vendredi 9 juin 2017

NASA Finds Evidence of Diverse Environments in Curiosity Samples

NASA - Mars Science Laboratory (MSL) patch.

June 9, 2017

NASA scientists have found a wide diversity of minerals in the initial samples of rocks collected by the Curiosity rover in the lowermost layers of Mount Sharp on Mars, suggesting that conditions changed in the water environments on the planet over time.

Curiosity landed near Mount Sharp in Gale Crater in August 2012. It reached the base of the mountain in 2014. Layers of rocks at the base of Mount Sharp accumulated as sediment within ancient lakes around 3.5 billion years ago. Orbital infrared spectroscopy had shown that the mountain's lowermost layers have variations in minerals that suggest changes in the area have occurred.

Image above: NASA's Curiosity Mars rover examined a mudstone outcrop area called "Pahrump Hills" on lower Mount Sharp, in 2014 and 2015. This view shows locations of some targets the rover studied there. The blue dots indicate where drilled samples of powdered rock were collected for analysis. Image Credits: NASA/JPL-Caltech/MSSS.

In a paper published recently in Earth and Planetary Science Letters, scientists in the Astromaterials Research and Exploration Science (ARES) Division at NASA's Johnson Space Center in Houston report on the first four samples collected from the lower layers of Mount Sharp.

"We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," said Elizabeth Rampe, the first author of the study and a NASA exploration mission scientist at Johnson. "These layers were deposited about 3.5 billion years ago, coinciding with a time on Earth when life was beginning to take hold. We think early Mars may have been similar to early Earth, and so these environments might have been habitable."

The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater. There is evidence for waters with different pH and variably oxidizing conditions. The minerals also show that there were multiple source regions for the rocks in "Pahrump Hills" and "Marias Pass."

The paper primarily reports on three samples from the Pahrump Hills region. This is an outcrop at the base of Mount Sharp that contains sedimentary rocks scientists believe formed in the presence of water. The other sample, called "Buckskin," was reported last year, but those data are incorporated into the paper.

Studying such rock layers can yield information about Mars' past habitability, and determining minerals found in the layers of sedimentary rock yields much data about the environment in which they formed. Data collected at Mount Sharp with the Chemistry and Mineralogy (CheMin) instrument on Curiosity showed a wide diversity of minerals.

At the base are minerals from a primitive magma source; they are rich in iron and magnesium, similar to basalts in Hawaii. Moving higher in the section, scientists saw more silica-rich minerals. In the "Telegraph Peak" sample, scientists found minerals similar to quartz. In the "Buckskin" sample, scientists found tridymite. Tridymite is found on Earth, for example, in rocks that formed from partial melting of Earth's crust or in the continental crust -- a strange finding because Mars never had plate tectonics.

In the "Confidence Hills" and "Mojave 2" samples, scientists found clay minerals, which generally form in the presence of liquid water with a near-neutral pH, and therefore could be good indicators of past environments that were conducive to life. The other mineral discovered here was jarosite, a salt that forms in acidic solutions. The jarosite finding indicates that there were acidic fluids at some point in time in this region.

Image above: This May 11, 2016, self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Okoruso" drilling site on lower Mount Sharp's "Naukluft Plateau." The scene is a mosaic of multiple images taken with the arm-mounted Mars Hands Lens Imager (MAHLI). Image Credits: NASA/JPL-Caltech/MSSS.

There are different iron-oxide minerals in the samples as well. Hematite was found near the base; only magnetite was found at the top. Hematite contains oxidized iron, whereas magnetite contains both oxidized and reduced forms of iron. The type of iron-oxide mineral present may tell scientists about the oxidation potential of the ancient waters.

The authors discuss two hypotheses to explain this mineralogical diversity. The lake waters themselves at the base were oxidizing, so either there was more oxygen in the atmosphere or other factors encouraged oxidation. Another hypothesis -- the one put forward in the paper -- is that later-stage fluids arose. After the rock sediments were deposited, some acidic, oxidizing groundwater moved into the area, leading to precipitation of the jarosite and hematite. In this scenario, the environmental conditions present in the lake and in later groundwater were quite different, but both offered liquid water and a chemical diversity that could have been exploited by microbial life.

"We have all this evidence that Mars was once really wet but now is dry and cold," Rampe said. "Today, much of the water is locked up in the poles and in the ground at high latitudes as ice. We think that the rocks Curiosity has studied reveal ancient environmental changes that occurred as Mars started to lose its atmosphere and water was lost to space."

In the paper, the authors discuss whether this specific area on Mars is a mark of this event happening or just a natural drying of this area. Scientists will search for answers to these questions as the rover moves up the mountain.

To view the paper, go to:

To learn more about ARES, go to:

For more information about the Curiosity rover mission, visit:

Images (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/Tony Greicius/JPL/Guy Webster/JSC/William P. Jeffs.


New NELIOTA project detects flashes from lunar impacts

ESA - European Space Agency patch.

June 9, 2017

Using a system developed under an ESA contract, the Greek NELIOTA project has begun to detect flashes of light caused by small pieces of rock striking the Moon's surface. NELIOTA is the first system that can determine the temperature of these impact flashes.

Studies such as NELIOTA are important because Earth and its Moon are constantly bombarded by natural space debris. Most of this material ranges in size from dust particles to small pebbles, although larger objects can appear, unexpectedly, from time to time. This was the case when an object almost 20 m in diameter disintegrated above the Russian city of Chelyabinsk in February 2013. The resultant explosion, caught on camera, caused considerable damage, although, fortunately, no one was killed.

Lunar impact flash. Credit: NELIOTA project

Particles only millimetres across usually appear several times per hour on any clear dark night in the form of meteors or 'shooting stars'. However, the number of incoming objects in the size range from decimetres to metres is not well known. Too small to be detected directly with telescopes, they are rarely captured by cameras when they enter Earth's atmosphere.

One way to determine the number of larger impactors and the potential impact threat to Earth is to observe the Moon, in particular the dark area not illuminated by the Sun. When small asteroids strike the lunar surface at high speed, they burn up on impact, generating a brief flash of light, which can be visible from Earth. Assuming a typical velocity and density, the size and mass of the object can be estimated from the brightness of the event.

A new campaign to study these lunar flashes is being undertaken by the NELIOTA (Near-Earth object Lunar Impacts and Optical TrAnsients) project, which began operation on 8 March 2017. NELIOTA utilises a refurbished telescope, which is operated by the National Observatory of Athens and located close to the Greek town of Kryoneri.

