samedi 8 août 2020

Breaking new ground in the search for dark matter

CERN - European Organization for Nuclear Research logo.

August 8, 2020

The Large Hadron Collider (LHC) is renowned for the hunt for and discovery of the Higgs boson, but in the 10 years since the machine collided protons at an energy higher than previously achieved at a particle accelerator, researchers have been using it to try to hunt down an equally exciting particle: the hypothetical particle that may make up an invisible form of matter called dark matter, which is five times more prevalent than ordinary matter and without which there would be no universe as we know it. The LHC dark-matter searches have so far come up empty handed, as have non-collider searches, but the incredible work and skill put by the LHC researchers into finding it has led them to narrow down many of the regions where the particle may lie hidden – necessary milestones on the path to a discovery.

Image above: Hubble image of Ultra Deep Field 2014. Image Credits: NASA, ESA, H.Teplitz and M.Rafelski (IPAC/Caltech), 
A. Koekemoer (STScI), R. Windhorst (ASU), Z. Levay (STScI).

“Before the LHC, the space of possibilities for dark matter was much wider than it is today,” says dark-matter theorist Tim Tait of UC Irvine and theory co-convener of the LHC Dark Matter Working Group.

“The LHC has really broken new ground in the search for dark matter in the form of weakly interacting massive particles, by covering a wide array of potential signals predicted by either production of dark matter, or production of the particles mediating its interactions with ordinary matter. All of the observed results have been consistent with models that don’t include dark matter, and give us important information as to what kinds of particles can no longer explain it. The results have both pointed experimentalists in new directions for how to search for dark matter, and prompted theorists to rethink existing ideas for what dark matter could be – and in some cases to come up with new ones.”

Image above: Simulation of the dark-matter distribution in the universe. (V. Springel et al. 2005).

Make it, break it and shake it

To look for dark matter, experiments essentially “make it, break it or shake it”. The LHC has been trying to make it by colliding beams of protons. Some experiments are using telescopes in space and on the ground to look for indirect signals of dark-matter particles as they collide and break themselves out in space. Others still are chasing these elusive particles directly by searching for the kicks, or “shakes”, they give to atomic nuclei in underground detectors.

The make-it approach is complementary to the break-it and shake-it experiments, and if the LHC detects a potential dark-matter particle, it will require confirmation from the other experiments to prove that it is indeed a dark-matter particle. By contrast, if the direct and indirect experiments detect a signal from a dark-matter particle interaction, experiments at the LHC could be designed to study the details of such an interaction.

Missing-momentum signal and bump hunting

o how has the LHC been looking for signs of dark-matter production in proton collisions? The main signature of the presence of a dark-matter particle in such collisions is the so-called missing transverse momentum. To look for this signature, researchers add up the momenta of the particles that the LHC detectors can see – more precisely the momenta at right angles to the colliding beams of protons – and identify any missing momentum needed to reach the total momentum before the collision. The total momentum should be zero because the protons travel along the direction of the beams before they collide. But if the total momentum after the collision is not zero, the missing momentum needed to make it zero could have been carried away by an undetected dark-matter particle.

Missing momentum is the basis for two main types of search at the LHC. One type is guided by so-called complete new physics models, such as supersymmetry (SUSY) models. In SUSY models, the known particles described by the Standard Model of particle physics have a supersymmetric partner particle with a quantum property called spin that differs from that of its counterpart by half of a unit. In addition, in many SUSY models, the lightest supersymmetric particle is a weakly interacting massive particle (WIMP). WIMPs are one of the most captivating candidates for a dark-matter particle because they could generate the current abundance of dark matter in the cosmos. Searches targeting SUSY WIMPs look for missing momentum from a pair of dark-matter particles plus a spray, or “jet”, of particles and/or particles called leptons.

Image above: An ATLAS detector event with missing transverse momentum. A photon with transverse momentum of 265 GeV (yellow bar) is balanced by 268 GeV of missing transverse momentum (red dashed line on the opposite side of the detector). (Image: ATLAS/CERN).

Another type of search involving the missing-momentum signature is guided by simplified models that include a WIMP-like dark-matter particle and a mediator particle that would interact with the known ordinary particles. The mediator can be either a known particle, such as the Z boson or the Higgs boson, or an unknown particle. These models have gained significant traction in recent years because they are very simple yet general in nature (complete models are specific and thus narrower in scope) and they can be used as benchmarks for comparisons between results from the LHC and from non-collider dark-matter experiments. In addition to missing momentum from a pair of dark-matter particles, this second type of search looks for at least one highly energetic object such as a jet of particles or a photon.

In the context of simplified models, there’s an alternative to missing-momentum searches, which is to look not for the dark-matter particle but for the mediator particle through its transformation, or “decay”, into ordinary particles. This approach looks for a bump over a smooth background of events in the collision data, such as a bump in the mass distribution of events with two jets or two leptons.

Narrowing down the WIMP territory

What results have the LHC experiments achieved from these WIMP searches? The short answer is that they haven’t yet found signs of WIMP dark matter. The longer answer is that they have ruled out large chunks of the theoretical WIMP territory and put strong limits on the allowed values of the properties of both the dark-matter particle and the mediator particle, such as their masses and interaction strengths with other particles. Summarising the results from the LHC experiments, ATLAS experiment collaboration member Caterina Doglioni says “We have completed a large number of dedicated searches for invisible particles and visible particles that would occur in processes involving dark matter, and we have interpreted the results of these searches in terms of many different WIMP dark-matter scenarios, from simplified models to SUSY models. This work benefitted from the collaboration between experimentalists and theorists, for example on discussion platforms such as the LHC Dark Matter Working Group (LHC DM WG), which includes theorists and representatives from the ATLAS, CMS and LHCb collaborations. Placing the LHC results in the context of the global WIMP search that includes direct- and indirect-detection experiments has also been a focus of discussion in the dark-matter community, and the discussion continues to date on how to best exploit synergies between different experiments that have the same scientific goal of finding dark matter.”

Giving a specific example of a result obtained with data from the ATLAS experiment, Priscilla Pani, ATLAS experiment co-convener of the LHC Dark Matter WG, highlights how the collaboration has recently searched the full LHC dataset from the machine’s second run (Run 2), collected between 2015 and 2018, to look for instances in which the Higgs boson might decay into dark-matter particles. “We found no instances of this decay but we were able to set the strongest limits to date on the likelihood that it occurs,” says Pani.

Phil Harris, CMS experiment co-convener of the LHC Dark Matter Working Group, highlights searches for a dark-matter mediator decaying into two jets, such as a recent CMS search based on Run 2 data.

