Tag: geology

Ingenuity’s images from 16th flight on November 21st

11:18 am

Ingenuity color image from 16th flight
Click for full image.

Cool image time! The photo to the right, reduced and enhanced to post here, was the first color image taken by Ingenuity during its 16th flight on Mars on November 21st. The picture was taken about fifteen seconds after take-off, and I think looks west toward the rim of Jezero Crater in the distance.

The flight itself was relatively short, essentially a quick hop about 380 feet to the north to land at the edge of the rough area dubbed Seitah. The team is going to slowly take the helicopter back to its initial landing field, Wright field, over several hops. This was the first.

If you want to peruse all 113 images from the flight, go here and set the sol range from 268 (November 20) to 274 (November 26). That will show all 113 images taken during the November 21st flight.

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Sculptured lava south of Olympus Mons?

10:51 am

Sculptured lava?
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Time for a cool image! The photo to the right, rotated, cropped, and reduced to post here, was taken on September 8, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a region of strangely sculptured terrain located several hundred miles south of Olympus Mons.

It appears the prevailing winds are to the west. The question is whether the wind is shaping a hard lava surface, over eons, or is shaping instead layers of dust or volcanic ash quickly and seasonally. At this location either is possible. In fact, we might even be seeing evidence of both at the same time.

The overview map below shows that the location is just outside the Medusae Fossae Formation, the largest volcanic ash deposit on Mars.
» Read more

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Volcanic vent on Mars

2:43 pm

Overview of Arsia Mons pits

To understand today’s cool image we really should start from a distance and zoom in. The overview map to the right focuses in on the two southernmost giant volcanoes in the string of three that sit to the east of Mars’ biggest volcano, Olympus Mons, and to the west of the planet’s biggest canyon, Valles Marineris.

The black dots mark the locations of the many high resolution photos taken by Mars Reconnaissance Orbiter that I have featured previously on Behind the Black. Many are isolated openings with no related geological features. Others appear to be skylights into a more extensive lava tube, hinted at by either a continuing surface depression or a series of similar skylights.

The white dot marks the location of today’s cool image, about 350 miles south of Arsia Mons’ caldera.
» Read more

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UAE Al-Amal Mars orbiter finds surprising variations in Mars atmosphere

10:32 am

Oxygen variations in Martian atmosphere
Click for full graphic.

The United Arab Emirates Al-Amal (“hope” in English) Mars orbiter has discovered unexpected variations of oxygen and carbon monoxide in the Martian atmosphere.

The EMM team had expected to observe a relatively uniform emission from oxygen at 130.4 nm across the planet and yet here we are, faced with unpredicted variations of 50% or more in the brightness.

The image to the right, cropped and reduced to post here, shows the variations in oxygen on Mars’s dayside. Though the map does not indicate the geography below, the concentration of oxygen in the northern latitudes appears to correspond to the planet’s northern lowland plains. In fact, the variations should not have been a surprise, since the surface of Mars has such a stark dichotomy between its northern and southern hemispheres.

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Craters in the soft Martian northern lowland plains

12:25 pm

Craters in the soft Martian northern lowland plains
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Cool image time! The photo to the right, cropped and reduced to post here, was a featured image today from the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The caption, written by Carol Weitz of the Planetary Science Institute in Arizona, focused on the wind patterns created within these craters.

These impact craters in the northern middle latitudes have interesting interiors: all of them have wind-blown (aeolian) ripples.

Outside of the craters and along the crater floors, the ripples are all oriented in the same direction. However, along the walls of some of the larger craters, the ripples are situated radially away from the center, indicating the winds moving inside the larger craters can be influenced by the topography of the crater wall.

Additionally, many of the larger craters have layered mesas along their floors that are likely sedimentary deposits laid down after the craters formed but prior to the development of the aeolian ripples.

