Seven American spacefarers were killed in a tragic event 40 years ago today that has become widely known as the Challenger disaster.

Lost that fateful day were Commander Francis Richard Scobee, pilot Michael Smith, mission specialists Judith Resnik, Ronald McNair and Ellison Onizuka, payload specialist Gregory Bruce Jarvis, and teacher-in-space Christa McAuliffe, who was flying as part of a Science, Technology, Engineering and Mathematics outreach program.

NASA's Space Shuttle Program, which ran from 1981 to 2011, was a complex and ambitious project that pushed the boundaries of space exploration, but was marred by two tragic accidents during the shuttle era.

Space Shuttle Discovery remains intact at the Smithsonian after officials warned relocation could damage the historic orbiter.