“These so-called dijet searches are very powerful because they can probe a large range of mediator masses and interaction strengths,” says Harris.

Xabier Cid Vidal, LHCb experiment co-convener of the LHC Dark Matter WG, in turn notes how data from Run 1 and Run 2 on the decay of a particle known as the Bs meson has allowed the LHCb collaboration to place strong limits on SUSY models that include WIMPs. “The decay of the Bs meson into two muons is very sensitive to SUSY particles, such as SUSY WIMPs, because the frequency with which the decay occurs can be very different from that predicted by the Standard Model if SUSY particles, even if their masses are too high to be directly detected at the LHC, interfere with the decay,” says Cid Vidal.

Casting a wider net

“10 years ago, experiments (at the LHC and beyond) were searching for dark-matter particles with masses above the proton mass (1 GeV) and below a few TeV.  That is, they were targeting classical WIMPs such as those predicted by SUSY. Fast forward 10 years and dark-matter experiments are now searching for WIMP-like particles with masses as low as around 1 MeV and as high as 100 TeV,” says Tait. “And the null results from searches, such as at the LHC, have inspired many other possible explanations for the nature of dark matter, from fuzzy dark matter made of particles with masses as low as 10−22 eV to primordial black holes with masses equivalent to several suns. In light of this, the dark-matter community has begun to cast a wider net to explore a larger landscape of possibilities.”

Image above: The possible explanations for the nature of dark matter. (Image: G. Bertone and T. M. P. Tait).

On the collider front, the LHC researchers have begun to investigate some of these new possibilities. For example, they have started looking at the hypothesis that dark matter is part of a larger dark sector with several new types of dark particles. These dark-sector particles could include a dark-matter equivalent of the photon, the dark photon, which would interact with the other dark-sector particles as well as the known particles, and long-lived particles, which are also predicted by SUSY models.

“Dark-sector scenarios provide a new set of experimental signatures, and this is a new playground for LHC physicists,” says Doglioni.

“We are now expanding upon the experimental methods that we are familiar with, so we can try to catch rare and unusual signals buried in large backgrounds. Moreover, many other current and planned experiments are also targeting dark sectors and particles interacting more feebly than WIMPs. Some of these experiments, such as the newly approved FASER experiment, are sharing knowledge, technology and even accelerator complex with the main LHC experiments, and they will complement the reach of LHC searches for non-WIMP dark matter, as shown by the CERN Physics Beyond Colliders initiative.”

Finally, the LHC researchers are still working on data from Run 2, and the data gathered so far, from Run 1 and Run 2, is only about 5% of the total that the experiments will record. Given this, as well as the immense knowledge gained from the many LHC analyses thus far conducted, there’s perhaps a fighting chance that the LHC will discover a dark-matter particle in the next 10 years. “It’s the fact we haven’t found it yet and the possibility that we may find it in the not-so-distant future that keeps me excited about my job,” says Harris. “The last 10 years have shown us that dark matter might be different from what we had initially thought, but that doesn’t mean it is not there for us to find,” says Cid Vidal.

“We will leave no stone unturned, no matter how big or small and how long it will take us,” says Pani.

CERN in 3 Minutes


CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 23 Member States.

Further reading:

A new era in the search for dark matter:

Searching for Dark Matter with the ATLAS detector:

Related links:

Dark matter:

Standard Model:

LHC Dark Matter Working Group (LHC DM WG):

Strong limits on SUSY models:

FASER experiment:

CERN Physics Beyond Colliders initiative:

For more information about European Organization for Nuclear Research (CERN), Visit:

Images (mentioned), Video (CERN 2009), Text, Credits: CERN/Ana Lopes.

Best regards,

NASA Maps Beirut Blast Damage

NASA & JPL-Caltech - ARIA Mission logo.

August 8, 2020

Scientists are using satellite data to map ground surface changes in the aftermath of the recent explosion.

Image above: NASA's ARIA team, in collaboration with the Earth Observatory of Singapore, used satellite data to map the extent of likely damage following a massive explosion in Beirut. Dark red pixels represent the most severe damage. Areas in orange are moderately damaged, and areas in yellow are likely to have sustained somewhat less damage. Each colored pixel represents an area of 30 meters (33 yards). The map contains modified Copernicus Sentinel data processed by ESA (European Space Agency) and analyzed by ARIA team scientists at NASA's Jet Propulsion Laboratory, Caltech, and Earth Observatory of Singapore. Based in Pasadena, California, Caltech manages JPL for NASA.

NASA's Advanced Rapid Imaging and Analysis (ARIA) team, in collaboration with the Earth Observatory of Singapore, used satellite-derived synthetic aperture radar data to map the likely extent of damage from a massive Aug. 4 explosion in Beirut. Synthetic aperture radar data from space shows ground surface changes from before and after a major event like an earthquake. In this case, it is being used to show the devastating result of an explosion.

On the map, dark red pixels - like those present at and around the Port of Beirut - represent the most severe damage. Areas in orange are moderately damaged and areas in yellow are likely to have sustained somewhat less damage. Each colored pixel represents an area of 30 meters (33 yards).

Maps like this one can help identify badly damaged areas where people may need assistance. The explosion occurred near the city's port. It claimed more than 150 lives and is estimated to have caused billions of dollars' worth of damage.

The map contains modified Copernicus Sentinel data processed by ESA (European Space Agency) and analyzed by ARIA team scientists at NASA JPL, Caltech, and Earth Observatory of Singapore. Located in Pasadena, California, Caltech manages JPL for NASA.

Related article:

Satellite "Kanopus-V" captured the consequences of the explosion in the port of Beirut

More information on ARIA can be found here:

Image (mentioned), Text, Credits: NASA/JPL/Ian J. O'Neill/Jane J. Lee.


SpaceX Starlink 9 launched in to orbit

SpaceX - Falcon 9 / Starlink Mission patch.

August 8, 2020

SpaceX Starlink 9 launch

A SpaceX Falcon 9 rocket launched 57 Starlink satellites (Starlink-9) and two BlackSky Earth-imaging satellites from Launch Complex 39A (LC-39A) at Kennedy Space Center in Florida, on 7 August 2020, at 05:12 UTC (01:12 EDT).

SpaceX Starlink 9 launch & Falcon 9 first stage landing, 7 August 2020

Following stage separation, Falcon 9’s first stage (Block B1051) landed on the “Of Course I Still Love You” drone-ship, stationed in the Atlantic Ocean.

Falcon 9’s first stage landed on the “Of Course I Still Love You” drone-ship

Falcon 9’s first stage previously supported Crew Dragon’s first demonstration mission to the International Space Station, launch of the RADARSAT Constellation Mission, and the fourth and seventh Starlink missions.

