NASA spacecraft probe mysteries of Earth's radiation belts

DURHAM, N.H., Dec. 4 (UPI) -- Earth's radiation belts act like a giant particle accelerator, pushing high-energy particles in the belts to nearly the speed of light, NASA scientists say.

That's the latest finding of the Van Allen Probes mission launched a year ago to unravel longstanding mysteries of high-energy radiation belts that encircle the planet and pose hazards to orbiting satellites and astronauts, NASA reported Wednesday.

Data from an onboard instrument developed by the University of New Hampshire reveal Earth's vast magnetic field, or magnetosphere, which contains the Van Allen belts, can rev up drifting electrons to ever-higher speeds as they circle the planet from west to east. The acceleration occurs in conjunction with ultra-low frequency electromagnetic waves operating on a planetary scale, university scientists said.

Earlier measurements by the Energetic Particle, Composition, and Thermal Plasma instrument suite first detected such particle acceleration, but on a microscopic rather than planetary scale, a university release said Wednesday.

"Now we're seeing this large-scale, global motion involving ultra low-frequency waves pulsing through Earth's magnetosphere and operating across vast distances up to hundreds of thousands of kilometers," said Harlan Spence, director of the UNH Institute for the Study of Earth, Oceans, and Space and principal scientist for the ECT instrument.

Understanding the particle acceleration will help create better predictions of space weather conditions, and provide better protection for orbiting satellites, the researchers said.