Tag Archives: MRO

A Martian shoreline?

Collapsing cliff in Tempe Fossae

Cool image time! The image on the right, reduced and cropped to post here, was part of the August 31 image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO). (Click on the image to see the full image.) It shows a slowly separating cliff feature in a region dubbed Tempe Fossae

As part of that monthly mass release, no caption was provided for this image. However, we can gain some understanding by looking at the larger context.

Tempe Fossae is located at the margins between the low flat northern plains and the high southern highlands. The location is also part of the vast drainage region to the east of Mars’ gigantic volcanoes. This is obvious from the overview image below and on the right. The location of this image is indicated by the white cross.

Mars overview

In this area of that drainage the canyons appear to follow southwest to northeast trending fault lines. Tempe Fossae is one of the smaller of these canyon complexes. All however appear to drain out into the northern plains.

Most of the MRO images of features in this area focus on the canyon cliffs. This image however focused on this one isolated small cliff in the middle of the canyon. To my eye it appears that these features document the slow drying of that vast intermittent ocean in Mars’s northern plains. The cliff is actually two steps, with the higher one appearing to mark an older shoreline. The lower cliff is abutted by a low flat area where it appears as if there had once been ponded water, now dried.

close-up of cracked area

The cracks in the cliff itself suggest it is slowly breaking apart and falling down towards that low flat area. In fact, the entire feature reminds me of the sand cliffs that are sometimes found along shorelines. The sand is not very strong structurally, and with time sections will separate and then fall down. The image to the right zooms in on this cracked region. The presence of sand dunes reinforces my impression.

I imagine that as the water drained down from the glaciers on the sides of the volcanoes and filled that intermittent sea, the shoreline regions would have had the most water. At Tempe Fossae the canyons might have been partly filled. As the water level drained out and lowered, first the upper cliff edge was exposed, then the lower. The draining water probably helped created these cracks as it flowed down through them.

Finally, the last remaining pits of water ponded at the base of the cliff, eventually drying out. With time, the weakly structured sand cliffs, already carved partly by the flowing water, began to slump apart and fall downward, producing the cracks we now see. I expect that some time in the near future, on geological time scales, there will be a landslide and the outer section will collapse downward.

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Baby volcanoes on Mars

Pitted cones on Mars

Most people are very aware of Mars’ giant volcanoes. This week the science team for Mars Reconnaissance Orbiter (MRO) decided to highlight instead a location on Mars filled with relatively tiny volcanoes. The image on the right is only one small section from the full image, and shows some of these pitted cones, as well the strange nearby badlands. From their caption:

The origins of these pitted mounds or cratered cones are uncertain. They could be the result of the interaction of lava and water, or perhaps formed from the eruption of hot mud originating from beneath the surface.

These features are very interesting to scientists who study Mars, especially to those involved in the ExoMars Trace Gas Orbiter mission. If these mounds are indeed mud–related, they may be one of the long sought after sources for transient methane on Mars.

The age of these pitted cones is not known. They might be still active, or have sat on Mars unchanged for eons.

Overview map

As always, context is crucial for gaining a better understanding of what we are looking at. The map on the right shows that these particular cones, indicated by the white cross, are located in an area of those plains dubbed Chryse Planitia, part of the vast northern plains of Mars, an area where some scientists think an intermittent ocean might have once existed. As you can see, this is also the region that took most of the apparent drainage running off the slopes of the planet’s giant volcanoes.

Nor are these cones unique in this region. MRO has taken a good scattering of images at this general location (41 degrees north, 332 degrees east), and throughout the surrounding terrain are many more of these pitted cones.

If these cones are a source of the transient methane on Mars, then the Trace Gas Orbiter should eventually see a concentration of methane above them. This would not prove them to be the source, but it would make them a much more intriguing target for a later rover mission.

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Looking for Marsquakes

After eight and a half years of study of one particular very young fault system on Mars using high resolution images from Mars Reconnaissance Orbiter, scientists have found no evidence that any quakes occurred there in that time.

The team studied images of Mars’s surface over nearly a decade to look for changes that might have been caused by marsquakes. The researchers used images of Mars’s surface from the High Resolution Imaging Science Experiment (HiRISE) and applied Co-registration of Optically Sensed Images and Correlation (COSI-Corr)—software that has been validated to track terrestrial glaciers, landslides, and quakes on Earth, as well as dune movement on Mars itself—to hunt for signs of displacement near fault zones.

The researchers focused on the Cerberus Fossae fault system, the youngest fault system on the Red Planet and thus the most likely to still be active. They used the average coregistration performance of each study image to determine that this method should be able to detect fault slip rates of 0.1–10 millimeters a year.

The team identified only one displacement signal that could have been interpreted as evidence of a marsquake—but dismissed it as the result of a topographic artifact. Their results suggest that no seismic movement occurred in the Cerberus Fossae area over the course of the study, which spanned 8.5 Earth years’ worth of images from the planet.

