In this historical photo from the U.S. space agency, a technician mounts a model of the Apollo Launch Escape System (LES) in the Unitary Wind Tunnel at the NASA Ames Research Center, Moffett Field, California. The LES was a tower like structure consisting of four solid propellent motors mounted atop the Apollo Command Module.
In the event of a contingency, (booster failure or some other imminent failure) the LES would be commanded to ignite, subsequently removing the Command Module from the Saturn launch vehicle.
Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).