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  • richardmitnick 10:05 am on February 21, 2019 Permalink | Reply
    Tags: , , , , , ESA/NASA SOHO, , ,   

    From European Space Agency via Manu Garcia, a friend from IAC: “The limits of the Earth’s atmosphere” 


    From Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

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    From European Space Agency

    20 February, 2019

    Igor Baliukin
    Space Research Institute
    Russian Academy of Science
    Moscow, Russia
    Email: igor.baliukin@gmail.com

    Jean-Loup Bertaux
    Former principal investigator of SWAN
    Laboratoire Atmospheres Milieux, Observations Spatiales (LATMOS)
    Université de Versailles-Saint-Quentin-en-Yvelines, France
    Email: jean-loup.bertaux@latmos.ipsl.fr

    Bernhard Fleck
    SOHO project scientist
    European Space Agency
    Email: bfleck@esa.nascom.nasa.gov

    Markus Bauer
    ESA Science Program Communication Officer
    Tel: +31 71 565 6799
    Mob: +31 61 594 3 954
    Email: markus.bauer@esa.int

    Earth’s atmosphere reaches the Moon and beyond.
    1
    The extent of land geocorona. Where the atmosphere of the Earth merges with outer space, there is a cloud of hydrogen atoms called geocorona. A recent discovery based on observations of the Solar and Heliospheric Observatory ESA / NASA SOHO shows that geocorona extends far beyond the orbit of the Moon, reaching up to 630 000 km above the surface of the Earth, or 50 times the diameter of our planet. Note: The illustration is not to scale. Credit: ESA.

    The most distant region of our atmosphere extends beyond the lunar orbit, up to twice the distance to our natural satellite.

    Thanks to data collected by the Solar and Heliospheric Observatory (SOHO) of ESA / NASA, a recent discovery shows that the gas layer that surrounds the Earth has a radius of 630,000 km, 50 times the diameter of our planet.

    ESA/NASA SOHO

    “The moon orbits inside the Earth’s atmosphere,” says Igor Baliukin, the Russian Space Research Institute and lead author of the paper presenting the results.

    “We were not aware of it until we recover the observations made over two decades ago by SOHO.”

    In the region where the atmosphere merges into the outer space, there is a cloud of hydrogen atoms called “geocorona”. One of the satellite instruments, SWAN [no image available], used its sensors to track the signing of hydrogen and accurately detect how far the limit of the geocorona arrived.

    These observations could be made only at certain times of the year when the Earth and its geocorona were visible instrument.

    In the planets with their exosferas hydrogen, water vapor often seen near the surface. This is what happens on Earth, Mars and Venus.

    Jean-Loup Bertaux as, former principal investigator and co-author SWAN explains: “This is particularly interesting when we look for planets with possible water deposits beyond our solar system.”

    The first telescope on the Moon, deployed in 1972 by the Apollo astronauts 16 mission captured an image reminiscent of Earth wrapped in geocorona bright ultraviolet light.

    “At that time, the astronauts on the lunar surface did not know that they were actually immersed in the outermost layers of the geocorona” says Jean-Loup.

    The Sun interacts with the hydrogen atoms through a specific wavelength of the ultraviolet spectrum, called Lyman alpha, these atoms can absorb and emit. As this type of light is absorbed by Earth’s atmosphere, it can only be observed from space.

    With its cell uptake of hydrogen, the SWAN instrument could measure light selectively Lyman alpha geocorona and discard the hydrogen atoms located in interplanetary space.

    The new study has revealed that sunlight compresses the hydrogen atoms in the geocorona of the day side of the Earth, while producing a denser region on the night side. Hydrogen daytime region of higher density remains rather low, with only 70 atoms per cubic centimeter to 60,000 kilometers from the earth’s surface, and about 0.2 atoms at the distance of the Moon.

    “On Earth we would call it empty, so this extra source of hydrogen is not enough to provide space exploration,” Igor added.

    The good news is that these particles do not pose a threat to space travelers of future manned missions to orbit the moon.

    “There is also ultraviolet radiation associated -we recalls Jean-Loup geocorona Bertaux- since the hydrogen atoms are dispersed in all directions, but the impact on astronauts in orbit would be minimal mole compared to the main radiation source : the Sun”.

    The bad news is that the Earth’s future geocorona could interfere with astronomical observations near the moon.

    As Jean-Loup warns: “Space telescopes that observe the sky in ultraviolet wavelengths to study the chemical composition of stars and galaxies have to take this into account.”

