Tag: Mars Reconnaissance Orbiter

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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on February 17, 2012 by the wide-view context camera on Mars Reconnaissance Orbiter (MRO). It shows a section of the northern lowland plains of Mars, latitude 31 degrees north, where several very inexplicable and isolated ridges can be seen.

One ridge meanders mostly in a north-south direction, while a second instead meanders east-west. The shape of both says that neither has anything to do with any past impact crater. In fact, their random snakelike shape doesn’t really fit any obvious explanation. For example, they do not fit the look of the many fossil rivers found on Mars, where the hardened and dry riverbed channel resists erosion and becomes a ridge when the surrounding terrain erodes away.

What geological process caused them? In the decade since this photo was taken the scientists who use MRO have only been able to snap a handful of high resolution images of these ridges. The image below is the most recent, covering the area in the white rectangle above.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Simply labeled “slope features,” it was likely taken to monitor the gullies and streaks on the interior walls of this 4-mile-wide crater. Scientists have been using MRO to track the coming and going of frost on this crater’s interior walls since 2016.

Equally intriguing however are what appear to be squashed layers within the crater’s interior. These appear to be some form of glacial feature created by repeated climate cycles, similar to the glacial features routinely seen throughout the 30 to 60 degree mid-latitude strips north and south.

What makes the glacial features in this particular crater particularly intriguing is its location, as shown in the overview map below.
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Cool image time! The photo above, rotated, cropped, and reduced to post here, was taken on March 5, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “viscous flow feature,” which is another way of saying the flow was thick and syrupy.

Nor is such a flow unusual in this area of Mars. It is located in a region of chaos terrain dubbed Protonilus Mensae, which is also the central mensae region in the 2,000-mile-long strip in the northern mid-latitudes of Mars I label glacier country. The overview map above of Protonilus Mensae — covering about 500 miles in width — shows how common such flows are in this place. The black rectangles mark the locations of other cool images I have featured, as follows:

• 1. Buried glaciers flowing off of Martian mesa
• 2. Brain Terrain on Mars
• 3. How to spot a glacier on Mars
• 4. Glacier country on Mars
• 5. Revisiting Mars’ glacier country
• 6. Back to Mars’ glacier country
• 7. A cracking Martian glacier?
• 8. Ice-filled craters in Mars’ glacier country?

The red rectangle indicates the location of today’s cool image.

The glacial aspect of everything in this region is even more emphasized by the wider view provided by MRO’s context camera below.
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on November 22, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labeled a sinuous ridge. Make sure you also look at the full image. The ridge goes on to the south, but then fades way as an almost perfect ramp, only to have another even more wiggly but thinner north-south ridge begin only a few feet to the west.

Sinuous ridges like this are found in many places on Mars. Almost always their origin is thought the result of a former river channel that became a ridge when the surrounding softer material eroded away.

That explanation however does not seem to work for this ridge. It has too many other inexplicable features. For example, note how the peak of the ridge smoothly transitions from sharp to flat-topped. It has a soft appearance that is strengthened by the gap near the top.

It is almost as if this ridge is a kind of elongated sand dune! And guess what: The overview map below gives that explanation some believability.
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In our third Martian cool image of the day, we go to the north pole of Mars, as seen from orbit by the high resolution camera of Mars Reconnaissance Orbiter (MRO). Taken on March 30, 2022 and cropped and reduced to post here, this picture shows some of the distinct and unique geological features found only on the polar caps of Mars. From the caption by Candy Hansen of the Planetary Science Institute in Tucson, Arizona:

Both water and dry ice have a major role in sculpting Mars’ surface at high latitudes. Water ice frozen in the soil splits the ground into polygons. Erosion of the channels forming the boundaries of the polygons by dry ice sublimating in the spring adds plenty of twists and turns to them.

Spring activity is visible as the layer of translucent dry ice coating the surface develops vents that allow gas to escape. The gas carries along fine particles of material from the surface further eroding the channels. The particles drop to the surface in dark fan-shaped deposits. Sometimes the dark particles sink into the dry ice, leaving bright marks where the fans were originally deposited. Often the vent closes, then opens again, so we see two or more fans originating from the same spot but oriented in different directions as the wind changes.

The top layer of translucent dry ice falls as dry ice snow during the winter, than sublimates away with the arrival of spring. Since this photo was taken in autumn, we are looking at features left over from the activity from the spring and summer.

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Cool image time! The photo to the right, cropped to post here, was taken on February 27, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a nice collection of what scientists have informally (but permanently) labeled as spiders, strange formations that exists only in the regions of the Martian south pole.

