The Earth and Moon, as seen by Mars Express in Mars orbit

The Earth and Moon, as seen from Mars
Click to see four image movie.

The science team for Europe’s Mars Express orbiter recently turned the spacecraft’s camera upward to capture a sequence of four images of the Earth with the Moon circling around it.

The images were taken at 14:08, 03:10 and 19:49 UTC on 15, 21, 27 May 2023 respectively, and at 15:00 UTC on 2 June 2023. This covers a bit more than half of the Moon’s monthly motion around the Earth. The distance between Earth and Mars varied from 279 186 624 km to 301 016 265 km during this time. The image resolution is about 2570 km per pixel.

To the right is the June 2nd image, cropped and enhanced to post there. The Earth is the larger spot to the left. The picture gives a sense of what the Earth-Moon double planet system looks like from Mars. Unlike all other planets, where the size difference between planet and moon is great, the Earth/Moon system is comprised of a Moon quite large in comparison to its central planet.

ESA to live-stream image downloads from Mars Express

To celebrate Mars Express’s 20th year in orbit around Mars, the European Space Agency (ESA) has announced that tomorrow it will for one hour live-stream the image downloads coming from the orbiter.

I have embedded that live stream below. According to the press release, new images will arrive about once every 50 seconds. The camera that will be taking the pictures however is not one of Mars Express’s main instruments, but designed instead to simply monitor the separation of the Beagle-2 lander from the orbiter in 2003. Since 2007 however the science team has used its low resolution global images of Mars for public relations, education, and even some science research.

That the science team is not providing the live feed from its high resolution camera however illustrates why Mars Express gets so little press coverage, compared to Mars Reconnaissance Orbiter (MRO). All MRO images are released to the public, usually only a month or so after they reach Earth. The ESA however has never made the archive of Mars Express accessible, as far as I have been able to discover. All it does is periodically issue a press release about once every few months touting one new image, even though the spacecraft is taking dozens daily.
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Crater at the edge of the Martian south pole ice cap

Oblique view of south pole crater
Click for full image.

Overview map

Cool image time! The oblique panorama above, reduced and sharpened to post here, was created from an image taken on May 19, 2022 by the European orbiter Mars Express. Its location on edge of the layered deposits of ice and dust that form most of the Martian southern ice cap is indicated by the white rectangle on the overview map to the right. From the press release:

While it may look like a winter wonderland, it was southern hemisphere spring at the time and ice was starting to retreat. Dark dunes are peeking through the frost and elevated terrain appears ice-free.

Two large impact craters draw the eye, their interiors striped with alternating layers of water-ice and fine sediments. These ‘polar layered deposits’ are also exposed in exquisite detail in the rusty red ridge that connects the two craters.

The scattered white patches are either water frost, or the winter mantle of dry ice, both now sublimating away with the coming of spring.

The black line on the overview map indicates the extent of the layered deposits, and suggest that the ridgeline is not considered part of that ice cap layer, in contradiction to the press release language above.

Which is it? I would guess the answer is simply the uncertainty of science. Some scientists took a look here and decided the ridge was actually a base layer sticking up through the layered deposits. The European scientists who took this picture have instead concluded, based on the image, that the ridge is part of the layer deposits.

A global map of Mars’ future mining regions

A global map of Mars' future mining regions
Click for labeled image.

Using data accumulated in the past decade from orbiters, scientists have now published a global map of Mars, showing the regions on the red planet where there are high concentrations of hydrated minerals, minerals formed in the past in conjunction with the presence of water.

The maps to the right show those regions in various colors, indicating different types of minerals.

On Earth, clays form when water interacts with rocks, with different conditions giving rise to different types of clays. For example, clay minerals such as smectite and vermiculite form when relatively small amounts of water interact with the rock and so retain mostly the same chemical elements as the original volcanic rocks. In the case of smectite and vermiculite those elements are iron and magnesium. When the amount of water is relatively high, the rocks can be altered more. Soluble elements tend to be carried away leaving behind aluminium-rich clays such as kaolin.

The big surprise is the prevalence of these minerals. Ten years ago, planetary scientists knew of around 1000 outcrops on Mars. This made them interesting as geological oddities. However, the new map has reversed the situation, revealing hundreds of thousands of such areas in the oldest parts of the planet.

