John P. Hagen was a solar radio astronomer who earned an M.A. from Wesleyan in 1931 and began working for the Naval Research Laboratory in 1935. There he worked on improving radar techniques and helped develop an automatic ground speed indicator for aircraft. After World War II he headed NRL's radio physics research group, which developed the world's most precise radio telescope in 1950, a year after he earned a Ph.D. in astronomy at Georgetown. In 1955 he became director of the Vanguard earth satellite program and, when that program became part of NASA on 1 October 1958, he remained chief of the NASA Vanguard division. In 1962, he returned to higher education, becoming a professor of astronomy at Pennsylvania State University.