On 28 January 1986, the Challenger space shuttle exploded 73 seconds into its mission, leaving no survivors. But was the disaster an avoidable one? In an in-depth examination of the events leading up to what was then the worst catastrophe in American space-flight history, a group of engineers are revealed to have attempted to persuade Nasa to postpone the lift-off, fearing the sudden freezing of temperatures in Florida would jeopardise the vehicle.