Tag: Mars Reconnaissance Orbiter

A Martian river canyon?

11:56 am

A Martian river canyon?
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Today’s cool image highlights the biggest mystery of Mars that has baffled scientists since the first good pictures of its surface were taken in the early 1970s by the Mariner 9 orbiter. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a very small segment of the 400-mile-long meandering canyon on Mars called Nigal Vallis. From the Wikipedia page:

The western half of Nirgal Vallis is a branched system, but the eastern half is a tightly sinuous, deeply entrenched valley. Nirgal Vallis ends at Uzboi Vallis. Tributaries are very short and end in steep-walled valley heads, often called “amphitheater-headed valleys.”

We can see one of those short tributaries on the image’s left edge. The overview maps below provide a wider view of this entire canyon.
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Searching for surface changes caused by the biggest recorded Martian quake

1:27 pm

Location of May quake
The white patches mark the locations on Mars of the largest quakes detected by InSight

On May 4, 2022, the seismometer on the InSight Mars lander detected a 4.7 magnitude earthquake on Mars, the largest ever detected.

The map to the right shows the approximate location of that quake by the white patch with the green dot. (You can read the paper describing this quake here [pdf].) This is also the same approximate location of a small five-mile-wide crater known to have many slope streaks on its interior walls.

Slope streaks are a uniquely Martian geological feature whose origin remains unknown. They resemble dark avalanche streaks flowing downhill, but make no changes in the topography, and lighten with time. They also occur randomly throughout the year. Two slightly different theories for their formation suggest that the streaks are triggered by the fall of dust particles, though neither is proven or even favored.

If either of these theories are true, then the 4.7 magnitude earthquake at this location should have caused the formation of more streaks. To find out, scientists have used the high resolution camera on Mars Reconnaissance Orbiter (MRO) to compare that crater both before and after the quake to see if any new streaks has appeared. Below is a side-by-side comparison of these images.
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A collapse on Mars

1:34 pm

A collapse on Mars
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The photo to the right, cropped, reduced, and enhanced to post here, was taken on October 27, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The full photo was simply labeled as a “collapse feature”, and because it contained a few other sinks to the north beyond the top edge of this cropped picture, it is unclear if the scientists were referring to this sink in particular.

This sink is the most interesting however, because it really looks like something had sucked material out from below, causing the surface crust to fall downward, intact except for some cracks along the perimeter of the collapse.

The overview map below as always provides some context that might explain what we are seeing.
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Defrosting Martian Dunes

3:07 pm

Defrosting Martian dunes
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Cool image time! The photo to the right, cropped, reduced, and sharpened to post here, was a captioned image on January 6, 2023 from the science team of the high resolution camera on Mars Reconnaissance Orbiter (MRO). From the caption by Alfred McEwen of the Lunar & Planetary Laboratory in Arizona:

In the late winter when first illuminated, the carbon dioxide frost at high latitudes will begin to sublimate. Over sand dunes, the defrosting spots and mass wasting on steep slopes produce striking patterns. This scene is especially artistic given the shapes of the dunes as well as the defrosting patterns.

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The dry and dusty equatorial regions of Mars

1:50 pm

The dry cratered highlands of Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on October 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a cluster of craters filled with ripple dunes.

The color strip tells us something [pdf] about the surface materials here. The reddish-orange in the craters is thought to be dust. The greenish terrain above the craters is likely coarse rock or bedrock, covered with a veneer of dust.

There is no ice here, just dust that over time has become trapped in the craters and cannot escape. And though there is also dust on the surrounding terrain, there is not that much. The craters themselves are likely very ancient, based on their shape and the eroded condition of their rims.

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Drainage out of a Martian crater

12:42 pm

Drainage out of a Martian crater
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Today’s cool image to the right, rotated, cropped, reduced, and sharpened to post here, not only gives us another example of a Martian geological feature that is unique to Mars and whose origins are not yet understood, it also shows what appears to have once been a lake-filled crater that over time drained out to the east through a gap.

This picture was taken on October 14, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The inexplicable geology is called brain terrain, and it fills the floor of the crater on the picture’s left side. The rim shows a gap, from which a meandering channel continues downhill to the east. The lake inside the crater might not have been liquid water, but ice. The channel might not have been formed by flowing water, but by a glacial flow downhill.

What makes this glacial evidence especially interesting is that it is located in a very different part of the Martian mid-latitudes.
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The soft icy Martian northern lowland plains

11:15 am

The soft icy Martian northern lowland plains
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In a cool image post last week, I noted that the near surface “ice sheets in the northern lowland plains are never … smooth, even if well protected.” The picture to the right, cropped, reduced, and sharpened to post here, provides an excellent example. It was taken on November 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

It is winter, and the sunlight is coming from the southwest, only 27 degrees above the horizon. The mound on the left is soft, while the depression on the upper right appears to have sand dune ripples sitting on top of a flat glacial mound. This depression may be an eroded crater (no upraised rim) or it could be a sink caused by the sublimation of the near surface ice.

