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Van Allen Belts - Discovery Of The Radiation Belts Of Earth, Description, Related Geophysical Effects, Radiation Belts Of Other Planets - Artificial radiation belts, Limitations on space flight, Two common misperceptions

altitude flights bursts magnetic

Radiation belts are enormous populations of energetic, electrically charged particles—principally protons and electrons—trapped in the external magnetic field of a planet. Durable radiation belts exist at the planets Earth, Jupiter, Saturn, Uranus, and Neptune but not at Mercury, Venus, or Mars.

Nine artificial radiation belts of Earth were produced during the period 1958-62 by the injection of electrons from radioactive nuclei produced by United States and USSR nuclear bomb bursts at high altitudes. These experiments made important contributions to understanding the natural belts. Since 1962 such high altitude bursts have been prohibited by international treaty.


The inner radiation belt imposes an altitude ceiling on the region around Earth within which orbital flights of humans and animals can be conducted without exposing the occupants to excessive or fatal radiation exposures. Prolonged flights of human crews above an altitude of about 250 mi (402 km) are unsafe though rapid traversals of the radiation belts requiring only a few hours (as in the Apollo missions to the Moon) result in moderate exposures.


Contrary to some common statements, trapped particles are not radioactive. Rather they are mainly ordinary electrons and protons such as those accelerated in high energy physics laboratories. Radiation belts do not shield Earth's surface, though the magnetic field deflects some cosmic rays away from Earth. The atmosphere acts as an effective shield against many solar and other radiations that impinge on it.


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about 9 years ago

noticed there was no mention of an experiment conducted by NASA for the Van Allen Radiation belt conducted on one of the Mercury flights. Walley Shnitger, Brian Cambell Larry Conley and Gary Conley designed and built this device flown on a mercury flight to map the Radiation belt through the sub orbital flight. This test was unique in that it was designed , built ,tested and calibrated in less than 6 weeks. It was delivered to Cape Canaveral the evening before the successful flight operation.

Television News programs carried the story of the experiment and displayed the device moc-up.



The company that supplied the instrument to JPL was:

Science Systems Inc.

Costa Mesa CA