Though this data once again suggests that liquid water once flowed on the surface of Mars, for future colonists it is more important in that it identifies the regions where the most valuable resources will likely be found. For example, most of the colored regions on the map are located in the dry equatorial parts of Mars. However, south of the giant canyon Valles Marineris is a mineral region at about 30 to 40 degrees south latitude, to the northwest of Argyre Basin. This is also a region with a high concentration of glacial features. The two combined will likely make this region very valuable real estate.

Glaciers in the Phlegra Mountains on Mars

Glaciers in the Phlegra mountains
Click for full image.

Cool image time! The photo to the right, cropped to post here, is just one of the many hundreds taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) as well as Europe’s Mars Express orbiter showing the thick icy glacial flows that surround practically every mountain or hill in the Phlegra mountains of Mars.

This picture was taken on November 3, 2021, and shows the eroding foot of an eroding glacial flow coming down from a small hill in a southeastern part of these mountains dubbed Phlegra Dorsa. The downward grade is to the north.

At 30 degrees north latitude it is not surprising these glacial flows are eroding, as they are at the southernmost limit of the mid-latitudes bands where such glaciers are found. Closer to the equator scientists have yet to find much evidence of ice.

The repeating arcs at the foot of this glacier suggest that it pushed downward in cycles, with each later cycle traveling a shorter distance. This supposition makes sense, considering scientists think the ebb and flow of these Martian glaciers has been determined by the cyclical changes in the planet’s rotational tilt.

The overview map below not only gives the context, it shows this location relative to the candidate landing sites for SpaceX’s Starship spacecraft.
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Mars Express successfully relays data from Zhurong to Earth

The European Space Agency’s Mars Express orbiter has successfully been used to relay data from China’s Zhurong Mars rover to Earth and then to China.

In November, ESA’s Mars Express and CNSA’s Zhurong teams carried out a series of experimental communication tests in which Mars Express used this ‘in the blind’ mode to listen for signals sent to it by the Zhurong Rover.

The experiments culminated in a successful test on 20 November. “Mars Express successfully received the signals sent by the rover, and our colleagues in the Zhurong team confirmed that all the data arrived on Earth in very good quality.” says ESA’s Gerhard Billig.

Apparently, normal communications would first involve “handshake” communications between the two, but that requires communications frequencies Zhurong does not use. Mars Express instead had to grab the data on the blind. The test was a success, which means the ESA will likely act as another communications relay for Zhurong, in addition to China’s Tianwen-1 orbiter, as the rover’s mission on Mars continues.

Zhurong’s continuing travels on Mars

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.

Scientists question existence of liquid water lake under Martian south pole

The uncertainty of science: A re-analysis of the ground-penetrating radar data that suggested there was a liquid water lake under the Martian south pole has found that it might not be liquid water at all, but either “clays, metal-bearing minerals, or saline ice.”

The abstract can be read here.

The radar data, obtained by the European orbiter Mars Express, definitely shows a layer of bright reflection suggesting a layer of something different below the icecap. The research team decided to find out if other things besides liquid water could cause the difference.

They were able to determine what level of electric conductivity the material below the ice would need to have to match the observed signal from MARSIS. Then, they identified materials that are both conductive and present on Mars including clays, metal-bearing minerals and saline ice. “Salty ice or conductive minerals at the base of the ice sheet are less flashy, but are more in line with the extremely cold temperatures at Mars’ poles,” Bierson said.

While not explicitly excluding a liquid brine, the results open new potential explanations for the observed strong radar reflections, some of which do not require liquid brine beneath the Martian south polar ice cap.

Nothing is proven, one way or another. This research has simply underlined the uncertainty of the liquid water claim. We simply do not know what caused the bright radar reflection. All we know for certainty is that it is there.

Scientists: Mars is losing water seasonally through its atmosphere

The uncertainty of science: Two new studies using data Europe’s Trace Gas Orbiter and Mars Express orbiters have found that Mars is losing water seasonally through its atmosphere.

The studies also found that global dust storms accelerate the process.

Anna and colleagues found that water vapour remained confined to below 60 km when Mars was far from the Sun but extended up to 90 km in altitude when Mars was closest to the Sun. Across a full orbit, the distance between the Sun and the Red Planet ranges from 207 million to 249 million km.

