The ancientness of rocks on Mars

Ancient rocks on Mars
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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on December 27, 2023 by the high resolution camera on the Mars rover Curiosity. It shows what is a somewhat typical rock found on the ground as Curiosity climbs Mount Sharp in Gale Crater.

Two features stand out. First, the many layers illustrate again the cyclical nature of Martian geology. Many sedimentary events occurred over a long time to create this rock, each cycle putting down a new layer, with some intervening time periods possibly removing layers as well. Such layering has now become evident in both ground photos taken by rovers as well as orbital images.

Second, the delicate nature of some layers indicates the incredibly slow erosion process on Mars, enhanced by the red planet’s one-third gravity. The atmosphere is incredibly thin, less than 0.1% of Earth’s. Yet given time the wind had been able to wear away the edges of this rock. The thin atmosphere and light gravity has also allowed some material to remain in a delicate manner that would be impossible on Earth.

Thus, for these thin flakes to have formed has required a great deal of time. The very nature of this rock speaks of an ancient terrain, shaped slowly by inanimate processes with no active life around to disturb things.

Curiosity science team releases movies of Mars from dawn to dusk

Using its front and rear hazard avoidence cameras, the Curiosity science team had the rover take two full sets of images looking in one direction for twelve hours straight in order to create two movies of Mars that show an entire day, from dawn to dusk.

I have embedded both movies below. From the press release:

When NASA’s Curiosity Mars rover isn’t on the move, it works pretty well as a sundial, as seen in two black-and-white videos recorded on Nov. 8, the 4,002nd Martian day, or sol, of the mission. The rover captured its own shadow shifting across the surface of Mars using its black-and-white Hazard-Avoidance Cameras, or Hazcams.

Instructions to record the videos were part of the last set of commands beamed up to Curiosity just before the start of Mars solar conjunction, a period when the Sun is between Earth and Mars. Because plasma from the Sun can interfere with radio communications, missions hold off on sending commands to Mars spacecraft for several weeks during this time.

The first looks forward, into Gediz Vallis, where Curiosity will eventually travel. The second looks back down Mt Sharp and out across the rim of Gale Crater.
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Mapping the major lava flood events in Mars’ volcano country

The volcanic events in Mars' volcano country
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In a paper just released, scientists have used the orbital data from Mars Reconnaissance Orbiter (MRO) to map on Mars forty different past volcanic eruptions of extensive flood lava covering large regions, all within the region I dub “volcano country” because its entire surface seems mostly shaped by flows of lava.

The map above, figure 1 from the paper, shows the study area (within the white rectangle), with its global context and additional information added by me on the right. Most of the largest earthquakes detected by InSight ran from north-to-south down the center of the white box. The named features are all large flood lava events, with the youngest being Athabasca. Within the Cerburus Plains feature the researchers mapped many smaller events which brought the total up to forty. From the abstract:

An area almost as large as Europe was investigated. The study revealed the products of more than 40 volcanic events, with one of the largest flows infilling Athabasca Valles with a volume of 4,000 km3. The surface appearance and material properties suggest that Elysium Planitia is composed of basalt, the most common type of lava on Earth. The area also experienced several large floods of water, and there is evidence that lava and water interacted in the past. However, while there could be ice in the ground today, it likely occurs in small patches.

None of these flood lava events involved the gigantic volcanoes that surround this region. Instead, the lava erupted from vents within this region, and then flowed downgrade to flood large areas, sometimes covering over parts of earlier lava floods. All also flowed much faster than lava on Earth, flooding vast regions — comparable to entire countries — often in mere weeks.

Juno’s closest image of Europa suggests recent surface activity

Juno's best image of Europa
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Analysis by scientists of the closest image of Europa taken during Juno’s close-fly on September 29, 2022 suggests that a particular strange feature, dubbed the “platypus” due to its shape, might be very young and indicate recent surface activity that could be related to underground liquid water.

