samedi 27 février 2016
SolarImpulse - First training flight is a success!
SolarImpulse - Around The World patch.
Feb. 27, 2016
The first Solar Impulse 2 maintenance flight took place on Friday 26 of February was uneventful. The plane took off from Kalaeloa airport at 4:32PM UTC with our test pilot, Markus Scherdel, in the cockpit, and landed at 6:05PM UTC.
Bertrand Piccard was following this long-awaited flight from the other side of the world and confessed that it was a true relief to see Si2 back in the sky of Hawaii after the last months of uncertainty.
During the hour and a half that it lasted, the team based at the Mission Control Center performed maintenance checks to verify that the technology installed in the aircraft ran smoothly, such as the stabilisation and cooling system, which both performed superbly. Si2 flew up to 8,000 feet over the Pacific Ocean and then returned to the Kalaeloa base.
This positive outcome would not have been possible without the extraordinary effort of the whole team:
- The amazing hosting of the plane on the Kalaeloa airport, thanks to the University of Hawaii and with the support of the Department of Transportation;
- The protection of the aircraft by the team which enabled it to stay safely on land since July;
- The maintenance performed by the engineers and the Mission Control Center’s hard last work to prepare this first training flight
André Borschberg was in Hawaii, following Si2’s first steps back in the air. The flight reminded him of last year’s ocean crossing from Nagoya to Hawaii. As time passes, one sometimes remembers the past as if it were a dream, but today was proof that the record-breaking flight and arrival in Hawaii in July were real!
A battery problem grounded in Hawaii Solar Impulse 2:
Cool New Batteries for Solar Impulse:
To get all the latest updates about the flights to come, don’t forget to subscribe here. You won’t regret it: http://www.solarimpulse.com/subscribe
For more information about SolarImpulse Around The World, visit: http://www.solarimpulse.com/
Image, Text, Credit: SolarImpulse.
Publié par Orbiter.ch à 12:09
vendredi 26 février 2016
CERN - In theory: Welcome to the Theory corridor
CERN - European Organization for Nuclear Research logo.
25 Feb 2016
Image above: One of CERN’s Theory corridors – along here are the offices of most of CERN’s theory department including those who were interviewed for this series of articles. (Image: Sophia Bennett/CERN).
There are corridors at CERN lined with wooden doors and rusted metal cabinets, where aged, peeling leaflets for long-a-go conferences paper the walls next to comic strips and photos.
Image above: Many of the doors along the corridor have comic strips, posters for events, or cheeky notes to the office-owners. Often the office has been held by one physicist for several years, and space on the door runs out posters spread beyond, onto the walls around until they almost merge into each other. (Image: Sophia Bennett/CERN).
Known at CERN as ‘the Theory corridor’, this is the home at CERN for some of the world’s most brilliant minds.
Image above: One of the first offices you come across belongs to Wolfgang Lerche,Head of Theory until December 2015. Lerche grew up in Munich and stands alone amongst the theorists we spoke to in that he enjoyed being practical and tinkering with radios and electronics as a child – a trait more commonly associated with experimentalists. (Image: Sophia Bennett/CERN).
Behind these heavy wooden doors, theoreticians are using equations, computer modelling and logic to try and understand the underlying laws of our universe. Here ideas, such as supersymmetry, are born, often decades before technology and experiments can provide the evidence to back those ideas up.
Image above: Many theoreticians have to travel regularly or move to different countries for their work. While senior members of staff get an office, the PhD students, summer students and visiting researchers all share offices. The white strips of paper stuck to this door are nameplates – instead of re-printing one each time, when someone moves into the office they swap their name into position, and take it out to stick back on the door once they leave. (Image: Sophia Bennett/CERN).
Theoreticians are an integral part of particle physics, providing experimentalists with a background to their research. Their work has always been a starting point for CERN physics – the "Group of Theoretical Studies" was created even before a location had been determined for CERN itself – showing physicists what and where they should be looking for the next discovery.
Image above: One of the most recognizable offices along the corridor belongs to John Ellis, of Kings College London. He has wanted to be a physicist since he was 12 years old when he took physics books out of the library as he wasn’t yet old enough to loan “good fiction”. (Image: Sophia Bennett/CERN).
Over the coming weeks, the "In Theory" series will introduce you to the Theory department and give you a behind-the-scenes glimpse of what life is like for some of the individuals within it.
Image above: His office at CERN is piled with books and papers and his blackboard is covered with notes from students – often teasing him about his research into the theory of supersymmetry (SUSY). (Image: Sophia Bennett/CERN).
Image above: The Theory Secretariat are the last office along the corridor and the hub of the department. They are vital in organising the life of the corridors – from arranging seminars to welcoming visiting theorists. (Image: Sophia Bennett/CERN).
Image above: “We’re after bigger questions, why things work the way they work, and that’s the essence of theoretical physics” - Gian Giudice is the new Head of the Theory department, seen here being interviewed for the In Theory series in his office. (Image: Sophia Bennett/CERN).
Over the next six weeks the In Theory series will publish a new article weekly on a different aspect of the Theory department, starting next week with what makes a theoretical physicist.
CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.
The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.
Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.
CERN's "Group of Theoretical Studies": http://home.cern/cern-people/opinion/2014/10/theory-cern-turns-62
For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/
Images (mentioned), Text, Credits: CERN/Harriet Jarlett/Sophia Bennett.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 13:23
NASA’s IBEX Observations Pin Down Interstellar Magnetic Field
NASA - IBEX Mission logo.
Feb. 26, 2016
Immediately after its 2008 launch, NASA’s Interstellar Boundary Explorer, or IBEX, spotted a curiosity in a thin slice of space: More particles streamed in through a long, skinny swath in the sky than anywhere else. The origin of the so-called IBEX ribbon was unknown – but its very existence opened doors to observing what lies outside our solar system, the way drops of rain on a window tell you more about the weather outside.