Starlink Satellite Constellation

A SpaceX Falcon 9 rocket launches the tenth batch of approximately 60 satellites for SpaceX’s Starlink broadband network, a mission designated Starlink 9. Two Earth observation microsatellites for BlackSky Global, a Seattle-based company, will launch as rideshare payloads on this mission. Moved forward from June 24. Delayed from June 23, June 25 and June 26. Scrubbed on July 8 due to poor weather. Scrubbed on July 11 due to technical issue. Delayed from July 29, July 31, Aug. 1 and Aug. 6.

For more information about SpaceX, visit:

Images, Video, Text, Credits: SpaceX/SciNews/ Aerospace/Roland Berga.


vendredi 7 août 2020

Space Station Science Highlights: Week of August 3, 2020

ISS - Expedition 63 Mission patch.

Aug. 7, 2020

The week of August 3, crew members aboard the International Space Station conducted scientific research on water recovery systems, complex plasmas, and the physics of wet foams. 

Image above: Hurricane Hanna is seen approaching the southern coast of Texas in this image taken from the International Space Station. Image Credit: NASA.

Now in its 20th year of continuous human presence, the space station provides a platform for long-duration research in microgravity and for learning to live and work in space. NASA’s Commercial Crew Program, once again launching astronauts on American rockets and spacecraft from American soil, increases the crew time available for science on the orbiting lab.

Here are details on some of the microgravity investigations currently taking place:

Toward better water recovery systems

Image above: NASA astronaut Chris Cassidy works on the Droplet Formation Study. The investigation observes how microgravity shapes water droplets and could improve water conservation and water pressure techniques on Earth. Image Credit: NASA.

Crew members replaced a pump for the Japanese Experiment Module (JEM) Water Recovery System (JWRS), a demonstration from the Japan Aerospace Exploration Agency (JAXA) of a way to generate drinkable water from urine as part of the Environmental Control and Life Support System (ECLSS). On future long-term missions, adequate water supply could be a limiting factor. Currently, crews collect and store urine and waste water or vent them overboard. Future water recovery systems on spacecraft or habitations on the Moon or Mars will need to be smaller, recover more water, and use less power than conventional systems.

Investigating complex plasmas

During the week, crew members configured video monitors for Plasma Kristall-4 (PK-4), a scientific collaboration between the ESA (European Space Agency) and the Russian Federal Space Agency (Roscosmos). PK-4 studies complex plasmas, which are low-temperature gaseous mixtures of ionized gas, neutral gas, and micron-sized particles. The particles become highly charged and interact strongly, potentially leading to self-organized structures called plasma crystals. The investigation examines transport properties, thermodynamics, kinetics and statistical physics, dynamical processes, and instabilities in these complex plasmas. Understanding how plasma crystals form in microgravity could shed light on plasma phenomena in space and lead to new research methods and improved spacecraft designs.

Finding properties of foams

Image above: This image shows a run from the FOAM investigation, which studies bubble size, rearrangement dynamics, and other properties of wet foams.
Image Credit: NASA.

Fluid Science Laboratory (FSL) Soft Matter Dynamics - Hydrodynamics of Wet Foams (FOAM), an investigation from the ESA, studies bubble size, rearrangement dynamics, and other properties of wet foams. Solid and liquid foams are used across a variety of industries, from cleaning products to food and medicines, cleaning oil from water, and more. Foams break down quickly in gravity, though, making them difficult to study on Earth. Gaining a better fundamental understanding of foams could help improve their control and process design in industry. During the week, the crew installed sample cell units in preparation for experiment runs.

Other investigations on which the crew performed work:

- Droplet Formation Study evaluates the size and speed of water droplets from Delta Faucet’s H2Okinetic shower head. Gravity’s full effects on formation of water droplet size are unknown, and this research could help improve the technology to conserve water and energy.

- Plant Habitat-02 examines conditions such as intensity and spectral composition of light and the effects of the culture medium or soil in cultivation of radishes. This model plant is nutritious, has a short cultivation time and is genetically similar to Arabidopsis, a plant frequently studied in microgravity.

- Radi-N2, a Canadian Space Agency investigation, uses bubble detectors to better characterize the neutron environment on the space station, which could help define the risk this radiation source poses to crew members and provide data necessary to develop advanced protective measures for future spaceflight.

- Astrobee tests three self-contained, free-flying robots designed to assist astronauts with routine chores, give ground controllers additional eyes and ears, and perform crew monitoring, sampling, and logistics management.

- The Integrated Impact of Diet on Human Immune Response, the Gut Microbiota, and Nutritional Status During Adaptation to Spaceflight (Food Physiology) investigation documents the effects of dietary improvements on immune function and the gut microbiome and the ability of those improvements to support adaptation to spaceflight.

Space to Ground: Gulf Coast Splashdown: 08/07/2020

Related links:

Expedition 63:

Commercial Crew Program:


Plasma Kristall-4 (PK-4):


ISS National Lab:

Spot the Station:

Space Station Research and Technology:

International Space Station (ISS):

Images (mentioned), Video (NASA), Text, Credits: NASA/Michael Johnson/John Love, ISS Research Planning Integration Scientist Expedition 63.

Best regards,

Hubble Sees Near and Far

NASA - Hubble Space Telescope patch.

Aug. 7, 2020

The barred spiral galaxy known as NGC 4907 shows its starry face from 270 million light-years away to anyone who can see it from the Northern Hemisphere. This is a new image from the NASA/ESA Hubble Space Telescope of the face-on galaxy, displaying its beautiful spiral arms, wound loosely around its central bright bar of stars.

Shining brightly below the galaxy is a star that is actually within our own Milky Way galaxy. This star appears much brighter than the billions of stars in NGC 4907 as it is 100,000 times closer, residing only 2,500 light-years away.

NGC 4907 is also part of the Coma Cluster, a group of over 1,000 galaxies, some of which can be seen around NGC 4907 in this image. This massive cluster of galaxies lies within the constellation of Coma Berenices, which is named for the locks of Queen Berenice II of Egypt: the only constellation named after a historical person.

Hubble Space Telescope (HST)

For more information about Hubble, visit:

Text Credits: ESA (European Space Agency)/NASA/Rob Garner/Image, Animation Credits: ESA/Hubble & NASA, M. Gregg.


Cluster’s 20 years of studying Earth’s magnetosphere

ESA - Cluster Mission logo.

