> It is probably true that the design was somewhat more unacceptably risky at 29 F. But that was a relatively minor point
This was a critical part of the danger:
> Temperature Effects
> The record of the ... meetings ... on January 27th, the night before the launch of flight 51-L, shows ... limited consideration was given to the past history of O-ring damage in terms of temperature. The managers compared as a function of temperature the flights for which thermal distress of O-rings had been observed--not the frequency of occurrence based on all flights (Figure 6).
> In such a comparison, there is nothing irregular in the distribution of O-ring "distress" ... between 53 degrees Fahrenheit and 75 degrees Fahrenheit. When the entire history of flight experience is considered, including "normal" flights with no erosion or blow-by, the comparison is substantially different (Figure 7).
> This comparison of flight history indicates that only three incidents of O-ring thermal distress occurred out of twenty flights with O-ring temperatures at 66 degrees Fahrenheit or above, whereas, all four flights with O-ring temperatures at 63 degrees Fahrenheit or below experienced O-ring thermal distress.
> Consideration of the entire launch temperature history indicates that the probability of O-ring distress is increased to almost a certainty if the temperature of the joint is less than 65.
For completeness: the engineers' rebuttal: https://people.rit.edu/wlrgsh/FINRobison.pdf but I don't think the back-and-forth takes away from the larger point that there are more- and less-effective ways to visually convey data
This was a critical part of the danger:
> Temperature Effects
> The record of the ... meetings ... on January 27th, the night before the launch of flight 51-L, shows ... limited consideration was given to the past history of O-ring damage in terms of temperature. The managers compared as a function of temperature the flights for which thermal distress of O-rings had been observed--not the frequency of occurrence based on all flights (Figure 6).
> In such a comparison, there is nothing irregular in the distribution of O-ring "distress" ... between 53 degrees Fahrenheit and 75 degrees Fahrenheit. When the entire history of flight experience is considered, including "normal" flights with no erosion or blow-by, the comparison is substantially different (Figure 7).
> This comparison of flight history indicates that only three incidents of O-ring thermal distress occurred out of twenty flights with O-ring temperatures at 66 degrees Fahrenheit or above, whereas, all four flights with O-ring temperatures at 63 degrees Fahrenheit or below experienced O-ring thermal distress.
> Consideration of the entire launch temperature history indicates that the probability of O-ring distress is increased to almost a certainty if the temperature of the joint is less than 65.
https://www.nasa.gov/history/rogersrep/v1ch6.htm#:~:text=Thi...
---
In fact it is also a case study in data visualization: https://williamwolff.org/wp-content/uploads/2013/01/tufte-ch... (more briefly: https://www.residentmar.io/2016/02/07/space-shuttle-challeng...)
For completeness: the engineers' rebuttal: https://people.rit.edu/wlrgsh/FINRobison.pdf but I don't think the back-and-forth takes away from the larger point that there are more- and less-effective ways to visually convey data