Now, a new study uses IBEX data and simulations of the interstellar boundary – which lies at the very edge of the giant magnetic bubble surrounding our solar system called the heliosphere – to better describe space in our galactic neighborhood. The paper, published Feb. 8, 2016, in The Astrophysical Journal Letters, precisely determines the strength and direction of the magnetic field outside the heliosphere. Such information gives us a peek into the magnetic forces that dominate the galaxy beyond, teaching us more about our home in space.
Image above: (Artist concept) Far beyond the orbit of Neptune, the solar wind and the interstellar medium interact to create a region known as the inner heliosheath, bounded on the inside by the termination shock, and on the outside by the heliopause. Image Credits: NASA/IBEX/Adler Planetarium.
The new paper is based on one particular theory of the origin of the IBEX ribbon, in which the particles streaming in from the ribbon are actually solar material reflected back at us after a long journey to the edges of the sun’s magnetic boundaries. A giant bubble, known as the heliosphere, exists around the sun and is filled with what’s called solar wind, the sun’s constant outflow of ionized gas, known as plasma. When these particles reach the edges of the heliosphere, their motion becomes more complicated.
“The theory says that some solar wind protons are sent flying back towards the sun as neutral atoms after a complex series of charge exchanges, creating the IBEX ribbon,” said Eric Zirnstein, a space scientist at the Southwest Research Institute in San Antonio, Texas, and lead author on the study. “Simulations and IBEX observations pinpoint this process – which takes anywhere from three to six years on average – as the most likely origin of the IBEX ribbon.”
Outside the heliosphere lies the interstellar medium, with plasma that has different speed, density, and temperature than solar wind plasma, as well as neutral gases. These materials interact at the heliosphere’s edge to create a region known as the inner heliosheath, bounded on the inside by the termination shock – which is more than twice as far from us as the orbit of Pluto – and on the outside by the heliopause, the boundary between the solar wind and the comparatively dense interstellar medium.
Some solar wind protons that flow out from the sun to this boundary region will gain an electron, making them neutral and allowing them to cross the heliopause. Once in the interstellar medium, they can lose that electron again, making them gyrate around the interstellar magnetic field. If those particles pick up another electron at the right place and time, they can be fired back into the heliosphere, travel all the way back toward Earth, and collide with IBEX’s detector. The particles carry information about all that interaction with the interstellar magnetic field, and as they hit the detector they can give us unprecedented insight into the characteristics of that region of space.
Image above: This simulation shows the origin of ribbon particles of different energies or speeds outside the heliopause (labeled HP). The IBEX ribbon particles interact with the interstellar magnetic field (labeled ISMF) and travel inwards toward Earth, collectively giving the impression of a ribbon spanning across the sky. Image Credits: SwRI/Zirnstein.
“Only Voyager 1 has ever made direct observations of the interstellar magnetic field, and those are close to the heliopause, where it’s distorted,” said Zirnstein. “But this analysis provides a nice determination of its strength and direction farther out.”
The directions of different ribbon particles shooting back toward Earth are determined by the characteristics of the interstellar magnetic field. For instance, simulations show that the most energetic particles come from a different region of space than the least energetic particles, which gives clues as to how the interstellar magnetic field interacts with the heliosphere.
For the recent study, such observations were used to seed simulations of the ribbon’s origin. Not only do these simulations correctly predict the locations of neutral ribbon particles at different energies, but the deduced interstellar magnetic field agrees with Voyager 1 measurements, the deflection of interstellar neutral gases, and observations of distant polarized starlight.
However, some early simulations of the interstellar magnetic field don’t quite line up. Those pre-IBEX estimates were based largely on two data points – the distances at which Voyagers 1 and 2 crossed the termination shock.
Artist's impression of the IBEX spacecraft. Image Credit: NASA
“Voyager 1 crossed the termination shock at 94 astronomical units, or AU, from the sun, and Voyager 2 at 84 AU,” said Zirnstein. One AU is equal to about 93 million miles, the average distance between Earth and the sun. “That difference of almost 930 million miles was mostly explained by a strong, very tilted interstellar magnetic field pushing on the heliosphere.”
But that difference may be accounted for by considering a stronger influence from the solar cycle, which can lead to changes in the strength of the solar wind and thus change the distance to the termination shock in the directions of Voyager 1 and 2. The two Voyager spacecraft made their measurements almost three years apart, giving plenty of time for the variable solar wind to change the distance of the termination shock.
“Scientists in the field are developing more sophisticated models of the time-dependent solar wind,” said Zirnstein.
The simulations generally jibe well with the Voyager data.
Image above: The IBEX ribbon is a relatively narrow strip of particles flying in towards the sun from outside the heliosphere. A new study corroborates the idea that particles from outside the heliosphere that form the IBEX ribbon actually originate at the sun – and reveals information about the distant interstellar magnetic field. Image Credit: SwRI.
“The new findings can be used to better understand how our space environment interacts with the interstellar environment beyond the heliopause,” said Eric Christian, IBEX program scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in this study. “In turn, understanding that interaction could help explain the mystery of what causes the IBEX ribbon once and for all.”
The Southwest Research Institute leads IBEX with teams of national and international partners. NASA Goddard manages the Explorers Program for the agency’s Heliophysics Division within the Science Mission Directorate in Washington.
- IBEX mission website: http://www.nasa.gov/mission_pages/ibex/index.html
- Article: The Astrophysical Journal Letters - "Local Interstellar Magnetic Field Determined From the Interstellar Boundary Explorer Ribbon": http://iopscience.iop.org/article/10.3847/2041-8205/818/1/L18/meta
Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Sarah Frazier/Rob Garner.
