James Van Allen (1914-2006), US astrophysicist, holding a model of the rocket launcher Juno 1 with the satellite Explorer 1 on the nose cone. He is pointing to a map of the orbital path for this satellite. In 1958, Allen argued for the use of a Geiger counter (radiation detector) on Explorer I, the first American scientific satellite. The counter detected belts of ionised particles trapped by the Earth's magnetic field. These belts were named Van Allen belts after him. Van Allen retired in 1985 and was awarded the Crafoord Prize for Astronomy in 1989.