James Van Allen, American physicist and philosopher (died 2006)

James Alfred Van Allen was an American space physicist at the University of Iowa who was instrumental in establishing the field of magnetospheric research in space. His discovery of the Van Allen radiation belts in 1958, zones of energetic charged particles trapped by Earth's magnetic field, was the first major scientific finding of the Space Age. As principal investigator for scientific instruments on 24 Earth satellites and planetary missions, Van Allen provided the first in situ measurements of the magnetospheres of Jupiter and Saturn, pioneered the use of energetic particle absorption signatures to detect planetary rings and satellites, and carried out a multi-decade program of cosmic ray observations that established the radial gradient of galactic cosmic ray intensity from 1 AU to beyond 65 AU in the heliosphere.