One Martian ridge among many

One Martian ridge among many
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 30, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is labeled as a “terrain sample,” so it was likely taken not as part of any specific research project but to fill a gap in the camera’s schedule.

The subject this time was a series of parallel ridges. I have cropped the image to focus on the most distinct, which stands at its highest about 600 feet below the dune-filled hollows to the north and south. The streaks on its flanks are likely slope streaks, a phenomenon unique to Mars that is presently not entirely understood. Streaks appear like avalanches, but they do not change the topography at all, and in fact in some cases go up and over rises. It is believed they are related to dust events, but this is not yet confirmed.

Why focus on this ridge however? It isn’t as if this is the most stunning geology on Mars.
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Bursting ice sheets on Mars

Ice sheets on Mars
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on July 31, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample” by the camera team, it was likely taken not as part of any specific research project but to fill a gap in the camera’s schedule in order to maintain its proper operating temperature.

In this case the camera team picked a spot in the northern lowland plains at 39 degrees north latitude. What they got was another great piece of evidence of the existence of a lot of near surface ice on Mars, so much so at this location that the craters have become distorted and blobby. The ice in the ground is unstable enough that nothing here can really hold its shape from season to season and from decade to decade.

As I have noted repeatedly in the past six years, MRO data is proving that Mars is not a dry desert like the Sahara, but an icy desert like Antarctica. Except for the planet’s dry tropics below 30 degrees latitude, Mars appears to have a lot of frozen water available relatively near the surface.
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Mars geology at its strangest

Strange Martian geology
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on July 29, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the northeast quadrant of a weirdly distorted unnamed 3-mile-wide crater in the northern lowland plains of Mars. The crater rim is the ridgeline that enters from picture’s left edge to curve down to exit at bottom right.

The geological feature of interest however is the strange mound to the left of that rim, inside the crater. It certainly appears, based on shadows, that the top of this mound popped off at some time in the past, leaving behind that sharp-edged hollow.

Note however that there is no eruption debris. When a volcano erupts, the debris covers the nearby mountainside. Here we see no evidence of anything that was flung out from this small eruption.
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Ridges from fractures at the head of a 300+mile-long Martian drainage channel

Ridges from fractures 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, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “Exhumed Fracture Network,” referring to the criss-crossing ridges on the eroded mesa at the picture’s center. That mesa only rises about sixty feet from the east-west channel at the top of the picture, but the location is actually on the outside northern rim of an unnamed 70-mile-wide very eroded ancient crater. The rim itself rises another 500 feet to the south before descending 10,000 feet to the crater floor.

I am assuming by the title that the geologists believe this ridges were originally cracks that got filled with more resistant material, probably lava. The fracture network then got covered over. More recent erosion removed the material around the cracks, but the material in the cracks resisted that erosion.

The most intriguing feature in this picture however might actually be that nondescript channel.
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The mysteries buried in the Martian south pole ice cap

The mysterious layers in Mars' south pole ice cap
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Cool image time! The picture to the right, cropped and color-enhanced to post here, was taken on November 3, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture is labeled as a “terrain sample,” which means it was likely taken not as part of any specific research project, but to fill a gap in the camera schedule in order to maintain the camera’s proper temperature. In this case the camera team tries to choose interesting features, though sometimes they can’t due to timing.

In this case they were able to target a nice piece of geology, a layered 2,000 foot cliff on the outer edge of the south pole ice cap. The color strip illustrates the possibilities within those layers. I have significantly enhanced the colors to bring out the differences. The orange suggests dust, the aqua-blue water ice, though these colors could also indicate interesting mineralogies.
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Graceful beauty found within the mid-latitude glaciers of Mars

Overview map

Graceful beauty found within the glacial mid-latitudes of Mars
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 27, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The red dot on the overview map above marks the location, about 35 miles southwest of the rim of 80-mile-wide Moreau Crater. This location is also deep within the 2,000-mile-long northern mid-latitude strip I label glacier country, as almost every high resolution picture from MRO shows glacial features.