This suggests, but does not prove, that Mars has very few quakes. We shall know more when InSight lands on Mars on November 26.

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The search for Mars Polar Lander

A small section where Polar Lander might have crashed

In December 1999 the U.S. lander Mars Polar Lander was to set down near the southern polar cap of Mars. After an almost routine eleven month journey to Mars, all efforts to contact the spacecraft after its landing failed. A NASA review eventually concluded that the spacecraft had prematurely shut down its landing engines while the spacecraft was still far above the surface, and had therefore crashed to the ground.

Since then there have been extensive efforts to locate the lander’s remains on the surface, all to no avail. Though Mars Global Surveyor, in orbit at the time, tried to find it, its resolution was not sufficient. In recent years Mars Reconnaissance Orbiter (MRO) has taken several dozen high resolution images of the estimated landing area, two of the most recent were included in the August 2018 image release. The image on the right is a cropped section of one of those images, illustrating the difficulty of the search. (If you click on the image you can explore the full version.) The other image is quite similar.

As the southern polar cap shrinks and grows seasonally, it produces endless numbers of black spots from the release of underground dust as the carbon dioxide dry ice sublimates into gas. Moreover, the growth and retreat of the dry ice cap changes the landscape, periodically covering any remains of the rover as well as quickly removing many of the ground disturbances that the crash might have caused. In the almost two decades since the lander’s crash landing, about ten Martian years have passed, meaning that cap has melted and frozen ten times over this region in that time.

Images taken by MRO of Mars Polar Lander landing area

The image on the right shows the footprint of all the images that MRO has so far taken of the Mars Polar Lander landing area. If you are ambitious and want to get your name in the news, all you have to do is spend some time combing through those images and find the lander there. Every one of these images is available for public download at full resolution. Go to HiRise image archive, hover your mouse over latitude 77 degrees south, longitude 166 degrees east, and click several times to zoom in. You then change the selector icon at the top from “+” to “the arrow”. When next you click on any portion of that footprint it will show you a bunch of the images taken, all of which you can now download and inspect.

If you are successful and find the lander, please let me know. It would be nice to make that announcement here on Behind the Black.

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Inexplicable high latitude Martian terrain

Inexplicable high southern latitude Martian terrain

Strange image time! The image on the right, reduced in resolution to post here, comes from the August 1, 2018 image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). (If you click on the image you can see the full resolution version.) I have not cropped this image at all, so that you can see all of its swirling terrain.

This image did not come with a caption. The image site merely describes this terrain as having an “interesting morphology.” The location, in the very high southern latitudes (78 degrees south) just outside the southern rim of a very large crater, provides a slight explanation, as the growth and retreat of the Martian carbon dioxide polar caps is known to create very strange landforms. These swirling flows are obviously an example of one such landform.

The crater rim is just off of the top of the image and parallel with it. Therefore, the apparent erosional flows going around the hills and mesas are running parallel to the rim, not down from it. The black specks scattered about are probably points where dust was released as the carbon dioxide turned from ice to gas, a process that at the high latitudes on Mars often causes what planetary scientists call “spiders.”

I will not even try to make a guess at the process that formed what we see here. The image itself was taken on June 16, 2018 as part of a seasonal monitoring effort, which means scientists expect there to be changes occurring here from year to year as the polar cap shrinks and grown. An almost identical image had been taken two years ago, on December 18, 2016, and shows almost no black specks, probably because of the different time in the Martian year. A much closer comparison of both high resolution images would be necessary to tease out any more subtle changes.

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A strange bulge on Mars

Pollack Crater

Cool image time! The image on the right is not the cool image, but a context image of 59-mile-wide Pollack Crater, located slightly south of the Martian equator in the planet’s southern cratered highlands. What makes this crater intriguing to planetary scientists, and has prompted them to take many images over the decades, is the bulge in the southwest part of the crater’s floor. You don’t normally see a rise off-center like this inside craters. If there were any peaks, you’d expect them to be in the center, formed during the impact, when the crater floor melts and acts more like water in a pond when you drop a pebble into it, forming ripples with an uplifting drop in the dead center.

It therefore isn’t surprising that planetary scientists have taken a lot of pictures of this bulge, going back to the Mariner 9 orbiter in 1972, which first discovered it. Scientists then dubbed it “White Rock” because in the first black & white images it looked much brighter than the surrounding terrain. Later color images revealed that it is actually somewhat reddish in color, not white. As noted at this Mars Global Surveyor webpage,
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Cryptic terrain in Martian high southern latitudes

Cryptic terrain in Reynolds Crater near Mars south pole

Cool image time! The image on the right is a small cropped section from a larger image taken of the floor of Reynolds Crater, near the margins of the Martian southern polar carbon dioxide icecap.

The image was part of the August 1, 2018 image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO) and was taken on July 5, 2018. Because that was during the peak of now clearing global dust storm, a large majority of MRO’s images were obscured. Only images taken at high latitudes appeared clear and sharp.

