Tag: Mars

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Cool image time! The photo to the right, rotated, cropped and reduced to post here, was taken on April 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a nice sample of the typical glacial-filled craters found often in the mid-latitudes between 30 to 60 degree latitudes, surrounded by a lot of erosion features representative of these lowland northern plains.

The biggest crater is very symptomatic of what scientists have dubbed concentric crater fill, a feature that they believe reveals that there is buried ice water glaciers here, protected by a thin layer of debris. The apron of brighter material surrounding the crater could be a splash feature created during impact and now more obvious because it has been revealed as sublimation and erosion lowered the terrain nearby.

The location is north of the Cydonia region in Acidalia Planitia, several thousand miles to the northeast of the region where Viking 1 landed in 1976 and Mars Pathfinder landed in 1997, as shown in the overview map below.
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Today’s cool image, to the right, takes us to the equatorial regions of Mars, a region that today appears quite arid and dry based on all the orbital and rover/lander data so far gathered. The photo and its complex geology however provides us a hint that once liquid water did exist here. At least, that is the hypothesis that scientists presently favor, though making it fit this complex geology is not simple or straightforward.

The mosaic to the right is made from four context camera images taken by Mars Reconnaissance Orbiter (MRO). It shows a very complicated series of depressions — one of which vaguely resembles a crater — that appear to have been washed out by some past erosion process, though that process could not have been that simple because of the fissures and cracks that dominate the floor of the circular feature.

I contacted Chris Okubo of the U.S. Geological Survey, who had requested a high resolution image from MRO of a small part of this mosaic, as indicated by the white box, to ask him what we are looking at. His answer was appropriately noncommittal:
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on April 19, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Requested by Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Arizona, the image was entitled “Enigmatic Terrain in Elysium Planitia.” The image is labeled so because, as Dundas explained,

Flood lava is a key part of the feature, best seen at the north and south ends of the image. What’s unusual is the knobby terrain at the center. … I haven’t yet been able to do a more thorough study of these features, so plenty of puzzles remain!

The higher material in the upper right is likely flood lava. A 2016 paper [pdf] led by Dundas on similar features in Elysium Planitia that were not as knobby found their origin somewhat baffling. The evidence suggested that lava, mud, wind, and ice could all be involved in their formation, but the evidence was also not sufficient to eliminate any possibility.

In the case of today’s image, the explanation might also be any of these possibilities. For example, we might be looking at the erosion of the flood lava, exposing harder knobs of different material that had been there before and had been covered by the lava. Or maybe the knobs are simply the last bits of that layer of flood lava that has not yet eroded away.

As always, the overview map provides some context.
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