Astronomers think they have completed the census of Near Earth asteroids

Astronomers in a new paper [pdf] have concluded that the census of Near Earth asteroids is largely now complete, and have begun focusing their effort on narrowing down the list of potentially dangerous asteroids in that census. From the press release:

Researchers from CU Boulder and NASA have completed a census of hundreds of large asteroids orbiting near Earth—gauging which ones could come precariously close to our planet over the next thousand years. The researchers identified at least 20 asteroids that scientists may want to study more to make certain they pose no threat to life on Earth in the next millennium.

To be clear, the researchers say the odds of any of these rocky bodies striking the planet are extremely low, and are next to zero for the coming century. But because the fallout from such an impact would be catastrophic, it’s important to be sure, said Oscar Fuentes-Muñoz, lead author of the study. “We don’t want to alarm people, because the results are not alarming,” said Fuentes-Muñoz, a doctoral student in the Ann and H.J. Smead Department of Aerospace Engineering Sciences. “But there are a lot of uncertainties in predicting so far into the future.”

To sum up, none of those 20 asteroids has any chance of hitting the Earth in the next few hundred years. Beyond that the uncertainties make it difficult to predict. Reducing those uncertainities is now the focus of their work.

Avalanche to the east of Gale Crater on Mars

Landslide on Mars
Click for original picture.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an avalanche that slumped downward out of the material that forms the interior western wall of an unnamed 25-mile-wide crater about 100 miles east of Gale Crater, where Curiosity has been roving for more than a decade.

The scientists call these types of Martian avalanches “mass-wasting events”, since the entire mass of the cliff moves downhill in a chunk, rather than as a pile of rocks that grows in size and strength as it picks up material on its way down.

It is not clear how old this slide is. A lot of the material on this slope appears to be Martian dust, some of which has flowed into the avalanche material after it had slide downhill.
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Shadowcam on South Korea’s Danuri lunar orbiter sees no obvious ice in the permanently shadowed interior of Spudis crater

Overview map

Using Shadowcam, a camera built by Arizona State University that is on South Korea’s Danuri lunar orbiter and is designed to see into very dark regions of little light, scientists have obtained optical images showing the permanently shadowed interior of Spudis Crater, located only about ten miles from the Moon’s south pole.

That picture is below. To the left is an annotated overview created from Lunar Reconnaissance Orbiter (LRO) high resolution images. The white box inside Spudis Crater indicates the area covered by the section of the Shadowcam image I have focused on. The red outlines indicate areas that are thought to be permanently shadowed. The relatively flat ridgeline between Shackleton and Spudis is one of the prime future landing sites for NASA’s Artemis program.
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Martian rootless cones

Rootless cones
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 8, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team labeled this picture simply “Rootless Cones,” which is a feature that is created when the lava that covers the surface is thin, allowing the heated material below (which is not lava) to burst upward, producing the cone and caldera. If you look at the full image you will see other similar clusters of cones scattered about on this very flat and featureless plain. Apparently, the material that this lava plain covered had several similar bursts in a number of areas.

Such cones in this particular lava field are not rare, and in fact are evidence that this particular field is young.
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ESA to live-stream image downloads from Mars Express

To celebrate Mars Express’s 20th year in orbit around Mars, the European Space Agency (ESA) has announced that tomorrow it will for one hour live-stream the image downloads coming from the orbiter.

I have embedded that live stream below. According to the press release, new images will arrive about once every 50 seconds. The camera that will be taking the pictures however is not one of Mars Express’s main instruments, but designed instead to simply monitor the separation of the Beagle-2 lander from the orbiter in 2003. Since 2007 however the science team has used its low resolution global images of Mars for public relations, education, and even some science research.

That the science team is not providing the live feed from its high resolution camera however illustrates why Mars Express gets so little press coverage, compared to Mars Reconnaissance Orbiter (MRO). All MRO images are released to the public, usually only a month or so after they reach Earth. The ESA however has never made the archive of Mars Express accessible, as far as I have been able to discover. All it does is periodically issue a press release about once every few months touting one new image, even though the spacecraft is taking dozens daily.
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A typical glacier, on Mars

Overview map

A typical glacier, on Mars
Click for original image.

The cool image from Mars to the right, rotated, cropped, reduced, and sharpened to post here, provides us a good illustration of the lineated grooves that are typically seen on the surface of valley-confined glaciers, both on Earth and on Mars, and are also seen on the patched, grooved surface of Ganymede.

