Tag: Mars

More weird features and changes on Mars

1:31 pm

Some strange stuff on Mars
Click for full 2020 photo.

Overview map

Cool image time! The photo to the right, rotated, cropped, reduced, and annotated to post here, was taken on September 28, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Uncaptioned and labeled “Reticulate Bedform Change Detection on Arsia Mons West Flank,” it shows a whole bunch of strange features in addition to a change that occurred sometime in the past two years.

I think it also well illustrates in one image how alien Mars is.

The main features in this photo are what scientists have dubbed reticulate bedforms. These features, found mostly in the high elevations on the flanks of the giant volcanoes in the Tharsis Bulge to the west of Valles Marineris, are thought to be ancient dunes made of volcanic dust and debris that has solidified into an aggregate. These dunes are found with a variety of patterns.

Aggregates on the flanks are transported downslope by katabatic winds and form linear and “accordion” morphologies. Materials within the calderas and other depressions remain trapped and are subjected to multidirectional winds, forming an interlinked “honeycomb” texture. In many places on and near the volcanoes, light-toned, low thermal inertia yardangs and indurated surfaces are present.

The photo to the right appears to show all three patterns, even though it is located on the northwestern slopes of of Arsia Mons, the southernmost of the string of three giant volcanoes in the Tharsis Bulge. On the overview map to the right, this photo’s location is indicated by the white box. The black boxes indicate the location of all the pits caves that surround Arsia Mons which I have previously posted about on Behind the Black.

It is intriguing that, at least at this point, these particular reticulate bedforms on the slopes of Arsia Mons happen to be in a region where few cave pits have so far been identified. It could be that the conditions that form each are mutually exclusive. If you get pits on the slopes of Martian volcano you can’t have reticulate bedforms. Or maybe not all the pits have yet been located, or the flanks of the volcano has many more reticulate bedforms that I simply have not documented.

Either way, this particular cool image has two areas of interest, as noted by the white boxes above.
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On the edge of Mars’ giant volcanic flood plain

3:03 pm

Flows and pitted material on the edge of Mars' great volcanic flood plain
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on September 30, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Uncaptioned, it shows what the science team labels “Flows and pitted material in Terra Sirenum.”

Downhill is to the southeast, which means the pitted material forms some sort of filled terrain, with the surface eroded similarly everywhere. At a latitude of 32 degrees south, these flows could conceivably be glacial features. Are they?

A wider look might help answer that question. Below is a photo taken by MRO’s context camera, cropped and reduced to post here.
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Scientists: Gale Crater never had flowing surface water and was always cold

11:04 pm

The uncertainty of science: According to a new analysis of the data from Curiosity and Martian orbiters, scientists now propose that the climate in Gale Crater was never warm, but ranged from Icelandic conditions to far colder.

More importantly, the data suggests that none of chemistry there that required the presence of water was formed by fluvial processes, or flowing water. From the abstract:

We show that the geochemistry and mineralogy of most of the fine‐grained sedimentary rocks in Gale crater display first order similarities with sediments generated in climates that resemble those of present‐day Iceland, while other parts of the stratigraphy indicate even colder baseline climate conditions. None of the lithologies examined at Gale crater resemble fluvial sediments or weathering profiles from warm (temperate to tropical) terrestrial climates. [emphasis mine]

As must be repeated, the mineralogy found by Curiosity points to the presence of water once in Gale Crater, now gone. The initial assumption has always been that this water must have been liquid, as found on Earth. This new research is noting that the conditions show little evidence that liquid water ever existed, but was instead held in frozen lakes and glaciers.

In the coming years I think we are going to learn a lot about the glaciers and ice on Mars, both past and present, and how they reshaped Mars in ways that are alien to processes found on Earth.

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The freaky floor of Mars’ Hellas Basin

12:54 pm

The perplexing floor of Hellas Basin
Click for full image.

Today’s cool image takes us to the Death Valley of Mars, Hellas Basin, a place I like to call the basement of Mars. The photo to the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on September 28, 2020, and gives us another example of the very strange and inexplicable geological formations that are often found on the floor of Hellas.

The picture was taken not as part of any particular research project, but somewhat randomly for engineering reasons. In order to maintain the proper temperature of MRO’s high resolution camera, it must take images in a regular cadence. When large gaps in time occur between requested images, the camera team then picks locations to fill those gaps, sometimes randomly, sometimes based on a quick review of earlier wide angle images.

Sometimes these “terrain sample” images are quite uninteresting. More often they hold baffling surprises.

I think the photo to the right falls into the latter category. Though the terrain covered by the full image is largely flat and lacking in large features, the surface is strewn with perplexing small details.

The light streaks might be dust devil tracks, but why are they light here when such tracks are routinely dark everywhere else on Mars? What formed the many parallel small ridges? What caused the smooth solid patch near the photo’s center top? And why do the ridgelines at the western edge of that patch run in almost a perpendicular direction to the other ridges?

