Stanford Report Online

Stanford Report, May 2, 2001
Solar physicist Art Walker dies at 64; pioneer in X-ray optics


Arthur Bertram Cuthbert Walker II, professor of physics and applied physics at Stanford since 1974 and pioneer in the use of X-rays and thin films to study the solar corona, died April 29 at his home on campus after a long battle with cancer. He was 64.

A public viewing is scheduled for Wednesday, May 2, from 7 to 9 p.m. at Roller, Hapgood & Tinney funeral chapel at 980 Middlefield Road in Palo Alto. A memorial service is scheduled for Thursday, May 3, from 3 to 4 p.m. in Stanford Memorial Church. A reception will follow at the Stanford Faculty Club.

Arthur Bertram Cuthbert Walker II, professor of physics and applied physics, at his home on campus shortly after being appointed by President Ronald Reagan in 1986 to serve on the commission that investigated the space shuttle Challenger explosion. Courtesy Victoria Walker.

"[Walker] was best known for developing, with [materials scientist] Troy Barbee, a whole new set of X-ray optics with which the two of them formed some wonderful and scientifically important images of the sun," said Malcolm Beasley, dean of the School of Humanities and Sciences and a colleague of Walker's in the Applied Physics Department. "Art was also a leader of the community of African American physicists, and a very, very respected conscience of us all in diversifying the academy -- not to mention a role model to many students."

Largely due to Walker's efforts, Stanford led the nation's major research universities in educating graduate students from underrepresented groups in physics. Astronaut Sally Ride, America's first woman in space, was among Walker's graduate students. The month before his death, he presided over the National Conference of Black Physics Students, hosted this year at Stanford.

Walker's recommendations to Congress were instrumental in creating a national solar observatory. In 1986, President Ronald Reagan appointed him to serve on the commission that investigated the space shuttle Challenger explosion and ultimately concluded that the disaster was preventable.

Walker was born in Cleveland on Aug. 24, 1936. He received a baccalaureate degree in physics with honors from Cleveland's Case Institute of Technology in 1957. He earned a master's degree in 1958 and doctorate in 1962 from the University of Illinois with a dissertation on the use of radiation to produce the particles that bind protons and neutrons together in the atomic nucleus.

Walker joined the U.S. Air Force in 1962 as a first lieutenant and was assigned to the Air Force Weapons Laboratory, where he developed instrumentation for an experiment that involved rocket launch of a satellite to measure Van Allen belt radiation in the Earth's magnetic field.

Upon completing his military duty in 1965, he joined the Space Physics Laboratory of the Aerospace Corporation, where for nine years he conducted pioneering physics experiments to study the sun and upper atmosphere of the Earth.

After arriving at Stanford, Walker directed the student observatory and taught astronomy courses including the popular Applied Physics 15 ("The Nature of the Universe") and Physics 50 ("Observational Astronomy").

In the 1980s, senior research associate Troy Barbee at Stanford's Center for Materials Research created multilayered thin films that could capture images produced by hot solar gas so energetic that it spewed radiation in the extreme ultraviolet end of the spectrum. In 1987, Walker used these materials to develop telescopes and complex instrumentation, which he mounted on rockets and launched into space to capture the first detailed pictures of the sun's outermost atmosphere, or corona. Images from the first flight of Walker's solar telescope appeared on the cover of Science magazine on Sept. 30, 1988.

"Art Walker obtained the first soft X-ray images of the sun," recalled Bob Byer, chair of the Department of Applied Physics. "The images showed spectacular surface details of the sun, including flares, bubbles and gas jets. Art was just thrilled with these images. I will never forget his face when he showed us the first images."

Walker launched 14 telescopes in NASA's first Multi-Spectral Solar Telescope Array (MSSTA) flight in 1991 and 19 telescopes in the second flight. Since a telescope's flight filter only lets in one wavelength of light at a time -- and each wavelength represents a different temperature -- arrays of telescopes allow researchers to look at different temperatures throughout the sun and gain a greater understanding of solar activity. Walker's technique has since been used in NASA's Chandra X-ray Observatory, to study the nighttime sky, and in a worldwide chain of ground stations called the Global Oscillation Network Group (GONG), to study solar activity.

On Sept. 15, 2000, the departments of Physics and Applied Physics and the African and Afro-American Studies Program hosted a celebration to honor Walker's "innovative research and inspiring teaching in physics, particularly in solar physics, as well as his exemplary contributions to the black community at Stanford," said psychology Professor Ewart Thomas. At the celebration, NASA officials surprised Walker with a Distinguished Public Service Medal in recognition of four decades of distinguished scholarship, achievements in experimental space sciences and extensive service to NASA and the nation on many advisory and review boards.

Walker is survived by his wife, Victoria T. Walker, of Stanford; daughter Heather M. M. Walker of Los Altos Hills; stepsons Nigel D. Gibbs of Los Angeles and Eric D. Gibbs of Temecula; and four grandchildren. He was also beloved by many cousins, other relatives and friends, and members of the Sigma Pi Phi fraternity (Gamma Chi Boule), of which he was a member of long standing.

In lieu of flowers, donations may be sent to the A.B.C. Walker II Memorial Fund for the greater inclusion of ethnic minorities and women in the sciences. Checks should be made payable to Stanford University and sent to: Department of Physics, c/o Jenifer Conan-Tice, Stanford University, Stanford, CA 94305-4060.