Tag: spaceflight

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 17, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows two significant features, both of which suggest the action of near-surface water ice to change to surface of Mars.

First are the gullies on the cliff wall, which also happens to be the interior slope of a 30-mile-wide crater. Since the first discovery of gullies on Mars, scientists have pondered their origin, with all their hypothesises always pointing to some form of water process. One popular theory [pdf] points to some form of intermittent water flow linked to long term climate cycles caused by the extreme shifts in the red planet’s rotational tilt, from 11 to 60 degrees. Another theory suggests the gullies form from the winter-summer freeze-thaw cycle and the accumulation of frost during winter.

The second feature are the three avalanche debris piles at the base of these gullies. The long extent of each suggests the avalanches flowed more like wet mud than falling rocks. If the ground here was impregnated with ice, than this look makes sense.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “patterned ground.” I see instead a whole range of inexplicable Martian geological features that, while each has been documented previously, each remains puzzling as to its formation process.

First there is the stucco-like peaks of all sizes on the upper left. This surface really looks like it had been wet plaster covered with Saran Wrap that had its peaks pulled up when that wrap was pulled off quickly.

Then there is brain terrain on the right. Always associated with glacier features on Mars, these convolutions are unique to Mars and as yet not entirely understood.

Next there is the circular arc on the middle left. It appears to be the remains of an impact crater now filled partly, but if so why has its northern rim disappeared so completely?

If you look close at the image above as well as the full image, you will find other mysterious features as well.

The location is the white dot on the overview map above. The rectangle in the inset shows the area covered by this picture, part of the floor of an unnamed eighteen-mile-wide and one-mile deep crater. The glacial material that appears to fill its interior as well as the splash apron that surrounds it all suggest the ground here is impregnated with water ice. Located as it is on the western end of the 2,000-mile-long north mid-latitude strip I dub glacier country — where practically every image shows glacial features — this conclusion is not surprising.

In fact, this photo illustrates well the alieness of Mars. We understand glaciers and ice, but on Mars, with its very cold temperatures, one-third Earth gravity, and thin atmosphere, those glaciers and ice are able to do things that we don’t yet understand. Untangling these geological processes will take decades of work, and likely will not be completed until people can walk the Martian surface and study it up close.

And won’t that be fun?

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label simply as a “double-rim crater.”

If you look close you might not be unreasonable to call this instead a triple-rim crater, as there appear to be two rings on each side of the highest crater rim.

Multple rings in craters are not rare. We see many on the Moon. Most however are associated with very large impacts, and are an expression of the ripples formed at impact, not unlike the ripples seen when you drop a pebble in water. Unlike water ripples, the ripples formed in rock are impact melt that quickly refreezes, thus capturing those ripples as concentric rings.

In this case, these rings likely signal not freezing rock but freezing ice.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It shows the very typical surface on a high plateau in Mars’ dry tropical regions. The dunes you see here, in this very small slice, cover a region about 80 miles square, with the prevailing winds appearing to consistently blow from the northeast to the southwest and forming these endless striations.

The dunes are made of volcanic ash, and the size of this particular ash field gives us a sense of the past volcanic activity that once dominated the red planet. Once, the atmosphere was filled with ash, which covered the ground across large regions. In the subsequent eons the thin Martian atmosphere has reshaped and piled that ash into giant mounds hundreds of miles across, with the surface striated as we see here.
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