Computer animation showing the formation of the third Van Allen radiation belt. Green bar indicates time/day from 9/2/12 to 9/8/12 (UCLA)
New research provides insight into the mysterious Van Allen radiation belts.
There are normally two of these giant bands of high-energy radiation encircling the Earth. However, researchers discovered a third and previously unknown radiation ring that only lasted for about a month back in September 2012.
Writing in a recent edition of Nature Physics, scientists from UCLA College of Letters and Science found the third ring was composed of extremely energetic particles, known as ultra-relativistic electrons, which can move at speeds close to the speed of light.
“The Van Allen Probes observations challenged our current views on the physics of the radiation belts,” said study co-author Yuri Shprits, a space scientist at UCLA. “In the past, we made estimates and thought they looked reasonable. Now we know we need to understand each storm in much more detail, creating global models that can reconstruct what’s happening at every level.”
Armed with data from the Van Allen Probes, two robotic spacecraft that are on two-year mission to study radiation belts, the researchers were able to create new computer models which help explain the extraordinary behavior of that transient third ring.
“The ultra-relativistic electrons of the third ring have so much energy that they are driven by very different physical processes,” said Shprits. “Incorporating that information not only explains the unusual observation of the long-lived narrow middle ring, it opens up a new area of research for the ultra-relativistic particles.”
Artist rendering of the twin Van Allen Probes in Earth orbit (NASA)
The Van Allen belts were the first major discovery of the Space Age when they were first observed by NASA’s Explorer One spacecraft in 1958.
Scientists were able to determine that the belts, which receive their high-energy particles from solar wind and from cosmic rays, expand and contract, as well as change shape, as solar disturbances make their way toward Earth.
These bands of highly-charged energy are kept in place some 1,600 to 60,000 kilometers above the Earth’s surface by our planet’s magnetic fields.
The researchers said better understanding of the radiation belts surrounding Earth might someday help scientists better predict space weather that impacts our planet. Flare ups in space weather can cause problems with orbiting satellites, which in turn could impact communications and GPS systems.
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