The University of Chicago News Office
Aug. 10, 2000 Press Contact: Steve Koppes
(773) 702-8366

John Alexander Simpson, Physicist, 1916-2000

University of Chicago Professor John Alexander Simpson, a scientific group leader for the Manhattan Project, co-founder of the Bulletin of the Atomic Scientists and pioneering physicist who flew the first cosmic-ray experiments to Mars, Jupiter, Mercury and Saturn, died Thursday, Aug. 31, at the University’s Bernard Mitchell Hospital of pneumonia and respiratory failure following open-heart surgery. He was 83.

“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. "With several generations of graduate students, he pioneered new areas of research ranging from outbursts of solar particle radiation to the origin and lifetime of cosmic-ray particles from nearby regions of the Milky Way. 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.”

Glenn Mason, a professor of physics at the University of Maryland, College Park, called Simpson "a towering figure in 20th century science.”

“In June he received the American Geophysical Union’s highest award, the William Bowie Medal, which shows how widely his contributions were appreciated in the science community, not only for the research he did, but also for his many contributions in areas of public policy," Mason said.

Simpson came to the University of Chicago in 1943, shortly after Enrico Fermi and his team achieved the first controlled nuclear chain reaction on campus as part of the top-secret Manhattan Project.

On Aug. 7, 1945, the day after the United States dropped the atomic bomb on Hiroshima, Simpson and his colleagues organized the Atomic Scientists of Chicago to campaign for the peaceful use of nuclear power under international control. Simpson served as the group’s first chairman. Along with two of his University of Chicago colleagues, Simpson stated the case in an article that filled two pages of the Oct. 29, 1945 issue of LIFE magazine. In December 1945, Simpson co-founded the Bulletin of the Atomic Scientists.

In late 1945, Simpson also became an unofficial adviser to U.S. Sen. Brien McMahon of Connecticut, who chaired the Senate Special Committee on the Control of Atomic Energy. Together they and others worked successfully to promote and develop the McMahon Act of 1946, which provided for the civilian control of atomic energy.

Simpson soon turned his attention to cosmic rays, subatomic particles that constantly bombard Earth from all directions at nearly the speed of light. He began studying cosmic rays shortly after World War II, first with instruments aboard B-29s, then aboard helium balloons and a naval vessel that sailed to the Antarctic to learn why their intensities varied widely.

In 1948, Simpson invented the cosmic ray neutron intensity monitor. By 1951 he had set up five monitoring stations from the city of Chicago to the magnetic equator in Peru, allowing him to use the Earth’s own magnetic field as an analyzer. All but the highest-energy cosmic rays are deflected into space near the equator, where the magnetic field is strong and nearly parallel to the Earth’s surface. But as the field becomes more vertical toward the poles, lower-energy particles are able to penetrate the atmosphere.

"When the sun is active, we get fewer cosmic rays here," said Eugene Parker, the S. Chandrasekhar Distinguished Service Professor Emeritus in Physics, Astronomy & Astrophysics at the University of Chicago. "John pointed out that this was probably due to magnetic fields varying in space. They had the effect of somehow eliminating the lower-energy cosmic rays here on Earth.”

During a spectacular solar flare in 1956, Simpson’s neutron monitors collected the first evidence pointing to the existence of the heliosphere, a region influenced by the sun’s magnetic field that extends far beyond the planets. During the International Geophysical Year in 1957-58, the neutron monitor became the standard for conducting cosmic-ray research. Today, the instrument remains a primary tool that scientists use to study cosmic rays at more than 50 monitoring stations around the world.

Simpson also used outer space as his laboratory to study the composition of cosmic rays and how they are accelerated by the sun’s magnetic and galactic fields. He established Chicago’s space research program in 1958 with Peter Meyer, Professor Emeritus in Physics, and a $5,000 allocation from the University. Starting with the Pioneer 2 satellite, launched in 1958, Simpson has served as the lead researcher for 34 instruments flown in Earth orbit and throughout the solar system, from Mercury to beyond Pluto.

Among the many students who studied under Simpson was Edward Stone, who received his doctorate from Chicago in 1964. As a doctoral student in the early1960s, Stone analyzed data from Simpson’s experiment aboard the Discoverer 36 satellite. Stone went on to serve as the project scientist for the Voyager mission to Jupiter, Saturn, Uranus and Neptune. He became director of JPL in 1991.

Another student of Simpson’s was Glenn Mason, who received his doctorate from Chicago in 1971. Mason is the lead scientist for NASA’s Solar Anomalous Magnetospheric Particle Explorer satellite. "A large number of his students are research faculty members around the country," Mason said. "His impact has been extremely broad.”

Simpson also influenced Parker’s own distinguished career at Chicago.

“He was always personally concerned about the junior people working with him," Parker said. "He’s the one who gave me my job here at Chicago in 1955, and when questions of my promotion came up in later years, he was the guy who pushed.”

