U.S. Explorer 1 in early 1958 discovered radiation belt around the Earth. Holding a model of the satellite in celebration after its successful orbiting: (left to right) William H. Pickering, former director of JPL, which built and operated the satellite; James A. van Allen, center, of the State University of Iowa, designed and built the instrument on Explorer that detected the radiation that circles Earth; and at right, Wernher von Braun, leader of the Army's Redstone Arsenal team. Credit: NASA/JPL