    The power of files.
    2
    Print Artist Solar and Heliospheric Observatory ESA / NASA SOHO, with the Sun seen by the extreme ultraviolet telescope satellite images on September 14 , 1999. Credit: Spacecraft: ESA / Medialab ATG; Sun: ESA / NASA SOHO, CC BY-SA 3.0 IGO

    Launched in December 1995, the space observatory SOHO has more than two decades studying the sun, from inside its core to the outer corona and solar wind. The satellite orbits in the first Lagrange point (L1), about 1.5 million kilometers from Earth toward the sun.

    LaGrange Points map. NASA

    Its position is perfect to watch the geocorona from outside. The SWAN instrument SOHO captured images of the Earth and its atmosphere on three occasions between 1996 and 1998.

    The team of researchers from Jean-Loup and Igor in Russia decided to recover this data set from the files for analysis. These unique of all the geocorona from SOHO views are now shedding new light on Earth’s atmosphere.

    “It is often possible to take advantage of archived data many years and do new science with them -constata Bernhard Fleck, SOHO Project Scientist of ESA-. This finding underscores the value of some data collected over 20 years and the outstanding performance of SOHO “.

    More information:
    The article ” SWAN / SOHO Lyman-alpha mapping: the Hydrogen geocorona extends well beyond the Moon .” I Baliukin et al, is accepted for publication in Journal of Geophysical Research: Space Physics.

    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 1:11 pm on November 30, 2017 Permalink | Reply
    Tags: AGU - From the Prow, , , , , ESA/NASA SOHO,   

    From AGU: “22 Years of Solar and Heliospheric Observatory” 

    AGU bloc

    American Geophysical Union

    1
    From the Prow

    30 November 2017
    Bernhard Fleck (ESA SOHO Project Scientist, NASA/GSFC)
    Joseph Gurman (NASA SOHO Project Scientist, NASA/GSFC)
    David Sibeck (Past President, AGU Space Physics and Aeronomy Section, NASA/GSFC)

    ESA/NASA SOHO

    1
    The Solar and Heliospheric Observatory (SOHO) studies the internal structure of the Sun, its outer atmosphere and solar winds, and the stream of ionized gas that is constantly blowing outward through the Solar System.

    The 2nd of December 2017 marks the 22nd launch anniversary of the European Space Agency (ESA) – NASA Solar and Heliospheric Observatory (SOHO). SOHO is the longest-lived heliophysics mission still operating and has provided a nearly continuous record of solar and heliospheric phenomena over a full 22-year magnetic cycle (two 11-year sunspot cycles).

    SOHO’s findings have been documented in over 5000 papers in the peer reviewed literature, authored by more than 4,000 scientists worldwide.

    SOHO provided the first ever images of structures and flows below the Sun’s surface and of activity on the far side of the Sun. SOHO discovered sunquakes and eliminated uncertainties in the internal structure of the Sun as a possible explanation for the “neutrino problem” which concerned the large discrepancy between the high flux of solar neutrinos – particles which are now believed to possess mass and travel at almost the speed of light – predicted from the Sun’s luminosity and the much lower flux that is observed.

    The ultraviolet imagers and spectrometers on SOHO have revealed an extremely dynamic solar atmosphere where plasma flows play an important role and discovered dynamic solar phenomena such as coronal waves.

    SOHO measured the acceleration profiles of both the slow and fast solar wind and identified the source regions of the fast solar wind.

    SOHO revolutionized our understanding of solar-terrestrial relations and dramatically boosted space weather forecasting capabilities by providing, in a near-continuous stream, a comprehensive suite of images covering the dynamic atmosphere and extended corona.

    SOHO has measured and characterized over 28,000 coronal mass ejections (CMEs). CMEs are the most energetic eruptions on the Sun and the major driver of space weather. They are responsible for all of the largest solar energetic particle events in the heliosphere and are the primary cause of major geomagnetic storms. SOHO’s visible-light CME measurements are considered a critical part of the US National Space Weather Action Plan.

    For two solar activity cycles SOHO has measured the total solar irradiance (the “solar constant”) as well as variations in the extreme ultraviolet flux, both of which are important to understand the impact of solar variability on Earth’s climate.

    Besides watching the Sun, SOHO has become the most prolific discoverer of comets in astronomical history: as of late 2017, more than 3,400 comets have been found by SOHO, most of them by amateurs accessing SOHO real-time data via the Internet.

