For the Digital Fly-By-Wire project, NASA technicians replaced cables and push rods in this F-8 Crusader with an electronic flight-control system coupled to a digital computer. The computer interpreted the pilot's control inputs and transmitted them to electric motors to actuate the aerodynamic control surfaces. Fly-by-wire is lighter, more precise in its ability to deliver flight-control commands, and more efficient than the control systems it replaced. It uses multiple wired paths through which flight-control commands are sent to control surfaces, providing redundancy in the event of damage. The first phase of the program used the same type of guidance computer NASA astronauts used to reach the moon in the 1960s, with just 38K of memory, 36K of which was read-only. In the second phase, the F-8 was used to validate flight-control computers later used on the space shuttles. The last F-8 DFBW flight took place on April 2, 1985.