I am further intrigued by the rimless nature of these craters, as well as the lack of significant rocky debris at their edges. They all look like the bolides that created them impacted into a relatively soft surface that, rather than break up into rocks and boulders, melted, flowed, and then quickly refroze into these depressions.

The location, as always, provides us a possible explanation.
» Read more

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Zhurong’s continuing travels on Mars

10:26 am

Zhurong overview map
Click for original map.

This past week the Chinese press released a new but limited update on the status of both its Mars orbiter Tianwen-1 and its Mars rover Zhurong.

The map to the right uses as its background a high resolution picture from Mars Reconnaissance Orbiter. I have superimposed Zhurong’s route in green. You can get an idea of how far the rover has traveled since resuming communications with Earth in late October by comparing this map with the one I posted then. After stopping at a small sand dune (the crescent-shaped white features), it curved around to head to the southeast towards a rough area and a trough that is thought to be filled with sediment.

Meanwhile, the orbiter has shifted its orbit, changing from one dedicated mainly as providing a communications relay between Zhurong and Earth to one that now allows it to begin a two-year photographic survey of Mars.

To supplement the resulting gaps in communications for Zhurong, China and the European Space Agency (ESA) have made their first test using ESA’s Mars Express satellite as a relay satellite. Both hope to know soon whether it worked.

In either case, Zhurong’s travels will likely be slowed somewhat due to the reduction in communications access.

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Snow on Martian dunes

12:58 pm

Snowy dunes near the Martian north pole
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Close-up of snowy dunes
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Cool image time! The first photo to the right, rotated, cropped, and reduced to post here, was taken on September 19, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows what appears to be snow nestled in the hollows of many dunes.

The second photo, cropped to post here, shows in high resolution the area in the white box.

Is that snow water, or dry ice? The location is very far north, 76 degrees latitude, so it could be either. Since the photo was requested by Candice Hansen of the Planetary Science Institute in Arizona, I emailed her to ask. Her answer:

Early in the spring all the bright stuff is dry ice. As it gets later in the spring it is probably still mostly dry ice but with HiRISE images alone we cannot really distinguish the composition of the ice. In-between the dunes it is almost certainly bare ground late in the spring, but since the dunes are dark the surface just looks bright in contrast

This picture was taken in summer, which suggests the snow is probably water, not dry ice. Yet, all the snow is found in the north-facing hollows, places that will remain mostly in shadow at this high latitude, 76 degrees north. Thus, it is possible that the snow is the last remaining traces of the thin dry ice mantle that covers the Martian poles down to about 60 degrees latitude during the winter, and sublimates away in summer.

Hansen had requested a whole bunch of similar images of such snowy dunes. As she explained,
» Read more

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Scientists: Asteroid in an orbit entwined with the Earth might be Moon rock

11:45 am

Data obtained by scientists using ground-based telescopes now suggests that the small asteroid Kamo`oalewa, which has an orbit that makes it a quasi-Moon of the Earth, might have originally come from the Moon.

From their paper’s abstract:

We find that (469219) Kamoʻoalewa rotates with a period of 28.3 (+1.8/−1.3) minutes and displays a reddened reflectance spectrum from 0.4–2.2 microns. This spectrum is indicative of a silicate-based composition, but with reddening beyond what is typically seen amongst asteroids in the inner solar system. We compare the spectrum to those of several material analogs and conclude that the best match is with lunar-like silicates. This interpretation implies extensive space weathering and raises the prospect that Kamo’oalewa could comprise lunar material.

Kam’oalewa — which is only about 150 feet across — is one of five such quasi-Earth-moons. All orbit the Sun in orbits that are similar to the Earth’s and are such that the asteroids periodically loop around our planet each year.

This data will be useful to the Chinese, who are planning a mission to Kamo-oalewa in ’24 to grab samples.

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A volcanic extrusion on the floor of Valles Marineris?

2:52 pm

A volcanic extrusion on the floor of Valles Marineris?
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on August 31, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels a “possible contact between two units.”