    In such complex areas of research as solar physics, progress is not limited to the work of a few people working by themselves. The scientific achievements of the SOHO mission result from a concerted, multi-disciplinary effort by a large, international community of solar scientists, including sound investments in space hardware, coupled with vigorous and well-coordinated scientific operations and interpretation efforts.

    Also, it is important to note that SOHO was not conceived as a “stand-alone” mission. Together with Cluster – a set of four identical spacecraft operated as a single experiment to explore in three dimensions the plasma and small-scale structure in the Earth’s plasma environment – SOHO formed the Solar-Terrestrial Science Programme (STSP), the first cornerstone of the European Space Agency’s long-term program called “Space Science Horizon 2000”, which was implemented in collaboration with NASA.

    4
    ESA Cluster (4 spacecraft) which work with SOHO

    STSP itself was part of an even larger international effort by NASA, ESA, and JAXA: The International Solar-Terrestrial Physics (ISTP) program, which included SOHO, Cluster, Geotail, Wind, and Polar, achieved an unprecedented understanding of the physics of solar-terrestrial relations by coordinated, simultaneous investigations of the Sun-Earth space environment over an extended period of time and, thus, can be considered the predecessor of NASA’s Living With a Star (LWS) program.

    While SOHO’s continued operation into the 2020s depends only on the longevity of its solar arrays, there is as yet no defined mission to succeed it in providing continuous, earth-Sun-line coronagraph observations. Prior to SOHO, our maximum warning time for extreme, earth-directed solar storms was measured in minutes; now it is 1 – 2 days. It would be prudent to preserve that advantage.

    See the full post here .

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    The purpose of the American Geophysical Union is to promote discovery in Earth and space science for the benefit of humanity.

    To achieve this mission, AGU identified the following core values and behaviors.

    Core Principles

    As an organization, AGU holds a set of guiding core values:

    The scientific method
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    When we are at our best as an organization, we embody these values in our behavior as follows:

    We advance Earth and space science by catalyzing and supporting the efforts of individual scientists within and outside the membership.
    As a learned society, we serve the public good by fostering quality in the Earth and space science and by publishing the results of research.
    We welcome all in academic, government, industry and other venues who share our interests in understanding the Earth, planets and their space environment, or who seek to apply this knowledge to solving problems facing society.
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  • richardmitnick 9:42 am on August 2, 2017 Permalink | Reply
    Tags: , , , , , ESA/NASA SOHO,   

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 4:30 pm on May 8, 2017 Permalink | Reply
    Tags: Berkeley, , ESA/NASA SOHO, , , , 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.


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  • richardmitnick 8:02 am on December 4, 2016 Permalink | Reply
    Tags: , , ESA/NASA SOHO,   

    From SPACE.com: “Sun Storm May Have Caused Flare-Up of Rosetta’s Comet” 

    space-dot-com logo

    SPACE.com

    December 2, 2016
    Nola Taylor Redd

    1
    The ESA/NASA Solar and Heliospheric Observatory spacecraft captured this image of a coronal mass ejection erupting on the sun on Sept. 30, 2015.
    Credit: ESA/NASA/SOHO

    ESA/NASA SOHO
    ESA/NASA SOHO

    Material from the sun may have caused Comet 67P/Churyumov-Gerasimenko to flare up nearly 100 times brighter than average in some parts of the visual spectrum, new research reports.

    At about the same time that charged solar particles slammed into Comet 67P, the European Space Agency’s (ESA) Rosetta spacecraft observed that the icy wanderer dramatically brightened. Initially, scientists assumed that unusual effect came from jets of material within the comet. However, newly released observations of 67P suggest that a burst of charged particles from the sun, known as a coronal mass ejection (CME), could have caused the change.

    “The [brightening] was characterized by a substantial increase in the hydrogen, carbon and oxygen emission lines that increased by roughly 100 times their average brightness on the night of Oct. 5 and 6, 2015,” John Noonan told Space.com. Noonan, who just completed his undergraduate degree at the University of Colorado at Boulder, presented the research at the Division for Planetary Sciences meeting in Pasadena, California, in October.

    After reading a report of a CME that hit 67P at the same time, Noonan realized that the increased emissions from water, carbon dioxide and molecular oxygen observed by Rosetta’s R-Alice instrument could all be explained by the collision of the comet with material jettisoned from the sun.

