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  • richardmitnick 11:10 am on August 12, 2017 Permalink | Reply
    Tags: , , , , , , Solar core spins four times faster than expected, Solar research   

    From physicsworld.com: “Solar core spins four times faster than expected” 

    physicsworld
    physicsworld.com

    Aug 11, 2017
    Keith Cooper

    1
    Sunny science: the Sun still holds some mysteries for researchers. No image credit.

    The Sun’s core rotates four times faster than its outer layers – and the elemental composition of its corona is linked to the 11 year cycle of solar magnetic activity. These two findings have been made by astronomers using a pair of orbiting solar telescopes – NASA’s Solar Dynamics Observatory (SDO) and the joint NASA–ESA Solar and Heliospheric Observatory (SOHO). The researchers believe their conclusions could revolutionize our understanding of the Sun’s structure.

    NASA/SDO

    ESA/NASA SOHO

    Onboard SOHO is an instrument named GOLF (Global Oscillations at Low Frequencies) – designed to search for millimetre-sized gravity, or g-mode, oscillations on the Sun’s surface (the photosphere). Evidence for these g-modes has, however, proven elusive – convection of energy within the Sun disrupts the oscillations, and the Sun’s convective layer exists in its outer third. If solar g-modes exist then they do so deep within the Sun’s radiative core.

    A team led by Eric Fossat of the Université Côte d’Azur in France has therefore taken a different tack. The researchers realized that acoustic pressure, or p-mode, oscillations that penetrate all the way through to the core – which Fossat dubs “solar music” – could be used as a probe for g-mode oscillations. Assessing over 16 years’ worth of observations by GOLF, Fossat’s team has found that p-modes passing through the solar core are modulated by the g-modes that reverberate there, slightly altering the spacing between the p-modes.

    Fossat describes this discovery as “a fantastic result”, in terms of what g-modes can tell us about the solar interior. The properties of the g-mode oscillations depend strongly on the structure and conditions within the Sun’s core, including the ratio of hydrogen to helium, and the period of the g-modes indicate that the Sun’s core rotates approximately once per week. This is around four times faster than the Sun’s outer layers, which rotate once every 25 days at the equator and once every 35 days at the poles.

    Diving into noise

    Not everyone is convinced by the results. Jeff Kuhn of the University of Hawaii describes the findings as “interesting”, but warns that independent verification is required.

    “Over the last 30 years there have been several claims for detecting g-modes, but none have been confirmed,” Kuhn told physicsworld.com. “In their defence, [Fossat’s researchers] have tried several different tests of the GOLF data that give them confidence, but they are diving far into the noise to extract this signal.” He thinks that long-term ground-based measurements of some p-mode frequencies should also contain the signal and confirm Fossat’s findings further.

    If the results presented in Astronomy & Astrophysics can be verified, then Kuhn is excited about what a faster spinning core could mean for the Sun. “It could pose some trouble for our basic understanding of the solar interior,” he says. When stars are born, they are spinning fast but over time their stellar winds rob their outer layers of angular momentum, slowing them down. But Fossat suggests that conceivably their cores could somehow retain their original spin rate.

    Solar links under scrutiny

    Turning attention from the Sun’s core to its outer layers reveals another mystery. The energy generated by nuclear reactions in the Sun’s core ultimately powers the activity in the Sun’s outer layers, including the corona. But the corona is more than a million degrees hotter than the layers of the chromosphere and photosphere below it. The source of this coronal heating is unknown, but a new paper published in Nature Communications has found a link between the elemental composition of the corona, which features a broad spectrum of atomic nuclei including iron and neon, and the Sun’s 11 year cycle of magnetic activity.

    Observations made by SDO between 2010 (when the Sun was near solar minimum) and 2014 (when its activity peaked) revealed that when at minimum, the corona’s composition is dominated by processes of the quiet Sun. However, when at maximum the corona’s composition is instead controlled by some unidentified process that takes place around the active regions of sunspots.

    That the composition of the corona is not linked to a fixed property of the Sun (such as its rotation) but is instead connected to a variable property, could “prompt a new way of thinking about the coronal heating problem,” says David Brooks of George Mason University, USA, who is lead author on the paper. This is because the way in which elements are transported into the corona is thought to be closely related to how the corona is being heated.

    Quest for consensus

    Many explanations for the corona’s high temperature have been proposed, ranging from magnetic reconnection to fountain-like spicules, and magnetic Alfvén waves to nanoflares, but none have yet managed to win over a consensus of solar physicists.

    “If there’s a model that explains everything – the origins of the solar wind, coronal heating and the observed preferential transport – then that would be a very strong candidate,” says Brooks. The discovery that the elemental abundances vary with the magnetic cycle is therefore a new diagnostic against which to test models of coronal heating.

    See the full article here .

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  • richardmitnick 9:42 am on August 2, 2017 Permalink | Reply
    Tags: , , , , , , Solar research   

    From ESA: “Gravity waves detected in Sun’s interior reveal rapidly rotating core” 

    ESA Space For Europe Banner

    European Space Agency

    1 August 2017

    Eric Fossat
    Laboratoire Lagrange
    Université Côte d’Azur
    Observatoire de la Côte d’Azur, France
    Email: Eric.Fossat@oca.eu

    Bernhard Fleck
    ESA SOHO Project Scientist
    Email: bfleck@esa.nascom.nasa.gov

    Markus Bauer
    ESA Science and Robotic Exploration Communication Officer
    Tel: +31 71 565 6799
    Mob: +31 61 594 3 954
    Email: Markus.Bauer@esa.int

    1
    Solar interior. No image credit.

    Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun’s core is rotating four times faster than its surface.

