Friday, July 27, 2007

Sun shakes Earth's Magnetic Field

Killer electrons from Vimeo. Click on arrows for full screen view

ESA's Cluster Mission helps reveal how the Sun shakes the Earth's magnetic field.

Space is a hostile region for astronauts & satellites. One constituent of this hazardous environment around the Earth are very energetic electrons, able to perturb or permanently damage satellites.

Ultra Low Frequency (ULF) waves, which travel along the Earth's magnetic field lines, are a prime candidate for generating these killer electrons, but the source of these waves remains unclear.
[+/-] Click here to expand

A recent study using ground based instrumentation and a dozen satellites at a range of altitudes, provides a means to trace the energy source of these waves from the solar wind into the Earth's magnetosphere down to the ground.

Part of this satellite constellation, the four spacecraft of the ESA Cluster mission, was located at the border of the magnetosphere and played a major role in discriminating between the various theoretical ULF wave generation scenarios.

Quasi-sinusoidal oscillations of the magnetic field lines with periods of a few minutes were recorded continuously for several hours,
as if a celestial musician had plucked the magnetic field lines or strings of the Earth's magnetic guitar

Several ways of exciting these waves have been proposed. Most of them involve the solar wind as the external driver. The solar wind is a continuous stream of solar particles impacting and shaping the Earth's magnetic environment. However, understanding the global nature of these geomagnetic pulsations and the tracing of the energy transfer from the solar wind to the ground is a difficult task.

It requires a fortuitous alignment of several satellites, together with ground–based instruments to observe the oscillations simultaneously.

More from ESA releases
A space armada and ground based instruments to track ULF waves
Image & Simulation Credit: Andy Kale, University of Alberta
'Killer' electrons in orbit explained by Heather Catchpole @ Cosmos Magazine
Killer Electrons In Space Are Now Less Mysterious from Science Daily releases


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