The Space Shuttle Challenger was hurtling through the air at twice the speed of sound when pilot Michael Smith noticed something alarming.
Sitting on the right side of the flight deck, Smith looked out his window and likely saw a flash of vapor or a fire.
“Uh oh,” he said.
Down on the ground at Mission Control, a computer screen indicated falling pressure in the right booster rocket. It was leaking fuel.
As was later learned, the cold of the Florida morning had stiffened the rubber O-rings that held the booster sections together, containing the explosive fuel inside. The rings failed to expand fully in the cold, leaving a gap of less than a millimeter between booster sections.
