vendredi 4 décembre 2015

Dual Gemini Flights Achieved Crucial Spaceflight Milestones

NASA - GEMINI Program logo.

Dec. 4, 2015

GEMINI 6 / 7 Mission patch's and spacecraft. Image Credit: NASA

The flights of two piloted spacecraft during December 1965 were major strides forward in advancing NASA's capabilities in human spaceflight. They also marked the point in which the United States clearly pulled ahead in the space race with the Soviet Union.

While Gemini VII orbited the Earth for two weeks, Gemini VI was launched, completing the first-ever rendezvous between two spacecraft in orbit. It was a transformative capability that was not only necessary for the Apollo moon landing missions, but crucial in building and operating the International Space Station. The rendezvous marked the first time a human spaceflight milestone was achieved by the United States first.

Although the Soviet Union twice had launched simultaneous pairs of Vostok spacecraft in 1962 and 1963, the cosmonauts only established radio contact, coming no closer than several miles of each other.

Image above: Gemini VII pilot Jim Lovell, in front, and command pilot Frank Borman leave the suit up trailer at Cape Kennedy's Launch Complex 16 during prelaunch countdown on Dec. 4, 1965. They are wearing lightweight pressure suits designed to be removable during their marathon 14-day mission. Image Credit: NASA.

The original plan for Gemini VI was to launch an unpiloted Agena upper stage atop an Atlas rocket on Oct. 25, 1965. As the target vehicle completed its first orbit, a Titan II launch vehicle was to lift off with astronauts Wally Schirra and Tom Stafford aboard. Gemini VI then would rendezvous and dock with the Agena.

After the Atlas rocket lifted off, the Agena's secondary engines fired to separate it from the launch vehicle. However, immediately after the Agena's primary engine fired, telemetry was lost and the target vehicle failed to reach orbit. The launch of Gemini VI was postponed.

Schirra was a member of the original seven astronauts having flown Mercury 8 for six orbits on Oct. 3, 1962. He would go on to command the first piloted Apollo mission in October 1968, becoming the only astronaut to fly in Mercury, Gemini and Apollo.

Image above: Gemini VI's Titan first stage engines shut down 1.5 seconds after ignition on Dec. 12, 1965 due to a premature release of a liftoff umbilical plug. Wally Schirra and Tom Stafford successfully launched to a rendezvous with Gemini VII three days later. Image Credit: NASA.

Stafford was one of nine pilots selected in NASA's second group of astronauts. He would serve as commander for Gemini IX in 1966, and Apollo 10, the lunar landing rehearsal mission, in 1969. He also commanded the crew of the American spacecraft that linked up with two Soviet cosmonauts as part of the Apollo-Soyuz Test Project in 1975.

Since the next Agena target vehicle would not be ready for several months, a new plan began to take shape for Schirra and Stafford.

According to "On the Shoulders of Titans: A History of Project Gemini," Walter Burke, spacecraft chief at McDonnell Aircraft Corp., and his deputy, John Yardley, asked, "Why couldn't we launch a Gemini as a target instead of an Agena?" McDonnell was the contractor that built the Gemini spacecraft.

Image above: The Gemini VII spacecraft from approximately 122 feet above as seen from Gemini VI during their rendezvous on Dec. 15, 1965. Image Credit: NASA.

NASA officials at the agency's headquarters in Washington D.C., Cape Kennedy (now Cape Canaveral) in Florida and the Manned Spacecraft Center (now Johnson Space Center) in Texas quickly began drawing up a plan to orbit Gemini VII on its planned two-week mission and, if there was no serious damage to Launch Pad 19, send up Gemini VI to rendezvous.

At first glance, some were skeptical.

"When I first heard of this plan to rendezvous two spacecraft by launching the second spacecraft from the same pad in nine days I thought it was next to impossible," said Andre Meyer Jr., senior assistant to the Gemini Program manager: "It normally takes nine weeks or 63 days of actual work to clean up the pad, erect the booster, mate the spacecraft and check out the systems."

Wiley Williams, NASA's manager of Gemini Operations at the Kennedy Space Center, explained that, while challenging, the quick turnaround was achievable.

Image above: The Gemini VII spacecraft is photographed by Tom Stafford through the hatch window of the Gemini VI spacecraft. The rendezvous and station keeping maneuvers took place at an altitude of approximately 160 miles on Dec. 15, 1965. Image Credit: NASA.

"Barring unforeseen problems, we feel there is no reason why this schedule, tight as it is, cannot be met," he said at the time. "Our most critical period will be after Gemini VII is gone. We are planning for only a few days 'turnaround' time on the pad."

According to Charles Berry, M.D., chief of Medical Programs at the Manned Spacecraft Center, Gemini VII basically was an effort to better understand how humans adapt to microgravity.

"It's the culmination of our efforts to double man's exposure to the space environment with a 14-day flight," he said. "The mission will show us that man, indeed, can adapt. That his body does not show changes that increase with his exposure to that environment. The additional data will allow us to medically commit man to a lunar mission."

The Gemini VII crew, Frank Borman and Jim Lovell, were both from the second group of astronauts. While Lovell would go on to be command pilot of Gemini XII in late 1966, both would fly together again, with Bill Anders, as part of Apollo 8, the first astronauts to orbit the moon in December 1968. As commander of Apollo 13 in 1970, Lovell became the first person to fly four times.

Image above: This view of the Gemini VI spacecraft includes a "Beat Army" sign in the window. The message from the on-board crew of Wally Schirra and Tom Stafford, who, along with Gemini VII pilot Jim Lovell, are all graduates of the U.S. Naval Academy. Gemini VII command pilot, Frank Borman, is an alumnus of the U.S. Military Academy. That year's matchup between the two service academies was played on Nov. 27, 1965, ending in a 7-7 tie. Image Credit: NASA.

"We're on our way, Frank," said Lovell as Gemini VII launched Dec. 4, 1965.

As the rocket exhaust began to clear, teams were standing by to begin preparing for Gemini VI.

"I was in the control center at Cape Kennedy watching the launch of Gemini VII and as the spacecraft was continuing into orbit, I glanced at another TV monitor and it showed the next launch vehicle being wheeled out of the hanger," said NASA Gemini Program Manager Charles Matthews. "That's how fast the action was taking place."

The longest previous spaceflight was the eight-day mission of Gemini V. Borman noted that he and Lovell hoped to take advantage of the earlier experiences.

"One of the things we got from Gemini V was that flying in the heavier spacesuits was very debilitating," he said. "So we were able to convince NASA that we should have a lightweight pressure suit which was developed in a very short period of time. It was very convenient because we could get out of it, and we did."

Borman and Lovell's work was set up to coincide with that of the prime shift team in Mission Control Houston, with both astronauts working and sleeping at the same time. The Gemini VII crew conducted 20 experiments, the most of any Gemini mission, including studies of nutrition in space.

