Study by UCLA researchers and others could explain mysterious plasma waves in space
In the 1960s, NASA launched six satellites to study the Earth's atmosphere, magnetosphere and the space between Earth and the moon. Using observations from those satellites, Christopher Russell, a UCLA graduate student at the time, detected mysterious plasma waves in the Van Allen radiation belts, the donut-shaped rings surrounding the Earth that contain high-energy particles trapped by the planet's magnetic field.
Referred to as equatorial noise or "Russell noise," in tribute to Russell -- who is now a professor of space physics and planetary science at UCLA -- the waves are among the most frequently observed emissions in the near-Earth space. But until recently, scientists could not explain how these waves are excited.
Now, after nearly a half century, the mystery has been solved -- by a team co-led by another UCLA scientist.
Yuri Shprits, a research geophysicist in the UCLA College, and his colleagues discovered the structure of these waves when they are very close to the equator. The scientists observed 13 equally spaced lines measured by two European Space Agency Cluster satellites, and found highly structured wave spectrograms that look like a zebra pedestrian crossing.
"It's truly remarkable how nature managed to draw such clear, very narrow, and periodic lines in space," said Shprits, who led the study with Michael Balikhin of the University of Sheffield.
The finding represents a major advance because the high-energy particles can be harmful for satellites and humans in space. The research is reported in the journal Nature Communications.
The European Cluster spacecraft observed ring distributions of protons in space that provide the energy for the plasma waves. Modelling of waves based on these observations provided additional evidence that waves are excited by so-called proton ring distributions.
Scientists have been especially interested in equatorial noise because it can accelerate particles in the Van Allen belts to high energies and cause the particles to disappear into the atmosphere. This phenomenon may have important implications for space weather and may play an important role in the acceleration and scattering of electrons and ions by these waves that can cause problems ranging from minor anomalies to the complete failure of critical satellites. Better understanding of space radiation will be instrumental in better protecting astronauts and equipment, Shprits said.
Shprits added that similar wave generation mechanisms may also be taking place in the magnetospheres of the outer planets, close to the sun and in distant corners of the universe.
Russell, who also is the principal investigator of NASA's Dawn mission, was pleased with the findings. "It is interesting that with Yuri's work, almost a half century later, scientists are finally making the measurements in space that explain the surprising observations made in 1966 and reported in my 1968 thesis," he said. "The waves were a real a puzzle, and now they make much more sense."
The wave modelling was done by Lunjin Chen, who received his doctorate at UCLA in 2011 and is now an assistant professor at the University of Texas, Dallas.
Shprits was honored by President Barack Obama in 2012 with a Presidential Early Career Award for Scientists and Engineers for his innovative research. The Nature Communications study was funded by the PECASE award (NASA grant NNX10AK99G), and by the National Science Foundation (GEM AGS-1203747) and the University of California Office of the President (12-LR-235337).
Stuart Wolpert | EurekAlert!
Rapid water formation in diffuse interstellar clouds
25.06.2018 | Max-Planck-Institut für Kernphysik
When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
Russian researchers together with their French colleagues discovered that a genuine feature of superconductors -- quantum Abrikosov vortices of supercurrent -- can also exist in an ordinary nonsuperconducting metal put into contact with a superconductor. The observation of these vortices provides direct evidence of induced quantum coherence. The pioneering experimental observation was supported by a first-ever numerical model that describes the induced vortices in finer detail.
These fundamental results, published in the journal Nature Communications, enable a better understanding and description of the processes occurring at the...
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
25.06.2018 | Physics and Astronomy
25.06.2018 | Earth Sciences
25.06.2018 | Power and Electrical Engineering