The image link, which has no caption, calls this “cryptic terrain.” Since this is at the margin of the polar cap, the white areas are almost certainly still-frozen dry ice. The white strip down the center of the image appears to be a low drainage gully, made even more evident on the full image.

What are the dark spots however? These are probably related to the dark spiders that appear wherever the carbon dioxide starts to melt and evaporate into gas, releasing the darker dust from below to coat the surface. The dark spots in this image are probably that same darker dust, but why it is scattered about as spots and splotches is a mystery. It does appear that the dark areas more completely cover the higher terrain, but why and if so is definitely unclear.

Back in 1999 I attended a press conference just prior to the failure of Mars Polar Lander. One of the mission’s investigators explained that, based on the orbiter images available at the time, they expected the lander to see some very weird land forms once it reached the surface, shaped in ways that are not seen on Earth. Unfortunately, contact with the spacecraft was lost just before it entered the Martian atmosphere, and was never recovered.

This image however remains me of that scientist’s lost expectation. The seasonal growth and retreat of the Martian icecaps will likely create some strange geology, which is only hinted at in this particular MRO image.

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Mars dust storm blocks Mars Reconnaissance Orbiter images

In my normal routine to check out the periodic posting of new high resolution images from Mars Reconnaissance Orbiter (MRO), the August 1 update brought what at first was a disturbing surprise. If you go to the link you will see that a large majority of the images show nothing by a series of vertical lines, as if the high resolution camera on MRO has failed.

Yet, scattered among the images were perfectly sharp images. I started to look at these images to try to figure out the differences, and quickly found that the sharp images were always of features in high latitudes, while the blurred images were closer to the equator.

The August 1 image release covered the June/July time period, when the on-going Martian dust storm was at its height. The images illustrate also where the storm was most opaque, closer to the equator.

The next few updates, which occur every three weeks or so, should show increasing clarity as the storm subsides. And the storm is subsiding, according to the latest Opportunity update. The scientists have still not re-established contact with the rover, and do not expect to for at least a month or more, but they are finding that the atmospheric opacity at Endeavour Crater seems to be dropping.

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Another skylight entrance pit found on Mars

Pit in Hephaestus Fossae

Cool image time! In my routine monthly review of the hundreds of new images released from the high resolution camera on Mars Reconnaissance Orbiter (MRO), I came across another most intriguing geological feature, the image of which is posted to the right, after cropping.

As the scale shows, the pit is about 300 feet across. Calculating the pit’s depth would require someone with better math skills than I. The website provides information about the sun angle, which can be used to extrapolate the shadows and then roughly calculate the depth.

The most fascinating aspect of this pit is the impression of incredible thinness for the pit’s overhung edges. All of the pit’s edges appear significantly overhung, and the thickness of the overhang seems incredibly paper-thin. This thinness is likely only an illusion, though in Mars’s light gravity it is perfectly possible for the overhang to be far thinner and more extended than anything you would find on Earth.

The image itself is in color, though the only color visible is within the pit itself. In that blueness at the base it seems to me that there is a pile of dust/debris, but once again, that conclusion should not be taken very seriously.

If you take a look at the full image, what is impressive is the bland flatness of the surrounding terrain. There is no hint that there might be underground passages hidden here. While most of the scattered craters are probably impact craters, many (especially those with unsymmetrical shapes) could be collapse features indicating the presence of underground voids. None however is very deep. Nor is there any other pits visible.

Below is a global map of Mars with the location of this pit indicated by a black cross. It is just on the edge of the transition zone between the lower northern plains and the southern highlands, where the shoreline of an intermittent sea is thought by some scientists to have once existed. This is also an area where not a lot of high resolution images have been taken, mostly because of its apparent blandness as seen in previous imagery.

This image demonstrates however that Mars is going to have interesting geology everywhere, and that we won’t really know it well until we have explored it all.
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A dark dust avalanche on Mars

No dust avalanche

After dust avalanche

Cool image time! The two images to the right, both cropped to post here, were taken six years apart by Mars Reconnaissance Orbiter (MRO) of the western lava slopes of the giant volcano Olympus Mons. They show the appearance of a dark dust avalanche during the interim. As noted by members of the MRO science team.

Dust avalanches create slope streaks that expose darker materials usually hidden below a lighter-toned layer. Cascading fine-grained material easily diverts around boulders or alters direction when encountering a change in slope. The dark steak … is approximately 1 kilometer in length that we didn’t see in a previous image. Past avalanche sites are still visible and fading slowly as dust settles out of the atmosphere and is deposited on the dark streaks over time.

We also see boulders and their shadows that are a meter or greater in size. Movement of any of these boulders down the slope could trigger future avalanches.

The appearance of these Martian dark streaks on slopes is actually not uncommon. As more pictures are taken of Mars scientists are beginning to accumulate a large number all across the Martian surface.