Image above: After being picked up from the Atlantic Ocean by the crew of the USS Wasp, Tom Stafford, left, and Wally Schirra celebrate the completion of their 25-hour, 52-minute flight in which they performed the world's first rendezvous in space. Image Credit: NASA.

The next attempt to launch Schirra and Stafford turned out to be one of the most harrowing in the history of America's still young space program.

On Dec. 12, 1965, all had proceeded well right up to ignition of the twin Titan II first stage engines. Astronaut Alan Bean was serving as capsule communicator, or capcom.

"3, 2, 1, ignition … shutdown Gemini VI," he said.

After about 1.5 seconds of firing, the engines abruptly shut down. There was no liftoff.

"My clock has started," Schirra said.

Since the clock had started in the spacecraft, the instruments were telling Schirra liftoff had taken place. Mission rules dictated that he should immediately pull a D-shaped ring above the center console and activate the ejection seats, blasting the astronauts safely away from the fully fueled Titan II which would be falling back to the launch pad. However, Schirra's experience from Mercury 8 paid off. He did not feel the motion of liftoff.

"I knew we hadn't gone anywhere," he said later. "This proves that man is better programed than any computer."

An evaluation determined that a tail plug fell off prematurely causing the engine shutdown and the erroneous liftoff signal.

Three days later, Schirra and Stafford were finally on their way to catch up with Borman and Lovell.

Image above: Surrounded by NASA dignitaries and members of the crew of the aircraft carrier USS Wasp, Gemini VII astronauts Frank Borman and Jim Lovell arrive aboard the ship following their recovery on Dec. 18, 1965. The astronauts were picked up from the Atlantic Ocean, following successful splashdown after two weeks in orbit. Image Credit: NASA.

The radar on Gemini VI first made contact with Gemini VII after 3 hours and 15 minutes when they were 270 miles away. Soon thereafter, Schirra established voice contact with Borman.

"We're looking for you," the Gemini VI command pilot said. "Hang on, we'll be up there shortly."

About six hours after liftoff, while passing over the Hawaii tracking station on Gemini VI's fourth orbit, Schirra reported that he and Stafford had caught up with Borman and Lovell.

"We're flying in formation with (Gemini) VII," Schirra said. "Everything is go here."

"Roger, congratulations, excellent," said astronaut Elliott See, the capcom.

"Thank you, it was a lot of fun," said Schirra.

During the next five and a half hours of station keeping, the crews moved as close as one foot, taking pictures and describing the appearance of each spacecraft.

"Looks like the flag and the letters are seared as much at launch as they are when you come back at re-entry," Lovell said, describing the side of Gemini VI.

Later, Gemini VI fired its thrusters and slowly drifted out to 10 miles, preventing an accidental collision during their sleep period.

Before the end of the day, and noting the upcoming holiday, the Gemini VI crew had a surprise for everyone.

"Gemini VII, this is Gemini VI," Schirra said. "We have an object, looks like a satellite going from north to south, probably in a polar orbit. He's in a very low trajectory. Looks like he might be going to re-enter soon. Stand by one ..."

At that point, the sound of "Jingle Bells" was heard being played by Schirra on a small harmonica with Stafford ringing a handful of small bells.

"You're too much, VI," laughed See from mission control.

Gemini VI re-entered the next day, landing in the Atlantic Ocean within 10 miles of the aircraft carrier, USS Wasp.

The recovery of Schirra and Stafford also was the first to be televised. Through a transportable satellite Earth station on the deck of the Wasp, television networks were able to provide live coverage.

Gemini VII remained in space two days after Gemini VI's return, landing Dec. 18, 1965. Borman and Lovell held the world record for the longest human spaceflight until the 17-day Soyuz 9 mission in June 1970 and were U.S. record holders until the Skylab missions in 1973 and 1974.

"The VII and VI missions were a very fitting climax to a successful year of Gemini flights," said Matthews. "Gemini IV introduced us to spacewalking and was also the start of our buildup of long duration missions and went four days. Gemini V, in turn, went eight days. This effort on the (Gemini) 7/6 mission, is an example of the American sprit as it has existed throughout the years and is ample evidence that it exists today."

EDITOR'S NOTE: This is the fourth in a series of feature articles marking the 50th anniversary of Project Gemini. The program was designed as a steppingstone toward landing on the moon. The investment also provided technology now used in NASA's work aboard the International Space Station and planning for the Journey to Mars. In March, read about the first docking mission and responding to an emergency in space. For more see "On the Shoulders of Titans: A History of Project Gemini.":

Related article:

Gemini V: Paving the Way for Long Duration Spaceflight:

Related links:

Gemini Program:

NASA Historic Missions:

Images (mentioned), Text, Credits: NASA's Kennedy Space Center/Bob Granath.


Pluto's Layered Craters and Icy Plains & Mountainous Shoreline of Sputnik Planum

NASA - New Horizons Mission logo.

Dec. 4, 2015

Pluto's Layered Craters and Icy Plains

This highest-resolution image from NASA’s New Horizons spacecraft reveals new details of Pluto’s rugged, icy cratered plains. Notice the layering in the interior walls of many craters (the large crater at upper right is a good example). Layers in geology usually mean an important change in composition or event, but at the moment New Horizons team members do not know if they are seeing local, regional or global layering. The darker crater in the lower center is apparently younger than the others, because dark material ejected from within – its “ejecta blanket” – has not been erased and can still be made out. The origin of the many dark linear features trending roughly vertically in the bottom half of the image is under debate, but may be tectonic. Most of the craters seen here lie within the 155-mile (250-kilometer)-wide Burney Basin, whose outer rim or ring forms the line of hills or low mountains at bottom. The basin is informally named after Venetia Burney, the English schoolgirl who first proposed the name “Pluto” for the newly discovered planet in 1930. The top of the image is to Pluto’s northwest.

The Mountainous Shoreline of Sputnik Planum

In this highest-resolution image from NASA’s New Horizons spacecraft, great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Several sheer faces appear to show crustal layering, perhaps related to the layers seen in some of Pluto’s crater walls. Other materials appear crushed between the mountains, as if these great blocks of water ice, some standing as much as 1.5 miles high, were jostled back and forth. The mountains end abruptly at the shoreline of the informally named Sputnik Planum, where the soft, nitrogen-rich ices of the plain form a nearly level surface, broken only by the fine trace work of striking, cellular boundaries and the textured surface of the plain’s ices (which is possibly related to sunlight-driven ice sublimation). This view is about 50 miles wide. The top of the image is to Pluto’s northwest.

For more information about New Horizons, visit:

Images, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.

Best regards,

A new technique to gauge the distant Universe

ESA - XMM-Newton Mission patch.

