What happened in the Challenger disaster - 13 Minutes Presents: The Space Shuttle, BBC World Service

Key Concepts:

• Space Shuttle Challenger Disaster (January 28, 1986)
• Solid Rocket Boosters (SRBs)
• O-Rings (primary and secondary)
• Morton-Thiokol (NASA contractor responsible for SRBs)
• Blow-by (hot gases flowing past O-rings)
• Rogers Commission (Presidential commission to investigate the disaster)
• Normalization of Deviance
• Launch Commit Criteria (LCC)
• Teleconference (Thiokol engineers and NASA)
• Management vs. Engineering Perspective

1. The O-Ring Concern and Initial Recommendation Against Launch

• Background: The episode focuses on the events leading up to the Challenger disaster, specifically the concerns raised by engineers at Morton-Thiokol regarding the effect of cold temperatures on the O-rings sealing the joints of the solid rocket boosters (SRBs).
• Temperature Threshold: The NASA person called Bob Ebeling and said the temperatures are going to be as low as 27 or 29 degrees overnight.
• Ebeling's and Russell's Concerns: Engineer Bob Ebeling and junior engineer Brian Russell expressed concerns about the O-rings' ability to seal properly in freezing temperatures. Ebeling told his daughter, Leslie Ebeling-Serna, "We've got to stop this launch... We're gonna have a catastrophic disaster."
• Task Force Recommendation: The O-ring task force, including Russell, Ebeling, and Roger Boisjoly, recommended against launching at the scheduled temperature. They understood the significance of this recommendation, as it was unusual to advise against a launch.

2. Data Gathering and the Teleconference

• Data Collection: The Thiokol engineers gathered data, charts, and temperature tests to justify their recommendation.
• Teleconference Setup: A teleconference was held the evening before the launch between Thiokol engineers in Utah and NASA groups at Marshall Spaceflight Center in Alabama and Kennedy Space Center in Florida.
• Presentation Content: The presentation included a history of flights with joint issues, temperature tests of the O-rings, and data on blow-by (hot gases flowing past the O-rings).
• STS-51-C: Boisjoly presented data from STS-51-C, the coldest launch to date (53 degrees Fahrenheit), where significant blow-by was observed. He expressed "absolute amazement that we had not had a disaster at that point in time."
• Conflicting Data: NASA personnel were confused because the two worst cases of O-ring damage happened at vastly different temperatures.

3. NASA's Challenge and Thiokol Management's Shift

• Mulloy's Disagreement: Larry Mulloy from Marshall Space Flight Center challenged the Thiokol engineers' recommendation, arguing that temperature was independent of O-ring blow-by and erosion. He questioned, "My God, Thiokol, when do you want me to launch, next April?"
• Hardy's Appallment: George Hardy, Associate Director at Marshall Spaceflight Center, expressed being "appalled" at the Thiokol recommendation.
• Offline Meeting (Caucus): Joe Kilminster, a Thiokol Vice President, called for a five-minute offline meeting to reconsider the situation.
• Mason's Influence: During the caucus, General Manager Jerry Mason told Bob Lund, the Vice President of Engineering, to "take off your engineering hat and put on your management hat." Mason wanted to take a poll of only the vice presidents.
• Lund's Decision: Bob Lund, under pressure from management and NASA, ultimately agreed to support the launch.

4. The Final Decision and Immediate Aftermath

• Thiokol's Revised Recommendation: Joe Kilminster informed NASA that Thiokol supported the launch. Allan McDonald, a Thiokol manager at Kennedy Space Center, refused to sign the written recommendation, so Kilminster signed it instead.
• Russell and Boisjoly's Realization: After the call, Brian Russell and Roger Boisjoly realized that the burden of proof had been shifted, requiring them to prove it was unsafe to fly instead of proving it was safe.
• Ebeling's Premonition: On the morning of the launch, Bob Ebeling expressed his deep concern to his daughter, stating, "This is going to be a horrible way for me to end my career... we're gonna have a catastrophic event. He said, I stake my life on it."
• The Disaster: The Challenger exploded 73 seconds into the ascent.
• Immediate Reaction: Brian Russell knew immediately that it was "our problem."

5. The Technical Cause and the Rogers Commission

• Technical Explanation: The disaster was caused by the failure of the O-rings to seal properly in the cold temperatures. Hot gases escaped, leading to the failure of a strut and the subsequent breakup of the shuttle.
• Rogers Commission: President Reagan established the Rogers Commission to investigate the disaster. The commission included notable figures like Neil Armstrong, Richard Feynman, and Sally Ride.
• Commission Findings: The Rogers Commission concluded that the Challenger disaster was "an accident rooted in history," criticizing NASA's decision-making, communication, management structure, and organizational culture.

6. Cultural and Systemic Failures

• Normalization of Deviance: Mike Mullane described the "normalization of deviance," where repeated instances of O-ring anomalies (like burned O-rings) were gradually accepted as normal.
• Communication Breakdown: Decisions made were not communicated up the chain of command.
• Management Pressure: NASA management pressured Morton-Thiokol to accept the launch despite the engineers' concerns.
• Preventable Disaster: The disaster could have been prevented at multiple points along the way.

7. NASA's Response and Lessons Learned

• Fletcher's Promise: NASA Administrator James Fletcher promised to strengthen management, improve engineering and design processes, and enhance internal communications.
• Historical Event: The Challenger disaster became a historical event, highlighting the importance of learning from mistakes to prevent future tragedies.

Conclusion:

The Challenger disaster was not simply a technical failure but a result of flawed decision-making processes, organizational culture, and communication breakdowns. The pressure to launch, combined with the normalization of deviance and the suppression of engineering concerns, created a perfect storm that led to the tragic loss of seven astronauts. The Rogers Commission's report and NASA's subsequent reforms aimed to address these systemic issues and prevent similar disasters in the future.