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  • richardmitnick 7:49 am on August 24, 2016 Permalink | Reply
    Tags: , NASA Goddard,   

    From Goddard: “NASA Establishes Contact With STEREO Mission” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    Aug. 22, 2016
    Karen C. Fox
    karen.c.fox@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    NASA/STEREO spacecraft
    NASA/STEREO spacecraft

    2
    On Aug. 21, 2016, NASA reestablished contact with the sun-watching STEREO-B spacecraft, after communications were lost in October 2014. STEREO-B is one of two spacecraft of the Solar Terrestrial Relations Observatory mission, which over the course of their lifetime have viewed the sun from vantage points such as the ones shown here, on the other side of the sun from Earth. This graphic shows the positions of the two STEREO spacecraft and their orbits in relation to Earth, Venus, Mercury and the sun. Credits: NASA

    On Aug. 21, 2016, contact was reestablished with one of NASA’s Solar Terrestrial Relations Observatories, known as the STEREO-B spacecraft, after communications were lost on Oct. 1, 2014. Over 22 months, the STEREO team has worked to attempt contact with the spacecraft. Most recently, they have attempted a monthly recovery operation using NASA’s Deep Space Network, or DSN, which tracks and communicates with missions throughout space.

    The DSN established a lock on the STEREO-B downlink carrier at 6:27 p.m. EDT. The downlink signal was monitored by the Mission Operations team over several hours to characterize the attitude of the spacecraft and then transmitter high voltage was powered down to save battery power. The STEREO Missions Operations team plans further recovery processes to assess observatory health, re-establish attitude control, and evaluate all subsystems and instruments.

    Communications with STEREO-B were lost during a test of the spacecraft’s command loss timer, a hard reset that is triggered after the spacecraft goes without communications from Earth for 72 hours. The STEREO team was testing this function in preparation for something known as solar conjunction, when STEREO-B’s line of sight to Earth – and therefore all communication – was blocked by the sun.

    STEREO-A continues to work normally.

    For more on STEREO: http://www.nasa.gov/stereo

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard campus
    NASA/Goddard Campus
    NASA image

     
  • richardmitnick 3:57 pm on August 15, 2016 Permalink | Reply
    Tags: NASA Goddard, ,   

    From Goddard: “NASA’s Van Allen Probes Catch Rare Glimpse of Supercharged Radiation Belt” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    Aug. 15, 2016
    Lina Tran
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Our planet is nestled in the center of two immense, concentric doughnuts of powerful radiation: the Van Allen radiation belts, which harbor swarms of charged particles that are trapped by Earth’s magnetic field. On March 17, 2015, an interplanetary shock – a shockwave created by the driving force of a coronal mass ejection, or CME, from the sun – struck Earth’s magnetic field, called the magnetosphere, triggering the greatest geomagnetic storm of the preceding decade.

    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase
    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase

    And NASA’s Van Allen Probes were there to watch the effects on the radiation belts.

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    Artist concept of accelerated electrons circulating in Earth’s Van Allen radiation belts. Credits: NASA’s Goddard Space Flight Center; Tom Bridgman, animator

    NASA Van Allen Probes


    On March 17, 2015, an interplanetary shock – a shockwave created by the driving force of a coronal mass ejection, or CME, from the sun – struck the outermost radiation belt, triggering the greatest geomagnetic storm of the preceding decade. NASA’s Van Allen Probes were there to watch it. Credits: NASA’s Goddard Space Flight Center; Genna Duberstein, producer

    One of the most common forms of space weather, a geomagnetic storm describes any event in which the magnetosphere is suddenly, temporarily disturbed. Such an event can also lead to change in the radiation belts surrounding Earth, but researchers have seldom been able to observe what happens. But on the day of the March 2015 geomagnetic storm, one of the Van Allen Probes was orbiting right through the belts, providing unprecedentedly high-resolution data from a rarely witnessed phenomenon. A paper on these observations was published in the Journal of Geophysical Research on Aug. 15, 2016.

    Researchers want to study the complex space environment around Earth because the radiation and energy there can impact our satellites in a wide variety of ways – from interrupting onboard electronics to increasing frictional drag to disrupting communications and navigation signals.

    “We study radiation belts because they pose a hazard to spacecraft and astronauts,” said David Sibeck, the Van Allen Probes mission scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved with the paper. “If you knew how bad the radiation could get, you would build a better spacecraft to accommodate that.”

    Studying the radiation belts is one part of our efforts to monitor, study and understand space weather. NASA launched the twin Van Allen Probes in 2012 to understand the fundamental physical processes that create this harsh environment so that scientists can develop better models of the radiation belts. These spacecraft were specifically designed to withstand the constant bombardment of radiation in this area and to continue to collect data even under the most intense conditions. A set of observations on how the radiation belts respond to a significant space weather storm, from this harsh space environment, is a goldmine.

    The recent research describes what happened: The March 2015 storm was initiated by an interplanetary shock hurtling toward Earth – a giant shockwave in space set off by a CME, much like a tsunami is triggered by an earthquake.

    Swelling and shrinking in response to such events and solar radiation, the Van Allen belts are highly dynamic structures within our planet’s magnetosphere. Sometimes, changing conditions in near-Earth space can energize electrons in these ever-changing regions. Scientists don’t yet know whether energization events driven by interplanetary shocks are common. Regardless, the effects of interplanetary shocks are highly localized events – meaning if a spacecraft is not precisely in the right place when a shock hits, it won’t register the event at all. In this case, only one of the Van Allen Probes was in the proper position, deep within the magnetosphere – but it was able to send back key information.

