Third Radiation Belt (Van Allen Radiation Belts)
The Van Allen radiation belts, discovered in 1958, with instruments aboard NASA's Explorer 1 spacecraft have, long intrigued scientists. Even 55 years after the discovery of Van Allen belt, the Earth's radiation belts still are capable of surprising us and still have mysteries to discover and explain. NASA's particle detection instruments aboard the twin Van Allen probes has discovered a previously unknown third radiation belt around the Earth, revealing the existence of unexpected structures and processes within these hazardous regions of space. Previous observations of Earth's Val Allen belts, named after their discoverer, James Van Allen, have long documented two distinct regions of trapped radiation surrounding our planet. These belts are affected by solar storms and space weather and can swell dramatically. The inner belt, stretching from about 1,500 to 12,500 kms above Earth's surface, is fairly stable.
However, the outer ring, spanning 18,750 to 30,000 kms, can swell up to 100 times its usual size during solar storms, engulfing communications and research satellites, bathing them in harmful radiation. When this occurs, they can pose dangers to communications and GPS satellites as well as human in space.
According to John Grunsfeld, NASA's associated Administrator for Science, "the advances technology in the Van Allen probes have allowed scientists to see in unprecedented details on what causes charged particles to change, and how these processes to change, and how these processes affect the upper reaches of Earth's atmosphere. The new high-resolution observations by the Relativistic Electron Proton Telescope (REPT) instrument, part of the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) aboard the Van Allen Probes, revealed there can be three distinct, long lasting belt structures with the emergence of a second empty slot region, or space, in between.
Scientists observed the third belt before a powerful interplanetary shock wave from the sun annihilated it. Observations were made by scientists from institutions including LASP; NASA's Goddard Space Flight Laboratory, and the institution for the study of Earth, Oceans, and Space at the University of New Hampshire. The Van Allen Probes are the second mission in NASA's Living with a Star Program to explore aspects of the connected sun-Earth system that directly affect life and society. Goddard's small solid-state telescope, Compact Relativistic Electron and Proton Telescope (CREPT), will measure energetic electrons and protons in Earth's Van Allen Belts. CREPT measurements will give scientists a better understanding of the physics of how the radiation belts lose electrons by a process known as electron micro-bursts (a mechanism by which the outer belt loses electrons).