The 1.2 m telescope splits incoming light into two colours and uses two advanced digital cameras to record the data at a rate of 30 frames per second. Observations of the Moon's night hemisphere are made whenever Earth's natural satellite is above the horizon and mainly dark – between New Moon and the first quarter phase, or between last quarter and New Moon.

Kryoneri Observatory, Greece. Image Credit: Theofanis Matsopoulos

Automated software analyses the video obtained and identifies possible impact flashes. Camera effects can be excluded by identifying events that are only visible in both cameras. The cameras operate in different colour ranges, allowing the temperature of the impact flash to be estimated – NELIOTA is the first system of this type to have the potential to determine the temperature of these flashes.

The exceptional capability of the telescope was confirmed during its pre-operational, commissioning phase, when it recorded four impact flashes in about 11 hours of observing time. The task is now to observe these flashes on the dark side of the Moon over a period of 22 months.

Lunar impact flash. Credit: NELIOTA project

"Its large telescope aperture enables NELIOTA to detect fainter flashes than other lunar monitoring surveys and provides precise colour information not currently available from other projects," says Alceste Bonanos, the Principal Investigator for NELIOTA.

"Our twin camera system allows us to confirm lunar impact events with a single telescope, something that has not been done before. Once data have been collected over the 22-month long operational period, we will be able to better constrain the number of NEOs (near-Earth objects) in the decimetre to metre size range.

"The data will also help to determine the physics of impact flashes. We are analysing the flashes in collaboration with the Science Support Office of ESA, in order to measure the temperature of each flash and estimate the mass, size of the impactor and crater size created from the impact."

"These observations are very relevant for our Space Situational Awareness programme. In particular, in the size range we can observe here, the number of objects is not very well known. Performing these observations over a longer period of time will help us to better understand this number," says Detlef Koschny, co-manager of the near-Earth object segment in ESA's Space Situational Awareness programme, and a scientist in the Science Support Office.

NELIOTA is also contributing to public outreach and education.

"We are currently training two PhD students to operate the Kryoneri telescope and conduct lunar monitoring observations," says Alceste.

"We also organise public tours of Kryoneri Observatory, during which we present the NELIOTA project, as well as talks on near-Earth asteroids for students and for the general public. This year, we plan to participate in Asteroid Day 2017, by organising a public event at Kryoneri Observatory on 30 June."

Background information

The National Observatory of Athens developed and operates NELIOTA. It is funded through a contract with ESA's Science Directorate.

The NELIOTA website ( provides the observational characteristics of the flashes (time, duration, magnitude, coordinates) within 24 hours of the observations.

Following its upgrade in 2016 for the NELIOTA project, the Kryoneri telescope is mainly used for lunar monitoring. It is also contributing to follow-up photometry of transient events, such as those detected by ESA's Gaia mission, as well as asteroid occultations.

One of the dangers humans on the Moon would face is that a small asteroid could damage their infrastructure – NELIOTA will help estimate the danger from such small asteroids. As the Moon doesn't have an atmosphere, it cannot block the smaller – but still dangerous – objects. It is likely that permanent structures on the Moon will be underground, to provide better shielding from both small asteroids or meteoroids and solar radiation.

Related links:

NELIOTA website:

Kryoneri Observatory:

Science Support Office of ESA:

Space Situational Awareness programme:

Near-Earth object segment in ESA's Space Situational Awareness programme:

Asteroid Day:

Images, Text, Credits: ESA/Vicente Navarro/Detlef Koschny/National Observatory of Athens/NELIOTA project/Theofanis Matsopoulos/Alceste Bonanos.


The future of the Orion constellation

ESA - Gaia Mission patch.

9 June 2017

A new video, based on measurements by ESA’s Gaia and Hipparcos satellites, shows how our view of the Orion constellation will evolve over the next 450 000 years.

Stars are not motionless in the sky: their positions change continuously as they move through our Galaxy, the Milky Way. These motions, too slow to be appreciated with the naked eye over a human lifetime, can be captured by high-precision observations like those performed by ESA’s billion-star surveyor, Gaia.

The future of the Orion constellation

By measuring their current movements, we can reconstruct the past trajectories of stars through the Milky Way to study the origins of our Galaxy, and even estimate stellar paths millions of years into the future.

This video provides us with a glimpse over the coming 450 000 years, showing the expected evolution of a familiar patch of the sky, featuring the constellation of Orion, the Hunter.

The portion of the sky depicted in the video measures 40 x 20º – as a comparison, the diameter of the full Moon in the sky is about half a degree.

Amid a myriad of drifting stars, the shape of Orion as defined by its brightest stars is slowly rearranged into a new pattern as time goes by, revealing how constellations are ephemeral.

The red supergiant star Betelgeuse is visible at the centre towards the top of the frame at the beginning of the video (represented in a yellow–orange hue). According to its current motion, the star will move out of this field of view in about 100 000 years. The Universe has a much harsher fate in store for Betelgeuse, which is expected to explode as a supernova within the next million of years.

Gaia's all-sky view

More of the stars shown in this view will have exploded as supernovas before the end of the video, while others might be still evolving towards that end, like Orion’s blue supergiant, Rigel, visible as the bright star in the lower left, or the red giant Aldebaran, which is part of the constellation Taurus, and can be seen crossing the lower part of the frame from right to left.

Many new stars will also have been born from the Orion molecular cloud, a mixture of gas and dust that is not directly seen by Gaia – it can be identified as dark patches against the backdrop of stars – but shines brightly at infrared wavelengths. The birth and demise of stars are not shown in the video.

The Hyades cluster, a group of stars that are physically bound together and are also part of the Taurus constellation, slowly makes its way from the lower right corner to the upper left

Gaia mapping the stars of the Milky Way

The new video is based on data from the Tycho–Gaia Astrometric Solution, a resource that lists distances and motions for two million stars in common between Gaia’s first data release and the Tycho-2 Catalogue from the Hipparcos mission. Additional information from ground-based observations were included, as well as data from the Hipparcos catalogue for the brightest stars in the view.

This video provides a zoomed-in view on a specific portion of the sky. The evolution of two million stellar positions on the entire sky is shown here:

For more information about Gaia mission, visit:

Related links:

Hipparcos mission:

Gaia overview:

Gaia factsheet:

Gaia Data Release 1 Media Kit:

Frequently asked questions:

Related articles:

How many stars are there in the Universe?:

The billion-pixel camera:

Images, Video, Text, Credits: ESA/Gaia/DPAC.

