The Challenger Disaster

Risk Management

Risk Management

The art and science of identifying, analyzing, and responding to risk

The Challenger Mission 51L

• • • 10 th mission for the Challenger Shuttle TISP – Teachers In Space Program – Christa McAuliffe Politically Charged Launch – Christa was to appear via television link during Reagan’s State of the Union Address in 1986

Challenger Delays

• • • • • • • Liftoff Initially Scheduled for 15:43 EST on Jan. 22, 1986 Delays in 61-C mission pushed liftoff to Jan. 23, then Jan. 24 Reset to Jan. 25 due to weather Postponed another day due to launch processing problems Rescheduled for 9:37 EST Jan. 27 due to weather Delayed again due to equipment failure for 24 hours Final 2 hour delay due to hardware interface module problems Liftoff: 11:38 EST January 28, 1986

The Challenger Disaster

73 Seconds After Liftoff

What Went Wrong??

• • Failure of an “O-ring” seal in the solid-fuel rocket on the Space Shuttle Challenger's right side Flames cut into main liquid fuel tank

Four Main Causes of O-Ring Failure

• • • • Pre-flight Leak Tests O-Ring Erosions Joint Rotation Low Temperatures

Poor Risk Management

• • Risks were managed using Critical Items Lists – – Criticality 1-Loss of Life or Ship Criticality 2-Mission Aborted CIL Flaws – Unreliable • In previous missions, criticality1 issues occurred but loss of life/ship did not – Negotiable • Identified risks could later be waived

Known Potential Problems

• • O-rings were “Criticality 1” feature O-ring seal failure on previous missions – Launch Constraint placed on subsequent launches • These constraints had been imposed and regularly waived by the SRB Project Manager

Known Potential Problems

• • • Very low ambient temperatures recognized as concern by Tiokol – O-ring performance at this temperature not understood NASA officials pressured Tiokol to withdraw its concerns Upper officials at NASA were unaware of these discussions and ignorantly approved launch

References

• • • • • “Space Shuttle Challenger 1986” ( http://www.jlhs.nhusd.k12.ca.us/Classes/Social_Science/Challenger.h

tml/Challenger.html

), (1996) “Space Shuttle Challenger Disaster-A NASA Tragedy” ( http://space.about.com/cs/challenger/a/challenger.htm

) “Expert Panel Recommends Improvements for Space Shuttle Safety Program”, ( http://www4.nationalacademies.org/news.nsf/isbn/NI000494?OpenDo

cument ), (March 3, 1988) “An Accident Rooted In History” ( http://spacelink.nasa.gov/NASA.Projects/Human.Exploration.and/De velopment.of.Space/Human.Space.Flight/Shuttle/Shuttle.Missions/Flig ht.025.STS-51-L/An.Accident.Rooted.in.History

), (June 6, 1986) “The Challenger Accident” ( http://www.me.utexas.edu/~uer/challenger/chall2.html#mechflaw ), (1997)