The discovery should help scientists improve forecasts for how the radiation belts change under particular circumstances, information that has a practical implication for the design and operation of satellites.
"Those kinds of radiation environments (around Earth) have not been taken into account in some of the modeling for (spacecraft) design and other purposes. That will have to be factored in," space weather researcher Louis Lanzerotti, with the Center for Solar-Terrestrial Research at New Jersey Institute of Technology, told Discovery News.
The inner Van Allen belt begins about 650 miles above Earth and extends to about 8,000 miles, although sometimes it dips as low as 125 miles -- well within the region where the International Space Station flies.
The outer belt begins at an altitude of about 8,000 miles and extends to about 26,000 miles, encompassing an area where communications and GPS satellites operate.
Particles in the belts come from the solar wind and get caught up in the tail part of Earth's magnetosphere. By some unknown process, some of those particles are accelerated, forming a seed population which gets trapped in outer fringes of Earth's magnetic field regions. Those particles then undergo another process that drives them deeper in the magnetosphere, resulting in particles that move at near light speed. The goal of the Van Allen Probes mission is to unravel these processes, which has implications far beyond understanding the space environment around Earth.