I think that contact is the point where that eroded mountain touches the surrounding smooth canyon floor. The mountain itself looks to me to be a very eroded extrusion of lava that was placed there from below a very very long time ago, covered later by material, and now exposed for a long enough period that its surface appears to have been carved by wind and even possibly flowing water or ice.

Because it is lava it is more resistant to erosion, which is why it sits higher than the smooth terrain around it. Even though both experienced the same processes of wear over time, the mountain’s surface was only carved away partly, while the material that had been in the floor was washed away entirely.

This is all a guess. However, a look below at the overview map, showing this mountain’s location on Mars, as well as MRO’s wider view from its context camera, I think strengthens my hypothesis.
» Read more

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Frozen lake bed in the Martian high latitudes?

2:03 pm

Frozen lakebed in the Martian high latitudes?
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Today’s cool image comes from today’s Mars Reconnaissance Orbiter’s (MRO) high resolution picture of the day, rotated and cropped to post here. The original was taken back on March 28, 2017.

What formed those strange circular ridges and the many small cracks and hollows? The caption provided is somewhat vague and I think confusing:

This formation looks like a crater from a meteor impact rather than an ancient caldera of a volcano. Connected to the crater is a carved-out area that resembles a lake bed. At high resolution, we might be able to determine the likelihood of a water lake bed or lava bed. This observation will give insight into some of the interesting geology of this area.

The crater this caption is referring to is not visible in the image provided. It can be seen to the west of this location, in the MRO context camera picture below.
» Read more

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Curiosity: Approaching the saddle

9:21 am

The saddle ahead
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Cool image time! The photo to the right, reduced to post here, was taken on November 5, 2021 by Curiosity’s high resolution camera, and looks forward at its planned route up onto the saddle ahead, where the rover will turn right and climb up into Maria Gordon Notch. (See this October post for a map outlining the rover’s future travels.) I think that cliff face is between 40 to 60 feet high, though this is a very wild guess.

As noted by Abigail Fraeman of JPL on the Curiosity blog on November 3, 2021,

The terrain is beginning to steepen as Curiosity gets close to the end of this region, so even though we’re only a few drives away from our last drill site … we’ve already climbed 25 m higher!

The route ahead looks equally steep, though the ground actually appears less rough, with fewer large jagged boulders that Curiosity must avoid to protect its wheels.

It will likely be at least one to three weeks however before Curiosity gets to that saddle. The science team has begun a drilling campaign at the present location, and this will take time, depending on how many holes they decide to drill.

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Ingenuity next flight will begin route retracing its path

9:20 am

Overview map

The Ingenuity engineering team has revealed that the helicopter’s 15th flight on Mars will have it begin retracing its steps, following approximately the same flight route as it heads back towards Perseverance’s landing site in Jezero Crater.

Flight #15 is the start of our journey back to Wright Brothers Field [the helicopter’s initial flight test area just north of the landing site]. Taking place no earlier than Saturday, Nov. 6 at 9:22 a.m. PT, or 12:03 LMST (local Mars time), the 254th sol (Martian day) of the Perseverance mission, Flight #15 will return Ingenuity back to the Raised Ridges region, imaged in Flight #10. In this flight the helicopter will traverse 1,332 feet (406 meters) during 130 seconds of flight, travelling at 11.1 mph (5 mps) groundspeed. We’ll capture color return-to-earth (RTE) high resolution (13MP) images, one post-takeoff pointed to the SW, and nine pointed toward the NW along the flight-path. Nominal altitude for the flight is expected to be 39.3 feet (12 meters) above ground level.

This will be the second flight of Ingenuity during Mars’ summer low air-density, requiring that the rotor blades are spun at 2,700 RPM to compensate. This flight will generate critical high-RPM motor performance, which the team will use to design and tailor upcoming low-density flights in the months ahead.