    The spacecraft measured a sudden pulse of electrons energized to extreme speeds – nearly as fast as the speed of light – as the shock slammed the outer radiation belt. This population of electrons was short-lived, and their energy dissipated within minutes. But five days later, long after other processes from the storm had died down, the Van Allen Probes detected an increased number of even higher energy electrons. Such an increase so much later is a testament to the unique energization processes following the storm.

    “The shock injected – meaning it pushed – electrons from outer regions of the magnetosphere deep inside the belt, and in that process, the electrons gained energy,” said Shri Kanekal, the deputy mission scientist for the Van Allen Probes at Goddard and the leading author of a paper on these results.

    Researchers can now incorporate this example into what they already know about how electrons behave in the belts, in order to try to understand what happened in this case – and better map out the space weather processes there. There are multiple ways electrons in the radiation belts can be energized or accelerated: radially, locally or by way of a shock. In radial acceleration, electrons are carried by low-frequency waves towards Earth. Local acceleration describes the process of electrons gaining energy from relatively higher frequency waves as the electrons orbit Earth. And finally, during shock acceleration, a strong interplanetary shock compresses the magnetosphere suddenly, creating large electric fields that rapidly energize electrons.

    Scientists study the different processes to understand what role each process plays in energizing particles in the magnetosphere. Perhaps these mechanisms occur in combination, or maybe just one at a time. Answering this question remains a major goal in the study of radiation belts – a difficult task considering the serendipitous nature of the data collection, particularly in regard to shock acceleration.

    Additionally, the degree of electron energization depends on the process that energizes them. One can liken the process of shock acceleration, as observed by the Van Allen Probe, to pushing a swing.

    “Think of ‘pushing’ as the phenomenon that’s increasing the energy,” Kanekal said. “The more you push a swing, the higher it goes.” And the faster electrons will move after a shock.

    In this case, those extra pushes likely led to the second peak in high-energy electrons. While electromagnetic waves from the shock lingered in the magnetosphere, they continued to raise the electrons’ energy. The stronger the storm, the longer such waves persist. Following the March 2015 storm, resulting electromagnetic waves lasted several days. The result: a peak in electron energy measured by the Van Allen Probe five days later.

    This March 2015 geomagnetic storm was one of the strongest yet of the decade, but it pales in comparison to some earlier storms. A storm during March 1991 was so strong that it produced long-lived, energized electrons that remained within the radiation belts for multiple years. With luck, the Van Allen Probes may be in the right position in their orbit to observe the radiation belt response to more geomagnetic storms in the future. As scientists gather data from different events, they can compare and contrast them, ultimately helping to create robust models of the little-understood processes occurring in these giant belts.

    The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, built and operates the Van Allen Probes for NASA’s Heliophysics Division in the Science Mission Directorate. The Van Allen Probes are the second mission in NASA’s Living With a Star program, an initiative managed by Goddard and focused on aspects of the sun-Earth system that directly affect human lives and society.

    Related Links

    Van Allen Probes Mission Overview
    NASA’s Van Allen Probes Spot an Impenetrable Barrier in Space
    NASA’s Van Allen Probes Revolutionize View of Radiation Belts

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 12:26 pm on August 12, 2016 Permalink | Reply
    Tags: , , , NASA Goddard, , OSIRIS-REx Laser Altimeter (OLA)   

    From Goddard: “NASA to Map Asteroid Bennu from the Ground Up” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    Aug. 11, 2016
    Sarah Schlieder
    sarah.schlieder@nasa.gov
    NASA’s Goddard Space Flight Center in Greenbelt, Maryland

    1
    The OSIRIS-REx Laser Altimeter (OLA), contributed by the Canadian Space Agency (CSA), will create 3-D maps of asteroid Bennu to help the mission team select a sample collection site. NASA’s OSIRIS-REx spacecraft will travel to the near-Earth asteroid Bennu and bring at least a 60-gram (2.1-ounce) sample back to Earth for study. Credit: NASA/Goddard/Debbie McCallum. phys.org

    How do you study the topography of an asteroid millions of miles away? Map it with a robotic cartographer!

    NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx, will launch in September 2016 and travel to a near-Earth asteroid known as Bennu to harvest a sample of surface material and return it to Earth for study.

    NASA OSIRIS-REx Spacecraft
    NASA OSIRIS-REx Spacecraft

    But before the science team can select a sample site, it needs to know a little something about the asteroid’s topography.

    The OSIRIS-REx Laser Altimeter, or OLA, is provided by the Canadian Space Agency and will be used to create three-dimensional global topographic maps of Bennu and local maps of candidate sample sites.

    “OLA will measure the asteroid’s topography and shape in a detail that is unprecedented compared to other asteroid missions,” said Michael Daly, OLA instrument scientist at York University in Toronto, Canada. ” This 3-D shape will be the foundational dataset for the other instruments.”

    Think of your favorite computer animated movie. The characters and environment are colored and shaded in such a way that they look almost lifelike. But all of those details need a 3-D shape in order to take form. The same is true for the detailed data gathered by OSIRIS-REx’s instruments.

    To create these 3-D models, OLA uses LIDAR, which stands for light detection and ranging. LIDAR is similar to radar, but uses light instead of radio waves to measure distance. OLA will emit infrared laser pulses toward the surface of Bennu as the spacecraft moves around the asteroid. The laser pulses reflect back from the surface to a detector. The team will measure the time difference between outgoing and incoming pulses to calculate the distance between the spacecraft and Bennu.

    LIDAR has been used on prior spacecraft, including the Mars Global Surveyor and the Lunar Reconnaissance Orbiter. Those laser altimeters are fixed to the spacecraft, meaning that the laser pulse will only travel in the direction that the spacecraft is pointing. This can limit the coverage and spatial resolution of their topographic maps. So, while they have generated a vast amount of data, fixed LIDAR are not ideal for missions where the data must be gathered quickly.