That picture, reduced and sharpened to post here, is to the right. It is figure 2 of the paper. The description of this photo from the abstract:

Intricate networks of cross-cutting ridges and lineated bands surround an intriguing 37 km (east-west) by 67 km (north-south) chaos feature with a concentric fracture system, depressed matrix margins, and low-albedo materials potentially associated with brine infiltration. The morphology and local relief of the chaos feature are consistent with formation in the collapse of ice overlying a salt-rich lens of subsurface water. Low-albedo deposits, similar to features previously associated with hypothesized cryovolcanic plume activity, flank nearby ridges. The SRU’s high-resolution view of many types of features in a single image allows us to explore their regional context and greatly improve the geologic mapping of this part of Europa’s surface. The image reveals several relatively youthful features in a potentially dynamic region, providing baselines for candidate locations that future missions can investigate for present day surface activity.

SRU is Juno’s Stellar Reference Unit camera, designed to take pictures using only the low light of Jupiter reflected onto nighttime surfaces of Jupiter’s moons. It took this photo when Juno was only 256 miles above the surface.

This feature will obviously become a prime target for Europa Clipper when it arrives into orbit around Jupiter in April 2030. From this vantage point — safer than continuous exposure to Jupiter’s magnetosphere while in orbit around Europa — the spacecraft will do 44 close-flys of the moon.

Isolated mesa on Mars

An Isolated mesa on Mars
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The central butte is about 100 feet high. Not only are its flanks terraced, suggesting sedimentary layers, note the many black dots on its northern slopes. Those dots appear to be many boulders that appear to have rolled down the slopes to settle mostly near the mesa’s base.

The boxwork ridges to the west and south suggest the ground was fractured in some event to produce cracks, which were later filled with material that was erosion resistent. As the terrain was worn away by wind it left these ridges behind.

The prevailing winds in this region are believed to blow mostly to the south, which might explain the parallel ridges south of the mesa. Or not. On this I am guessing entirely.
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Curiosity takes a close-up of distant cliffs

Panorama on December 20, 2023
Panorama on December 20, 2023. Click for full image.

Close-up of a distant cliff
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Cool image time! The picture to the right, reduced and sharpened to post here, was taken on December 21, 2023 by the chemistry camera (ChemCam) on the rover Curiosity. Originally designed to take close-ups of rocks very nearby the rover, the science team over time discovered that they could also use this camera to get close-ups of very distant objects, providing them another way to study the geology in Gale Crater and on Mount Sharp.

The picture to the right I think shows the horizon area indicated by the arrow on the panorama above, taken the day before. Note the many many layers, a geological feature that Curiosity has discovered is ubiquitous on Mars. Over eons the entire surface of the red planet has been layered repeatedly by cyclical geological events, producing layers within layers within layers. I guarantee that when Curiosity gets closer to this cliff it will see layers inside the smallest layers ChemCam can see now.

The red dotted line on the panorama above indicates the approximate planned route that Curiosity will eventually take, cutting across in front of that mountain and turning south somewhere near but to the west of where the cliff in this picture is located.
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A glacial lake on Mars?

A glacial lake in a
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It shows what appears to be a glacial flow of ice, flowing downhill to the southwest and inside a wide canyon about three miles across. The canyon rims to the north and south are about 2,000 to 2,100 feet above the canyon’s lowest point, indicated by the string of “+” signs.

This close-up view immediately suggests a canyon whose glacier flows outward to the southwest into open lowland terrain, though the three craters, because they are undistorted, suggests that this flow is presently not active. That suggestion however would be wrong. It is always necessary to understand Martian geology to not only take close-in views at high resolution, but to zoom back and see the terrain in context.
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Ingenuity’s engineers explain what they have learned flying the helicopter on Mars

Link here. The essay details carefully the problems they have faced, and how they have not only overcome them but used them to refine operations to squeeze far more capabilities out of the helicopter, beyond its initial design.

Saving flight time saves energy, reduces heating, and provides more freedom to use slower speeds to tiptoe around disruptive terrain that might otherwise endanger or significantly degrade the landing accuracy of the helicopter. Higher speeds and higher accelerations reduce the time needed to execute a given flight path. Higher altitudes permit higher speeds, as the wider field of view helps to keep ground features in view of Ingenuity’s navigation camera longer, counteracting the effect of increased speed. Expanding Ingenuity’s flight envelope had the potential to relax flight planning constraints and allow Ingenuity to operate more effectively alongside Perseverance.

As a result, beginning with flight 45 the team has made changes to increase flight speeds and acceleration at every point of every flight, thus allowing the helicopter to fly higher and farther with less strain.