Best regards,

jeudi 8 juin 2017

Hubble Astronomers Develop a New Use for a Century-Old Relativity Experiment to Measure a White Dwarf’s Mass

NASA - Hubble Space Telescope patch.

June 8, 2017

Astronomers have used the sharp vision of NASA’s Hubble Space Telescope to repeat a century-old test of Einstein’s general theory of relativity. The Hubble team measured the mass of a white dwarf, the burned-out remnant of a normal star, by seeing how much it deflects the light from a background star.

This observation represents the first time Hubble has witnessed this type of effect created by a star. The data provide a solid estimate of the white dwarf’s mass and yield insights into theories of the structure and composition of the burned-out star.

Image above: Looks can be deceiving. In this Hubble Space Telescope image, the white dwarf star Stein 2051B and the smaller star below it appear to be close neighbors. The stars, however, reside far away from each other. Stein 2051B is 17 light-years from Earth; the other star is about 5,000 light-years away. Stein 2051B is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein. Image Credits: NASA, ESA, and K. Sahu (STScI).

First proposed in 1915, Einstein’s general relativity theory describes how massive objects warp space, which we feel as gravity. The theory was experimentally verified four years later when a team led by British astronomer Sir Arthur Eddington measured how much the sun’s gravity deflected the image of a background star as its light grazed the sun during a solar eclipse, an effect called gravitational microlensing.

Astronomers can use this effect to see magnified images of distant galaxies or, at closer range, to measure tiny shifts in a star’s apparent position on the sky. Researchers had to wait a century, however, to build telescopes powerful enough to detect this gravitational warping phenomenon caused by a star outside our solar system. The amount of deflection is so small only the sharpness of Hubble could measure it.

Hubble observed the nearby white dwarf star Stein 2051B as it passed in front of a background star. During the close alignment, the white dwarf’s gravity bent the light from the distant star, making it appear offset by about 2 milliarcseconds from its actual position. This deviation is so small that it is equivalent to observing an ant crawl across the surface of a quarter from 1,500 miles away.

Using the deflection measurement, the Hubble astronomers calculated that the white dwarf’s mass is roughly 68 percent of the sun’s mass. This result matches theoretical predictions.

Animation above: Looks can be deceiving. In this Hubble Space Telescope image, the white dwarf star Stein 2051B and the smaller star below it appear to be close neighbors. The stars, however, reside far away from each other. Stein 2051B is 17 light-years from Earth; the other star is about 5,000 light-years away. Stein 2051B is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein. Animation Credits: NASA, ESA, and K. Sahu (STScI).

The technique opens a window on a new method to determine a star’s mass. Normally, if a star has a companion, astronomers can determine its mass by measuring the double-star system’s orbital motion. Although Stein 2051B has a companion, a bright red dwarf, astronomers cannot accurately measure its mass because the stars are too far apart. The stars are at least 5 billion miles apart – almost twice Pluto’s present distance from the sun.

“This microlensing method is a very independent and direct way to determine the mass of a star,” explained lead researcher Kailash Sahu of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. “It’s like placing the star on a scale: the deflection is analogous to the movement of the needle on the scale.”

Sahu will present his team’s findings at 11:15 a.m. (EDT), June 7, at the American Astronomical Society meeting in Austin, Texas.

Image above: This illustration reveals how the gravity of a white dwarf star warps space and bends the light of a distant star behind it. The Hubble Space Telescope captured images of the dead star, called Stein 2051B, as it passed in front of a background star. During the close alignment, Stein 2051B deflected the starlight, which appeared offset by about 2 milliarcseconds from its actual position. Image Credits: NASA, ESA, and A. Feild (STScI).

The Hubble analysis also helped the astronomers to independently verify the theory of how a white dwarf’s radius is determined by its mass, an idea first proposed in 1935 by Indian American astronomer Subrahmanyan Chandrasekhar. “Our measurement is a nice confirmation of white-dwarf theory, and it even tells us the internal composition of a white dwarf,” said team member Howard Bond of Pennsylvania State University in University Park.

Sahu’s team identified Stein 2051B and its background star after combing through data of more than 5,000 stars in a catalog of nearby stars that appear to move quickly across the sky. Stars with a higher apparent motion across the sky have a greater chance of passing in front of a distant background star, where the deflection of light can be measured.

After identifying Stein 2051B and mapping the background star field, the researchers used Hubble’s Wide Field Camera 3 to observe the white dwarf seven different times over a two-year period as it moved past the selected background star.

The Hubble observations were challenging and time-consuming. The research team had to analyze the white dwarf’s velocity and the direction it was moving in order to predict when it would arrive at a position to bend the starlight so the astronomers could observe the phenomenon with Hubble.

The astronomers also had to measure the tiny amount of deflected starlight. “Stein 2051B appears 400 times brighter than the distant background star,” said team member Jay Anderson of STScI, who led the analysis to precisely measure the positions of stars in the Hubble images. “So measuring the extremely small deflection is like trying to see a firefly move next to a light bulb. The movement of the insect is very small, and the glow of the light bulb makes it difficult to see the insect moving.” In fact, the slight movement is about 1,000 times smaller than the measurement made by Eddington in his 1919 experiment.

Hubble Space Telescope. Animation Credits: NASA/ESA

Stein 2051B is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein. It resides 17 light-years from Earth and is estimated to be about 2.7 billion years old. The background star is about 5,000 light-years away.

The researchers plan to use Hubble to conduct a similar microlensing study with Proxima Centauri, our solar system’s closest stellar neighbor.

The team’s result will appear in the journal Science on June 9.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information about the Hubble Space Telescope, visit:

Images (mentioned), Animations (mentioned), Text, Credits: NASA/Karl Hille/Space Telescope Science Institute/Donna Weaver/Ray Villard/Kailash Sahu.

Best regards,

The Art of Exoplanets

NASA logo.

June 8, 2017

Art of Astrophysics

Video above: How do you visualize distant worlds that you can't see? A team of artists uses scientific data to imagine exoplanets and other astrophysical phenomena. Video Credits: NASA/JPL-Caltech.

The moon hanging in the night sky sent Robert Hurt’s mind into deep space -- to a region some 40 light years away, in fact, where seven Earth-sized planets crowded close to a dim, red sun.

Hurt, a visualization scientist at Caltech’s IPAC center, was walking outside his home in Mar Vista, California, shortly after he learned of the discovery of these rocky worlds around a star called TRAPPIST-1 and got the assignment to visualize them. The planets had been revealed by NASA’s Spitzer Space Telescope and ground-based observatories.

