 GREENBELT, Md - Thanks to the presence of a natural "zoom lens" in space, NASA's Hubble Space Telescope got a uniquely close-up look at the brightest "magnified" galaxy yet discovered.
This observation provides a unique opportunity to study the physical properties of a galaxy vigorously forming stars when the universe was only one-third its present age. A so-called gravitational lens is produced when space is warped by a massive foreground object, whether it is the sun, a black hole or an entire cluster of galaxies. The light from more-distant background objects is distorted, brightened and magnified as it passes through this gravitationally disturbed region.
A team of astronomers led by Jane Rigby of NASA's Goddard Space Flight Center in Greenbelt, Md., aimed Hubble at one of the most striking examples of gravitational lensing, a nearly 90-degree arc of light in the galaxy cluster RCS2 032727-132623. Hubble's view of the distant background galaxy is significantly more detailed than could ever be achieved without the help of the gravitational lens.
The results have been accepted for publication in the Astrophysical Journal, in a paper led by Keren Sharon of the Kavli Institute for Cosmological Physics at the University of Chicago. Professor Michael Gladders and graduate student Eva Wuyts of the University of Chicago were also key team members.
The presence of the lens helps show how galaxies evolved from 10 billion years ago to today. While nearby galaxies are fully mature and are at the tail end of their star-formation histories, distant galaxies tell us about the universe's formative years. The light from those early events is just now arriving at Earth. Very distant galaxies are not only faint but also appear small on the sky. Astronomers would like to see how star formation progressed deep within these galaxies. Such details would be beyond the reach of Hubble's vision were it not for the magnification made possible by gravity in the intervening lens region.
In 2006 a team of astronomers using the Very Large Telescope in Chile measured the arc's distance and calculated that the galaxy appears more than three times brighter than previously discovered lensed galaxies. In 2011 astronomers used Hubble to image and analyze the lensed galaxy with the observatory's Wide Field Camera 3.
The distorted image of the galaxy is repeated several times in the foreground lensing cluster, as is typical of gravitational lenses. The challenge for astronomers was to reconstruct what the galaxy really looked like, were it not distorted by the cluster's funhouse-mirror effect.
Hubble's sharp vision allowed astronomers to remove the distortions and reconstruct the galaxy image as it would normally look. The reconstruction revealed regions of star formation glowing like bright Christmas tree bulbs. These are much brighter than any star-formation region in our Milky Way galaxy.
Through spectroscopy, the spreading out of the light into its constituent colors, the team plans to analyze these star-forming regions from the inside out to better understand why they are forming so many stars.
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Thanks to the presence of a natural “zoom lens” in space, this is a close-up look at brightest distant “magnified” galaxy in the universe known to date. It is one of the most striking examples of gravitational lensing, where the gravitational field of a foreground galaxy bends and amplifies the light of a more distant background galaxy. In this image the light from a distant galaxy, nearly 10 billion light-years away, has been warped into a nearly 90-degree arc of light in the galaxy cluster RCS2 032727-132623. The galaxy cluster lies 5 billion light-years away. The background galaxy’s image is 20 times larger and over three times brighter than typically lensed galaxies. The natural color image was taken in March 2011 with the Hubble Space Telescope’s Wide Field Camera 3. Credit: NASA; ESA; J. Rigby (NASA Goddard Space Flight Center); and K. Sharon (Kavli Institute for Cosmological Physics, University of Chicago)
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The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
|  PASADENA, Calif. -- NASA's solar-powered Juno spacecraft successfully refined its flight path Wednesday with the mission's first trajectory correction maneuver. The maneuver took place on Feb. 1. It is the first of a dozen planned rocket firings that, over the next five years, will keep Juno on course for its rendezvous with Jupiter. "We had a maneuver planned soon after launch but our Atlas V rocket gave us such a good ride we didn't need to make any trajectory changes," said Rick Nybakken, Juno project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It is good to get another first under our belt. This burn couldn't have gone any better." The trajectory correction maneuver, which adjusts the spacecraft's flight path, began at 10:10 a.m. PST (1:10 p.m. EST) on Feb. 1. The Juno spacecraft's thrusters fired for 25 minutes, consumed about 6.9 pounds (3.11 kilograms) of fuel and changed the spacecraft's speed by 3.9 feet, or 1.2 meters, per second. The next big maneuver for Juno will occur in late August of 2012 when Juno executes its first of two deep space maneuvers to set the stage for its Earth flyby – and gravity assist – on its way to Jupiter. Launched on Aug. 5, 2011, Juno is 182 days and 279 million miles (449 million kilometers) into its five-year, 1,740-million-mile (2,800-million-kilometer) journey to Jupiter. Once in orbit, the spacecraft will orbit the planet's poles 33 times and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover to learn more about Jupiter's origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core. Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena. |  PASADENA, Calif. -- A camera aboard one of NASA's twin Gravity Recovery And Interior Laboratory (GRAIL) lunar spacecraft has returned its first unique view of the far side of the moon. MoonKAM, or Moon Knowledge Acquired by Middle school students, will be used by students nationwide to select lunar images for study. GRAIL consists of two identical spacecraft, recently named Ebb and Flow, each of which is equipped with a MoonKAM. The images were taken as part of a test of Ebb's MoonKAM on Jan. 19. The GRAIL project plans to test the MoonKAM aboard Flow at a later date. To view the 30-second video clip, visit: http://www.youtube.com/watch?v=BQd14jmPXEo&feature=player_detailpage In the video, the north pole of the moon is visible at the top of the screen as the spacecraft flies toward the lunar south pole. One of the first prominent geological features seen on the lower third of the moon is the Mare Orientale, a 560-mile-wide (900 kilometer) impact basin that straddles both the moon's near and far side. The clip ends with rugged terrain just short of the lunar south pole. To the left of center, near the bottom of the screen, is the 93-mile-wide (149 kilometer) Drygalski crater with a distinctive star-shaped formation in the middle. The formation is a central peak, created many billions of years ago by a comet or asteroid impact. "The quality of the video is excellent and should energize our MoonKAM students as they prepare to explore the moon," said Maria Zuber, GRAIL principal investigator from the Massachusetts Institute of Technology in Cambridge. The twin spacecraft successfully achieved lunar orbit this past New Year's Eve and New Year's Day. Previously named GRAIL-A and GRAIL-B, the washing machine-sized spacecraft received their new names from fourth graders at the Emily Dickinson Elementary School in Bozeman, Mont., following a nationwide student naming contest. Thousands of fourth- to eighth-grade students will select target areas on the lunar surface and send requests to the GRAIL MoonKAM Mission Operations Center in San Diego. Photos of the target areas will be sent back by the satellites for students to study. The MoonKAM program is led by Sally Ride, America's first woman in space. Her team at Sally Ride Science and undergraduate students at the University of California in San Diego will engage middle schools across the country in the GRAIL mission and lunar exploration. GRAIL is NASA's first planetary mission carrying instruments fully dedicated to education and public outreach. "We have had great response from schools around the country; more than 2,500 signed up to participate so far," Ride said. "In mid-March, the first pictures of the moon will be taken by students using MoonKAM. I expect this will excite many students about possible careers in science and engineering." Launched in September 2011, Ebb and Flow periodically perform trajectory correction maneuvers that, over time, will lower their orbits to near-circular ones with an altitude of about 34 miles (55 kilometers). During their science mission, the duo will answer longstanding questions about the moon and give scientists a better understanding of how Earth and other rocky planets in the solar system formed. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the GRAIL mission for NASA's Science Mission Directorate in Washington. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft. JPL is managed for NASA by the California Institute of Technology in Pasadena. |  PASADENA - A great magnetic bubble surrounds the solar system as it cruises through the galaxy. The sun pumps the inside of the bubble full of solar particles that stream out to the edge until they collide with the material that fills the rest of the galaxy, at a complex boundary called the heliosheath. On the other side of the boundary, electrically charged particles from the galactic wind blow by, but rebound off the heliosheath, never to enter the solar system. Neutral particles, on the other hand, are a different story. They saunter across the boundary as if it weren't there, continuing on another 7.5 billion miles for 30 years until they get caught by the sun's gravity, and sling shot around the star. VIEW THE VIDEO HERE: http://www.youtube.com/watch?v=4SrMwWjKZfU&feature=player_detailpage
There, NASA's Interstellar Boundary Explorer lies in wait for them. Known as IBEX for short, this spacecraft methodically measures these samples of the mysterious neighborhood beyond our home. IBEX scans the entire sky once a year, and every February, its instruments point in the correct direction to intercept incoming neutral atoms. IBEX counted those atoms in 2009 and 2010 and has now captured the best and most complete glimpse of the material that lies so far outside our own system.
The results? It's an alien environment out there: the material in that galactic wind doesn't look like the same stuff our solar system is made of. "We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," says Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "IBEX's observations shed a whole new light on the mysterious zone where the solar system ends and interstellar space begins."
