Tag: Mars

New paper: Underlying ice layer seen in Martian gullies at LOW mid-latitudes

2:18 pm

Snow on Mars?
Click to see full image.

In a paper just published, scientists are proposing that bright areas seen in the low mid-latitude gullies on Mars are the underground ice table newly exposed as surface dust is removed.

This paper is a reiteration in more detail of a previous presentation [pdf] by these same scientists at the 2019 the 50th Lunar and Planetary Science Conference in Texas and reported here in March 2019.

The image to the right, from the paper, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) in 2009, and has been cropped to post here. The white streaks are what the scientists propose is that exposed underground ice table. At 32.9 south latitude, this particular gully would be the closest to the equator that such an ice layer has been identified. All the previous ice layer discoveries have been in the ice scarps found at latitudes above 50 degrees. As the paper’s lead author, Aditya Khuller at Arizona State University, explained in to me in an email, “We believe we are seeing exposures of dusty ice that likely originated as dusty snow.” From their paper:

We suggest … that the light-toned materials are exposed H2O ice. … [T]he appearance, and then subsequent disappearance of these light-toned materials, suggests that they are some form of volatile, such as dusty ice, rather than dust alone. … [The appearance] of these light-toned materials is similar to the >100m thick, light-toned ice deposits exposed on steep mid-latitude scarps, indicating that these materials are probably also ice, with some amount of dust on, and within the ice.

The layer would have likely been laid down as snow during a time period (a long time ago) when the rotational tilt of Mars, its obliquity, was much higher than today’s 25 degrees. At that time the mid-latitudes were colder than the poles, and water was sublimating from the polar ice caps to fall as snow in the mid-latitudes.

The overview map below reveals some additional intriguing possibilities.
» Read more

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UAE releases first Al-Amal image of Mars

9:45 am

Al-Amal's first Mars image
Click for full image.

The new colonial movement: The leader of the United Arab Emirates (UAE) yesterday released on his twitter feed the first photo of Mars that was beamed back from its Al-Amal (“hope” in English) orbiter, taken shortly after achieving orbit.

That photo is to the right, cropped and reduced to post here. From the article at the link:

[The photo] was captured by Hope’s EXI instrument from an altitude of 24,700 km (15,350 miles) above the Martian surface at 20:36 GMT on Wednesday – so, one day after arriving at the Red Planet.

The north pole of Mars is in the upper left of the image. At centre, just emerging into the early morning sunlight, is Olympus Mons, the largest volcano in the Solar System. Look right on the boundary between night and day, the so-called terminator.

The three shield volcanoes in a line are Ascraeus Mons, Pavonis Mons, and Arsia Mons. Look east, to the limb of the planet, and you can see the mighty canyon system, Valles Marineris. It’s part covered by cloud.

Right now the spacecraft’s orbit is very eccentric, ranging from 600 to 30,000 miles above the Martian surface. After several orbital trims, Al-Amal will end up in an orbit about 14,000 by about 27,000 miles, with an inclination of about 25 degrees. From that high orbit it will then focus on studying the Martian atmosphere.

Thus, future images will likely be similar to this, global and mostly aimed at tracking visible phenomenon in the atmosphere (dust storms and clouds).

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Rover update: The rovers are coming! The rovers are coming!

12:52 pm

With the imminent landing on Mars of both the American rover Perseverance only days away on February 18th followed by China’s rover in April, I think it time for a new rover update, not only providing my readers a review of the new landing sites but a look at the most recent travels of Curiosity on Mars and Yutu-2 on the Moon.

Curiosity

Curiosity's view of the base of Mount Sharp, February 12, 2021
Click for full resolution image.

Overview map of Curiosity's most recent and future travels

The panorama above, made from four images taken by Curiosity’s right navigation camera on February 12, 2021 (found here, here, here, and here), looks south to the base of Mount Sharp, now only a short distance away. The yellow lines on the overview map to the right show the area this panorama covers. The white line indicates Curiosity’s previous travels. The dotted red line in both images shows Curiosity’s planned route.

