Design Failure Lessons

Space Shuttle Challenger

• Initial hypotheses on cause of shuttle explosion
• Description of rocket boosters
• Initial theories on source of booster rocket failure
• Proper sequence of booster ignition
• Comparison of Risk Analysis Methods
• Most rigorous risk assessment available
• NASA's risk assessment
• Cold begins to be suspected as a factor 2/86
• Builder of rockets (Morton Thiokol) consulted regarding affect of cold
• No escape procedures during the first 2 min. of the flight
• Changes in booster design in 1983 increased stress on seals
• NASA warned about eroding seals
• Prior reports cited O ring damage
• Waiver granted (3/83) regarding backup seal on booster rockets
• Existing O-ring backup not functional
• Capability of secondary seal deteriorates as flight continues
• Thiokol engineers recommend lower temperature limit on launch
• Redesign initiated on rocket seams without "proof" that they failed on the Challenger 2/86
• Solutions to o-ring difficulties proposed in August, 1985
• Example of solution proposals

1. Broad, William J., "The Shuttle Inquiry: NASA Discusses Evidence; Investigators Examine Data for Possible Booster Flames," The New York Times, SECTION: Section A; Page 12, Column 1; National Desk, February 3, 1986
2. Diamond, Stuart, "The Shuttle Inquiry: Exploring Key Wreckage; NASA's Risk Assessment Isn't Most Rigorous Method," The New York Times, SECTION: Section A; Page 25, Column 1; National Desk, February 5, 1986
3. Boffey, Philip M., "NASA Was Worried by Cold's Effects, Commission Is Told," The New York Times, SECTION: Section A; Page 1, Column 6; National Desk, February 7, 1986
4. Boffey, Philip M., "Panel Asks NASA for Its Reports on Booster Risks," The New York Times, SECTION: Section A; Page 1, Column 6; National Desk, February 10, 1986
5. Boffey, Philip M., "NASA Set Aside a 'Fail-Safe' Rule for Booster Seal," The New York Times, SECTION: Section A; Page 1, Column 3; National Desk, February 13, 1986
6. Broad, William J., "New Designs under Study for Booster Rocket Seams," The New York Times, SECTION: Section 1; Page 8, Column 3; National Desk, February 15, 1986
7. Broad, William J., "Changes in Rocket Strained Booster's Seals, Experts Say," The New York Times, SECTION: Section A; Page 14, Column 1; National Desk, February 17, 1986
8. Sanger, David E., "Rocket Engineer Describes Arguing against Launching," The New York Times, SECTION: Section A; Page 1, Column 6; National Desk, February 19, 1986
9. The New York Times, "Major News; Shuttle Investigators Wonder Why Engineer's Warnings Went Unheeded," The New York Times, SECTION: Section 4; Page 1, Column 1; Week in Review Desk, February 23, 1986
10. Wilford, John Noble, "Shuttle Crash Where Clues Have Led So Far," The New York Times, SECTION: Section C; Page 1, Column 1; Science Desk, February 25, 1986
11. Sanger, David E., "Sifting Facts from Chaff," The New York Times, SECTION: Section 1; Page 11, Column 1; National Desk, March 8, 1986