More than just helping to determine the distribution of elements in the galactic wind, these new measurements give clues about how and where our solar system formed, the forces that physically shape our solar system, and even the history of other stars in the Milky Way. In a series of science papers appearing in the Astrophysics Journal on January 31, 2012, scientists report that for every 20 neon atoms in the galactic wind, there are 74 oxygen atoms. In our own solar system, however, for every 20 neon atoms there are 111 oxygen atoms. That translates to more oxygen in any given slice of the solar system than in the local interstellar space.
"Our solar system is different than the space right outside it and that suggests two possibilities," says David McComas the principal investigator for IBEX at the Southwest Research Institute in San Antonio, Texas. "Either the solar system evolved in a separate, more oxygen-rich part of the galaxy than where we currently reside or a great deal of critical, life-giving oxygen lies trapped in interstellar dust grains or ices, unable to move freely throughout space." Either way, this affects scientific models of how our solar system – and life – formed.
Studying the galactic wind also provides scientists with information about how our solar system interacts with the rest of space, which is congruent with an important IBEX goal. Classified as a NASA Explorer Mission -- a class of smaller, less expensive spacecraft with highly focused research objectives -- IBEX's main job is to study the heliosheath, that outer boundary of the solar system's magnetic bubble -- or heliosphere -- where particles from the solar wind meet the galactic wind.
Previous spacecraft have already provided some information about the way the galactic wind interacts with the heliosheath. Ulysses, for one, observed incoming helium as it traveled past Jupiter and measured it traveling at 59,000 miles per hour. IBEX's new information, however, shows the galactic wind traveling not only at a slower speed -- around 52,000 miles per hour -- but from a different direction, most likely offset by some four degrees from previous measurements. Such a difference may not initially seem significant, but it amounts to a full 20% difference in how much pressure the galactic wind exerts on the heliosphere. Measuring the pressure on our heliosphere from the material in the galaxy and from the magnetic fields out there," says Christian, "will help determine the size and shape of our solar system as it travels through the galaxy."
These IBEX measurements also provide information about the cloud of material in which the solar system currently resides. This cloud is called the local interstellar cloud, to differentiate it from the myriad of particle clouds throughout the Milky Way, each traveling at different speeds. The solar system and its heliosphere moved into our local cloud at some point during the last 45,000 years.
Since the older Ulysses observations of the galactic wind speed was in between the speeds expected for the local cloud and the adjacent cloud, researchers thought perhaps the solar system didn't lie smack in the middle of this cloud, but might be at the boundary, transitioning into a new region of space. IBEX's results, however, show that we remain fully in the local cloud, at least for the moment.
"Sometime in the next hundred to few thousand years, the blink of an eye on the timescales of the galaxy, our heliosphere should leave the local interstellar cloud and encounter a much different galactic environment," McComas says.
In addition to providing insight into the interaction between the solar system and its environment, these new results also hold clues about the history of material in the universe. While the big bang initially created hydrogen and helium, only the supernovae explosions at the end of a giant star's life can spread the heavier elements of oxygen and neon through the galaxy. Knowing the amounts of such elements in space can help map how the galaxy has evolved and changed over time.
This set of papers provide many of the first direct measurements of the interstellar medium around us," says McComas. "We've been trying to understand our galaxy for a long time, and with all of these observations together, we are taking a major step forward in knowing what the local part of the galaxy is like."
Voyager 1 could cross out of our solar system within the next few years. By combining the data from several sets of NASA instruments – Ulysses, Voyager, IBEX and others – we are on the precipice of stepping outside and understanding the complex environment beyond our own frontier for the first time.
The Southwest Research Institute developed and leads the IBEX mission with a team of national and international partners. The spacecraft is one of NASA's series of low-cost, rapidly developed missions in the Small Explorers Program. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the program for the agency's Science Mission Directorate.
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| NASA's Interstellar Boundary Explorer (IBEX) has found that there's more oxygen in our solar system than there is in the nearby interstellar material. That suggests that either the sun formed in a different part of the galaxy or that outside our solar system life-giving oxygen lies trapped in dust or ice grains unable to move freely in space. Credit: NASA/Goddard |
For more information about the IBEX mission, go to: › http://www.nasa.gov/ibex
› Additional downloadable media
|  PASADENA - Vital clues about the devastating ends to the lives of massive stars can be found by studying the aftermath of their explosions. In its more than twelve years of science operations, NASA's Chandra X-ray Observatory has studied many of these supernova remnants sprinkled across the Galaxy.
