Tag: Mars Reconnaissance Orbiter

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Cool image time from Mars! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It highlights a string of craters, all lined up in an almost straight line.

Were these craters caused by the impact of an asteroid that broke up as it burned its way through the thin Martian atmosphere? The lack of any raised rims argues instead that these are sinks produced not from impact but from a collapse into a void below, possibly a fault line.

Yet, almost all of the craters in this image, even those not part of this crater string, show no raised rims. If sinks, the voids below don’t seem to follow any pattern, which once again argues in favor of random impacts, with the string produced by a bolide breaking up just prior to hitting the ground.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists dub as “large gullies with infilled alcoves.”

Gullies on Mars were one of the first discoveries by orbiters of small-scalle potential water-caused features on the Red Planet. The favorite explanation for their formation today involves the seasonal freeze-thaw cycle, combined with the deposition of ice and dry ice frost in the winter. When that ice and dry ice sublimates away in the spring it causes collapse and erosion, widening the gullies.

These gullies also exhibit evidence that underground and glacial ice might contribute as well. The material in the largest gullies looks like a mixture of glacial material and dust and debris. It could also be that there is ice impregnated in the ground, which can cause large collapses when it sublimates away.

The white rectangle on the overview map and inset above marks the location of this picture, on the western rim of a 13-mile-wide unnamed crater inside the western portion of the 2,000-mile-long mid-latitude strip on Mars I dub glacier country, since every image from orbit shows evidence of glaciers.

This picture is no different, as the horizontal cracks at the base of the crater rim suggests the glacier that fills the crater floor is being pulled apart by gravity at its edges. The elevation drop from the top of the rim to the floor is about 3,200 feet, so any ice on that slope will definitely be stressed by gravity. Such cracks are therefore not surprising.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the northeast corner of an unnamed 7-mile-wide crater, located near the equator in the dry Martian tropics.

The MRO science team labels this “crater and lava fill”, suggesting that the crater interior is filled with lava material. The nature of that crater floor reinforces this conclusion, as it is relatively smooth and does not have rough aspects of glacial material found in craters in the mid-latitudes. Instead, it looks like a frozen lake of lava that has the peaks of mostly buried features poking up at various spots.

What makes this crater interesting however are the gullies on the northern interior rim. Gullies on Mars are normally thought to be associated with some water-frost-ice process, probably seasonal, where the thaw-freeze cycle causes small collapses and avalanches. Yet, this crater is almost at the equator, in a very dry region where no evidence of near-surface ice is found. Gullies here suggest the hypothesis for explaining the gullies on Mars have not quite solved the mystery.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small section of the floor and northern slope of Hebes Chasma, one of the many very large enclosed pits that can be found to the north of Valles Marineris, the largest canyon in the solar system. Though Hebes seems small next to the 1,500 mile long Valles Marineris, it still is 200 miles long by 80 miles wide, and could easily fit a half dozen Grand Canyons within it.

For example, the Grand Canyon is from 4,420 to 5,400 feet deep, hiking down from the south and north rim lodges respectively, which sit about ten miles apart. On this picture, the peak on the right sits about 5,300 feet above and only about 3.8 miles from the low spot on the bottom left, which means this one small picture encapsulates the Grand Canyon. And yet, the northern rim of Hebes sits another 21,000 feet higher and twelve miles away. And the entire chasma itself extends 50 miles to the west, 150 miles to the east, and 50 miles to the south.
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Today’s cool image will be a mystery with the answer below the fold. Before you look at the answer, however, you must try to come up with your own explanation for the picture to the right, cropped to post here, that was taken on September 25, 2018 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

What we see in this picture is what looks like a striped terrain, alternating bands of light and dark. What caused the bands? Why the different colors?

The overview map above provides some clues. The white rectangle inside Juventae Chasma near the map’s center marks the area within which this picture was taken, though the picture to the right covers only about a pixel inside that rectangle.

Can you guess what these stripes reveal, from this little information? For this quiz to work you must make a guess, but be prepared to be wrong and quickly reassess your conclusions. Such is the real scientific method, so rarely taught now in schools.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The features are described as “ribbed terrain” in the label. To my eye they more resemble flakes of peeling paint, most especially the mesas in the lower left. On the full image there are many more examples that resemble old paint peels, barely attached to the wall.

The white dot on the overview map above marks the location, deep inside the 2,000-mile-long strip in the northern mid-latitudes I dub glacier country, because everything seems covered by glacial features. This location is at 42 degrees north latitude, where plenty of near-surface ice features are found on Mars.

At first glance it looks like the top “paint-peel” layers to the south have been slowly sublimating away, leaving behind the smooth plain to the north. The problem is that this smooth area in the full image actually appears to be a glacial ice sheet of its own, filling all the low areas between mesas.

In other words, we are probably looking at layers and layers of ice sheets, each created during a different Martian climate cycle, caused by the wide swings of the planet’s rotational tilt, or obliquity.

The location is within Arabia Terra, the largest transitional zone on Mars between the northern lowland plains and the southern cratered highlands. Thus it sits above the glaciers that fill the lower regions of chaos to the north. What we have here is terrain that will eventually become chaos terrain, as the narrow faults and cracks are slowly widened into canyons by the cycles of glacial activity.

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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 28, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture label describes it as a “Low Shield Vent and Pit Northeast of Arsia Mons,” suggesting these depressions are volcanic in nature. We know the pit in the lower left is not an impact crater because it has no raised rim of ejecta. Instead, it looks like a collapsed sinkhole, formed when the ceiling above a void could no longer support its weight. Similar, the trench to the northeast is aligned with the downhill grade to the northeast, with its features suggesting a vent draining in that direction.

The ample dust inside the trench and pit suggest that it has been a very long time since this vent was active. Research suggests volcanic activity last occurred in this region from 10 to 300 million years ago, so that gives us a rough estimate of this vent’s age. Since then any dust that is blown into it will tend to become trapped there.
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