Dec. 4, 2015

Scientists have developed a technique to use quasars – powerful sources driven by supermassive black holes at the centre of galaxies – to study the Universe's history and composition. To demonstrate the new method, based on a relation between a quasar's luminosity at X-ray and ultraviolet wavelengths, they made extensive use of data from ESA's XMM-Newton X-ray observatory. This approach promises to become an important tool to constrain the properties of our Universe.

At the core of most massive galaxies in the Universe is a supermassive black hole – a concentration of matter so dense that it attracts anything nearby, including light. Such black holes have masses from millions to billions of times that of the Sun and are generally idle, only accreting the occasional star or gas cloud that ventures too close to the galaxy's centre.

Image above: Artist's view of a black hole at the centre of a quasar. Image Credits: ESA/C. Carreau.

A small fraction of them are, however, extremely active, devouring matter at a very high rate, causing the surrounding material to shine brightly across the electromagnetic spectrum, from radio waves to X-rays and gamma rays. In some cases, emission from matter in the vicinity of the black hole is so intense that the core of the galaxy outshines the stars. These objects appear as point sources in the sky, like stars, and are known as quasars – short for quasi-stellar sources.

Quasars allow scientists to study gravity in the very strong field of the supermassive black holes. In addition, comparing the properties of quasars with those of other galaxies that host either active or passive black holes can reveal interesting aspects about the evolution of galaxies over cosmic history.

But one other aspect piqued the interest of two scientists from the Arcetri Astrophysical Observatory in Firenze, Italy: they realised that quasars can be used as probes of the expansion history of the Universe. The results of their study are presented in a paper, published today in the Astrophysical Journal:

"The history of cosmic expansion holds a wealth of information about the Universe, including its age and the relative abundance of its components, and to pin it down we need to observe astronomical sources at a wide range of distances from us," explains Guido Risaliti, one of the scientists who led the study.

"But determining distances in the Universe is not at all trivial and can be best performed only with a few classes of sources. In this study, we show how it can be done with quasars," he adds.

The main obstacle to measuring distances to astronomical objects lies in our ignorance of their true brightness, which makes it virtually impossible to assess whether a source is intrinsically bright or whether it just appears so because it is very close to us.

Image above: Quarars (small point sources) and galaxy clusters (larger red and yellow blobs) in an XMM-Newton image of the COSMOS field. Image Credits: ESA/XMM-Newton/G. Hasinger, N. Cappelluti, and the XMM-COSMOS collaboration.

For relatively nearby stars in our Galaxy, astronomers can get a very precise handle on distances using parallax – the tiny apparent shift of a star's position in the sky when viewed from different locations in the Earth's orbit. However, the greater the distance the smaller the parallax, which restricts the reach of this method to our local cosmic neighbourhood.

Farther away, astronomers have to rely on 'standard candles' – astronomical objects whose intrinsic luminosity can be calculated from another of their observable properties.

Amongst the most widely used standard candles are supernovae of type Ia – exploding white dwarf stars in a binary system. These explosions release roughly the same amount of energy every time, so their observed luminosity is a good indicator of the actual luminosity and, in turn, of their distance.

In the 1990s, teams of scientists collected many observations of these supernovae to map distances to faraway galaxies and to study how these are affected by the overall cosmic expansion. This led to the surprising discovery that the Universe's expansion is currently accelerating under the repulsive effect of a mysterious dark energy.

In the standard cosmological model, dark energy dominates the present Universe, making up about three quarters of its total energy budget, with the invisible dark matter accounting for about one fifth of the total, and ordinary matter amounting to a mere few percent. But it has not always been so, and delving deep into the history of our cosmos is crucial to figure out the nature and evolution of these 'dark' components.

Image above: Artist's impression of XMM-Newton spacecraft in orbit around the Earth. Image Credits: ESA/D. Ducros.

"Type Ia supernovae are a powerful tool for cosmology, but they cannot be observed at very large distances from us, so they are mostly used to probe the relatively recent Universe," says co-author Elisabeta Lusso.

Few supernovae of type Ia have been observed in earlier cosmic phases, when our almost 14 billion-year-old Universe was younger than 5 billion years.

"This is why we suggest to complement type Ia supernovae with quasars, which can be observed in large quantities out to much greater distances, probing cosmic history up to the epoch when the Universe was only one billion years of age," she adds.

To determine how far quasars are from us, Risaliti and Lusso used an interesting property of these sources: a link between the amount of light they emit at ultraviolet and X-ray wavelengths, which has been known since the late 1970s.

Both types of emission derive from the black hole's activity, although they are caused by different processes. As the accreted material flows towards the black hole through a disc, it is heated by friction and shines brightly at visible and ultraviolet wavelengths. Then, part of the light emitted by the disc interacts with nearby electrons, receiving an extra energy boost and turning into X-rays.

The key point underlying the application of this relation to cosmology is that the link between the luminosities at the two different wavelengths is not linear. This means that the ratio between a quasar's measured X-ray and ultraviolet emission is not fixed, but varies – in a known way – depending on the ultraviolet luminosity itself. So by measuring a quasar's X-ray and ultraviolet emission the scientists can estimate the absolute luminosity at ultraviolet wavelengths; in turn, this can be used to gauge the quasar's distance.

Graphic above: Determining distances of supernovae and quasars in the expanding Universe. From Risaliti & Lusso, ApJ, Vol. 815, 2015.

While the physical mechanism underlying this relation is unclear, Risaliti and Lusso could still use it to treat quasars as standard candles and employ them as distance indicators for cosmological studies.

To do so, they compiled a pilot sample of quasars with both ultraviolet and X-ray measurements, collecting 1138 sources from several data sets that were published in the scientific literature over the past decade. Most of the X-ray data came from surveys performed with ESA's XMM-Newton, including the COSMOS survey.

"First, we verified that the relation between ultraviolet and X-ray luminosity holds for quasars observed at any cosmic epoch: this is an essential condition if we want to treat them as cosmological probes," explains Risaliti.

Then, the scientists determined distances to the quasars in their sample and used these to study how the expansion of the Universe changed in the span of cosmic history covered by these sources. From this, they evaluated the relative abundance of dark matter and dark energy in the Universe, obtaining results that agree with current estimates obtained from supernovae and other observations, albeit with larger errors.

"Quasars are a less precise tool to measure distances than supernovae of type Ia, but they yield complementary information about the distant Universe that is inaccessible to supernova observations," says Lusso.

The power of this new approach is best unleashed through the combination of quasars and supernovae of type Ia, spanning over 13 billion years of cosmic evolution to investigate how the Universe changed across most of its history. In fact, combining data from current surveys of both types of sources yields constraints on the relative abundance of dark matter and dark energy that are tighter and more precise than those obtained from supernovae alone.

The method developed by Risaliti and Lusso appears especially promising in light of future surveys, since a larger quasar sample means smaller errors on the cosmological parameters.