The latest example of this important investigation is Chandra's new image of the supernova remnant known as G350.1+0.3. This stellar debris field is located some 14,700 light years from the Earth toward the center of the Milky Way.
Evidence from Chandra and from ESA's XMM-Newton telescope suggest that a compact object within G350.1+0.3 may be the dense core of the star that exploded. The position of this likely neutron star, seen by the arrow pointing to "neutron star" in the inset image, is well away from the center of the X-ray emission. If the supernova explosion occurred near the center of the X-ray emission then the neutron star must have received a powerful kick in the supernova explosion.
Data from Chandra and other telescopes suggest this supernova remnant, as it appears in the image, is between 600 and 1,200 years old. If the estimated location of the explosion is correct, this means that the neutron star has been moving at a speed of at least 3 million miles per hour since the explosion This is comparable to the exceptionally high speed derived for the neutron star in Puppis A, another neutron star moving at a blistering pace within a supernova remnant. The G350+1+0.3 data provide new evidence that extremely powerful "kicks" may be imparted to neutron stars left behind once the supernova has exploded.
Another intriguing aspect of G350.1+0.3 is its unusual shape. While many supernova remnants are nearly circular, G350.1+0.3 is strikingly asymmetrical as seen in the Chandra data in this image (gold). Infrared data from NASA's Spitzer Space Telescope (light blue) also trace the morphology found by Chandra. Astronomers think that this bizarre shape is due to stellar debris field expanding into a nearby cloud of cold molecular gas.
The age of 600-1200 years puts the explosion that created G350.1+0.3 in the same time frame as other famous supernovas that formed the Crab and SN 1006 supernova remnants. However, it is unlikely that anyone on Earth would have seen the explosion because of the obscuring gas and dust that lies along our line of sight to the remnant.
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| Photo Credit: redits: X-ray: NASA/CXC/SAO/I. Lovchinsky et al; IR: NASA/JPL-Caltech |
These results appeared in the April 10, 2011 issue of The Astrophysical Journal. The scientists on this paper were Igor Lovchinsky and Patrick Slane (Harvard-Smithsonian Center for Astrophysics), Bryan Gaensler (University of Sydney, Australia), Jack Hughes (Rutgers University), Jasmina Lazendic (Monash University Clayton, Australia), Joseph Gelfand (New York University, Abu Dhabi), and Crystal Brogan (National Radio Astronomy Observatory).
|  PARANAL - Using the APEX telescope, a team of astronomers has found the strongest link so far between the most powerful bursts of star formation in the early Universe, and the most massive galaxies found today. The galaxies, flowering with dramatic starbursts in the early Universe, saw the birth of new stars abruptly cut short, leaving them as massive — but passive — galaxies of aging stars in the present day. The astronomers also have a likely culprit for the sudden end to the starbursts: the emergence of supermassive black holes. Astronomers have combined observations from the LABOCA camera on the ESO-operated 12-metre Atacama Pathfinder Experiment (APEX) telescope [1] with measurements made with ESO’s Very Large Telescope, NASA’s Spitzer Space Telescope, and others, to look at the way that bright, distant galaxies are gathered together in groups or clusters. The more closely the galaxies are clustered, the more massive are their halos of dark matter — the invisible material that makes up the vast majority of a galaxy’s mass. The new results are the most accurate clustering measurements ever made for this type of galaxy. The galaxies are so distant that their light has taken around ten billion years to reach us, so we see them as they were about ten billion years ago [2]. In these snapshots from the early Universe, the galaxies are undergoing the most intense type of star formation activity known, called a starburst. By measuring the masses of the dark matter halos around the galaxies, and using computer simulations to study how these halos grow over time, the astronomers found that these distant starburst galaxies from the early cosmos eventually become giant elliptical galaxies — the most massive galaxies in today’s Universe. “This is the first time that we've been able to show this clear link between the most energetic starbursting galaxies in the early Universe, and the most massive galaxies in the present day," explains Ryan Hickox (Dartmouth College, USA and Durham University, UK), the lead scientist of the team. Furthermore, the new observations indicate that the bright starbursts in these distant galaxies last for a mere 100 million years — a very short time in cosmological terms — yet in this brief time they are able to double the quantity of stars in the galaxies. The sudden end to this rapid growth is another episode in the history of galaxies that astronomers do not yet fully understand. “We know that massive elliptical galaxies stopped producing stars rather suddenly a long time ago, and are now passive. And scientists are wondering what could possibly be powerful enough to shut down an entire galaxy’s starburst,” says Julie Wardlow (University of California at Irvine, USA and Durham University, UK), a member of the team. The team’s results provide a possible explanation: at that stage in the history of the cosmos, the starburst galaxies are clustered in a very similar way to quasars, indicating that they are found in the same dark matter halos. Quasars are among the most energetic objects in the Universe — galactic beacons that emit intense radiation, powered by a supermassive black hole at their centre. There is mounting evidence to suggest the intense starburst also powers the quasar by feeding enormous quantities of material into the black hole. The quasar in turn emits powerful bursts of energy that are believed to blow away the galaxy’s remaining gas — the raw material for new stars — and this effectively shuts down the star formation phase. “In short, the galaxies’ glory days of intense star formation also doom them by feeding the giant black hole at their centre, which then rapidly blows away or destroys the star-forming clouds,” explains David Alexander (Durham University, UK), a member of the team.