All a mystery, but then the floor of Hellas Basin is filled with such mysteries. Below is a list of some other cool images of the floor of Hellas, all weird and mystifying. Also below is an overview elevation map of Hellas Basin, with darker blue indicating the lowest elevations. The white cross marks the location of today’s photo.
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Antarctica data adds weight to hypothesis that glaciers shaped Mars

10:01 am

New data from an Antarctica ice core strengthens the hypothesis that the flow of glaciers, not liquid water, helped shape the meandering canyons on Mars.

The data was the discovery of the mineral jarosite deep within the south pole ice-cap. Jarosite needs water to form. Previously it was generally believed it formed in conjunction with liquid flowing water. On Mars, which appears to have lots of jarosite, scientists have struggled for decades to figure out how enough liquid water could have existed on the surface of Mars to produce it.

The discovery of jarosite deep inside the Antarctic ice cap now suggests that it can form buried in ice, not liquid water. According to the scientists,

the jarosite was born within massive ice deposits that might have blanketed [Mars] billions of years ago. As ice sheets grew over time, dust would have accumulated within the ice—and may have been transformed into jarosite within slushy pockets between ice crystals.

From the paper’s conclusions:

The occurrence of jarosite in TALDICE [in Antarctica] supports the ice-weathering model for the formation of Martian jarosite within large ice-dust deposits. The environment inside the Talos Dome ice [in Antarctica] is isolated from the Earth atmosphere and its conditions, including pressure, temperature, pH and chemistry, provides a suitable analogue for similar Martian settings. Dust deposited at Talos Dome is also similar to Martian atmospheric dust, being both mostly basaltic. Within thick ice deposits it is likely that the environment would be similar at Talos Dome and under Mars-like conditions since both settings would contain at cryogenic temperatures basaltic dust and volcanogenic and biogenic (for Antarctic only) sulfur-rich aerosols. … Considering this context, it is reasonable that the formation of jarosite on Mars involves the interaction between brines and mineral dust in deep ice, as observed in TALDICE. This mechanism for Martian jarosite precipitation is paradigm changing and strongly challenges assumptions that the mineral formed in playa settings.

Playa settings are places where there is standing liquid water, slowing drying away.

This result is another piece of evidence that ice and glaciers were the cause of the Martian terrain that to Earth eyes for decades was thought to have formed by flowing water. It also continues what appears to be a major shift on-going in the planetary science community, from the idea of liquid water on Mars to that of a planet dominated by glacial and ice processes.

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Back to Mars’ glacier country

1:11 pm

Tongue-shaped glacial flow on Mars
Click for full image.

The cool image to the right, rotated, cropped, and reduced to post here, was taken on November 3, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “Possible Tongue-Shaped Flow Feature in Protonilus Mensae.” There is no caption, so I will try to provide.

Protonilus Mensae is part of the long string of chaos terrain that runs about 2,000 miles along the transition zone between the southern cratered highlands and the northern lowland plains at about 30 to 40 degrees north latitude, and includes the other mensae regions dubbed Deuteronilus to the west and Nilosyrtis to the east. This region of Mars I like to call glacier country, because almost every high resolution photograph appears to show glacial features. To get an idea what I mean, take a gander at these past posts, their locations indicated by number in the overview map of Protonilus Mensae below:
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The strange moated mesas of the Kasei Valley on Mars

1:37 pm

Overview map

In showing my readers today’s cool image, I want to present it as it is seen by scientists, first from a far distance that with time increasingly zooms in to reveal mysteries on a very human scale.

The overview map to the right essentially gives us the view of Mars as seen by scientists following the Mariner 9 orbiter mission that began mapping the Martian surface in late 1971 after the conclusion of a global dust storm that had hidden its surface initially. As the first high resolution map of Mars, the orbiter revealed numerous puzzling and surprising features, including the largest volcanoes and canyons in the solar system. The orbiter also found that the red planet’s surface was comprised of two very different regions, the northern lowland plains and the southern cratered highlands.

The overview map, covering from about 13 degrees south latitude to about 34 degrees north latitude, shows us all but the southern cratered highlands. The white box in Kasei Valles is where today’s cool image is located. Both Kasai and Valles Marineris represent those giant canyons, all invoking to Earth eyes the possibility of catastrophic floods of liquid water sometime in the past.

Ascraeus Mons is the northernmost of the three giant volcanoes east of the biggest volcano of all, Olympus Mons. All sit on what scientists now call the Tharsis Bulge.

Chryse Planitia, where Viking-1 landed in 1976, is part of those northern lowlands that some scientists believe might have been once had an intermittent ocean sometime in the past. Today’s image is about 600 miles from the outlet into Chryse Planitia.

The geological mystery of all these features demands a closer look, something that scientists have been pursuing now for more than a half century.
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The pit caves of Mars: Can humans someday live in them?