The picture was taken on March 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what appears to be a glacier flowing through a constriction. The arrow indicates the direction of the downhill grade.

The location, indicated by the white dot inside the inset on the overview map above, marks the location, in the western end of the 2,000 long northern mid-latitude strip on Mars I dub glacier country. In these three mensae regions (Deuteronilus, Protonilus, and Nilosyrtis) of chaos terrain practically every high resolution image shows features that resemble glaciers.

In this case, the glacial flow appears to be draining from a 10-mile-wide ponded circular valley though a narrow gap.

The grooved surface of Ganymede

The grooves of Ganymede
Click for original image.

Cool image time! The picture to the right, reduced to post here, was taken on June 7, 2021 when the Jupiter orbiter Juno did a close flyby of the moon Ganymede, taking four pictures.

Citizen scientists Gerald Eichstädt and Thomas Thomopoulos have now reprocessed parts of those images to bring out the details more clearly (the other new versions available here, and here).

I have chosen to highlight the picture to the right however because it so clearly shows the puzzling grooves that cover much of Ganymede’s surface. While these parallel grooves in many ways mimic the grooves often seen on top of valley glaciers on Earth and Mars, on Ganymede they do not follow any valley floor. Instead, they form patches of parallel grooves that travel in completely different directions, depending on the patch. At the moment their origin is not understood.

These grooves are one of the mysteries that Europe’s Juice probe will attempt to solve when it arrives in orbit around Jupiter in 2031.

Webb detects large water plume released from Saturn’s moon Enceladus

Water vapor plume seen by Webb
Click for original image.

Using the infrared cameras on the Webb Space Telescope, astronomers have detected a surprisingly long and large plume of water vapor erupting from the tiger stripe fractures on Saturn’s moon Enceladus that scientists for years have detected vapor plumes.

The false color image to the right shows that plume.

A water vapor plume from Saturn’s moon Enceladus spanning more than 6,000 miles – nearly the distance from Los Angeles, California to Buenos Aires, Argentina – has been detected by researchers using NASA’s James Webb Space Telescope. Not only is this the first time such a water emission has been seen over such an expansive distance, but Webb is also giving scientists a direct look, for the first time, at how this emission feeds the water supply for the entire system of Saturn and its rings.

…The length of the plume was not the only characteristic that intrigued researchers. The rate at which the water vapor is gushing out, about 79 gallons per second, is also particularly impressive. At this rate, you could fill an Olympic-sized swimming pool in just a couple of hours. In comparison, doing so with a garden hose on Earth would take more than 2 weeks.

Though that rate of release sounds large, we must remember it is being released from a moon 313 miles across. From that perspective the rate of flow is quite reasonable.

Cracking pedestal crater near Mars’ north pole

Cracking pedestal crater near Mars' north pole
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also rotated it so that north is to the top.

Labeled a “terrain sample” by the camera team, this picture was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule so as to maintain its proper temperature. As usual, when the camera team needs to do this, they try to pick a target of interest. Sometimes they succeed, sometimes not.

In this case, the picture is of a location only about 800 miles from the Martian north pole, on the northern lowland plains. While the section shown to the right focuses on the largest crater, the full picture includes a few others, all of which appear to have their interior floors cracking in the same way, and all appear to be pedestal craters, sitting above the surrounding terrain, though by not as much.
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China unveils next Shenzhou launch date and crew to its space station

China today revealed the next three-man crew to occupy its Tiangong-3 space station, with a planned launch in a Shenzhou crew capsule targeting May 30, 2023, Chinese time.

Because of time differences, that launch will occur tonight at 6:28 pm tonight, Pacific time. The rocket will be a Long March 2F taking off from China’s western interior Jiuquan spaceport. The rocket’s lower stages will therefore crash somewhere in China.

The crew will remain on board the station for five months, and with one astronaut the first Chinese to fly in space four times.

A fractured spot in Mars’ northern lowland plains

A fractured spot in Mars' northern lowland plains
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 16, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a pockmarked flat plain with a scattering of meandering hollows, each filled with ripple sand dunes that make these depressions resemble at first glance the tracks of tires.

Obviously, we are not looking at evidence of a past giant vehicle moving across the ground on Mars. The MRO science team labels these “fractures,” suggesting some past geological process caused the surface to crack in this manner, with those cracks widening with time due to erosion or sublimation.