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The LABOCA camera on the ESO-operated 12-metre Atacama Pathfinder Experiment (APEX) telescope reveals distant galaxies undergoing the most intense type of star formation activity known, called a starburst. This image shows these distant galaxies, found in a region of sky known as the Extended Chandra Deep Field South, in the constellation of Fornax (The Furnace). The galaxies seen by LABOCA are shown in red, overlaid on an infrared view of the region as seen by the IRAC camera on the Spitzer Space Telescope.
By studying how some of these distant starburst galaxies are clustered together, astronomers have found that they eventually become so-called giant elliptical galaxies — the most massive galaxies in today’s Universe.
The galaxies are so distant that their light has taken around ten billion years to reach us, so we see them as they were about ten billion years ago. Because of this extreme distance, the infrared light from dust grains heated by starlight is redshifted into longer wavelengths, and the dusty galaxies are therefore best observed in submillimetre wavelengths of light. The galaxies are thus known as submillimetre galaxies. Photo Credit: ESO
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Notes [1] The 12-metre-diameter APEX telescope is located on the Chajnantor plateau in the foothills of the Chilean Andes. APEX is a pathfinder for ALMA, the Atacama Large Millimeter/submillimeter Array, a revolutionary new telescope that ESO, together with its international partners, is building and operating, also on the Chajnantor plateau. APEX is itself based on a single prototype antenna constructed for the ALMA project. The two telescopes are complementary: for example, APEX can find many targets across wide areas of sky, which ALMA will be able to study in great detail. APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. [2] These distant galaxies are known as submillimetre galaxies. They are very bright galaxies in the distant Universe in which intense star formation occurs. Because of this extreme distance, their infrared light from dust grains heated by starlight is redshifted into longer wavelengths, and the dusty galaxies are therefore best observed in submillimetre wavelengths of light. More informationThis research is presented in a paper to appear in the journal Monthly Notices of the Royal Astronomical Society on 26 January 2012.
The team is composed of Ryan C. Hickox (Dartmouth College, Hanover, USA; Department of Physics, Durham University (DU); STFC Postdoctoral Fellow, UK), J. L. Wardlow (Department of Physics & Astronomy, University of California at Irvine, USA; Department of Physics, DU, UK), Ian Smail (Institute for Computational Cosmology, DU, UK), A. D. Myers (Department of Physics and Astronomy, University of Wyoming, USA), D. M. Alexander (Department of Physics, DU, UK), A. M. Swinbank (Institute for Computational Cosmology, DU, UK), A. L. R. Danielson (Institute for Computational Cosmology, DU, UK), J. P. Stott (Department of Physics, DU, UK), S. C. Chapman (Institute of Astronomy, Cambridge, UK), K. E. K. Coppin (Department of Physics, McGill University, Canada), J. S. Dunlop (Institute for Astronomy, University of Edinburgh, UK), E. Gawiser (Department of Physics and Astronomy, The State University of New Jersey, USA), D. Lutz (Max-Planck-Institut für extraterrestrische Physik, Germany), P. van der Werf (Leiden Observatory, Leiden University, The Netherlands), A. Weiß (Max-Planck-Institut für Radioastronomie, Germany). The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. 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 the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”. ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. |  GREENBELT, Md - When scientists discovered two great swaths of radiation encircling Earth in the 1950s, it spawned over-the-top fears about "killer electrons" and space radiation effects on Earthlings. The fears were soon quieted: the radiation doesn't reach Earth, though it can affect satellites and humans moving through the belts. Nevertheless, many mysteries about the belts – now known as the Van Allen Radiation belts – remain to this day.