On the X-ray front, the German-led eROSITA instrument on-board the Russian Spektr-RG satellite, planned for launch in 2017, is expected to observe millions of quasars, and ESA's Advanced Telescope for High-ENergy Astrophysics (ATHENA), planned for launch in 2028, could survey up to 10 million quasars. Meanwhile, ESA's Euclid mission, planned for launch in 2020, will observe a few million quasars at visible and near-infrared wavelengths – the portion of the spectrum where the ultraviolet light emitted by distant quasars is redshifted due to cosmic expansion.

"It is very gratifying to see that the data collected by XMM-Newton over many years are being used as the basis for a creative and promising method to investigate the darkest secrets of our Universe," comments Norbert Schartel, ESA XMM-Newton Project Scientist.

More information:

"A Hubble diagram for quasars" by Guido Risaliti and Elisabeta Lusso, is published in the Astrophysical Journal.

The study is based on a sample of 1138 quasars that was obtained by compiling many different data sets published previously in scientific papers. The sample contains an estimate of the X-ray and ultraviolet luminosity for each quasar. The X-ray data come mainly from ESA's XMM-Newton X-ray observatory, as well as from NASA's Chandra X-ray Observatory and the German Aerospace Center-led ROSAT satellite. The ultraviolet luminosity was estimated using data from the Sloan Digital Sky Survey, NASA's Galaxy Evolution Explorer (GALEX) and Spitzer Space Telescope, NOAJ's Subaru Telescope, the Canada France Hawaii Telescope (CFHT), the Two Micron All Sky Survey (2MASS) and the UKIRT Infrared Deep Sky Survey (UKIDSS).

The European Space Agency's X-ray Multi-Mirror Mission, XMM-Newton, was launched in December 1999. The largest scientific satellite to have been built in Europe, it is also one of the most sensitive X-ray observatories ever flown. More than 170 wafer-thin, cylindrical mirrors direct incoming radiation into three high-throughput X-ray telescopes. XMM-Newton's orbit takes it almost a third of the way to the Moon, allowing for long, uninterrupted views of celestial objects.

Related links:

ESA's Advanced Telescope for High-ENergy Astrophysics (ATHENA):

ESA's Euclid mission:

For more information about XMM-Newton mission, visit:

Images (mentioned), Graphic (mentioned, Text, Credits: ESA XMM-Newton Project Scientist/Norbert Schartel/INAF – Arcetri Astrophysical Observatory/Elisabeta Lusso/Guido Risaliti.

Best regards,

Hubble Peers Through the Elliptical Haze

NASA - Hubble Space Telescope patch.

Dec. 4, 2015

Like a lighthouse in the fog, the luminous core of NGC 2768 slowly fades outwards to a dull white haze in this image taken by the NASA/ESA Hubble Space Telescope.

NGC 2768 is an elliptical galaxy in the constellation of Ursa Major (The Great Bear). It is a huge bundle of stars, dominated by a bright central region, where a supermassive black hole feasts on a constant stream of gas and dust being fed to it by its galactic host.

The galaxy is also marked by a prominent plume of dust reaching out from the center and lying perpendicular to the galaxy’s plane. This dust conceals a symmetrical, S-shaped pair of jets that are being produced by the supermassive black hole as it feeds.

For images and more information about Hubble, visit: and and

Image Credits: ESA/Hubble, NASA and S. Smartt (Queen's University Belfast)/Text credit: European Space Agency/Ashley Morrow.


jeudi 3 décembre 2015

Engineers Prepare for Orion Water-Impact Testing with Precision to Protect Future Astronauts

NASA - Orion Crew Exploration Vehicle patch.

Dec. 3, 2015

When astronauts return to Earth in the Orion spacecraft, they will reenter on an extremely hot and fast journey through the atmosphere before splashing down in the Pacific Ocean. To protect the crew on landing, NASA will evaluate how the spacecraft may behave in parachute-assisted landings in different wind conditions and wave heights by conducting water-impact testing. 

NASA’s Orion spacecraft will carry humans farther into space than ever before and provide emergency abort capability, sustain the crew during the space travel, and provide safe re-entry from deep space.

Image above: Engineers at NASA’s Langley Research Center in Hampton, Virginia, coupled a NASA Orion crew module mockup with the heat shield from the spacecraft’s first flight test, Exploration Flight Test 1 (EFT-1) . The integrated Orion mockup and EFT-1 heat shield will be tested next year to simulate water landings during actual missions. Image Credits: NASA/David C. Bowman.

“The tests are designed to produce some of the most stressful water landing conditions that the spacecraft and crew may experience when returning to Earth from actual missions,” said Ellen Carpenter, project manager.

To prepare for this testing, the first major step at NASA’s Langley Research Center in Hampton, Virginia, was to couple an Orion crew module mockup with the heat shield from the spacecraft’s first flight test, Exploration Flight Test 1 (EFT-1).

"It is important to use a heat shield that is similar to what will be used on future Orion flights so the data obtained from these tests can be used to validate computer models,” Carpenter explained.

However, the heat shield, which fit perfectly with the EFT-1 Orion crew module, was not designed to mate with the mockup.

“It was challenging in the fact that we had to make sure the pieces were aligned horizontally, vertically, rotationally and then angularly,” Carpenter said.

To create perfect unity, the team had to design and fabricate integration hardware to connect the two pieces. With an accuracy of four thousandths of an inch, a laser tracker located several positions along the Orion mockup and heat shield in order to achieve nearly perfect alignment.

“This was crucial so that the integration hardware could be match drilled” Carpenter said. Match drilling is the process of precisely drilling holes through hardware components and ensures that the parts align properly in the final assembly. 

During this effort, more than 400 holes were match drilled to assemble the mockup to the heat shield. At the same time, the team prepared the remainder of the mockup for water-impact testing. These preparations included placing instruments and sensors inside the structure and installing the system that will be used to store the sensor data from the water impact tests. The team then installed the crew seats and the crew impact attenuation system that is designed to lessen the shock load on astronauts during landing.

“In basic terms, it’s like a shock absorber on your car,” clarified Chris Tarkenton, design engineer.

Image above: Engineers at NASA’s Langley Research Center in Hampton, Virginia, placed a test dummy inside a NASA Orion crew module mockup in preparation for next year’s water impact testing, which will simulate the spacecraft splashing down in the Pacific Ocean during future crewed missions. Image Credits: NASA/David C. Bowman.

Two test dummies were also installed in the crew seats. Data retrieved from sensors inside the dummies during testing will be used to evaluate the loads the crew may experience during an actual mission, which will aid in designing the systems to protect the crew from injury during water landings.

After the thorough work of joining the mockup and the heat shield for the first time, the team then disassembled the hardware to install sensors on the heat shield and conduct static tests.  A static test applies a simple force to the heat shield structure while it is not in motion to verify that the sensor readings are consistent with the computer models.

