Radiation belts mystery solved by new observations from Van Allen Probes?

December 5, 2013 by  
Filed under Solar Energy Tips

According to a December 4 news release from NASA’s Goddard Space Flight Center, the twin Van Allen Probes were launched by the space agency in August 2012 to differentiate between the many different electromagnetic waves that may be accelerating the particles in the belts to near-light speed.

Following a thorough analysis of the observations from the mission, scientists discovered – in images of unprecedented resolution – that more low frequency waves are present than largely accounted for, which offers one possible explanation for what is speeding the particles up so fast.  The results appear in the November 19 issue of Nature Communications, in an article entitled, “Discovery of the action of a geophysical synchrotron in the Earth’s Van Allen radiation belts.”

“These observations show some of the most beautiful examples of the low frequency waves that we’ve seen,” said David Sibeck, mission scientist for the Van Allen Probes at NASA’s Goddard Space Flight Center.  ”It’s important to include all these different types of waves into our models to best understand what drives the complex radiation belts.”

The radiation belts are undeniably complex, as they change shape and size in response to incoming energy and particles from the Sun.  In extreme instances of such space weather, nearby satellites can be overwhelmed by the belts, potentially charging the spacecraft or even short-circuiting internal electronics.  Superior understanding of the processes going on inside the belts can ultimately help protect orbiting spacecraft from damage.

“Essentially near-Earth space is filled with a basic magnetic field which can be perturbed by a modest solar wind from a very typical star,” said Ian Mann, first author on the paper and a space scientist at the University of Alberta in Canada.  ”When compared with the much more exotic astrophysical objects out in the universe, Earth’s system doesn’t initially look like it should accelerate particles up to such incredible speeds.  But something is happening right above our heads that is a very efficient, planetary-scale accelerator, and scientists have been trying to understand this ever since the belts were first discovered.”

The Van Allen Probes data also show that the acceleration mechanism acts much faster than standard models of ultra-low frequency wave interactions – data that could alter scientists’ understanding of belt dynamics.   As the Van Allen Probes remain in orbit through the Van Allen Belts, they are collecting information about a mass of other waves and particle movements as well, all of which go toward improving models of this region.

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