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On 28 January 1986 the Challenger space shuttle exploded just 73 seconds after being launched from Cape Canaveral in Florida.

All seven crew members were killed and the disaster was blamed on a faulty seal.

Millions of schoolchildren were watching the launch live because a teacher called Christa McAuliffe was on board as part of Nasa's Teachers in Space initiative.

The technology journalist Michael Grothaus was nine at the time and says: "I remember looking at my teacher and she had a look of disbelief on her face. She flipped the channel and ran into the hallway."

This clip is from 5 live Daily on 5 February 2015.