[[Image:Space Shuttle Challenger Crew.jpg|thumb|right|300px|The Space Shuttle Challenger crewmembers are: in the back row from left to right: Mission Specialist, Ellison S. Onizuka, Teacher in Space Participant Sharon Christa McAuliffe, Payload Specialist, Greg Jarvis and Mission Specialist, Judy Resnik. In the front row from left to right: Pilot Mike Smith, Commander, Dick Scobee and Mission Specialist, Ron McNair.]]
The '''Space Shuttle Challenger''' disintegrated due to O-ring failure 73 seconds after lift-off on January 28, 1986, killing all seven members on board. Those killed included the first private citizen to fly on a [[space shuttle]], who was a high school teacher. <ref>http://www.fas.org/spp/51L.html</ref>
President [[Ronald Reagan]] mourned the tragedy in an address to the [[United States of America|nation]]:
NASA had said the O-rings had a safety factor of 3, which [[Richard Feynman]] later exposed as untrue.
* [[SRB]] engineers had previously warned about problems in the o-rings, but had been dismissed by NASA management.<ref> [http://duartes.org/gustavo/blog/post/richard-feynman-challenger-disaster-software-engineering Richard Feynman, the Challenger Disaster, and Software Engineering]</ref>
* For example. in determining if flight 51-L was safe to fly in the face of ring erosion in flight 51-C, it was noted that the erosion depth was only one-third of the radius. It had been noted in an experiment cutting the ring that cutting it as deep as one radius was necessary before the ring failed. Instead of being very concerned that variations of poorly understood conditions might reasonably create a deeper erosion this time, it was asserted, there was "a safety factor of three." This is a strange use of the engineer's term, "[[safety factor]]."<ref> [http://www.ralentz.com/old/space/feynman-report.html Feynman's Appendix to the Rogers Commission Report on the Space Shuttle Challenger Accident]</ref>
==References==