Publié par Orbiter.ch à 12:49
Hubble's Blue Bubble
NASA - Hubble Space Telescope patch.
Feb. 26, 2016
Sparkling at the center of this beautiful NASA/ESA Hubble Space Telescope image is a Wolf–Rayet star known as WR 31a, located about 30,000 light-years away in the constellation of Carina (The Keel).
The distinctive blue bubble appearing to encircle WR 31a is a Wolf–Rayet nebula — an interstellar cloud of dust, hydrogen, helium and other gases. Created when speedy stellar winds interact with the outer layers of hydrogen ejected by Wolf–Rayet stars, these nebulae are frequently ring-shaped or spherical. The bubble — estimated to have formed around 20,000 years ago — is expanding at a rate of around 220,000 kilometers (136,700 miles) per hour!
Unfortunately, the lifecycle of a Wolf–Rayet star is only a few hundred thousand years — the blink of an eye in cosmic terms. Despite beginning life with a mass at least 20 times that of the sun, Wolf–Rayet stars typically lose half their mass in less than 100,000 years. And WR 31a is no exception to this case. It will, therefore, eventually end its life as a spectacular supernova, and the stellar material expelled from its explosion will later nourish a new generation of stars and planets.
For images and more information about Hubble, visit:
Image, Text, Credits: European Space Agency (ESA)/Hubble & NASA, Acknowledgement: Judy Schmidt/Ashley Morrow.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 12:35
jeudi 25 février 2016
The Frozen Canyons of Pluto’s North Pole
NASA - New Horizons Mission logo.
Feb. 25, 2016
This ethereal scene captured by NASA’s New Horizons spacecraft tells yet another story of Pluto’s diversity of geological and compositional features—this time in an enhanced color image of the north polar area.
Long canyons run vertically across the polar area—part of the informally named Lowell Regio, named for Percival Lowell, who founded Lowell Observatory and initiated the search that led to Pluto’s discovery. The widest of the canyons (yellow in the image below) – is about 45 miles (75 kilometers) wide and runs close to the north pole. Roughly parallel subsidiary canyons to the east and west (in green) are approximately 6 miles (10 kilometers) wide. The degraded walls of these canyons appear to be much older than the more sharply defined canyon systems elsewhere on Pluto, perhaps because the polar canyons are older and made of weaker material. These canyons also appear to represent evidence for an ancient period of tectonics.
A shallow, winding valley (in blue) runs the entire length of the canyon floor. To the east of these canyons, another valley (pink) winds toward the bottom-right corner of the image. The nearby terrain, at bottom right, appears to have been blanketed by material that obscures small-scale topographic features, creating a ‘softened’ appearance for the landscape.
Large, irregularly-shaped pits (in red), reach 45 miles (70 kilometers) across and 2.5 miles (4 kilometers) deep, scarring the region. These pits may indicate locations where subsurface ice has melted or sublimated from below, causing the ground to collapse.
The color and composition of this region – shown in enhanced color – also are unusual. High elevations show up in a distinctive yellow, not seen elsewhere on Pluto. The yellowish terrain fades to a uniform bluish gray at lower elevations and latitudes. New Horizons' infrared measurements show methane ice is abundant across Lowell Regio, and there is relatively little nitrogen ice. “One possibility is that the yellow terrains may correspond to older methane deposits that have been more processed by solar radiation than the bluer terrain,” said Will Grundy, New Horizons composition team lead from Lowell Observatory, Flagstaff, Arizona.
This image was obtained by New Horizons’ Ralph/Multispectral Visible Imaging Camera (MVIC). The image resolution is approximately 2,230 feet (680 meters) per pixel. The lower edge of the image measures about 750 miles (1,200 kilometers) long. It was obtained at a range of approximately 21,100 miles (33,900 kilometers) from Pluto, about 45 minutes before New Horizons’ closest approach on July 14, 2015.
For more information about New Horizons mission, visit:
Images, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 14:25
Opportunity Mars Rover Goes Six-Wheeling up a Ridge
NASA - Mars Exploration Rover B (MER-B) patch.
Feb. 25, 2016
NASA's senior Mars rover, Opportunity, is working adeptly in some of the most challenging terrain of the vehicle's 12 years on Mars, on a slope of about 30 degrees.
Researchers are using Opportunity this month to examine rocks that may have been chemically altered by water billions of years ago. The mission's current targets of investigation are from ruddy-tinted swaths the researchers call "red zones," in contrast to tan bedrock around these zones.
The targets lie on "Knudsen Ridge," atop the southern flank of "Marathon Valley," which slices through the western rim of Endeavour Crater.
Image above: his scene from NASA's Mars Exploration Rover Opportunity looks upward at "Knudsen Ridge" from the valley below. Enhanced color makes "red zone" material on the ridge easier to recognize. Image Credits: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
A panorama of Knudsen Ridge is online at:
"We're hoping to take advantage of the steep topography that Mars provides us at Knudsen Ridge to get to a better example of the red zone material," said Steve Squyres of Cornell University, Ithaca, New York, principal investigator for the mission.
The red zone material crumbles easily. At locations in Marathon Valley where Opportunity already got a close look at it, the reddish bits are blended with other loose material accumulating in low locations. A purer exposure of the red zone material, such as some apparent on the ridge, would provide a better target for the Alpha Particle X-ray Spectrometer on Opportunity's arm, which reveals the chemical composition of rocks and soil.