    “OLA is the first scanning LIDAR to fly on a planetary mission,” said Beau Bierhaus, an OLA team member at Lockheed Martin. “Because the LIDAR can articulate independently of the spacecraft, the LIDAR provides improved operational flexibility, and more importantly, much greater spatial coverage and resolution.”


    The OSIRIS-REx Laser Altimeter (OLA) will provide a three-dimenional map of asteroid Bennu’s shape, which will allow scientists to understand the context of the asteroid’s geography and the sample location. OLA is provided by the Canadian Space Agency in exchange for Canadian ownership of a portion of the returned asteroid sample.
    Credits: Credit: NASA’s Goddard Space flight Center/Katrina Jackson
    This video is public domain and can be downloaded from the Scientific Visualization Studio.

    OLA is expected to thoroughly map Bennu with about 6 billion measurements of the asteroid’s surface, which measures about one-third of a mile (one-half kilometer) in diameter. In comparison, the laser altimeter on the Lunar Reconnaissance Orbiter has received more than 6.8 billion measurements of the surface of the moon, which has a diameter of about 2,159 miles (3,500 kilometers).

    The fundamental data of the asteroid’s shape and topography that OLA will provide are essential for several key phases during the mission.

    The science team will use the high-resolution topographic data, in conjunction with camera images and on-board navigation algorithms, to navigate around the asteroid and guide the spacecraft to the selected sample site.

    “We’re measuring topography down to one centimeter,” said Olivier Barnouin, the Altimetry Working Group lead at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “We’re looking at an asteroid at a scale that no other mission has before. We don’t want to be off in some unknown area during sample acquisition.”

    The three-dimensional maps will also give geologic context to the returned asteroid sample. Just as geologists on Earth document where they collect their samples in the field on topographic maps, OLA will allow the science team to take their measurements and observations of the collected sample and apply them to their broader understanding of Bennu.

    OLA will also allow the science team to study how regolith, or loose surface material, behaves in a microgravity environment. Scientists have done similar studies on the moon and Mars, but unlike Bennu, these bodies have relatively high gravity.

    “What happens on asteroids is that you take that gravity dial and turn it way down,” Bierhaus said. “The dynamics of how regolith moves on the surface of the asteroid are foreign to us. OLA data will give us a greater understanding of how granular material behaves in space.”

    This understanding is especially important for future asteroid missions. Scientists will need to know how regolith behaves in micro-gravity environments if we want to send astronauts to an asteroid someday to collect samples.

    “Collaborating on this project reminds us of the unique relationship between Canada and the United States,” said Daly. “It provides both countries access to additional technological expertise and people that they would not otherwise have.”

    Goddard will provide overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Dante Lauretta is the mission’s principal investigator at the University of Arizona. Lockheed Martin Space Systems in Denver built the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency’s Science Mission Directorate in Washington.

    For more information about OSIRIS-REx, visit:

    http://www.nasa.gov/osiris-rex

    http://www.asteroidmission.org

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 2:25 pm on August 9, 2016 Permalink | Reply
    Tags: , NASA Goddard,   

    From Goddard: “IRIS Spots Plasma Rain on Sun’s Surface” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    [This post is dedicated to D.O., the family rocket scientist and gourmet cook. I hope he sees it.]

    Aug. 5, 2016
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    No image caption. No image credit.

    On July 24, 2016, NASA’s Interface Region Imaging Spectrograph, or IRIS, captured a mid-level solar flare: a sudden flash of bright light on the solar limb – the horizon of the sun – as seen at the beginning of this video. Solar flares are powerful explosions of radiation. During flares, a large amount of magnetic energy is released, heating the sun’s atmosphere and releasing energized particles out into space. Observing flares such as this helps the IRIS mission study how solar material and energy move throughout the sun’s lower atmosphere, so we can better understand what drives the constant changes we can see on our sun.

    NASA IRIS spacecraft
    NASA/IRIS


    Credits: NASA’s Goddard Space Flight Center; Joy Ng, producer/IRIS/Lockheed Martin Solar and Astrophysics Laboratory

    As the video continues, solar material cascades down to the solar surface in great loops, a flare-driven event called post-flare loops or coronal rain. This material is plasma, a gas in which positively and negatively charged particles have separated, forming a superhot mix that follows paths guided by complex magnetic forces in the sun’s atmosphere. As the plasma falls down, it rapidly cools – from millions down to a few tens of thousands of kelvins. The corona is much hotter than the sun’s surface; the details of how this happens is a mystery that scientists continue to puzzle out. Bright pixels that appear at the end of the video aren’t caused by the solar flare, but occur when high-energy particles bombard IRIS’s charge-coupled device camera – an instrument used to detect photons.

    Related Link

    IRIS mission overview

    3
    This image of a sunspot, taken by NASA’s Transition Region and Coronal Explorer (TRACE) in Sept. 2000, showing the bright emission of the gas at about 1 million degrees, with the cooler material around 10,000 degrees showing up as dark, absorbing structures. NASA/TRACE

    4
    NASA/TRACE

    Tracking the complex processes within these layers of the solar atmosphere requires instrument and modeling capabilities that are within technological reach for the first time. IRIS is the first mission designed to simultaneously observe the range of temperatures specific to the chromosphere and transition region at very high spatial and temporal resolution — going beyond earlier missions that were lower resolution or did not cover a wide range of temperatures.

    IRIS also draws on state of the art computer modeling sophisticated enough to deal with the complexity of this area. In combination, IRIS’s resolution, wide temperature coverage and computer modeling will enable scientists to map plumes of solar material as they move throughout the region and to pinpoint where in their travels they gain energy and heat.