Near the Sun, the warmer temperatures and more intensive circulation in the atmosphere prevented water from freezing out at a certain altitude. “Then, the upper atmosphere becomes moistened and saturated with water, explaining why water escape rates speed up during this season – water is carried higher, aiding its escape to space,” adds Anna.

In years when Mars experienced a global dust storm the upper atmosphere became even wetter, accumulating water in excess at altitudes of over 80 km.

But wait, didn’t planetary scientists just announce that Mars hasn’t lost its water through the atmosphere, but instead lost it when it became chemical trapped in the planet’s soil? Yup, they did, but that was a model based on new ground data. This new result is based on atmospheric data.

Or to put it another way, the model was incomplete. While it could be true that a large bulk of Mars’ water is trapped chemically in the ground, that is not proven, only hypothesized. What has been proven, and is now confirmed by these two studies, is that, depending on weather and season, the water of Mars does leak into its upper atmosphere where it can escape into space, never to return.

What remains unknown is how much water escaped into space, and when. Moreover, the ground-based model could still be right, even if it is true that Mars is losing water through its atmosphere. At the moment the data is too incomplete to answer these questions with any certainty.

Meanwhile, this press release once again gives the false impression that the only water left on Mars is at its poles (and in this case, only the south pole). This is not accurate, based on numerous studies finding evidence of buried ice and glaciers everywhere on the planet down to the 30th latitude, in both the north and south hemispheres. Mars might have far less water now than it did billions of years ago, but it still has plenty, and that water is not found only at the poles.

A majestic terraced butte on Mars

Majestic butte on Mars
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on September 8, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an outstanding terraced butte that would rival any of the similar buttes scattered throughout the Grand Canyon, and is reminiscent especially of Wotans Throne.

What makes this butte intriguing are its terraces, the obvious result of the repeated deposition of new layers across the surface over time, and now exposed by erosion. What caused them?

As always, location provides the clues. First, this butte is found at about 15 degrees north latitude in the vast Arabia Terra transition region between the Martian northern lowland plains and the southern cratered highlands. At that latitude, we are not looking at any recent glacial features. While there might have been ice here once, it hasn’t likely been present, either on the surface or underground, for a very long time.

This conclusion becomes important once we look at the wider photo below, taken by the high resolution camera on the European orbiter Mars Express. This image gives us the immediate context.
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New study confirms liquid water under Mars’ south pole

A new study has confirmed earlier work that suggested there were liquid lakes of water under the Martian south pole.

The data appears to indicate that the bodies are “hypersaline solutions” –a brine in which high concentrations of salt are dissolved in water – which is perhaps the reason they are able to stay liquid despite the very cold conditions of Mars’s south pole.

The fact that there is a whole set of lakes suggests that they have probably formed relatively easily, and that versions of them may therefore have been present throughout the history of the planet. [emphasis mine]

There is one problem with hypothesis indicated by the highlighted words. Mars’ rotational tilt (its obliquity) shifts significantly, from 0 to 60 degrees. Right now it is tilted about 25 degrees, similar to Earth. The south pole as we see it today will have been very different at different obliquities, which means there is no way to assume these posited underground lakes would have been there.

European planetary missions go dark because of Wuhan virus

The European Space Agency has suspended operations and shut down several planetary missions, including two Mars orbiters and two solar missions, because of lockdowns imposed because of COVID-19.

The problem is that they don’t have enough people in their mission controls to operate everything. They are shutting these down so that they can continue operations on their Mecury mission BepiColumbo, for example.

The article also tries to lay the blame for the recently announced launch delay of Europe’s Mars 2020 rover to 2022 on the virus, but that’s false. The mission was delayed because it simply wasn’t ready.

Mars Express confirms ancient glaciers in northern Martian mid-latitudes

Perspective view of Deuteronilus Mensae
Click for full image.

The European Space Agency’s orbiter Mars Express has confirmed the presence of large fractured ice sheets suggestive of buried and ancient glaciers. These ice sheets are within one region on Mars located in the mid-latitudes where many such glacial features have been found. They are also in the transition zone between the northern lowlands and the southern highlands.

This landscape shows clear and widespread signs of significant, lasting erosion. As is common with fretted terrain, it contains a mix of cliffs, canyons, scarps, steep-sided and flat-topped mounds (mesa), furrows, fractured ridges and more, a selection of which can be seen dotted across the frame.

