Space shuttle prototype

In 1977, the space shuttle prototype Enterprise made its first free flights, in Earth's atmosphere, after separating from the 747 that carried it aloft. Writes NASA, not too melodramatically, in a short essay on test pilots: "When it came to launch the never-before-flown space shuttle from the back of a 747, nerves of steel were required yet again. When the Enterprise lifted off a 747 in 1977, no one knew for sure if it would clear the carrier aircraft's tail. Two pilots aboard the fledgling spaceship and two on the 747 put their lives on the line to find out."

Being a test pilot is an inherently very risky business. Some were badly burned in crashes, and others died in the line of duty, including NACA's Howard Lilly, whose D-558-1 jet-powered research airplane crashed on take-off in 1948, and X-2 pilot Jean Ziegler, who perished in 1953 (along with mothership crew member Frank Wolko) in an explosion during a captive flight under a B-50.