Parker, a member of the National Academy of Sciences and a recipient of the National Medal of Science, is best-known for his prediction and naming of the solar wind, the stream of electrically charged particles emitted by the sun.

In his own research, Simpson and his team built the first cosmic-ray detector to visit Mars in 1965, the first to Jupiter in 1973, to Mercury in 1974 and to Saturn in 1979. Simpson’s instruments aboard the Pioneer 10 and Pioneer 11 spacecraft discovered the radiation belts of Jupiter and Saturn.

Cosmic-ray observations are still being collected by Simpson’s Cosmic Ray Experiment on the Eighth Interplanetary Monitoring Platform in Earth orbit and the Cosmic Ray and Solar Particle Experiment aboard the Ulysses spacecraft, which orbits the sun in a near-polar orbit. Simpson proposed the mission concept for Ulysses in 1959. Ulysses was the first spacecraft to leave the narrow orbital plane of the planets to make observations near the sun’s north and south poles.

“John has been extremely enterprising," Parker said. "More than any other person, I think, he has developed new schemes for making cosmic-ray measurements.”

Simpson’s creativity extended to other fields, most recently with the invention of a new way of detecting microscopic dust particles in space in the early 1980s. His newly invented detectors flew on the Soviet Union’s Vega 1 and Vega 2 missions to Halley’s Comet in 1986. These were the only U.S. instruments to encounter Halley’s Comet.

Simpson’s dust instruments continue to collect data on a variety of space missions. The Stardust mission, launched last year toward a 2004 rendezvous with Comet Wild-2, carries Simpson’s Dust Flux Monitor Instrument. The DFMI will measure the size of the dust particles that Stardust encounters and it will map their distribution around the comet’s nucleus.

Two other instruments related to the DFMI are components on NASA’s current Cassini mission to Saturn and on the Air Force’s unclassified Advanced Research and Global Observation Satellite. Simpson’s High Rate Detector on Cassini will collect and analyze dust particles found in interplanetary space and those that form the major components of Saturn’s rings.

The ARGOS space dust instrument has been measuring the mass, speed and trajectory of interplanetary dust particles and man-made space debris found in low-Earth orbit since its launch last year.

Simpson continued to work until his recent illness and was involved in interplanetary space missions scheduled to collect data for much of the current decade. Continuing his work will be his longtime associates, University of Chicago Senior Scientists Anthony Tuzzolino and Bruce McKibben, to whom Simpson had turned over the day-to-day operation of his experiments.

Simpson was born Nov. 3, 1916, in Portland, Ore. He received his bachelor’s degree from Reed College in Portland in 1940, then attended New York University, where he earned his master’s degree in 1942 and his doctorate in 1943. He served as a scientific group leader for the Manhattan Project at the University of Chicago from 1943 to 1946. He became an Instructor in Physics at the University in 1946, Assistant Professor in 1947, Associate Professor in 1949, Professor in 1954, Edward L. Ryerson Distinguished Service Professor in 1968, Arthur H. Compton Distinguished Service Professor in 1974 and Arthur H. Compton Distinguished Service Professor Emeritus in 1987. He also held appointments as Chairman of the Committee on Instruction in Biophysics from 1951 to 1952, and as Director of the Enrico Fermi Institute from 1973 to 1978.

Simpson served as president of the International Commission on Cosmic Radiation from 1965 to 1967. He held the Smithsonian Institution’s Martin Marietta Chair for Space Science History from 1987 to 1988.

His many awards include the Leo Szilard Lectureship Award from the American Physical Society, 1999; the first O'Ceallaigh Medal from the International Union of Pure and Applied Physics Cosmic Ray Commission and the Dublin Institute for Advanced Studies, 1999; the Arctowski Medal and Prize of the National Academy of Sciences, 1993; the Bruno Rossi Prize of the American Astronomical Society for fundamental research in high energy astrophysics, 1991; the COSPAR Award of the United Nations for Scientific Research in Space, 1990; the NASA Medal for Exceptional Scientific Achievement, 1974; the Gagarin Medal for Space Exploration, from what was then called the U.S.S.R Academy of Sciences, 1986; and the Quantrell Award for Excellence in Undergraduate Teaching at Chicago, 1980.

He also was elected to the National Academy of Sciences in 1959 and to the American Philosophical Society in 1996.

Survivors include his wife, Elizabeth Simpson of Chicago; two children from his first marriage, Mary Ann Smith of Bangor, Mich., and John A. Simpson of Nahant, Mass.; three grandchildren, Ryan and Christopher Smith of Bangor and John A. Simpson of Nahant. Simpson was divorced from his first wife, Elizabeth Hiltz Simpson, in 1977. She died in 1990.

The family will hold a private ceremony. Arrangements for a memorial service at the University are pending.
Last modified at 05:29 PM CST on Wednesday, September 06, 2000.

University of Chicago News Office
5801 South Ellis Avenue - Room 200
Chicago, Illinois 60637-1473
(773) 702-8360
Fax: (773) 702-8324
Contact Us