These features were created as flowing material dissected the area, cutting through the existing landscape and carving out a web of winding channels. In the case of Deuteronilus Mensae, flowing ice is the most likely culprit. Scientists believe that this terrain has experienced extensive past glacial activity across numerous martian epochs.

It is thought that glaciers slowly but surely ate away at the plains and plateaus that once covered this region, leaving only a scattering of steep, flat, isolated mounds of rock in their wake.

Smooth deposits cover the floor itself, some marked with flow patterns from material slowly moving downhill – a mix of ice and accumulated debris that came together to form and feed viscous, moving flows of mass somewhat akin to a landslide or mudflow here on Earth.

Studies of this region by NASA’s Mars Reconnaissance Orbiter [MRO] have shown that most of the features seen here do indeed contain high levels of water ice. Estimates place the ice content of some glacial features in the region at up to 90%. This suggests that, rather than hosting individual or occasional icy pockets and glaciers, Deuteronilus Mensae may actually represent the remnants of an old regional ice sheet. This ice sheet may once have covered the entire area, lying atop the plateaus and plains. As the martian climate changed this ice began to shift around and disappear, slowly revealing the rock beneath.

Overall, the data coming from both Mars Express and MRO increasingly suggests that there is a lot of buried glacial ice in the mid-latitudes. Mars might be a desert, but it is increasingly beginning to look like much of the planet is a desert like Antarctica, not the Sahara.

Both methane and oxygen fluctuate in unison seasonally in Gale Crater

The uncertainty of science: According to a new science paper, data from Curiosity on Mars has now found that both methane and oxygen fluctuate in unison seasonally in Gale Crater.

From the paper’s abstract:

[T]he annual average composition in Gale Crater was measured as 95.1% carbon dioxide, 2.59% nitrogen, 1.94% argon, 0.161% oxygen, and 0.058% carbon monoxide. However, the abundances of some of these gases were observed to vary up to 40% throughout the year due to the seasonal cycle. Nitrogen and argon follow the pressure changes, but with a delay, indicating that transport of the atmosphere from pole to pole occurs on faster timescales than mixing of the components. Oxygen has been observed to show significant seasonal and year‐to‐year variability, suggesting an unknown atmospheric or surface process at work. These data can be used to better understand how the surface and atmosphere interact as we search for signs of habitability.

The data shows that the unexpected and so far unexplained seasonal oxygen fluctuation appears to track the same seasonal methane fluctuations. While biology could cause this signature, so could geological processes, though neither can produce these fluctuations easily.

Meanwhile, adding to the uncertainty were results from the two European orbiters, Mars Express and Trace Gas Orbiter. Both have failed to detect a June 19, 2019 dramatic spike in methane that had been measured by Curiosity.

Mars Express looks at Martian river relic

Mars Express perspective view of Nirgal Vallis
Click for full image.

The Mars Express science team today released a mosaic produced by the orbiter’s high resolution camera of the 300 hundred mile long relic river valley Nirgal Vallis. The image to the right, reduced to post here, is the oblique view that was produced by computer using the camera’s stereo images.

This ancient valley system is named Nirgal Vallis, and was once filled with running water that spread across Mars. By exploring the characteristics of the surrounding craters, scientists estimate the system’s age to be between 3.5 and 4 billion years old.

The part of Nirgal Vallis captured in these images lies towards the western end of the river system, where it is slowly spreading out and dissipating; the eastern end is far less branched and more clearly defined as a single valley, and opens out into the large Uzboi Vallis – the suspected location of a large, ancient lake that has long since dried up.

Nirgal Vallis is a typical example of a feature known as an amphitheatre-headed valley. As the name suggests, rather than ending bluntly or sharply, the ends of these tributaries have the characteristic semi-circular, rounded shape of an Ancient Greek amphitheatre. Such valleys also typically have steep walls, smooth floors, and, if sliced through at a cross-section, adopt a ‘U’ shape. The valleys pictured here are about 200 m deep and 2 km wide, and their floors are covered in sandy dunes; the appearance of these dunes indicates that martian winds tend to blow roughly parallel to the valley walls.

Unlike the high resolution camera on Mars Reconnaissance Orbiter (MRO), which is for taking close-up images of specific surface features, Mars Express is producing a high resolution survey of the entire planet. Its camera does not have quite the same resolution, but as it is taking wider images that’s okay.

