Tag: geology

Wind-blown dark material on Mars

11:59 am

Dark wind-blown material on Mars
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on May 13, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a cluster of small depressions from which has blown dark material across the ground to the south. The full image also shows two craters north and south of this cluster that have similar dark material blown from their interiors.

When I first looked at this image, I wondered if the dark material and these depressions signaled a recently active volcanic vent where magma had spewed upward to stain the nearby ground. See for example this recent post about what some scientists believe might the most recent volcanic event so far found on Mars. I emailed several scientists for their thoughts, all of whom said this appears to not be active volcanism but merely windblown dark material.

Kim Seelos, science operations lead for MRO’s visible-near infrared spectrometer, put it simply. “My own reading of this image is that the dark areas here are likely akin to wind streaks.” Instead of the dark material being thrown from the depressions by a volcanic event, it was swept to the south by the prevailing winds.

How that dark material got into the depressions, and why it was so comparably darker than the surrounding terrain, remains unclear. David Horvath of the Planetary Science Institute in Arizona speculated that the low hills just north of the dark patch might be a factor.
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First hi-res radio wavelength images of metal asteroid Psyche

9:46 am

Psyche in thermal

Using the ALMA telescope in Chile astronomers have obtained the highest resolution radio images of the surface of the metal-rich asteroid Psyche yet obtained. The image to the right is from their just published paper. From the article:

These new images reveal that some regions of the asteroid have surface temperatures different from the average, indicating that Psyche’s composition is not uniform. The researchers also found that Psyche has a relatively high thermal inertia compared to other asteroids, yet it radiates approximately 60% less heat than would be expected for an object with such a high inertia. The researchers hypothesize that this is because the asteroid’s surface is at least 30% metal. However, the light reflecting off Psyche’s surface is unpolarized, which would not be the case for an object with a smooth or solid metallic surface. They therefore hypothesize that metallic grains are spread throughout its surface material, causing the light to scatter.

Though Psyche is large, 178 by 144 by 101 miles, it is not spherical like Ceres, the largest asteroid in the asteroid belt at 580 miles diameter. Thus, somewhere from the size of Psyche to the size of Ceres we move from an irregular asteroid body to a spherical planetary body, as it appears most planetary scientists define planets.

The probe Psyche is scheduled to launch in August ’22 to arrive at Psyche in ’26.

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Curiosity’s coming mountainous target

10:38 am

Curiosity's upcoming mountainous target
Click for full image.

Overview map


Click for interactive map.

Cool image time! The photo above, taken on August 22, 2021 by Curiosity’s left navigation camera and reduced to post here, looks ahead at the rover’s upcoming mountainous goals. The overview map to the right shows the area covered by this image by the yellow lines. The dotted red line indicates the rover’s original planned route, with the white dotted line its actual path of travel.

The cliff ahead is about 400-500 feet away. The top of this cliff is the Greenheugh Pediment, its blocky top geological layer visible as the dark cap at the top of the cliff face. Back in March 2020 Curiosity had climbed up to view across this pediment, from a point to the northwest and off the overview map to the left. (Go to this link to see what the view was like from there.) Since then the science team has had the rover travel quite a distance, to circle around to now approach the pediment from the east.

The white box marks the area covered by a close-up high resolution mast camera image, shown below.
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New cracks across old Martian lava flows

1:03 pm

New cracks across an old lava flow
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It captures one of the many deep straight fissure canyons that make up the feature dubbed Cerberus Fossae in the center of Mars’ volcano country.

The crack is called a graben, and happens when the ground is either stretched from pressure from below, or when two adjacent large blocks of material move sideways relative to each other.

What makes this particular graben interesting are two features. First, the overlapping break suggests something complex took place at this spot when the crack separated. Second, the crack cut across the foot of an older frozen lava flow, meaning it has to be younger than that flow.

The overview map below provides a clue when that lava flow might have occurred, while also suggesting this crack in Cerberus Fossae might be much younger than expected.
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Perseverance’s next drill attempt

9:40 am

Perseverance short term planned route
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The Perseverance science team today announced its near-future plans for where it will send the rover, but also when and how it will attempt its next core sample drilling.

The map to the right, cropped and reduced to post here, shows the rover’s future route. The red dot indicates its present location. The blue dot indicates where next they will attempt to drill. The route shows that they have decided to also make a short side trip south, an target that until now was considered optional.