August 7, 2020

Despite a nominal lifetime of two years, ESA’s Cluster is now entering its third decade in space. This unique four-spacecraft mission has been revealing the secrets of Earth’s magnetic environment since 2000 and, with 20 years of observations under its belt, is still enabling new discoveries as it explores our planet’s relationship with the Sun.


As the only planet known to host life, Earth occupies a truly unique place in the Solar System. The Cluster mission, launched in the summer of 2000, was designed and built to study perhaps the one main thing that makes Earth a unique habitable world where life can thrive. This one life-enabling thing is Earth’s powerful magnetosphere, which protects the planet from the bombardment by cosmic particles but also interacts with them, creating spectacular phenomena, such as polar lights.

Earth’s magnetosphere, a tear drop-shaped region that begins some 65,000 kilometres away from the planet on the day side and extends up to 6,300,000 kilometers on the night side, is a result of the interaction between the planet’s magnetic field, generated by the motions of its molten metal core, and the solar wind. Cluster is the first mission to have studied, modelled and three-dimensionally mapped this region and the processes within it in detail. By doing so, it helped to advance our understanding of space weather phenomena, which arise from the interplay between the magnetosphere and the energetic particles forming the solar wind. These phenomena can damage not only living organisms, but also electronic equipment, whether on the ground or in orbit.

Rumba, Salsa, Samba and Tango

Earth’s bow shock and magnetosphere

The Cluster mission comprises four spacecraft flying in a pyramid-like formation on an elliptical polar orbit. The four spacecraft, called Rumba, Salsa, Samba and Tango, each carrying the same payload of 11 advanced instruments, were dispatched to orbit with two rocket launches on 16 July and 9 August 2000.

Although the mission has become an enormous success, having enabled numerous scientific breakthroughs, it’s early days didn’t go off without a hitch. An under-performance of the first stage of the Soyuz launcher left Rumba and Tango in an incorrect orbit, forcing them to rely on their own propulsion, as well as the Fregat upper stage of Soyuz, to get to the right position to join Salsa and Samba. The mishap followed the failed launch of the original Cluster I quartet in 1996.

“ESA was a bit worried 20 years ago, during the launch of the second pair of spacecraft,” admits Philippe Escoubet, Cluster Project Scientist at ESA “Ever since then, the mission has made huge progress, and it is far from finished.”

Over the past two decades, Cluster observations have uncovered details about the processes in the magnetosphere, revealed how the atmosphere supports life, and provided essential insights into space weather needed to enable safe satellite communications and space or air travel.

A unique architecture

The key to the mission’s power is not just its four-spacecraft configuration but also the fact that operators can adjust the distance between the four satellites from 3 up to 60 000 kilometres depending on the scientific objective.

“This multi-spacecraft design is key to Cluster’s success,” explains Philippe. “By using four spacecraft instead of one, Cluster is able to uniquely measure multiple areas of space – and gain multiple perspectives on a particular event or activity, such as a solar storm – simultaneously.”

When closer together, the Cluster spacecraft can dig into the finer magnetic structures in near-Earth space; when more separated, they can obtain a broader view of wider-scale activity. Across its orbit, Cluster flies both within and outside of Earth’s magnetosphere, allowing it to investigate the phenomena on both sides of our planet’s magnetic shield.

Polar power

Cluster and Image during aurora observation

While most missions exploring Earth’s magnetic phenomena focus on the equator where many electric currents flow, the Cluster quartet circles the Earth in a polar orbit, which allows it to pass periodically above both Earth’s poles. The polar regions are magnetically extremely dynamic. Solar wind in this area can penetrate deeper into Earth’s upper atmosphere through the polar cusps, funnel-like openings in the magnetosphere above the poles, giving rise to the spectacular auroras.

Cluster’s ability to observe higher latitudes than other missions made the mission a key player in forming a global magnetospheric map.

One element of this was accurately mapping the position and extent of so-called cold plasma (slow-moving charged particles) around Earth in three dimensions. Such plasma – which Cluster found to, surprisingly, dominate the magnetosphere’s volume up to 70% of the time – is thought to play a key role in how stormy space weather affects our planet. Cluster has also studied how the inner parts of Earth’s magnetosphere work to replenish other parts with fresh plasma, observing not only sporadic plumes that push plasma outwards, but also a steady atmospheric leak of almost 90 thousand kilograms of material per day.

20 years of discovery


Through its mapping of Earth’s magnetic field, and comparison of this to Mars’ lacklustre present-day magnetism, Cluster has reaffirmed the importance of our magnetosphere in shielding us from the solar wind.

Cluster has revealed more about the dynamics within the magnetotail, the part of the magnetosphere extending ‘behind’ our planet away from the Sun. The mission identified that the magnetic field in this region oscillates in amplitude due to internal ‘kink-like’ waves, and solved a long-standing mystery by determining that the phenomenon of ‘equatorial noise’ (noisy plasma waves found near the equatorial plane of Earth’s magnetic field) is generated by protons.

By investigating the spatial characteristics of the outer region of the magnetosphere, Cluster has brought a deeper understanding of how solar wind particles can penetrate our magnetic ‘shield’. The solar wind is a stream of charged particles flooding out into space from the Sun, moving at speeds of up to 2000 kilometres per hour. Cluster identified tiny swirls of turbulence that affect how energy (heat) is distributed throughout this wind, and discovered that, while it protects us from incoming particles, our magnetosphere is quite porous and sieve-like, allowing super-heated solar wind particles to drill through.

By collaborating with other missions, Cluster has helped reveal the workings of high-latitude ‘theta’ auroras and less familiar ‘black auroras’, enabling a detailed understanding of how different regions of space exchange particles. The mission also discovered the origin of so-called ‘killer electrons’, energetic particles in Earth’s outer belt of radiation that can cause havoc for satellites, by observing this process first-hand. Cluster found these electrons to arise as solar storm-related shock waves compress Earth’s magnetic field lines, resulting in these lines vibrating and accelerating electrons to high, and dangerous, speeds.

Cluster has investigated the dynamics of a process known as magnetic reconnection, providing the first in situ observations of magnetic field lines breaking and reforming – a finding that required multiple simultaneous observations, as only Cluster could provide at the time. Cluster data also showed that energy is released in unexpected ways during reconnection events, helping scientists to build a fuller understanding of plasma dynamics.

Space weather and geomagnetic storms, phenomena driven by Earth’s relationship with the Sun, have been a topic of focus for Cluster. The mission has modelled Earth’s magnetic field at both low and high altitudes, and identified the complex dynamics at play in the solar wind itself, with the goal of enabling more informed and accurate ‘space weather forecasting’. Late last year, by analysing Cluster’s comprehensive Science Archive, scientists were also able to release the eerie ‘song’ emitted by Earth when it is hit by a solar storm, created by magnetic field waves.