“Preliminary static testing gives us the necessary confidence to calibrate the computer analytical models that simulate landing in the ocean,” Tarkenton said. “Then we’ll take the data collected from the actual water impact testing and use it to validate the models."

Following static testing, the team can move onto final vehicle assembly and ultimately to water-impact testing. During final assembly, the team will reattach the heat shield to the mockup, waterproof the entire assembly, complete final sensor checks, and then conduct the drop tests into the Hydro Impact Basin at Langley’s Landing and Impact Research Facility.

Image above: A mockup of NASA's Orion space capsule in splashdown test. Image Credit: NASA.

Engineers have developed numerous models to anticipate possible wave and wind conditions, but full-scale testing provides insights that can't be gained from models in the laboratory. Water-impact testing will improve the accuracy of computer models that will be used to design the crew module for future Orion missions.

Nine drop tests of the integrated Orion mockup and EFT-1 heat shield will be conducted at Langley next year. These tests are but one of the many steps necessary to ensure that NASA’s new spacecraft will meet the demands of sending humans to deep space for the first time and in the future on the journey to Mars.

Related article:

Exploration Flight Test 1 (EFT-1):

LIFTOFF! Orion Begins New Era in Space Exploration!:

Related links:

Orion spacecraft:

Journey to Mars:

Images (mentioned), Text, Credits: NASA Langley Research Center/Sasha Congiu/Joe Atkinson.

Best regards,

DXL-2: Studying X-ray Emissions in Space

NASA - Wallops Flight Facility patch.

Dec. 3, 2015

The blackness of space. There isn't much visible light in space – but there are numerous other wavelengths of light and scientists want to know what's out there and where it comes from.

Diffuse x-ray emissions have long been believed to be from remnants of a supernovae which formed the local hot bubble.  However, the Diffuse X-rays from the Local Galaxy, or DXL, experiment in 2012 found that around 40 percent of this radiation is a result of the solar wind charge exchange, solar wind taking away electrons from neutral gas in space emitting x-rays.

On Dec. 4, 2015, NASA will launch the DXL-2 payload at 11:45 p.m. EST, from the White Sands Missile Range in New Mexico to continue the study of these x-rays. The launch window runs until 2:45 a.m. EST Dec. 5.

Image above: The DXL-2 payload is prepared for launch in the NASA payload assembly building at the White Sand Missile Range in New Mexico. Image Credits: NASA/Ted Gacek.

“The purpose of the flight is to better understand the nature and characteristics of the local hot bubble and solar wind charge exchange, with the double goal of understanding their fundamental physics and improving our modeling capability to use in the interpretation of past, present and future X-ray missions,” said Massimiliano Galeazzi, the DXL-2 principal investigator from the University of Miami.

The payload incorporates an upgraded University of Wisconsin Aerobee IV instrument flown on several rockets from 1973 through 1980.

The 1,497 pound DXL-2 payload will fly on a NASA Black Brant IX suborbital sounding rocket to an altitude 139 miles. The payload will be recovered and would be available for future flights.

DXL-2 is  supported through NASA’s Sounding Rocket Program at the Goddard Space Flight Center’s Wallops Flight Facility in Virginia. NASA’s Heliophysics Division manages the sounding rocket program.

For more information on the local hot bubble, solar wind charge exchange and DXL:

- Evidence for Supernovas Near Earth:

- ScienceCasts: Evidence for Supernovas Near Earth:

Related links:

Diffuse X-rays from the Local Galaxy (DXL):

Sounding Rockets:

Image (mentioned), Text, Credits: NASA's Wallops Flight Facility/Keith Koehler/Rob Garner.

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NASA Space Telescopes See Magnified Image of the Faintest Galaxy from the Early Universe

NASA - Hubble Space Telescope patch / NASA - Spitzer Space Telescope patch.

Dec. 3, 2015

Astronomers harnessing the combined power of NASA’s Hubble and Spitzer space telescopes have found the faintest object ever seen in the early universe. It existed about 400 million years after the big bang, 13.8 billion years ago.

Image above: This is a Hubble Space Telescope view of a very massive cluster of galaxies, MACS J0416.1-2403, located roughly 4 billion light-years away and weighing as much as a million billion suns. The inset is an image of an extremely faint and distant galaxy that existed only 400 million years after the big bang. Hubble captured it because the gravitational lens makes the galaxy appear 20 times brighter than normal. Image Credits: NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile).

The team has nicknamed the object Tayna, which means "first-born" in Aymara, a language spoken in the Andes and Altiplano regions of South America.

Though Hubble and Spitzer have detected other galaxies that are record-breakers for distance, this object represents a smaller, fainter class of newly-forming galaxies that until now have largely evaded detection. These very dim objects may be more representative of the early universe, and offer new insight on the formation and evolution of the first galaxies.

"Thanks to this detection, the team has been able to study for the first time the properties of extremely faint objects formed not long after the big bang," said lead author Leopoldo Infante, an astronomer at the Pontifical Catholic University of Chile. The remote object is part of a discovery of 22 young galaxies at ancient times located nearly at the observable horizon of the universe. This research is a substantial increase in the number of known very distant galaxies.

The results are published in the Dec. 3 issue of The Astrophysical Journal.

The new object is comparable in size to the Large Magellanic Cloud (LMC), a diminutive satellite galaxy of our Milky Way. It is rapidly making stars at a rate ten times faster than the LMC. The object might be the growing core of what will likely evolve into a full-sized galaxy.

The small and faint galaxy was only seen thanks to a natural "magnifying glass" in space. As part of its Frontier Fields program, Hubble observed a massive cluster of galaxies, MACS0416.1-2403, located roughly 4 billion light-years away and weighing as much as a million billion suns. This giant cluster acts as a powerful natural lens by bending and magnifying the light of far more distant objects behind it. Like a zoom lens on a camera, the cluster¹s gravity boosts the light of the distant protogalaxy to make it look 20 times brighter than normal. The phenomenon is called gravitational lensing and was proposed by Albert Einstein as part of his General Theory of Relativity.

Its distance was estimated by building a color profile from combined Hubble and Spitzer observations. The expansion of the universe causes the light from distant galaxies to be stretched or reddened with increasing distance. Though many of the galaxy's new stars are intrinsically blue-white, their light has been shifted into infrared wavelengths that are measurable by Hubble and Spitzer. Absorption by intervening cool intergalactic hydrogen also makes the galaxies look redder.

This finding suggests that the very early universe will be rich in galaxy targets for the upcoming James Webb Space Telescope to uncover. Astronomers expect that Webb will allow us to see the embryonic stages of galaxy birth shortly after the big bang.