As for what they plan to do in that next drill attempt:

We will first abrade the selected rock and use the science instruments to confirm (to the best of our ability) that the new target is likely to result in a core after the sampling process.

If we choose to sample the rock, Perseverance will perform a set of activities very close to what was done on the prior coring target. The main difference will be, after coring, we’ve added a “ground in the loop” session to review the images of the tube in the bit and confirm a sample was collected. Then, the tube will be transferred into the rover for processing.

If post-coring imagery shows no sample in the tube, we may elect to try again, using an alternate geometry (e.g. more horizontal) for the coring activity. Another option, if the targeted rock doesn’t allow for a change in geometry, is to look for a different rock in this region that is more easily cored horizontally.

They really want to get a sample of this particular bedrock on the floor of Jezero Crater. Their problem is that the first core sample failed because the bedrock was too structurally weak, crumbled into powder during drilling, and thus poured out of the drillbit once retracted from the ground. It could be that this will be a consistent issue with any sample attempts in this bedrock. This is why they are also considering drilling sideways, in order to hold any material they grab.

I suspect that the short side trip south might be to an outcrop that the rover could drill sideways into. Thus, if they are successful in getting a sample at the blue dot they might still cancel that side trip.

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A weak avalanche season on Mars?

1:39 pm

The north pole scarp
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Today’s cool image from Mars is cool both for what is visible in the photo and for what is not, the latter of which might turn out to be a discovery of importance.

The photo to the right, cropped and reduced to post here, was taken on June 24, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a section of the edge of Mars’ north polar ice cap, with north at the top.

This scarp is probably more than 2,000 feet high, though that height drops to the south as the upper layers disappear one by one from either long term erosion or sublimation. Those layers represent the visible information in the photo that is cool. They give us tantalizing clues about the geological and climatic history of Mars. Each layer probably represents a climate period when the north icecap was growing because the tilt of the planet’s rotation was even less than the 25 degrees it is now. When that tilt is small, as small as 11 degrees, the poles of Mars are very cold, and water ice migrates from the mid-latitudes to the poles, adding thickness to the icecaps. When the tilt grows, to as much as 55 degrees, the mid-latitudes are colder than the poles, and the water ice migrates back to the mid-latitudes.

What is not visible in this picture, however, might be far more significant.
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A dry bedrock Martian crater floor?

1:01 pm

A dry bedrock crater floor?
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is a very eroded crater at about 26 degrees north latitude. The image shows the crater’s crater floor, with a variety of bedrock-type features, sharp ridges, abrupt scarps, and flat smooth plateaus, with a hint of lobate glacial flows in the image’s southeast quadrant.

At 26 north latitude, it is unlikely that anything here is icy, unless it is very well protected by debris. Most of these features are almost certainly bedrock, though their formation could very well have been shaped by ice in past eons when this location was more amenable to water ice.

The wider MRO context camera image of the entire crater, plus the overview map, give a larger picture, and raise some interesting questions.
» Read more

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Curiosity produces new 360 degree hi-res panorama

9:50 am

360 degree hi-res panorama from Curiosity
Click for full resolution image.

The Curiosity science team has used the rover’s high resolution camera to produce a new 360 degree panorama, with the center of the image looking directly up at Navarro Mountain.

To get a really good idea of what this panorama shows, I have embedded below a video the scientists have produced giving a tour of the image, which reveals two especially interesting details. First, their future route will go between Navarro Mountain (the highest visible peak) and the 80-foot-high dark butte to its right. This is as planned, as indicated by the red dotted line on the overview map show in this July 8, 2021 post.

Second, the air was very clear when this panorama was taken, and so the rim of Gale Crater can be distinctly seen, 20 miles away.

» Read more

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Zhurong completes its planned 90-day mission on Mars

8:54 am

China’s state-run press announced today that its Mars rover Zhurong has successfully completed its planned 90-day mission, is operating without issues, and will continue its exploration of the Red Planet.

The rover has traveled 889 meters as of Aug. 15, and its scientific payloads have collected about 10 Gb of raw data. Now the rover runs stably and operates in good condition with sufficient energy. The CNSA added that the rover will continue to move to the boundary zone between the ancient sea and the ancient land in the southern part of Utopia Planitia and will carry out additional tasks.

