Seventy three seconds after take off, the Challenger Space Shuttle encounters an unexpected disaster. Find out more in this clip from I Was There. | HISTORY

The NASA space shuttle Challenger exploded 40 years ago, on January 28, 1986, just 73 seconds after liftoff. The disaster claimed the lives of all seven astronauts aboard, including Christa McAuliffe, a teacher from New Hampshire who would have been the first civilian in space. “The crew of the space shuttle Challenger honored us by the manner in which they lived their lives,” President Regan said in an address to the nation that night. “We will never forget them, nor the last time we saw them,

On January 28th, 1986 the Space Shuttle Challenger exploded and broke apart on take off. This week, Destruction Decoded explores the top 10 most dramatic space accidents, from Baikonur to Cape Canaveral. Watch Destruction Decoded on Wednesdays at 8pm, on National Geographic UK. | National Geographic UK