The two white dots on the overview map are the locations of the two recurring slope lineae along Curiosity’s route, with the plan to get reasonable close to the first and spend some time there studying it. These lineae are one of Mars’ most intriguing phenomenon, seasonal dark streaks that appear on slopes in the spring and fade by the fall. There are several theories attempting to explain their formation, most proposing the seepage of a brine from below ground, but none has been accepted yet with any enthusiasm.
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Inexplicable ridges in Hellas Basin on Mars

2:07 pm

Sinuous ridge in Hellas Basin
Click for full image.

Time for some more cool but mysterious Martian images! The photo to the right, rotated, cropped, and reduced to post here, is the first of two images today, both of which show the ridges but of a completely different nature. Both are located in Hellas Basin in Mars southern hemisphere.

This first picture was taken on September 4, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows a sinuous complex that resembles to a remarkable extent a set of river tributaries, but is instead a set of raised ridges rather than a canyon system.

Scientists have found more than 10,000 miles of such ridges in the northern hemisphere in Arabia Terra, the most extensive transition zone between the southern highlands and the northern lowlands, and have dubbed them fossilized rivers. From a 2016 press release:

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low – in most other environments, the channels are worn away before they can become inverted. “The networks of inverted channels in Arabia Terra are about 30m high and up to 1–2km wide, so we think they are probably the remains of giant rivers that flowed billions of years ago. Arabia Terra was essentially one massive flood plain bordering the highlands and lowlands of Mars. We think the rivers were active 3.9–3.7 billion years ago, but gradually dried up before being rapidly buried and protected for billions of years, potentially preserving any ancient biological material that might have been present,” added Joel Davis.

Nor are such features on Mars limited to Hellas and Arabia Terra. For a particularly spectacular feature in the cratered highlands see this 2019 post.

The origin of these sinuous ridges in Hellas might have a similar origin as these other fossilized rivers. At present the bottom of Hellas, the deepest basin on Mars, is a place with little signs of ice. In the past there is evidence that lakes once existed here, so we cannot rule out water as a cause.

At the same time, Hellas was formed by a gigantic impact. One cannot dismiss the possibility of a volcanic origin, impact melt left over from the heat of that crash.

Today’s second ridge complex in Hellas looks far different.
» Read more

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China’s Tienwen-1 enters Mars orbit

8:42 am

The new colonial movement: China’s Tienwen-1, carrying an as-yet-unnamed lander/rover, successfully inserted itself into orbit around Mars early today.

With a successful Mars Orbit Insertion, the craft has entered a highly eccentric, equatorial capture orbit of the planet, and controllers will now spend two months undertaking initial activations and checkouts in Martian orbit for the primary science mission while altering the craft’s orbit from equatorial to polar.

In April 2021, the lander, with the rover inside, will detach from the orbiter and prepare for Entry, Descent, and Landing. Prior to launch, 23 April 2021 was given as the target landing date.

The landing location is within Utopia Planitia and will — if the orbit insertion burn is completed successfully — utilize a combination of aerobraking, parachute descent, retrorocket firing, and airbag deployments to achieve a soft touchdown on the Martian surface. After landing, the rover will be deployed — ideally on the same day — to begin a planned 90 Sol (Martian day) mission to categorize the local environment.

The suspected landing site in Utopia Planitia is at about 25 degrees north latitude. Though it is in the northern lowland plains, this latitude places it south of the latitudes (greater than 30) that scientists now believe ample ice likely exists underground but accessible. The lander/rover carries radar equipment capable of detecting evidence of underground ice, and will look nonetheless. If it finds any, this will be a significant discovery.

Two down, one to go. Next week, on February 18th, the American rover Perseverance will attempt its landing in Jezero crater.

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Another “What the heck?!” image on Mars

2:53 pm

A
Click for full image.

Today’s cool image, taken on September 2, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped and reduced to post here, is one that I will make very little attempt to explain. It falls into a category I call “What the heck?!” The uncaptioned website labels this “Ringed Ridges in Kasei Valles”, which merely describes what we see.

This isn’t an impact crater. The rings don’t fit any morphology I’ve ever seen for such features.