According to the administration, Zhurong operated with a cycle of seven days during its exploration and detection. Its navigation terrain camera obtained topographic data along the way to support the rover’s path planning and detection target selection.

Zhurong’s subsurface detection radar acquired the data of the layered structure below the Martian surface, which analyzes the shallow surface structure and explores the possible underground water and ice. [emphasis mine]

This announcement reveals two tantalizing details. First, they are extending the mission, and plan to continue traveling to the south, with a very long term fantasy goal of reaching the transition zone between the northern lowland plains that Zhurong landed in and the southern cratered highlands. That fantasy goal is about 250 miles away. At the pace Zhurong is traveling, about 1,000 feet per month, it will take about a 100 years to cover that ground. Even so, as they move south they are slowly going up hill, and have the chance of seeing some change in the geology along the way.

The second tantalizing detail is indicated by the highlighted last sentence, and is probably the most important data obtained by Zhurong. It suggests they obtained good data from the rover’s ground penetrating radar, and it indicated the existence of underground layers. Whether those layers contain ice however is not clear. From the story it appears the data has not yet been analyzed enough to say.

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Lacy patterns in the high north of Mars

12:27 pm

lacy patterns in the high north of Mars

Cool image time! The photo to the right, cropped, reduced, and rotated so that north is up, was taken on May 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the strange lacy patterns seen routinely in the very high northern latitudes surrounding the Martian north pole.

Located in a region of the vast northern lowland plains dubbed Scandia Tholi, such features are apparently common here. From a 2011 geology paper of the region’s geological history:

We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters.

The small circular feature near the bottom of the picture appears to be a mesa, and might be a pedestal crater, so old that the surrounding terrain has worn away and left the hardened-by-impact crater as a butte. To its right is a larger circular mesa with its scarp well eroded into hollows. This might also be a pedestal crater, or not.

The white lacy patterns could be frost, either water ice or dry ice. That the white lace tends to favor the north-facing slopes lends support to this guess. The photo was taken in the early spring, so the thin mantle of carbon dioxide that falls to cover the polar region south to sixty degrees latitude is only beginning to sublimate away.

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Ingenuity’s 12th flight successful

9:15 am

Ingenuity's shadow just before landing.

According to the Perseverance science team, the Mars helicopter Ingenuity successfully completed its twelfth flight on Mars early yesterday, making a short scouting round trip over an area called South Seitah to provide images that the team can use to plan the rover’s future route.

All told, Ingenuity flew just under 1,500 feet flying about 30 feet above the ground for just under three minutes. The picture to the right was taken just before landing, and shows the helicopter’s shadow on the ground. It is one of six so far downloaded. The remaining images will follow later.

The announcement was made on Twitter, and included some embarrassingly over-the-top prose:

The #MarsHelicopter’s latest flight took us to the geological wonder that is the “South Séítah” region.

South Seitah is hardly a “geological wonder”. It is a sandy area with some rocks and interesting geology.

I’m not sure why, but the Perseverance rover team seems prone to do this with their press releases and announcements. The claim they make over and over that Perseverance’s prime mission is to look for ancient life is junk Now they call a relatively undistinguished and small area on a crater floor a “wonder.”

Makes one think they somehow feel a need to justify what they are doing, something that is patently absurd. They are controlling a robotic rover and helicopter tens of millions of miles away as both explore a place on another planet no one had ever visited before. That certainly is spectacular enough, and does not need purple prose to justify.

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Regional Martian dust storms help suck water from Mars

2:55 pm

Orbital data now shows that both global and regional dust storms on Mars help remove the planet’s water, allowing it to reach higher atmospheric elevations where solar radiation breaks it up and it escapes into space.

Scientists have long suspected that Mars, once warm and wet like Earth, has lost most of its water largely through this process, but they didn’t realize the significant impact of regional dust storms, which happen nearly every summer in the planet’s southern hemisphere. Globe-enveloping dust storms that strike typically every three to four Martian years were thought to be the main culprits, along with the hot summer months in the southern hemisphere when Mars is closer to the Sun.

But the Martian atmosphere also gets heated during smaller, regional dust storms, according to a new paper published August 16 in the journal Nature Astronomy. The researchers, an international team led by Chaffin, found that Mars loses double the amount of water during a regional storm as it does during a southern summer season without regional storms.

This conclusion is based on data gathers from three different orbiters during a regional dust storm in early 2019.

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