Findings

Science  01 Mar 2013:
Vol. 339, Issue 6123, pp. 1019
  1. Another Radiation Belt for Van Allen

    CREDIT: JOHNS HOPKINS UNIVERSITY APPLIED PHYSICS LABORATORY USING REPT DATA FROM LASP

    More than 50 years after the United States's first satellite, Explorer 1, discovered two donuts of radiation stacked over Earth's equator, a pair of NASA satellites has stunned space physicists with the discovery of a third Van Allen radiation belt (albeit a temporary one). Theorists did not see it coming, and none of the instrumented satellites flying since the 1958 discovery could reveal the new belt's highly energetic charged subatomic particles zipping about at near the speed of light.

    Addressing that shortcoming, NASA launched the twin Van Allen Probes on 30 August last year. Anxious to compare their readings with those from NASA's SAMPEX satellite, due to fall out of orbit soon, team members turned on their high-energy electron detector just 4 days after launch. Good thing or they would have missed a third belt of exceptionally energetic electrons (middle red crescent in cross section of belts) that appeared 2 days after turn-on and abruptly disappeared on 1 October. These observations, published online this week in Science, should help scientists track how disturbances blasting out from the sun rattle Earth's magnetic field (gray lines), accelerating particles until they reach the energies of a Van Allen belt.

Log in to view full text

Navigate This Article