    “This doesn’t yet rule out that an outburst could have happened, but it looks possible that all of the emissions could have been caused by the CME impact,” Noonan said.

    2
    A simulation reveals how the plasma of the solar wind should interact with Comet 67P/C-G. Credit: Modelling and simulation: Technische Universität Braunschweig and Deutsches Zentrum für Luft- und Raumfahrt; Visualisation: Zuse-Institut Berlin

    Colliding particles

    Rosetta entered orbit around Comet 67P in August 2014, making detailed observations until the probe deliberately crashed into the icy body at the end of its mission in September 2016.

    So Rosetta was tagging along when Comet 67P made its closest pass to the sun in August 2015. (Such “perihelion passages” occur once every 6.45 years — the time it takes the icy object to circle the sun.)

    As 67P neared the sun, newly warmed jets began to release gas from the surface, building up the cloud of debris around the nucleus known as the coma. Jets continued to spout throughout Rosetta’s observations as different regions of the comet rotated into sunlight. Such spouts were initially credited with the extreme brightening that took place in October 2015.

    In addition to warming the comet, the sun also interacted with it through its solar wind, the constant rush of charged particles streaming into space in all directions. Occasionally, the sun also blows off the collections of plasma and charged particles known as CMEs. When CMEs collide with Earth, they can interact with the planet’s magnetic field to create dazzling auroral displays; this interaction can also damage power grids and satellites.

    Niklas Edberg, a scientist on the Rosetta Plasma Consortium Ion and Electron Spectrometer instrument on the spacecraft, and his colleagues recently reported that RPC/IES observed a CME impact on Rosetta at the same time as the bizarre brightening. The ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft detected the CME as it left the sun on Sept. 30, 2015.

    According to Edberg, the CME compressed the plasma material around the comet. Because Rosetta was orbiting within the coma, the probe hadn’t sampled any material streaming from the solar wind since the previous April, and wasn’t expected to do so for several more months. When the CME slammed into the comet, however, the coma was compressed and Rosetta briefly tasted part of the solar wind once again.

    “This suggests that the plasma environment had been compressed significantly, such that the solar wind ions could briefly reach the detector, and provides further evidence that these signatures in the cometary plasma environment are indeed caused by a solar wind event, such as a CME,” Edberg and his team wrote in their study, which was published in the journal Monthly Notices of the Royal Astronomical Society in September 2016.

    Forces at play

    For Noonan, the realization that a CME had impacted the comet at the same time of its unusual brightening had an illuminating effect.

    “I read this [Edberg et al.] paper and realized that the substantial increase in electron density could account for the increased emissions from the coma that R-Alice observed, and set about testing what the density of the coma’s water, carbon dioxide and molecular oxygen components would have to be to match what we saw,” Noonan said.

    Charged particles from the CME may have excited cometary material, causing it to release photons, he added. Some of the observed changes could be created only by interacting electrons, causing what Noonan called “unique fingerprints” that let the scientists know electrons were impacting the material. Of special importance was the transition of oxygen line in the spectra, a change that can only be caused by electrons.

    “During the course of the CME, we saw this line increase in strength by roughly hundredfold,” Noonan said.

    The charged particles were unlikely to have come from the solar wind, which Noonan said would be blocked from ever penetrating this deep.

    While CMEs have been observed around other comets, they have only been viewed remotely. From such great distances, only large-scale changes in the comets’ comas and tails could be observed, Edberg said. Over the course of its two-year mission at Comet 67P, Rosetta’s close orbit allowed it to observe other CMEs interacting with the comet, but Noonan said none were as noticeable as the event of Oct. 5-6, 2015.

    “Prior to Rosetta, these electron impact emissions had never been observed around a comet, and it was these emissions that gave away that the CME might be a factor in causing them,” Noonan said.

    He cautioned that it isn’t a given that the influx of charged particles caused the bizarre brightening, which still could be caused by the jets of material.

    “At this point, we are still working to understand exactly what was the cause to see if it was the CME, and outburst, or both, that caused the emission,” Noonan said.

    Given the timing of the impact, however, it is unlikely that the flare-up was the result of gas released by jets alone.

    “There are more forces at play than just a higher density of gas,” Noonan said.

    See the full article here .

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  • richardmitnick 9:48 am on October 31, 2016 Permalink | Reply
    Tags: , , , , ESA/NASA SOHO   

    From Science: “Solar storms can weaken Earth’s magnetic field” 

    ScienceMag
    Science Magazine

    1
    A coronal mass ejection in 2015, seen here by NASA’s Solar Dynamics Observatory, ended up weakening Earth’s magnetic field.