What I find fascinating is the wet look of these dark streaks. Below is a close-up of the new avalanche, near its head.
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Spiders on Mars!

spiders on Mars

Cool image time! Today’s release of new captioned images from the high resolution camera on Mars Reconnaissance Orbiter (MRO) included a wonderful image of the melting carbon dioxide cap of Mars’s south pole. On the right is a cropped portion of the full image, showing what the MRO scientists nickname spiders, features that appear as the CO2 begins to turn into gas.

But these aren’t actual spiders. We call it “araneiform terrain,” to describe the spider-like radiating channels that form when carbon dioxide ice below the surface heats up and releases. This is an active seasonal process we don’t see on Earth. Like dry ice on Earth, the carbon dioxide ice on Mars sublimates as it warms (changes from solid to gas) and the gas becomes trapped below the surface.

Over time the trapped carbon dioxide gas builds in pressure and is eventually strong enough to break through the ice as a jet that erupts dust. The gas is released into the atmosphere and darker dust may be deposited around the vent or transported by winds to produce streaks. The loss of the sublimated carbon dioxide leaves behind these spider-like features etched into the surface.

The image above shows older spiders, formed during past seasonal events. If you click on the image you can see the full image, which shows darker spiders produced by this season’s cycle.

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The mysterious chaos terrain of Mars

In one of my weekly posts last month (dated May 14th) delving into the May image release from Mars Reconnaissance Orbiter’s (MRO) high resolution camera, I featured an image of what planetary geologists have labeled chaos terrain, a hummocky chaotic terrain that has no real parallel on Earth but is found in many places on Mars.

This month’s image MRO release included two more fascinating images of this type of terrain. In addition, the Mars Odyssey team today also released its own image of chaos terrain, showing a small part of a region dubbed Margaritifer Chaos. Below, the Mars Odyssey image is on the right, with one of the MRO images to the left. Both have been cropped, with the MRO image also reduced in resolution. The full MRO image shows what the MRO science team labels “possibly early stage chaos” on the rim of a canyon dubbed Shalbatana Vallis.

young chaos in Shalbatana Vallis

Margaritifer Chaos

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The epic lava flows of Olympus Mons

Lava flows off of Olympus Mons

The eruption of Kilauea volcano in Hawaii has garnered a lot of deserved press coverage, having added at least a 200 acres of new land and destroyed at least 700 homes. Similarly, the recent violent eruption of a volcano in Guatemala, killing 100 people in its wake, has also gotten much deserved news coverage.

The magnitude of both however would pale in comparison to the stupendous eruption that occurred several hundred million years ago at the solar system’s largest volcano, Olympus Mons on Mars. While Kilauea is about 100 miles across, Olympus Mons is about 370 miles wide, and is so large that because of the curvature of Mar’s surface it is literally impossible for a viewer on the ground to actually see the volcano, in its entirety.

Both volcanoes are shield volcanoes, however, which means the lava flows don’t necessarily come from the caldera, but often from vents on the volcano’s slopes. Eruptions might be violent, but they generally do not involve the powerful explosive force of the sudden eruption, as seen in Guatemala and at Mount St. Helens in 1980 in the U.S. Instead, the lava seeps out steadily and continuously, an unstoppable flow that steadily overwhelms the surrounding terrain.

Olympus Mons

The flows that created Olympus Mons however were an epic event probably lasting millions of years, which brings us to this post. In the June release of Mars Reconnaissance Orbiter high resolution images, I found the image above, cropped and reduced in resolution to post here. It shows lava flowing down off one of the many escarpments on the slopes of Olympus Mons. This is not at the edge of the volcano’s shield, but just inside it. The map at the right, created using the archive of MRO’s high resolution camera, indicates the location of this flow, shown by the left light blue rectangle on the southeast slope of the volcano’s shield. The red rectangles show all the other images MRO has taken of Olympus Mons.

The scale of the MRO image above gives an indication of how big that eruption at Olympus Mons was.
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Another intriguing pit on Mars

pit on Mars

Cool image time! In the June release of images from the high resolution camera on Mars Reconnaissance Orbiter, I came across the image on the right, cropped slightly to post here, of a pit in a region dubbed Hephaestus Fossae that is located just at the margin of Mars’s vast northern plains.

Below and to the right is an annotated second image showing the area around this pit. If you click on it you can see the full resolution image, uncropped, and unannotated.

wider view of pit

The scale bar is based on the 25 centimeter per pixel scale provided at the image link. Based on this, this pit is only about ten to fifteen meters across, or 30 to 50 feet wide. The image webpage says the sun was 39 degrees above the horizon, with what they call a sun angle of 51 degrees. Based on these angles, the shadow on the floor of the pit suggests it is about the same depth, 30 to 50 feet.

The shadows suggest overhung walls. This, plus the presence of nearby aligned sinks, strongly suggests that there are extensive underground passages leading away from this pit.

For a caver on Earth to drop into a pit 30 to 50 feet deep is nowadays a trivial thing. You rig a rope (properly), put on your vertical system, and rappel in. When you want to leave you use that same vertical system to climb the rope, using mechanical cams that slide up the rope but will not slide down.