Could we be looking at some type of glacial feature? The latitude, 29 degrees north, makes this unlikely but possible. Even so, it sure doesn’t look like it. The ripples in the center and between the ridges are sand dunes, not glacial features.

Might this be a volcanic vent, with the concentric ridges marking multiple eruptions? Maybe, but if so I’ve never seen any volcanic vent or caldera that looked quite like this.

The overview map below gives some context, but hardly explains anything.
» Read more

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Musk: Starlink to go public once operational

8:48 am

Capitalism in space: According to a tweet by SpaceX founder Elon Musk, once the Starlink internet satellite constellation is operational and has a “reasonable well” cash flow it will issue and IPO and become a publicly traded stock.

“SpaceX needs to pass through a deep chasm of negative cash flow over the next year or so to make Starlink financially viable,” Musk wrote in another tweet. “Every new satellite constellation in history has gone bankrupt. We hope to be the first that does not.”

Based on the company’s pace of launching satellites and rolling out service, this moment could occur as early as late this year. More likely it will occur in mid-22.

I would also expect that stock to quickly rise in value, and based on the history of all of Musk’s companies, will continue to rise thereafter. Expect also that a significant portion of the investment capital that Starlink will raise will be used to finance the development of Starship and Super Heavy, because Starlink will need that larger rocket to maintain its satellite constellation.

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UAE’s Hope or Al-Amal Mars Orbiter orbital insertion

8:31 am

UPDATE: The probe has apparently achieved orbit.

The new colonial movement: The United Arab Emirates’ (UAE) Mars orbiter, Hope, or Al-Amal in Arabic, is about to insert itself into orbit around the red planet, with that insertion to be confirmed by 11:08 (Eastern).

If you want to watch, I have embedded the live stream below the fold. A warning: The insertion is a relatively interesting event to watch, as the orbiter works autonomously and the signal confirming it happened arrives after the event. Most of the stream is propaganda for the UAE.
» Read more

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The Icy Surface of Mars

1:04 pm

The extent of ice on Mars

Two newly published science papers in the past few days have once again reinforced the growing evidence that much of Mars from 30 degrees latitude to its poles is very icy, with much of that ice found close to the surface.

The map above, adapted and annotated by me from figures 4 and 12 of one of those papers (“Widespread Exposures of Extensive Clean Shallow Ice in the Mid‐Latitudes of Mars”), show the areas on Mars where the evidence suggests ample and easily accessible ice, underground but close to the surface.

The red dots and diamonds indicate recent impact craters that temporarily exposed the underground ice layer that would normally not be visible. The white dots and diamonds indicate ice scarps with visible ice layers in their cliff faces. The size of these locations is greatly exaggerated.

The two hatched lines at 30 degrees latitude, north and south, indicate the closest to the equator that scientists have detected evidence of glacial ice. It is also the closest to the equator that the second new paper, “Water Ice Resources Identified in Martian Northern Hemisphere “, has found evidence of underground ice in the north. From the abstract of this second paper:
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Tianwen-1 takes first picture of Mars

12:48 pm

Mars as seen by Tianwen-1 for the first time
Click for full image.

The new colonial movement: China’s Tianwen-1Mars spacecraft has taken its first picture of Mars, cropped and reduced to post here to the right.

The photo shows Valles Marineris as the darker splotch in the center-right of the hemisphere, with the northern lowland plain that this canyon feeds into, Chryse Planitia, the triangular dark area to the north east. Both Viking-1 and Mars Pathfinder landed in this region. The whitish border area on the triangle’s eastern flank is the area that Europe’s Rosalind Franklin rover will hopefully land in ’23.

The whitish area that caps the north pole is likely the annual mantle of dry ice that covers the planet’s polar regions down to about 60 degrees latitude each winter. Right now it is early spring in the northern hemisphere, and that mantle has only begun to sublimate away. In another few months that mantle will disappear entirely, exposing the terrain below it.

Finally, the very bright edge on the planet’s eastern limb is either caused by a cloud layer, or is simply an over-exposure. Hard to say which.