What is unfortunate is the European Space Agency’s policy for releasing those images. Unlike MRO, they do not make them all available to the public instantly. Instead, they periodically do press releases like today’s, highlighting a specific region or single large feature. As a result, Mars Express does not get the press it deserves.

The glaciers of Mars

The glaciers on Mars

For the future colonists of Mars, the question of finding water will not be that much of a problem. Not only have planetary geologists mapped out the existence of extensive water-ice in the Martian poles, they have found that the planet apparently has widespread glacier deposits in two mid-latitude belts from 30 to 60 degrees latitude.

The question will be whether those Martian settlers will be able to easily access this water. The data so far suggests that much of the Martian underground water at high latitudes is likely mixed with dust and debris. Extracting it might not be straightforward. There are hints that the ice table at latitudes about 55 degrees might be more pure, but could be somewhat deep below ground, requiring the settlers to become miners to obtain their water. Moreover, all these high latitude locations are in environments that are more hostile, and therefore more difficult to establish a colony.

What about the glaciers? The global map of Mars above, reduced and annotated to post here, shows what are believed to be extensive glacial deposits at lower latitudes, and comes from a recently published paper on the subject. The different colors indicate the different types of glacial deposits the scientists have identified.

Green and yellow indicate what scientists call lineated valley fill (LVF) and lobate debris aprons (LDA) respectively, glacial deposits found in the transition zone between the southern highlands and either the northern lowland plains or the basins of the southern hemisphere, Hellas and Argyre. These glaciers are in many ways most similar to glaciers found on Earth, flows heading downhill along natural geographic features.

Magenta represents concentric crater fill (CCF), glacier features which seem very evenly distributed across both the northern and southern lower mid-latitude belts. Here scientists appear to have detected buried ice within the floors of craters.

The paper which included this map focused on describing a new glacial feature, something they dubbed valley fill deposits (VFD), that they had found so far in only one place, as indicated by the black square on the map.

The photograph below and on the right, reduced and cropped to post here, is from figure two of the linked paper.
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Chaos on Mars

Aurorae Chaos in Margaritifer Terra
Click for full image.

The Mars Express science team today released a digital perspective view of the chaos terrain located in the outlet region for the vast drainages, which include Marineris Valles, coming down from the Tharsis Bulge volcanic region that holds Mars’ largest volcanos.

The view, reduced to post here on the right, was created from a image taken by Mars Express on October 31, 2018. This chaos terrain is south of the various examples of chaos terrain previously highlighted here on Behind the Black (May 14, 2018, June 26, 2018, March 11, 2019, March 14, 2019). As they note,

The division between the chaotic terrain and plains can also be seen clearly in these images. The left (south) side of the image is notably smoother and more featureless than the jumbled right (north) side, and the two regions are split by a prominent line carving diagonally across the frame. The transition area around this scarp is especially broken and fractured; this is thought to be caused as the martian crust stretched and moved.

The ancient chaotic terrain we see on Mars holds information about how water once permeated and interacted with the planetary surface, including how it was transported, stored, and released.

Chaotic terrain is thought to have formed as chunks of the martian surface collapsed in dramatic events triggered by the heating of material containing ice or water-bearing minerals – possibly due to climatic or volcanic heat sources, or an impact from an asteroid or comet. This released large amounts of water, causing the terrain above to subside. The water then drained away quickly, leaving behind the messy, broken patterns seen in regions such as Aurorae Chaos, which is thought to have formed some 3.5 billion years ago.

Mars Express images don’t quite have the resolution of the high resolution images from Mars Reconnaissance Orbiter, but they cover a wider area, so that the spacecraft has now photographed almost the entire Martian surface since its arrival in Mars orbit in December 2003.

Liquid water found beneath Martian south pole

Data from Europe’s Mars Express orbiter has detected a pond of liquid water buried beneath the Martian south pole.

The radar investigation shows that south polar region of Mars is made of many layers of ice and dust down to a depth of about 1.5 km in the 200 km-wide area analysed in this study. A particularly bright radar reflection underneath the layered deposits is identified within a 20 km-wide zone.

Analysing the properties of the reflected radar signals and considering the composition of the layered deposits and expected temperature profile below the surface, the scientists interpret the bright feature as an interface between the ice and a stable body of liquid water, which could be laden with salty, saturated sediments. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimetres thick.