“I just stopped dead in my tracks, and I just stared at it,” Hurt said in an interview. “I was imagining that could be, not our moon, but the next planet over – what it would be like to be in a system where you could look up and see continental features on the next planet.”

Image above: This artist's concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Image Credits: NASA/JPL-Caltech.

So began a kind of inspirational avalanche. Hurt and his colleague, multimedia producer Tim Pyle, developed a series of arresting, photorealistic images of what the new system’s tightly packed planets might look like -- so tightly packed that they would loom large in each other’s skies. Their visions of the TRAPPIST-1 system would appear in leading news outlets around the world.

Artists like Hurt and Pyle, who render vibrant visualizations based on data from Spitzer and other missions, are hybrids of sorts, blending expertise in both science and art. From squiggles on charts and columns of numbers, they conjure red, blue and green worlds, with half-frozen oceans or bubbling lava. Or they transport us to the surface of a world with a red-orange sun fixed in place, and a sky full of planetary companions.

Image above: This artist's concept by Tim Pyle allows us to imagine what it would be like to stand on the surface of the exoplanet TRAPPIST-1f, located in the TRAPPIST-1 system in the constellation Aquarius. Image Credits: NASA/JPL-Caltech.

“For the public, the value of this is not just giving them a picture of something somebody made up,” said Douglas Hudgins, a program scientist for the Exoplanet Exploration Program at NASA Headquarters in Washington. “These are real, educated guesses of how something might look to human beings. An image is worth a thousand words.”

Hurt says he and Pyle are building on the work of artistic pioneers.

“There’s actually a long history and tradition for space art and science-based illustration,” he said. “If you trace its roots back to the artist Chesley Bonestell (famous in the 1950s and ’60s), he really was the artist who got this idea: Let’s go and imagine what the planets in our solar system might actually look like if you were, say, on Jupiter’s moon, Io. How big would Jupiter appear in the sky, and what angle would we be viewing it from?”

To begin work on their visualizations, Hurt divided up the seven TRAPPIST-1 planets with Pyle, who shares an office with him at Caltech’s IPAC center in Pasadena, California.

Image above: This illustration shows one possible scenario for the hot, rocky exoplanet called 55 Cancri e, which is nearly two times as wide as Earth. Robert Hurt created this in 2016. Image Credits: NASA/JPL-Caltech.

Hurt holds a Ph.D. in astrophysics, and has worked at the center since he was a post-doctoral researcher in 1996 – when astronomical art was just his hobby.

“They created a job for me,” he said.

Pyle, whose background is in Hollywood special effects, joined Hurt in 2004.

Hurt turns to Pyle for artistic inspiration, while Pyle relies on Hurt to check his science.

“Robert and I have our desks right next to each other, so we’re constantly giving each other feedback,” Pyle said. “We’re each upping each other’s game, I think.”

The TRAPPIST-1 worlds offered both of them a unique challenge. The two already had a reputation for illustrating many exoplanets – planets around stars beyond our own -- but never seven Earth-sized worlds in a single system. The planets cluster so close to their star that a “year” on each of them -- the time they take to complete a single orbit -- can be numbered in Earth days.

Image above: NASA's Kepler mission discovered a world where two suns set over the horizon instead of just one, called Kepler-16b. Robert Hurt did this illustration of this fascinating world. Image Credits: NASA/JPL-Caltech.

And like the overwhelming majority of the thousands of exoplanets found so far, they were detected using indirect means. No telescope exists today that is powerful enough to photograph them.

Real science informed their artistic vision. Using data from the telescopes that reveal each planet’s diameter as well as its “weight,” or mass, and known stellar physics to determine the amount of light each planet would receive, the artists went to work.

Both consulted closely with the planets' discovery team as they planned for a NASA announcement to coincide with a report in the journal Nature.

Image above: This artist's concept by Tim Pyle shows what the weather might look like on cool star-like bodies known as brown dwarfs. Image Credits: NASA/JPL-Caltech/University of Western Ontario/Stony Brook University.

“When we’re doing these artist’s concepts, we’re never saying, ‘This is what these planets actually look like,’” Pyle said. “We’re doing plausible illustrations of what they could look like, based on what we know so far. Having this wide range of seven planets actually let us illustrate almost the whole breadth of what would be plausible. This was going to be this incredible interstellar laboratory for what could happen on an Earth-sized planet.”

For TRAPPIST-1b, Pyle took Jupiter’s volcanic moon, Io, as an inspiration, based on suggestions from the science team. For the outermost world, TRAPPIST-1h, he chose two other Jovian moons, the ice-encased Ganymede and Europa.

After talking to the scientists, Hurt portrayed TRAPPIST-1c as dry and rocky. But because all seven planets are probably tidally locked, forever presenting one face to their star and the other to the cosmos, he placed an ice cap on the dark side.

Animation above: This artist's concept shows planet KELT-9b orbiting its host star, KELT-9. It is the hottest gas giant planet discovered so far. Animation Credits: NASA/JPL-Caltech.

TRAPPIST-1d was one of three that fall inside the “habitable zone” of the star, or the right distance away from it to allow possible liquid water on the surface.

“The researchers told us they would like to see it portrayed as something they called an ‘eyeball world,’” Hurt said. “You have a dry, hot side that’s facing the star and an ice cap on the back side. But somewhere in between, you have (a zone) where the ice could melt and be sustained as liquid water.” 

At this point, Hurt said, art intervened. The scientists rejected his first version of the planet, which showed liquid water intruding far into the “dayside” of TRAPPIST-1d. They argued that the water would most likely be found well within the planet’s dark half.

“Then I kind of pushed back, and said, ‘If it’s on the dark side, no one can look at it and understand we’re saying there’s water there,’” Hurt said. They struck a compromise: more water toward the dayside than the science team might expect, but a better visual representation of the science.

Image above: This artist's concept by Tim Pyle depicts Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone -- a range of distance from a star where liquid water might pool on the planet's surface. Image Credits: NASA/Ames/SETI Institute/JPL-Caltech.

The same push and pull between science and art extends to other forms of astronomical visualization, whether it’s a Valentine's Day cartoon of a star pulsing like a heart in time with its planet, or materials for the blockbuster announcement of the first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory in February 2016. They've also illustrated asteroids, neutron stars, pulsars and brown dwarfs.

Visualizations based on data can also inform science, leading to genuine scientific insights. The scientists’ conclusions about TRAPPIST-1 at first seemed to suggest the planets would be bathed in red light, potentially obscuring features like blue-hued bodies of water.