    2
    ESA/NASA SOHO

    Just as seismology reveals Earth’s interior structure by the way in which waves generated by earthquakes travel through it, solar physicists use ‘helioseismology’ to probe the solar interior by studying sound waves reverberating through it. On Earth, it is usually one event that is responsible for generating the seismic waves at a given time, but the Sun is continuously ‘ringing’ owing to the convective motions inside the giant gaseous body.

    Higher frequency waves, known as pressure waves (or p-waves), are easily detected as surface oscillations owing to sound waves rumbling through the upper layers of the Sun. They pass very quickly through deeper layers and are therefore not sensitive to the Sun’s core rotation.

    Conversely, lower frequency gravity waves (g-waves) that represent oscillations of the deep solar interior have no clear signature at the surface, and thus present a challenge to detect directly.

    In contrast to p-waves, for which pressure is the restoring force, buoyancy (gravity) acts as the restoring force of the gravity waves.

    “The solar oscillations studied so far are all sound waves, but there should also be gravity waves in the Sun, with up-and-down, as well as horizontal motions like waves in the sea,” says Eric Fossat, lead author of the paper describing the result, published in Astronomy & Astrophysics.

    “We’ve been searching for these elusive g-waves in our Sun for over 40 years, and although earlier attempts have hinted at detections, none were definitive. Finally, we have discovered how to unambiguously extract their signature.”

    Eric and his colleagues used 16.5 years of data collected by SOHO’s dedicated ‘Global Oscillations at Low Frequencies’ (GOLF) instrument. By applying various analytical and statistical techniques, a regular imprint of the g-modes on the p-modes was revealed.

    In particular, they looked at a p-mode parameter that measures how long it takes for an acoustic wave to travel through the Sun and back to the surface again, which is known to be 4 hours 7 minutes. A series of modulations was detected in this p-mode parameter that could be interpreted as being due to the g-waves shaking the structure of the core.

    The signature of the imprinted g-waves suggests the core is rotating once every week, nearly four times faster than the observed surface and intermediate layers, which vary from 25 days at the equator to 35 days at the poles.

    “G-modes have been detected in other stars, and now thanks to SOHO we have finally found convincing proof of them in our own star,” adds Eric. “It is really special to see into the core of our own Sun to get a first indirect measurement of its rotation speed. But, even though this decades long search is over, a new window of solar physics now begins.”

    The rapid rotation has various implications, for example: is there any evidence for a shear zone between the differently rotating layers? What do the periods of the g-waves tell us about the chemical composition of the core? What implication does this have on stellar evolution and the thermonuclear processes in the core?

    “Although the result raises many new questions, making an unambiguous detection of gravity waves in the solar core was the key aim of GOLF. It is certainly the biggest result of SOHO in the last decade, and one of SOHO’s all-time top discoveries,” says Bernhard Fleck, ESA’s SOHO project scientist.

    ESA’s upcoming solar mission, Solar Orbiter will also ‘look’ into the solar interior but its main focus is to provide detailed insights into the Sun’s polar regions, and solar activity. Meanwhile ESA’s future planet-hunting mission, Plato, will investigate seismic activity in stars in the exoplanet systems it discovers, adding to our knowledge of relevant processes in Sun-like stars.

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    ESA > Our Activities > Space Science >

    Solar interior
    1 August 2017

    Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun’s core is rotating four times faster than its surface.

    Just as seismology reveals Earth’s interior structure by the way in which waves generated by earthquakes travel through it, solar physicists use ‘helioseismology’ to probe the solar interior by studying sound waves reverberating through it. On Earth, it is usually one event that is responsible for generating the seismic waves at a given time, but the Sun is continuously ‘ringing’ owing to the convective motions inside the giant gaseous body.

    Higher frequency waves, known as pressure waves (or p-waves), are easily detected as surface oscillations owing to sound waves rumbling through the upper layers of the Sun. They pass very quickly through deeper layers and are therefore not sensitive to the Sun’s core rotation.

    Conversely, lower frequency gravity waves (g-waves) that represent oscillations of the deep solar interior have no clear signature at the surface, and thus present a challenge to detect directly.

    In contrast to p-waves, for which pressure is the restoring force, buoyancy (gravity) acts as the restoring force of the gravity waves.

    “The solar oscillations studied so far are all sound waves, but there should also be gravity waves in the Sun, with up-and-down, as well as horizontal motions like waves in the sea,” says Eric Fossat, lead author of the paper describing the result, published in Astronomy & Astrophysics.
    SOHO

    “We’ve been searching for these elusive g-waves in our Sun for over 40 years, and although earlier attempts have hinted at detections, none were definitive. Finally, we have discovered how to unambiguously extract their signature.”

    Eric and his colleagues used 16.5 years of data collected by SOHO’s dedicated ‘Global Oscillations at Low Frequencies’ (GOLF) instrument. By applying various analytical and statistical techniques, a regular imprint of the g-modes on the p-modes was revealed.

    In particular, they looked at a p-mode parameter that measures how long it takes for an acoustic wave to travel through the Sun and back to the surface again, which is known to be 4 hours 7 minutes. A series of modulations was detected in this p-mode parameter that could be interpreted as being due to the g-waves shaking the structure of the core.

