Tag: science

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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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Today’s cool image is once again another of what I dub a “what the heck?” photo. The picture to the right, cropped to post here, was taken on December 17, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and captures some very strange ridges on the plateau above Mars’ biggest canyon, Valles Marineris.

The image, labeled merely as a “terrain sample,” was taken not as part of any specific research project but scheduled by MRO’s science team in order to maintain the camera’s temperature. When they do this they try to take pictures covering something interesting, but often it is a potshot that sometimes shows little of interest.

In this case the photo shows something very strange. The ridges in the sample are packed into one area only, but if you look at the full image you will see that they are also scattered about randomly and sometimes isolated on the flat plains surrounding this spot.

Interestingly, these ridges resemble the first “What the heck?” image I ever posted in 2019. That photo was located at about the same elevation as these ridges, but due west in the volcanic plains near Mars’s giant volcanoes and just off the western edge of the overview map below.
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British biologist John Haldane once once wrote, “The universe is not only queerer than we suppose, but queerer than we can suppose.”

Today’s cool image to the right, cropped to post here, is a fine example of Haldane’s words. It was taken on January 15, 2021 by the high resolution camera on Mars Reconnaissance Orbiter of a single lone mesalike feature sticking up in a flat expanse of Mars’ south polar dry ice/water ice cap.

I emailed Shane Byrne of the Lunar and Planetary Lab University of Arizona, who had requested the photo, to ask him what he thinks we are looking at. His response:

This region has a thick layer of CO2 ice sandwiched between water ice that’s above and below. CO2 ice is denser than water ice so I think a fragment of water ice of the underlying layer has risen up through the denser CO2 ice that covers this area (what geologists call a diapir).

Byrne also admits this remains merely “just a wild theory,” not yet confirmed.

Assuming this theory to be right, in a sense then this mesa is not really a mesa at all but an iceberg of water, floating not in a saltwater liquid ocean as on Earth but on a frozen sea of dry ice. Talk about queer! The wider shot below, taken by MRO’s context camera, illustrates how isolated this water iceberg is on that dry ice sea.
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Cool image time! The pit shown in the high resolution photo to the right (image rotated, cropped, and reduced to post here) was taken on January 25, 2021 and labeled by the Mars Reconnaissance Orbiter (MRO) “Collapse Pit in Graben with Ice Fill.”

There is a lot of information in that title. First, a graben is a geological feature where a section of terrain drops relative to the surrounding terrain, producing a depression. Second, it appears the graben in this region is mostly filled with debris, probably wind-blown dust or sand or volcanic ash.

Third, at this particular spot the filling material sank, like a sinkhole on Earth, creating the pit.

And fourth, and maybe most intriguing, the scientists think that this pit is now filled with ice. At 47 degrees north latitude, the location is prime for such ice, and the interior material resembles similar glacial features seen in many other mid-latitude craters.
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