On Mars such a climb would be both easier and harder. The gravity is only one third that of Earth, but the lack of atmosphere means you must wear some form of spacesuit. Moreover, this system is not great for getting large amounts of gear up and down. Usually, people only bring what they can carry in a pack. To use this Martian pit as a habitat will require easier access, preferable by a wheeled vehicle that can drive in.

The pit’s location however is intriguing. The map below shows its location on a global map of Mars. This region is part of the Utopia Basin, the place with the second lowest elevation on Mars.
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New impact craters on Mars

New impact crater on Mars

Cool image time! The high resolution camera on Mars Reconnaissance Orbiter (MRO) keeps finding recent impact craters, all of which the science team try to monitor periodically to see how the surface evolves over time. The image on the right, cropped to post here, is one such crater, the image taken in January 2018 and released with as one of the captioned images from this month’s image catalog release. If you click on the image you can see the full picture.

What is notable about this particular impact are the colors.

The new crater and its ejecta have distinctive color patterns. Once the colors have faded in a few decades, this new crater will still be distinctive compared to the secondaries by having a deeper cavity compared to its diameter.

Those colors of course have importance to researchers, as they reveal the different materials found beneath the surface at this location, normally hidden by surface dust and debris.

Nor is this the only impact crater revealed in this month’s image release. Earlier in the month the science team highlighted an image that captured two small impacts. While all three of these impacts are in the general region called Elysium Planitia, they are not particularly close to each other. They are however surrounding the landing site for the InSight lander now heading to Mars. This last link takes you to my January 28, 2018 post detailing some information about this landing site, and also includes another recent crater impact, found at the center of the landing zone.

It is not clear if these recent impacts are related to each other. As noted by Alfred McEwen of the science team, “Often, a bolide breaks apart in the atmosphere and makes a tight cluster of new craters.” It could be that all these recent impacts came from the same bolide, which is why there appear to be a surplus of them in Elysium Planitia.

Then again, our surface survey of Mars is very incomplete. These impacts could simply be marking the normal impact rate for Mars. We will not know until we have completed a detail survey of all recent impacts on Mars, and have been able to date them all.

Who wants to do it?

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Chaos on Mars

chaos terrain

Cool image time! The image on the right, cropped and reduced in resolution to post here, shows an area on Mars that geologists have dubbed “Chaos Terrain.” If you click on the image you can see the full image, which also includes several canyons oriented in what seem to be random directions.

I first heard this geological term for regions on Mars shortly after the first orbital missions circling Mars began taking images back in the 1970s. It applied to places where the terrain was hummocky, a crazy collection of hills forming no pattern at all. Earth does not really have such terrain.

The close-up to the right also shows that at least one of these hills is fractured, made up of several large pieces that have separated over time.

This image was part of the May 2nd image release from the high resolution camera on Mars Reconnaissance Orbiter. What makes it interesting is its location on Mars. The image below shows that location, indicated by a white cross.
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Volcano or Impact?

Elliptical crater with flow features

Cool image time! Yesterday the Mars Reconnaissance Orbiter (MRO) team released its monthly image dump of more than 500 new photographs, taken by the spacecraft’s high resolution camera. As I have started to do in the past few months, I am reviewing this collection and plan to post a few of the more interesting images over the next month. On the right is the first of this series. I have cropped and reduced the resolution to show here, but you can see the full resolution version if you click on the image.

The MRO team labels this image an “elliptical crater with flow features.” The first impression one gets from the image is that the impact that caused the crater came from the side and hit the ground obliquely, creating the crater’s oval shape and the lava-type flow features in the crater’s floor.

As is almost always the case with Martian geology, beware of first impressions. You need to give any feature both a more detailed look as well as a broader view to have any chance at understanding its context and geology.
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Imaging restrictions on Mars Reconnaissance Orbiter

Young lava flows on Mars

In releasing a new set of four captioned images today from the high resolution camera on Mars Reconnaissance Orbiter (MRO), the captions from each also included this paragraph:

Note: HiRISE has not been allowed to acquire off-nadir targeted observations for a couple of months due to MRO spacecraft issues, so many high-priority science objectives are on hold. What can be usefully accomplished in nadir mode is sampling of various terrains. Especially interesting in this observation are bedrock exposures, which provide information about the geologic history of Mars. “Nadir” refers to pointing straight down.

The image restrictions are probably related to either or both the battery and and reaction wheel issues noted in recent status report. What it means is that though they can still take good and revealing images, like the one to the right, cropped and reduced to post here, showing very young lava flows only a few million years old, scientists have less flexibility in what they can photograph.

If you click on the image you can see the full resolution version. The reason scientists think these are young flows is that they are so few craters here. The lava flows are located in the southern lava flows coming off the large volcano Elysium Mons, which sits due west of Mars’ largest volcano, Olympus Mons. These flows are also in the transition zone between Mars’ low flat northern plains and its high rough southern terrain.