Filled with electrons and energetic charged particles, the radiation belts swell and shrink in response to incoming solar energy, but no one is quite sure how. Indeed, what appears to be the same type of incoming energy has been known to cause entirely different responses on different occasions, causing increased particles in one case and particle loss in another. Theories on just what causes the belts to swell or shrink abound, with little hard evidence to distinguish between them. One big question has simply been to determine if, when the belts shrink, particles escape up and out into interplanetary space or down toward Earth. Now, a new study using multiple spacecraft simultaneously has tracked the particles and determined the escape direction for at least one event: up.
"For a long time, it was thought particles would precipitate downward out of the belts," says Drew Turner, a scientist at the University of California, Los Angeles, and first author on a paper on these results appearing onine in Nature Physics on January 29, 2012 date. "But more recently, researchers theorized that maybe particles could sweep outward. Our results for this event are clear: we saw no increase in downward precipitation."
While it may sound like a simple detail, such knowledge is not just esoteric. Indeed, the study of particle losses in the belts has so far provided more mystery and potential theories than concrete information. But understanding the radiation belts – and how they change as particles and energy come in or go out -- is a crucial part of protecting satellites that fly through the region.
The Van Allen belts fit into a larger system that stretches from the sun to Earth. The sun sends out a constant stream of solar wind, not to mention occasional much larger bursts – such as explosions from the sun's atmosphere called coronal mass ejections (CMEs) or shock fronts caused by fast solar winds overtaking slower winds called corotating interaction regions (CIRs).
When these bursts of energy move toward Earth, they can disturb Earth's own magnetic environment, known as the magnetosphere, and create a geomagnetic storm. Sometimes these storms can cause a sudden drop in the radiation belt particles, seemingly emptying the belt in only a few hours. This "drop out" can last for days. What causes the drop out, why it lasts so long, and just how the particles even leave remain unanswered questions.
Solving such a mystery requires numerous spacecraft measuring changes at several points in space to determine whether an event in one place affects an event elsewhere. The Radiation Belt Storm Probes (RBSP), scheduled to launch in August 2012, are specifically geared for such observations, but in the meantime, a team of scientists have brought together two disparate sets of a spacecraft to get an early multipoint view of the radiation belts during an event when the belts experienced a sudden loss of particles.
"We are entering an era where multi-spacecraft are key," says Vassilis Angelopoulos, a space scientist at UCLA, and the principal investigator for THEMIS and a coauthor on the paper. "Being able to unite a fleet of available resources into one study is becoming more of a necessity to turn a corner in our understanding of Earth's environment."
In this case, the team observed a small geomagnetic storm on January 6, 2011 using the three NASA THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, two GOES (Geostationary Operational Environment Satellite), operated by the National Oceanic and Atmospheric Administration (NOAA), and six POES (Polar Operational Environmental Satellite), run jointly by NOAA, and the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) spacecraft.
The THEMIS and GOES spacecraft orbit around Earth's equatorial region, while the POES spacecraft orbit at lower altitude near the poles and travel through the radiation belts several times per day. All are equipped to study the energetic particles in the region. The observations provided an unprecedented view of a geomagnetic storm from numerous viewpoints simultaneously – and the team found unequivocally that particles escaped the radiation belts by streaming out into space, not by raining down toward Earth.
During this storm, electrons moving near the speed of light dropped out for over six hours. In that time period POES saw no increase in electrons escaping downward from the belts. On the other hand, the spacecraft did monitor a low-density patch of the belt that first appeared at the outer edges of the belts and then moved inward. This sequence is consistent with the notion that particles were streaming outward, just as the low density region of cars leaving from the front of a traffic jam moves backward over time as more and more cars are able to move forward and escape.
"This was a very simple storm," says Turner. "It's not an extreme case, so we think it's probably pretty typical of what happens in general and ongoing results from concurrent statistical studies support this."
If, indeed, electrons usually escape the radiation belts by streaming outward, it seems likely that some kind of waves aid and abet their outward motion, enabling them to reach the outer escape boundary. Hammering out this escape mechanism will be one of the jobs for RBSP, says David Sibeck at NASA's Goddard Space Flight Center in Greenbelt, Md., who is NASA's mission scientist for RBSP and project scientist for THEMIS.
