James A. Van Allen (1914–2006)

NEWS & VIEWS NATURE|Vol 443|14 September 2006

OBITUARY James A. Van Allen (1914–2006)

Magnetospheric and space physicist, discoverer of the eponymous belts.

James A. Van Allen, who died in Iowa City When passing over terrestrial on 9 August, was a native of Iowa — he was receiving stations, it sometimes born in the small town of Mount Pleasant on transmitted the expected 7 September 1914 — and lived and worked cosmic-ray counting rates, and there for most of his life. But his influence, as at other times did not count at a founding father of magnetospheric physics all. A similar instrument on the and world-renowned leader in the scientific Explorer 3 spacecraft carried PARADE/GETTY PICTORIAL exploration of space, extended far beyond a tape recorder that could the boundaries of his home state. record the counting rate for After attending both high school and the an entire orbit. This revealed Iowa Wesleyan College in Mount Pleasant, that the periods of apparent Van Allen went to the University of Iowa in non-operation were caused Iowa City, where he graduated with a PhD by extremely intense charged- in physics in 1939. Following a spell in the particle radiation, thousands department of terrestrial magnetism at the of times more intense than the Carnegie Institution in Washington DC, cosmic-ray background, that Van Allen moved shortly after the outbreak of were simply saturating the the Second World War to the Applied Physics counter. The Van Allen belts Laboratory of Johns Hopkins University in — two doughnut-shaped regions Silver Springs, Maryland. There he worked of energetic charged particles to develop proximity fuses that allowed surrounding Earth — had been anti-aircraft shells to detonate automatically discovered. when reflected radio waves indicated the This entirely unexpected find approach of a target. When the development attracted worldwide attention. phase of this project was finished, he was Van Allen and his colleagues space research, including the National Medal commissioned as a lieutenant in the US Navy soon showed that the particles of the of Science in 1987, and the Crafoord prize and sent to the Pacific to test the fuses under radiation belt — mainly protons in the inner — awarded by the Royal Swedish Academy combat conditions. For this assignment, he belt and electrons in the outer belt — were of Sciences in disciplines outside the Nobel received four combat stars. trapped in stable, long-lived orbits by Earth’s prize categories — in 1989. After the war, back initially at Johns magnetic field. Over the nearly 50 years Van Allen was also an outstanding teacher Hopkins, and from 1951 as head of physics at since the discovery of the belts, the study of and mentor. He routinely taught a large, the University of Iowa, Van Allen pioneered this trapped radiation and its many effects, very popular undergraduate course in the use of Geiger tubes to measure cosmic such as magnetic storms and auroral light astronomy, and placed a strong emphasis rays at high altitudes. These tubes were emissions, has blossomed into a wide field on student involvement in his research. initially attached to captured German V-2 known as magnetospheric physics. Many of his 34 PhD and 48 MSc students and US Aerobee rockets, but Van Allen soon Not content with his pioneering work on went on to become leaders in magnetospheric developed his own low-cost, balloon-borne Earth’s magnetosphere, Van Allen extended his and space physics. That in turn gave rocket — which he called a rockoon — to research to other planets. He and his colleagues university-based research a leading role carry out the studies at similar altitudes. built similar Geiger-tube instrumentation in the US space programme, a role that The first comprehensive latitudinal survey for the Mariner 2 and 4 flights to Venus and endures today. of cosmic-ray intensities above Earth’s Mars, respectively, and the Pioneer 10 and 11 Van Allen’s influence on his profession atmosphere followed, using a series of rockets flights to Jupiter and Saturn. Although Venus was immense. He served on many local and launched from ships as part of the 1957–58 and Mars did not have radiation belts, Jupiter national scientific advisory committees. International Geophysical Year. and Saturn were shown to have very large A strong proponent of robotic spacecraft, During this period, Van Allen was also magnetospheres. As Pioneers 10 and 11 moved he became a persistent critic of human engaged in the development of an artificial outward from the Sun, they also performed spaceflight, especially of the space shuttle and satellite as part of the navy’s Vanguard the first studies of the entry of cosmic rays into the International Space Station. He regarded programme. On 4 October 1957, before these the heliosphere. This is the region around the these missions as inordinately expensive plans came to fruition, the Soviet Union Sun in which the solar wind — the stream of relative to the results obtained. launched the world’s first satellite, Sputnik 1. charged particles given off by its surface — has For his qualities of humanity and In the ensuing frantic catch-up effort, Van a controlling influence. leadership in space science, James Van Allen Allen was asked to put his Geiger-tube During his career, Van Allen published will be missed by all who knew and worked instrumentation on a spacecraft, Explorer 1, prolifically, producing more than 275 with him. to be carried by a rocket developed by research papers and several books, one of Donald A. Gurnett Wernher von Braun. The spacecraft launched which, Origins of Magnetospheric Physics, Donald A. Gurnett is in the Department of successfully on 31 January 1958. gives a detailed account of the early days of Physics and Astronomy, University of Iowa, Strapped to Explorer 1, the Geiger tube that field. He received many honours and Iowa City, Iowa 52242-1479, USA. produced what seemed to be erratic results. prizes for his pioneering work in the field of e-mail: [email protected]