Artist's view of Mars Exploration Rover "Opportunity". Image Credits: NASA/JPL
Opportunity began climbing Knudsen Ridge in late January with two drives totaling 31 feet (9.4 meters). The wheels slipped less than 20 percent up slopes as steep as 30 degrees, the steepest the rover has driven since its first year on Mars in 2004. The slip is calculated by comparing the distance the rotating wheels would have covered if there were no slippage to the distance actually covered in the drive, based on "visual odometry" imaging of the terrain the rover passes as it drives.
"Opportunity showed us how sure-footed she still is," said Mars Exploration Rover Project Manager John Callas at NASA's Jet Propulsion Laboratory, Pasadena, California. "The wheel slip has been much less than we expected on such steep slopes."
The rover made additional progress toward targets of red-zone material on Knudsen Ridge with a drive on Feb. 18.
Image above: This stereo view from NASA's Mars Exploration Rover Opportunity looks upward at "Knudsen Ridge" from the valley below. The scene appears three dimensional when viewed through blue-red glasses with the red lens on the left. It was obtained with the panoramic camera on Opportunity's mast. Image Credits: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Knudsen Ridge forms a dramatic cap overlooking the 14-mile-wide (22-kilometer-wide) Endeavour Crater. Its informal naming honors the memory of Danish astrophysicist and planetary scientist Jens Martin Knudsen (1930-2005), a founding member of the science team for Opportunity and the twin rover Spirit. "This ridge is so spectacular, it seemed like an appropriate place to name for Jens Martin," Squyres said.
Marathon Valley became a high-priority destination for the Opportunity mission when mineral-mapping observations by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), aboard NASA's Mars Reconnaissance Orbiter, located clay minerals (a type of phyllosilicate) in this valley. Clay minerals often form in the presence of water, which is why this is such a promising area of exploration. Opportunity found evidence of ancient water shortly after landing, but there were signs that the water would have been more highly acidic. The investigation in Marathon Valley could add understanding about the ancient environmental context for the presence of non-acidic water, a factor favorable for microbial life, if any has ever existed on Mars.
Image above: This scene from NASA's Mars Exploration Rover Opportunity looks upward at "Knudsen Ridge" from the valley below. Image Credits: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
"The locations of red zones in Marathon Valley correlate closely with the phyllosilicate signature we see from orbit," Squyres said. "That alone is not a smoking gun. We want to determine what it is about their chemistry that sets them apart and what it could have to do with water."
To test the idea that water affected the red zone material, the experiment underway aims to compare the chemistry of that material to the chemistry of the surrounding tan bedrock, which could represent an unaltered baseline. Opportunity used its diamond-toothed rock abrasion tool last month to scrape the crust off a tan bedrock target for an examination of the chemistry inside the rock.
The team is accomplishing productive science with Opportunity while avoiding use of the rover's flash memory, which was linked to several unplanned computer reboots last year. The only data being received from Opportunity is what can be transmitted each day before the solar-powered rover shuts down for energy-conserving overnight "sleep."
For more information about Opportunity, visit:
Images (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/Tony Greicius/JPL/Guy Webster.
Publié par Orbiter.ch à 14:14
Cluster's Earth #selfie
ESA - Cluster II Mission patch.
Feb. 25, 2016
Last week, flight controllers at ESA’s operations centre in Darmstadt, Germany, recommissioned and tested a 16-year-old webcam on one of Cluster’s four satellites.
The camera is a very low-resolution device, one of which was originally mounted on each of Samba and Rumba only to provide a simple, quick visual confirmation of separation from Salsa and Tango, respectively, during their paired launches in July and August 2000.
“It turns out the operation of the camera is quite simple and very fast, and we have also devised a way to use it in the future without interfering with the prime scientific payload activities,” says spacecraft operations manager Bruno Sousa.
It was the team’s idea to investigate whether the camera could be restarted, which Bruno saw primarily as an opportunity for training team engineers and as a way to connect with the general public interested in space technology.
“The camera had actually never been used in flight before due to a glitch during launch, but it turns out that it operates quite well after 16 years, and the team are now working to optimise exposure and post-processing settings for the recommissioned device,” he adds.
ESA's Cluster satellites in closest-ever 'dance in space'
The image comprises 27 frames mashed together into an animation. Earth is seen rotating about the centre of the image because Samba spins for stability. It’s a #selfie because, at top left, a small bit of the satellite’s second low-gain antenna can be seen.
More information on Cluster's VMC camera via ESA's Rocket Science blog: http://blogs.esa.int/rocketscience/2016/02/18/vmcsouthpole/
For more information about Cluter's Mission, visit: http://sci.esa.int/cluster/
Animation, Image, Text, Credits: European Space Agemcy (ESA)/J. Huart.
Publié par Orbiter.ch à 08:13
mercredi 24 février 2016
Pulsar Web Could Detect Low-Frequency Gravitational Waves
JPL - Jet Propulsion Laboratory logo.
Feb. 24, 2016
The recent detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) came from two black holes, each about 30 times the mass of our sun, merging into one. Gravitational waves span a wide range of frequencies that require different technologies to detect. A new study from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has shown that low-frequency gravitational waves could soon be detectable by existing radio telescopes.
"Detecting this signal is possible if we are able to monitor a sufficiently large number of pulsars spread across the sky," said Stephen Taylor, lead author of the paper published this week in The Astrophysical Journal Letters. He is a postdoctoral researcher at NASA's Jet Propulsion Laboratory, Pasadena, California. "The smoking gun will be seeing the same pattern of deviations in all of them." Taylor and colleagues at JPL and the California Institute of Technology in Pasadena have been studying the best way to use pulsars to detect signals from low-frequency gravitational waves. Pulsars are highly magnetized neutron stars, the rapidly rotating cores of stars left behind when a massive star explodes as a supernova.