This picture is no different, in that it shows the typical lineated parallel grooves seen on the surface of glaciers both on Earth and Mars, and especially found on glaciers flowing within a narrow canyon, as this glacier is. The parallel grooves are caused by the waxing and waning of the glacier. Each layer represents a past period when ice was being deposited on the surface, with the grooves indicates times when that ice was sublimating away. The graceful curves of the grooves is due to the drift of the glacier itself downhill.

This canyon is about seven miles wide at this point, formed from the confluence of two southerly tributaries to the south. The downward grade is to the north, but the low point is not where you would expect, out into the northern lowland plains. Instead, I have marked the low point in the inset with a white dot, inside the canyon itself. It appears this glacier drains into this low spot, but then this debris-covered ice appears to vanish.

It can’t really vanish, but there is a geological mystery here that involves the alien nature of Mars. For some reason the glacier dies at this point, its material sublimating away. Is there a drainage here that sends the ice to the north by underground passages? Your guess is as good as mine.

The lineated nature of this glacial flow however is no mystery in one respect. It is quite beautiful, as seen from space.

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Mars gives us another “What the heck?” image

Another
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “layered rock.” I label it another one of my “What the heck is that?” images on Mars. If I didn’t know this was an orbital image looking down at an alien planet, I’d think it was a paisley pattern on a piece of dark fabric.

The converging “streams” suggest flows, but there really is no clear downhill grade, the landscape generally flat. The lighter patches suggest either higher terrain the flows went around, or places where something bubbled up from below. Or maybe the “flows” are actually cracks that the bubbling material filled as it rose.

I have no idea if any of these theories is right.
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A strange dune in the high southern latitudes of Mars

A strange dune in the high latitudes of Mars
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 24, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also rotated the image so that north is to the top.

The scientists label this a “dune with seasonally persistent light-toned features.” As the location is in the high southern latitudes, only about 800 miles from the south pole, light-toned features should vary by seasons, as such features usually signal the coming and going of frost, whether it be water ice or dry ice. In this case however the light tones remain from season to season, which suggests the lighter colors are intrinsic to the ground and possibly signal some interesting geology or mineralogy.

The color strip down the center of the dune is an effort to decipher this question. According to the explanation about the colors [pdf] provided by the science team, the orange and light green probably indicates fine dust, while the greenish area along the ridge’s rim as well as its eastern slope suggests frost. Thus, based on the superficial information available to the public, the colors tell us little.
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Why this place in Valles Marineris is NOT a good place to establish trails and inns

Overview map

North rim and the top of the trail
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In my cool image yesterday I highlighted a location along the north rim of the gigantic Valles Marineris canyon on Mars that appeared a great place to establish a hiking trail. The trail would take hikers down from the rim to the floor of the canyon, a distance of more than 20 miles with an elevation loss of more than 31,000 feet, more than the height of Mount Everest. The image to the right shows the top of that trail, at the rim. The white dot on the overview map above shows its location in Valles Marineris.

Because of the trail’s length I also suggested that future colonists would likely set up inns along the way, so that hikers would have places to stay as they worked their way downhill day-by-day.

There is however one major reason not to build at this particular location, and it involves the most significant geological detail I noticed in the picture to the right. Note the arrows in both this image as well as the inset above. In the picture they mark a sudden drop paralleling the rim. In the inset they also show a series of parallel cracks further north.

The cliff and the cracks suggest that the entire cliff of this part of the north rim has subsided, and is in fact beginning to separate from the plateau, and will soon (in geological terms) collapse into a spectacular avalanche. If you look at the cliff face in the inset you can see two extended outflow piles that apparently came from smaller earlier such collapses.