Perseverance is presently sitting in an area they have dubbed Seitah, a region the rover skirted around to get to this point. I had hoped both the helicopter and rover would return to the north cutting across Seitah and thus scout out new terrain. Instead, it appears that both the rover and helicopter will return as initially planned, traveling over the same ground both took to get where they are today.

In other words, the teams have decided to take the safest route, though it will provide them much less new science data. While this might seem prudent, it really appears overly cautious, based on the capabilities of Perseverance and the roughness of the terrain in Seitah. Curiosity is presently traveling across far more difficult terrain in the mountains at the foot of Mt Sharp, and it is doing so with wheels that are damaged and not as well designed as Perseverance’s. Not roving in uncharted terrain seems a waste of Perseverance’s capabilities.

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The strange surface of Mars’ north pole icecap

1:02 pm

Mars' north pole icecap
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Cool image time! The photo to the right, rotated, cropped, and annotated to post here, was taken on September 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows us a very small section of Mars’ north pole icecap.

What are we looking at? The picture was taken in summer, so by this point the thin mantle of dry ice that falls as snow in the winter and covers the north pole down to about 60 degrees latitude has sublimated away. This surface thus is water ice interspersed with Martian dust.

Yet, unlike the Antarctic icecap on Earth, the ice surface is not smooth and flat. Instead, this Martian ice has a surface that is a complex arrangement of hollows and ridges, all about the same size. Why?

And what are the two larger white spots? What caused them and why are they the only differently-sized objects in the picture?

The full resolution close-up, found at the image website, provides some answers to these questions.
» Read more

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Landing site chosen for Intuitive Machines Nova-C lunar lander

11:57 pm

NASA scientists have now chosen the landing site for the privately built Nova-C lunar lander, built and designed by Intuitive Machines, that late next year will carry three science instruments to a ridge close to Shackleton Crater near the Moon’s south pole.

NASA data from spacecraft orbiting the Moon indicate this location, referred to as the “Shackleton connecting ridge,” could have ice below the surface. The area receives sufficient sunlight to power a lander for roughly a 10-day mission, while also providing a clear line of sight to Earth for constant communications. It also is close to a small crater, which is ideal for a robotic excursion.

These conditions offer the best chance of success for the three technology demonstrations aboard. This includes the NASA-funded Polar Resources Ice-Mining Experiment-1 (PRIME-1) – which consists of a drill paired with a mass spectrometer – a 4G/LTE communications network developed by Nokia of America Corporation, and Micro-Nova, a deployable hopper robot developed by Intuitive Machines.

One of the goals of the mission is to drill down three feet to see if ice can be detected. Another is to simply test this engineering to better refine it for the many other unmanned lunar missions that will follow in the next few years.

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Two skylights into connected Martian lava tube?

3:33 pm

Two skylights into a connected Martian lava tube?
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Cool image time! The photo to the right, cropped and annotated to post here, was taken on September 1, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have annotated it to note the two apparent skylights that appear aligned along a north-south depression.

The grade is downhill to the north. If you look at the full image you will see that this north-south depression extends for a considerable distance beyond the edges of the cropped image above, with that depression appearing to dissipate to the north into a series of parallel very shallow depressions, almost like the lava had flowed out of the tube and formed branching surface rivulets heading south.

The overview map shows that this tube is on the northern flanks of the volcano Arsia Mons.
» Read more

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Curiosity looks back across the alien landscape of Mars

12:45 pm

Gale Crater, October 31, 2021
Click for image.

Cool image time! The photo above, the first of 21 identical images taken by Curiosity’s right navigation camera, taken at intervals of about thirteen seconds on October 31st, was probably snapped as part of an effort to spot a moving dust devil. At the resolution available to my software, I see nothing when I compare all 21 photos.

What I do see is a remarkably alien landscape. In the distance can be seen the mountains that mark the rim of Gale Crater, 30-plus miles away. On the image’s right edge you can see the rising slope heading up to the peak of Mount Sharp about 13,000 feet higher.

