Born on 24 August 1936 in Cleveland, Ohio, Arthur B. C. Walker Jr was a solar physicist who specialized in the development of extreme-UV optics. After earning his PhD in physics from the University of Illinois in 1962, Walker served three years in the US Air Force and then worked for nine years at Aerospace Corporation. In 1974 he joined the faculty of Stanford University, where he would remain for the rest of his career. At Stanford, Walker held joint professorships in both applied physics and physics, was a member of the Hansen Experimental Physics Laboratory and the Center for Space Science and Astrophysics, and served for four years as associate dean of graduate studies. Over his career he developed space-borne instruments that researchers used to study the solar corona and other astrophysical phenomena at x-ray and extreme-UV wavelengths. Walker also devoted considerable time to mentoring minority and women graduate students, including Sally Ride, the first American woman to go to space. He served on numerous committees at Stanford, NASA, NSF, and the National Academy of Sciences, and was selected by President Ronald Reagan to serve on the commission that investigated the 1986 space shuttle Challenger explosion. Walker remained active in research until his death from cancer at age 64 in 2001. Technology that he developed was adopted for use on spacecraft including the Chandra X-Ray Observatory. (Photo credit: NASA, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection)
