‘Killer’ electrons are highly energetic, negatively charged particles found in near-Earth space. They can critically, and even permanently, damage satellites in orbit, including telecommunication satellites, and pose a hazard to astronauts.
Several theories have been formulated in the past to explain the origin of killer electrons, and many uncoordinated observations have already been performed. Recently, scientists got a boost in their understanding of this hazardous phenomenon. This was possible thanks to a unique set of data, collected simultaneously, by a global armada of ground and space observatories during the recovery phase of a large geomagnetic storm.
The results come from complementary studies performed by teams led by Jonathan Rae at the University of Alberta, Canada and Qiugang Zong from the University of Massachusetts, Lowell, USA.
In the aftermath of the storm, the CARISMA (Canadian Array for Realtime Investigations of Magnetic Activity) magnetometer chain observed a type of Ultra Low Frequency (ULF) electromagnetic wave, well-known for creating killer electrons. CARISMA observed the so-called ‘Pc5 waves’ continuously, for many hours, during the recovery phase of a large geomagnetic storm on 25 November 2001. In the meantime, they were also picked up by more than half a dozen scientific satellites located inside Earth’s magnetic environment, or magnetosphere, including NASA’s Polar mission.
Meanwhile, ESA’s four Cluster satellites were located at the boundary of Earth’s magnetosphere, called the magnetopause. They observed undulations, or disturbances of the magnetopause, at the same frequency as that of Pc5 waves observed from inside the magnetosphere.
Taking into account data from all satellites, Earth-based radars and magnetometers, Rae's team were able to reveal the mechanism behind the scenario.
During this event, the velocity of solar wind - a continuous stream of solar particles impacting and shaping Earth’s magnetosphere – was measured at approximately 750 km/s, nearly twice its average speed. The impact of this fast flow of solar particles on Earth’s magnetosphere induced the undulations observed by Cluster.
In turn, these undulations drove compressional waves, which propagated inward from the magnetopause towards Earth. Close to the location of the Polar satellite, these compressional waves coupled with Earth’s magnetic field lines, making the field lines resonate at the frequency of Pc5 waves, which are able to create killer electrons.
Data from Cluster also played a key role in the findings of the study by Zong's team. They focused on the aftermath of another geomagnetic storm, which occurred on 31 October 2003. They not only confirmed that Pc5 waves accelerate electrons, but they have also succeeded in quantifying – for the first time, in situ – the velocity reached by the accelerated electrons.
“Earth’s magnetosphere is a very large, complex and variable system. This makes the understanding of ULF waves, together with the mechanisms for the energy transfer from space to ground, a very difficult matter,” says Philippe Escoubet, ESA's Cluster and Double Star Project Scientist.
“These new results on ULF waves and killer electrons once again highlight the need for simultaneous observations from space and ground. Only with constant monitoring with ground-based instruments can we put data obtained in space into a global context,” he added.
Arnaud Masson | alfa
Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Physics and Astronomy
19.10.2017 | Physics and Astronomy
19.10.2017 | Life Sciences