    The signature of the imprinted g-waves suggests the core is rotating once every week, nearly four times faster than the observed surface and intermediate layers, which vary from 25 days at the equator to 35 days at the poles.

    “G-modes have been detected in other stars, and now thanks to SOHO we have finally found convincing proof of them in our own star,” adds Eric. “It is really special to see into the core of our own Sun to get a first indirect measurement of its rotation speed. But, even though this decades long search is over, a new window of solar physics now begins.”

    The rapid rotation has various implications, for example: is there any evidence for a shear zone between the differently rotating layers? What do the periods of the g-waves tell us about the chemical composition of the core? What implication does this have on stellar evolution and the thermonuclear processes in the core?

    “Although the result raises many new questions, making an unambiguous detection of gravity waves in the solar core was the key aim of GOLF. It is certainly the biggest result of SOHO in the last decade, and one of SOHO’s all-time top discoveries,” says Bernhard Fleck, ESA’s SOHO project scientist.

    ESA’s upcoming solar mission, Solar Orbiter will also ‘look’ into the solar interior but its main focus is to provide detailed insights into the Sun’s polar regions, and solar activity. Meanwhile ESA’s future planet-hunting mission, Plato, will investigate seismic activity in stars in the exoplanet systems it discovers, adding to our knowledge of relevant processes in Sun-like stars.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 9:06 am on June 23, 2017 Permalink | Reply
    Tags: , , Scientists Uncover Origins of the Sun’s Swirling Spicules, Solar research, Swedish 1-meter Solar Telescope in La Palma Spain   

    From Goddard: “Scientists Uncover Origins of the Sun’s Swirling Spicules” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    June 22, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    No image caption or credit.

    At any given moment, as many as 10 million wild jets of solar material burst from the sun’s surface. They erupt as fast as 60 miles per second, and can reach lengths of 6,000 miles before collapsing. These are spicules, and despite their grass-like abundance, scientists didn’t understand how they form. Now, for the first time, a computer simulation — so detailed it took a full year to run — shows how spicules form, helping scientists understand how spicules can break free of the sun’s surface and surge upward so quickly.

    This work relied upon high-cadence observations from NASA’s Interface Region Imaging Spectrograph, or IRIS, and the Swedish 1-meter Solar Telescope in La Palma, in the Canary Islands. Together, the spacecraft and telescope peer into the lower layers of the sun’s atmosphere, known as the interface region, where spicules form. The results of this NASA-funded study were published in Science on June 22, 2017 — a special time of the year for the IRIS mission, which celebrates its fourth anniversary in space on June 26.

    NASA IRIS spacecraft

    2
    Swedish 1-meter Solar Telescope in La Palma, in the Canary Islands, Spain


    Watch the video to learn how scientists used a combination of computer simulations and observations to determine how spicules form.
    Credits: NASA’s Goddard Space Flight Center/Joy Ng, producer

    “Numerical models and observations go hand in hand in our research,” said Bart De Pontieu, an author of the study and IRIS science lead at Lockheed Martin Solar and Astrophysics Laboratory, in Palo Alto, California. “We compare observations and models to figure out how well our models are performing, and to improve the models when we see major discrepancies.”

    Observing spicules has been a thorny problem for scientists who want to understand how solar material and energy move through and away from the sun. Spicules are transient, forming and collapsing over the course of just five to 10 minutes. These tenuous structures are also difficult to study from Earth, where the atmosphere often blurs our telescopes’ vision.

    A team of scientists has been working on this particular model for nearly a decade, trying again and again to create a version that would create spicules. Earlier versions of the model treated the interface region, the lower solar atmosphere, as a hot gas of electrically charged particles — or more technically, a fully ionized plasma. But the scientists knew something was missing because they never saw spicules in the simulations.

    The key, the scientists realized, was neutral particles. They were inspired by Earth’s own ionosphere, a region of the upper atmosphere where interactions between neutral and charged particles are responsible for many dynamic processes.

    The research team knew that in cooler regions of the sun, such as the interface region, not all gas particles are electrically charged. Some particles are neutral, and neutral particles aren’t subject to magnetic fields like charged particles are. Scientists had based previous models on a fully ionized plasma in order to simplify the problem. Indeed, including the necessary neutral particles was very computationally expensive, and the final model took roughly a year to run on the Pleiades supercomputer located at NASA’s Ames Research Center in Silicon Valley, and which supports hundreds of science and engineering projects for NASA missions.

    The model began with a basic understanding of how plasma moves in the sun’s atmosphere. Constant convection, or boiling, of material throughout the sun generates islands of tangled magnetic fields. When boiling carries them up to the surface and farther into the sun’s lower atmosphere, magnetic field lines rapidly snap back into place to resolve the tension, expelling plasma and energy. Out of this violence, a spicule is born. But explaining how these complex magnetic knots rise and snap was the tricky part.

    “Usually magnetic fields are tightly coupled to charged particles,” said Juan Martínez-Sykora, lead author of the study and a solar physicist at Lockheed Martin and the Bay Area Environmental Research Institute in Sonoma, California. “With only charged particles in the model, the magnetic fields were stuck, and couldn’t rise beyond the sun’s surface. When we added neutrals, the magnetic fields could move more freely.”

    Neutral particles provide the buoyancy the gnarled knots of magnetic energy need to rise through the sun’s boiling plasma and reach the chromosphere. There, they snap into spicules, releasing both plasma and energy. Friction between ions and neutral particles heats the plasma even more, both in and around the spicules.

