Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A perfect sun-storm

28.09.2016

A geomagnetic storm provided unique observations that resolved a long-standing scientific problem. For decades, scientists had asked how particles hitting the Earth's magnetosphere were lost. A likely mechanism involved certain electromagnetic waves scattering particles into the Earth's atmosphere. More recently, another mechanism was proposed that caused particles to be lost in interplanetary space. Yuri Shprits from the GFZ and the University of Potsdam, together with colleagues from several institutions, found that both mechanisms play a role. “This study will help us predict and now-cast the space environment and protect valuable satellites”, says Yuri Shprits.

A geomagnetic storm on January 17, 2013, provided unique observations that finally resolved a long-standing scientific problem. For decades, scientists had asked how particles hitting the Earth's magnetosphere were lost. A likely mechanism involved certain electromagnetic waves scattering particles into the Earth's atmosphere. More recently, another mechanism was proposed that caused particles to be lost in interplanetary space.


Visualization of the Earth‘s magnetic environment (Van Allen belts) and magnetic field lines. For more information see the end of the press release.

Martin Rother, GFZ

Yuri Shprits from the GFZ German Research Centre for Geosciences and the University of Potsdam, together with colleagues from several institutions, recently found that both mechanisms play a role affecting particles at different speeds.

“This study resolves some fundamental scientific questions about our space environment and may also help understand fundamental processes that occur elsewhere in space, on the Sun, in outer planets, distant galaxies, and exoplanets,” says Yuri Shprits. He adds: “This study will also help us predict and now-cast the space environment and protect valuable satellites in space.” The study will appear in Nature Communications on Wednesday, September 28, 2016.

Using measurements from the first US satellite mission, Explorer 1, launched on January 31, 1958, physicist James Van Allen discovered that space was radioactive. Earth is surrounded by two donut-shaped regions of very high particle radiation nested in each other that are referred to as Van Allen Radiation Belts. The high-energy particles that populate the belts create a very harsh environment for satellites and humans in space.

Having very high energy and flying at a speed very close to the speed of light, these particles can induce differential charging on the surface or inside the spacecraft and cause numerous satellite anomalies for telecommunication, navigation, scientific, and Earth-observing satellites. The particles that are most difficult to protect spacecraft from are relativistic and ultra-relativistic electrons.

In recent years, there has been much interest in understanding the Van Allen Radiation Belts. Now more than ever, we rely on technology in space. New technologies of electric orbit raising now require telecommunication satellites to spend a very long time in the Van Allen belts and GPS satellites to operate right in the heart of the belts. Increased miniaturization of space electronics makes satellites more vulnerable to space radiation than ever before.

While it is possible to increase satellite shielding and protect the satellites from relativistic particles (speeds of greater than 0.9 of the speed of light), shielding from ultra-relativistic particles (speeds of greater than 0.99 of the speed of light) is practically impossible. Understanding the dynamics of these particle populations has been a major challenge for scientists since space radiation was discovered over half a century ago. Early observations showed that the belts are very dynamic. Unlike oceans and atmospheres that do not change significantly in short time scales, fluxes of particles in the radiation belts can change by up to a factor of 1000 in a matter of hours or less. The most dramatic are so-called dropouts that often occur during geomagnetic storms that are caused by the solar flares or fast solar wind from the coronal holes.

Since the end of the 1960s and the beginning of the 1970s, much research has been devoted to understanding the loss of electrons from the Van Allen belts. Scientists studied observations from the ground, balloon observations of X-ray bursts and in-situ observations. The loss mechanisms remained elusive and not well understood.

“And yet understanding of loss processes is required to specify the radiation environment and develop models that can now-cast and forecast the radiation environment,” says Yuri Shprits who recently joined the GFZ German Research Centre for Geosciences in a joint appointment with the University of Potsdam.

One of the proposed theories was that particles are scattered into the atmosphere by Electromagnetic Ion Cyclotron Waves (EMIC). These waves are produced by the injection of ions that are heavier than electrons and carry a lot of energy. These waves can potentially scatter electrons into the atmosphere. Up until recently, that remained the most likely candidate for the loss of electrons. In 2006, another mechanism was suggested by Yuri Shprits and colleagues. In this mechanism, particles were lost to the interplanetary space, which resulted in the depletion of particle density and the outward diffusion of electrons. This theory received much attention, and a number of studies provided observational evidence for this loss mechanism. The modeling of the bulk populations of electrons at relativistic energies also seemed to favor this mechanism and did not require additional loss processes by EMIC waves. It remained unclear which mechanism operated or dominated during storms, but did explain the most dramatic dropouts of population in the space environment.

