Tag: geology

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Cool image time! The photo to the right, cropped and reduced to post here and taken on January 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), provides us a perfect example of the kind of glacial feature that scientists find routinely in the 30 to 60 degree mid-latitude bands on Mars. In this case the crater is in the northern reaches of a chaos region dubbed Nilosyrtis Mensae, the easternmost mensae region of what I dub glacier country on Mars.

When first identified scientists named this concentric crater fill, a purposely vague term that is only descriptive because they then did not know what it was made of, though they had their suspicions that it was buried glacial ice. Since then radar data has routinely confirmed that there is ice in such filled craters, making this particular glacial feature one of the most prevalent in those mid-latitude bands.

You can see a quite similar ice-filled crater, also in Nilosyrtis, in an earlier post from October 2020. While that earlier crater was on the southern edge of Nilosyrtis, today’s crater is about 300 miles almost due north, near the region’s northern fringe. In between are lots of similar glacial features, sometimes in craters, sometimes flowing off the slopes of mesas, and sometimes flow features in the open canyons between.

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Cool image time! The photo to the right, rotated cropped, and reduced to post here, is only a small example of the strangely tilted and twisted strata in the central peak region of 38-mile-wide Martin Crater on Mars. The full image shows more.

The picture was taken on January 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The section I’ve cropped out shows a series of stratified strata that are are not only significantly tipped from the horizontal, but have also been bent and deformed.

The crater itself is located about 260 miles south of Valles Marineris, as shown on the overview map below.
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Cool image time! The Cydonia region on Mars, located at around 30-40 degrees north latitude in the northern lowland plains just beyond the transition zone up to the southern cratered highlands, is well known to many on Earth because it was here that the Viking-1 orbiter took a picture of a mesa that, because of the sun angle, made its shadows resemble a face. Thus was born the “Face on Mars” that consumed the shallow-minded among us — and thus the culture, media, and Hollywood — absurdly for decades, until Mars Global Surveyor took the first high resolution image and proved without doubt what was really obvious from the beginning, that it was nothing more than a mesa.

Cydonia however remains a very intriguing region of Mars, mostly because it is home to a lot of strange geology, as shown by the photo to the right, rotated, cropped, and reduced to post here. Taken on January 16, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows some of that strange and inexplicable geology.

While Cydonia is inside that 30-60 degree latitude band where MRO has imaged numerous glacial-type features, I do not know if many such features have been found there. Except for the pits and depressions in the photo’s lower right — which suggest decay in an ice sheet — little else at first glance in the picture clearly invokes any of the obvious glacial features one comes to expect. There appear to be what might be lobate flows in the image’s center going from the west to the east, but if they are glacial, they are so decayed to as leave much doubt.

The overview image below shows where Cydonia is on Mars, and helps explain partly what is found here.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a particularly ugly region of rough terrain located about 900 miles to the southwest of the giant volcano Arsia Mons, the southernmost of the chain of three giant volcanoes between Olympus Mons and Valles Marineris. The picture sits inside the floor of a very old and degraded 185-mile-wide crater dubbed Koval’sky.

The section I cropped out was picked at random, because the entire full image looked like this. Though only a handful of images have been taken of the floor of Koval’sky Crater by MRO’s high resolution camera, all show similar rough terrain. In June 2017 the MRO science team posted one of those few such photos with the following caption:
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Today’s cool image from Mars highlights what is probably the biggest geological conundrum the red planet presents for planetary scientists. The photo to the right, rotated, cropped, and reduced to post here, was taken on February 1, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Though I have cropped it, I have cropped out very little, because the entire meandering drainage valley is its most interesting feature, and that takes up almost the entire image.

The photo was simply labeled by the camera team a “terrain sample northwest of Sytinskaya Crater”, so I suspect this was taken not in connection with any specific research but because they must use the camera at a regular intervals to maintain its temperature, and when they have gaps in their schedule they try to pick spots of interest in areas that have not had many high resolution photos taken. In this case however I suspect the location choice was very far from random, as they clearly wanted to capture this drainage system, in its entirety.

I called this merely a drainage channel without indicating what caused the channel, be it liquid water, ice, or wind, because in this case that is a main question. At first glance an Earthman will immediately suspect water, which is what scientists supposed for the last half century. The problem with that conclusion is that the Martian atmosphere is too cold and thin for liquid water to exist on its surface, and though there seems to be plenty of evidence that liquid water once existed there, no scientist has yet come up with a completely accepted climate model that allows for such conditions in anytime in Mars’ past.

The rover Opportunity found that some channels it explored might have been carved by wind, though to our human eyes it seems unlikely that a meandering tributary system such as this could have been carved by wind. The possibility however must not be dismissed out of hand, since Mars is an alien planet and alien things (to Earth) happen there.

The overview map below might provide some context.
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Today’s cool image on the right, rotated, cropped, and reduced to post here, is part of a series of cool images that have repeatedly shown the blobby and squishy look of crater impact sites in the Martian northern lowland plain dubbed Utopia Planitia. Taken on January 2, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), it shows the southeast rim of a very distorted crater that appears filled with glacial material and is also surrounded by an apron of smooth material.

At 42 degrees north latitude, it is somewhat expected to find evidence of glacial-like features in such a crater. Moreover, throughout the 30 to 60 degree mid-latitude band in Utopia Planitia are found numerous such blobby craters (other examples found here, here, and here), all suggesting that the impact occurred on a flat plain with a layer of water ice close to the surface. The heat of the impact melted that ice layer. In such a circumstance, the crater rims were easily deformed because as liquid water (for a short time) it could flow into any number of shapes.

At least that’s my theory. According to Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Arizona,

The exact processes that create the patterns are still debated. The flattened/degraded rims are not necessarily related to this morphology, as such craters can have sharp rims, so they may relate to post-impact modification.

In other words, later erosion after the crater formed could have rounded the rim and maybe even distorted it from a circle.

Regardless, the processes that made this crater rim look as it does were clearly widespread, as shown in the wider view below, provided by the context camera on MRO.
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