The location of course tells us something about that process.
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The eroding north wall of glacial-filled Harmakhis Valles

The north wall of Harmakhis Valles
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on February 8, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

We are looking at the 2,400-foot-high cliff, its lower walls clearly cracking horizontally as they sag downward, with other large sections higher up appearing to have been eroded away in larger pieces.

Yet, the ground below this cliff wall appears to have no debris piles, the kind you would expect below a landslide. Instead, that ground appears to be very glacial in nature, with many linear parallel lines suggesting layers.

The overview map below provides us the context, and an explanation as to where that debris has gone.
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Knobs on the floor of a Martian caldera

Knobs on the floor of a Martian caldera
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows what the scientists have dubbed as “enigmatic knobs” located on the caldera floor of a Martian shield volcano.

The knobs themselves, while puzzling, aren’t that interesting on their own. They are no more than 100 to 200 feet high, and are relatively featureless. Since most lack a pit at their peaks, they are probably not some form of small volcanic vent, though this conclusion is uncertain. The location, at about 30 degrees south latitude, suggests the faint possibility of near surface ice, which could make these mud volcanoes, or a very specific Arctic-type permafrost mound dubbed pingos, but once again the lack of any central pit at their peaks makes these origins also doubtful.

What the knobs however revealed to me was a giant Martian shield volcano I had never noticed before, even though it was hiding in plain sight.
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Frozen waves of Martian lava?

Frozen waves of Martian lava?
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this a terrain sample image, which implies it was taken not as part of any specific request, but to fill a gap in the camera’s schedule in order to maintain its proper temperature.

What are we looking at? This stippled terrain with curved ridges actually extends quite a distance beyond this image. A MRO context camera picture taken on July 22, 2020 shows its full extent, about 10 miles wide but extending to the north and south about 30 miles total, butting up against a north-south mountain chain to its east that is about seventy miles long with its highest peak about 8,000 feet above this plain.
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Lunar Reconnaissance Orbiter spots Hakuto-R1 impact debris on Moon

Hakuto-R1 impact site, before and after
Click for original blink image.

NASA’s Lunar Reconnaissance Orbiter (LRO), scientists have spotted what they think is the impact debris produced when Ispace’s private lunar lander Hakuto-R1 crashed on the Moon on April 25, 2023.

To the right are two LRO images, the first at the top taken prior to Hakuto-R1’s landing attempt. The second at the bottom was acquired by LRO on April 26, 2023, the day after that attempt. The lettered arrows indicate four spots where the scientists identified changes between the two pictures. From the caption:

Arrow A points to a prominent surface change with higher reflectance in the upper left and lower reflectance in the lower right (opposite of nearby surface rocks along the right side of the frame). Arrows B-D point to other changes around the impact site.

According to the LRO science team, these changes suggest different pieces of debris, though it will take more analysis and more images under different lighting conditions to determine more precisely what they have found.

The presence however of four pieces strongly suggests that Hakuto-R1 hit the ground hard enough to break apart. Based on the initial data received during landing, it was thought the spacecraft had touched down softly but then was damaged by some unforeseen obstacle on the ground, such as a large boulder. The LRO image suggests instead that it did not touch down softly at all.

Ancient volcano vent in the Martian southern cratered highlands?

Ancient volcano vent on Mars?
Click for original image.

The nature of today’s cool image suggests both ancient and more recent geological activity, each coming from entirely different sources but both helping to shape the alien Martian surface.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on March 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team has labeled an “elongated depression,” sitting in the middle of a relatively flat but very rough stippled circular plain about 60 miles in diameter. An MRO context camera picture, taken on February 19, 2012, covered the central strip of this plain, and shows that its surface is equally rough and stippled everywhere, with only a few craters and one or two slight changes in elevation.

So, how does this feature tell us both about the ancient and recent geological history of this spot on Mars?
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Buried dying glacier in the Martian dry equatorial regions?

Buried glacial ice in dry equatorial regions?
Click for original image.

Today’s cool image from Mars is not so much unique visually as it is unique in terms of its location. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the northern rim of a small crater, with its floor filled with an intriguing mound of material.

The picture was labeled a “terrain sample”, which suggests it wasn’t taken as part of any specific research project by instead to fill a gap in the camera’s schedule. To maintain the camera’s proper temperature, it is necessary to take pictures regularly, and when the camera team finds a gap that is too long, they fill it by choosing some almost random target in that gap that might be interesting. Sometimes it is, sometimes not.

