James Van Allen | Biography

James Van Allen is best known for his discovery of the radiation belts that encircle the earth. In addition, he designed the rockoon, or rocket balloon technique that enables rockets to be launched into outer space from mid-air rather than from the ground. Van Allen, whose interests included terrestrial electromagnetism and cosmic radiation, also helped develop the United States space program.

Born in Mount Pleasant, Iowa in 1914, Van Allen studied physics at both the Iowa Wesleyan college and the University of Iowa, where he earned his Ph.D. in 1939. Following a three year stint as a research fellow at the Carnegie Institution in Washington, he entered the Navy and served for four years as an ordinance and gunnery officer.

After World War II, Van Allen became the supervisor for the High Altitude Research Group and the Proximity Fuse Unit at Johns Hopkins University, where he investigated the conditions encountered by rockets and missiles during their entry into the stratosphere and the higher levels of the earth's atmosphere. In 1951 he was appointed a professor of physics at the University of Iowa, a post which later came to include astronomy as well. Between 1953 and 1954, Van Allen was engaged in Project Matterhorn, a study of thermonuclear reactions, and later, from 1957 to 1958, in the coordination of events for International Geophysical Year.

Van Allen's first research projects concerned cosmic radiation. Approximately 100 captured German V-2 rockets were shipped to White Sands Proving Ground to be tested. Van Allen used these missiles to carry scientific instruments that would measure the levels of radiation they encountered in their flight. In 1949 Van Allen pioneered what came to be known as the rockoon technique, involving the use of a balloon to lift a small rocket into the stratosphere prior to ignition, thereby eliminating the drag experienced by a rocket fired from the ground.

When the V-2 program came to an end, Van Allen, who had led the operation, was put in charge of the Aerobee rockets by which the V-2s were replaced. These rockets were capable of carrying 150 pounds (68 kg) of scientific payload to an altitude of 300,000 feet (91,500 m). Projects undertaken included investigating and measuring solar radiation, sky brightness, atmospheric composition, and auroras. The data Van Allen gathered showed that Newfoundland, an auroral zone, received a greater intensity of cosmic radiation than was expected, linking the aurora with a high count of cosmic radiation.

Explorer 1, the first American artificial satellite, was to be launched to coincide with International Geophysical Year in 1958, and Van Allen, who was responsible for fitting the satellite with scientific instruments, fixed it with a Geiger counter. The data returned showed that the counter registered increasing concentrations of cosmic rays until it went above 800 km, where no count was registered at all. This mystery continued until the experiment was repeated on Explorer 3, this time with a lead shield to protect the Geiger counter from the majority of rays as a test for Van Allen's hypothesis that sufficiently high levels of radiation were jamming the counter and causing it to register zero. The Geiger counter gave a normal reading, showing that there were indeed cosmic rays beyond 800 km.

After this, Van Allen proceeded to map the size and distribution of these radiation zones, and discovered that they took the form of two torroidal belts around the earth at the level of the equator. The particles making up the radiation belts were trapped in the Earth's magnetic field, spiraling about the magnetic lines of force from pole to pole, with an intensity that varied in relation to solar activity. These zones of intense radiation were named Van Allen belts and were taken into account when planning flight paths into outer space. Van Allen's discovery of the belts provided a new basis for investigation of upper-atmosphere phenomena, as well as contributing to the understanding of the mechanisms that generate aurorae.

For his many contributions, Van Allen has been honored with several prizes, including the prestigious National Medal of Science, awarded to him by President Reagan in 1987.