    With the new model, the simulations at last matched observations from IRIS and the Swedish Solar Telescope; spicules occurred naturally and frequently. The 10 years of work that went into developing this numerical model earned scientists Mats Carlsson and Viggo H. Hansteen, both authors of the study from the University of Oslo in Norway, the 2017 Arctowski Medal from the National Academy of Sciences. Martínez-Sykora led the expansion of the model to include the effects of neutral particles.

    The scientists’ updated model revealed something else about how energy moves in the solar atmosphere. It turns out this whip-like process also naturally generates Alfvén waves, a strong kind of magnetic wave scientists suspect is key to heating the sun’s atmosphere and propelling the solar wind, which constantly bathes our solar system and planet with charged particles from the sun.

    “This model answers a lot of questions we’ve had for so many years,” De Pontieu said. “We gradually increased the physical complexity of numerical models based on high-resolution observations, and it is really a success story for the approach we’ve taken with IRIS.”

    The simulations indicate spicules could play a big role in energizing the sun’s atmosphere, by constantly forcing plasma out and generating so many Alfvén waves across the sun’s entire surface.

    “This is a major advance in our understanding of what processes can energize the solar atmosphere, and lays the foundation for investigations with even more detail to determine how big of a role spicules play,” said Adrian Daw, IRIS mission scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “A very nice result on the eve of our launch anniversary.”

    Related:

    IRIS Mission Overview
    New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms

    See the full article here.

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    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.


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  • richardmitnick 12:00 pm on May 13, 2017 Permalink | Reply
    Tags: , , popsci.com, Solar research   

    From popsci.com: “How NASA is planning to touch the sun” 

    popsci-bloc

    Popular Science

    February 14, 2017 [Where has this been?]
    Ian Graber-Stiehl

    A look behind the scenes of NASA’s advanced solar probe

    1
    An explosion on the sun shoots fiery plasma out into space. NASA/Goddard/SDO

    Our sun might not seem as enigmatic as more exotic, distant stars, but it’s still a marvelously mysterious miasma of incandescent plasma. And it’s certainly worthy of our scientific attention: Curiosity aside, a violent solar event could disrupt satellites and cause $2 trillion in damages for the U.S. alone. Yet, despite living in its atmosphere, we don’t understand some of its defining phenomena. For sixty years, we haven’t understood why the surface is a cozy 5,500 Celsius, while the halo called the corona—several million kilometers away from the star’s surface and 12 orders of magnitude less dense—boasts a positively sizzling 1-2 million Celsius.

    To figure out why, NASA needs to fly a little closer to the sun—and touch it.

    We know that magnetic reconnection—when magnetic field lines moving in opposite directions intertwine and snap like rubber bands—propels nuclear weapon-like waves of energy away from surface. Meanwhile, magnetohydrodynamic waves—vibrating guitar string-like waves of magnetic force driven by the flow of plasma—transfer energy from the surface into corona. However, without more data, our understanding of phenomena like coronal heating and solar wind acceleration remain largely theoretical…but not for long.

    Launching in 2018, NASA’s Solar Probe Plus will travel nearly seven years, setting a new record for fastest moving object as it zips 37.6 million kilometers closer to the sun than any spacecraft that has ever studied our host star.

    2
    Artist’s impression of NASA’s Solar Probe Plus spacecraft on approach to the sun. Set to launch in 2018, Solar Probe Plus will orbit the sun 24 times, closing in with the help of seven Venus flybys. The spacecraft will carry 10 science instruments specifically designed to solve two key puzzles of solar physics: why the sun’s outer atmosphere is so much hotter than the sun’s visible surface, and what accelerates the solar wind that affects Earth and our solar system.
    Date 4 December 2008
    Source http://www.jhuapl.edu/newscenter/pressreleases/2014/140318.asp
    Author NASA/Johns Hopkins University Applied Physics Laboratory

    But what manner of sensory equipment does one bring to Dante’s Inferno?

    3
    From top left: the FIELDS experiment, ISIS, WISPR, SWEAP NASA/Johns Hopkins University Applied Physics Laboratory

    Spacecraft systems engineer Mary Kae Lockwood tells PopSci that the craft will rely on four main instruments. The Solar Wind Electrons Alphas and Protons systems, or SWEAP, will monitor charges created by colliding electrons, protons and helium ions to analyze solar wind—ninety times closer to the sun than previous attempts. Similarly, the ISIS (Integrated Science Investigation of the Sun) employs a state-of-the-art detection system to analyze energetic particles (think: cancer-causing, satellite-disabling particles).

    The FIELDS sensor, meanwhile, will analyze electric and magnetic fields, radio emissions, and shock waves—while gathering information on the high-speed dust particles sanding away at the craft using a technique discovered by accident. Lastly, the Wide-field Imager for Solar Probe, or WISPR telescope, will make 3D, cat-scan-like images of solar wind and the sun’s atmosphere.

    There’s just one problem. Between intense heat, solar radiation, high-energy particles, the fallout of solar storms, dust, and limited communication opportunities at closest approach, all that sensitive equipment is going to an environment that almost makes Juno’s new home look sympathetic by comparison.

    “One of the things we had to watch out for in the design,” according to Lockwood, was the electrical “charging” of the spacecraft by the solar wind. The probe has to be conductive “so that the instruments that are actually measuring the solar wind don’t have interference.”