A treasure trove of data

Across its many years of operation, Cluster has amassed an unprecedented repository of data about Earth’s environment. In fact, by drawing on 18 years of this data, scientists recently found that iron is widely, and surprisingly, distributed throughout our planet’s vicinity, demonstrating the enduring power of Cluster in facilitating novel scientific discovery.

“Having such a long baseline of data has enabled a number of truly ground-breaking findings,” adds Arnaud Masson, Deputy Project Scientist for the Cluster mission at ESA. “By continually monitoring and recording the dynamics and properties of Earth’s magnetosphere over two decades, Cluster has created brand new opportunities for scientists to spot new or longer-term trends on differing spatial and temporal scales.”

Cluster, along with other ESA spacecraft, is also paving the way for forthcoming missions such as the European-Chinese Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE), which is scheduled for launch in 2023. SMILE will dig deeper into the Sun-Earth connection, and will build upon the remarkable work of Cluster to reveal even more about the complex and intriguing magnetic environment surrounding our planet.

“For two decades now, Cluster has been an exciting and truly cutting-edge mission, sending back all manner of new information about the Universe around us,” says Philippe. “Thanks to its unique design, long lifetime, and advanced capabilities, Cluster has unlocked a wealth of secrets about the environment around Earth. Cluster is still going strong, and will continue to help us characterise the phenomena we see around us for – hopefully! – years to come.”

Further information:

Cluster science archive:

Related links:


European-Chinese Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE):

Images, Text, Credits: ESA/CC BY-SA 3.0 IGO/AOES Medialab/NASA/SOHO/LASCO/EIT/C. Gauna.


jeudi 6 août 2020

Station Crew Works Japanese and Russian Research

ISS - Expedition 63 Mission patch.

August 6, 2020

Advanced space science, cargo transfers and orbital maintenance kept the three Expedition 63 crew members occupied Thursday aboard the International Space Station.

Commander Chris Cassidy spent a good portion of his day working inside JAXA’s (Japan Aerospace Exploration Agency) Kibo laboratory module. The experienced shuttle and station astronaut retrieved the Handhold Experiment Platform-2 (HXP-2), packed with several experiments, from inside Kibo’s airlock.

Image above: Russia’s Progress 76 resupply ship is pictured docked to the International Space Station’s Pirs docking compartment. Below the orbiting lab are the city lights of southeastern Europe. Image Credit: NASA.

The HXP-2 was grappled by Japan’s robotic arm, removed from Kibo’s Exposed Facility and placed inside the airlock last week. The small research platform housed a variety of experiment samples exposed to the vacuum of space for observation.

Russia’s newest resupply ship, the Progress 76 (76P) which delivered nearly three tons of food, fuel and supplies last month, continued to be offloaded today. Cosmonauts Anatoly Ivanishin and Ivan Vagner unpacked electronics gear from the 76P and updated the space station’s inventory system.

A Starry Sky Above the Earth's Atmospheric Glow

Image above: This long-exposure photograph captures a starry sky above the Earth's atmospheric glow as the International Space Station orbited above the Indian Ocean about halfway between South Africa and Australia. Image Credit: NASA.

Ivanishin then moved on to science exploring how bone marrow and enzymes adapt to weightlessness and studied Earth’s upper atmosphere. Vagner checked station smoke detectors and transferred waste fluids into the Progress 75 cargo craft.

Related links:

Expedition 63:

Kibo laboratory module:

Exposed Facility:

Bone marrow and enzymes:

Earth’s upper atmosphere:

Space Station Research and Technology:

International Space Station (ISS):

Images (mentioned), Text, Credits: NASA/Mark Garcia/Yvette Smith.

Best regards,

NASA’s MAVEN Observes Martian Night Sky Pulsing in Ultraviolet Light

NASA - MAVEN Mission patch.

Aug. 6, 2020

Vast areas of the Martian night sky pulse in ultraviolet light, according to images from NASA’s MAVEN spacecraft. The results are being used to illuminate complex circulation patterns in the Martian atmosphere.

Mars Nightglow Animation from MAVEN Observations

Video above: Mars’ nightside atmosphere glows and pulsates in this data animation from MAVEN spacecraft observations. Green-to-white false color shows the enhanced brightenings on Mars’ ultraviolet “nightglow" measured by MAVEN’s Imaging UltraViolet Spectrograph at about 70 kilometers (approximately 40 miles) altitude. A simulated view of the Mars globe is added digitally for context, with ice caps visible at the poles. Three nightglow brightenings occur over one Mars rotation, the first much brighter than the other two. All three brightenings occur shortly after sunset, appearing on the left of this view of the night side of the planet. The pulsations are caused by downwards winds which enhance the chemical reaction creating nitric oxide which causes the glow. Months of data were averaged to identify these patterns, indicating they repeat nightly. Video Credits: NASA/MAVEN/Goddard Space Flight Center/CU/LASP.

The MAVEN team was surprised to find that the atmosphere pulsed exactly three times per night, and only during Mars’ spring and fall. The new data also revealed unexpected waves and spirals over the winter poles, while also confirming the Mars Express spacecraft results that this nightglow was brightest over the winter polar regions.

Image above: This is an image of the ultraviolet “nightglow” in the Martian atmosphere. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The nightglow was measured at about 70 kilometers (approximately 40 miles) altitude by the Imaging UltraViolet Spectrograph instrument on NASA’s MAVEN spacecraft. A simulated view of the Mars globe is added digitally for context. The image shows an intense brightening in Mars’ nightside atmosphere. The brightenings occur regularly after sunset on Martian evenings during fall and winter seasons, and fade by midnight. The brightening is caused by increased downwards winds which enhance the chemical reaction creating nitric oxide which causes the glow. Image Credits: NASA/MAVEN/Goddard Space Flight Center/CU/LASP.

“MAVEN’s images offer our first global insights into atmospheric motions in Mars’ middle atmosphere, a critical region where air currents carry gases between the lowest and highest layers,” said Nick Schneider of the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP), Boulder, Colorado. The brightenings occur where vertical winds carry gases down to regions of higher density, speeding up the chemical reactions that create nitric oxide and power the ultraviolet glow. Schneider is instrument lead for the MAVEN Imaging Ultraviolet Spectrograph (IUVS) instrument that made these observations, and lead author of a paper on this research appearing August 6 in the Journal of Geophysical Research, Space Physics. Ultraviolet light is invisible to the human eye but detectable by specialized instruments.

