NASA (the National Aeronautics and Space Administration) is best known for its space missions but is also a world pioneer in more conventional aviation. For example, NASA and the Air Force worked together to create the X-15 rocket plane that still holds the world record for the fastest-piloted aircraft ever flown (Mach 6.7). NASA operates a fleet of aircraft that help conduct its aeronautical research, train astronauts, study the planets, and operate the agency’s many air and space programs. NASA operates everything from private jets to specialized experimental aircraft, pushing the limits of aviation.