    4
    The probe’s planned trajectory. NASA/Johns Hopkins University Applied Physics Laboratory

    To get close enough to worry about that, though, the probe’s has to “lose some energy” says Lockwood, performing several Venus flybys to shrink its orbit “[allowing] us to get . . . closer and closer to the sun.”

    However, that comes with “interesting design challenges, because you’re not only going into the sun” as heatshield mechanical engineer Beth Congdon tells PopSci. “You get hot on approach, and then come out and get cold,” over and over for 7 flybys and 24 orbits. “You actually need to have it cyclically survive hot and cold temperatures.” And high energy particles. And hypervelocity dust. For that, you need a heat shield “different from any other heat shield that has ever existed.”

    5
    NASA/Johns Hopkins University Applied Physics Laboratory

    The incandescent elephant in the room

    “A lot of heat shields you typically think about, like the shuttle . . . They have a few minutes maximum of that kind of heat.” But at the probe’s closest approach of 5.9 million kilometers, Congdon says, temperatures will reach up to 1,377 Celsius for a full day.

    But carbon can come to the rescue. “On Earth, carbon likes to oxidise and make barbeque,” chimes Congdon, “[but] in the vacuum of space, it’s a great material for high temperature applications. The probe’s shield is made of carbon foam, sandwiched between layers of carbon composite, with a reflective ceramic coating.

    What’s more, she says, most shields have the luxury of being attached to a vibration-dampening platform. This shield, on the other hand, had to be integrated in such a way that it could mitigate vibration without one “so that we could keep the whole system as low mass as possible.” The slim, trim, and ultralight build, however, makes it challenging to keep all the sensitive equipment hidden safely behind it.

    To that end, the craft is outfitted with solar limb sensors. These sensors would be the first thing to get illuminated if the spacecraft started drifting off-kilter, and would inform the autonomous guidance and control system that keeps all the instruments behind the thermal protection system, and which is even outfitted with a backup processor in case of any malfunctions.

    Meanwhile, the solar array, facing solar intensity 475 times greater than here on Earth—in an environment where “one degree of change, at closest approach, equals a 30 percent change in power”—will automatically retract behind the heat shield whenever it swings toward the sun. From there, it’ll be kept at a cool 160 Celsius by a network of water-filled titanium channels.

    So while the heatshield weathers a minefield of million-mile-per-hour winds and countless coronal mass ejections, the communication system scarcely able to relay information for 11 straight days, the array will be kept comfortable—all while powering an autonomous 1,345 lb scientist on the doorstep of our little cosmic neighborhood’s big, confounding catalyst.

    “Going to a place changes everything we think about a place. Just look at New Horizons and how it’s changed our thoughts, beliefs, and understanding of Pluto. We’re really excited to go and totally change our view of the sun,” says Congdon. Understanding the sun’s defining phenomena is a tantalizing goal. But first we have to contend with 143.3 million kilometers of space—and one of NASA’s most technically challenging builds, over half a century in the making.

    See the full article here .

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  • richardmitnick 1:03 pm on May 9, 2017 Permalink | Reply
    Tags: , , , , , RAISE (Rapid Acquisition Imaging Spectrograph Experiment), Solar research   

    From COSMOS: “A simple rocket for staring at the sun” 

    Cosmos Magazine bloc

    COSMOS

    09 May 2017
    Jana Howden

    1
    The RAISE rocket being prepared for take-off. Amir Caspi, Southwest Research Institute

    Capable of snapping 1,500 images in just five minutes, NASA’s newly launched rocket is raising the bar on studies of the sun. RAISE (Rapid Acquisition Imaging Spectrograph Experiment) is a type of sounding rocket, a relatively simple and cost-effective rocket that goes up 300 kilometres and spends 15–20 minutes making observations from above the atmosphere before returning to the ground.

    Although NASA runs several missions geared towards continuous study of the sun, this new sounding rocket, RAISE will allow researchers to study the fast processes and split-second changes occurring near the sun’s active regions.

    These active regions are areas of complex and intense magnetic activity that can cause solar flares, which spew energy and solar material into space.

    “With RAISE, we’ll read out an image every two-tenths of a second, so we can study very fast processes and changes on the sun,” explains Don Hassler, principal investigator for the RAISE mission.

    The data collected by RAISE can be used to create what’s called a spectrogram – a visual representation of the light emitted by the sun at different wavelengths. Looking at the intensity of light at these different wavelengths allows scientists to study the ways in which energy and solar material moves around the sun, and how this can evolve into solar eruptions.

    RAISE was launched on 5 May from a missile range in the US state of New Mexico, soaring to an altitude of around 296 kilometres before parachuting gently down to Earth, where the machine is to be recovered and reused.

    Read more at NASA.

    Related Links

    More about NASA’s sounding rocket program

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  • richardmitnick 4:30 pm on May 8, 2017 Permalink | Reply
    Tags: Berkeley, , , , , Solar research, Space Sciences Laboratory at University of California   

    From Goddard: “Space Weather Model Simulates Solar Storms From Nowhere” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 8, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Our ever-changing sun continuously shoots solar material into space. The grandest such events are massive clouds that erupt from the sun, called coronal mass ejections, or CMEs. These solar storms often come first with some kind of warning — the bright flash of a flare, a burst of heat or a flurry of solar energetic particles. But another kind of storm has puzzled scientists for its lack of typical warning signs: They seem to come from nowhere, and scientists call them stealth CMEs.