Even increased detailed multipoint satellite observations that have been available since the launch of NASA’s Van Allen Radiation Belt Storms Probe seemed unable to provide definitive answers. Real loss of particles may be difficult to infer as it may be masked by variations associated with the variations in the magnetic field or competing acceleration mechanisms that may operate differently at different energies. Furthermore, both proposed loss mechanisms are intensified during storms, making it very difficult to distinguish one from another. Scientists tried to isolate different processes from each other, but the task seemed to be practically impossible to accomplish.

“The unique combination of events that occurred before and during the January 17, 2013 geomagnetic storms finally allowed us to definitively resolve this long-standing scientific question,” says the lead author of the study, Prof. Yuri Shprits.

The combination of conditions during the January 17, 2013 storms provided a very unique coincidence of different factors that finally allowed scientists from GFZ, University of Potsdam, UCLA, Stanford, Berkeley, Augsburg College, LASP, UNH and Sodankylä Geophysical Observatory.to resolve this long-standing scientific problem. Among the lucky coincidences that helped researchers was: 1) that the belts were populated by a previous storm which allowed detectors to measure detailed distributions of particles in space, energy and direction of propagation during this storm; 2) that the most intense fluxes of relativistic and ultra-relativistic were at different locations in the belts, and therefore particle populations did not affect each other; and 3) ultra-relativistic particles were located deep inside the magnetosphere and were not affected by the loss to the magnetopause.

Detailed measurements on Van Allen Probes showed that EMIC waves were indeed scattering particles into the atmosphere but only affected ultra-relativistic electrons while not affecting relativistic particles that were considered in many previous studies. At ultra-relativistic energies, electrons fly extremely close to the speed of light, and in their reference frame rotate around the field line in the same sense as waves. Being in resonance with electrons, waves can very effectively scatter ultra-relativistic elections into the atmosphere. Distributions in radial distance, energy and direction of velocity all provided definitive evidence that this mechanism of loss is most efficient at ultra-relativistic energies. Detailed modeling including EMIC waves showed remarkably good results, basically identical to the observations, once again confirming the conclusions of the study.

This study resolves some fundamental scientific questions about our space environment and may also help understand fundamental processes that occur elsewhere in space (on the Sun, in outer planets, distant galaxies, and exoplanets). Yuri Shprits adds, “This study will also help us predict and now-cast the space environment and protect valuable satellites in space. It may also help develop methods of cleaning up the radiation belts from harmful radiation and make the environment around the Earth friendlier for satellites.” The study involved 2 GFZ graduate students Irina Zhelavskaya and Nikita Aseev.

Description of the illustration (Image Credit, Martin Rother, GFZ, Section 2.3):

Visualization of the Earth‘s magnetic environment, with the magnetic field as a protective shield, generated by the strong internal magnetic field in the Earth's core. Shown is the magnetosphere close around the Earth, capable of trapping energetic particles in the Earth’s Van Allen radiation belts. The magnetic field lines are depicted by blue ribbons twisted in space, while fluxes of the most energetic electrons are partly exposed by cutting through the surfaces of constant flux intensity.

The visualization used the result of the VERB-4D model performed by Nikita Aseev of GFZ’s section 2.3 and the magnetic model of Tsyganenko 89. All aspects of this illustration including the internal magnetic field, dynamics of the Earth’s magnetic field, and dynamics of the particles trapped by the Earth's magnetic field are studied at GFZ's Section 2.3 (Magnetic Field).
Image Credit, Martin Rother, GFZ, Section 2.3.

Title of the study: Yuri Shprits et al.:“Wave-Induced Loss of Ultra-Relativistic Electrons in the Van Allen Radiation Belts” (Nature Communications, 10.1038/NCOMMS12883)

Weitere Informationen:

Link zu Nature Communications: http://www.nature.com/naturecommunications

Josef Zens | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Further information:
http://www.gfz-potsdam.de/

Further reports about: EMIC GFZ Radiation atmosphere magnetic field satellite satellites space environment speed of light waves

More articles from Earth Sciences:

nachricht More than 100 years of flooding and erosion in 1 event
28.03.2017 | Geological Society of America

nachricht Satellites reveal bird habitat loss in California
28.03.2017 | Duke University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

NASA spacecraft investigate clues in radiation belts

28.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>