temperature.

When the MRO camera team does this, they try to pick features of interest at the time required, and I think succeed more often than not. In this case, they captured this one-mile-wide unnamed crater that appears to be filled with sublimating glacial debris. Similarly, the plateau surrounding the crater seems to also show signs that some sublimation is occurring of ice just below the surface, producing the areas that appear filled with pockmarks.

The location however suggests that if near surface ice here is sublimating away, it hints at a find of some significance.
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Mars will be mystery until we can walk its surface

1:43 pm

A Martian mystery
Click for original image.

Today’s cool image illustrates starkly the limitations of orbital imagery. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 30, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows flow features inside a depression that strongly resemble glacial features, with the downhill grade roughly heading south.

Such features are seen in many places on Mars, almost always in the 30 to 60 degree mid-latitude bands in both the northern and southern hemispheres (see here, here, and here for just three examples. For many more simply search this website using “glacier” or “glacial feature” as search terms).

The problem is that this location is not within that 30 to 60 degree latitude band. In fact, at this location no near surface ice should exist at all.
» Read more

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The mad mountains of Mars

10:34 am

The mad mountains of Mars
Click for original image.

Overview map
Click for interactive map

Cool image time! The picture above, cropped to post here, was taken on June 10, 2025 by the high resolution camera on the Mars rover Curiosity, and shows some of the stranger terrain found higher up the flanks of Mount Sharp in Gale Crater.

The blue dot on the overview map to the right marks Curiosity’s present position, where it is doing another drilling campaign into the first boxwork geology it has encountered. The white line marks its past travels, while the green dotted line its planned route.

The yellow lines indicate the area seen in the picture above. The wild mountain peaks on the horizon are part of the sulfate-bearing unit that appears very bright in the overview map. The material that makes up this terrain appears to be very easily eroded, based on its features as seen from orbit, as well as Curiosity’s distant view. Whether that erosion was wind, water, or ice, remains undetermined, and is the main question Curiosity will attempt to answer once it gets there, likely in a year or so.

Regardless, the landscape appears almost like it soft sand being washed away.

Where the rover will go next the science team has not yet decided. It will definitely continue uphill, but they do not yet know the route they will take through that sulfate-bearing unit.

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The dusky mountains of Mars

10:10 am

The dusky mountains of Mars
Click for high resolution. For the original images, go here, here, and here.

Overview map
Click for interactive map.

Cool image time! The panorama above, created from three images taken on June 7, 2025 (here, here, and here) by the high resolution camera on top of the Mars rover Curiosity, looks south and uphill into the Gediz Vallis canyon that the rover had been traveling previously.

The overview map to the right provides context. The blue dot Curiosity’s present position, where it is about to begin a drilling campaign into the first boxwork structures the rover has reached. The white dotted line marks its past travels, while the green dotted line its planned future route. The red dotted line marks a planned route that has been abandoned.

The yellow lines indicate approximately the area covered by the panorama. Because this used the rover’s high resolution camera, the view gives us a detailed look at the mountains on the distant horizon. Though we are looking uphill, the peaks in the distance are merely higher ridges and hills on the flanks of Mount Sharp. The mountain’s peak is out of view, about 25 miles away and about 15,000 feet higher up.

Note the dusty and what appears to be a softened nature of the terrain on these higher peaks. Since entering the foothills of Mount Sharp several years ago, the surface has been extremely rocky and rough, every inch covered in boulders of all sizes. This distant view suggests the ground might become easier to traverse at those higher altitudes. It also appears there will be a lot more dust, coating everything.

The lighting I think is close to natural. Because Mars is farther from the Sun, it doesn’t get as much light. Even during mid-day the light to our Earth-borne eyes would more resemble dusk on Earth.

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Scientists believe they have detected the actual process in which Mars loses its atmosphere

10:13 am

The uncertainty of science: Scientists using three different instruments on the Mars orbiter MAVEN now believe they have detected evidence of the actual process in which Mars loses its atmosphere, dubbed “sputtering”.

To observe sputtering, the team needed simultaneous measurements in the right place at the right time from three instruments aboard the MAVEN spacecraft: the Solar Wind Ion Analyzer, the Magnetometer, and the Neutral Gas and Ion Mass Spectrometer. Additionally, the team needed measurements across the dayside and the nightside of the planet at low altitudes, which takes years to observe.

