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The Van Allen Radiation Belt is the ring of high energy particles that surround the Earth. It is held in place by the Earth’s magnetic field. The Van Allen Radiation Belt is associated with geomagnetic storms and the Aurora phenomenon that is often seen near the Earth’s poles.
The Van Allen Radiation Belt is more of a torus than a ring. The belt is made of both an inner and outer ring. The inner ring is mostly made up of low energy electrons and protons while the outer ring is mostly high energy electrons. The Van Allen Belt is made up of the leavings of cosmic radiation interacting with the upper atmosphere and geomagnetic storms. Its shape is also largely effected by the solar winds. With the sunward side of the Van Allen radiation belt being much shorter than the side facing away which stretches to over three Earth diameters.
The Van Allen Radiation Belt is of major concern for spaceflight. First the high energy particles often damage solar arrays and electrodes. To this purpose deep space probes and satellites need to be built to withstand the barrage of high energy particles. On average a satellite that is shielded with 3 mm of aluminum will still receive 2500 rem of radiation a year. The real challenge is for manned space flight. The space shuttle and other manned space craft have to be shielded to withstand radiation just outside the Earth’s atmoshpere. For long term trips such as Mars designers and engineers will need to find ways to shield manned space craft from the much higher levels of radiation produced by the Van Allen belt and the cosmic radiation that generally whips through the universe. This is one of the signature challenges that remain for deep space manned exploration since long term exposure to radiation of such levels is lethal to humans.
If you found this article interesting there are other pieces on Universe Today that you will find interesting. There is a great article on space radiation. There is another intriguing article on solar radiation.
If you want to learn more about the Van Allen Radiation Belt you can check out the Ask an Astrophysicist NASA page. There is also a NASA education web page that goes into more detail about radiation belts.
You should also listen to Astronomy Cast. Episode 163 is about Auroras.