This report however does not provide any information on Ingenuity’s last two flights, especially its 68th, which did not go as planned. The helicopter appears to be in good shape (the team has already planned the 69th flight, which was supposed to happen two days ago), but a more detailed update would be appreciated.

Glacial layers in Mars’ glacier country

Glacial layers in Mars' glacier country
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 20, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It features a 250-foot-high north-south cliff that appears to have numerous horizontal layers within it.

Moreover, both on the plateau above the cliff as well as the floor below it, the entire surface seems to resemble a thick snow/ice field, made even more evident by the distortion of many craters and the apparent glacial material inside each crater.

The layers suggest that this ice was laid down in a series of cycles. During cold periods snow fell and accumulated as ice over time. When things became warmer some of that ice sublimated away, but not all. With the next cold cycle a new layer was put down.

The many layers suggest many climate cycles on Mars, none of which were caused by SUVs or coal-firing electrical power stations.
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A land of buttes on Mars

A land of buttes on Mars
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 4, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled a “terrain sample” by the science team, it was likely shot not as part of any specific research project but to fill a gap in the schedule so as to maintain the camera’s proper temperature. When the camera team has to do this they try to pick targets that are of some interest. Usually they succeed, considering the enormous gaps we presently have of Mars’ geological history.

This picture is no different. It shows a land of buttes and mesas, all ranging from 20 to 200 feet high, surrounded by canyons filled with ripple dunes of Martian dust. If you look at the floor of those canyons closely, you will notice that where there are no ripple dunes the ground is slightly higher and smooth. It is as if that ground was a kind of sandstone that was eroded away by wind into sand, which then formed the dunes.
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Another minor canyon on Mars that would be a world wonder on Earth

Another minor canyon on Mars
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 6, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the steep north canyon wall of one small part of the Martian canyon complex dubbed Noctis Labyrinthus

The elevation drop in this picture is about 8,000 feet, but the canyon’s lowest point is several miles further south and another 7,000 feet lower down. What is most intriguing about the geology here is its age. If you look at the full resolution image, you will see that there are scattered small craters on the smooth slopes that resemble sand that gravity and wind is shaping into those long streaks heading downhill.

Those craters, however tell us that these smooth slopes are very old, and have not changed in a long time. Furthermore, though the material appears to look like soft sand, the craters also tell us it long ago hardened into a kind of rock. If wind is shaping this material, it must be a very slow process.

The light areas on the rim as well as the ridge peaks below the rim suggest the presence of geological variety, which fits with other data that says Noctis Labyrinthus has a wide variety of minerals.
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Perseverance looks at Jezero Crater in high resolution

Perseverance's future route
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The Perseverance science team earlier this week released a mosaic taken by the rover’s high resolution over three days in November, showing the entire 360 degree view of Jezero Crater from where Perservance sat during the month long solar conjunction that month, when communications with Mars was cut off due to the Sun being in the way.

Part of that panorama, significantly reduced, cropped, and enhanced, is posted above, focusing on the western rim of Jezero Crater and the route that Perseverance will likely take in the future. Below is an overview map that indicates by the yellow lines the approximate area covered by this picture. The light blue dot marks Perseverance’s present location, while the dark blue dot marks where it took the mosaic and was also stationed during that solar conjunction. The dotted red line on both images marks the approximate proposed route that the science team is considering for leaving Jezero crater. Instead of going out through Neretva Vallis, they are instead considering heading south to go over the crater’s rim itself.

Ingenuity’s present position is marked by the green dot. This is where it landed after flight 67 on December 2nd. On December 8th the helicopter’s engineering team had released the flight plan for flight 68, scheduling it for December 9th, but as of this date it appears that flight has not occurred. I suspect the delay is because communication between Ingenuity and Perseverance is presently spotty, though the Ingenuity team has released no information.

Overview map
Click for interactive map.

The end of a 400-mile-long Martian escarpment

The end of a 400-mile-long escarpment
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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on August 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter. It shows the cracked top of a enscarpment, with the bottom point to the west about 2,400 feet lower in elevation.

The north-south cracks at the top of the cliff indicate faults. They also suggest that the cliff itself its slowly separating from eastern plateau. North from this point, beyond the edge of this picture, are several places where such a separation has already occurred, with the collapsed cliff leaving a wide pile of landslide debris at the base.