The combination of data from these instruments allowed scientists to make a new kind of map of sputtered argon in relation to the solar wind. This map revealed the presence of argon at high altitudes in the exact locations that the energetic particles crashed into the atmosphere and splashed out argon, showing sputtering in real time. The researchers also found that this process is happening at a rate four times higher than previously predicted and that this rate increases during solar storms.

This sputtering is believed to be the process in which Mars lost the thick atmosphere that scientists believe must have existed in the past so that liquid water could exist on the planet’s surface. When MAVEN arrived in Mars orbit ten years ago the scientists actually thought the spacecraft would detect it relatively quickly. That it took ten years to finally find some evidence it is occurring suggests something is not quite right with their theories.

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New data suggests Europa’s surface is constantly changing

9:26 am

Webb data showing variations on Europa's surface
Click for original graphic.

The uncertainty of science: Using data collected by the Webb Space Telescope combined with modeling and lab experiments, scientists now think they have found evidence that Europa’s surface is constantly changing, with materials from its interior being brought to the surface.

This new study found crystalline ice on the surface as well as at depth in some areas on Europa, especially an area known as Tara Regio. “We think that the surface is fairly porous and warm enough in some areas to allow the ice to recrystallize rapidly,” said Dr. Richard Cartwright, lead author of the paper and a spectroscopist at Johns Hopkins University’s Applied Physics Laboratory. “Also, in this same region, generally referred to as a chaos region, we see a lot of other unusual things, including the best evidence for sodium chloride, like table salt, probably originating from its interior ocean. We also see some of the strongest evidence for CO2 and hydrogen peroxide on Europa.”

…“Our data showed strong indications that what we are seeing must be sourced from the interior, perhaps from a subsurface ocean nearly 20 miles (30 kilometers) beneath Europa’s thick icy shell,” said [Dr. Ujjwal Raut of the Southwest Research Institute and co-author of the paper]. “This region of fractured surface materials could point to geologic processes pushing subsurface materials up from below. When we see evidence of CO2 at the surface, we think it must have come from an ocean below the surface.”

The graphic to the right shows the detected variations across the surface of Europa, based on the Webb spectroscopic data. It also illustrates nicely the coarseness of this data, its lack of resolution, and the uncertainties involved. The scientists have found evidence that suggests the surface is changing, but the key word here is “suggests”. They have not yet directly seen any actual changes, such as changes between two images taken at different times.

Nonetheless, the data does point in the right direction. Moreover, it would be far more unlikely if nothing on Europa changed. The fundamental question that remains unanswered is how fast things change there. And we won’t have any chance to answer this question until Europa Clipper enters Jupiter orbit in 2030 and begins multiply fly-bys of Europa.

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The canyon that Curiosity will eventually climb

11:36 am

The canyon that Curiosity will eventually climb
Click for full resolution. For original images go here and here.

Overview map
Click for interactive map.

Cool image time! The panorama above, created from two photographs taken on May 23, 2025 by the left navigation camera (here and here) on the Mars rover Curiosity, looks south uphill into the canyon that Curiosity is eventually going to climb.

The overview map to the right provides the context. The blue dot marks Curiosity’s present position, the white dotted line its past travels, the red dotted line its initial planned route, and the green dotted line its future route. The yellow lines indicate the approximate area seen in the panorama above.

If you look on the horizon to the left, you can see very bright terrain higher up the mountain. This is the pure sulfate-bearing unit that is Curiosity’s next major geological goal. It won’t reach that terrain for quite some time however because first the scientists want to spend some time studying the boxwork geology that Curiosity is now approaching. That boxwork suggests two past geological processes, as yet unconfirmed. First it suggests the ground dried like mud, forming a polygon pattern of cracks that then hardened into rock. Second, lava seeped up from below and filled those cracks. The lava, being more resistant to erosion, ended up becoming the boxwork of ridges as the material around eroded away.

This proposed history however is not proven. They hope to find out when Curiosity gets there.

Meanwhile, despite having traveled almost 22 miles, the rover is more than 25 miles from the peak of Mount Sharp, which remains out of sight. That peak is also about 15,000 feet higher.

