Colonel Shaun Geoffrey Christopher was the son of US Air Force Captain John Christopher and the leader of the first Earth-Saturn probe. He was accompanied on this mission by the astronauts Fontana and O'Herlihy.
In 1969, the USS Enterprise, which had accidentally traveled back in time from the year 2267, took aboard Captain John Christopher when he attempted to intercept the Enterprise with his F-104 Starfighter. Initially believing that returning Christopher to Earth would be impossible due to the fact that he might inadvertently change history with his new-found knowledge of the future, Commander Spock eventually realized that he had to be returned, or Shaun Geoffrey Christopher would never be born and the Saturn mission would never take place. (TOS: "Tomorrow is Yesterday"; ENT: "First Flight")
The exact date of his mission and the space agency is unknown; however, the time frame seems to indicate that NASA might be the likely host. Christopher was born sometime after 1969, the year his father was captured by the USS Enterprise.
In the short story "Assignment: One" of Strange New Worlds 8, Gary Seven is assigned to prevent Christopher from boarding one of the airplanes that would be involved in the September 11th terrorist attack.
The novelization of the episode "Relics" gives the name of the shuttle "loaned" to Montgomery Scott as the Christopher, named for Shaun Geoffrey Christopher, however in the episode, the name Goddard is legible on the hull.
Shaun also plays a minor part in Greg Cox's Eugenics Wars novels as he was meant to be the pilot of the first DY-100 sleeper ship initially scheduled to go to Saturn.
Commander Shaun Christopher is the main character of the Star Trek: Live stage show produced by Mad Science Productions and performed at various locations from 2010–2011, including Kennedy Space Center Visitor Complex.