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What about using similar techniques on other problematic parts which did not have disastrous failures? If you had used the same reasoning and analysis, how many

by nickff 10y ago

What about using similar techniques on other problematic parts which did not have disastrous failures? If you had used the same reasoning and analysis, how many flights (which ended up successful) would have been delayed or cancelled? Are you not falling victim to a sort of survivor-ship bias in only applying these analyses to 'failed' missions? It seems obvious in hindsight that the 'whistle-blowers' were right, but how many people voiced concerns which turned out to be erroneous?

nemild 10y ago
While the graphs I highlight don't show it, the broader paper uses both actual launch data AND experimental data to derive the regression. This experimental data presumably should be available regardless of if this reasoning had been used earlier on launch data. This is one good reason why experimental data is so critical, as real world data can be biased. You're absolutely right though about this being "Monday morning quarterbacking" with any analysis after the events. That said, two things are clear: 1. The most knowledgeable engineers were strongly against launch (see Ebeling and Boisjoly at Morton Thiokol) 2. There were huge statistical flaws made by decision makers at NASA before launch (see Feynman as noted in this thread)
byoung2 10y ago
The entire shuttle program was plagued by a pattern of ignoring safety objections. It was widely known ahead of disasters that the whistle-blowers were right about many issues, but were ignored. I made this point in another HN thread about Challenger, but if you drive drunk on a regular basis, it is not safe and it is only a matter of time before you crash and kill a family of four. The fact that you have driven drunk for 20 years and haven't killed anyone yet doesn't change the fact that driving drunk was dangerous. Evidence of this phenomenon in the shuttle program was that foam shedding (insulation for the main fuel tank falling off during launch) was observed as early as 1983, and had been noted as a substantial risk many times over the years. Engineers pressed for high resolution images to inspect damage, but those requests were denied. NASA continued to "drive drunk" over the years, even after Challenger, and inevitably, disaster struck when Columbia was damaged by a piece of foam that broke off during launch, resulting in disintegration during reentry.[1] After grounding the fleet and improving safety, the very next launch suffered similar foam shedding, though from a different part of the tank. The launch after that was also pressed, after delays and objections from the chief engineer and safety officer. 1. https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaster https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...

by nickff 10y ago

nemild 10y ago

While the graphs I highlight don't show it, the broader paper uses both actual launch data AND experimental data to derive the regression. This experimental data presumably should be available regardless of if this reasoning had been used earlier on launch data. This is one good reason why experimental data is so critical, as real world data can be biased. You're absolutely right though about this being "Monday morning quarterbacking" with any analysis after the events. That said, two things are clear: 1. The most knowledgeable engineers were strongly against launch (see Ebeling and Boisjoly at Morton Thiokol) 2. There were huge statistical flaws made by decision makers at NASA before launch (see Feynman as noted in this thread)

byoung2 10y ago

The entire shuttle program was plagued by a pattern of ignoring safety objections. It was widely known ahead of disasters that the whistle-blowers were right about many issues, but were ignored. I made this point in another HN thread about Challenger, but if you drive drunk on a regular basis, it is not safe and it is only a matter of time before you crash and kill a family of four. The fact that you have driven drunk for 20 years and haven't killed anyone yet doesn't change the fact that driving drunk was dangerous. Evidence of this phenomenon in the shuttle program was that foam shedding (insulation for the main fuel tank falling off during launch) was observed as early as 1983, and had been noted as a substantial risk many times over the years. Engineers pressed for high resolution images to inspect damage, but those requests were denied. NASA continued to "drive drunk" over the years, even after Challenger, and inevitably, disaster struck when Columbia was damaged by a piece of foam that broke off during launch, resulting in disintegration during reentry.[1] After grounding the fleet and improving safety, the very next launch suffered similar foam shedding, though from a different part of the tank. The launch after that was also pressed, after delays and objections from the chief engineer and safety officer. 1. https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaster https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...