Image above: The diagram explains the cause of Mars’ glowing nightside atmosphere. On Mars’ dayside, molecules are torn apart by energetic solar photons. Global circulation patterns carry the atomic fragments to the nightside, where downward winds increase the reaction rate for the atoms to reform molecules. The downwards winds occur near the poles at some seasons and in the equatorial regions at others. The new molecules hold extra energy which they emit as ultraviolet light. Image Credits: NASA/MAVEN/Goddard Space Flight Center/CU/LASP.

“The ultraviolet glow comes mostly from an altitude of about 70 kilometers (approximately 40 miles), with the brightest spot about a thousand kilometers (approximately 600 miles) across, and is as bright in the ultraviolet as Earth’s northern lights,” said Zac Milby, also of LASP. “Unfortunately, the composition of Mars’ atmosphere means that these bright spots emit no light at visible wavelengths that would allow them to be seen by future Mars astronauts. Too bad: the bright patches would intensify overhead every night after sunset, and drift across the sky at 300 kilometers per hour (about 180 miles per hour).”

The pulsations reveal the importance of planet-encircling waves in the Mars atmosphere. The number of waves and their speed indicates that Mars’ middle atmosphere is influenced by the daily pattern of solar heating and disturbances from the topography of Mars’ huge volcanic mountains. These pulsating spots are the clearest evidence that the middle atmosphere waves match those known to dominate the layers above and below.

“MAVEN’s main discoveries of atmosphere loss and climate change show the importance of these vast circulation patterns that transport atmospheric gases around the globe and from the surface to the edge of space.” said Sonal Jain, also of LASP.

Image above: This is an image of the ultraviolet “nightglow” in the Martian atmosphere over the south pole. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The nightglow was measured at about 70 kilometers (approximately 40 miles) altitude by the Imaging UltraViolet Spectrograph instrument on NASA’s MAVEN spacecraft. A simulated view of the Mars globe is added digitally for context, and the faint white area in the center of the image is the polar ice cap. The image shows an unexpectedly bright glowing spiral in Mars’ nightside atmosphere. The cause of the spiral pattern is unknown. Image Credits: NASA/MAVEN/Goddard Space Flight Center/CU/LASP.

Next, the team plans to look at nightglow “sideways”, instead of down from above, using data taken by IUVS looking just above the edge of the planet. This new perspective will be used to understand the vertical winds and seasonal changes even more accurately.

MAVEN (Mars Atmosphere and Volatile Evolution). Animation Credit: NASA

The Martian nightglow was first observed by the SPICAM instrument on the European Space Agency’s Mars Express spacecraft. However, IUVS is a next-generation instrument better able to repeatedly map out the nightside glow, finding patterns and periodic behaviors. Many planets including Earth have nightglow, but MAVEN is the first mission to collect so many images of another planet’s nightglow.

The research was funded by the MAVEN mission. MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics, Boulder, and NASA Goddard manages the MAVEN project. NASA is exploring our Solar System and beyond, uncovering worlds, stars, and cosmic mysteries near and far with our powerful fleet of space and ground-based missions.

Related link:

MAVEN (Mars Atmosphere and Volatile Evolution):

Video (mentioned), Images (mentioned), Animation (mentioned), Text, Credits: NASA/GSFC/Bill Steigerwald/Nancy Jones.


NASA’s OSIRIS-REx is One Rehearsal Away from Touching Asteroid Bennu

NASA - OSIRIS-REx Mission patch.

Aug. 6, 2020

NASA’s first asteroid sampling spacecraft is making final preparations to grab a sample from asteroid Bennu’s surface. Next week, the OSIRIS-REx mission will conduct a second rehearsal of its touchdown sequence, practicing the sample collection activities one last time before touching down on Bennu this fall.

On Aug. 11, the mission will perform its “Matchpoint” rehearsal – the second practice run of the Touch-and-Go (TAG) sample collection event. The rehearsal will be similar to the Apr. 14 “Checkpoint” rehearsal, which practiced the first two maneuvers of the descent, but this time the spacecraft will add a third maneuver, called the Matchpoint burn, and fly even closer to sample site Nightingale – reaching an altitude of approximately 131 ft (40 m) – before backing away from the asteroid.

Image above: This artist’s concept shows the trajectory and configuration of NASA’s OSIRIS-REx spacecraft during Matchpoint rehearsal, which is the final time the mission will practice the initial steps of the sample collection sequence before touching down on asteroid Bennu. Image Credits: NASA/Goddard/University of Arizona.

This second rehearsal will be the first time the spacecraft executes the Matchpoint maneuver to then fly in tandem with Bennu’s rotation. The rehearsal also gives the team a chance to become more familiar navigating the spacecraft through all of the descent maneuvers, while verifying that the spacecraft’s imaging, navigation and ranging systems operate as expected during the event.

During the descent, the spacecraft fires its thrusters three separate times to make its way down to the asteroid’s surface. The spacecraft will travel at an average speed of around 0.2 mph (0.3 kph) during the approximately four-hour excursion. Matchpoint rehearsal begins with OSIRIS-REx firing its thrusters to leave its 0.5-mile (870-m) safe-home orbit. The spacecraft then extends its robotic sampling arm – the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded, parked position out to the sample collection configuration. Immediately following, the spacecraft rotates to begin collecting navigation images for the Natural Feature Tracking (NFT) guidance system. NFT allows OSIRIS-REx to autonomously navigate to Bennu’s surface by comparing an onboard image catalog with the real-time navigation images taken during descent. As the spacecraft approaches the surface, the NFT system updates the spacecraft’s predicted point of contact depending on OSIRIS-REx’s position in relation to Bennu’s landmarks.

The spacecraft’s two solar panels then move into a “Y-wing” configuration that safely positions them up and away from the asteroid’s surface. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface during the sample collection event.

When OSIRIS-REx reaches an altitude of approximately 410 ft (125 m), it performs the Checkpoint burn and descends more steeply toward Bennu’s surface for another eight minutes. At approximately 164 ft (50 m) above the asteroid, the spacecraft fires its thrusters a third time for the Matchpoint burn. This maneuver slows the spacecraft’s rate of descent and adjusts its trajectory to match Bennu’s rotation as the spacecraft makes final corrections to target the touchdown spot. OSIRIS-REx will continue capturing images of Bennu’s landmarks for the NFT system to update the spacecraft’s trajectory for another three minutes of descent. This brings OSIRIS-REx to its targeted destination around 131 ft (40 m) from Bennu – the closest it has ever been to the asteroid. With the rehearsal complete, the spacecraft executes a back-away burn, returns its solar panels to their original position and reconfigures the TAGSAM arm back to the parked position.