This cliff actually continues north for another 400 miles, suggesting that the ground shifted along this entire distance, with the ground to the east going up and ground to the west going down. Because the cliff is such a distinct and large feature, it has its own name, Claritas Rupes, “rupes” being the Latin word for cliff.
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Stripped screws preventing access to Bennu samples

According to the scientists working to extract the samples from the asteroid Bennu brought back by the OSIRIS-REx sample return capsule, the work has been stymied because of two stripped screws.

Last month, researchers at the Johnson Space Center in Houston, Texas, discovered that two of the 35 screws that fasten the lid of the sample-return canister couldn’t be opened — blocking access to the remainder of the space rock. Curators used tweezers to pull out what they could, but NASA is now making new screwdrivers so it can get into the equipment it flew billions of kilometres across the Solar System to the asteroid Bennu and back.

Because the capsule is kept within a sealed glovebox to prevent the samples from being contaminated by the Earth environment, removing the screws requires NASA to manufacture special screwdrivers that will also not contaminate that environment. This work is what is causing the delay.

Martian crater or mud caldera?

Martian crater or volcano?
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists only call this a “feature,” likely because they don’t wish to guess as to its nature without more data. However, the 2.5 mile wide splash apron around the central double crater certainly merits a closer look. That double crater could be from impact, but it also could be a caldera, with the apron the result of material that flowed from the caldera.

That there appear to be fewer craters on the apron than on the surrounding terrain strengthens this last hypothesis. The apron would have erased many earlier impact craters, resulting in this lower count.

The location however suggests that if this feature was volcanic in origin it might not have been spewing out magma.
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Craters in a row

Craters in a row
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Cool image time from Mars! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It highlights a string of craters, all lined up in an almost straight line.

Were these craters caused by the impact of an asteroid that broke up as it burned its way through the thin Martian atmosphere? The lack of any raised rims argues instead that these are sinks produced not from impact but from a collapse into a void below, possibly a fault line.

Yet, almost all of the craters in this image, even those not part of this crater string, show no raised rims. If sinks, the voids below don’t seem to follow any pattern, which once again argues in favor of random impacts, with the string produced by a bolide breaking up just prior to hitting the ground.
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The steep mountain slopes inside Valles Marineris

Overview map

The steep mountain slopes inside Valles Marineris
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Time for another cool image showing the dramatically steep terrain of Valles Marineris on Mars, the largest known canyon in the solar system. The picture to the right, cropped, reduced, and enhanced to post here, was taken on October 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists rightly label this picture “Steep Slopes in West Melas Chasma”. The red dot marks the high point on this ridgeline. The green dot at the upper left marks the lowest point in the picture, about 4,800 feet below the peak. The blue dot on the right edge marks the low point on the ridge’s eastern flank, about 4,600 feet below the peak. The cliff to the east of the peak drops quickly about 1,300 feet in less than a mile.

On the overview map above, the white dot marks the location. The inset is an oblique view, created from a global mosaic of MRO’s context camera images, with the white rectangle indicating approximately the area covered by the picture above.

The immense scale of Valles Marineris must once again be noted. The elevations in this picture are comparable to the descent you make hiking down from the South Rim of the Grand Canyon. They pale however when compared to Valles Marineris. In the inset I have indicated the rim and floor of Valles Marineris in this part of the canyon. The elevation distance between the two is 18,000 feet.

In other words, the canyon to the east of this ridge is quite comparable in size to the Earth’s Grand Canyon, and it is hardly noticeable within the larger canyon of Valles Marineris.

Big Martian gullies partly filled with glacial material

Overview map

Big Martian gullies partly filled with glacial material

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists dub as “large gullies with infilled alcoves.”

Gullies on Mars were one of the first discoveries by orbiters of small-scalle potential water-caused features on the Red Planet. The favorite explanation for their formation today involves the seasonal freeze-thaw cycle, combined with the deposition of ice and dry ice frost in the winter. When that ice and dry ice sublimates away in the spring it causes collapse and erosion, widening the gullies.

These gullies also exhibit evidence that underground and glacial ice might contribute as well. The material in the largest gullies looks like a mixture of glacial material and dust and debris. It could also be that there is ice impregnated in the ground, which can cause large collapses when it sublimates away.