    The mission’s general science objectives are to answer the following questions:

    Which types of non-thermal energy dominate in the chromosphere and beyond?

    How does the chromosphere regulate mass and energy supply to the corona and heliosphere?

    How do magnetic flux and matter rise through the lower atmosphere and what role does flux emergence play in flares and mass ejections?

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 11:45 am on August 1, 2016 Permalink | Reply
    Tags: NASA Goddard, NASA Solar Probe Plus   

    From Goddard: “NASA’s Solar Probe Plus Mission Moves One Step Closer to Launch” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    July 29, 2016
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    NASA’s Solar Probe Plus – the first mission that will fly into sun’s upper atmosphere and “touch” the sun – has passed a design review, an important milestone leading to its anticipated summer 2018 launch.

    NASA/SPP Solar Probe Plus
    NASA/SPP Solar Probe Plus

    The successful review means the mission may now transition from formulation and design to final assembly and implementation. The spacecraft, as it appears in the image, currently includes the primary structure and propulsion system. Over the next phase of the mission, engineers at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland – which manages the mission and is building the spacecraft – will finish assembly and install the rest of the spacecraft systems and science instruments.

    1
    Engineers at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, prepare the developing Solar Probe Plus spacecraft for thermal vacuum tests that simulate conditions in space. Today the spacecraft includes the primary structure and its propulsion system; still to be installed over the next several months are critical systems such as power, communications and thermal protection, as well as science instruments. Credits: NASA/JHUAPL

    Solar Probe Plus is slated to launch during a 20-day window that opens July 31, 2018. The spacecraft will collect data on the mechanisms that heat the corona and accelerate the solar wind, a constant flow of charged particles from the sun. These are two processes with fundamental roles in the complex interconnected system linking the sun and near-Earth space – a system that can drive changes in our space weather and impact our satellites. Solar Probe Plus is part of NASA’s Living With a Star program, an initiative focused on aspects of the sun-Earth system that directly affect human lives and society. The program is managed by NASA’s Goddard Spaceflight Center in Greenbelt, Maryland.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 3:16 pm on July 26, 2016 Permalink | Reply
    Tags: , , NASA Goddard, NASA Team Begins Testing of a New-Fangled Optic, Variant of Fresnel Zone Plate   

    From Goddard: “NASA Team Begins Testing of a New-Fangled Optic” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    July 26, 2016
    Lori Keesey
    NASA’s Goddard Space Flight Center

    It’s an age-old astronomical truth: To resolve smaller and smaller physical details of distant celestial objects, scientists need larger and larger light-collecting mirrors. This challenge is not easily overcome given the high cost and impracticality of building and — in the case of space observatories — launching large-aperture telescopes.

    2
    This image shows how the photon sieve brings red laser light to a pinpoint focus on its optical axis, but produces exotic diffraction patterns when viewed from the side. Credits: NASA/W. Hrybyk

    However, a team of scientists and engineers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has begun testing a potentially more affordable alternative called the photon sieve. This new-fangled telescope optic could give scientists the resolution they need to see finer details still invisible with current observing tools – a jump in resolution that could help answer a 50-year-old question about the physical processes heating the sun’s million-degree corona.

    Although potentially useful at all wavelengths, the team specifically is developing the photon sieve for studies of the sun in the ultraviolet, the wavelengths needed to disentangle the coronal heating mystery. With support from Goddard’s Research and Development program, the team has fabricated three sieves and now plans to begin testing to see if it can withstand the rigors of operating in space — milestones achieved in less than a year. “This is already a success,” said Doug Rabin, who is leading the R&D initiative.

    3
    This drawing shows the differences between Fresnel zone plates and the photon sieve. The latter is dotted with millions of precisely machined holes. Credits: NASA

    Variant of Fresnel Zone Plate

    The optic is a variant of something called a Fresnel zone plate. Rather than focusing light as most telescopes do through refraction or reflection, Fresnel plates cause light to diffract — a phenomenon that happens when light travels through a thin opening and then spreads out. This causes the light waves on the other side to reinforce or cancel each other out in precise patterns.

    Fresnel plates consist of a tightly spaced set of rings, alternatingly transparent or opaque. Light travels through the spaces between the opaque zones, which are precisely spaced so that the diffracted light overlaps and focuses at a specific point, creating an image that can be recorded by a solid-state sensor.

    The photon sieve operates largely the same. However, the sieve is dotted with millions of holes precisely placed on silicon in a circular pattern that takes the place of conventional Fresnel zones.

    The team wants to build a photon sieve at least three feet, or one meter, in diameter — a size they think could achieve up to 100 times better angular resolution in the ultraviolet than NASA’s high-resolution space telescope, the Solar Dynamics Observatory.

    “For more than 50 years, the central unanswered question in solar coronal science has been to understand how energy transported from below is able to heat the corona,” Rabin said. “Current instruments have spatial resolutions about 100 times larger than the features that must be observed to understand this process.”

    Rabin believes his team is well along the way in building an optic that can help answer the question.

    Millions of Holes

    In just a few months’ time, his team built three devices measuring three inches wide — five times larger than the initial 17-millimeter optic developed four years ago under a previous R&D-funded effort. Each device contains 16 million holes whose sizes and locations were determined by team member Adrian Daw. Another team member, Kevin Denis, then etched the holes in a silicon wafer to Daw’s exacting specifications using a fabrication technique called photolithography.

    Team members Anne-Marie Novo-Gradac and John O’Neill have acquired optical images with the new photon sieves, while Tom Widmyer and Greg Woytko have prepared them for vibration testing to make sure they can survive harsh g-forces encountered during launch.