1:24 pm

Four more pits in the Tharsis Bulge on Mars

It has been more than four months since my last report on the pits of Mars. Time to do another.

The collage to the right shows the four different pits photographed by the high resolution camera of Mars Reconnaissance Orbiter (MRO) since October. The links to each image are:

Like almost all the cave pits so far found on Mars, all are in the Tharsis Bulge of giant volcanoes to west of Valles Marineris. The overview map below shows these pits in the context of every other pit in this region that I have featured on Behind the Black.
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The slowly disappearing dry ice cap at Mars’ south pole

11:44 am

The Happy Face crater near Mars' south pole
Click for the 2020 full image.

Cool image time! The photo to the right of two images taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) was posted as a captioned image by the orbiter’s science team today.

This crater, dubbed the Happy Face Crater because of the shape of the blobby features within it, is located on the south pole ice cap of Mars, about 200 miles from the south pole itself.

Today’s caption noted how these pictures, taken nine years apart, illustrate the change going on at the Martian south pole.

The “blobby” features in the polar cap are due to the sun sublimating away the carbon dioxide into these round patterns. You can see how nine years of this thermal erosion have made the “mouth” of the face larger. The “nose” consisted of a two circular depressions in 2011, and in 2020, those two depressions have grown larger and merged.

While this caption noted the importance of studying these long term changes in order to understand the evolution of Mars’ climate and geology, it did not give the very specific discovery these changes suggest for Mars globally, a discovery that is actually very significant.

The two ice caps of Mars have some fundamental differences, all presently unexplained. The similarities are obvious. Both have permanent caps of water ice that are presently believed to be in a steady state, not shrinking or growing. Both each winter get covered by a thin mantle of dry ice that sublimates away completely with the coming of spring.

The differences are more puzzling, as shown by the maps of the two poles below.
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Curiosity checks out its wheels

1:55 pm

One wheel on Curiosity, as seen in July 2020 and January 2021
For full resolution images, go here and here for the
top image, and here and here for the bottom image.

Having finished a two week look at a sea of sand, Curiosity’ science team has resumed its journey east towards the higher slopes of Mount Sharp.

Before they started out however, they decided to aim the rover’s high resolution mast camera at Curiosity’s wheels to see how they are faring and whether any of the damage that occurred in the early days of the mission has worsened. The photo on the right compares what was seen this week with the damage on the same wheel as seen in July 2020. This is also the same wheel I have posted images of since September 2017.

Not only does there appear to be no appreciable new damage to this wheel in the six months since July, remarkably, a comparison between today’s image and the photo from September 2017, shows little change as well.

In the more than three years since that 2017 photo, Curiosity has crossed Vera Rubin Ridge, crossed the clay unit, climbed up the next ridge to take a look at the incredibly rough terrain of the Greenheugh Pedimont, and then continued across the clay unit on its way to higher and possibly more challenging terrain.

In all those travels it appears this particular wheel has fared rather nicely, accumulating in at least this part little new damage. This bodes well for the rover’s future, as the wheels have been a concern since Curiosity’s first two years on Mars, when engineers found they were experiencing more damage than expected. The travel techniques they have adopted since to protect the wheels appear to be working.

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More evidence Mars’s glaciers formed across many ice ages

11:26 am

The uncertainty of science: New research using the boulders found on the top of Martian glaciers has now strengthened the evidence that Mars must have undergone many previous ice age cycles going back as much as 800 million years, with those glaciers waxing and waning during each cycle.

This new data helps map the cycles earlier than 20 million years ago, which have been difficult to map out based solely on the orbital data available from Earth and from Mars orbit. The results suggest that before then there were from six to twenty additional cycles during the last 300 to 800 million years.

These numbers are decidedly uncertain. It is likely that there were many more cycles, as suggested by the many layers seen at the edges of the north and south polar ice caps.

Be aware as well that if you read the press release you should know that it falsely implies that this research is the first to map out these ice age cycles. This is not true. All this research has done is provide more evidence for cycles prior to 20 million years ago, cycles that scientists have long believed must have happened based on other data.

In the end, for us to map out the full climate history of Mars will require numerous ice core samples at the planet’s poles, something that will not be possible until people are living and working on Mars routinely.

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Mysterious colors on Mars, near the landing site of Europe’s rover

10:17 am

Mysterious colors on Mars
Click for full image.

Cool image time! Today the science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) released a new captioned image, which I have cropped and reduced to post here to the right.

The photo was taken October 12, 2020, and shows a small very colorful area on top of an isolated hill. To quote the caption, written by Sharon Wilson:

An isolated, elongated mound (about 1 mile wide and 3.75 miles long) rises above the smooth, surrounding plains. Horizontal layers are exposed at the northern end of the mound, and its surface is characterized by a very unusual quasi-circular pattern with varying colors that likely reflect diverse mineral compositions.

…The origin of this mound is unknown, but its formation may be related to the clay-bearing rocks in the nearby Oxia Planum region.

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