Magnetoplasmadynamcis, NASA history collection

: Schematic drawing of the Van Allen Radiation Belts. This chart was part of a briefing used by Magnetoplasmadynamcis (MPD) researchers. Van Allen developed a theory "that the earth's magnetic field trapped charged subatomic particles within certain regions. Experiments aboard subsequent exploratory rockets and spacecraft indicated with a high degree of certainty that more than one radiation belt in fact enveloped the earth. The intensity of the belts varied with their distance from the earth. The zone of the most intense radiation began at an altitude of approximately 1000 kilometers." "The discovery of what immediately came to be known as the Van Allen radiation belts inspired a wide range of fundamental new investigations. Within months, scientists around the world realized that surrounding the earth was a vitally important magnetic region of still unknown character, shape, and dimension where ionized gases--plasmas--exerted a strong force. They dubbed this mysterious region "the magnetosphere." In the exciting but highly speculative early days of magnetospheric physics, this region was alternately described as "a high region of the earth's atmosphere" or as a "low or bordering region of space.
NASA Identifier: L61-6169