X-15 Rocket Plane: Pilots Flew It So High They Were Officially Recognized as Astronauts

North American X-15 rocket-powered experimental aircraft was created in late 1950s to fly on the boundaries of space, providing the nascent U.S. aerospace agency, NASA, with crucial insights into the mechanics of spaceflight and the tolerances of human and aircraft performance. It was the most capable of a series of X-designated rocket aircraft, such as Bell’s X-1 and X-2. Just like them, it was launched into the stratosphere from a mothership (a modified B-52 Stratofortress), upon which its rocket motors ignited, accelerating the aircraft to several times the speed of sound.