Carol Mon Mar 04, 2013 9:43 am
March 4, 2013 – SPACE – Earth’s radiation belts were one of the first discoveries of the Space Age. A new finding published in today’s issue of Science shows that we still have much to learn about them. NASA’s twin Van Allen Probes, launched just last August, have revealed a previously unknown third radiation belt around Earth. “Even 55 years after their discovery, Earth’s radiation belts still are capable of surprising us,” said Nicky Fox, Van Allen Probes deputy project scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “We thought we knew the radiation belts, but we don’t.” Previous observations of the Van Allen belts dating back to the late 1950s have documented two distinct regions of trapped radiation surrounding our planet, known as the inner and outer radiation belts. Particle sensors aboard the twin Van Allen Probes quickly revealed to scientists the existence of a transient, third radiation belt. Scientists observed the third belt for four weeks before a powerful interplanetary shock wave from the sun annihilated it. Each of the two Van Allen Probes carries an identical set of five instrument suites that allow scientists to gather data on the belts in unprecedented detail. Key data for this discovery came from the Relativistic Electron Proton Telescope (REPT) instrument, part of the probes’ Energetic Particle, Composition, and Thermal Plasma Suite (ECT). “This is the first time we have had such high-resolution instruments look at time, space and energy together in the outer belt,” says Daniel Baker, lead author of the study and REPT instrument lead at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder. “Previous observations of the outer radiation belt resolved it as a single blurry element. When we turned REPT on just two days after launch, we clearly saw the new belt and a [gap] between it and the outer belt.” –NASA
http://science.nasa.gov/science-news/science-at-nasa/2013/28feb_thirdbelt/Published on Feb 28, 2013 - These two nearly identical spacecraft launched in August 2012 and with only six months in operation, they may well be rewriting science textbooks. The probes study the Van Allen belts, gigantic radiation belts surrounding Earth, which can swell dramatically in response to incoming energy from the sun, engulfing satellites and spacecraft and creating potential threats to manned space flight.
James Van Allen discovered the radiation belts during the 1958 launch of the first successful U.S. satellite. Subsequent missions have observed parts of the belts, but what causes the dynamic variation in the region has remained something of a mystery.
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