Einstein's general theory of relativity predicts that gravitational waves -- ripples in spacetime -- emanate from accelerating massive objects. Nanohertz gravitational waves are emitted from pairs of supermassive black holes orbiting each other, each of which contain millions or a billion times more mass than those detected by LIGO. These black holes each originated at the center of separate galaxies that collided. They are slowly drawing closer together and will eventually merge to create a single super-sized black hole.
Image above: Gravitational waves are ripples in space-time, represented by the green grid, produced by accelerating bodies such as interacting supermassive black holes. These waves affect the time it takes for radio signals from pulsars to arrive at Earth. Image Credits: David Champion.
As they orbit each other, the black holes pull on the fabric of space and create a faint signal that travels outward in all directions, like a vibration in a spider's web. When this vibration passes Earth, it jostles our planet slightly, causing it to shift with respect to distant pulsars. Gravitational waves formed by binary supermassive black holes take months or years to pass Earth and require many years of observations to detect.
"Galaxy mergers are common, and we think there are many galaxies harboring binary supermassive black holes that we should be able to detect," said Joseph Lazio, one of Taylor's co-authors, also based at JPL. "Pulsars will allow us to see these massive objects as they slowly spiral closer together."
Once these gigantic black holes get very close to each other, the gravitational waves are too short to detect using pulsars. Space-based laser interferometers like eLISA, a mission being developed by the European Space Agency with NASA participation, would operate in the frequency band that can detect the signature of supermassive black holes merging. The LISA Pathfinder mission, which includes a stabilizing thruster system managed by JPL, is currently testing technologies necessary for the future eLISA mission.
Finding evidence for supermassive black hole binaries has been a challenge for astronomers. The centers of galaxies contain many stars, and even monstrous black holes are quite small -- comparable to the size of our solar system. Seeing visible signatures of these binaries amid the glare of the surrounding galaxy has been difficult for astronomers.
Radio astronomers search instead for the gravitational signals from these binaries. In 2007, NANOGrav began observing a set of the fastest-rotating pulsars to try to detect tiny shifts caused by gravitational waves.
Pulsars emit beams of radio waves, some of which sweep across Earth once every rotation. Astronomers detect this as a rapid pulse of radio emission. Most pulsars rotate several times a second. But some, called millisecond pulsars, rotate hundreds of times faster.
"Millisecond pulsars have extremely predictable arrival times, and our instruments are able to measure them to within a ten-millionth of a second," said Maura McLaughlin, a radio astronomer at West Virginia University in Morgantown and member of the NANOGrav team. "Because of that, we can use them to detect incredibly small shifts in Earth's position."
But astrophysicists at JPL and Caltech caution that detecting faint gravitational waves would likely require more than a few pulsars. "We're like a spider at the center of a web," said Michele Vallisneri, another member of the JPL/Caltech research group. "The more strands we have in our web of pulsars, the more likely we are to sense when a gravitational wave passes by."
Vallisneri said accomplishing this feat will require international collaboration. "NANOGrav is currently monitoring 54 pulsars, but we can only see some of the southern hemisphere. We will need to work closely with our colleagues in Europe and Australia in order to get the all-sky coverage this search requires."
The feasibility of this approach was recently called into question when a group of Australian pulsar researchers reported that they were unable to detect such signals when analyzing a set of pulsars with the most precise timing measurements. After studying this result, the NANOGrav team determined that the reported non-detection was not a surprise, and resulted from the combination of optimistic gravitational wave models and analysis of too few pulsars. Their one-page response was released recently via the arXiv electronic print service.
Despite the technical challenges, Taylor is confident their team is on the right track. "Gravitational waves are washing over Earth all the time," Taylor said. "Given the number of pulsars being observed by NANOGrav and other international teams, we expect to have clear and convincing evidence of low-frequency gravitational waves within the next decade."
NANOGrav is a collaboration of over 60 scientists at more than a dozen institutions in the United States and Canada. The group uses radio pulsar timing observations acquired at NRAO's Green Bank Telescope in West Virginia and at Arecibo Radio Observatory in Puerto Rico to search for ripples in the fabric of spacetime. In 2015, NANOGrav was awarded $14.5 million by the National Science Foundation to create and operate a Physics Frontiers Center.
"With the recent detection of gravitational waves by LIGO, the outstanding work of the NANOGrav collaboration is particularly relevant and timely," said Pedro Marronetti, National Science Foundation program director for gravitational wave research. "This NSF-funded Physics Frontier Center is poised to complement LIGO observations, extending the window of gravitational wave detection to very low frequencies."
One-page response: http://arxiv.org/abs/1602.06301
Jet Propulsion Laboratory (JPL): https://www.nasa.gov/centers/jpl/home/index.html
For additional information, visit: http://nanograv.org/
Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau/NANOGrav/Elizabeth Ferrara/Written by Elizabeth Ferrara of NANOGrav.
Publié par Orbiter.ch à 12:56
Simulated satellite reentries offering safety insights
ESA - Cleansat logo.
24 February 2016
It’s not often that space engineers get to practise the destruction of satellites, but a team came together at ESA to simulate and analyse just that – the culmination of a 14-month ‘design for demise’ project.
New space debris mitigation regulations demand future missions have a less than one in 10 000 chance of someone on the ground being hit by debris.
The most straightforward solution would be controlled reentries into empty stretches of ocean – except this turns out to need significantly more propellant, so would require a larger satellite and a bigger, more costly rocket.
The best alternative is to design and build satellites in such a way that they would burn up in the atmosphere. Space manufacturers, working with ESA’s Clean Space initiative – tasked with safeguarding both terrestrial and orbital environment – have been investigating this, as part of a larger programme called CleanSat.
“Clean Space asked industry to assess all the techniques and see what effects they would have on the different areas of satellite design, such as structures, propulsion, power and orbital control,” said Luisa Innocenti, heading Clean Space.
