for National Geographic News
Scientists have discovered the force that creates "killer electrons," particles that pose a significant hazard to spacecraft and astronauts.
The supercharged particles are also a menace to satellites, which are increasingly vital to phones, television, and other communication systems.
Killer electrons are found in the outermost of Earth's doughnut-shaped radiation belts. The belts circle the Earth and are bound by the planet's magnetic fields.
Scientists have long pondered where the killer particles come from and how they accumulate in the radiation belts.
Some theories suggest that they originate in the sun, which produces similar particles, or are the remnants of cosmic rays from outside our solar system.
(See an interactive map of the solar system.)
But a team at New Mexico's Los Alamos National Laboratory may have solved the mystery, and their findings suggest the particles actually form much closer to home.
Using satellite detectors to probe the outer radiation belt, the team found that killer electrons occur extremely unevenly.
Such localized peaks in intensity, the researcher say, could only be caused by electromagnetic waves accelerating electrons to "killer" status within the radiation belt.
"I think we show conclusively they do not come from further out [in space]. They are accelerated in the radiation belt itself," said Reiner Friedel, co-author of a paper published in the July issue of the journal Nature Physics.
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The discovery may aid scientists in ongoing efforts to protect satellites and astronauts from the particles' damaging effects.
Killer electrons travel at near light speed, and each may be charged with a thousand times more energy than the average dental x-ray, scientists say.
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