In this case I strongly suspect this target was hardly random. The picture title also mentions MRO’s now retired radar CRISM instrument, which was used to detect evidence of underground ice. My guess is that the camera team thus likely decided to image this crater in high resolution because that radar data suggested the presence of underground ice.

This guess is strongly confirmed by a context camera picture taken of this crater on September 1, 2008. The crater appears surrounded by the typical splash apron one routinely sees around impact craters in the mid- and high-latitude northern lowland plains, where there is a lot of near surface ice.

The bumpy mound seen in high resolution on the floor of this crater could very well be buried glacial ice, as it mimics similar features in the many craters in the mid-latitudes of Mars. But is it buried ice? The location says otherwise.
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Lucy makes course correction in preparation for 1st asteroid fly-by

Lucy's route through the solar system
Lucy’s route through the solar system

The asteroid probe Lucy on May 9, 2023 fired its engines to successfully make a minor course correction in preparation for a fly by of the asteroid Dinkinesh, located in the main asteroid belt between Mars and Jupiter.

Even though the spacecraft is currently travelling at approximately 43,000 mph (19.4 km/s), this small nudge is enough to move the spacecraft nearly 40,000 miles (65,000 km) closer to the asteroid during the planned encounter on Nov. 1, 2023. The spacecraft will fly a mere 265 miles (425 km) from the small, half-mile- (sub-km)-sized asteroid, while travelling at a relative speed of 10,000 mph (4.5 km/s).

Dinkinesh, the white dot inside the main asteroid belt in the lower left of the map to the right, is the first of eight asteroids Lucy will fly past.

Chaos in the southern cratered highlands of Mars

Chaos in the southern cratered highlands of Mars
Click for full image.vi

Today’s cool image takes us to a part of the cratered southern highlands of Mars that I have not featured much previously. The picture to the right, rotated, cropped, and reduced to post here, was taken on March 7, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be a collection of rough hills and mesas surrounded by a sea of smooth ground that at the base of the cliffs seems to end abruptly.

The smooth ground is probably mantled by a layer of dust and debris. Since this location is at 36 degrees south latitude, there is also probably near surface ice under that layer. The abrupt edges likely indicate where the increasing slope next to the mesas and mounds caused that ice to be exposed and thus sublimate away.

As for the location, we must go to the overview map.
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Astronomers discover Earth-sized planet 90 light years away

Using data from a variety of space- and ground-based telescopes astronomers have discovered Earth-sized exoplanet orbiting a red dwarf star 90 light years away.

The exoplanet is dubbed LP 791-18 d, and is thought to be slightly bigger than the Earth. Its orbit, close to the star, causes it to be tidally-locked, with one hemisphere always facing the star. In addition, the presence of another much larger exoplanet in the system causes other tidal effects.

Astronomers already knew about two other worlds in the system before this discovery, called LP 791-18 b and c. The inner planet b is about 20% bigger than Earth. The outer planet c is about 2.5 times Earth’s size and more than seven times its mass.

During each orbit, planets d and c pass very close to each other. Each close pass by the more massive planet c produces a gravitational tug on planet d, making its orbit somewhat elliptical. On this elliptical path, planet d is slightly deformed every time it goes around the star. These deformations can create enough internal friction to substantially heat the planet’s interior and produce volcanic activity at its surface. Jupiter and some of its moons affect Io in a similar way.

The press release makes a big deal about the volcanism, even suggesting it could produce an atmosphere that, because the exoplanet sits on the inner edge of the habitable zone, could make the exoplanet habitable. These speculations are silly, considering the uncertainties, the exoplanet’s evolving orbit, and the star it orbits, and are being pushed mostly because the press office thinks this will be the only way the public will have any interest in the discovery.

While there is an infinitesimal chance there could be life here, a more likely scenario is that it is a lifeless volcano world like Jupiter’s moon Io. Even more probably however is that it is completely different than anything we have yet observed, in ways we can’t yet predict. To find out however we would need close-up observations that will likely not be possible without an interstellar mission.

Final assembly of Chandrayaan-3 begins for launch still targeting mid-July


Click for interactive map.

Engineers at India’s space agency ISRO have begun the installation of the payloads onto its lunar lander/rover, Chandrayaan-3, which is still targeting a mid-July launch.

