John Alexander Simpson (physicist)

John Alexander Simpson (born November 3, 1916 in Portland , Oregon , † August 31, 2000 in Chicago , Illinois ) was an American astrophysicist and physicist . He is known as a designer of measuring instruments for space probes.

Life

Simpson studied at Reed College with a bachelor's degree in 1940 and at New York University with a master's degree in 1943 and his doctorate in 1944 with Serge Korff. From 1943 he was active in the Manhattan Project in Chicago ( Metallurgical Laboratory ), in which he developed measuring instruments for high radiation doses as a group leader. He stayed at the University of Chicago , where he became a professor at the Enrico Fermi Institute in 1954 . 1973 to 1978 he was its director. In 1986 he retired.

As early as 1946 he was concerned with measuring instruments for cosmic radiation, including the Neutron Monitor (1948), with which he observed temporal and spatial variations of cosmic radiation in several countries ( Peru , Mexico , Colorado , in addition to Chicago). With the Sputnik shock (1957) he also began to develop instruments for satellite observation and a first experiment he developed was launched into space in 1958 ( Pioneer ). To this end, he founded the Laboratory for Astrophysics and Space Research (LASR) at the University of Chicago in 1962. In the mid-1960s, his cosmic ray detectors were on a Mars mission, in 1973 on Jupiter ( Pioneer 10 ), 1974 on Mercury ( Mariner 10 , also Venus flyby) and in 1979 on Saturn (flyby Pioneer 11 ). This enabled electrons accelerated to relativistic energies (3 to 30 MeV) to be detected at Jupiter (still at a distance of 1 AU from Jupiter), and a magnetic field on Mercury. His instruments were also involved in the observation of solar flares ( Ulysses ) - and on the Cassini probe to Saturn.

His Dust Flux Monitor (developed with AJ Tuzzolino) was used on Russian missions (Vega 1,2) to Halley's Comet in 1986. For this he received the Russian Gagarin Medal.

In 1991 he received the Bruno Rossi Prize . He was a member of the National Academy of Sciences (1959), the American Academy of Arts and Sciences (1971) and the American Philosophical Society (1996). In 2000 he received the William Bowie Medal from the American Geophysical Union . In 1999 he received the Leo Szilard Lectureship Award .

In 1946 he was the founding chairman of the Bulletin of the Atomic Scientists . Immediately after the first atomic bombs were dropped, he warned against their further military use and advocated the civil use of nuclear energy. For a while in 1945 he was the unofficial advisor to the US Senator Brien McMahon from Connecticut , after whom the McMahon Act (1946) is named, and was given leave of absence from the university for this.

He was married twice and had a son and daughter from his first marriage.

Web links

• Obituary in Guardian 2000
• Obituary in the New York Times
• Obituary by Eugene Parker at the National Academy of Sciences
• Simpson Papers, University of Chicago