ESA’s technical centre in Noordwijk, the Netherlands, is equipped with networked software tools to enable disparate specialists to work together on a single design in real time.
D4D session at CDF
The studies identified critical items most likely to survive reentry, such as titanium propellant tanks, reaction wheels, optical payloads and balance masses.
Information on the key factors influencing the survivability of each item was also provided – these include not only the material it is made from and its mass but also its geometry, wall thickness and position within the satellite, which influence its overall heat exposure through shielding by other elements.
Many solutions were proposed, ranging from substituting materials to relocating items to places where they will receive more heating earlier in the reentry process, and even triggering a partial breakup of the structure during reentry to guarantee destruction.
Reentry simulation software
Finally, they were applied individually and in combination to actual missions, in this case the Earth-observing Sentinel-1 and Sentinel-2 satellites, serving to identify valuable guidelines and areas requiring further investigation.
“The topic is highly complex, and ESA really is the world leader,” added Friederike Beyer, assisting on the study. “This creates exciting technical discussions, although often it can be hard to come to clear conclusions.
“The results showed these techniques can provide real improvements, but further work on both destructible elements and reentry software tools will be needed to reach our goal.”
About Clean Space:
What is Clean Space?: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/What_is_Clean_Space
Concurrent Design Facility: http://www.esa.int/Our_Activities/Space_Engineering_Technology/CDF
CleanSat: new satellite technologies for cleaner low orbits: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/CleanSat_new_satellite_technologies_for_cleaner_low_orbits
ESA invites ideas to cut space debris creation: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/ESA_invites_ideas_to_cut_space_debris_creation
Developing anti-space debris technologies: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Developing_anti-space_debris_technologies
Images, Text, Credits: European Space Agency (ESA).
Publié par Orbiter.ch à 08:48
ATLASGAL Survey of Milky Way Completed
ESO - European Southern Observatory logo.
24 February 2016
The southern plane of the Milky Way from the ATLASGAL survey
A spectacular new image of the Milky Way has been released to mark the completion of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). The APEX telescope in Chile has mapped the full area of the Galactic Plane visible from the southern hemisphere for the first time at submillimetre wavelengths — between infrared light and radio waves — and in finer detail than recent space-based surveys. The pioneering 12-metre APEX telescope allows astronomers to study the cold Universe: gas and dust only a few tens of degrees above absolute zero.
APEX, the Atacama Pathfinder EXperiment telescope, is located at 5100 metres above sea level on the Chajnantor Plateau in Chile’s Atacama region. The ATLASGAL survey took advantage of the unique characteristics of the telescope to provide a detailed view of the distribution of cold dense gas along the plane of the Milky Way galaxy . The new image includes most of the regions of star formation in the southern Milky Way .
The southern plane of the Milky Way from the ATLASGAL survey
The new ATLASGAL maps cover an area of sky 140 degrees long and 3 degrees wide, more than four times larger than the first ATLASGAL release . The new maps are also of higher quality, as some areas were re-observed to obtain a more uniform data quality over the whole survey area.
The ATLASGAL survey is the single most successful APEX large programme with nearly 70 associated science papers already published, and its legacy will expand much further with all the reduced data products now available to the full astronomical community .
The southern plane of the Milky Way from the ATLASGAL survey (annotated)
At the heart of APEX are its sensitive instruments. One of these, LABOCA (the LArge BOlometer Camera) was used for the ATLASGAL survey. LABOCA measures incoming radiation by registering the tiny rise in temperature it causes on its detectors and can detect emission from the cold dark dust bands obscuring the stellar light.
The new release of ATLASGAL complements observations from ESA's Planck satellite . The combination of the Planck and APEX data allowed astronomers to detect emission spread over a larger area of sky and to estimate from it the fraction of dense gas in the inner Galaxy. The ATLASGAL data were also used to create a complete census of cold and massive clouds where new generations of stars are forming.
Comparison of the central part of the Milky Way at different wavelengths
“ATLASGAL provides exciting insights into where the next generation of high-mass stars and clusters form. By combining these with observations from Planck, we can now obtain a link to the large-scale structures of giant molecular clouds,” remarks Timea Csengeri from the Max Planck Institute for Radio Astronomy (MPIfR), Bonn, Germany, who led the work of combining the APEX and Planck data.
Comparison of the central part of the Milky Way at different wavelengths (annotated)
The APEX telescope recently celebrated ten years of successful research on the cold Universe. It plays an important role not only as pathfinder, but also as a complementary facility to ALMA, the Atacama Large Millimeter/submillimeter Array, which is also located on the Chajnantor Plateau. APEX is based on a prototype antenna constructed for the ALMA project, and it has found many targets that ALMA can study in great detail.
Comparison of the central part of the Milky Way at different wavelengths
Leonardo Testi from ESO, who is a member of the ATLASGAL team and the European Project Scientist for the ALMA project, concludes: “ATLASGAL has allowed us to have a new and transformational look at the dense interstellar medium of our own galaxy, the Milky Way. The new release of the full survey opens up the possibility to mine this marvellous dataset for new discoveries. Many teams of scientists are already using the ATLASGAL data to plan for detailed ALMA follow-up.”
Close look at the ATLASGAL image of the plane of the Milky Way
 The map was constructed from individual APEX observations of radiation with a wavelength of 870 µm (0.87 millimetres).
 The northern part of the Milky Way had already been mapped by the James Clerk Maxwell Telescope (JCMT) and other telescopes, but the southern sky is particularly important as it includes the Galactic Centre, and because it is accessible for detailed follow-up observations with ALMA.
 The first data release covered an area of approximately 95 square degrees, a very long and narrow strip along the Galactic Plane two degrees wide and over 40 degrees long. The final maps now cover 420 square degrees, more than four times larger.