    “This testing is to prove that the photon sieve will work as well as theory predicts,” Rabin said. Although the team has already accomplished nearly all the goals it set forth when work began late last year, Rabin believes the team can enlarge the optics by a factor of two before the end of the fiscal year.

    Formation-Flying CubeSat

    But the work likely won’t end there. In the nearer term, Rabin believes his team can mature the technology for a potential sounding-rocket demonstration. In the longer term, he and team member Joe Davila envision the optic flying on a two-spacecraft formation-flying CubeSat-type mission designed specifically to study the sun’s corona.

    “The scientific payoff is a feasible and cost-effective means of achieving the resolution necessary to answer a key problem in solar physics,” he said.

    For more technology news, go to: http://gsfctechnology.gsfc.nasa.gov/newsletter/Current.pdf

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 12:56 pm on July 14, 2016 Permalink | Reply
    Tags: , NASA Goddard, , NASA REXIS   

    From Goddard: “NASA Instrument to Use X-Rays to Map an Asteroid” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    July 12, 2016
    Sarah Schlieder
    sarah.schlieder@nasa.gov
    NASA’s Goddard Space Flight Center in Greenbelt, Md.

    1
    REXIS. No image caption. No image credit.

    NASA’s OSIRIS-REx spacecraft will launch September 2016 and travel to the near-Earth asteroid Bennu to harvest a sample of surface material and return it to Earth for study. But before the science team selects a sample site, they can find out a bit about Bennu’s elemental make-up.

    NASA OSIRIS-Rex Spacecraft
    NASA/OSIRIS-Rex Spacecraft

    To determine the composition of Bennu’s surface, the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) team equipped the spacecraft with an instrument that will identify which elements are present on the asteroid and measure their abundance.


    NASAs OSIRIS-REx mission launches in September 2016 and plans to return a sample of asteroid Bennu to Earth in 2023.
    Access mp4 video here .

    The Regolith X-ray Imaging Spectrometer, or REXIS can image X-ray emission from Bennu in order to provide an elemental abundance map of the asteroid’s surface.

    “REXIS is different from the other imaging instruments on OSIRIS-REx because we’re going to determine what Bennu is made of at the level of individual atomic elements,” said Richard Binzel, REXIS principal investigator and instrument scientist at the Massachusetts Institute of Technology (MIT), Cambridge. “We’re sniffing the atoms on the surface of Bennu.”

    To do that, REXIS gets a little help from the sun. Atoms on Bennu’s surface absorb incoming solar X-rays that are emitted along with the solar wind. This causes electrons in the atom to move to a higher energy level. However, because these excited electrons are unstable, they quickly de-excite and drop back down to their original energy level and emit their own X-ray in turn. This process is known as fluorescence.

    “You have all this energy coming in, and it kicks electrons up to the next energy level, but the electrons quickly decay back down and emit X-rays of precisely that same energy,” said Josh Grindlay, REXIS co-principal investigator and deputy instrument scientist at Harvard University, Cambridge, Massachusetts. “The net result is a glowing surface on Bennu.”

    The energies of the re-emitted X-rays are characteristic of the elements from which they came. Elements absorb and re-emit X-rays at different, specific energies. The energies that the science team will see glowing at Bennu’s surface will tell the researchers which elements are present.

    In order to map these emitted X-rays, REXIS is fitted with what’s known as a coded aperture mask. The mask consists of a pattern of pinholes that, when X-rays shine through, creates a shadow pattern on REXIS’ detector.

    Imagine sitting in your bedroom at night and a car drives by. The headlights cast a pattern of light and shadow on the walls. As the car moves, so do the shadows. In REXIS’ case, it’s the spacecraft that moves over the asteroid surface. The changing shadow patterns allow the team to identify any particular bright spots on Bennu that might be especially abundant in a certain element.

    REXIS was selected as a Student Collaboration Experiment for the OSIRIS-REx mission. Built by a team from MIT and Harvard, students will perform data analysis of REXIS as part of their coursework.

    “This has been an amazing experience for the students,” said Rebecca Masterson, REXIS co-principal investigator and instrument manager at MIT. “They get to see how a mission evolves and what it takes to get to the point of launch. They’re getting to see how an idea goes from conception to completion and actually play a role in its success.”

    More than 100 students will have been involved in REXIS upon the completion of the OSIRIS-REx mission.

    “Even though OSIRIS-REx hasn’t left the ground, I think REXIS is already a success,” said David Miller, NASA’s chief technologist and a former REXIS team lead at MIT. “We’ve inspired so many students. They are our next generation of space scientists and engineers, and they’ve already had a profound impact on our abilities to go further and explore deep space.”

    Goddard provides overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Dante Lauretta is the mission’s principal investigator at the University of Arizona. Lockheed Martin Space Systems in Denver built the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency’s Science Mission Directorate in Washington.

    For more information about OSIRIS-REx, visit:

    http://www.nasa.gov/osiris-rex

    http://www.asteroidmission.org

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 8:34 pm on June 29, 2016 Permalink | Reply
    Tags: , , , NASA Goddard,   

    From Goddard: “NASA’s OSIRIS-REx Gears up for 3-D Mapping on the Fly” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    June 29, 2016
    Elizabeth Zubritsky
    elizabeth.a.zubritsky@nasa.gov
    NASA’S Goddard Space Flight Center, Greenbelt, Maryland

    Scheduled for launch on Sept. 8, NASA’s OSIRIS-REx mission will travel to an asteroid, study it and return a sample to Earth for analysis. All of these goals depend on accurate mapping of the target, Bennu, so the team is gearing up for the challenges of cartography of an asteroid.