When and if the spacecraft can resume full imaging operations is unknown. Based on the status report, it might never do so.

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Status update on Mars Reconnaissance Orbiter

Link here. The story is focused on the decision by NASA to hold off launching a replacement for MRO and instead keep it operating for another decade. In telling this story, however, the article also provides us a detail look at the spacecraft’s present condition.

[A]ging batteries and gyroscopes, used to store electricity and aid navigation, will have to be carefully watched in the coming years to keep the mission going. “We found that they weren’t charging at full capacity,” Tamppari said of the batteries. MRO charges its batteries through its solar arrays while in sunlight. During night passes over Mars, the orbiter draws electricity from its batteries for about 40 minutes during each two-hour lap around the planet. The spacecraft now charges its batteries higher than before, NASA said, and engineers sent up commands for MRO to reduce the draw on the batteries while in shadow.

MRO’s two inertial measurement units are also showing signs of their age. Each redundant unit contains three gyroscopes and three accelerometers, feeding data about the spacecraft’s orientation to on-board computers. One measurement unit likely in the final months of its useful lifetime, Tamppari said, and the other is showing signs of degradation.

Ground controllers found a work-around by implementing an “all-stellar” navigation mode on MRO in March. The new technique allows the orbiter to sense the positions of the stars to determine which way it is pointing. “In all-stellar mode, we can do normal science and normal relay,” said Dan Johnston, MRO project manager at JPL, in a statement released in February. “The inertial measurement unit powers back on only when it’s needed, such as during safe mode, orbital trim maneuvers, or communications coverage during critical events around a Mars landing.”

There’s more at the link. Since MRO is also used as the main communications relay satellite between the Martian ground-based probes and the Earth, the story also outlines the communications capabilities of all spacecraft presently orbiting Mars. All told, it seems that if MRO fails the research on the surface will be significantly impacted, even if the rovers and landers are all still working.

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Near the Martian shoreline

One of the prime areas of research for Mars planetary geologists is the region on Mars where the geography appears to transition from the southern cratered, rough terrain to the northern low, generally smooth, and flat plains. It is theorized by some scientists that the northern plains were once an ocean, probably shallow and probably intermittent, but wet nonetheless for considerable periods. The global map of Mars below, created by the laser altimeter on Mars Global Surveyor, clearly shows the obvious elevation differences between the low northern plans (blue) and the high, more cratered southern regions (changing from yellow to orange as you move higher).

Labeled global Map of Mars

Scientists have spent a considerable effort studying this transition zone (green on the map), illustrated by just one example I recently highlighted, showing that, though there does not appear to be a clear shoreline in many places, there is strong evidence that a shallow ocean repeatedly rose and fell in this transition zone, leaving behind geological ripple marks vaguely reminiscent of those seen on a beach caused by the rise and fall of the tides.

Today we highlight another example, taken in January 2018 at the location indicated by the cross on the above map.
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Martian craters go splat!

Overview of the volcanic Tharsis Bulge on Mars

Cool image time! In continuing my exploration of this month’s Mars Reconnaissance Orbiter (MRO) image release, I found two interesting images of small craters, one as part of that image release, the other found completely by accident.

The map on the right, taken from the MRO HiRISE archive page, shows the locations of these two images. Both are located in the lava plains that surround the giant volcano Pavonis Mons, the central volcano of the three volcanoes to the east of Olympus Mons. Previously, I have done posts focusing specifically on both Pavonis Mons and Arsia Mons. Not only is the geology of these gigantic volcanoes fascinating, there is evidence that ancient glacial ice lurks in lava tubes on their slopes, making them potentially prime real estate for future explorers.

The first image, labeled #1 on the image above, was taken in January 2018 to get a better look at a small crater on the surrounding lava plains, and was part of the MRO March image release. I have cropped it to post here, focusing on the crater itself.

My first reaction on seeing the image was, “Did this impact not go splat when it hit?”
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More weird Mars geology

Low resolution of full image of crater

Cool image time! Yesterday the Mars Reconnaissance Orbiter team released 460 images taken by the spacecraft’s high resolution camera, HiRISE, as part of their normal and routine image release program. Obsessed with space exploration as I am, I like to scan through these new images to see if there is anything interesting hidden there that will show up eventually in a press release. For example, the first image in this release is a look at Vera Rubin Ridge and Curiosity. I would not be surprised if there is a press release soon using this image, probably aimed at outlining the rover’s future route up Mount Sharp. (The present overview traverse map is getting out of date.)

Sometimes however I find images that might never get a press release but probably deserve it. The image on the right, reduced in resolution to show here, is one such example. It is a strip taken from rim to rim across an unnamed crater located in the mid-northern latitudes of Mars, west of Olympus Mons. A review of past images by other Mars orbiters/probes suggests that no good high resolution image of this crater had ever been taken before.