    Now, an international team of scientists, led by the Space Sciences Laboratory at University of California, Berkeley, and funded in part by NASA, has developed a model that simulates the evolution of these stealthy solar storms.


    SSL UC Berkeley campus


    Space Science Labs UC Berkeley

    The scientists relied upon NASA missions STEREO and SOHO for this work, fine-tuning their model until the simulations matched the space-based observations.

    NASA/STEREO spacecraft


    ESA/NASA SOHO

    Their work shows how a slow, quiet process can unexpectedly create a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space — all without any advance warning.

    1
    Watch the evolution of a stealth CME in this simulation. Differential rotation creates a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space. The image of the sun is from NASA’s STEREO. Colored lines depict magnetic field lines, and the different colors indicate in which layers of the sun’s atmosphere they originate. The white lines become stressed and form a coil, eventually erupting from the sun. Credits: NASA’s Goddard Space Flight Center/ARMS/Joy Ng, producer

    Compared to typical CMEs, which erupt from the sun as fast as 1800 miles per second, stealth CMEs move at a rambling gait — between 250 to 435 miles per second. That’s roughly the speed of the more common solar wind, the constant stream of charged particles that flows from the sun. At that speed, stealth CMEs aren’t typically powerful enough to drive major space weather events, but because of their internal magnetic structure they can still cause minor to moderate disturbances to Earth’s magnetic field.

    To uncover the origins of stealth CMEs, the scientists developed a model of the sun’s magnetic fields, simulating their strength and movement in the sun’s atmosphere. Central to the model was the sun’s differential rotation, meaning different points on the sun rotate at different speeds. Unlike Earth, which rotates as a solid body, the sun rotates faster at the equator than it does at its poles.

    The model showed differential rotation causes the sun’s magnetic fields to stretch and spread at different rates. The scientists demonstrated this constant process generates enough energy to form stealth CMEs over the course of roughly two weeks. The sun’s rotation increasingly stresses magnetic field lines over time, eventually warping them into a strained coil of energy. When enough tension builds, the coil expands and pinches off into a massive bubble of twisted magnetic fields — and without warning — the stealth CME quietly leaves the sun.

    Such computer models can help researchers better understand how the sun affects near-Earth space, and potentially improve our ability to predict space weather, as is done for the nation by the U.S. National Oceanic and Atmospheric Administration. A paper published in the Journal of Geophysical Research on Nov. 5, 2016, summarizes this work.

    Related

    New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms
    NASA Scientists Demonstrate Technique to Improve Particle Warnings that Protect Astronauts

    See the full article here.

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    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

     
  • richardmitnick 11:25 am on May 8, 2017 Permalink | Reply
    Tags: , , Solar research,   

    From AAS NOVA: ” Escape for the Slow Solar Wind” 

    AASNOVA

    American Astronomical Society

    8 May 2017
    Susanna Kohler

    1
    This Solar Dynamics Observatory extreme ultraviolet image of the Sun reveals a coronal hole — a region of open magnetic field — surrounded by regions of closed magnetic field. A new study examines how plasma might escape from regions of closed magnetic field on the Sun. [SDO; adapted from Higginson et al. 2017]

    NASA/SDO

    Plasma from the Sun known as the slow solar wind has been observed far away from where scientists thought it was produced. Now new simulations may have resolved the puzzle of where the slow solar wind comes from and how it escapes the Sun to travel through our solar system.

    An Origin Puzzle

    The Sun’s atmosphere, known as the corona, is divided into two types of regions based on the behavior of magnetic field lines. In closed-field regions, the magnetic field is firmly anchored in the photosphere at both ends of field lines, so traveling plasma is confined to coronal loops and must return to the Sun’s surface. In open-field regions, only one end of each magnetic field line is anchored in the photosphere, so plasma is able to stream from the Sun’s surface out into the solar system.

    This second type of region — known as a coronal hole — is thought to be the origin of fast-moving plasma measured in our solar system and known as the fast solar wind. But we also observe a slow solar wind: plasma that moves at speeds of less than 500 km/s.

    The slow solar wind presents a conundrum. Its observational properties strongly suggest it originates in the hot, closed corona rather than the cooler, open regions. But if the slow solar wind plasma originates in closed-field regions of the Sun’s atmosphere, then how does it escape from the Sun?

    Slow Wind from Closed Fields

    A team of scientists led by Aleida Higginson (University of Michigan) has now used high-resolution, three-dimensional magnetohydrodynamic simulations to show how the slow solar wind can be generated from plasma that starts out in closed-field parts of the Sun.

    Motions on the Sun’s surface near the boundary between open and closed-field regions — the boundary that marks the edges of coronal holes and extends outward as the heliospheric current sheet — are caused by supergranule-like convective flows. These motions drive magnetic reconnection that funnel plasma from the closed-field region onto enormous arcs that extend far away from the heliospheric current sheet, spanning tens of degrees in latitude and longitude.

    The simulations by Higginson and collaborators demonstrate that closed-field plasma from coronal-hole boundaries can be successfully channeled into the solar system. Due to the geometry and dynamics of the coronal holes, the plasma can travel far from the heliospheric current sheet, resulting in a slow solar wind of closed-field plasma consistent with our observations. These simulations therefore suggest a process that resolves the long-standing puzzle of the slow solar wind.

    Citation

    A. K. Higginson et al 2017 ApJL 840 L10. doi:10.3847/2041-8213/aa6d72

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    See the full article for further research with links.