"This kind of research is a key to understanding, and eventually predicting, hazardous events in the Earth’s radiation belts," says Sibeck. "It's a great comprehensive example of what we can expect to see throughout the forthcoming RBSP mission."
|  View The Video: http://www.youtube.com/watch?feature=player_detailpage&list=UUOvp8B42Fi3spnO4xFhw00Q&v=S8RJybRihNY GREENBELT, Md - The sun unleashed an X1.8 class flare that began at 1:12 PM ET on January 27, 2012 and peaked at 1:37. The flare immediately caused a strong radio blackout at low-latitudes, which was rated an R3 on NOAA's scale from R1-5. The blackout soon subsided to a minor R1 storm. Models from NASA's Goddard Space Weather Center predict that the CME is traveling at over 1500 miles per second. It does not initially appear to be Earth-directed, but Earth may get a glancing blow.
Initial movies from NASA's Solar Dynamics Observatory (SDO) look as though there was an eruption and coronal mass ejection (CME) associated with the event, and NOAA’s GOES satellite also detected a solar energetic particle (SEP) event a half hour after the flare peak. How these CMEs and SEPs form and evolve, as well as their association with the flare event itself will be studied in the coming hours and days as more data and movies from NASA's SDO, STEREO and SOHO instruments become available.
|  PASADENA - Though generally thought to be quite dry, roughly half of the giant asteroid Vesta is expected to be so cold and to receive so little sunlight that water ice could have survived there for billions of years, according to the first published models of Vesta's average global temperatures and illumination by the sun. "Near the north and south poles, the conditions appear to be favorable for water ice to exist beneath the surface," says Timothy Stubbs of NASA's Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland, Baltimore County. Stubbs and Yongli Wang of the Goddard Planetary Heliophysics Institute at the University of Maryland published the models in the January 2012 issue of the journal Icarus. The models are based on information from telescopes including NASA's Hubble Space Telescope. Vesta, the second-most massive object in the asteroid belt between Mars and Jupiter, probably does not have any significant permanently shadowed craters where water ice could stay frozen on the surface all the time, not even in the roughly 300-mile-diameter (480-kilometer-diameter) crater near the south pole, the authors note. The asteroid isn't a good candidate for permanent shadowing because it is tilted on its axis at about 27 degrees, which is even greater than Earth's tilt of roughly 23 degrees. In contrast, the moon, which does have permanently shadowed craters, is tilted at only about 1.5 degrees. As a result of its large tilt, Vesta has seasons, and every part of the surface is expected to see the sun at some point during Vesta's year. The presence or absence of water ice on Vesta tells scientists something about the tiny world's formation and evolution, its history of bombardment by comets and other objects, and its interaction with the space environment. Because similar processes are common to many other planetary bodies, including the moon, Mercury and other asteroids, learning more about these processes has fundamental implications for our understanding of the solar system as a whole. This kind of water ice is also potentially valuable as a resource for further exploration of the solar system. Though temperatures on Vesta fluctuate during the year, the model predicts that the average annual temperature near Vesta's north and south poles is less than roughly minus 200 degrees Fahrenheit (145 kelvins). That is the critical average temperature below which water ice is thought to be able to survive in the top 10 feet or so (few meters) of the soil, which is called regolith. Near Vesta's equator, however, the average yearly temperature is roughly minus 190 degrees Fahrenheit (150 kelvins), according to the new results. Based on previous modeling, that is expected to be high enough to prevent water from remaining within a few meters of the surface. This band of relatively warm temperatures extends from the equator to about 27 degrees north and south in latitude. "On average, it's colder at Vesta's poles than near its equator, so in that sense, they are good places to sustain water ice," says Stubbs. "But they also see sunlight for long periods of time during the summer seasons, which isn't so good for sustaining ice. So if water ice exists in those regions, it may be buried beneath a relatively deep layer of dry regolith." The modeling also indicates that relatively small surface features, such as craters measuring around 6 miles (10 kilometers) in diameter, could significantly affect the survival of water ice. "The bottoms of some craters could be cold enough on average -- about 100 kelvins -- for water to be able to survive on the surface for much of the Vestan year [about 3.6 years on Earth]," Stubbs explains. "Although, at some point during the summer, enough sunlight would shine in to make the water leave the surface and either be lost or perhaps redeposit somewhere else." So far, Earth-based observations suggest that the surface of Vesta is quite dry. However, the Dawn spacecraft is getting a much closer view. Dawn is investigating the role of water in the evolution of planets by studying Vesta and Ceres, two bodies in the asteroid belt that are considered remnant protoplanets – baby planets whose growth was interrupted when Jupiter formed. Dawn is looking for water using the gamma ray and neutron detector (GRaND) spectrometer, which can identify hydrogen-rich deposits that could be associated with water ice. The spacecraft recently entered a low orbit that is well suited to collecting gamma ray and neutron data. "Our perceptions of Vesta have been transformed in a few months as the Dawn spacecraft has entered orbit and spiraled closer to its surface," says Lucy McFadden, a planetary scientist at NASA Goddard and a Dawn mission co-investigator. "More importantly, our new views of Vesta tell us about the early processes of solar system formation. If we can detect evidence for water beneath the surface, the next question will be is it very old or very young, and that would be exciting to ponder." The modeling done by Stubbs and Wang, for example, relies on information about Vesta's shape. Before Dawn, the best source of that information was a set of images taken by NASA's Hubble Space Telescope in 1994 and 1996. But now, Dawn and its camera are getting a much closer view of Vesta. "The Dawn mission gives researchers a rare opportunity to observe Vesta for an extended period of time, the equivalent of about one season on Vesta," says Stubbs. "Hopefully, we'll know in the next few months whether the GRaND spectrometer sees evidence for water ice in Vesta's regolith. This is an important and exciting time in planetary exploration."