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The new invasion of Mars begins next week!

10:13 am

In the next two weeks three spacecraft will arrive at Mars, including two orbiters and two rovers. This post is simply a heads up so that my readers will know what to expect and when to expect it.

First, we have the arrival in Mars orbit of the United Arab Emirates’ (UAE) Hope orbiter on February 9th at 10:30 am (Eastern). The spacecraft was built in a partnership with U.S. universities and the UAE. Once in orbit it will focus on studying the Martian atmosphere.

Next will arrive China’s Tianwen-1 orbiter on February 10th. The exact time it will do its engine burn to enter orbit has not been announced, as far as I can tell. Once in orbit it will begin a four month reconnaissance of the landing site for its presently unnamed rover, which will descend to the surface in May.

Finally, on February 18th at 12:55 am (Pacific) the American rover Perseverance will land in Jezero Crater on Mars. Essentially an upgraded copy of the Curiosity rover, it will land in the same way, lowered by cables from its re-entry sky crane rocket above it. It will then spend years studying the geology of Mars, while also storing samples that a later mission can recover and return to Earth.

All in all February is going to be an exciting month for the exploration of Mars. Stay tuned for some cool stuff!

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New theory to explain the Martian seasonal streaks

9:22 am

The uncertainty of science: Scientists have proposed a new explanation for explaining the Martian seasonal streaks called recurring slope lineae that appear each spring and then fade over time.

Lineae, while unique to Mars, are different than the other similar Martian feature called slope streaks, which are not seasonal and have a somewhat different appearance and morphology.

This new proposal refines some of the past ideas for the seasonal cause of lineae.

Previous ideas suggested that liquid debris flows or dry granular flows caused this movement. Neither model can completely account for the seasonal martian flow features known as Recurring Slope Lineae (RSL). The team alternatively hypothesizes that small-scale ice melting in the near-surface regolith is causing changes at the surface that make it vulnerable to dust storms and wind. As a result, the RSL features appear and/or expand on the surface of Mars today. Further, the team believes that the thin layers of melting ice result from interactions between underground water ice, chlorine salts, and sulfates, which create an unstable, liquid-like flowing slush instigating sinkholes, ground collapse, surface flows, and upheave.

…Previous studies have suggested RSL are related to chlorine salts and noted their occurrence in regions of high sulfate outcrops. The current study extends these observations with a near-surface cryosalt activity model based on field observations and lab experiments. However, the exact mechanism of RSL formation on Mars still remains a mystery. [emphasis mine]

The mainstream press will make a big deal about this, but it really does nothing but add some nuance to previous theories. We really still do not know what causes lineae, as the highlighted text above notes.

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Ten finalists in public Chinese contest to name Mars rover

3:15 pm

The new colonial movement: The Chinese public vote to pick the name of the Mars rover presently flying to Mars on its Tianwen-1 orbiter has now been narrowed to ten finalists.

The public can now vote for their favorites from a shortlist of 10 names for the Tianwen-1 mission rover.

The 10 names — Hongyi, Qilin, Nezha, Chitu, Zhurong, Qiusuo, Fenghuolun, Zhuimeng, Tianxing and Xinghuo — are taken from ideas including Chinese mythological figures, Confucian concepts and legendary animals.

Notably Hongyi, from the Confucian Analects, can be translated to “persistence” or perseverance, giving a similar meaning to the NASA Perseverance rover also heading for Mars. Others meanings include:

Zhurong: a god of fire
Qilin: a Chinese unicorn
Chitu: red rabbit
Qiusuo: to explore, referencing an ancient poem
Zhuimeng: to pursue a dream
Nezha: a mythological hero
Fenghuolun: Nezha’s weapons
Tianxing: referring to the motion of celestial bodies
Xinghuo: spark

Personally, I hope they pick Chitu (Red Rabbit), as that matches nicely with the name of China’s lunar rover, Yutu-2 (Jade Rabbit).

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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.
» Read more

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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.
» Read more

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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.
» Read more

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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.
» Read more

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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.
» Read more

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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
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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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InSight scientists give up on heat sensor mole

9:25 pm

After another failed attempt earlier this month to dig with the German-made mole on the InSight Mars lander, the science team has decided to abandon all further efforts.