    1
    Bennu with OSIRIS-REx

    NASA OSIRIS-Rex Spacecraft
    NASA OSIRIS-Rex Spacecraft

    “Mapping of Bennu is necessary, of course, but it’s also an exciting and technically interesting aspect of the mission,” said Ed Beshore, OSIRIS-REx deputy principal investigator at the University of Arizona in Tucson. The mission is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    The maps will be generated using information gathered by the five instruments aboard OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer. Upon its rendezvous with Bennu, the spacecraft will spend a year surveying the asteroid for both scientific and operations purposes – including searching for plumes of material coming from the asteroid, measuring non-gravitational forces acting on Bennu, and identifying the best location to collect a sample.

    Most of the mapping work will be done during this survey phase. The team will document the shape of the asteroid, generate a suite of top-level maps, and perform reconnaissance on the final few candidates on the list of possible sampling sites. The reconnaissance maps will be so detailed that team members will be able to spot individual pebbles measuring about three-fourths of an inch (2 centimeters) across – roughly the maximum size of material that the sampling head can collect.

    “Everything the spacecraft learns will be woven together like a tapestry to tell the story of Bennu,” said Kevin Walsh, an OSIRIS-REx co-investigator at the Southwest Research Institute in Boulder, Colorado.

    In the meantime, the groundwork for mapping is being laid.

    The underlying framework is a 3-D shape model. This step is crucial because asteroids, unlike planets and moons, aren’t nice and round. They tend to be bumpy and irregular, often like potatoes. Bennu is more of a lumpy ball that gets thicker around the middle – a shape astronomers compare to a spinning top.

    This rough shape was determined from radar studies conducted from Earth since the asteroid’s discovery in 1999. After OSIRIS-REx surveys Bennu, a new model that captures the subtleties of the asteroid’s shape will be developed.

    For the global maps, information from the spacecraft’s instruments will be overlaid on the shape model. The team plans to incorporate some of these 3-D maps as a routine part of mission-critical operations. Three top-level operations maps are planned: one to evaluate which areas are safe enough to allow the spacecraft to move close to the asteroid, one to determine where the sampling arm can make good contact with the surface to perform its touch-and-go maneuver, and one to indicate where to find the material most suitable for sampling. A fourth top-level map will evaluate how scientifically valuable different regions of the asteroid are.

    “These four maps will be the key to selecting a sampling site,” said Lucy Lim, OSIRIS-REx assistant project scientist at Goddard. “To make sure the map-making goes smoothly once we arrive at Bennu, we started developing the algorithms and practicing all the steps long before launch.”

    Preparations also include establishing map conventions, such as specifying which of Bennu’s poles is north. The team based this decision on the direction of the asteroid’s rotation – a choice that fits with guidelines from the International Astronomical Union. Bennu spins in the direction opposite to Earth, so the asteroid’s poles are reversed compared to our planet’s poles.

    The location of Bennu’s prime meridian – zero degrees longitude – also has been chosen. It runs through a large bump seen on the preliminary shape model. Later, this selection will be refined, or perhaps redefined, depending on what Bennu looks like up close.

    “We make as many decisions about mapping as we can ahead of time, because the work will be intensive once we arrive at Bennu,” said Daniella DellaGiustina, the OSIRIS-REx lead image processing scientist at the University of Arizona. “But we have to allow some flexibility to make changes later, if we need to.”

    Navigation is another special consideration when mapping Bennu. Because the asteroid is so small, its gravitational force is very weak, accounting for only about half of the total force the orbiting spacecraft will feel when it’s close to Bennu. The other half will come from pressure due to sunlight on the surface of the spacecraft.

    The pressure exerted by sunlight is difficult to model, so the navigation team will have to perform frequent updates – perhaps daily. The instrument teams will have to adjust quickly to the changes in plans.

    “This won’t be an orbit the way we usually think of one – that’s how important this force will be,” said Michael Moreau, OSIRIS-REx flight dynamics system manager at Goddard. “OSIRIS-REx is going to take this work to a new level at Bennu.”

    NASA Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Dante Lauretta is the mission’s principal investigator at the University of Arizona, Tucson. Lockheed Martin Space Systems in Denver is building the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency’s Science Mission Directorate in Washington.

    Launch management is the responsibility of NASA’s Launch Services Program at the Kennedy Space Center in Florida.

    OSIRIS-Rex instruments

    NASA OSIRIS REX OLA
    NASA OSIRIS REX OLA

    NASA OSIRIS REX OTES
    NASA OSIRIS REX OTES

    NASA OSIRIS-REX OVIRS
    NASA OSIRIS-REX OVIRS

    NASA OSIRIS REX FEROS
    NASA OSIRIS REX FEROS

    These instruments will be dealt with in future posts.

    For more information on OSIRIS-REx visit:
    http://www.nasa.gov/osiris-rex
    and
    http://www.asteroidmission.org

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 7:46 am on June 24, 2016 Permalink | Reply
    Tags: , , NASA Goddard,   

    From Goddard: “X-ray Echoes of a Shredded Star Provide Close-up of ‘Killer’ Black Hole” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    June 22, 2016
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland
    francis.j.reddy@nasa.gov

    Some 3.9 billion years ago in the heart of a distant galaxy, the intense tidal pull of a monster black hole shredded a star that passed too close. When X-rays produced in this event first reached Earth on March 28, 2011, they were detected by NASA’s Swift satellite, which notified astronomers around the world.

    NASA/SWIFT Telescope
    NASA/SWIFT Telescope

    Within days, scientists concluded that the outburst, now known as Swift J1644+57, represented both the tidal disruption of a star and the sudden flare-up of a previously inactive black hole.