The white rectangle on the overview map and inset above marks the location of this picture, on the western rim of a 13-mile-wide unnamed crater inside the western portion of the 2,000-mile-long mid-latitude strip on Mars I dub glacier country, since every image from orbit shows evidence of glaciers.

This picture is no different, as the horizontal cracks at the base of the crater rim suggests the glacier that fills the crater floor is being pulled apart by gravity at its edges. The elevation drop from the top of the rim to the floor is about 3,200 feet, so any ice on that slope will definitely be stressed by gravity. Such cracks are therefore not surprising.

Psyche takes its first pictures

The spacecraft Psyche — going to the metal asteroid Psyche — has successfully taken its first pictures, proving its camera and pointing system work as planned.

The pictures, taken on December 4, 2023 from about 16 million miles from Earth, are actually quite boring, merely showing a field of stars. However,

The imager instrument, which consists of a pair of identical cameras, captured a total of 68 images, all within a star field in the constellation Pisces. The imager team is using the data to verify proper commanding, telemetry analysis, and calibration of the images. …The imager takes pictures through multiple color filters, all of which were tested in these initial observations.

At this moment all looks good for Psyche’s eventual arrival at Psyche in 2029.

Lava-filled Martian crater

Lava-filled Martian crater
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the northeast corner of an unnamed 7-mile-wide crater, located near the equator in the dry Martian tropics.

The MRO science team labels this “crater and lava fill”, suggesting that the crater interior is filled with lava material. The nature of that crater floor reinforces this conclusion, as it is relatively smooth and does not have rough aspects of glacial material found in craters in the mid-latitudes. Instead, it looks like a frozen lake of lava that has the peaks of mostly buried features poking up at various spots.

What makes this crater interesting however are the gullies on the northern interior rim. Gullies on Mars are normally thought to be associated with some water-frost-ice process, probably seasonal, where the thaw-freeze cycle causes small collapses and avalanches. Yet, this crater is almost at the equator, in a very dry region where no evidence of near-surface ice is found. Gullies here suggest the hypothesis for explaining the gullies on Mars have not quite solved the mystery.
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Thick windblown ash in Mars’ largest mountain region

Thick windblown ash near Mars' largest volcano
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The cool image to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what the scientists label as “Erosional Features on Olympus Mons.”

What is eroding? Based on the picture itself the first guess is volcanic ash, as these features strongly resemble the many features seen in the Medusae Fossae Formation, the largest volcanic ash field on Mars — about the size of the subcontinent of India.

Medusae however is many thousand miles away, and is not apparently related to any specific volcano. These features are instead directly linked to Olympus Mons, the largest known volcano in the solar system. However, much of the terrain for many hundreds of miles around Olympus is covered with flood lava, which was deposited and hardened quickly to form smooth featureless plains that have resisted much erosion over the eons. Here the terrain is clearly eroded, which suggests that if the material here is volcanic, it was laid down not by flood lava but by falling ash that got compressed but was easily friable and could be blown away by the winds of Mars’ thin atmosphere.
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Close-up of Helene, one of Saturn’s many many moons

Helene, as seen by Cassini in 2011
Helene, as seen by Cassini in 2011

Cool image time! Though the Saturn orbiter Cassini is long gone, having been sent into Saturn’s atmosphere to burn up in 2017, its image archive of magnificent pictures is still available to peruse. To encourage others to do so, NASA today issued a series of press releases, listing the spacecraft’s top ten pictures from 2011, 2012, 2013, 2014, and 2015.

The picture to the right, cropped, reduced, and sharpened to post here, comes from the 2011 collection and was taken on June 18, 2011. It shows a close-up of 21-mile-wide Helene, one of Saturn’s many many moons and only discovered in 1980. Back in 2010 I featured another Cassini image of Helene, but that picture did not reveal the small surface features seen in the photo to the right.

The light and dark streaks probably indicate dust flowing downhill on the surface. Though the gravity of this object is tiny, it will be enough for dust to act like almost like a liquid, flowing down grade and then pooling in the central pond at the lowest point near the center of the picture. That process is so much like liquid flowing that it appears to have even eroded gullies on slopes near the top and bottom of the picture.

Side note: NASA’s “Science Editorial Team” also issued a press release today that falsely and ignorantly claimed these releases were “to celebrate 10 years since arriving at Saurn,” implying that Cassini arrived in 2013 and is still functioning.