“It makes it hard to really differentiate what is going on,” Hurt said.

Hurt decided to investigate. A colleague provided him with a spectrum of a red dwarf star similar to TRAPPIST-1. He overlaid that with the “responsivity curves” of the human eye, and found that most of the scientists’ “red” came from infrared light, invisible to human eyes. Subtract that, and what is left is a more reddish-orange hue that we might see standing on the surface of a TRAPPIST-1 world -- “kind of the same color you would expect to get from a low-wattage light bulb,” Hurt said. “And the scientists looked at that and said, ‘Oh, ok, great, it’s orange.’ When the math tells you the answer, there really isn’t a lot to argue about.”

For Hurt, the real goal of scientific illustration is to excite the public, engage them in the science, and provide a snapshot of scientific knowledge.

“If you look at the whole history of space art, reaching back many, many decades, you will find you have a visual record,” he said. “The art is a historical record of our changing understanding of the universe. It becomes a part of the story, and a part of the research, I think.”

Related article:

Flares May Threaten Planet Habitability Near Red Dwarfs

Related link:

Caltech’s IPAC center:

For more information on exoplanets, visit:

Images (mentioned), Animation (mentioned), Video (mentioned), Text, Credits: NASA/Felicia Chou/Tony Greicius/JPL/Elizabeth Landau/Written by Pat Brennan.

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Watching a Volatile Stellar Relationship

NASA - Chandra X-ray Observatory patch.

June 8, 2017

R Aquarii (R Aqr, for short). Image credits: X-ray: NASA/CXC/SAO/R. Montez et al.; Optical: Adam Block/Mt. Lemmon SkyCenter/U. Arizona

In biology, “symbiosis” refers to two organisms that live close to and interact with one another. Astronomers have long studied a class of stars – called symbiotic stars – that co-exist in a similar way. Using data from NASA’s Chandra X-ray Observatory and other telescopes, astronomers are gaining a better understanding of how volatile this close stellar relationship can be.

R Aquarii (R Aqr, for short) is one of the best known of the symbiotic stars. Located at a distance of about 710 light years from Earth, its changes in brightness were first noticed with the naked eye almost a thousand years ago. Since then, astronomers have studied this object and determined that R Aqr is not one star, but two: a small, dense white dwarf and a cool red, giant star.

The red giant star has its own interesting properties. In billions of years, our Sun will turn into a red giant once it exhausts the hydrogen nuclear fuel in its core and begins to expand and cool. Most red giants are placid and calm, but some pulsate with periods between 80 and 1,000 days like the star Mira and undergo large changes in brightness. This subset of red giants is called “Mira variables.”

The red giant in R Aqr is a Mira variable and undergoes steady changes in brightness by a factor of 250 as it pulsates, unlike its white dwarf companion that does not pulsate. There are other striking differences between the two stars. The white dwarf is about ten thousand times brighter than the red giant. The white dwarf has a surface temperature of some 20,000 K while the Mira variable has a temperature of about 3,000 K. In addition, the white dwarf is slightly less massive than its companion but because it is much more compact, its gravitational field is stronger. The gravitational force of the white dwarf pulls away the sloughing outer layers of the Mira variable toward the white dwarf and onto its surface.

Occasionally, enough material will accumulate on the surface of the white dwarf to trigger thermonuclear fusion of hydrogen.  The release of energy from this process can produce a nova, an asymmetric explosion that blows off the outer layers of the star at velocities of ten million miles per hour or more, pumping energy and material into space. An outer ring of material provides clues to this history of eruptions.  Scientists think a nova explosion in the year 1073 produced this ring. Evidence for this explosion comes from optical telescope data, from Korean records of a “guest” star at the position of R Aqr in 1073 and information from Antarctic ice cores. An inner ring was generated by an eruption in the early 1770s. Optical data (red) in a new composite image of R Aqr shows the inner ring. The outer ring is about twice as wide as the inner ring, but is too faint to be visible in this image.

Since shortly after Chandra launched in 1999, astronomers began using the X-ray telescope to monitor the behavior of R Aqr, giving them a better understanding of the behavior of R Aqr in more recent years. Chandra data (blue) in this composite reveal a jet of X-ray emission that extends to the upper left. The X-rays have likely been generated by shock waves, similar to sonic booms around supersonic planes, caused by the jet striking surrounding material.

As astronomers have made observations of R Aqr with Chandra over the years, in 2000, 2003, and 2005, they have seen changes in this jet. Specifically, blobs of X-ray emission are moving away from the stellar pair at speeds of about 1.4 million and 1.9 million miles per hour. Despite travelling at a slower speed than the material ejected by the nova, the jets encounter little material and do not slow down much. On the other hand, matter from the nova sweeps up a lot more material and slows down significantly, explaining why the rings are not much larger than the jets.

Using the distances of the blobs from the binary, and assuming that the speeds have remained constant, a team of scientists from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass, estimated that eruptions in the 1950s and 1980s produced the blobs. These eruptions were less energetic and not as bright as the nova explosion in 1073.

Chandra X-ray Observatory. Image Credits: NASA/CXC

In 2007 a team led by Joy Nichols from CfA reported the possible detection of a new jet in R Aqr using the Chandra data. This implies that another eruption occurred in the early 2000s. If these less powerful and poorly understood events repeat about every few decades, the next one is due within the next 10 years.

Some binary star systems containing white dwarfs have been observed to produce nova explosions at regular intervals. If R Aqr is one of these recurrent novas, and the spacing between the 1073 and 1773 events repeats itself, the next nova explosion should not occur again until the 2470s. During such an event the system may become several hundred times brighter, making it easily visible to the naked eye, and placing it among the several dozen brightest stars.

Close monitoring of this stellar couple will be important for trying to understand the nature of their volatile relationship.

Rodolfo (“Rudy”) Montez of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass, presented these results at the 230th meeting of the American Astronomical Society in Austin, TX.  His co-authors are Margarita Karovska, Joy Nichols, and Vinay Kashyap, all from CfA.

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Read More from NASA's Chandra X-ray Observatory:

For more Chandra images, multimedia and related materials, visit:

Images (mentioned), Text, Credits: NASA/Lee Mohon.


The xenon connection

ESA - Rosetta Mission patch.