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  • richardmitnick 8:06 am on May 5, 2017 Permalink | Reply
    Tags: , , , Solar research   

    From Eos: “Integrating Research of the Sun-Earth System” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    2 May 2017
    Vania K. Jordanova
    Joseph E. Borovsky
    Valentin T. Jordanov

    1
    A rendering of the sunset from space. Attendees at a recent symposium convened to chart new courses in research about the reaction of the Earth system to the Sun and the solar wind. Credit: iStock.com/RomoloTavani

    Understanding the complex interactions between the magnetic fields of the Sun and Earth remains an important challenge to space physics research. Processes that occur near the Sun at tens of thousands of kilometers from the Earth can generate geomagnetic storms that affect the entire magnetosphere, down to the upper atmosphere.

    Solar eruption 2012 by NASA’s Solar Dynamic Observatory SDO

    NASA/SDO

    These storms also threaten the ever more sophisticated technologies that we place into the space environment to sustain us, for example, GPS, the satellites we rely on to monitor our weather, and relays that guide our radio transmissions. Increasingly, we need to develop space weather models that can provide timely and accurate predictions so that we can safeguard our society and the infrastructure we depend on.

    Against this backdrop, the third International Symposium on Recent Observations and Simulations of the Sun-Earth System (ISROSES-III) convened in Bulgaria last year to discuss recent advances and chart future developments in space weather research. ISROSES-III built upon the legacy of other similar conferences held in Bulgaria in 2002, 2006, and 2011.

    The main purpose of ISROSES-III was to foster interdisciplinary research and collaboration by enhancing communications between the space and Earth sciences communities worldwide. About 100 participants from around the world convened at the symposium to cover a broad range of topics.

    These topics included the fundamental physics of how waves and shocks in magnetic fields create dangerous radiation by accelerating particles throughout space. One study at the meeting examined the origin of these particles as measured from geosynchronous orbit.

    Another study analyzed the types of magnetic disturbances that lead to geomagnetic storms. Others focused on the structure of Earth’s magnetospheric current systems, improving our understanding of them and how they map to the ionosphere. Yet another detailed an improved representation of magnetospheric electric potential to create more accurate simulations.

    The main emphasis of the discussions was on integrating observations, theory, and numerical modeling across different temporal and spatial scales of the coupled Sun-Earth system.

    The community also highlighted common misconceptions as well as the need to develop contemporary and innovative technologies in space exploration (Figure 1). In the research community, it is easier to denounce new concepts than express doubt in old, deeply held misconceptions. In contrast, in the market economy, old concepts or misconceptions are constantly abandoned in search for something new. Symposium attendees discussed how the market economy has created new technologies that they should explore and that the research community needs to adopt the flexible mindset of corporations.

    1
    Fig. 1. Radiation measurement instrumentation versus consumer technology. (left) In the research community it is easier to denounce new concepts than express doubt in believed old misconceptions. (right) In the market economy, old concepts or misconceptions are constantly abandoned in search for something new. Attendees at a recent symposium on the Sun-Earth system stressed that new ideas brought into focus by the market economy shouldn’t be dismissed and that the research community should adopt the flexible mindset of corporations. Credit: Valentin T. Jordanov

    A special issue of the Journal of Atmospheric and Solar-Terrestrial Physics is currently being organized to publish papers related to topics discussed at ISROSES-III. Further information about the symposium is available on its official website [link is above].

    The main sponsors of the symposium were the Los Alamos National Laboratory Center for Space and Earth Science, the National Science Foundation, and the Scientific Committee on Solar-Terrestrial Physics’s Variability of the Sun and Its Terrestrial Impact (VarSITI) program. ISROSES-III also received collaboration and support locally from the University of Sofia, Bulgaria.

    —Vania K. Jordanova (email: vania@lanl.gov), Los Alamos National Laboratory, Los Alamos, N.M.; Joseph E. Borovsky, Space Science Institute, Boulder, Colo.; and Valentin T. Jordanov, Yantel LLC, Santa Fe, N.M.
    Citation: Jordanova, V. K., J. E. Borovsky, and V. T. Jordanov (2017), Integrating research of the Sun-Earth system, Eos, 98, https://doi.org/10.1029/2017EO072499. Published on 02 May 2017.

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 12:43 pm on May 3, 2017 Permalink | Reply
    Tags: , Solar research, SPACE SCIENCE LAB,   

    From SSL at UC Berkeley: “Solar Array Cooling System Coming Together on Solar Probe Plus” 

    UC Berkeley

    UC Berkeley

    Space Science Labs UC Berkeley

    Space Science Lab

    2
    The Solar Array Cooling System on Solar Probe Plus has one critical job – to protect the NASA spacecraft’s solar arrays from incineration as it moves through the blazing atmosphere of the sun.

    Several key elements of that system are now on board the spacecraft, installed last week during ongoing integration and test operations at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. On April 5, engineers carefully attached the deck that holds the solar array cooling system components, solar array cooling system radiators and the truss structure assembly, or TSA. The TSA will support the spacecraft’s signature 8-foot-wide, 4.5-inch-thick carbon-carbon foam heat shield, as well components from the FIELDS experiment and Solar Wind Electrons, Alphas and Protons (SWEAP) suite that will make direct measurements of the charged particles and electrical fields in the solar environment.

