“What went wrong: An O-ring failure in a solid rocket booster led to leaking of hot gases against the external tank. The resulting explosion killed the seven member crew.
NASA was frenetic over publicizing the teacher in space angle, even to the extent of compromising mission safety. When the launch was delayed, meaning the flight day McAuliffe was to teach her ‘lesson from space’ was moved from a weekday to a weekend, NASA took the unprecedented move of ordering the flight schedule to be rearranged so the lesson would instead be given on a school day. The training and planning of months had to be revised in hours. Payload specialist Jarvis was on this flight only because his original crew assignment had been deleted when Congressman Bill Nelson claimed a seat on the flight. Jarvis, an employee of Hughes, was supposed to be making observations of satellite deployment. But since there was no Hughes satellite aboard Challenger, the assignment made no sense. Exploded 73 seconds after launch, all seven crewmembers were killed and the TDRSS satellite aboard was destroyed. The crew cabin remained intact after the shuttle Challenger disintegrated. Indications that emergency oxygen supplies were manually activated showed that some crew members may have remained alive until the cabin hit the ocean.”