From time to time, something causes increased radiation

Jul 16, 2007 08:48 GMT  ·  By

Solar wind is a form of plasma that is constantly ejected from its upper atmosphere and continuously bombards space all around with high-energy electrons and protons that escaped the immense gravity of the Sun in a process that is yet to be fully understood.

Fortunately, Earth was a wonderful defense mechanism that usually works well at protecting us from normally lethal radiation, the Van Allen radiation belt. This is a volume of space around our planet, made up of an outer belt and an inner one, maintained by its magnetic field that traps most of the high-energy particles, which would otherwise reach the surface.

But, from time to time, actually around once every month, there is a strange increase in the radiation levels, a sudden spike that creates extremely strong streams of electrons that produce damage to electrical girds and appliances on Earth and can affect the DNA of an unfortunate astronaut caught outside the shuttle or the space station.

This can affect satellites, can disturb GPS systems and can induce unexpected currents in the electrical grid. What causes this strange acceleration? The most recent quest for the solution of this old puzzle was taken by a team of scientists at Los Alamos National Laboratory in New Mexico that has examined data collected over the past few years from the laboratory's instruments mounted on five different satellites in geosynchronous orbit at various altitudes.

They found only a partial answer: the phenomenon is caused by an unknown acceleration process inside the Van Allen belts. The interesting part of the study is the fact that it shows how the Sun is not the only one responsible for the sudden increase in radiation hitting Earth, although many times it coincides with the incidence of solar storms.

Only that there are some cases where the energy of the particles increased very quickly near the center of the Van Allen belts without the influence of an outside source, a fact never before proven. "We were trying to assemble a snapshot of the missing data pieces," says Reiner Friedel, astrophysicist and co-author of the study. And using the array of satellites "allowed us to see things that we couldn't see with a single satellite."

It is hoped that a new NASA mission, the Radiation Belt Storm Probe, to be launched in 2012, will solve the rest of the problem by identifying the mysterious force pushing electrons toward the Earth with no apparent reason, causing a temporary failure in Earth's defense mechanism.