After getting the top of the mole about 2 or 3 centimetres under the surface, the team tried one last time to use a scoop on InSight’s robotic arm to scrape soil onto the probe and tamp it down to provide added friction. After the probe conducted 500 additional hammer strokes on 9 January, with no progress, the team called an end to their efforts.

This means the heat sensor, one of the two instruments carried by InSight, is also a failure, and will not be able to provide any data about the planet’s interior temperature.

From the beginning InSight appears to have been a poorly run and badly chosen project. Other than a weather station, it carried only two instruments, a seismometer and a heat sensor. Its launch was delayed two years when the French attempt to build the seismometer failed and JPL had to take over, fortunately with success. Now the failure of the German-made mole has made the heat sensor a failure.

To send a lander to Mars at a cost of a billion dollars with so little payoff seems in hindsight to have been bad use of money. Plenty of other NASA planetary missions have done far better for far less.

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Craters in slush on Mars

1:11 pm

Dust devil steak across a slushy plain on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on October 27, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was taken not for any particular research project, but as one of the periodic images the camera team needs to take maintain the camera’s proper temperature. When they need to do this, they often will take a picture in an area not previously viewed at high resolution. Sometimes the image is boring. Sometimes they photograph some geology that is really fascinating, and begs for some young scientist to devote some effort to studying it.

In this case the photo was of the generally featureless northern lowland plains. What the image shows us is a scattering of impact craters that appear to have cut into a flat plain likely saturated with ice very close to the surface.

How can I conclude so confidently that these craters impacted into ice close to the surface? The location gives it away.
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The target landing ellipse on Mars for Perseverance

2:59 pm

Perseverance's landing ellipse on Mars
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In just over a month, on February 18, 2021, the American rover Perseverance will come screaming through the thin atmosphere of Mars at a speed of over 12,000 miles per hour to hopefully land successfully in Jezero Crater.

The map to the right, cropped and reduced to post here, was released last week by the Perseverance science team and shows the landing ellipse in that crater. It also shows the much larger landing ellipses of previous landers/rovers. As they noted,
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The colorful and bright knobs of Ariadnes Colles on Mars

1:50 pm

Colorful and bright knob in Ariadnes Colles
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Today’s cool image gives us a sample of the strange colorful hills in an even stranger knobby depression on Mars called Ariadnes Colles. The photo to the right, cropped and color enhanced to post here, was taken on September 10, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It focuses on just one of those colorful hills. The color strip only covers the western half, which is why that is the only part of the hill in color.

Ariadnes Colles is a patch of chaotic terrain 110 by 100 miles in size, located in the southern cratered highlands due south of Mars’s volcano country, at latitude 34 degrees south. What makes this particular patch of chaos distinct from the many others on Mars is that the hills, knobs, and mesas within it are routinely bright and colorful, compared to the darker surrounding terrain. Moreover, as noted in this Mars Express press release for images of Ariadnes Colles from that orbiter,

In contrast to other chaotic terrains … Adrianes Colles is not a water-source region. It is still debated, therefore, whether Ariadnes Colles was formed by the action of water or wind.

The darker material in the southern areas is most likely sand or volcanic ash; some slopes of the flat-topped features have been covered by this dark material that was blown up on the slopes.

The sand or volcanic ash most likely come from the Medusae Fossae Formation several hundred miles to the north, the largest volcanic ash deposit on Mars. The colors on the hill likely come from a variety of minerals.

The overview map below shows the entire patch, with the location of the hill above indicated by the white dot in the red rectangle that shows the full image location.
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Partly engulfed Martian craters

5:01 pm

An engulfed crater on Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 31, 2020. It shows a crater that appears buried in a sea of material so that pretty much the only thing visible is top of its rim.

The full image shows a second larger crater to the northwest that looks the same. In both cases the material fills the craters also fills the surrounding terrain.

Yet, both craters appear to be surrounded by a faint skirt of uplifted material.

What caused this situation?
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