 The data products are available through the ESO archive: http://archive.eso.org/wdb/wdb/adp/phase3_main/form?phase3_collection=ATLASGAL&release_tag=1
 The Planck data cover the full sky, but with poor spatial resolution. ATLASGAL covers only the Galactic plane, but with high angular resolution. Combining both provides excellent spatial dynamic range.
ATLASGAL is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Max Planck Institute for Astronomy (MPIA), ESO, and the University of Chile.
APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is carried out by ESO.
ALMA is a partnership of the 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).
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, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
The ATLASGAL survey: http://www3.mpifr-bonn.mpg.de/div/atlasgal/index.html
LABOCA (the LArge BOlometer Camera) : https://www.eso.org/public/teles-instr/apex/laboca/
Max-Planck-Institute for Radio Astronomy (MPIfR): http://www.mpifr-bonn.mpg.de/2169/en
Onsala Space Observatory (OSO): http://www.chalmers.se/en/centres/oso/Pages/default.aspx
ATLASGAL information at MPIfR: http://www3.mpifr-bonn.mpg.de/div/atlasgal/index.html
The Csengeri et al. 2016 paper on the combination with Planck data: http://esoads.eso.org/abs/2016A%26A...585A.104C
ATLASGAL papers linked in the ESO Telescope Bibliography: http://telbib.eso.org/?q=atlasgal&boolany=or&boolaut=or&boolti=or&yearto=2016&boolins=or&booltel=or&search=Search
ESA's Planck satellite: http://www.esa.int/Our_Activities/Space_Science/Planck_overview
First ATLASGAL release: https://www.eso.org/public/news/eso0924/
Images, Text, Credits: ESO/APEX/ATLASGAL consortium/NASA/GLIMPSE consortium/ESA/Planck/D. Minniti/S. GuisardAcknowledgement: Ignacio Toledo, Martin Kornmesser/Videos: ESO/APEX/ATLASGAL consortium/NASA/GLIMPSE consortium/ESA/Planck/VVV Survey/D. Minniti/S. Guisard/Acknowledgement: Ignacio Toledo, Martin Kornmesser. Music: Johan B. Monell (www.johanmonell.com).
Best regards, Orbiter.ch
Publié par Orbiter.ch à 08:35
Freefall achieved on LISA Pathfinder
ESA - LISA Pathfinder Mission patch.
24 February 2016
On Monday, the two cubes housed in the core of ESA’s LISA Pathfinder were left to move under the effect of gravity alone – another milestone towards demonstrating technologies to observe gravitational waves from space.
It has been an intense couple of months for LISA Pathfinder. After launch on 3 December and six burns to raise the orbit, it finally reached its work site – 1.5 million km from Earth towards the Sun – in January, and the team of engineers and scientists started to switch on and test its systems.
LISA Pathfinder operating in space
One of the most delicate operations entailed releasing the two test masses from the mechanisms that kept them in place during ground handling, launch and cruise.
First, the eight locking ‘fingers’ pressing on the corners of the identical gold–platinum cubes were retracted on 3 February. The cubes were then being held in position only by two rods, softly pushing on opposite faces.
These rods were retracted from the first test mass on 15 February, and from the second on the following day, leaving the cubes floating freely several millimetres from the walls of their housings.
The successful release of the two cubes, floating in space 1.5 million km away, left the team members thrilled and delighted.
LISA Pathfinder exploded view
Over the following days, minute electrostatic forces were applied to manoeuvre the cubes and make them track the spacecraft’s motion through space as it is slightly disturbed by external forces such as the pressure from sunlight.
This enabled the team to run further tests on the instruments, including the system used to measure the electrical charge of each cube and the procedures used to monitor their position and orientation.
Then the team aligned the two cubes with the laser beams that link them, and checked that the laser measurements agreed with those from the electrostatic sensors.
After verifying that everything was working as planned, the intensity of the electrostatic forces was gradually reduced until none was being applied along the sensitive axes of the masses. This resulted in a brief test of drag-free motion, on 19 February.
Finally, on 22 February, the team tackled the greatest challenge: setting the two cubes completely free, letting them move under the effect of gravity alone and actively manoeuvring the spacecraft around them.
To do this, LISA Pathfinder measures the position and orientation of each cube, and corrects its movement by firing microthrusters to keep it centred on one cube.
“This is a historic achievement: we are demonstrating the most precise freefall that has ever been obtained in space,” says Paul McNamara, LISA Pathfinder project scientist.
On 23 February, the spacecraft’s main operating mode was switched on for the first time. With the test masses in freefall, all of the key elements are now in place to start LISA Pathfinder’s scientific mission on 1 March, following some final tests on the fully operational payload in the coming days.
Inside LISA Pathfinder, with narration
Reproducing a motion as close as possible to actual freefall is the challenging condition needed to build and operate future space missions to observe gravitational waves.
Albert Einstein predicted the existence of gravitational waves, fluctuations in the fabric of spacetime, a century ago and they were recently directly detected with the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO), as announced on 11 February.
Space and ground experiments are sensitive to different sources of gravitational waves, so future space missions will be key partners to ground facilities such as LIGO, the European Gravitational Observatory and the Virgo Collaboration, which are already active in this quest.
A spaceborne gravitational wave observatory was identified as the goal for the L3 mission in ESA’s Cosmic Vision programme, and LISA Pathfinder will lay the foundations for these future investigations of the gravitational Universe.
“It is an immense reward to see this pioneering spacecraft ready to start its crucial mission,” concludes César García Marirrodriga, ESA’s project manager.