If you click on the image on the right, or go to the actual image site, you can see the original in full resolution. It is definitely worthwhile doing this, because the strip shows some strange and inexplicable geology on the floor of the crater as well in its confusing central peak region. Numerous features appear to have been exposed by later erosion. The many small craters for example are I think what planetary geologists call pedestal craters. The surrounding terrain is less erosion-resistant, so as that terrain erodes away it leaves the crater behind, with its floor actually sitting higher than the surrounding flats.

What makes these craters even weirder however is that their rims appear to have eroded away even more than the surrounding terrain, so that all of these small craters (assuming that is what they are) have ringlike depressions surrounding a circular platform.

In the crater’s central peak region the terrain is even more strange. Sticking up out of the ground are some arched short ridgelines, which appear to have been exposed by erosion. That peak area however also has many strange flow features that I find completely baffling. It almost appears to me that as the molten peak area started to solidify after impact, someone went in with a stirring spoon and did some mixing!

The map below the fold provides the location context for this crater, with the crater’s location indicated by the arrow.
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Mars Reconnaissance Orbiter comes out of safe mode

On February 23 the Mars Reconnaissance Orbiter (MRO) engineering team was able to bring the spacecraft out of safe mode, after a low battery voltage reading caused it to shut down.

Mission team members brought MRO out of safe mode on Friday (Feb. 23), NASA officials said. The orbiter seems to be in good health overall; the battery voltage is back to normal, MRO is communicating with Earth, and temperatures and power levels are stable, agency officials said.

But MRO’s handlers haven’t put the orbiter back to work yet. “We’re in the diagnostic stage, to better understand the behavior of the batteries and ways to give ourselves more options for managing them in the future,” MRO project manager Dan Johnston, of NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “We will restore MRO’s service as a relay for other missions as soon as we can do so with confidence in spacecraft safety — likely in about one week. After that, we will resume science observations.”

Overall this sounds like very good news.

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Mars Reconnaissance Orbiter in safe mode

After detecting low battery voltage, Mars Reconnaissance Orbiter (MRO) went into safe mode on February 15.

The orbiter is solar-powered but relies on a pair of nickel-hydrogen batteries during periods when it is in the shadow of Mars for a portion of each orbit. The two are used together, maintaining almost identical charge during normal operations.

The spacecraft remains in communication with Earth and has been maintaining safe, stable temperatures and power, but has suspended its science observations and its service as a communications relay for Mars rovers. Normal voltage has been restored, and the spacecraft is being monitored continuously until the troubleshooting is complete.

It appears that all is under control. If MRO goes down, however it will a big loss for Mars research, as the spacecraft not only produces the highest resolution images of the ground, it also acts as one of several communications satellites between the Earth and the rovers on Mars. With two rovers there now, and at least two more planned for arrival in 2020, the loss of this communications link would be crippling.

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Massive flow on Mars

Massive flow on Mars

Cool image time! The image on the right, cropped to post here, comes from a Mars Reconnaissance Orbiter image that shows a massive relatively recent and dark slope streak that emanates out from a single point on the surface. (Note that the release at this link rotates the image so that north points down. I have rotated back so that north points up.)

Streaks form on slopes when dust cascades downhill. The dark streak is an area of less dust compared to the brighter and reddish surroundings. What triggers these avalanches is not known, but might be related to sudden warming of the surface.

These streaks are often diverted by the terrain they flow down. This one has split into many smaller streaks where it encountered minor obstacles. These streaks fade away over decades as more dust slowly settles out of the Martian sky.

Point of origin for flow

Location of flow, west of Olympus Mons

The MRO release focuses on the fingerlike breakup of the flow as it descends into sand-dune filled plain. What is more interesting to me is the terrain where this flow originated. A close-up of that area from the full image, shown on the right, reveals a feature that could be a wash running in line with the flow’s origin, and leading uphill to a dark feature that is a likely a cliff face. (The light in this image is coming from the southeast.)

This location, at 15.2N latitude, 214.9E longitude and shown by the small cross in the image on the right and captured from this page, is west of Olympus Mons, the largest volcano on Mars. This suggests to me that the originating feature might be an outlet from a lava tube, from which water suddenly seeped out to produce this massive slope streak. A look at the mesa from which this flow came, cropped from the full image and posted below the fold, shows numerous similar slope streaks of varying ages flowing out of this mesa, with some very faint because they occurred farther in the past. Some are even within the bowl at the top of the mesa.

Whether these come from lava tubes is definitely unclear, and I suspect I will be told by geologists not likely. The seeps however do suggest strongly that this mesa might be a very good location for future colonists to look for underground water ice. Since clouds form on the western slopes of Arsia Mons, the southernmost of the three giant volcanoes to the east of Olympus Mons, and that past glacial activity has been documented there, I wonder if some of these same conditions might also exist here, on the nearby terrain west of Olympus Mons.
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A good health check for Mars Reconnaissance Orbiter

Link here. The article outlines in good detail the spacecraft’s present condition, which is excellent despite being in space since 2005, as well as outlining the measures being taken to keep it operational into the 2020s.