    Access mp4 video here .
    NASA Goddard astronomer Erin Kara discusses the discovery of X-ray echoes from Swift J1644+57, a black hole that shattered a passing star. X-rays produced by flares near this million-solar-mass black hole bounced off the nascent accretion disk and revealed its structure. Credits: NASA’s Goddard Space Flight Center

    Now astronomers using archival observations from Swift, the European Space Agency’s (ESA) XMM-Newton observatory and the Japan-led Suzaku satellite have identified the reflections of X-ray flares erupting during the event.

    ESA/XMM Newton
    ESA/XMM Newton

    JAXA/Suzaku satellite
    JAXA/Suzaku satellite

    Led by Erin Kara, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park (UMCP), the team has used these light echoes, or reverberations, to map the flow of gas near a newly awakened black hole for the first time.

    “While we don’t yet understand what causes X-ray flares near the black hole, we know that when one occurs we can detect its echo a couple of minutes later, once the light has reached and illuminated parts of the flow,” Kara explained. “This technique, called X-ray reverberation mapping, has been previously used to explore stable disks around black holes, but this is the first time we’ve applied it to a newly formed disk produced by a tidal disruption.”


    Access mp4 video here .
    Astronomers using data from the European Space Agency’s XMM-Newton satellite have found a long-sought X-ray signal from NGC 4151, a galaxy that contains a supermassive black hole. When the black hole’s X-ray source flares, its accretion disk brightens about half an hour later. The discovery promises a new way to unravel what’s happening in the neighborhood of these powerful objects. Credit: NASA’s Goddard Space Flight Center

    1
    In this artist’s rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole. Credits: NASA/Swift/Aurore Simonnet, Sonoma State University

    Stellar debris falling toward a black hole collects into a rotating structure called an accretion disk. There the gas is compressed and heated to millions of degrees before it eventually spills over the black hole’s event horizon, the point beyond which nothing can escape and astronomers cannot observe. The Swift J1644+57 accretion disk was thicker, more turbulent and more chaotic than stable disks, which have had time to settle down into an orderly routine. The researchers present the findings in a paper published online in the journal Nature on Wed., June 22.

    One surprise from the study is that high-energy X-rays arise from the inner part of the disk. Astronomers had thought most of this emission originated from a narrow jet of particles accelerated to near the speed of light. In blazars, the most luminous galaxy class powered by supermassive black holes, jets produce most of the highest-energy emission.

    “We do see a jet from Swift J1644, but the X-rays are coming from a compact region near the black hole at the base of a steep funnel of inflowing gas we’re looking down into,” said co-author Lixin Dai, a postdoctoral researcher at UMCP. “The gas producing the echoes is itself flowing outward along the surface of the funnel at speeds up to half the speed of light.”

    X-rays originating near the black hole excite iron ions in the whirling gas, causing them to fluoresce with a distinctive high-energy glow called iron K-line emission. As an X-ray flare brightens and fades, the gas follows in turn after a brief delay depending on its distance from the source.

    “Direct light from the flare has different properties than its echo, and we can detect reverberations by monitoring how the brightness changes across different X-ray energies,” said co-author Jon Miller, a professor of astronomy at the University of Michigan in Ann Arbor.

    Swift J1644+57 is one of only three tidal disruptions that have produced high-energy X-rays, and to date it remains the only event caught at the peak of this emission. These star shredding episodes briefly activate black holes astronomers wouldn’t otherwise know about. For every black hole now actively accreting gas and producing light, astronomers think nine others are dormant and dark. These quiescent black holes were active when the universe was younger, and they played an important role in how galaxies evolved. Tidal disruptions therefore offer a glimpse of the silent majority of supersized black holes.

    3
    Images from Swift’s Ultraviolet/Optical (white, purple) and X-Ray telescopes (yellow and red) were combined in this composite of Swift J1644+57, an X-ray outburst astronomers classify as a tidal disruption event. The event is seen only in the X-ray image, which is a 3.4-hour exposure taken on March 28, 2011. The outburst was triggered when a passing star came too close to a supermassive black hole. The star was torn apart, and much of the gas fell toward the black hole. To date, this is the only tidal disruption event emitting high-energy X-rays that astronomers have caught at peak luminosity. Credits: NASA/Swift/Stefan Immler

    “If we only look at active black holes, we might be getting a strongly biased sample,” said team member Chris Reynolds, a professor of astronomy at UMCP. “It could be that these black holes all fit within some narrow range of spins and masses. So it’s important to study the entire population to make sure we’re not biased.”

    The researchers estimate the mass of the Swift J1644+57 black hole at about a million times that of the sun but did not measure its spin. With future improvements in understanding and modeling accretion flows, the team thinks it may be possible to do so.

    ESA’s XMM-Newton satellite was launched in December 1999 from Kourou, French Guiana. NASA funded elements of the XMM-Newton instrument package and provides the NASA Guest Observer Facility at Goddard, which supports use of the observatory by U.S. astronomers. Suzaku operated from July 2005 to August 2015 and was developed at the Japanese Institute of Space and Astronautical Science, which is part of the Japan Aerospace Exploration Agency, in collaboration with NASA and other Japanese and U.S. institutions.

    NASA’s Swift satellite was launched in November 2004 and is managed by Goddard. It is operated in collaboration with Penn State University in University Park, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corp. in Dulles, Virginia, with international collaborators in the U.K., Italy, Germany and Japan.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 10:15 am on June 22, 2016 Permalink | Reply
    Tags: , , , , NASA Goddard, ,   

    From Goddard: “Astronomers Find the First ‘Wind Nebula’ Around a Magnetar” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    June 21, 2016
    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    Astronomers have discovered a vast cloud of high-energy particles called a wind nebula around a rare ultra-magnetic neutron star, or magnetar, for the first time. The find offers a unique window into the properties, environment and outburst history of magnetars, which are the strongest magnets in the universe.

