James Alfred Van Allen (September 7, 1914 – August 9, 2006) 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. A member of the National Academy of Sciences (elected 1959), the American Philosophical Society, and the American Academy of Arts and Sciences, Van Allen received the National Medal of Science (1987), the Crafoord Prize from the Royal Swedish Academy of Sciences (1989), the Gold Medal of the Royal Astronomical Society (1978), and the Vannevar Bush Award (1991). Time magazine named him one of its Men of the Year in 1960. He led the scientific community in putting research instruments on space satellites and was a leading advocate for unmanned planetary exploration, chairing the Outer Space Panel that developed the scientific rationale for the Pioneer 10 and Pioneer 11 missions to the outer planets. He was also an outspoken critic of human spaceflight programs, arguing that robotic spacecraft yielded far greater scientific returns per dollar spent.
Early life and education James Van Allen was born on September 7, 1914, on a small farm near Mount Pleasant, Iowa. He was fascinated by mechanical and electrical devices from childhood and was an avid reader of Popular Mechanics and Popular Science. Van Allen earned his B.S. from Iowa Wesleyan College in 1935, followed by an M.S. (1936) and Ph.D. (1939) from the University of Iowa, where he studied nuclear physics under Alexander Ellett. A fellowship at the Carnegie Institution in Washington, D.C. broadened his research into geomagnetism, cosmic rays, auroral physics, and the physics of Earth's upper atmosphere.
World War II In August 1939, Van Allen joined the Department of Terrestrial Magnetism (DTM) of the Carnegie Institution as a research fellow. Beginning in 1940, he worked under Section T of the National Defense Research Committee (NDRC) on the development of photoelectric and radio proximity fuzes, detonators designed to increase the effectiveness of anti-aircraft fire. When this work was transferred to the newly created Applied Physics Laboratory (APL) of Johns Hopkins University in April 1942, Van Allen continued there, improving the ruggedness of vacuum tubes used in gun-battery fusing systems. Commissioned as a U.S. Navy lieutenant in November 1942, Van Allen served 16 months on South Pacific Fleet destroyers, instructing gunnery officers and field-testing the then-secret proximity fuses. He was assistant staff gunnery officer on the battleship USS Washington during the Battle of the Philippine Sea (June 19–20, 1944) and was awarded four battle stars. He was promoted to lieutenant commander in 1946.
High-altitude research and Rockoons (1946–1954) Discharged from the Navy in 1946, Van Allen returned to APL, where he organized a team to conduct upper-atmosphere experiments using captured German V-2 rockets. He drew the specifications for the Aerobee sounding rocket and headed the committee that secured U.S. government funding for its production. The first instrument-carrying Aerobee, launched March 5, 1948, from White Sands, New Mexico, reached an altitude of 117.5 km carrying cosmic radiation instruments. Van Allen chaired the Upper Atmosphere Rocket Research Panel from 1947, coordinating early American high-altitude research. In 1951, Van Allen accepted the position of head of the physics department at the University of Iowa. There he developed the Rockoon, a balloon-rocket combination that lifted small rockets on balloons to approximately 16 km altitude before firing them higher, a low-cost technique for reaching altitudes inaccessible to ground-launched sounding rockets alone. In 1953, Rockoons fired off Newfoundland provided the first hint of radiation surrounding the Earth. In 1954, Ernst Stuhlinger visited Van Allen (then on sabbatical at Princeton) to discuss an unofficial satellite concept being developed by Wernher von Braun's group at the Army Ballistic Missile Agency. Van Allen expressed keen interest in using such a satellite for a worldwide survey of cosmic ray intensity above the atmosphere (Project Orbiter).
International Geophysical Year and the discovery of the radiation belts
Van Allen played a catalytic role in the International Geophysical Year (IGY, 1957–58). In 1950, he hosted a gathering of scientists including Sydney Chapman, Lloyd Berkner, and S. Fred Singer at his home in Silver Spring, Maryland, at which the idea of a worldwide geophysical year was proposed. This concept grew into the IGY and, ultimately, the Space Race. Van Allen chaired a January 1956 symposium at the University of Michigan on "The Scientific Uses of Earth Satellites," at which 33 scientific proposals were presented. His Iowa group began preparing cosmic ray instruments for both Rockoon and Vanguard flights, and through what he later called "preparedness and good fortune," these instruments were available for the 1958 Explorer and Pioneer IGY launches. On January 31, 1958, the first American satellite, Explorer 1, was launched into orbit carrying a cosmic ray experiment designed by Van Allen and his graduate students George H. Ludwig and Carl McIlwain, with satellite deployment supervised by Ernst Stuhlinger. The single Geiger counter on Explorer 1 returned confusing data, with periods of normal counting rates interspersed with intervals of zero counts. The puzzle was resolved after Explorer 3 (launched March 26, 1958) carried a miniature tape recorder that captured complete orbital data: the zero-count intervals occurred when the instrument was saturated by unexpectedly intense radiation, producing a null response.
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