This item is probably the biggest cause for concern:

For example, some HiRISE images taken in 2017 and early 2018 show slight blurring not seen earlier in the mission. The cause is under investigation. The percentage of full-resolution images with blurring peaked at 70 percent last October, at about the time when Mars was at the point in its orbit farthest from the Sun. The percentage has since declined to less than 20 percent. Even before the first blurred images were seen, observations with HiRISE commonly used a technique that covers more ground area at half the resolution. This still provides higher resolution than any other camera orbiting Mars — about 2 feet (60 centimeters) per pixel — and little blurring has appeared in the resulting images.

HiRISE is the spacecraft’s primary instrument, and its most valuable. If it goes, we will lose our best tool right now for looking in detail at the Martian surface.

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Weird Martian geology: Kaiser Crater

Kaiser Crater bedrock

Cool image time! This week JPL’s image site highlighted a picture taken by Mars Odyssey of the floor and dunes inside Kaiser Crater, located to the west of Helles basin in an area dubbed the Noachis Region.

To my eye, the Mars Odyssey picture was interesting, but not worth a post here on Behind the Black. However, I decided to take a look at what HiRise, the high resolution camera of Mars Reconnaissance Orbiter (MRO), had taken of the same area, just out of curiosity. A search at the master HiRise image site at the same latitude and longitude (-45 latitude, 180 longitude) showed that HiRise had imaged a part of the same area, but at much higher resolution.

When I zoomed in on this hi resolution image I came across some interesting and weird geology, cropped to show here on the right. Now this, I thought, is worth posting. Notice how the dark tracks, caused by dust devils, leave no tracks as they cut across the brighter areas. Obviously, these bright areas have no dust or sand, and are likely solid bedrock of some kind. The depressions might be craters, but they also might not. The raised area around the depressions might have been caused by the impact, or it might have been caused by some internal geological process that caused the depression while also raising the surrounding bulge. Since then the wind has been steadily depositing sand in the depressions, causing it to get trapped there.

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The mysterious dark splotches of Mars

The dark splotches of Mars

Cool image time! The image on the right, cropped and reduced in resolution to post here, shows one particular dark splotch in a region with several similar dark areas.

Geologists aren’t quite sure what to make of the dark splotch in the middle of this image, one of several similar dark splotches that extend east and west for over 100 kilometers. From measurements made in infrared, this and other dark splotches have what we call “high thermal inertia,” meaning that it heats up and cools down slowly. Scientists use thermal inertia to assess how rocky, sandy, or dusty a place is. A higher thermal inertia than the surrounding area means it’s less dusty.

The image below the fold shows at full resolution the area indicated by the white box. It provides me no clue as to the cause for the darker color. I think we can speculate all we want, but the truth is that we simply don’t have enough information. We need a closer look, including boots on the ground, to figure this out.
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Mars or a bacterial cell?

Mars's southern polar regions

Cool image time! The image on the right, reduced and cropped to show here, was taken by Mars Reconnaissance Orbiter and shows just one spot in Mars’s southern polar regions. The surface only looks like bacteria because the basic structure of both is based on fractals. Scientists call this area “swiss-cheese terrain” because of the many holes that have opened up there.

The texture is very alien, bearing more of a resemblance to the universe of the very small, rather than the universe far, far away. But if this is a polar cap, then why does it not look like the polar caps on Earth? Indeed, there is no equivalent terrain observed here on Earth.

The so-called “Swiss cheese terrain,” referencing the numerous holes of the region, is a product of seasonal exchange between the surface and the Martian atmosphere. With a predominantly carbon dioxide content at 98 percent, the colder temperatures condense the gas out of the atmosphere to produce dry ice. The prevalence of water is more concentrated in the north, leaving the South polar region more carbon dioxide rich, and it’s this difference in composition that generates the unusual texture of the Swiss cheese terrain.

Be sure and take a look at the full resolution image. It is quite wild.

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A Martian Journey

The exploration of the solar system has barely begun. Though we regularly get to see some spectacular images taken by the fleet of unmanned planetary probes that now circle or rove the various planets throughout the solar system, we mustn’t think we have seen very much. In truth, we have only gotten a very distant glimpse of only a few tiny spots, most of which have been viewed from very far away. Even at the highest resolution the images do not really tell us what it really will be like when we can stroll across those surfaces routinely.

To give you an idea of how much remains hidden, let’s take a journey inward from Mars orbit. The image below looks down on a good portion of the Martian globe, with the giant volcano Olympus Mons on the left, its three companion volcanoes in line to the east, and the vast valley of Valles Marineris east of these. This valley would cover the continental United States almost entirely, and extend significantly beyond into the oceans on either side.

Olympus Mons and Valles Marineris

This was essentially our first good look at Mars, taken from orbit by Mariner 9 in 1971.
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