08 June 2017

The challenging detection, by ESA's Rosetta mission, of several isotopes of the noble gas xenon at Comet 67P/Churyumov-Gerasimenko has established the first quantitative link between comets and the atmosphere of Earth. The blend of xenon found at the comet closely resembles U-xenon, the primordial mixture that scientists believe was brought to Earth during the early stages of Solar System formation. These measurements suggest that comets contributed about one fifth the amount of xenon in Earth's ancient atmosphere.

Image above: Comet 67P/Churyumov-Gerasimenko on 15 May 2016. Image Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

Xenon – a colourless, odourless gas which makes up less than one billionth of the volume of Earth's atmosphere – might hold the key to answer a long-standing question about comets: did they contribute to the delivery of material to our planet when the Solar System was taking shape, some 4.6 billion years ago? And if so, by how much?

The noble gas xenon is formed in a variety of stellar processes, from the late phases of low- and intermediate-mass stars to supernova explosions and even neutron star mergers. Each of these phenomena gives rise to different isotopes of the element [1]. As a noble gas, xenon does not interact with other chemical species, and is therefore an important tracer of the material from which the Sun and planets originated, which in turns derives from earlier generations of stars.

"Xenon is the heaviest stable noble gas and perhaps the most important because of its many isotopes that originate in different stellar processes: each one provides an additional piece of information about our cosmic origins," says Bernard Marty from CRPG-CNRS and Université de Lorraine, France. Bernard is the lead author of a paper reporting Rosetta's discovery of xenon at Comet 67P/C-G, which is published today in Science [2].

It is because of this special 'fingerprint' that scientists have been using xenon to investigate the composition of the early Solar System, which provides important clues to constrain its formation. Over the past decades, they sampled the relative abundances of its various isotopes at different locations: in the atmosphere of Earth and Mars, in meteorites deriving from asteroids, at Jupiter, and in the solar wind – the flow of charged particles streaming from the Sun.

Graphic above: Xenon across the Solar System. Graphic Credits: Data from B. Marty et al., 2017 and references therein.

The blend of xenon present in the atmosphere of our planet contains a higher abundance of heavier isotopes with respect to the lighter ones; however, this is a result of lighter elements escaping more easily from Earth's gravitational pull and being lost to space in greater amounts. By correcting the atmospheric composition of xenon for this runaway effect, scientists in the 1970s calculated the composition of the primordial mixture of this noble gas, known as U-xenon, that was once present on Earth.

This U-xenon contained a similar mix of light isotopes to that of asteroids and the solar wind, but included significantly smaller amounts of the heavier isotopes.

"For these reasons, we have long suspected that xenon in the early atmosphere of Earth could have a different origin from the average blend of this noble gas found in the Solar System," says Bernard.

One of the explanations is that Solar System xenon derives directly from the protosolar cloud, a mass of gas and dust that gave rise to the Sun and planets, while the xenon found in the Earth's atmosphere was delivered at a later stage by comets, which in turn might have formed from a different mix of material.

With ESA's Rosetta mission visiting Comet 67P/Churyumov-Gerasimenko, an icy fossil of the early Solar System, scientists could finally gather the long-sought data to test this hypothesis.

"Searching for xenon at the comet was one of the most crucial and challenging measurements we performed with Rosetta," says Kathrin Altwegg from the University of Bern, Switzerland, principal investigator of ROSINA, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, which was used for this study.

Image above: Artist's impression of the protosolar cloud. Image Credits: ESA – CC BY-SA 3.0 IGO.

Xenon is very diffuse in the comet's thin atmosphere, so the navigation team had to fly Rosetta very close – 5 km to 8 km from the surface of the nucleus – for a period of three weeks so that ROSINA could obtain a significant detection of all the relevant isotopes.

Flying so close to the comet was extremely challenging because of the large amount of dust that was lifting off the surface at the time, which could confuse the star trackers that were used to orient the spacecraft.

Eventually, the Rosetta team decided to perform this operation in the second half of May 2016. This period was chosen as a compromise so that enough time would have passed after the comet's perihelion, in August 2015, for the dust activity to be less intense, but not too much for the atmosphere to be excessively thin and the presence of xenon hard to detect.

As a result of the observations, ROSINA identified seven isotopes of xenon, as well as several isotopes of another noble gas, krypton; these brought to three the inventory of noble gases found at Rosetta's comet, following the discovery of argon from measurements performed in late 2014.

"These measurements required a long stretch of dedicated time solely for ROSINA, and it would have been very disappointing if we hadn't detected xenon at Comet 67P/C-G, so I'm really glad that we succeeded in detecting so many isotopes," adds Kathrin.

Further analysis of the data revealed that the blend of xenon at Comet 67P/C-G, which contains larger amounts of light isotopes than heavy ones, is quite different from the average mixture found in the Solar System. A comparison with the on-board calibration sample confirmed that the xenon detected at the comet is also different from the current mix in the Earth's atmosphere.

By contrast, the composition of xenon detected at the comet seems to be closer to the composition that scientists think was present in the early atmosphere of Earth.

"This is a very exciting result because it is the first discovery of a candidate for the hypothesised U-xenon," explains Bernard.

"There are some discrepancies between the two compositions, which indicate that the primordial xenon delivered to our planet could derive from a combination of impacting comets and asteroids."

In particular, Bernard and his colleagues were able to establish the first quantitative link between comets and our planet's gaseous shroud: based on the Rosetta measurements at Comet 67P/C-G, 22 percent of the xenon once present in Earth's atmosphere could originate from comets – the rest being delivered by asteroids.

Graphic above: A link between xenon at Rosetta's comet and on Earth. Image Credits: Data from B. Marty et al., 2017 and references therein.

This result is not in contradiction with the isotopic measurements of water at Rosetta's comet, which were significantly different to that found on Earth. In fact, given the trace amounts of xenon in Earth's atmosphere and the much larger amount of water in the oceans, comets could have contributed to atmospheric xenon without having a significant impact on the composition of water in the oceans.

The contribution inferred from the xenon measurements, instead, agrees with the possibility that comets have been significant carriers of pre-biotic material – such as phosphorus and the amino acid glycine, which were also detected by Rosetta at the comet – that was crucial to the emergence of life on Earth.

Finally, the difference between the blend of xenon found at the comet – which was incorporated in the nucleus at the time of its formation – and the xenon observed across the Solar System indicates that the protosolar cloud from which the Sun, planets, and small bodies were born was a rather inhomogeneous place in terms of its chemical composition.

"This conclusion is in accord with previous measurements performed by Rosetta, including the unexpected detections of molecular oxygen (O2)) and di-sulphur (S2), and the high deuterium-to-hydrogen ratio observed in the comet water," adds Kathrin.