    1
    This X-ray image shows extended emission around a source known as Swift J1834.9-0846, a rare ultra-magnetic neutron star called a magnetar. The glow arises from a cloud of fast-moving particles produced by the neutron star and corralled around it. Color indicates X-ray energies, with 2,000-3,000 electron volts (eV) in red, 3,000-4,500 eV in green, and 5,000 to 10,000 eV in blue. The image combines observations by the European Space Agency’s XMM-Newton spacecraft taken on March 16 and Oct. 16, 2014. Credits: ESA/XMM-Newton/Younes et al. 2016

    ESA/XMM Newton
    ESA/XMM Newton

    A neutron star is the crushed core of a massive star that ran out of fuel, collapsed under its own weight, and exploded as a supernova. Each one compresses the equivalent mass of half a million Earths into a ball just 12 miles (20 kilometers) across, or about the length of New York’s Manhattan Island. Neutron stars are most commonly found as pulsars, which produce radio, visible light, X-rays and gamma rays at various locations in their surrounding magnetic fields. When a pulsar spins these regions in our direction, astronomers detect pulses of emission, hence the name.

    2
    This illustration compares the size of a neutron star to Manhattan Island in New York, which is about 13 miles long. A neutron star is the crushed core left behind when a massive star explodes as a supernova and is the densest object astronomers can directly observe. Credits: NASA’s Goddard Space Flight Center

    Typical pulsar magnetic fields can be 100 billion to 10 trillion times stronger than Earth’s. Magnetar fields reach strengths a thousand times stronger still, and scientists don’t know the details of how they are created. Of about 2,600 neutron stars known, to date only 29 are classified as magnetars.

    The newfound nebula surrounds a magnetar known as Swift J1834.9-0846 — J1834.9 for short — which was discovered by NASA’s Swift satellite on Aug. 7, 2011, during a brief X-ray outburst.

    NASA/SWIFT Telescope
    NASA/SWIFT Telescope

    Astronomers suspect the object is associated with the W41 supernova remnant, located about 13,000 light-years away in the constellation Scutum toward the central part of our galaxy.

    “Right now, we don’t know how J1834.9 developed and continues to maintain a wind nebula, which until now was a structure only seen around young pulsars,” said lead researcher George Younes, a postdoctoral researcher at George Washington University in Washington. “If the process here is similar, then about 10 percent of the magnetar’s rotational energy loss is powering the nebula’s glow, which would be the highest efficiency ever measured in such a system.”

    A month after the Swift discovery, a team led by Younes took another look at J1834.9 using the European Space Agency’s (ESA) XMM-Newton X-ray observatory, which revealed an unusual lopsided glow about 15 light-years across centered on the magnetar. New XMM-Newton observations in March and October 2014, coupled with archival data from XMM-Newton and Swift, confirm this extended glow as the first wind nebula ever identified around a magnetar. A paper describing the analysis will be published by The Astrophysical Journal.

    “For me the most interesting question is, why is this the only magnetar with a nebula? Once we know the answer, we might be able to understand what makes a magnetar and what makes an ordinary pulsar,” said co-author Chryssa Kouveliotou, a professor in the Department of Physics at George Washington University’s Columbian College of Arts and Sciences.

    The most famous wind nebula, powered by a pulsar less than a thousand years old, lies at the heart of the Crab Nebula supernova remnant in the constellation Taurus. Young pulsars like this one rotate rapidly, often dozens of times a second. The pulsar’s fast rotation and strong magnetic field work together to accelerate electrons and other particles to very high energies. This creates an outflow astronomers call a pulsar wind that serves as the source of particles making up in a wind nebula.

    Supernova remnant Crab nebula. NASA/ESA Hubble
    The best-known wind nebula is the Crab Nebula, located about 6,500 light-years away in the constellation Taurus. At the center is a rapidly spinning neutron star that accelerates charged particles like electrons to nearly the speed of light. As they whirl around magnetic field lines, the particles emit a bluish glow. This image is a composite of Hubble observations taken in late 1999 and early 2000. The Crab Nebula spans about 11 light-years. Credits: NASA, ESA, J. Hester and A. Loll (Arizona State University)

    “Making a wind nebula requires large particle fluxes, as well as some way to bottle up the outflow so it doesn’t just stream into space,” said co-author Alice Harding, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We think the expanding shell of the supernova remnant serves as the bottle, confining the outflow for a few thousand years. When the shell has expanded enough, it becomes too weak to hold back the particles, which then leak out and the nebula fades away.” This naturally explains why wind nebulae are not found among older pulsars, even those driving strong outflows.

    A pulsar taps into its rotational energy to produce light and accelerate its pulsar wind. By contrast, a magnetar outburst is powered by energy stored in the super-strong magnetic field. When the field suddenly reconfigures to a lower-energy state, this energy is suddenly released in an outburst of X-rays and gamma rays. So while magnetars may not produce the steady breeze of a typical pulsar wind, during outbursts they are capable of generating brief gales of accelerated particles.

    “The nebula around J1834.9 stores the magnetar’s energetic outflows over its whole active history, starting many thousands of years ago,” said team member Jonathan Granot, an associate professor in the Department of Natural Sciences at the Open University in Ra’anana, Israel. “It represents a unique opportunity to study the magnetar’s historical activity, opening a whole new playground for theorists like me.”

    ESA’s XMM-Newton satellite was launched on Dec. 10, 1999, from Kourou, French Guiana, and continues to make observations. NASA funded elements of the XMM-Newton instrument package and provides the NASA Guest Observer Facility at Goddard, which supports use of the observatory by U.S. astronomers.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard campus

    NASA/Goddard Campus

    NASA image

     
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