For more information about Hubble or additional images, visit:

For more information about NASA's Spitzer Space Telescope, visit:

Image, Text, Credits: NASA/Ashley Morrow/Space Telescope Science Institute/Ray Villard.


LRO Finds Apollo 16 Booster Rocket Impact Site

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

Dec. 3, 2015

Apollo 16 S-IVB impact on the Moon

After decades of uncertainty, the Apollo 16 S-IVB impact site on the lunar surface has been identified. S-IVBs were portions of the Saturn V rockets that brought astronauts to the moon. The site was identified in imagery from the high-resolution LROC Narrow Angle Camera aboard NASA's Lunar Reconnaissance Orbiter.

Beginning with Apollo 13, the S-IVB rocket stages were deliberately impacted on the lunar surface after they were used. Seismometers placed on the moon by earlier Apollo astronauts measured the energy of these impacts to shed light on the internal lunar structure. Locations of the craters that the boosters left behind were estimated from tracking data collected just prior to the impacts.

Earlier in the LRO mission, the Apollo 13, 14, 15 and 17 impact sites were successfully identified, but Apollo 16's remained elusive. In the case of Apollo 16, radio contact with the booster was lost before the impact, so the location was only poorly known. Positive identification of the Apollo 16 S-IVB site took more time than the other four impact craters because the location ended up differing by about 30 km (about 19 miles) from the Apollo-era tracking estimate. (For comparison, the other four S-IVB craters were all within 7 km -- about four miles -- of their estimated locations).

NASA's Lunar Reconnaissance Orbiter (LRO)

Apollo 16's S-IVB stage is on Mare Insularum, about 160 miles southwest of Copernicus Crater (more precisely: 1.921 degrees north, 335.377 degrees east, minus 1,104 meters elevation).

Related Links:

- More images and information on the Apollo 16 S-IVB site from Arizona State University's LRO Camera site:

- Apollo sites revisited: recent satellite images of Apollo lunar sites:

- NASA's LRO website:

Images, Text, Credits: NASA/Goddard/Arizona State University/Rob Garner.


Mars Mission Team Addressing Vacuum Leak on Key Science Instrument

NASA - InSight Mission logo.

Dec. 3, 2015

Mission Status Report

A key science instrument that will be carried aboard NASA's Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft being prepared for launch in March 2016 is experiencing a leak in the vacuum container carrying its main sensors.  The sensors are part of an instrument called the Seismic Experiment for Interior Structure (SEIS), which is provided by the French Space Agency (CNES).

The seismometer is the prime science payload that will help answer questions about the interior structure and processes within the deep Martian interior. The SEIS instrument has three high-sensitivity seismometers enclosed in a sealed sphere. The seismometers need to operate in a vacuum in order to provide exquisite sensitivity to ground motions as small as the width of an atom.  After the final sealing of the sphere, a small leak was detected, that would have prevented meeting the science requirements once delivered to the surface of Mars.

The CNES/JPL team is currently working to repair the leak, prior to instrument integration and final environmental tests in France before shipping to the United States for installation into the spacecraft and launch.

Image above: This artist's concept from August 2015 depicts NASA's InSight Mars lander fully deployed for studying the deep interior of Mars. The mission will launch during the period March 4 to March 30, 2016, and land on Mars Sept. 28, 2016. Image Credits: NASA/JPL-Caltech.

The InSight lander has completed assembly and testing at Lockheed Martin Space Systems in Colorado, and is being prepared to ship to the Vandenberg AFB launch site. Installation of the seismometer is planned for early January. The Heat Flow and Physical Properties Package (HP3) from Germany and the rest of the scientific payload are already installed.

NASA and CNES managers are committed to launching in March and are currently assessing the launch window timeline. This will be the first launch on the West Coast of a Mars mission and the first project devoted to investigating the deep interior of the Red Planet.

The InSight Project is managed by NASA's Jet Propulsion Laboratory, Pasadena, California, for NASA’s Science Mission Directorate, Washington. Lockheed Martin is building and testing the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

For more information about InSight Mars Lander, visit:

Image (mentioned), Text, Credits: NASA/Dwayne Brown/JPL/Guy Webster.


A Distant Close-up: New Horizons’ Camera Captures a Wandering Kuiper Belt Object

NASA - New Horizons Mission logo.

Dec. 3, 2015

NASA’s New Horizons spacecraft recently took the closest images ever of a distant Kuiper Belt object – demonstrating its ability to observe numerous such bodies over the next several years if NASA approves an extended mission into the Kuiper Belt.

Animation above: Animation Credits: NASA/JHUAPL/SwRI.

In this short animation, consisting of four frames taken by the spacecraft’s Long Range Reconnaissance Imager (LORRI) on Nov. 2, and spaced an hour apart, one can see this 90-mile (150-kilometer)-wide ancient body, officially called 1994 JR1, moving against a background of stars. When these images were made, 1994 JR1 was 3.3 billion miles (5.3 billion miles) from the sun, but only 170 million miles (280 million kilometers) away from New Horizons. This sets a record, by a factor of at least 15, for the closest-ever picture of a small body in the Kuiper Belt, the solar system’s “third zone” beyond the inner, rocky planets and outer, icy gas giants.

 New Horizons spacecraft. Image Credit: NASA

Mission scientists plan to use images like these to study many more ancient Kuiper Belt objects from New Horizons if an extended mission is approved. New Horizons flew through the Pluto system on July 14, making the first close-up observations of Pluto and its family of five moons. The spacecraft is on course for a close flyby of another Kuiper Belt object, 2014 MU69, on Jan. 1, 2019.

For more information about New Horizons, visit:

Image (mentioned), Animation (mentioned), Text, Credits: NASA/Tricia Talbert.


LISA Pathfinder en route to gravitational wave demonstration

ESA - LISA Pathfinder Mission patch / Arianespace - Flight VV06 launch poster.

3 December 2015

Liftoff of Vega VV06 carrying LISA Pathfinder

ESA’s LISA Pathfinder lifted off earlier today on a Vega rocket from Europe’s spaceport in Kourou, French Guiana, on its way to demonstrate technology for observing gravitational waves from space.

Liftoff of Vega Flight VV06 with LISA Pathfinder

Gravitational waves are ripples in the fabric of spacetime, predicted a century ago by Albert Einstein’s General Theory of Relativity, published on 2 December 1915.

Einstein’s theory predicts that these fluctuations should be universal, generated by accelerating massive objects. However, they have not been directly detected to date because they are so tiny. For example, the ripples emitted by a pair of orbiting black holes would stretch a million kilometre-long ruler by less than the size of an atom.

Inside LISA Pathfinder, with narration

LISA Pathfinder will test the extraordinary technology needed to observe gravitational waves from space. At its core is a pair of identical 46 mm gold–platinum cubes separated by 38 cm, which will be isolated from all external and internal forces acting on them except one: gravity.