Additional evidence for the inhomogeneous nature of the protosolar cloud came also from anther study based on ROSINA observations, published in May in Astronomy & Astrophysics, which revealed that the mixture of silicon isotopes seen at the comet is different from what is measured elsewhere in the Solar System.

Animation above: Rosetta's big day in the Sun. 13 August 2015. ESA's Rosetta approaching perihelion of Comet 67P/Churyumov–Gerasimenko. Animation Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

"As we anticipated last year, now that mission operations are over, the teams can focus on the science," says Matt Taylor, Rosetta Project Scientist at ESA.

"The detailed analysis performed in this work, based on specially designed operations, addresses one of the mission's key scientific goals: to find quantitative clues linking back to the formation and early evolution of our planet and Solar System."


[1] The lightest isotopes of xenon (124Xe and 126Xe) are produced during supernova explosions; intermediate-mass isotopes (127Xe, 128Xe, 129Xe, 130Xe, 131Xe and 132Xe) are produced during the Asymptotic Giant Branch phase of evolved low- and intermediate-mass stars; the heaviest isotopes (134Xe and 136Xe) are produced during the merger of neutron stars.

[2] The discovery of xenon by Rosetta at Comet 67P/Churyumov-Gerasimenko was announced during a Royal Society meeting in London, UK, and on the ESA Rosetta blog in June 2016, shortly after the scientists had made the detection. This is the first peer-reviewed study based on those measurements.

Related links:

For more information about Rosetta mission, visit:

Rosetta overview:

Rosetta in depth:

Images (mentioned), Graphics (mentioned), Text, Credits: ESA/Matt Taylor/CRPG-CNRS, Université de Lorraine/Bernard Marty/Universität Bern/Kathrin Altwegg.


Galileo grows: two more satellites join working constellation

ESA - GALILEO Programme logo.

8 June 2017

Two further satellites have formally become part of Europe’s Galileo satnav system, broadcasting timing and navigation signals worldwide while also picking up distress calls across the planet.

Galileo satellite in orbit

These are the 15th and 16th satellites to join the network, two of the four Galileos that were launched together by Ariane 5 on 17 November, and the first additions to the working constellation since the start of Galileo Initial Services on 15 December.

The growing number of Galileo users around the world will draw immediate benefit from the enhanced service availability and accuracy brought by these extra satellites.

The launch into space and the manoeuvres to reach their final orbits still left a lot of rigorous testing before the satellites could join the operational constellation.

Liftoff of Galileo quartet

Their navigation and search and rescue payloads had to be switched on, checked and the performance of the different Galileo signals assessed methodically in relation to the rest of the worldwide system.

This lengthy testing saw the satellites being run from the second Galileo Control Centre in Oberpfaffenhofen, Germany, while their signals were assessed from ESA’s Redu centre in Belgium, with its specialised antennas.

The tests measured the accuracy and stability of the satellites’ atomic clocks – essential for the timing precision to within a billionth of a second as the basis of satellite navigation – as well as assessing the quality of the navigation signals.

Surveying with satnav

Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time.

Making the tests even more complicated, the satellites were visible for only three to nine hours a day from each site.

Galileo's Redu antenna

The satellites are now broadcasting working navigation signals and are ready to relay any Cospas–Sarsat distress calls to regional emergency services.

Now that these two satellites are part of the constellation, the remaining pair from the Ariane 5 launch is similarly being checked to prepare them for service. 

Related links:

Cospas–Sarsat distress calls:

Launching Galileo website:

Galileo Tour:

EC Galileo website:

European GNSS Agency:

Galileo begins serving the globe:

Galileo Initial Services: first quarter service performance for users:

Images, Text, Credits: ESA/P. Carril/S. Corvaja/CC BY-SA 3.0 IGO.


ALMA Finds Ingredient of Life Around Infant Sun-like Stars

ALMA - Atacama Large Millimeter/submillimeter Array logo.

8 June 2017

ALMA detects methyl isocyanate around young Sun-like stars

ALMA has observed stars like the Sun at a very early stage in their formation and found traces of methyl isocyanate — a chemical building block of life. This is the first ever detection of this prebiotic molecule towards solar-type protostars, the sort from which our Solar System evolved. The discovery could help astronomers understand how life arose on Earth.

Two teams of astronomers have harnessed the power of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to detect the prebiotic complex organic molecule methyl isocyanate [1] in the multiple star system IRAS 16293-2422. One team was co-led by Rafael Martín-Doménech at the Centro de Astrobiología in Madrid, Spain, and Víctor M. Rivilla, at the INAF-Osservatorio Astrofisico di Arcetri in Florence, Italy; and the other by Niels Ligterink at the Leiden Observatory in the Netherlands and Audrey Coutens at University College London, United Kingdom.

ALMA detects methyl isocyanate around young Sun-like stars (artist's impression)

“This star system seems to keep on giving! Following the discovery of sugars, we’ve now found methyl isocyanate. This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it,” explain Niels Ligterink and Audrey Coutens [2].

ALMA’s capabilities allowed both teams to observe the molecule at several different and characteristic wavelengths across the radio spectrum [3]. They found the unique chemical fingerprints located in the warm, dense inner regions of the cocoon of dust and gas surrounding young stars in their earliest stages of evolution. Each team identified and isolated the signatures of the complex organic molecule methyl isocyanate [4]. They then followed this up with computer chemical modelling and laboratory experiments to refine our understanding of the molecule’s origin [5].

IRAS 16293-2422 in the constellation of Ophiuchus

IRAS 16293-2422 is a multiple system of very young stars, around 400 light-years away in a large star-forming region called Rho Ophiuchi in the constellation of Ophiuchus (The Serpent Bearer). The new results from ALMA show that methyl isocyanate gas surrounds each of these young stars.

Earth and the other planets in our Solar System formed from the material left over after the formation of the Sun. Studying solar-type protostars can therefore open a window to the past for astronomers and allow them to observe conditions similar to those that led to the formation of our Solar System over 4.5 billion years ago.

The Rho Ophiuchi star formation region in the constellation of Ophiuchus

Rafael Martín-Doménech and Víctor M. Rivilla, lead authors of one of the papers, comment: “We are particularly excited about the result because these protostars are very similar to the Sun at the beginning of its lifetime, with the sort of conditions that are well suited for Earth-sized planets to form. By finding prebiotic molecules in this study, we may now have another piece of the puzzle in understanding how life came about on our planet.”