In the center are those blobby mesas that make this terrain look so strange. For the past decade Curiosity has been traveling from the floor of the crater on the picture’s far left to circle around that dark sand dune sea to climb up the mountain slopes in the foreground in front of those mesas.

It is now heading to the right, into the mountains that make up Mount Sharp. Such a view of the floor of Gale Crater will thus be for the next few years more difficult to catch, as the mountains themselves will block the view. Assuming the rover survives long enough, it will have to climb much higher before it can get such an expansive view again.

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Holes in snowy ice on Mars?

1:30 pm

Holes in snowy ice on Mars?
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Cool image time! Today we return to the regions surrounding Milankovic Crater in the high northern latitudes of Mars. The photo to the right, cropped and reduced to post here, was taken on June 1, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a spray of impact craters where the bolides apparently landed in relatively soft material. The location itself is about 10 miles to the southeast of the 74-mile-wide crater, and sits within its rim ejecta blanket.

The label for the image says this is showing “crater modification,” which suggests that the rimless nature of these craters became so after their creation. This location, at 54 north latitude, is in a region of Mars where scientists have found a lot of evidence of near surface ice. For example, within Mikankovic Crater itself they have identified numerous scarps with clearly seen pure ice layers.

If ice is close to the surface here, then the ground could be like soft snow on Earth, especially because Mars’ lighter gravity would not compress that ice as much. Think about what happens when you toss pebbles into soft snow. They fall through, and leave behind holes not unlike the ones we see in this picture. Later, sunlight would begin to modify the holes so that their edges grow outward, once again exactly as we see here.

The overview map below as always gives some context, which in this case has less to do with Mars but with Elon Musk and Starship.
» Read more

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Solid dry ice in Moon’s permanently shadowed craters?

10:30 pm

Stable dry ice at Moon's south pole
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Using eleven years of data from Lunar Reconnaissance Orbiter (LRO), scientists think they have identified small areas in the Moon’s permanently shadowed interiors of some polar craters where the temperatures are always cold enough for dry ice (solid carbon dioxide) to be stable.

The map to the right, cropped and reduced to post here, is Figure 2 of the paper. It shows the areas at the south pole where stable dry ice is thought possible. The darker blue/purple are colder and thus are expected to have less sublimation. From the abstract:

Carbon-bearing species would be essential for sustained robotic or human presence on the Moon, for use in rocket fuel and biological materials. Various volatiles can be cold-trapped in permanently shadowed craters near the lunar poles. The existence of carbon dioxide cold traps has previously been surmised, but the required temperatures are near the lowest surface temperatures that have been reliably measured. Extensive and improved analysis of 11 years of orbital surface temperature measurements establishes the existence of carbon dioxide cold traps on the Moon, which potentially host high concentrations of solid carbon dioxide. Large CO2 cold traps are rare, however, and the geographic concentration of the resource will have policy implications. [emphasis mine]

The paper also adds in its conclusion that these regions are likely going to be of high value, and will thus likely be prime settlement and mining targets by everyone. As they note, “That this resource is highly concentrated geographically has implications for the governance of the lunar surface.”

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One last look at a Martian mountaintop

9:14 am

Siccar Point
For the original images go here and here.

The image above is a mosaic made from two Curiosity navigation photos taken on October 23, 2021 and combined, cropped, and reduced to post here. It shows the top 30 feet or so of Siccar Point, the spectacular outcrop that I have featured several times previously.

Curiosity has now traveled past this outcrop, so that this view above is no longer visible to the rover. I post it now as a farewell image of what I think is the most breath-taking feature yet seen by any planetary lander — manned or unmanned — since the first set down on the Moon in the mid-1960s. It also illustrates with great clarity the alien nature of Mars. Those delicate overhanging rocks would not be possible on Earth, with a gravity about two and a half times heavier than Mars.