The map shows the landing location (red dot) near the Moon’s south pole (indicated by the cross). Nova-C is Intuitive Machines private lander, now aiming for a late summer launch at the earliest. Luna-25 is Russia’s first lunar lander since the 1970s, and is also targeting a launch in July.

India’s first attempt, Chandryaan-2, to land a rover at this spot on the Moon failed in 2019. This new mission is essentially a re-do, except that it does not include an orbiter, since the orbiter from Chandrayaan-2 is still operational and can do the job.

All in all, it increasingly looks like the next six months will see a lot of new landing attempts on the Moon.

Alien textured Martian lava

Alien textured Martian lava
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on February 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what the science team labels “regularly textured ground on Pavonis Mons.”

The arrow in the picture indicates the downhill trend. If you look at the full image, you will see that this texture pattern extends in all directions for a considerable distance, both uphill and down, and even covers the entire floor of a depression that appears to contour along the grade instead of going downhill.

The latitude here is very close to the equator. So, even though the elevation is high, being on the slopes of a giant volcano, there is probably no near surface ice here.
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What kind of barred spiral galaxy is the Milky Way?

Three types of barred spiral galaxies
Click for original image.

The uncertainty of science: Though astronomers have long believed that the Milky Way galaxy is a barred spiral galaxy, defined as having a major straight arm coming out in two directions from its nucleus with other spiral arms surrounding it, determining the exact structure has been difficult because of our presence within the galaxy.

The image to the right, taken from a paper just published, shows three different types of barred spirals. On the left is one where the surrounding spiral arms hardly exist. In the center the central bar is surrounded by multiple arms. On the right is a barred spiral with just one major spiral arm.

Though it has been generally accepted that the Milky Way belongs in the center category, astronomers remain unsure about the actual spiral structure. Previous work had suggested the galaxy actually had four major arms, not two as seen by most barred spirals. As noted in the paper, “If that is the case, the [Milky Way] may be an atypical galaxy in the universe.”

The research from the new paper however now proposes that the Milky Way is actually not atypical, but instead more resembles the center image, with two main arms and multiple segmented arms beyond. From the abstract:

Using the precise locations of very young objects, for the first time, we propose that our galaxy has a multiple-arm morphology that consists of two-arm symmetry (the Perseus and Norma Arms) in the inner parts and that extends to the outer parts, where there are several long, irregular arms (the Centaurus, Sagittarius, Carina, Outer, and Local Arms).

The astronomers cheerfully admit that this conclusion is uncertain, and will need many further observations for confirmation.

Brain terrain in and around pedestal crater on Mars

Brain terrain in and around a pedestal crater on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

As I noted in a cool image only two weeks ago, brain terrain is a geological feature wholly unique to Mars that planetary geologists still do not understand or can explain. They know its knobby interweaving nodules (resembling the convolutions of the human brain) are related to near surface ice and its sublimation into gas, but no one has much confidence in any of the theories that posit the process that forms it.

In this case the brain terrain not only fills the crater, it appears to surround it as well, but only appearing at spots where a smooth top layer has begun to break apart. Moreover, the crater appears to be a pedestal crater, whereby much of the less dense surrounding terrain has vanished, leaving the compacted crater sitting higher.
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Glacial sinkhole in the Martian southern cratered highlands?

Overview map

Glacial sinkhole in the Martian southern cratered highlands?
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on February 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). This is a terrain sample image, which means it was snapped not as part of any specific research project but to fill a gap in the schedule in order to maintain the camera’s proper temperature. As usual, the camera team tried to pick something of interest, and I think they succeeded.

The two large depressions in the center of the picture do not resemble impact craters. They have no rim of ejected material and their shape is very distorted. Instead, both appear to be places where a top layer of ice/debris has sublimated away into gas, exposing a lower layer of glacial material that itself is sublimating away to form the bumpy mounds that fill the floor of the depressions.

The white dot inside the inset box on the overview map above marks this location, just south of the northern wall of a large 30-mile-wide canyon, with its northern floor even more depressed, as if the material in that raised middle a flat pile of glacial debris flowing to the southwest after leaving the gap in the crater to the northeast. An MRO context camera picture taken on January 6, 2016 gives a wider view, showing that there are a lot of these type depressions on the surface of this wide middle upraised floor, as well as some obvious impact craters.

This location is in the mid-latitude band where many glacial features are found. In this part of the southern cratered highlands there is also a lot of evidence of top layers sublimating away, as if the glacial material is a large buried ice sheet that is beginning to disappear at places where it has been exposed by impacts or shifting motion. The depression in the picture above appears to be an example.