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| Vesta's South Pole Photo Credit: NASA JPL |
Dawn' mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. The asteroid modeling by Stubbs and Wang is an extension of analysis originally applied to the moon and partially funded by the NASA Lunar Science Institute. |  PASADENA, Calif. -- NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, shipped to Vandenberg Air Force Base, Calif., on Tuesday, to be mated to its Pegasus launch vehicle. The observatory will detect X-rays from objects ranging from our sun to giant black holes billions of light-years away. It is scheduled to launch March 14 from an aircraft operating out of Kwajalein Atoll in the Marshall Islands. "The NuSTAR mission is unique because it will be the first NASA mission to focus X-rays in the high-energy range, creating the most detailed images ever taken in this slice of the electromagnetic spectrum," said Fiona Harrison, the mission's principal investigator at the California Institute of Technology in Pasadena, Calif. The observatory shipped from Orbital Sciences Corporation in Dulles, Va., where the spacecraft and science instrument were integrated. It is scheduled to arrive at Vandenberg on Jan. 27, where it will be mated to the Pegasus, also built by Orbital, on Feb. 17. The mission will be launched from the L-1011 "Stargazer" aircraft, which will take off near the equator from Kwajalein Atoll in the Pacific. NuSTAR and its Pegasus will fly from Vandenberg to Kwajalein attached to the underside of the L-1011, and are scheduled to arrive on March 7. On launch day, after the airplane arrives at the planned drop site over the ocean, the Pegaus will drop from the L-1011 and carry NuSTAR to an orbit around Earth. "NuSTAR is an engineering achievement, incorporating state-of-the-art high-energy X-ray mirrors and detectors that will enable years of astronomical discovery," said Yunjin Kim, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena. NuSTAR's advanced telescope consists of two sets of 133 concentric shells of mirrors, which were shaped from flexible glass similar to that found in laptop screens. Because X-rays require large focusing distances, or focal lengths, the telescope has a lengthy 33-foot (10-meter) mast, which will unfold a week after launch. These and other advances in technology will enable NuSTAR to explore the cosmic world of high-energy X-rays with much improved sensitivity and resolution over previous missions. During its two-year primary mission, NuSTAR will map the celestial sky in X-rays, surveying black holes, mapping supernova remnants, and studying particle jets travelling away from black holes near the speed of light. NuSTAR also will probe the sun, looking for microflares theorized to be on the surface that could explain how the sun's million-degree corona, or atmosphere, is heated. It will even test a theory of dark matter, the mysterious substance making up about one-quarter of our universe, by searching the sun for evidence of a hypothesized dark matter particle. "NuSTAR will provide an unprecedented capability to discover and study some of the most exotic objects in the universe, from the corpses of exploded stars in the Milky Way to supermassive black holes residing in the hearts of distant galaxies," said Lou Kaluzienski, NuSTAR program scientist at NASA Headquarters in Washington.
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| NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, mission is seen here being lowered into its shipping container at Orbital Sciences Corporation in Dulles, Va. Image credit: NASA/JPL-Caltech/Orbital |
NuSTAR is a small-explorer mission managed by JPL for NASA's Science Mission Directorate. The spacecraft was built by Orbital Sciences Corporation. Its instrument was built by a consortium including Caltech, JPL, Columbia University, New York, N.Y., NASA's Goddard Space Flight Center in Greenbelt, Md., the Danish Technical University in Denmark, the University of California, Berkeley, and ATK-Goleta. NuSTAR will be operated by U.C. Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA. |
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