Note too that I have not enhanced the contrast or brightness. I think the twilight light here actually gives us a sense of the real brightness of a clear Martian day. Because the Sun is much farther away, even at high noon it provides much less illumination than on Earth. A bright day on Mars to our Earth-adapted eyes will always feel like dusk.

Meanwhile the science team is quickly pushing the rover south, to get…

…closer to the area we are targeting for our next drill campaign. This drive should leave us with bedrock in the workspace for additional contact science on the weekend. This terrain continues to be very challenging, with large boulders, sharp rocks that are wheel hazards, and sand ripples, like the terrain shown in the image. These drives take a while to plan to make sure we are avoiding all the hazards while getting to where science wants to go. Our paths end up looking a little “drunk” as we weave our way around obstacles.

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Curiosity marches on into the mountains

1:09 pm

Curiosity marches onward to Maria Gordon Notch
Click for full image.

Overview map
Click for interactive map

With the end of the solar conjunction in the first half of October, blocking communications with Mars because the Sun was in the way, Curiosity has resumed its travels. It has moved past the spectacular outcrop I have highlighted previously, an outcrop the science team has labeled Siccar Point.

They are now moving south at the base of the cliff to the west, the top of which is a plateau they call the Greenheugh Pediment, heading for a gap where the rover will be able to turn right and head up onto that pediment. The red dotted line on the overview map to the right shows this route, which corresponds to the red dotted line on the photo above.

I estimate the cliffs on both sides of Maria Gordon Notch are about 100 feet high. The notch itself I estimate is about 750 feet away. At the pace Curiosity has been traveling across this rough ground, it could probably reach it in about two to three weeks. However, I expect the science team will stop at least once along the way to do more detailed science work, so that journey might take a month or slightly more.

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China resumes communications with Zhurong Mars rover

10:13 am

Elevation map of Zhurong location
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The new colonial movement: China yesterday announced that it has regained communications with its Zhurong rover, located in the Martian northern lowland plains of Utopia Planitia.

The image to the right, cropped and annotated by me to post here, is a digital terrain map created from two high resolution photos taken by Mars Reconnaissance Orbiter (MRO). The black line shows the route Zhurong has traveled since landing in May.

According to [Chen Baichao, the chief designer of Zhurong], the rover has traveled more than 1,000 meters since it landed on Mars at the southern part of Utopia Planitia in May 2021. After the solar conjunction, it will head south to find mud volcanoes, which scientists are interested in, located about 10 km away.

American scientists had hoped Zhurong would head north to a much larger mud cone that was much closer. Their decision to head south to the smaller cones farther away tells us that they have given themselves a much more challenging mission. It also suggests they decided it will be easier to get Zhurong closer to a smaller cone.

Based on that 10 kilometer distance, it seems the Chinese are aiming for the cones near the bottom of the map. It took Zhurong three months to travel the distance shown. At that pace, to get to those small southern mud cones will likely take, at a minimum, about fifteen months. Though the ground is quite flat, the rover will either have to negotiate one small rise of about 15 feet, or detour to the east somewhat to find a less steep route.

It is also possible that they will instead head to the mud cone south of the large impact crater. It is also a small cone, is much nearer, and will not require them to get past that rise.

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Layered glaciers in Mars’ glacier country

3:48 pm

Layered glacier in Mars' glacier country
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Cool image time. The photo to the right, cropped and reduced to post here, was taken on August 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows two different impact craters in a glacial region dubbed Nilosyrtis Mensae, located in the northern mid-latitudes in the 2,000 mile long strip chaos terrain that I have labeled glacier country because practically every image finds them there.

The splash apron surrounding the larger crater is typical of craters in Martian regions where ice is thought to be near the surface.

What makes this picture interesting is that the glaciers appear layered. You can see evidence of this in the mounds inside both craters. Those mounds appear to represent earlier periods when there was more ice here. Since then the mounds have partly sublimated away.

You can also see evidence of layers in the material surrounding the nearby larger mounds.

