Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Killer electrons in space are now less mysterious

27.07.2007
A rare, timely conjunction of ground-based instrumentation and a dozen satellites has helped scientists better understand how electrons in space can turn into ‘killers’. ESA’s Cluster constellation has contributed crucially to the finding.

‘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
Further information:
http://www.esa.int/esaSC/SEMEUMB474F_index_0.html

More articles from Physics and Astronomy:

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>