Niels Ligterink is delighted with the supporting laboratory results: "Besides detecting molecules we also want to understand how they are formed. Our laboratory experiments show that methyl isocyanate can indeed be produced on icy particles under very cold conditions that are similar to those in interstellar space This implies that this molecule — and thus the basis for peptide bonds — is indeed likely to be present near most new young solar-type stars."

ALMA detects ingredient of life around young Sun-like stars


[1] A complex organic molecule is defined in astrochemistry as consisting of six or more atoms, where at least one of the atoms is carbon. Methyl isocyanate contains carbon, hydrogen, nitrogen and oxygen atoms in the chemical configuration CH3NCO. This very toxic substance was the main cause of death following the tragic Bhopal industrial accident in 1984.

[2]  The system was previously studied by ALMA in 2012 and found to contain molecules of the simple sugar glycolaldehyde, another ingredient for life.

[3] The team led by Rafael Martín-Doménech used new and archive data of the protostar taken across a large range of wavelengths across ALMA’s receiver Bands 3, 4 and 6. Niels Ligterink and his colleagues used data from the ALMA Protostellar Interferometric Line Survey (PILS), which aims to chart the chemical complexity of IRAS 16293-2422 by imaging the full wavelength range covered by ALMA's Band 7 on very small scales, equivalent to the size of our Solar System.

[4] The teams carried out spectrographic analysis of the protostar’s light to determine the chemical constituents. The amount of methyl isocyanate they detected — the abundance — with respect to molecular hydrogen and other tracers is comparable to previous detections around two high-mass protostars (i.e. within the massive hot molecular cores of Orion KL and Sagittarius B2 North).

[5] Martín-Doménech’s team chemically modelled gas-grain formation of methyl isocyanate. The observed amount of the molecule could be explained by chemistry on the surface of dust grains in space, followed by chemical reactions in the gas phase. Moreover, Ligterink's team demonstrated that the molecule can be formed at extremely cold interstellar temperatures, down to 15 Kelvin (–258 degrees Celsius), using cryogenic ultra-high-vacuum experiments in their laboratory in Leiden.

More information:

This research was presented in two papers: “First Detection of Methyl Isocyanate (CH3NCO) in a solar-type Protostar” by R. Martín-Doménech et al. and “The ALMA-PILS survey: Detection of CH3NCO toward the low-mass protostar IRAS 16293-2422 and laboratory constraints on its formation”, by N. F. W. Ligterink et al.. Both papers will appear in the same issue of the Monthly Notices of the Royal Astronomical Society.

One team is composed of: R. Martín-Doménech (Centro de Astrobiología, Spain), V. M. Rivilla (INAF-Osservatorio Astrofisico di Arcetri, Italy), I. Jiménez-Serra (Queen Mary University of London, UK), D. Quénard (Queen Mary University of London, UK), L. Testi (INAF-Osservatorio Astrofisico di Arcetri, Italy; ESO, Garching, Germany; Excellence Cluster “Universe”, Germany) and J. Martín-Pintado (Centro de Astrobiología, Spain).

The other team is composed of: N. F. W. Ligterink (Sackler Laboratory for Astrophysics, Leiden Observatory, the Netherlands), A. Coutens (University College London, UK), V. Kofman (Sackler Laboratory for Astrophysics, The Netherlands), H. S. P. Müller (Universität zu Köln, Germany), R. T. Garrod (University of Virginia, USA), H. Calcutt (Niels Bohr Institute & Natural History Museum, Denmark), S. F. Wampfler (Center for Space and Habitability, Switzerland), J. K. Jørgensen (Niels Bohr Institute & Natural History Museum, Denmark), H. Linnartz (Sackler Laboratory for Astrophysics, The Netherlands) and E. F. van Dishoeck (Leiden Observatory, The Netherlands; Max-Planck-Institut für Extraterrestrische Physik, Germany).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.


Research paper: Martín-Doménech et al. 2017:

Research paper: Ligterink et al. 2017:

Photos of ALMA:

Atacama Large Millimeter/submillimeter Array (ALMA):

INAF-Osservatorio Astrofisico di Arcetri:

ESOcast 110 Light: Ingredient for life found around infant stars (4K UHD):

Images, Video, Text, Credits: Credit: ESO/Richard Hook/Digitized Sky Survey 2/L. Calçada/IAU and Sky & Telescope/Sackler Laboratory for Astrophysics/Niels Ligterink/Laboratoire d’Astrophysique de Bordeaux/Audrey Coutens/INAF-Osservatorio Astrofisico di Arcetri/Victor Rivilla/Centro de Astrobiología/Rafael Martín-Doménech.

Best regards,

Window to a watery past on Mars

ESA - Mars Express Mission patch.

8 June 2017

Perspective view across a crater in Erythraeum Chaos

This 70 km-wide crater and its surrounds offer a window into the watery past of the Red Planet.

The scene, captured by ESA’s Mars Express, is a composite of two images taken in March 2007 and February 2017.

Erythraeum Chaos in context

It focuses on a large crater in the Margaritifer Terra region in the southern hemisphere of Mars, and includes a portion of Erythraeum Chaos to the north (right in the main colour image below).

The region is located at the northern edge of Noachis Terra, which at 3.7–4 billion years old, represents some of the oldest and most heavily cratered terrain on Mars.

Margaritifer Terra and Erythraeum Chaos

Remnants of valley networks across the scene indicate that water once flowed through this region, shaping the features seen today. Indeed, as shown by the context image, Parana Valles lies to the east, while Loire Valles lies to the northwest.

There are a number of distinctive features inside the 70 km crater, such as the striking light-toned material that is interpreted as exposed bedrock.

Erythraeum Chaos and surrounds: topography

‘Chaotic terrain’ is visible both inside and outside the crater, marked by randomly oriented blocks separated by troughs.

In general, chaotic terrain is associated with the collapse of the surface above regions where large amounts of subsurface water have been released, for example by the sudden melting of ice. As such, outflow channels often begin in chaos terrains.

Erythraeum Chaos and surrounds in 3D

Chaotic terrain may also mark the sites of ancient lakes, such as in Erythraeum Chaos to the north (right) of the crater in this scene, between Loire and Parana Valles.

Related links:

Mars Express:

Mars Express overview:

Mars Express 10 year brochure:

Mars Express in-depth:

ESA Planetary Science archive (PSA):

Mars Webcam:

High Resolution Stereo Camera:

HRSC data viewer:

Behind the lens:

Frequently asked questions:

Images, Text, Credits: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO/NASA MGS MOLA Science Team.

Best regards,