The mission will put these cubes in the purest free-fall ever produced in space and monitor their relative positions to astonishing precision, laying the foundations for gravitational wave observatories in space.

Such future missions will be key partners to the ground sites already searching for these elusive cosmic messengers. Space and ground experiments are sensitive to different sources of gravitational waves, both opening up new possibilities to study some of the most powerful phenomena in the Universe.

LISA Pathfinder in low-Earth orbit (C)

The Vega launcher lifted off at 04:04 GMT (05:04 CET). About seven minutes later, after separation of the first three stages, the first ignition of Vega’s upper stage propelled LISA Pathfinder into a low orbit, followed by another ignition about one hour and forty minutes into the flight.

The spacecraft separated from the upper stage at 05:49 GMT (06:49 CET). Controllers at ESA’s operations centre in Darmstadt, Germany then established control.

Over the next two weeks, the spacecraft itself will raise the orbit’s highest point in six critical burns.

The final burn will propel the spacecraft towards its operational location, orbiting around a stable virtual point in space called L1, some 1.5 million kilometres from Earth towards the Sun.

LISA Pathfinder is expected to reach its operational orbit about 10 weeks after launch, in mid-February. After final checks, it will begin its six-month scientific mission at the beginning of March.

LISA Pathfinder exploded view

En route to the final orbit, the two cubes will be released from the locking mechanisms that hold them during launch and cruise. Once in orbit around L1, the final mechanisms will be unlocked and the cubes will no longer be in mechanical contact with the spacecraft.

A complex system of laser beams bouncing between the two cubes will measure how close to true free-fall they are to within a billionth of a millimetre – never previously achieved in space.

“Fundamental research tries to understand our world,” says Johann-Dietrich Woerner, ESA’s Director General.

“Einstein’ s theoretical findings are still very impressive. With LISA Pathfinder we will try to take a further step towards confirmation of one of Einstein’s predictions: gravitational waves.”

The spacecraft itself will be an active part of the experiment, firing tiny thrusters about 10 times a second to adjust its position and avoid making contact with the cubes, thus shielding them from any forces that would prevent them from moving under the effect of gravity alone.

LISA Pathfinder’s journey through space – annotated

If these extraordinarily high-precision measurements and operations can be achieved by LISA Pathfinder, the door will be open to building a future space observatory, capable of detecting the minute disturbances in spacetime produced by gravitational waves, which are expected to be a few tens of a billionth of a millimetre over distances of millions of kilometres.

“Gravitational waves are the next frontier for astronomers. We have been looking at the Universe in visible light for millennia and across the whole electromagnetic spectrum in just the past century,” says Alvaro Giménez Cañete, ESA’s Director of Science and Robotic Exploration.

“But by testing the predictions made by Einstein one hundred years ago with LISA Pathfinder, we are paving the road towards a fundamentally new window on the Universe.”

LISA Pathfinder will operate as a physics laboratory in space. Over an intense period of six months, mission scientists will analyse the data received on Earth from each day’s operations to plan the experiments to be performed on the satellite during the following days.

LISA Pathfinder launch composite at IABG’s space test centre

“After many years of development and testing on the ground, we are looking forward to the ultimate test, which can only be run in space,” says Paul McNamara, ESA’s LISA Pathfinder project scientist.

“In a few weeks, we will be exploring the very nature of gravity in space, gaining the confidence to build a full-scale space observatory to study the gravitational Universe in the future.”

An industrial team led by the prime contractor, Airbus Defence & Space Ltd, built the spacecraft. Airbus Defence & Space GmbH provided the integrated LISA Technology Package payload and a consortium of European companies and research institutes provided its subsystemsNASA provided additional hardware and software that contributes to the mission by validating an alternative technological approach to keeping the spacecraft from making contact with the test masses.

“Integrating LISA Pathfinder posed many challenges, and we are extremely happy to see our trailblazing machine finally in space, ready to embark on its journey to L1, where it will pave the way for a new class of future space projects,” concludes César García Marirrodriga, ESA’s LISA Pathfinder project manager.

About the launcher:

The launch of LISA Pathfinder was the last of five flights intended to demonstrate the capability and flexibility of the Vega launcher system, as part of ESA’s Verta – Vega Research and Technology Accompaniment – programme.

During the Verta period, Vega has confirmed its versatility by delivering payloads into different orbits, demonstrating the full range of possible missions.

ESA was responsible for all Verta missions, which have refined and improved the launch system configuration and operations.

The Vega launches in 2015 (IXV, Sentinel-2A and LISA Pathfinder) have displayed the capacity of the system to reach three missions per year, providing confidence to customers and helping Arianespace to maintain its lead in this market segment.

The Vega launcher program is now fully qualified and ready for commercial exploitation by Arianespace.

Related links:

About LISA Pathfinder mission:

More about...

LISA Pathfinder factsheet:

Related articles:

What is gravity?:

Gravitational waves: ‘dents’ in spacetime:

Images, Videos, Text, Credits: ESA/ATG medialab/P. Sebirot, 2015/Arianespace/ Aerospace.

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mercredi 2 décembre 2015

These Are the Robots You’re Looking For

ESA - Space Robotics logo / ISS - International Space Station logo.

Dec. 2, 2015

Robonaut 2 in the Destiny laboratory. Image Credit: NASA

It seems that every science fiction story has a robot tightly woven into its narrative. Where there are space travelers, there are robotic sidekicks - often of the clunky metal figure variety - moving mechanically and speaking with a modified, monotone voice or series of beeps and bleeps. Robotics aboard the International Space Station (ISS), though, are helping us advance medical procedures on Earth and preparing us future deep space exploration. 

Throughout December, the ISS Research and Technology team will focus on the wide range of robotic advancements in which the orbiting laboratory has played a crucial role. From work that has been in progress for years and has already yielded extraordinary results here on Earth, to new technology that is set to launch this week, robotics has been and continues to be a critical part of the science taking place aboard the space station.

A view of the Canadarm2 on orbit. Image Credit: NASA

Can you imagine orbiting the Earth at 17,500 miles per hour, and using a rover on Earth to pick up a phone charger and plug it in to an outlet? Imagine being able to even feel when the plug has been inserted, all while you are hundreds of miles above the planet. Astronauts on the ISS are participating in European Space Agency (ESA) investigations where they are driving rovers here on Earth, and are performing tasks with sub-millimeter precision. Being able to send robots to the surface of a planet, operate them with extreme precision and receive tactile feedback from orbit will save money and lower risks for future exploration.

While distant exploration is benefiting from robotics aboard the space station, so are people back on Earth. The Image-Guided Autonomous Robot (IGAR) was created using technologies from both the space shuttle and space station, including the Canadian Space Agency (CSA) Canadarm, Canadarm2 and Dextre. IGAR works in tandem with an MRI scanner to aid in more precise targeting of tumors, and in needle-based biopsies or lesion removal.