The problem is that Cassini arrived in orbit around Saturn in 2004 and as I noted above ended its mission in 2017. It thus appears that the NASA Science Editorial Team is unable to do even one five-second web search to find out what really happened.

Just another data point indicating the dark age we now live in.

British scientists get their own Bennu sample to study

The British History Museum has now received a small sample of material from the asteroid Bennu, brought back to Earth by the planetary probe OSIRIS-REx.

The first two years of research at the Natural History Museum will focus on non-destructive tests, such as X-ray diffraction and electron microscopy to learn about Bennu’s mineral composition and structure. The largest grains in the sample are on the order of millimetres wide, while the smallest are mere dust particles. “It doesn’t sound like a lot of material, but it’s plenty to work with,” King said.

The museum is home to one of the world’s leading meteorite collections, and the staff are well-used to handling small amounts of extremely precious materials from outer space. Unlike meteorites that have been baked and battered on their fiery passage through Earth’s atmosphere, the dust and rocky fragments from Bennu were brought to Earth in pristine condition, allowing scientists a rare glimpse of the unaltered asteroid.

The last sentence says it all. Up until recently, researchers have had a distorted view of the overall make-up of asteroids because the oldest kinds, carbonaceous chondrite, are the most delicate and get significantly changed by their passage through the Earth’s atmosphere. The samples from Bennu and Ryugu are changing this, and will eventually revolutionize the understanding scientists have of our present solar system.

Mars’ giant sinkholes

The floor of one of Mars' giant sinkholes

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small section of the floor and northern slope of Hebes Chasma, one of the many very large enclosed pits that can be found to the north of Valles Marineris, the largest canyon in the solar system. Though Hebes seems small next to the 1,500 mile long Valles Marineris, it still is 200 miles long by 80 miles wide, and could easily fit a half dozen Grand Canyons within it.

For example, the Grand Canyon is from 4,420 to 5,400 feet deep, hiking down from the south and north rim lodges respectively, which sit about ten miles apart. On this picture, the peak on the right sits about 5,300 feet above and only about 3.8 miles from the low spot on the bottom left, which means this one small picture encapsulates the Grand Canyon. And yet, the northern rim of Hebes sits another 21,000 feet higher and twelve miles away. And the entire chasma itself extends 50 miles to the west, 150 miles to the east, and 50 miles to the south.
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Striped terrain on Mars

Overview map

Striped terrain on Mars
Click for original image.

Today’s cool image will be a mystery with the answer below the fold. Before you look at the answer, however, you must try to come up with your own explanation for the picture to the right, cropped to post here, that was taken on September 25, 2018 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

What we see in this picture is what looks like a striped terrain, alternating bands of light and dark. What caused the bands? Why the different colors?

The overview map above provides some clues. The white rectangle inside Juventae Chasma near the map’s center marks the area within which this picture was taken, though the picture to the right covers only about a pixel inside that rectangle.

Can you guess what these stripes reveal, from this little information? For this quiz to work you must make a guess, but be prepared to be wrong and quickly reassess your conclusions. Such is the real scientific method, so rarely taught now in schools.
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Martian ice sheets sublimating like peeling paint?

Overview map

Martian ice sheets resembling paint peeling
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The features are described as “ribbed terrain” in the label. To my eye they more resemble flakes of peeling paint, most especially the mesas in the lower left. On the full image there are many more examples that resemble old paint peels, barely attached to the wall.

The white dot on the overview map above marks the location, deep inside the 2,000-mile-long strip in the northern mid-latitudes I dub glacier country, because everything seems covered by glacial features. This location is at 42 degrees north latitude, where plenty of near-surface ice features are found on Mars.

At first glance it looks like the top “paint-peel” layers to the south have been slowly sublimating away, leaving behind the smooth plain to the north. The problem is that this smooth area in the full image actually appears to be a glacial ice sheet of its own, filling all the low areas between mesas.

In other words, we are probably looking at layers and layers of ice sheets, each created during a different Martian climate cycle, caused by the wide swings of the planet’s rotational tilt, or obliquity.