    Solar Probe Plus is on track for launch during a 20-day window that opens July 31, 2018. Integration and testing will continue at APL through November; after that, the spacecraft will be moved to NASA Goddard Space Flight Center in Greenbelt, Maryland, for four months of final space-environmental testing, it is then shipped to Kennedy Space Center/Cape Canaveral Air Force Station, Florida, in March 2018 for final launch preparations. APL designed, is building, and will operate Solar Probe Plus for NASA.

    3
    Mission integration and test team members secure the deck holding the structure assembly and several other critical thermal-protection components atop NASA’s Solar Probe Plus spacecraft body on April 5, 2017, in the cleanroom at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. NASA/Johns Hopkins University Applied Physics Laboratory

    See the full article here .

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    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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  • richardmitnick 9:51 am on April 27, 2017 Permalink | Reply
    Tags: Joint Japan Aerospace Exploration Agency NASA Hinode satellite, , Scientists Propose Mechanism to Describe Solar Eruptions of All Sizes, , , Solar research   

    From Goddard: “Scientists Propose Mechanism to Describe Solar Eruptions of All Sizes” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 26, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    A long filament erupted on the sun on Aug. 31, 2012, shown here in imagery captured by NASA’s Solar Dynamics Observatory. Credit: NASA’s Goddard Space Flight Center/SDO
    From long, tapered jets to massive explosions of solar material and energy, eruptions on the sun come in many shapes and sizes. Since they erupt at such vastly different scales, jets and the massive clouds — called coronal mass ejections, or CMEs — were previously thought to be driven by different processes.

    Scientists from Durham University in the United Kingdom and NASA now propose that a universal mechanism can explain the whole spectrum of solar eruptions. They used 3-D computer simulations to demonstrate that a variety of eruptions can theoretically be thought of as the same kind of event, only in different sizes and manifested in different ways. Their work is summarized in a paper published in Nature on April 26, 2017.


    Follow the evolution of a jet eruption in this video, which uses a 3-D computer simulation of the breakout model to demonstrate how a filament forms, gains energy and erupts from the sun.
    Credits: NASA’s Goddard Space Flight Center/ARMS/Genna Duberstein, producer

    The study was motivated by high-resolution observations of filaments from NASA’s Solar Dynamics Observatory, or SDO, and the joint Japan Aerospace Exploration Agency/NASA Hinode satellite.

    NASA/SDO

    JAXA/HINODE spacecraft

    Filaments are dark, serpentine structures that are suspended above the sun’s surface and consist of dense, cold solar material. The onset of CME eruptions had long been known to be associated with filaments, but improved observations have recently shown that jets have similar filament-like structures before eruption too. So the scientists set out to see if they could get their computer simulations to link filaments to jet eruptions as well.

    “In CMEs, filaments are large, and when they become unstable, they erupt,” said Peter Wyper, a solar physicist at Durham University and the lead author of the study. “Recent observations have shown the same thing may be happening in smaller events such as coronal jets. Our theoretical model shows the jet can essentially be described as a mini-CME.”

    Solar scientists can use computer models like this to help round out their understanding of the observations they see through space telescopes. The models can be used to test different theories, essentially creating simulated experiments that cannot, of course, be performed on an actual star in real life.

    The scientists call their proposed mechanism for how these filaments lead to eruptions the breakout model, for the way the stressed filament pushes relentlessly at — and ultimately breaks through — its magnetic restraints into space. They previously used this model to describe CMEs; in this study, the scientists adapted the model to smaller events and were able to reproduce jets in the computer simulations that match the SDO and Hinode observations. Such simulations provide additional confirmation to support the observations that first suggested coronal jets and CMEs are caused in the same way.

    “The breakout model unifies our picture of what’s going on at the sun,” said Richard DeVore, a co-author of the study and solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Within a unified context, we can advance understanding of how these eruptions are started, how to predict them and how to better understand their consequences.”

    The key for understanding a solar eruption, according to Wyper, is recognizing how the filament system loses equilibrium, which triggers eruption. In the breakout model, the culprit is magnetic reconnection — a process in which magnetic field lines come together and explosively realign into a new configuration.

    NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

    In stable conditions, loops of magnetic field lines hold the filament down and suppress eruption. But the filament naturally wants to expand outward, which stresses its magnetic surroundings over time and eventually initiates magnetic reconnection. The process explosively releases the energy stored in the filament, which breaks out from the sun’s surface and is ejected into space.

    Exactly which kind of eruption occurs depends on the initial strength and configuration of the magnetic field lines containing the filament. In a CME, field lines form closed loops completely surrounding the filament, so a bubble-shaped cloud ultimately bursts from the sun. In jets, nearby fields lines stream freely from the surface into interplanetary space, so solar material from the filament flows out along those reconnected lines away from the sun.

    “Now we have the possibility to explain a continuum of eruptions through the same process,” Wyper said. “With this mechanism, we can understand the similarities between small jets and massive CMEs, and infer eruptions anywhere in between.”

    Confirming this theoretical mechanism will require high-resolution observations of the magnetic field and plasma flows in the solar atmosphere, especially around the sun’s poles where many jets originate — and that’s data that currently are not available. For now, scientists look to upcoming missions such as NASA’s Solar Probe Plus and the joint ESA (European Space Agency)/NASA Solar Orbiter, which will acquire novel measurements of the sun’s atmosphere and magnetic fields emanating from solar eruptions.

    NASA/SPP Solar Probe Plus

    NASA/ESA Solar Orbiter

    See the full article here.

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    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

     
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