The map below shows us where this image is, relative to all of glacier country as well as the rover Perseverance in Jezero Crater.
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Curiosity’s new mountain views

1:14 pm

Curiosity's future route
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With the resumption of communications with Mars, following the two week hiatus because the Sun was in the way, Curiosity is about to begin its travels again. The view above, taken by the right navigation camera and reduced and annotated to post here, looks forward, with the red dotted line indicating the planned route.

The distinct white outcrop on the right top is the same spectacular outcrop I have highlighted previously.

At the moment however the rover is not going anywhere. Just before the hiatus the scientists had Curiosity move a short distance to crush some nearby nodules so that they could see their interior. At their update they post an image of one crushed nodule, and write the following:

[L]ook closely for very straight imprinted lines in the middle of flattened areas that appear slightly more grey. You can also see cracks, especially clearly on the right of the nodule in the image, but if you look around, you’ll find there are more of them. Some of the scratched areas are looking white, too. All those features will allow us an insight into the nodules and an interpretation beyond what we can otherwise see on the surface.

The image below, also taken by the right navigation camera and reduced to post here, looks back at Curiosity’s earlier travels, across the floor of Gale Crater about 1,500 feet below. The rim, about 25 miles away, can be seen through the atmospheric haze as the distant mountain chain.

See the orbital map at this post in September to get the context of what the two images are viewing. The top image looks south along the cliff line, the bottom looks almost due north.
Looking across Gale Crater
Click for full image.

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A collapsing north wall in Valles Marineris

2:05 pm

Mass wasting in Valles Marineris
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on July 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as an alluvial fan.

I have also seen them label this kind of avalanche as mass wasting, where the material moves down slope suddenly in a single mass.

The image shows the aftermath of such an event, after a large blob of material broke free from the mountainside and slid almost as a unit downhill to settle more than two miles away on the floor of the canyon. The distance traveled and the blobby nature of the flow both reveal how the lower Martian gravity changes the nature of such events, compared to what you might see on Earth. The flows can travel farther, and can hold together as a unit easier.

The overview map below not only provides the context, but it tells us that such events are remarkably common in this place.
» Read more

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The icy Phlegra Mountains on Mars

1:37 pm

Overview map

Cool image time! The Phlegra Mountains on Mars are probably the iciest mountains on the red planet, something I noted previously in an April 2020 essay, highlighting a half dozen images from the high resolution camera on Mars Reconnaissance Orbiter (MRO) that showed that iciness. As I stated:

Here practically every photograph taken by any orbiter appears to show immense glacial flows of some kind, with some glaciers coming down canyons and hollows [#1], some filling craters [#2], some forming wide aprons [#3] at the base of mountains and even at the mountains’ highest peaks [#4], and some filling the flats [#5] beyond the mountain foothills.

And then there are the images that show almost all these types of glaciers, plus others [#6].

The overview map above not only shows the locations of these six images in black, it also shows in red two of SpaceX’s four prime candidate landing sites for its Starship spacecraft. Note that #3 above is one of those sites.

The white rectangle in the Phlegra Mountains marks the location of today’s cool image below, taken on June 11, 2021 by MRO’S high resolution camera.
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Dry Martian chaos

1:52 pm

Dry chaos on Mars
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On Mars, one of the most common kinds of landscape is called chaos terrain. Made up of mesas, buttes, and cross-cutting random canyons, this geology is not seen on Earth, and when first identified by scientists in early orbital pictures in the 1970s, it baffled them. While it is clear that some form of erosion process caused it, the scientists did not have enough data then to figure out what that process was.

Today scientists have a rough theory, based on what they now know about Mars’ overall geology and its climate and orbital history. The canyons of chaos terrain were originally fault lines where either water or ice could seep through and widen. See this January 2020 post for a more detailed explanation.