    Oct. 31, 2016
    Katherine Kornei

    The sun’s warm glow can sometimes turn menacing. Solar storms can shoot plasma wrapped in bits of the sun’s magnetic field into space, sweeping past Earth and disabling satellites, causing widespread blackouts, and disrupting GPS-based navigation. Now, a new study suggests that one such “coronal mass ejection” in 2015 temporarily weakened Earth’s protective magnetic field, allowing solar plasma and radiation from the same storm to more easily reach the atmosphere, potentially posing a danger to astronauts. The study also suggests a potential way to predict such storms in the future.

    On 21 June 2015, a NASA spacecraft called the Solar and Heliospheric Observatory recorded a coronal mass ejection blasting off the sun at roughly 1300 kilometers per second.

    ESA/NASA SOHO
    “ESA/NASA SOHO

    When the burst reached Earth roughly 40 hours later, its magnetic field was oriented opposite to Earth’s own magnetic field, which caused the fields to be attracted to each other and to interact strongly. “It is like bringing two magnets close together,” says physicist Sunil Gupta of the Tata Institute of Fundamental Research in Mumbai, India, and lead author of the new study.

    The resulting interaction converted magnetic energy into kinetic energy and sent charged particles such as cosmic rays raining down on Earth’s magnetosphere, the region around Earth where its own magnetic field is stronger than other magnetic fields in space. The National Oceanic and Atmospheric Administration (NOAA) rated the geomagnetic storm 4 out of 5 on its scale of storm severity. Radio blackouts were reported, and the aurora borealis was spotted as far south as Texas.

    Gupta and his team collected data from a telescope in India that measures the number of charged particles called muons that are created as byproducts when cosmic rays hit Earth’s atmosphere. Looking at data from 22 June 2015, they found a statistically significant spike in the number of muons that day. This result was consistent with a weakening of Earth’s magnetic field that allowed cosmic rays to stream more freely through Earth’s magnetnosphere and into the atmosphere without being deflected.

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

    “The weakening of Earth’s magnetic field opens up floodgates for low-energy solar plasma to pour into the atmosphere,” says Gupta, whose team reports its findings this month in Physical Review Letters.

    Overall, the team showed that Earth’s magnetic field is susceptible to temporary damage, rendering our planet’s atmosphere the last line of defense against energetic particles from space. Without Earth’s magnetic field, astronauts above the atmosphere are exposed to particles that can rip through human bodies and damage DNA, potentially causing cancer.

    The new results also suggest a possible method to detect impending geomagnetic storms. A successful early warning system is key to reducing the economic impact of such storms, which has been estimated by the National Academy of Sciences to be several trillion dollars in the most severe cases. Even with only a few hours of advance warning, power grids could redistribute currents to reduce their vulnerability to currents traveling through Earth and airplanes flying polar routes could be rerouted to avoid losing radio contact with controllers, for example.

    Gupta and his colleagues propose using muons as early detectors of geomagnetic storms. The scientists begin by assuming that particles with lower energies take longer to travel through turbulent magnetic fields, much like a lazy moth takes longer to cross a windy valley than a quick bee. They accordingly reasoned that the highly energetic cosmic rays creating muons would reach Earth’s atmosphere ahead of the solar plasma and lower-energy cosmic rays that can be the brunt of a geomagnetic storm. “The muon burst could in principle serve as an early warning system before a storm,” Gupta says. “But a lot of research needs to be done to make it a practical proposition.”

    James Chen, a plasma physicist at the Naval Research Laboratory in Washington, D.C., says that predicting the future might not be so simple. “[The muon burst] is part of an ongoing storm so it may have little forecasting value,” he says.

    The results of Gupta and his team are timely: NOAA issued an alert last week warning of an impending “strong” geomagnetic storm. However, even when spotted by spacecraft, the predicted arrival times of storms are uncertain because they are based on simulations of how coronal mass ejections propagate through space. An Earth-based early alert system, based on particle data, might give less warning but be significantly more accurate.

    Earlier this month, U.S. President Barack Obama signed an executive order mandating that the U.S. government “mitigate the effects of geomagnetic disturbances on the electrical power grid” and “ensure the timely redistribution of space weather alerts.” Our technological society, for all of its advances, is still susceptible to the whims of our closest star.