About LISA Pathfinder mission: http://sci.esa.int/lisa-pathfinder/
LISA Pathfinder factsheet: http://www.esa.int/Our_Activities/Space_Science/LISA_Pathfinder_factsheet
What is gravity?: http://www.esa.int/Our_Activities/Space_Science/What_is_gravity
Gravitational waves: ‘dents’ in spacetime: http://www.esa.int/Our_Activities/Space_Science/Gravitational_waves_dents_in_spacetime
Images, Video, Text, Credits: ESA/ATG medialab/Markus Bauer/Paul McNamara/César García Marirrodriga/Stefano Vitale.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 08:06
mardi 23 février 2016
Repair Tasks Dominate Tuesday for Expedition 46 & Cygnus departure
ISS - Expedition 46 Mission patch.
February 23, 2016
International Space Station (ISS)
The crew of Expedition 46 was engaged in a variety of repair tasks today across the orbiting laboratory. ESA astronaut Tim Peake replaced cables in the station’s Advanced Resistive Exercise Device, the primary tool for astronaut resistive exercise vital for maintaining bone and muscle mass while in microgravity. NASA astronauts Scott Kelly and Tim Kopra worked to replace key components in the station’s Water Processing Assembly.
Peake also set up units for the NASA Space Automated Bioproduct Laboratory (SABL), which is capable of supporting life science research on microorganisms, small organisms, animal cells, tissue cultures and small plants.
Image above: Image shared by Expedition 46 Commander Scott Kelly with the caption “#Countdown Let’s take this 16 sunsets at a time. 8 days to go tomorrow! #GoodNight from @space_station! #YearInSpace.”
Meanwhile, Scott Kelly and Mikhail Kornienko are just one week away from the conclusion of their one-year mission. The pair are set to land in Kazakhstan at 11:27 p.m. EST March 1.
Spaceship Takes Out Trash Before One-Year Crew Goes Home
The Expedition 46 crew took out the trash today when it released the Orbital ATK Cygnus spacecraft from the grips of the International Space Station’s Canadarm2 robotic arm. In less than two weeks, another spacecraft will leave returning three crew members back to Earth.
Successful Commercial Space Station Supply Mission Concludes
The Cygnus was filled with trash and discarded gear over the last few days before the hatches were closed Thursday. Ground controllers then remotely guided the Canadarm2 to grapple Cygnus and detach it from the Unity module.
Image above: There are now four spacecraft docked to the International Space Station after the Cygnus left Friday morning. The next spacecraft to leave will be the Soyuz TMA-18M docked to the Poisk module on March 1.
NASA astronauts Scott Kelly and Tim Kopra commanded the Canadarm2 to release Cygnus February 19 (Friday) at 7:26 a.m. EST when it began gracefully departing the vicinity of the station. Orbital ATK controllers in Virginia will guide Cygnus into the Earth’s atmosphere Saturday morning where it will safely burn up high over the Pacific Ocean.
Image above: The Cygnus spacecraft is released from the International Space Station’s Canadarm2.
Kelly and a pair of cosmonauts Mikhail Kornienko and Sergey Volkov now turn their attention to their March 1 homecoming. They will be packing the Soyuz TMA-18M with science experiments and personal items for the ride home. Kelly and Kornienko will be completing 340 consecutive days in space, while Volkov will be wrapping up 182 days in orbit.
- Advanced Resistive Exercise Device:
- Space Automated Bioproduct Laboratory (SABL):
- International Space Station (ISS): http://www.nasa.gov/mission_pages/station/main/index.html
- Space Station Research and Technology:
Images, Video, Text, Credits: NASA/NASA TV/Mark Garcia.
Publié par Orbiter.ch à 14:41
A strange music heard behind the moon by Apollo 10 in 1969
NASA - Apollo 10 Mission patch.
Feb. 23, 2016
Image above: Earth view from the Moon. It is passing behind the moon the astronauts have heard a strange music.
A recording of the Nasa of "weird music" heard by the crew of Apollo 10 in May 1969 during their flight over the far side of the Moon caused a stir after a television report.
The three astronauts Thomas P. Stafford, commander John Young, pilot of the control module and Eugene Cernan, lunar module pilot, were conducting the general repetition of flight before the first moon landing July 21, 1969 during the Apollo 11 mission, which was Neil Armstrong.
For these whistles was presented Sunday night on the cable channel Discovery as part of its series "Unexplained records of NASA." These sounds have almost lasted an hour. They were recorded and transmitted to the control center in Houston (Texas, Southern United States) where they were transcribed and archived.
Extract from Discovery documentary:
Outer Space Music Pt 2 of 2 - NASA's Unexplained Files
The soundtrack, available in the archives of NASA since 1973, has been digitized in 2012 has recently surfaced.
"You hear that? That whistle," said Eugen Cernan on the recording. "It's really a strange music," he continues while their ship flies over the far side of the Moon at 1500 meters, cut off from radio contact with Earth.
Taken for fools?
Apollo 10 Crew, left to right: Cernan, Stafford, Young
The three astronauts felt the strange phenomenon so that they debated as to whether or not they had to report to the control center to their superiors for fear of not being taken seriously and jeopardize their chances of make future flights, according to the Discovery documentary.
As bizarre as these sounds may have been, they do not have an extraterrestrial origin, NASA insists. An engineer from the space agency interviewed in the program explained that "the radios in the two vessels, the lunar module and command module (when attached), created interference between them."
For more information about Apollo 10 Mission, visit:
NASA History: http://www.nasa.gov/topics/history/index.html
Apollo 10 Mission: https://en.wikipedia.org/wiki/Apollo_10
Images, Video, Text, Credits: ATS/NASA/Wikimedia/Discovery/Youtube/Orbiter.ch Aerospace/Roland Berga.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 05:10
Inscription à : Articles (Atom)