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Scientists: Jezero Crater’s theorized lake overflowed intermittently four times in the past

10:42 am

The inlet and outlet valleys of Jezero Crater
Click for original image.

Scientists analyzing the Martian geology of the meandering outflow canyon from Jezero Crater, now think it was formed by four different very short-lived events when the theorized lake inside the crater overflowed the crater rim.

The map to the right, figure 1 of the paper (cropped and annotated to post here), provides the context. Two canyons, Sava Vallis and Neretva Vallis feed into Jezero Crater, and one canyon, Pliva Vallis, flows out. From the abstract:

By examining the shape of the valley, we noticed that Pliva Vallis was not like valleys carved by continuous rivers on Earth and propose instead that the valley was carved by at least four episodes of lake overflow. To give a minimum estimate of the duration of these events, we use a numerical model to simulate the overflow of a lake and the incision of a valley. Modeling suggests that the four (or more) episodes identified each incised part of the valley and that each episode lasted a few weeks at maximum.

The researchers also considered whether Pliva Vallis could have been carved by glacial flows, but rejected that possibility partly because “the general morphology of the valley shows a decrease in depth and width downstream, while subglacial channels [on Earth] tend to remain of similar width or become larger, as the flow regime does not decrease downstream.”

These conclusions of course carry a great deal of uncertainty. For one, they are based solely on orbital data. No ground truth exists as yet. Secondly, they assume the geology on Mars behaves in the same manner as on Earth. It could very well be for example that the reason the valley shrinks in size is because its Martian glacier sublimated away as flowed downhill, something that doesn’t happen on Earth.

Regardless, the data strongly suggests that water shaped Jezero in some manner.

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Perseverance moves across the barren outer rim of Jezero Crater

10:46 am

Looking back at the rim of Jezero Crater
Click for full resolution. For original images go here and here.

Overview map
Click for interactive map.

Cool image time! While most of the mainstream press will be focusing today on the 360 degree selfie that the Perseverance science team released yesterday, I found the more natural view created above by two pictures taken by the rover’s right navigation camera today (here and here) to be more immediately informative, as well as more evocative.

After spending several months collecting data at a location dubbed Witch Hazel Hill on the outer slopes of the rim of Jezero Crater, the science team has finally had the rover move south along its planned route. The overview map to the right provides the contest. The blue dot marks Perseverance’s present location, the red dotted line its planned route, and the white dotted line its actual travels. The yellow lines mark what I think is the approximate area viewed in the panorama above.

That panorama once again illustrates the stark alienness of Mars. It also shows the startling contrast between the rocky terrain that the rover Curiosity is seeing as it climbs Mount Sharp versus this somewhat featureless terrain traveled so far by Perseverance. Though Perseverance is exploring the ejecta blanket thrown out when the impact occurred that formed Jezero Crater, that event occurred so long ago that subsequent geological processes along with the red planet’s thin atmosphere have been able to smooth this terrain into the barren landscape we now see.

And barren it truly is. There is practically no place on Earth where you could find the surface so completely devoid of life.

Some would view this as a reason not to go to Mars. I see it as the very reason to go, to make this terrain bloom with life, using our fundamental human ability to manufacture tools to adapt the environment to our needs.

Meanwhile, the science team operating Perseverance plans to do more drilling, as this ejecta blanket probably contains material thrown out from the impact that is likely quite old and thus capable of telling us a great deal about far past of Mars’ geological history.

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Terraced Martian butte

12:44 pm

Terraced Martian butte
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on April 1, 2025, by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this as a “Layered Butte.” Seems like a good description. From top to bottom there appear to at a minimum about a dozen terraces, each of which represents a specific geological era on Mars.

I post this mostly because I think it shows us another example of the alien beauty of the Martian landscape. The scientific question of course is what do these layers represent. In a general sense, they indicate that over a long time period one by one these layers were laid down, and then over a likely equally long time period the top layers were worn away, one by one. The mesa is just a random spot where that erosion process was not complete, leaving behind this terraced 400-foot-high tower.
» Read more

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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.
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A Martian river of ice

11:54 am

A Martian river of ice
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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.
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Curiosity’s recent travels as seen from orbit

11:42 am

The view of Curiosity from orbit
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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
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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.
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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
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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.
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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
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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.
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