The data here is somewhat uncertain, but is also not to be dismissed. It is very likely this is liquid water.

I must add that this is not really a big surprise. Many scientists expected this. Also, this water is not very accessible, and is also located at the pole, the Mars’s harshest environment. Just because it is liquid is not a reason to aim to mine it. There is plenty of evidence of ice in much more accessible and reasonable locations.

What this discovery suggests is that it is possible to have liquid water on Mars. The great geological mystery of the planet is while that much of its geology appears formed by flowing water, scientists have not been able to devise good climate histories that make that flowing water possible. This discovery helps those scientists in devising those histories.

Is it a volcano or an impact crater? Mars Express wants to know!

Europe’s Mars Express orbiter has taken a high resolution image of Ismenia Patera, a very large crater located in the Arabia Terra region of Mars, the largest part of the transition zone between the low flat northern plains and the high rough southern terrain.

The crater is intriguing to scientists because they are not sure if it was created by an impact, or a volcano.

Certain properties of the surface features seen in Arabia Terra suggest a volcanic origin: for example, their irregular shapes, low topographic relief, their relatively uplifted rims and apparent lack of ejected material that would usually be present around an impact crater.

However, some of these features and irregular shapes could also be present in impact craters that have simply evolved and interacted with their environment in particular ways over time.

There is also additional evidence that this region was once home to volcanic activity. If so, that activity would have changed the terrain, and thus made its geological history more complex and difficult to decipher, a fact that is important since this is also a region that might have been at the edge of theorized northern Martian Ocean.

More evidence of giant flash floods on Mars

Mangala Valles

A newly released image from ESA’s Mars Express orbiter shows that catastrophic flooding — caused by ice melted from volcanic activity — created the Mangala Valles channels on Mars.

The perspective image on the right shows the topography of the region, with low points indicated in blue and high points by red. The channel along the right side of the image is Mangala Valles itself, though you can also see additional flood channels to the left of it passing around and through a large crater whose floor now stands above the surrounding terrain caused by the erosion of the rim plus the deposit of sediment inside the crater during the flooding.

I have a soft spot for Mangala Valles. When it was first photographed by the first orbiter missions to Mars in the early 1970s I was struck by its river-like appearance and striking topography. I therefore placed my Martian colony here in one of my efforts at science fiction writing. I figured it a good location for colonization, as there would likely be water and, by roofing over the deep canyon, a colony could be built relatively easily.

Better locations on Mars have since been found, but the location still intrigues me.

Mars Express will do an extremely close flyby of the martian moon Phobos on December 29.

Mars Express will do an extremely close flyby of the martian moon Phobos on December 29.

Late this month, ESA’s Mars Express will make the closest flyby yet of the Red Planet’s largest moon Phobos, skimming past at only 45 km [28 miles] above its surface. The flyby on 29 December will be so close and fast that Mars Express will not be able to take any images, but instead it will yield the most accurate details yet of the moon’s gravitational field and, in turn, provide new details of its internal structure.

In celebration of its tenth year in orbit, scientists running the Mars Express mission have released global mineral maps of Mars.

In celebration of its tenth year in orbit, scientists running the Mars Express mission have released global mineral maps of Mars. With video.

The unique atlas comprises a series of maps showing the distribution of minerals formed in water, by volcanic activity, and by weathering to create the dust that makes Mars red. They create a global context for the dominant geological processes that sculpted the planet we see today.

Take a look at the video. It is fascinating to see where these minerals concentrate.

Mars Express has found more evidence that Mars once had oceans.

Mars Express has found more evidence that Mars once had oceans.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted following a large impact, creating outflow channels that drained the water into areas of low elevation.

“MARSIS penetrates deep into the ground, revealing the first 60–80 metres of the planet’s subsurface,” says Wlodek Kofman, leader of the radar team at IPAG. “Throughout all of this depth, we see the evidence for sedimentary material and ice.” The sediments revealed by MARSIS are areas of low radar reflectivity. Such sediments are typically low-density granular materials that have been eroded away by water and carried to their final destination.

This later ocean would however have been temporary. Within a million years or less, Dr Mouginot estimates, the water would have either frozen back in place and been preserved underground again, or turned into vapour and lifted gradually into the atmosphere. “I don’t think it could have stayed as an ocean long enough for life to form.”

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