During the rehearsal, the one-way light time for signals to travel between Earth and the spacecraft will be approximately 16 minutes, which prevents the live commanding of flight activities from the ground. So prior to the rehearsal’s start, the OSIRIS-REx team will uplink all of the event’s commands to the spacecraft, allowing OSIRIS-REx to perform the rehearsal sequence autonomously after the GO command is given. Also during the event, the spacecraft’s low gain antenna will be its only antenna pointing toward Earth, transmitting data at the very slow rate of 40 bits per second. So while the OSIRIS-REx team will be able to monitor the spacecraft’s vital signs, the images and science data collected during the event won’t be downlinked until the rehearsal is complete. The team will experience these same circumstances during the actual TAG event in October.

OSIRIS-REx collecting sample

Following Matchpoint rehearsal, the OSIRIS-REx team will verify the flight system’s performance during the descent, including that the Matchpoint burn accurately adjusted the spacecraft’s descent trajectory for its touchdown on Bennu. Once the mission team determines that OSIRIS-REx operated as expected, they will command the spacecraft to return to its safe-home orbit around Bennu.

The mission team has spent the last several months preparing for the Matchpoint rehearsal while maximizing remote work as part of its COVID-19 response. On the day of rehearsal, a limited number of personnel will monitor the spacecraft from Lockheed Martin Space’s facility, taking appropriate safety precautions, while the rest of the team performs their roles remotely. The mission implemented a similar protocol during the Checkpoint rehearsal in April.

On Oct. 20, the spacecraft will travel all the way to the asteroid’s surface during its first sample collection attempt. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for approximately five seconds, fire a charge of pressurized nitrogen to disturb the surface and collect a sample before the spacecraft backs away. The spacecraft is scheduled to return the sample to Earth on Sept. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Related link:

OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security Regolith Explorer):

Image (mentioned), Animation, Text, Credits: NASA/Karl Hille/University of Arizona, by Brittany Enos.

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Hubble Makes the First Observation of a Total Lunar Eclipse By a Space Telescope

ESA - Hubble Space Telescope logo.

6 August 2020

Hubble Observes the Total Lunar Eclipse (Artist’s Impression)

Taking advantage of a total lunar eclipse, astronomers using the NASA/ESA Hubble Space Telescope have detected ozone in Earth’s atmosphere. This method serves as a proxy for how they will observe Earth-like planets around other stars in the search for life. This is the first time a total lunar eclipse was captured from a space telescope and the first time such an eclipse has been studied in ultraviolet wavelengths.

To prepare for exoplanet research with bigger telescopes that are currently in development, astronomers decided to conduct experiments much closer to home, on the only known inhabited terrestrial planet: Earth. Our planet’s perfect alignment with the Sun and Moon during a total lunar eclipse mimics the geometry of a transiting terrestrial planet with its star. In a new study, Hubble did not look at Earth directly. Instead, astronomers used the Moon as a mirror that reflects the sunlight that has been filtered through Earth’s atmosphere. Using a space telescope for eclipse observations is cleaner than ground-based studies because the data is not contaminated by looking through Earth’s atmosphere.

Lunar Eclipse

These observations were particularly challenging because just before the eclipse the Moon is very bright, and its surface is not a perfect reflector since it’s mottled with bright and dark areas. Furthermore, the Moon is so close to Earth that Hubble had to try and keep a steady eye on one select region, to precisely track the Moon’s motion relative to the space observatory. It is for these reasons that Hubble is very rarely pointed at the Moon.

The measurements detected the strong spectral fingerprint of ozone, a key prerequisite for the presence – and possible evolution – of life as we know it in an exo-Earth. Although some ozone signatures had been detected in previous ground-based observations during lunar eclipses, Hubble’s study represents the strongest detection of the molecule to date because it can look at the ultraviolet light, which is absorbed by our atmosphere and does not reach the ground. On Earth, photosynthesis over billions of years is responsible for our planet’s high oxygen levels and thick ozone layer. Only 600 million years ago Earth’s atmosphere had built up enough ozone to shield life from the Sun’s lethal ultraviolet radiation. That made it safe for the first land-based life to migrate out of our oceans.

Hubble’s Region of Study During the Lunar Eclipse

“Finding ozone in the spectrum of an exo-Earth would be significant because it is a photochemical byproduct of molecular oxygen, which is a byproduct of life,” explained Allison Youngblood of the Laboratory for Atmospheric and Space Physics in Colorado, USA, lead researcher of Hubble’s observations.

Hubble recorded ozone’s ultraviolet spectral signature imprinted on sunlight that filtered through Earth’s atmosphere during a lunar eclipse that occurred on 20-21 January, 2019. Several other telescopes also made spectroscopic observations at other wavelengths during the eclipse, searching for more of Earth’s life-nurturing ingredients, such as oxygen, methane, water, and carbon monoxide.

Hubble Observes the Total Lunar Eclipse (Artist’s Impression)

“To fully characterize exoplanets, we will ideally use a variety of techniques and wavelengths,” explained team member Antonio Garcia Munoz of the Technische Universität Berlin in Germany. ”This investigation clearly highlights the benefits of the ultraviolet spectroscopy in the characterization of exoplanets. It also demonstrates the importance of testing innovative ideas and methodologies with the only habitable planet that we know of to date!”

The atmospheres of some exoplanets can be probed when the alien world passes across the face of its parent star, during a so-called transit. During a transit, starlight filters through the backlit exoplanet’s atmosphere. If viewed close up, the planet’s silhouette would look like it had a thin, glowing “halo” around it caused by the illuminated atmosphere, just as Earth does when seen from space.

Hubble Observes the Total Lunar Eclipse (Artist’s Impression)

Chemicals in the atmosphere leave their telltale signature by filtering out certain colors of starlight. The spectroscopy of transiting planets' atmospheres was pioneered by Hubble astronomers. This was especially innovative because extrasolar planets had not yet been discovered when Hubble was launched in 1990. Therefore, the space observatory was not initially designed for such experiments. So far, astronomers have used Hubble to observe the atmospheres of gas giant planets that transit their stars. But terrestrial planets are much smaller objects and their atmosphere thinner. Therefore, analyzing these signatures is much harder.

That’s why researchers will need space telescopes much larger than Hubble to collect the feeble starlight passing through these small planets’ atmospheres during a transit. These telescopes will need to observe planets for a longer period, many dozens of hours, to build up a strong signal. For Youngblood’s study, Hubble spent five hours collecting data throughout the various phases of the lunar eclipse.