Image above: Japan Aerospace Exploration Agency (JAXA) astronaut Kimiya Yui performs experiment protocols for the rack-mounted configuration of the European Space Agenecy’s (ESA’s) Haptics-1 investigation. Image Credit: NASA.

CSA’s Canadarm and Candarm2 also lead to the development of neuroArm, a surgical robot that can improve precision and accuracy during brain surgery. Watch this touching video that shows how neuroArm helped a young mother get a new lease on life after being diagnosed with multiple brain tumors.

Of course, no discussion of robotics on the space station would be complete without a mention of Robonaut2. The dexterous humanoid robot has called the space station home since 2011, and is designed to be able to complete simple, repetitive or even dangerous tasks.

Animation above: European Space Agency’s (ESA) Eurobot rover under live control by astronaut Alexander Gerst aboard the space station. Animation Credit: ESA.

New robotic technologies are continuously developed for the orbiting laboratory. The ISS Robotic External Ammonia Leak Locator (ISS External Leak Locator) is set to launch Dec. 3 aboard the Cygnus spacecraft. The tool will be tested on its ability to detect ammonia leaks on the space station’s exterior, a task that usually requires a risky spacewalk by astronauts.

Humans can do great things while in space, but having the assistance of a robot can not only advance future exploration, it can also lead to great things back on Earth. The robotic sidekicks may not look like the science fiction droids of fiction, but it’s clear their role is important. Join us as we explore these robotic stories this month.

Related links:

International Space Station (ISS):

ISS Research and Technology:

Image-Guided Autonomous Robot (IGAR):



ISS External Leak Locator:

Canadian Space Agency (CSA):

Images (mentioned), Animation (mentioned), Text, Credits: NASA’s Johnson Space Center/ Kristine Rainey/International Space Station Program Science Office/Rachel Hobson.


Cosmic filaments exposed near huge cluster

ESA - XMM-Newton Mission patch.

2 December 2015

ESA’s XMM-Newton X-ray observatory has revealed three massive filaments of hot gas flowing towards a cluster of galaxies, uncovering a portion of the cosmic skeleton that pervades the entire Universe.

Galaxies tend to congregate, forming groups and even larger agglomerates called clusters. These clusters are the most massive cosmic structures held together by gravity. As well as galaxies, they contain large amounts of hot gas and even larger amounts of invisible dark matter.

Galaxy Cluster Abell 2744

On a grander scale, galaxies and galaxy clusters appear to be linked in a gigantic filamentary network, with the most massive clusters sitting in the densest hubs of this ‘cosmic web’.

Computer simulations indicate that the cosmic web, which consists primarily of dark matter and some ordinary matter, behaves as the scaffolding of the cosmos, providing the framework for stars, galaxies and clusters to form and evolve.

In the past few decades, astronomers have detected the threadlike structure of the cosmic web in the large-scale distribution of galaxies, and found hints that diffuse gas is arranged in a similar way.

A new study using ESA’s XMM-Newton X-ray observatory has now uncovered a handful of filaments made of galaxies, gas and dark matter that are flowing towards one of the most massive galaxy clusters in the Universe, obtaining the first, unambiguous detection of gas in the cosmic web.

“This was an unexpected and most welcome discovery,” says Dominique Eckert of the University of Geneva, Switzerland, lead author of the paper reporting the new results in the journal Nature this week.

Galaxy clusters in the cosmic web

The object of the study is Abell 2744, which has been nicknamed the Pandora Cluster owing to its complex and jumbled structure. It is composed of at least four smaller components that are merging.

“We knew that this is an incredibly massive cluster hosting active processes at its core, and seeing its direct connection to the cosmic web confirms our picture of how structures form in the Universe,” adds Dr Eckert.

From 30 hours of observations by XMM-Newton in December 2014, the astronomers detected five large structures of hot gas that seem to be linked to the core of Abell 2744.

Comparing the X-ray data with optical observations, they identified the galaxies that belong to the various filaments, recognising that three of them are physically connected to the cluster, while the other two are the projection of more distant structures viewed along the same line of sight.

Just like the cluster, the filaments also contain plenty of dark matter. The astronomers have reconstructed its distribution by studying the ‘gravitational lensing’ effect that the mass of the cluster and filaments exerts on distant galaxies, modifying the path of their light and so increasing their brightness and twisting their shapes as seen by us.

“We initially looked at the inner core of Abell 2744 with the Hubble Space Telescope, with the aim of using the cluster as a strong magnifying lens to detect background galaxies that would be otherwise too faint to observe,” explains co-author Mathilde Jauzac from the University of Durham, UK.

Galaxy Cluster Abell 2744

“After the discovery of X-ray gas in these filaments, we decided to look at the gravitational lensing effect also in the outskirts of the cluster, where background galaxies are only weakly distorted and magnified, but still enable us to study the dark matter distribution near the cluster as well as in the nearby filaments.”

The combination of observations at different wavelengths revealed how the various components of Abell 2744 and its surroundings coexist.

From the X-ray data, the astronomers measured the density and temperature of the gas and compared it with the predictions from theory. With gas temperatures of 10–20 million degrees celsius, the filaments are much colder than the centre of the cluster, where the gas reaches 100 million degrees, but hotter than the average temperature in the cosmic web, estimated to be several million degrees.

The gas and galaxies in the filaments amount to about a tenth of the total mass – the rest being dark matter – which also agrees with expectations.

XMM-Newton spacecraft

While the measurements match well with the astronomers' theoretical scenario, caution is always in order when drawing conclusions about the Universe as a whole.

“What we observed is a very special configuration of dense filaments close to an exceptionally massive cluster. We need a much larger sample of less-dense filaments to investigate the nature of the cosmic web in greater detail,” says Dr Eckert.

For more in-depth investigations, astronomers will have to wait for ESA’s Athena X-ray telescope, planned for launch in 2028. Athena’s extraordinary sensitivity will make it possible to survey hot gas in the cosmic web across the sky, detecting faint and diffuse filaments and even identifying some of the atomic elements in the gas.

“With the discovery of filaments around Abell 2744, we are witnessing the build-up of the cosmic web in one of the busiest places in the known Universe, a crucial step in the study of the formation of galaxies and galaxy clusters,” says Norbert Schartel, ESA XMM-Newton Project Scientist.

For more information about XMM-Newton. visit:

More about...

XMM-Newton overview:

XMM-Newton image gallery:

In depth:

XMM-Newton in-depth:

Images, Text, Credits: ESA/XMM-Newton (X-rays); ESO/WFI (optical); NASA/ESA & CFHT (dark matter)/courtesy of K. Dolag, Universitäts-Sternwarte München, Ludwig-Maximilians-Universität München, Germany.