Challenger Space Shuttle

995 views
728 views

Published on

Key visualizations of the decision to launch the Space Shuttle Challenger on 27 January 1986. Includes animation of the mechanical failure and data analysis.

Published in: Technology
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
995
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
24
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Challenger Space Shuttle

  1. 1. © Anthony Cutler Limited 2002-2013 public 1.0 The decision to launch Space Shuttle Challenger – 27 January 1986 Unanticipated knowledge Anthony Cutler’s blog on operational excellence and risk management www.anthonycutler.com
  2. 2. © Anthony Cutler Limited 2002-2013 public 1.0 2 On 27 January 1986, NASA engineers held a conference to decide whether the next day’s launch should proceed The joints, where the stages of the Solid Fuel Rocket Booster (SFRB) were mated, featured two quarter inch (5mm) rubber o-rings – around 14 feet (3m) in diameter. When the fuel was ignited, stress was developed in the structure tending to make the joint “rotate”. The joint-sealing putty was often dislodged during take off, allowing fuel as far as the first O-ring. Two O-rings were provided as there were doubts about joint integrity and some redundancy was thought prudent. During this brief interval of ignition (fractions of a second), it was important that the rubber in the O-rings maintained the seal. There were concerns that at low temperatures, the rubber hardened making its response slower and failing to seal for a critical few milliseconds. Space Shuttle Challenger
  3. 3. © Anthony Cutler Limited 2002-2013 public 1.0 3 Engineers observed “blow-by” where burning fuel had clearly escaped the primary O-ring on a number of recovered units. “Blow-by” of fuel past the primary O-ring had been observed on 7 of the 24 space-shuttle flights. Doubts had arisen about the ability of rubber O-rings to seal in rocket fuel at low temperatures The forecast temperature for the next day’s launch was 31 F. For more background see: Vaughan, D (1996) The Challenger Launch Decision, Chicago University Press Space Shuttle Challenger
  4. 4. © Anthony Cutler Limited 2002-2013 public 1.0 4 pin Zinc-chromate putty 1/4” Viton o-rings Rocket fuel Space Shuttle Challenger
  5. 5. © Anthony Cutler Limited 2002-2013 public 1.0 5 Rocket fuel Space Shuttle Challenger Escaping rocket fuel
  6. 6. © Anthony Cutler Limited 2002-2013 public 1.0 6 O-rings were known to harden at low temperatures and to seal more slowly There was a suspicion from data that there were more incidents at low temperatures Actual data suggests a temperature effect. When this data was presented to NASA engineers at the eve-of-launch conference, all the zeros (incident-free launches) were omitted and only the flights were there had been an incident featured. NASA engineers were sceptical of any evidence (signal) that temperature had an effect on risk of “blow-by”. Space Shuttle Challenger
  7. 7. © Anthony Cutler Limited 2002-2013 public 1.0 7 80706050 3 2 1 0 Joint temp (deg F) numberofincidents Incidents on "blow-by" on shuttle flights Data as presented to NASA engineers
  8. 8. © Anthony Cutler Limited 2002-2013 public 1.0 8 80706050 3 2 1 0 Joint temp (deg F) numberofincidents Incidents on "blow-by" on shuttle flights Full picture of data
  9. 9. © Anthony Cutler Limited 2002-2013 public 1.0 9 However, when the data is presented in full with the events where there were no “blow-by”s, there is a strong feeling that the problem- free launches only occurred at higher temperatures. The way the data is presented has a strong effect on its interpretation. Space Shuttle Challenger

×