Finding ozone in the skies of a terrestrial extrasolar planet does not guarantee that life exists on the surface. “You would need other spectral signatures in addition to ozone to conclude that there was life on the planet, and these signatures cannot be seen in ultraviolet light,” Youngblood said.

Hubble Space Telescope (HST)

Astronomers must search for a combination of biosignatures, such as ozone and methane, when exploring the possibilities of life. A multiwavelength campaign is needed because many biosignatures—ozone, for example—are more easily detected at specific wavelengths. Astronomers searching for ozone also must consider that it builds up over time as a planet evolves. About 2 billion years ago on Earth, the ozone was a fraction of what it is now.

The upcoming NASA/ESA/CSA James Webb Space Telescope, an infrared observatory scheduled to launch in 2021, will be able to penetrate deep into a planet’s atmosphere to detect methane and oxygen.

“We expect JWST to push the technique of transmission spectroscopy of exoplanet atmospheres to unprecedented limits,” added Garcia Munoz. “In particular, it will have the capacity to detect methane and oxygen in the atmospheres of planets orbiting nearby, small-sized stars. This will open the field of atmospheric characterization to increasingly smaller exoplanets.”


[1] This study’s paper will appear in the Astronomical Journal:


Hubblecast 130 Light: Hubble Studies the Earth during a Total Lunar Eclipse

Hubblecast 121: What can we learn from exoplanet transits?

Images of Hubble:

HubbleSite release:

Science paper:

Link to Space Scoop:

ESA Hubblesite:

Images, Video, Text, Credits: ESA/NASA/Hubble/Bethany Downer/Technische Universität Berlin/Antonio Garcia Munoz/Laboratory for Atmospheric and Space Physics Boulder/Allison Youngblood/ESA/Hubble, M. Kornmesser.


CASC - Long March-2D launches Gaofen-9 04

CASC - China Aerospace Science and Technology Corporation logo.

August 6, 2020

Long March-2D launches Gaofen-9 04

A Long March-2D launch vehicle launched the Gaofen-9 04 satellite from the Jiuquan Satellite Launch Center, Gansu Province, northwest China, on 6 August 2020, at 04:01 UTC (12:01 local time).

Long March-2D launches Gaofen-9 04

Gaofen-9 04 is a new optical remote-sensing satellite with a resolution up to the sub-meter level.

Gaofen satellite

According to official sources, the satellite entered the planned orbit and will be mainly used for land surveys, crop yield estimation, disaster prevention and mitigation.

Related articles:

CASC - Long March-2D launches Gaofen-9 03 and HEAD-5 satellites

CASC - Long March-2D launches Gaofen-9 02 and HEAD-4 satellites

For more information about China Aerospace Science and Technology Corporation (CASC):

Images, Video, Text, Credits: Credits: China Central Television (CCTV)/China Aerospace Science and Technology Corporation (CASC)/SciNews/Günter Space Page/ Aerospace/Roland Berga.


ExoMars captures spring in martian craters

ESA & ROSCOSMOS - ExoMars Mission patch.

August 6, 2020

ExoMars Trace Gas Orbiter (TGO)

A new set of images captured this spring by the Colour and Stereo Surface Imaging System (CaSSIS) on the ESA-Roscosmos ExoMars Trace Gas Orbiter shows a series of interesting geological features on the surface of Mars, captured just as the planet passed its spring equinox.

Dune fields in the Green Crater of Mars

Dune fields in Mars' Green Crater

The image above, taken on 27 April 2020 and centred at 52.3°S, 351.8°E, shows part of an impact crater located inside the larger Green Crater in the Argyre quadrangle in the southern hemisphere of Mars.

The image reveals an almost black dune field on the right surrounded by red soils, partially covered with bright white ice. Gullies, also partially covered with ice, are visible in the crater wall in the centre of the image. Scientists are currently investigating the relationship between this seasonal ice and the presence of the gullies. The image was taken just after the spring equinox in the southern hemisphere of Mars, when the southernmost part of the crater (to the right) was almost completely free of ice while the northern part (centre) was still partially covered. The southern crater wall has had a longer exposure to the Sun (like on Earth, equator-facing slopes receive more sunlight), so the ice in this area has receded faster.

Leaf-like structures in Antoniadi impact crater

Leaf-like structures in Antoniadi impact crater

This image, captured on 25 March 2020, shows the bottom of the 400 km in diameter Antoniadi impact crater, which is located in the northern hemisphere of Mars in the Syrtis Major Planum region. The blue colour of the image, centred at 21.0°N, 61.2°E, does not represent the real colour of the crater floor but highlights the diversity of the rock composition inside this impact crater.

In the centre of the image are dendritic structures which look like the veins on oak leaves. These structures, evidence of ancient river networks in this region, protrude from the surface, unlike channels, which are usually sunken in the surface. This is because the channels were filled with harder material – possibly lava – and over time the softer rocks surrounding these branching channels have been eroded, leaving an inverted imprint of this ancient river system.

Argyre impact basin after spring equinox

Argyre impact basin after spring equinox

This image of the Argyre impact basin in the southern highlands of Mars was taken on 28 April 2020 just as Mars had passed its southern hemisphere spring equinox. The seasonal ice in the 800km-long impact basin is visibly receding while the ridge on the right side of the image is still covered with frost. The image is centred at 57.5°S, 310.2°E. The frost-covered ridge is facing the pole, therefore receiving less solar radiation than the neighbouring equator-facing slope. On Mars, incoming solar radiation transforms the ice into water vapour directly without melting it first into water in a process called sublimation. Since the north-facing slope (on the left) has had a longer exposure to solar radiation, its ice has sublimated more quickly.

Rock composition in Ius Chasma canyon

Rock composition in Ius Chasma canyon

The image taken on 5 May 2020 shows a part of the floor of the Ius Chasma canyon, part of the Valles Marines system of canyons that stretches nearly a quarter of the circumference of Mars south of the planet's equator. The Ius Chasma canyon, which can be seen in the image rising up to a ridge on the right side, is about 1000 km long and up to 8 km deep, which makes it more than twice as long and four times as deep as the famous Grand Canyon in the US state of Arizona. The centre of this image is located at 8.8°S, 282.5°E.

The beautiful colour variations across the floor of Ius Chasma are caused by changes in rock composition. Scientists theorise that the light rocks are salts left behind after an ancient lake evaporated. The information about the rock's composition is useful to scientists as it allows them to retrace the formation history of the canyon.

Related links:


Trace Gas Orbiter (TGO):

ExoMars/TGO operations:

Images, Text, Credits: ESA/ExoMars/CaSSIS.

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