Nuclear physicist who influenced space exploration

John A. Simpson ’40

John A. Simpson ’40, LHD ’81, August 31, 2000, in Chicago, of complications following open heart surgery.

He was a pioneering nuclear physicist and astrophysicist whose work has been instrumental in space exploration over the last 40 years. After earning a PhD in physics from New York University in 1943, he joined the faculty of the University of Chicago Institute for Nuclear Studies and physics departmemt, where he worked on the Manhattan Project researching atomic weapons. After the war, became a leader in the campaign for the peaceful use of atomic energy under civilian control, and he was a cofounder of the Bulletin of the Atomic Scientists, a professional publication dedicated to the prevention of nuclear war.

His career at the University of Chicago spanned over 50 years. He directed the Enrico Fermi Institute in 1973–78 and was professor of physics until his retirement in 1987 as the A.H. Compton Distinguished Service Professor, Emeritus. He continued to work at the institute until shortly before his death. His research on cosmic rays led to his invention of the cosmic ray neutron intensity monitor, which, in 1956, collected the first evidence demonstrating the existence of the heliosphere.

John and his team built the first cosmic-ray detectors for missions to visit Mars in 1965, Jupiter in 1973, Mercury in 1974, and Saturn in 1979. Simpson’s instruments aboard the Pioneer 10 and Pioneer 11 spacecraft discovered the radiation belts of Jupiter and Saturn. His creativity also extended to other fields, most recently with the invention of a new way of detecting microscopic dust particles in space in the early ’80s.

“With instruments almost continuously in space for the last 40 years, John Simpson was always probing the frontiers of the solar system for new knowledge," said Edward C. Stone, director of NASA’s Jet Propulsion Laboratory. "His contributions, however, extended beyond deep space and included broader national and local contributions that reflected his dedication to the importance of the role of science and the university in society.” He received numerous awards and citations during his career, most recently the William Bowie Medal from the American Geophysical Union in June, 2000.

Survivors include his wife, a son and a daughter from his first marriage, and three grandchildren.

Appeared in Reed magazine: February 2001