Tag: Mars

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If you ever had any doubt about the existence of glaciers on Mars, today’s cool image should ease those doubts. The photo to the right, taken on August 27, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and rotated, cropped, and reduced to post here, shows many features that are appear identical to features found on typical massive glaciers on Earth.

Downhill is to the northwest. The many parallel grooves or fractures running along the length of the glacier resemble what are seen in many similar Earth glaciers. Some of these fractures are caused by the glaciers slow drift downward, with different sections moving at slightly different rates, thus causing a separation along the flow. Hence the parallel fractures.

These fractures also show evidence of some erosion. Because these Martian glaciers are no longer getting more snowfall, they are no longer growing. However, if the thin layer of dust and debris that protects the ice gets blown off or removed by motion, the ice is exposed and can then sublimate into gas so that the glacier erodes.

On the flow’s edges the darker parallel lines also resemble features seen on Earth, showing the exposed layers of the glacier’s past levels. The same thing can be seen on either side of the canyon’s walls.

The wide smooth section near the center of the parallel lines could very well be an impact crater that landed on this glacier sometime in the far past, and has since been distorted in shape as the glacier flowed downward.

If you still have doubts, the context image below, taken by MRO’s wide angle context camera, should help further allay those doubts.
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Cool image time! The crater on the right, the image cropped and reduced to post here, is a great example of many craters scientists have found in the mid-latitudes on Mars containing a variety of features that suggest buried glaciers. In this case we are looking at what they have dubbed a concentric crater fill, material that resembles glacial material that fills the crater’s interior and floor, and appears often to erode in a series of rings. You can see another example here.

The photo was taken on June 29, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The crater itself is located in a region of chaos terrain dubbed Nilosyrtis Mensae, located in the transition zone between the cratered southern highlands and the lowland northern plains.

Nilosyrtis Mensae is part of a region of Mars I call glacier country. When you include the mensae regions Protonilus and Deuteronilus to the west, this transition zone of random mesas, knobs, and criss-crossing canyons stretches about 2,000 miles. The context map below focuses in on Nilosyrtis Mensae, where this crater is located.
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The image to the right, cropped to post here, is a captioned photo from the high resolution camera on Mars Reconnaissance orbiter and released today. From the caption:

The black spots [recent impacts] form because the craters exposed cleaner materials in the subsurface beneath the bright, dusty surface.

Our image is also interesting because the surface has a criss-cross pattern formed by wind activity. Bright ripples that are oriented from the upper right to the lower left are perpendicular to the wind flow. In contrast, outcrops that have been eroded by the wind are oriented perpendicular to the ripples to produce the criss-cross pattern we now observe.

The overview map below might also help explain this criss-cross pattern.
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Many of the pictures from Mars show meandering channels, all of which suggest an erosion process related to some form of flow. For most of the last half century, since the first images of these channels were beamed back by Mariner 9 in 1972, scientists had believed that liquid water must have caused them. The accumulating recent photos from Mars now tentatively suggest that these channels might have instead been caused by glacial processes, creeping frozen water instead of liquid.

The image to the right, rotated, cropped, and reduced to post here, was taken on July 17, 2020 by the high resolution camera on Mars Reconnaissance Orbiter. The channels suggest some form of flow going downhill to the northwest, but was it caused by water or ice? There is no obvious visual evidence of glaciers in this image, nor is there any such evidence that I can spot in any of the nearby high resolution images of this same region, despite the fact that at 35 degrees north latitude it is in the mid-latitude band where scientists have identified many glacial features.

The region itself is called Mareotis Fossae, an area of southwest-to-northeast trending parallel fissures and ridges, as shown in the two overview maps below.
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Today’s cool image to the right, rotated and cropped to post here, shows a gully flowing down the north facing rim of a 30-mile-wide crater in the southern cratered highlands. It was taken on June 30, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

To my eye the corroded ridges and pits running down the western side of this gully look like a corroded ice, as if we are looking at a glacier that the light of the Sun, which in the southern hemisphere hits this north-facing slope more directly and for longer periods of time, is causing it to sublimate away with time.

The wider shot below shows the entire rim, flowing downhill from the south to the north.
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Whatever caused the meandering canyons on Mars, whether glaciers or liquid water, it was a process that was long-lived and multi-staged, as indicated by today’s cool image to the right, rotated, cropped, and reduced to post here. This photo, taken on June 28, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), shows a large canyon cutting downward from a high ridgeline to the north. As that canyon begins to flow out out of the mountains and into the plains to the south, a secondary inner channel appears, meandering down the center of the larger canyon.

This canyon is located at 35 degrees south latitude, in the mid-latitude region where scientists have found evidence of a lot of glaciers. In fact, there are some hints of eroded glacial material in the small channels to the west of this main canyon. Also, there appear to be patches of corroding glacial ice on the south-facing slopes of the east and west hills that define the main channel. In the canyon itself however there appear to be few if any glacial-type features.

The overview map below gives the location context.
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Today’s cool image brings us back to the region of Mars where the rover Opportunity journeyed. Taken on June 25, 2020 by the high resolution camera on Mars Reconnaissance orbiter (MRO), the photo to the right, cropped and reduced to post here, focuses on some sharp but low ridges that appear to stick up out of the Martian dust, hinting that they are the tops of some larger feature buried over the eons and only now revealed partly by recent erosion. I estimate that their height is roughly one to two hundred feet or so.

This image is in Arabia Terra, the widest and largest transitional zone region between the northern lowland plains and the southern cratered highlands. It is also only about 200 miles north of where Opportunity landed, and about 230 miles from where it died after almost fifteen years of operation, on the west rim of Endeavour Crater. The overview map below gives the context.
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 26, 2020, and shows what the scientists dub “Flow features in Reull Vallis.”

These features are typical in the mid-latitudes, and once again suggest the presence of buried glacial ice. The two lobes on the left and right both evoke such flows, as does the material in the drainage channel near the top of the photo.

What is more intriguing however are the strange features in the box. Below is that section, at full resolution.
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The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on June 24, 2020, and shows a bit of inexplicable country in Arabia Terra, the widest and largest transition zone region on Mars between the northern lowland plains and southern cratered highlands.

The stuff visible in this image falls into what I call “What the heck?” geology. It is very clear we are looking at a collection of straight and curved ridges and mesas, all of which for some reason are bright at their tips and edges. Some of the curved ridges might be the rims of craters, but only some. Other ridge lines look more like leftovers following a strange erosion process. The problem is that to my uneducated eye I can find little rhyme or reason to these shapes. The mesas and canyon on the image’s right edge might be explained by the erosion processes that create chaos terrain on Mars, but that process does not do a good job of explaining anything else in the photo.

That this uncaptioned image is merely labeled “Arabia Terra” suggests that the scientists involved in getting this image were equally perplexed by it, and could not give it a better description.

The overview map below provides some location context, including how this geology relates to the landing site of Europe’s Rosalind Franklin rover, now scheduled for a 2022 launch.
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With today’s cool image we return to what I have labeled glacier country on Mars, though this time the image shows a Martian glacial feature that while resembling vaguely such features seen on Earth, has an alienness to it that requires some explanation.

The photo to the right, cropped to post here, was taken on March 24, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The section I have focused on is the floor of a depression with a number of parallel pits, more or less aligned with the packed north-south ridges that cover the entire floor.

Normally, the north-south ridges would suggest repeated glacial flows moving to either the west or to the east. Such movement could over time, cause the ridges to separate, creating the cracks or pits that we see here. The trouble is that the slope of this depression is very unclear. In fact, the wider view below shows that this depression appears mostly enclosed, or if not it does not seem to be flowing in any particular direction.
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