The spiders are believed to have formed because of the coming and going of the dry ice mantle in the polar regions that falls as snow in the winter and then sublimates away come the spring. Because dry ice is mostly clear, the spring sunlight penetrates it and warms the underlying surface, which acts to warm the base of the dry ice mantle. CO2 gas builds up, trapped below the dry ice, until the pressure causes it to break the dry ice at a weak point and spew outward, carrying with it dust that blackens the surface above. You can see three examples in today’s image.

Spiders however only happen at the south pole. In the north much of the terrain is formed by unstable dunes, which change from year to year, thus causing the gas breakage to occur at random and different spots.

In the south however the terrain is more stable, a surface of ice and dirt. The spiders form because the trapped gas always follows the same path from year to year to the same weak points, carving riverlike tributaries until these feeders combine and build up enough gas pressure to crack the overlying dry ice so that the gas can escape.

Though the gas functions much like a river of water, it has one fundamental difference that makes this phenomenon wholly Martian and quite alien. On Earth rivers flow downhill. On Mars, the gas in these spider tributaries is flowing upward, seeking a path into the atmosphere above.

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Cool image time and a mystery! The photo to the right, cropped to post here, was taken on March 29, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) of an 18-mile-wide crater in the southern cratered highlands of Mars. The full picture, dubbed “Steep Cliff,” was taken apparently to get a good view of the crater’s northern rim. The rim’s steepness suggests that the floor of the crater is significantly filled.

More intriguing however are the scattering of strange depressions about six miles south of the rim. What caused them? The crater’s location is in a part of Mars where it is not unusual to find both glacial features as well as flood plain lava. In fact, the crater’s northeast and southwest rims appear to have been buried by what appears to be flood lava. The northern rim’s shallowness also suggests the crater is well filled with flood lava.

However, the crater is also at 38 degrees south latitude, a latitude where planetary scientists have found lots of glacial features. Much of this crater fill could be glacial.

The overview map below illustrates this mystery.
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Cool image time! The picture to the right, rotated, cropped, reduced, and annotated to post here, was taken on September 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows what appear to be a variety of flows, from alluvial fill to slope streaks to dust coming down the southeastern interior rim of 77-mile-wide Orson Welles Crater on Mars.

The location is almost right on the equator, so none of these flows are ice- or water-related. Nor are such flows unusual in the meandering 800-mile-long canyon that cuts through Orson Wells crater, dubbed Shalbatana Vallis. I featured similar flows at a spot to the north and downstream from this one in May 2021, also on the canyon’s eastern rim.

The overview map below provides some context.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a cliff escarpment that, based on a rough estimate of MRO’s elevation data, ranges from 10,000 to 13,000 feet high. Because the sun is only about 32 degrees above the western horizon, the shadows are long and distinct and bring out the features quite dramatically.

On Earth, a mountain 13,000 feet high would generally be named, because there are really not that many of them. If it was a cliff face dropping down into a canyon, which this Martian cliff is, it would be quite unique and probably be one of the most popular tourist spots on the globe. For comparison, the rim of the Grand Canyon in the national park, visited by millions, is only 4,000 to 6000 feet in elevation. This cliff on Mars is more than twice as deep, and yet, it is hardly the most spectacular canyon rim on the red planet.

The overview map below explains this.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 10, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It shows what planetary scientists have dubbed “brain terrain”, a truly unique Martian geological feature that is not found on Earth and also remains as yet unexplained. Specifically, the brain terrain is the speckled areas between the larger flow features, all of which are probably ice or glacier related.

What especially drew me to this MRO image however was the particular flow feature in the center left that looks like either a giant squid or something out of Lovecraft horror short story. Talk about a cool image!

The downward grade here is likely to the north, as this spot is inside a north-south canyon, cutting into the southern cratered highlands. The general north-south trend of the depression here reinforce this supposition.

The overview image below provides context.
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Yesterday’s Picture of the Day from the high resolution camera on Mars Reconnaissance Orbiter (MRO) revisited a captioned image first posted in February 2014 by the science team. That picture, cropped and enhanced, is to the right. From the 2014 caption:

There is a large channel system that flows into the basin, called Ladon Valles, and scientists think that the basin may have once filled with water before another channel to the north formed and drained it. These exposures of light-toned layered sediments provide clues about the environment that existed within Ladon Basin when water may have ponded and deposited these sediments.

Later research has generally concluded that these white sediments are iron and magnesium smectites, often appearing as white tuff material whose deposition is generally associated with precipitation of water or snow and its subsequent evaporation or sublimation.
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on January 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be at first glance a relatively featureless plain with a lighter material covered by a patchwork of darker material.

Note however the lack of craters. Except for several faint depressions near the image’s center, there are none. And those depressions look like the expression of craters that have been covered by material. Is the two-toned surface here an expression of past lava flows? Or are we seeing an ice-sheeted plain, with the patches representing higher terrain above that plain?

The overview map below answers the question somewhat clearly.
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