Van Allen Probes Probe Earth's Radiation Belts


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NASA this week revealed that the early findings from its Van Allen Probes, which are uncovering the mysteries of Earth's radiation belts, are already helping researcher's determine just how much influence the sun has over Earth's magnetosphere. The probes, launched back in August, are orbiting in areas populated by high-energy and hazardous particles created by the magnetosphere.

“The sun has been a driver of these systems more than we had any right to expect,” said Daniel Baker, Principal Investigator for the Van Allen Probes Relativistic Electron Proton Telescope (REPT) at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado. “We’re seeing brand new features we hadn’t expected. We expected to see a fairly placid radiation belt system. Instead, we see that the belts have been extraordinarily active and dynamic during the first few weeks. We’re looking in the right places at the right times.”

Events from the sun, such as solar eruptions and plasma ejections have caused "dramatic" changes in the radiation belts. The Van Allen Probes have measured these changes using identical sets of five instrument suites. Measurements using the Electric Fields and Waves Suite (EFW) and the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) are helping researchers understand how fields and waves of electricity and magnetism affect charged particles within the belts.

“The electric field and magnetic field measurements on the Van Allen Probes are the best ever made in the radiation belts,” said Craig Kletzing, principal investigator for EMFISIS at the University of Iowa. “For the first time, we’ve been able to see how long intense low frequency electric fields and waves at the edge of the radiation belts can last - sometimes for over five hours during geomagnetic storms. Before, it was like we could see a car zoom past, but not see anything about the details. Now, we can see what color the upholstery is.”

NASA also revealed that the Van Allen Probes have been taking a beating in orbit. The inner radiation belt where they orbit is also where the most hazardous and energized particles orbit. The probes were built to be tough, and are discovering that the density of these particles varies at different altitudes, using their Relativistic Proton Spectrometer (RPS) instruments.

(Image courtesy JHU/APL)