Joseph Percival Allen IV, born 27 June 1937 in Crawfordsville, Indiana, is an American physicist and astronaut. A Yale physics PhD (1965), he was a research associate in the nuclear physics laboratory at the University of Washington when NASA selected him in 1967 in its sixth, scientist-astronaut group. As a mission specialist he flew aboard the Space Shuttle Columbia on STS-5 (November 1982), the program's first fully operational flight, and then on STS-51A (November 1984), during which he helped retrieve two satellites from orbit, logging 314 hours in space. After leaving NASA in 1985, he led Space Industries International and chaired Veridian Corporation until 2004. Aller-retour pour l'espace (1984), co-written with Russell Martin, is his photographic account of the experience of spaceflight.