The location is within Arabia Terra, the largest transitional zone on Mars between the northern lowland plains and the southern cratered highlands. Thus it sits above the glaciers that fill the lower regions of chaos to the north. What we have here is terrain that will eventually become chaos terrain, as the narrow faults and cracks are slowly widened into canyons by the cycles of glacial activity.

Ancient volcanic vent on Mars

Volcanic vent on Mars
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 28, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture label describes it as a “Low Shield Vent and Pit Northeast of Arsia Mons,” suggesting these depressions are volcanic in nature. We know the pit in the lower left is not an impact crater because it has no raised rim of ejecta. Instead, it looks like a collapsed sinkhole, formed when the ceiling above a void could no longer support its weight. Similar, the trench to the northeast is aligned with the downhill grade to the northeast, with its features suggesting a vent draining in that direction.

The ample dust inside the trench and pit suggest that it has been a very long time since this vent was active. Research suggests volcanic activity last occurred in this region from 10 to 300 million years ago, so that gives us a rough estimate of this vent’s age. Since then any dust that is blown into it will tend to become trapped there.
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The southernmost extent of Mars’ youngest lava flood event

The southernmost edge of Mars' youngest lava event
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Labeled “flow margin in Elysium Planitia,” it shows the very edge of what scientists believe was the most recent large lava event on Mars, dubbed the Athabasca Valles, that is thought to have occurred only 600 million years ago. In only a matter of weeks the fast flowing lava covered a region about the size of Great Britain. What we see here is the southernmost edge of that flow, with the smooth terrain on the west an older lava flood plain, covered by the new flood lava from Athabasca on the east.

The polygon cracks likely indicate cracks that formed during the hardening process (like the polygon cracks in drying mud). Hot lava then pushed up from below to form the ridges. It is also possible the ridges are what scientists call “wrinkle ridges,” formed when material shrinks during the drying process.
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Salt glaciers on Mercury?

From Figure A1 of paper
From Figure A1 of paper.

Based on a new analysis of data from the Messenger spacecrat that orbited Mercury from 2011 to 2015, scientists today posited the possibility that salt glaciers exist on Mercury and have reshaped its terrain in manner vaguely comparable to what Mars Reconnaissance Orbiter (MRO) has found on Mars.

You can read the paper here [pdf]. The image to the right, enhanced by the scientists to bring out the faint blue in the hollows, is remarkably reminiscent of the hollows and scallop terrain found in many places in the high Martian latitudes. From its conclusion:

Detecting widespread elemental volatile surface compositions, ubiquitous sublimation hollows, and extensive chaotic terrains has significantly reshaped our perception of Mercury’s geological past. These observations collectively point to the presence of volatile-rich strata spanning several kilometers in depth and likely formed before the [Late Heavy Bombardment] (∼3.8 billion years ago). This notion challenges the conventional view of a volatile-depleted Mercurian crust.

The morphologies within Mercury’s Raditladi basin bear a striking morphologic resemblance to glaciers on Earth and Mars, suggesting their origin from an impact-exposed [volatile-rich layer], likely containing halite. Our numerical simulations show that the unique rheological properties of halite, including the high thermal sensitivity of its viscosity, reinforce this hypothesis. These glacier-like features occur beyond the chaotic terrain boundaries, indicating a potentially global yet concealed, volatile-rich upper stratigraphy. We posit that the exposure of these volatile-rich materials, instigated by impact events, could have been instrumental in the formation and evolution of hollow features, signifying a complex geodynamic history of volatile migration and redistribution, essentially interconnecting some of the oldest and youngest stratigraphic materials on the planet.

The scientists do not have enough information as yet to determine if these glaciers are still active or not. Moreover, the theorized layer of volatile material near the surface remains unconfirmed, requiring in situ investigation to determine its existence with certainty. Like Mars, if it exists it likely only does so in the high latitudes.

Lava/ice eruptions on Mars

Lava/ice eruptions on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled by the science team as showing “possible lava-ice interaction,” the photo features some pimply-looking mounds that, though round like craters, sit above the surrounding landscape like small volcanoes.

That these are likely not ancient pedestal impact craters that now sit higher because their material is packed and can resist erosion is illustrated by the bridge-like mound in the lower right. This mound was likely once solid, but its north and south sections have disappeared, either by erosion or sublimation. If formed by an impact the mound would have had a depression in its top center, and would have only eroded outside the rim.
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