Could this entire cliff face, the size of Mount Everest, actually separate and crash into the canyon? If you have doubts, then take a look at the image below.
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Just one of many potential hiking trails down into Valles Marineris

Overview map

Just one of many potential trails into Valles Marineris
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 15, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The white dot on the overview map above shows the location, on the northern interior wall of the vast Valles Marineris canyon on Mars.

As my readers know, I tend to look at the spectacular Martian photos coming back from the orbiters and rovers as much from a tourist perspective as that of a scientist. Thus, for this picture, my first thought was to consider the possibility of a trail weaving its way down the nose of that ridgeline and into the canyon. In the Grand Canyon such ridgelines often provide a route down where walking is possible the entire way, with no need for climbing or ropes.

To illustrate my thought, I have indicated the potential trail with the white line. All told this trail covers about 7.2 miles, and drops 12,500 feet. Such a drop is very steep for trails on Earth, with an average grade of 14 degrees and about three times the grade considered reasonable. On Mars, however, with its one-third gravity, I think a grade this steep would be reasonable, though certainly daunting mentally. You would not only be descending on a very steep slope, you would be doing so on the peak of this ridge, with drops of one to two thousand feet on either side.

Amazingly, the inset on the overview map shows that this trail gets you less than halfway to the bottom. All told, the drop from canyon rim to floor at this location is about 31,000 feet over 20 miles, a drop that is greater than climbing down from the top of Mount Everest. If I was to install a trail here I’d also build an inn or two along the way as rest stops for hikers.

What the trail would do is get you to the bottom of this particular ridgeline. From here the trail would have to drop off into the western hollow and from then on descend on top of its alluvial fill. The slope would be as steep, but it would be possible to alleviate that by putting in switchbacks. This would lower the grade, but increase the distance traveled significantly.

Geologically, this image shows to my eye one particular feature that is quite significant, at the rim. I will discuss this tomorrow, in my next cool image.

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A Martian river of sand

Overview map

A Martian river of sand

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 26, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The red dot in the overview map above marks the location, within the western reaches of the vast Martian canyon dubbed Valles Marineris.

The picture looks at the flow of dust and sand going down the canyon’s southern rim, with particular focus on the central canyon in the picture’s center. The photo was taken as part of a long-term project, begun in 2020 to monitor this river of sand to see if any changes occur over time. Clearly the sand is flowing downhill, almost like a river, with the dunes almost resembling waves. The geological issue is to determine how fast. Based on the resolution available to me, it is impossible to tell it there have been any changes in the past four years, but the full MRO dataset might reveal more information.

To get an idea of scale, the elevation loss from the top to the bottom in this picture is about 6,000 feet. While this seems like a substantial amount, it pales when placed in the context of Valles Marineris. For example, the elevation loss for the canyon’s northern wall is about 25,400 feet, making that wall exceed in height most of the mountains in the Himalayas. And that wall extends for more than 1,500 miles.

Valles Marineris’ southern wall is more complex. It rises about 18,000 feet from the floor of the canyon to the top of the peak on which this slope sits, but then drops 6,700 feet into a parallel side canyon. From there the rise to the southern rim is about 11,000 feet. All told the southern rim sits about 23,000 feet above the canyon floor, once again a drop that would exceed most mountains on Earth.

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Land of dust devils

Land of dust devils
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Today’s cool image to the right demonstrates that the atmosphere and climate of Mars is truly different in different places. The picture, rotated, cropped, reduced, and sharpened to post here, was taken on July 22, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample”, it was likely taken not as part of any specific research project but to fill a gap in the camera’s schedule in order to maintain its proper temperature.

I post it today almost to illustrate the difference between this location and the spot where the lander Insight landed on Mars. Earlier this week the MRO camera team released a short movie created by images of the lander taken over six years, showing how the dust around it had changed over time. I noted further how those images showed a very small number of dust devil tracks, which explained why no dust devil every crossed over the lander’s solar panels to clean them of dust.

For the picture on the right, however, there are a lot of dust devil tracks, so many near the bottom that they almost completely darken the ground.
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