Everywhere else the flat plains are stippled with small knobs.

The overview map below provides more context.
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A spray of Martian hollows

11:42 am

A spray of Martian sinks
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Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 12. 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Dubbed simply as a a “terrain sample” by the science team, the picture was not taken as part of any specific research project, but instead to fill a gap in the orbiter’s shooting schedule so as to maintain the camera’s proper temperature. When MRO’s science team does this, they try to pick something in the area below that might be interesting. Sometimes they succeed, but often the features in the picture are nondescript.

The white line delineates the rim of a faint and very eroded small crater. Are the depressions that are mostly concentrated just to its south and east sinks or past impact craters? I haven’t the faintest idea. The overview map below helps to answer this question, but only partly.
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A hint at Mars’ past climate cycles

11:16 am

Terraced glaciers in Martian crater
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Cool image time! The photo to the right, cropped to post here, was taken on October 28, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “layered feature” inside a small 4,500-foot-wide crater.

Located at 36 degrees north latitude, we are likely looking at glacial ice layers inside this crater, with each layer probably marking a different Martian climate cycle. The terraces suggest that during each growth cycle the glaciers grew less, meaning that less snow fell with each subsequent cycle. This in turn suggests a total loss of global water over time on Mars.

The overview map below gives us the wider context.
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A “What the heck?” glacier image on Mars

5:36 pm

Glacial material on Mars
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Sometimes a cool image goes from bafflement to obvious as you zoom into it. The cool image to the right, cropped to post here, does the opposite. It was taken on October 11, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have purposely cropped it at full resolution, so that its eroded glacier nature is most obvious.

The cracks and hollows are likely caused by the sublimation of the near surface underground ice, breaking upward so that the protective surface layer of debris and dust collapses at some points, and cracks at others.

The overview map below further confirms the likelihood that we are looking at glacial features, but when we also zoom out from this close-up we discover things are not so easily explained.
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Finding Martian glaciers from orbit

11:45 am

Glacier flow on Mars
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Today’s cool image is a great example of the surprises one can find by exploring the archive of the high resolution pictures that Mars Reconnaissance Orbiter (MRO) has produced since it arrived in Mars orbit back in 2006. The picture to the right, rotated, cropped, and reduced to post here, was taken by MRO’s high resolution camera back on May 4, 2017. I only found it because I had picked out a October 24, 2022 high resolution image that covered a different area of this same flow feature just to the north east. In trying to understand that 2022 picture I dug to see other images had been taken around it, and found the earlier 2017 photo that was even more interesting.

Neither however really covered the entire feature, making it difficult to understand its full nature. I therefore searched the archive of MRO’s context camera, which has imaged the entire planet with less resolution but covering a much wider area per picture. The context camera picture below captures the full nature of this feature.
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Cones, mounds, and layers of Martian ice?

2:20 pm

Cones, mounds, and layers of Martian ice?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on September 10, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The location is at 38 degrees north latitude, in the Martian northern lowland plains. At this latitude in these plains the geological features seen in high resolution pictures almost always invoke near surface ice, including processes that disturb that underground ice layer.

This picture is no different. Not only does it appear that a glacier is flowing down from the top of east-west ridge, the middle mound includes a crater with its southeast rim gone and appears filled with material that suggests ice.

The greater geographic context of this location can be seen in the overview map below.
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Bursting lava bubbles on Mars

10:58 am

Burst lava bubbles on Mars
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Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 4, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

I really have no idea what caused these distorted cones. My intuition (a dangerous thing to rely on when it comes to science) suggests these are volcanic in nature. Imagine hot lava with gas bubbling up from below. Periodically a gas bubble will burst on the surface releasing the gas. Depending on temperature, that bursting bubble could harden in place.

The overview map below provides some support for my intuition, but it also suggests this first hypothesis could be completely wrong, something that does not surprise me in the least.
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A congregation of Martian dust devils

12:13 pm

A congregation of Martian dust devils
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Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 9, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a spot on Mars where, as indicated by the many many tracks, dust devils routinely develop and travel across the surface.

Though this whole region appears to favor dust devils, within it are places that are even more favored. For example, the number of tracks on the northern and eastern slopes of that small hill at center left practically cover the surface, while the hill’s western and southern slopes are almost untouched.

Both the overview map and the global Mars map below provide the full context.
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Big sink near the Martian south pole

12:38 pm

Big sink near the Martian south pole
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Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 12, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The image is rotated so that south is at the top. The science team labels this a “subsidence feature,” or in plain English, a sinkhole.

