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Study finds surprising variability in shape of Van Allen Belts

1. The traditional idea of the radiation belts includes a larger, more dynamic outer belt and a smaller, more stable inner belt with an empty slot region separating the two. However, a new study based on data from NASA’s Van Allen Probes shows that all three regions—the inner belt, slot region, and outer belt—can appear differently depending on the energy of electrons considered and general conditions in the magnetosphere. 2. At the highest electron energies measured—above 1 MeV—researchers saw electrons in the outer belt only. 3. The radiation belts look much different at the lowest electron energy levels measured, about 0.1 MeV. Here, the inner belt is much larger than in the traditional picture, expanding into the region that has long been considered part of the empty slot region. The outer belt is diminished and doesn’t expand as far in these lower electron energies. 4. During geomagnetic storms, the empty region between the two belts can fill in completely with lower-energy electrons. Traditionally, scientists thought this slot region filled in only during the most extreme geomagnetic storms happening about once every ten years. However, new data shows it’s not uncommon for lower-energy electrons—up to 0.8 MeV—to fill this space during almost all geomagnetic storms. Credit: NASA Goddard/Duberstein
1. The traditional idea of the radiation belts includes a larger, more dynamic outer belt and a smaller, more stable inner belt with an empty slot region separating the two. However, a new study based on data from NASA’s Van Allen Probes shows that all three regions—the inner belt, slot region, and outer belt—can appear differently depending on the energy of electrons considered and general conditions in the magnetosphere. 2. At the highest electron energies measured—above 1 MeV—researchers saw electrons in the outer belt only. 3. The radiation belts look much different at the lowest electron energy levels measured, about 0.1 MeV. Here, the inner belt is much larger than in the traditional picture, expanding into the region that has long been considered part of the empty slot region. The outer belt is diminished and doesn’t expand as far in these lower electron energies. 4. During geomagnetic storms, the empty region between the two belts can fill in completely with lower-energy electrons. Traditionally, scientists thought this slot region filled in only during the most extreme geomagnetic storms happening about once every ten years. However, new data shows it’s not uncommon for lower-energy electrons—up to 0.8 MeV—to fill this space during almost all geomagnetic storms. Credit: NASA Goddard/Duberstein

Findings could impact how we protect technology in space

LOS ALAMOS, N.M., Feb. 23, 2016—The shape of the two electron swarms 600 miles to more than 25,000 miles from the Earth’s surface, known as the Van Allen Belts, could be quite different than has been believed for decades, according to a new studyof data from NASA’s Van Allen Probes that was released Friday in the Journal of Geophysical Research.
“The shape of the belts is actually quite different depending on what type of electron you’re looking at,” said Geoff Reeves of Los Alamos National Laboratory’s Intelligence and Space Research Division and lead author on the study. “Electrons at different energy levels are distributed differently in these regions.”
Read the complete article courtesy of Los Alamos National Laboratory

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