Hi dear ones,
Take a bunch of fast-moving electrons, place them in orbit and then hit
them with the shock waves from a solar storm. What do you get? Killer electrons.
That’s the shocking recipe revealed by ESA’s Cluster mission.
Killer electrons are highly energetic particles trapped in Earth’s outer
radiation belt, which extends from 12 000 km to 64 000 km above the planet’s surface. During solar storms their number grows at least ten times and they can be dislodged, posing a threat to satellites. As the name suggests, killer electrons are energetic enough to penetrate satellite shielding and cause microscopic lightning strikes. If these electrical discharges take place in vital components, the satellite can be damaged or even rendered inoperable.
Understanding the origin of the killer electrons has been a focus for space
weather researchers. Thanks to previous data collected by Cluster and other space missions, scientists proposed two methods by which electrons can be accelerated to such harmful energy levels. One relies on very low frequency (VLF) waves of 3-30 kHz, the other on ultra low frequency (ULF) waves of 0.001-1 Hz.
This latest work disentangles the problem.
Which waves are responsible? Both of them. “Both VLF and ULF waves accelerate electrons in Earth’s radiation belts, but with different timescales.
The ULF waves are much faster than the VLF, due to their much larger amplitudes.
The data show that a two-step process causes the substantial rise of killer
electrons. The initial acceleration is due to the strong shock-related magnetic field compression. Immediately after the impact of the interplanetary shock, Earth’s magnetic field lines began wobbling at ultra low frequencies.
In turn, these ULF waves were found to effectively accelerate the seed
electrons provided by the first step, to become killer electrons.