Most of the cool images I have posted of chaos terrain have been in places in the mid-latitudes that are covered with glaciers. See for example this December 2019 post of one particular mesa in glacier country, with numerous glaciers flowing down its slopes on all sides. That mesa is quite typical of all such mesas in the mid-latitudes.

Today’s cool image above, cropped to post here, takes us instead to the Martian very dry equatorial regions. The photo was taken on May 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and like mid-latitude chaos, it shows a collection of random mesas with canyons cut almost randomly between.

Unlike the mid-latitudes, however, there is no evidence of glaciers here. Instead, the canyons and mesa slopes are covered with dust, shaped into wind-blown dunes.

As always, the overview map below gives us some context.
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Hubble data detects persistent water vapor on one of Europa’s hemispheres

1:30 pm

Using data from the Hubble Space Telescope spanning sixteen Earth years, scientists have detected the presence of water vapor on Europa, but strangely spread only across one of the moon’s hemispheres.

Previous observations of water vapor on Europa have been associated with plumes erupting through the ice, as photographed by Hubble in 2013. They are analogous to geysers on Earth, but extend more than 60 miles high. They produce transient blobs of water vapor in the moon’s atmosphere, which is only one-billionth the surface pressure of Earth’s atmosphere.

The new results, however, show similar amounts of water vapor spread over a larger area of Europa in Hubble observations spanning from 1999 to 2015. This suggests a long-term presence of a water vapor atmosphere only in Europa’s trailing hemisphere – that portion of the moon that is always opposite its direction of motion along its orbit. The cause of this asymmetry between the leading and trailing hemisphere is not fully understood.

First, it must be emphasized that the amounts of atmospheric water being discussed are tiny, so tiny that on Earth we might consider this a vacuum.

Second, that the water vapor is only seen on the trailing hemisphere suggests there is some sort of orbital influence involved, though what that influence is remains unknown.

Hopefully when Europa Clipper finally arrives in orbit around Jupiter in 2030, with a path that will fly past Europa fifty times, we will some clarity on these questions.

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A gecko on Mars

12:24 pm

Gecko on Mars
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Today’s cool image is also today’s picture of the day from the science team of the high resolution camera on Mars Reconnaissance Orbiter (MRO. That picture, rotated, cropped, and reduced to post here, can be seen to the right. As the caption authors Sharon Wilson and Sarah Sutton write:

The smooth volcanic surfaces in the Gordii Fossae region are sometimes interrupted by long, narrow troughs, or fissures. These fissures form when underground faults, possibly involving magma movement, reach the near-surface, allowing material to collapse into pits or an elongated trough. This fissure appears to have erupted material that flowed onto the surface.

If you use your imagination, this trough resembles a gecko with its long tail and web-shaped feet!

This impression is even more evident in the wider image taken by MRO’s context camera below.
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Dusty chaos in Martian canyons

1:37 pm

Outcrops in dusty chaos on Mars
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Cool image time! The photo to the right, cropped and reduced to post here, was taken on May 30, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the dusty dry floor of the chaos region of rough terrain in a side canyon of Valles Marineris, near its outlet. The color strip and the bright outcrops suggest that this terrain contains interesting minerals and resources. To determine exactly what those materials are however requires more information not available in this photo.

This ancient chaos terrain is the leftover eroded sea floor of a intermittent inland sea, leftover water from the catastrophic floods that are theorized to have flowed out of Valles Marineris and carved its gigantic canyons.

The overview map below shows this hypothesized sea.
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Ancient fossil river in the very dry equatorial regions of Mars

1:27 pm

Inverted Channel on Mars
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Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on August 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label an “inverted channel in Arabia Terra,” a small example of the more than 10,000 miles of fossilized rivers in this region on Mars that scientists have identified using MRO.

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. [emphasis mine]

Since this fossilized river is located at 11 degrees north latitude, smack in the middle of the dry equatorial regions of Mars, it has certainly been a dry desert for a very long time. You can see how barren the terrain appears by looking at the wider view afforded by MRO’s context camera below.
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