    See the full article here .

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  • richardmitnick 7:28 am on October 18, 2016 Permalink | Reply
    Tags: ESA/NASA SOHO, , ,   

    From Goddard: “Wayward Field Lines Challenge Solar Radiation Models” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    Oct. 17, 2016
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    In addition to the constant emission of warmth and light, our sun sends out occasional bursts of solar radiation that propel high-energy particles toward Earth. These solar energetic particles, or SEPs, can impact astronauts or satellites. To fully understand these particles, scientists must look to their source: the bursts of solar radiation.

    But scientists aren’t exactly sure which of the two main features of solar eruptions –narrow solar flares or wide coronal mass ejections – causes the SEPs during different bursts. Scientists try to distinguish between the two possibilities by using observations, and computer models based on those observations, to map out where the particles could be found as they spread out and traveled away from the sun. NASA missions STEREO and SOHO collect the data upon which these models are built.

    NASA/STEREO spacecraft
    NASA/STEREO spacecraft

    ESA/NASA SOHO
    ESA/NASA SOHO

    Sometimes, these solar observatories saw SEPs on the opposite side of the sun than where the eruption took place. What kind of explosion on the sun could send the particles so far they ended up behind where they started?


    Access mp4 video here .
    This video compares the two models for particle distribution over the course of just three hours after an SEP event. The white line represents a magnetic field line, the general path that the SEPs follow. The line starts at an SEP event at the sun, and leads the particles in a spiral around the sun. The animation of the updated model, on the right, depicts a static field line, but as the SEPs travel farther in space, turbulent solar material causes wandering field lines. In turn, wandering field lines cause the particles to spread much more efficiently than the traditional model, on the left, predicted. Credits: NASA’s Goddard Space Flight Center/UCLan/Stanford/ULB/Joy Ng, producer

    Now a new model has been developed by an international team of scientists, led by the University of Central Lancashire and funded in part by NASA. The new model shows how particles could travel to the back of the sun no matter what type of event first propelled them. Previous models assumed the particles mainly follow the average of magnetic field lines in space on their way from the sun to Earth, and slowly spread across the average over time. The average field line forms a steady path following a distinct spiral because of the sun’s rotation. But the new model takes into consideration that magnetic fields lines can wander – a result of turbulence in solar material as it travels away from the sun.

    With this added information, models now show SEPs spiraling out much wider and farther than previous models predicted – explaining how SEPs find their way to even the far side of the sun. Understanding the nature of SEP distribution helps scientists as they continue to map out the origins of these high-energy particles. A paper published in Astronomy and Astrophysics on June 6, 2016, summarizes the research, a result of collaboration between the University of Central Lancashire, Université Libre de Bruxelles, University of Waikato and Stanford University.

    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
    NASA/Goddard Campus
    NASA image

     
  • richardmitnick 1:04 pm on May 4, 2015 Permalink | Reply
    Tags: , , ESA/NASA SOHO,   

    From NASA: “Bright Filament Eruption” 

    NASA

    NASA

    May 4, 2015
    Holly Zell

    1

    An elongated solar filament that extended almost half the sun’s visible hemisphere erupted into space on April 28-29, 2015, in a large burst of bright plasma. Filaments are unstable strands of solar material suspended above the sun by magnetic forces. Solar astronomers around the world had their eyes on this unusually large filament and kept track as it erupted. Both of the coronagraph instruments on the joint ESA/NASA Solar and Heliospheric Observatory, or SOHO, show the coronal mass ejection associated with the eruption.

    NASA SOHO
    SOHO

    The top image was taken by SOHO’s LASCO C2 coronagraph and the bottom by LASCO C3.

    LASCO, which stands for Large Angle Spectrometric Coronagraph [ on board SOHO], is able to take images of the solar corona by blocking the light coming directly from the Sun with an occulter disk, creating an artificial eclipse within the instrument itself. C2 images show the inner solar corona up to 8.4 million kilometers (5.25 million miles) away from the Sun. C3 images have a larger field of view: They encompass 32 diameters of the Sun. To put this in perspective, the diameter of the images is 45 million kilometers (about 30 million miles) at the distance of the Sun, or half of the diameter of the orbit of Mercury. The white circle in the center of the round disk represents the size of the sun, which is being blocked by the telescope in order to see the fainter material around it.

    Credit: ESA/NASA/SOHO

    See the full article here.

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
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