After graduating from Test Pilot School and the Aerospace Research Pilots School, he was assigned as an instructor teaching control systems to future astronauts and flying the F-101, F-104, F-106, T-38, and T-33 aircraft.
Became a member of the support crew for Apollo 10, was CAPCOM for the Apollo 11 mission, and served on the backup crew for Apollo 13.
Served as Lunar Module Pilot for Apollo 16 becoming the 10th (and youngest) man to set foot on the moon. In total, Duke was involved with 5 of the 9 missions to the moon.
Aided in the early design of the Space Shuttle cockpit and the Shuttle operations planning.