Engineers free stuck radar antenna on Juice probe to Jupiter’s big moons

Engineers have successfully freed the 52-foot wide radar antenna on the Juice probe to Jupiter, shaking it enough to release a pin that was blocking deployment.

The pin was freed by employing “back-to-back jolts”. Imagine when you roll your car back and forth to get it freed from mud or snow. It appears this is what they did with the pin.

Juice will arrive in Jupiter orbit in 2031, where it will make numerous fly-bys of Europa, Calisto, and Ganymede, and then settle into an orbit around Ganymede alone. The radar antenna was essential for probing the ice content of these worlds, below the surface.

Hat tip to reader Mike Nelson.

Endless dunes amidst Mars’ giant volcanoes

Endless dunes amidst Mars' giant volcanoes
Click for originial image.

Past cool images on Behind the Black showing endless dune fields on Mars have generally focused on two places, the giant Medusae Fossae Formation volcanic ash deposits in the dry equatorial regions of Mars and the Olympia Undae dune sea that surrounds the Martian north pole.

Today’s image to the right, rotated, cropped, reduced, and sharpened to post here, takes us to a completely different dune sea. Taken on February 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), the picture also shows an endless dune sea, though there is faint evidence on those dune fields of buried features, such as the meandering east-west feature in the picture’s center.

This dune sea is also in the dry equatorial regions, like Medusae, but it is much farther east, and sits surrounded by Mars’ biggest volcanoes.
» Read more

Perseverance data suggests a strong river rushed down the delta in Jezero Crater

Skrinkle Haven on Mars
Click for original image.

Based on the images and geology so far gathered by the Mars rover Perseverance as it has climbed up onto the delta that flowed into Jezero Crater sometime in the far past, scientists now think a roaring river once flowed down that delta.

Years ago, scientists noticed a series of curving bands of layered rock within Jezero Crater that they dubbed “the curvilinear unit.” They could see these layers from space but are finally able to see them up close, thanks to Perseverance.

One location within the curvilinear unit, nicknamed “Skrinkle Haven,” is captured in one of the new Mastcam-Z mosaics [a section of which is posted to the right]. Scientists are sure the curved layers here were formed by powerfully flowing water, but Mastcam-Z’s detailed shots have left them debating what kind: a river such as the Mississippi, which winds snakelike across the landscape, or a braided river like Nebraska’s Platte, which forms small islands of sediment called sandbars.

When viewed from the ground, the curved layers appear arranged in rows that ripple out across the landscape. They could be the remnants of a river’s banks that shifted over time – or the remnants of sandbars that formed in the river. The layers were likely much taller in the past. Scientists suspect that after these piles of sediment turned to rock, they were sandblasted by wind over the eons and carved down to their present size.

The press release say nothing about glacial activity here, but I am willing to bet the scientists have considered this. As it requires a greater leap into the unknown, involving geological processes not yet understood on an alien planet, it is makes sense that they have put it aside at this point. I also am willing to bet that it will pop up again, with time and additional data.

Is this ice or lava in the death valley of Mars?

Ice or lava on Mars?
Click for original image.

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

To put it mildly this is strange terrain. The curving east-west feature resembles a glacial flow, but it also has features that say otherwise. For example, what could cause that gap in the middle of the picture? Such things are not usually seen in an ice flow. Then there is that filled crater on the center left edge of the picture, inside the flow. Though filled with material, the flow itself does not flow around the crater, suggesting the impact occurred after the flow. Moreover the crater is a pedestal crater, whereby the surrounding terrain has eroded away so that the crater ends up standing above it.

These facts suggest that this flow is very old, and has not flowed for a very very very long time. This in turn suggests it isn’t ice but solidified lava, though for a lava flow it also has features that are anomalous when compared to typical flood lava on Mars.
» Read more

A rash on Mars

A Martian rash
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The science team labeled this a “Circular Outcrop of Bright Rock.

What I see is a Martian skin rash. Based on the ripple pattern below the ridge one might think we are looking at sand dunes, except that the rash above the cliff has no such pattern. Instead, the ground in this one particular area looks very roughened in a random sort of way.

The location at 27 degrees south latitude suggests there is little near surface ice at this location to cause this feature. The overview map below provides another but not very helpful possibility.
» Read more

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