Early in 1958, instruments on the space satellites Explorer I and Explorer III revealed the presence of radiation belts, enormous populations of energetic particles trapped in the magnetic field of the earth. Originally published in 1983 but long out of print, "Origins of Magnetospheric Physics" tells the story of this dramatic and hugely transformative period in scientific and cold war history. Writing in an accessible style and drawing on personal journals, correspondence, published papers, and the recollections of colleagues, space pioneer James Van Allen documents a trail-blazing career in space history. "Origins of Magnetospheric Physics" was his first book; for this paperback edition he wrote a new preface to introduce his "tale of curiosity, exploration, and discovery" to another generation of readers.