Tag: exploration

For original images go here and here.

Today’s two cool images above provide a nice sense of the massive nature of many Martian landslides. Scientists often call this kind of slide “mass wasting,” because rather than it occurring because a single rock propagates a larger flow of rocks as it starts rolling downhill, this slide occurs because a large section of the hillside suddenly breaks free and moves downward as a unit, carving a path as it goes.

Mars has a lot of these kinds of slides, likely caused partly by its lower gravity, 39% that of Earth’s.

The overview map to the right marks the location of both slides by their numbers. Number one took place on the eastern interior rim of a 56-mile-wide and 7,000-foot-deep unnamed crater the dry tropics of Mars. The slide dropped about 3,000 feet, beginning about halfway down from the top of the rim and not quite reaching the crater floor. The picture was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on March 31, 2024.

Number two occurred on the western interior rim of a 32-mile-wide and 6,500-foot-deep unnamed crater in the mid-latitudes where near-surface ice and glacial features are often found. In this case the slide fell downward about 3,500 feet. The picture was taken by MRO’s high resolution camera on March 14, 2024.

Despite the different latitudes and thus different climates and geological settings, both landslides look similar. It is possible they occurred under similar conditions, but at very different times. Or it is also possible that the Mars gravity and general environment promotes these mass wasting events everywhere.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 25, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this layered deposits, but that hardly describes what we are looking at. This slope, as shown in the overview map above, is the north flank of the central ridgeline inside the giant enclosed canyon depression dubbed Hebes Chasma, located just north of the main canyon of Valles Marineris, the largest known canyon in the solar system.

From floor to peak the ridge is around 16,000 feet high. Yet, its peak sits more than 6,000 feet below the plateau that surrounds Hebes. In this one picture the drop from high to low is only 5,700 feet, with thousands of feet of cliff unseen below and above.

Yet every single foot of these gigantic cliffs is layered. Based on close-up data obtained by Curiosity on the slopes of Mount Sharp in Gale Crater on the other side of the planet, the layers we can see here only represent the most coarse sedimentary boundaries. Within these layers are likely thousands upon thousands of thin additional layers, each likely representing some cyclical climate proces on Mars, even down to individual years.

Note too that the lower slopes in this picture (near the top) suggest some form of erosion flowing downhill. What caused that erosion process however remains unknown. It could have been liquid water, or glaciers, or some other process unique to Mars that we still haven’t uncovered.

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Today’s cool image is another example of how little we really understand the geology of Mars. The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on February 22, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The focus of the image is the eastern end of a large and very distinct dune field inside 31-mile-wide Matera Crater, as shown by the white rectangle in the overview map above. The field fills an area 10 by 11 miles inside the floor of the crater. On that eastern end is a very pronounced drainage gully dropping downhill about 2,000 feet to the east.

Gullies on Martian slopes, especially on the interior rims of craters, are not unusual. Though their true cause is not yet confirmed, the theories behind their existence all relate to some form of water/ice process, mostly relating to the seasonal freeze-thaw cycle.

This picture was taken in the spring, exactly when seasonal changes might be spotted. In fact, scientists have been taking regular MRO images of this gully since 2007, when it was featured image. From that 2007 caption:
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 26, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as the “relation between flutes and flows”.

The flood lava plain in the northern part of this picture represents the flows. At some point in the distant past some event, either a volcanic eruption, or a large impact, caused lava to spew out across this terrain, leaving behind a smooth plain that has only partly been marked by later crater impacts.

The many parallel ridges pointing to the northeast in the southern part of the picture represent the flutes.

One other very important flow is not directly visible. The prevailing winds that blow to the southwest are what carved these flutes, slowly pushing the material southward while carving out the many gaps between the ridges.
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Sometimes the cool geological features I find in the Mars Reconnaissance Orbiter (MRO) image archive are so large they are difficult to present on this webpage. Today is an example. The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 13, 2024 by the high resolution camera on MRO. It shows the distinct run-out of debris from a landslide that flowed downhill to the north as a single unit of material. Along the way it carved its track in the ground, almost like a ramp.

The full picture however suggested something much more spectacular. In that full image this landslide is merely a small side avalanche to a landslide many times larger. And that high resolution picture only shows what appears to be a small section of that giant slide. Obviously, this required a look at the global mosaic produced by MRO’s context camera to find out how far that avalanche actually extended.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 10, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label boringly “Lava Interactions with Landscape.”

What is the lava, and what is the landscape? Here’s is my initial guess, based simply on looking at this image alone. The mound in the middle is the landscape, the rounded top of a very ancient mountain or hill. The flat plain that surrounds it is flood lava, that in the far past poured in and mostly buried the mountain.

Everything here signals a very old terrain. To get this mountain worn so smooth from the thin Martian atmosphere has to have taken more than a billion years. And that flood lava has to also be as old, because of the number of craters on its surface. I don’t know the impact rate, but I know it takes time to accumulate this number of impacts.

The sense of age is further underlined by the moat that surrounds the hill. When that lava poured in, it would have flooded right up to the mountain slope. Over time the weakest section of lava, most prone to erosion, would be that contact point. To wear it away as we now see it must have taken many eons.

All these speculations are a very unreliable guesses. To get a better understanding of this terrain it is essential we look at more than this picture alone.
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Cool image time! The picture to the right, rotated, cropped, and enhanced to post here, was taken on December 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label “banded terrain and possible breached crater.”

Banded terrain is another name for a geological feature dubbed “taffy terrain” and only found on Mars, and furthermore only found there in Hellas Basin, the deepest giant impact basin on the red planet. This taffy terrain is considered very young, no than 3 billion years old, and formed from the flow of some form of viscous material, though what that material is remains unsolved.

This image however may help solve that mystery. The breached crater is just off frame to the upper right. The two-fingered flow coming down from the picture’s top is the flow coming out of the crater’s gap.
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