Its perfectly circular shape, plus its central peak, strongly suggests we are looking at an impact crater. However, the lack of a raised rim of debris, produced by the ejecta from the impact, raises questions about this conclusion, and is one reason why the scientists think this is a sinkhole instead. Its shape however could be telling us that this sink is simply mirroring the existence of a buried crater.

The overview map below as always provides more context.
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The edge of the Martian south pole ice cap

2:42 pm

The edge of the Martian south pole ice cap
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Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 4, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The MRO science team labeled this simply “Diverse Terrain,” an apt description but woefully incomplete.

Though the grade here goes uphill to the south, there are ups and downs along the way. The flat areas near the top as well that band near the bottom appear to be the oldest terrain, with the rough hollows appearing to be places where that flat material has sublimated or eroded away.

This terrain is in the very high southern latitudes. South is to the bottom of this picture, with the south pole of Mars about 380 miles away. Thus, that eroding top layer is likely disappearing because it has either water ice or dry ice within it, and over time it sublimates away.

The picture itself was taken in winter, when the entire surface is likely covered with a thin mantle of dry ice that fell as snow with the coming of colder temperatures. A wider view of this region in the spring, taken by MRO’s context camera, shows that this mantle, now appearing like white frost, appears largely confined to the higher terrain. Apparently, the annual sublimation of this dry ice mantle is linked somehow to the erosion of this flat terrain.

The additional location information provided by overview map below helps explain why this terrain is so diverse.
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Sunken butte on Mars

1:03 pm

Collapsed butte in the Martian northern lowland plains
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Cool image time! The photo to the right, cropped, reduced, and sharpened to post here, was taken on November 1, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label a “layered butte.” Like the mesas in the American southwest, those layers, or terraces, mark the geological history of this place, where over time layer upon layer was placed down, and then eroded away except for this mesa.

What makes the mesa even more intriguing and strange, however, are surrounding concentric cracks and the moat at the mesa’s base. These features suggest that at some point the ground below the mesa collapsed so that the entire mesa dropped, as a unit.

What could cause this? The overview map below provides a clue, though certainly not an answer.
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The featureless volcanic ash plains of Mars

2:04 pm

The featureless volcanic ash plains of Mars

Cool image time! The photo to the right, cropped, reduced, and sharpened to post here, was taken on September 10, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be a relatively featureless plain with a surface resembling stucco.

At -9 degrees south latitude, this is in the Martian dry equatorial regions. No ice or glaciers here. However, the consistent orientation of the knobs and hills suggest dunes and sand blown by prevailing winds, and that guess holds some truth. This location is deep within the Medusae Fossae Formation, the largest volcanic ash deposit on Mars, covering an area about as big as India, and believed to be the source of most of the red planet’s dust.

We are thus looking at thick layer of ash, its surface shaped over eons by the winds of Mars’ thin atmosphere.
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Strange terrain on the eastern floor of Gale Crater

1:10 pm

Strange terrain on the eastern floor of Gale Crater
Click for full image. For the inset, go here.

Though today’s cool image on the right, rotated, cropped, and reduced to post here, shows a small section on the floor of 96-mile-wide Gale Crater where Curiosity has been roving for the past decade, this picture looks at a different place. Curiosity landed in the northwest quadrant of the crater, and has been climbing the western slopes of Mount Sharp, which fills much of the crater’s interior. Today’s image looks at the crater’s floor on the east side of Mount Sharp.

The picture was taken on September 30, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The dark areas are likely dune seas, while the golden section near the top of the color strip is likely dust, though that is not certain. (This bright yellow is unusual for this particular color filter.) The greenish color suggests coarser materials, such as larger boulders and rocks, though this is also not certain.

The inset zooms into some unusual polygon lines that cut across the dunes and cratered terrain. Such lines suggest that once, in the far past, the ground here was wet. When it dried out (being now in the very dry equatorial regions of Mars) it formed these cracks, similar in nature to the polygon cracks one sees in drying mud on Earth. Since the data from Curiosity when it was on the crater floor also suggests a lake once existed inside the crater, these cracks add weight to that conclusion.

The overview map below places Gale Crater in the larger context of Mars.
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Ancient lava flows down the flanks of the solar system’s largest volcano

11:52 am

Lava flows on Olympus Mons
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Cool image time! The photo to the right, cropped, reduced, and sharpened to post here, was taken on October 2, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be very old and eroded lava on the northeast flanks of Olympus Mons, the largest volcano on Mars as well as the entire solar system. About 600 miles across, from the edge to its peak, Olympus rises about 54,000 feet, with an actual height relative to Mars’ “sea level” of just under 70,000 feet, more than twice as high as Mount Everest on Earth.

The white arrow show the downward grade. Several different flows can be seen throughout the picture, some confined to a central channel with smooth aprons of overflows on either side. Others are more broken and less coherent, and suggest that either the flows were inherently different, or are much older and have deteriorated with time.
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