I am only a retired English teacher with no mechanical abilities at all, so I have to ask... why couldn’t they just replace the O-rings when they saw that they were getting damaged?
Hind sight is 20/20, but I wonder why they didn’t start working on a redesign of the O-rings sooner if they knew in advance there was a problem. I know those guys felt terrible about it. It was a tragic management decision.
The problem wasn't just the o-rings as such ... the o-ring channels and the way the segments locked together wasn't strong enough. The segments flexed too much with respect to each other, which compromised the o-ring ability to seal the gap ... this was exacerbated by the cold. They did fly with fresh o-rings each time.
The two years between Challenger explosion and the next flight was taken to completely redesign the way the segments connected to each other ... and to build a bunch of new segments.
It was a much, much more complex issue than just “get a new O-ring.” The whole joint and O-ring design was redone, and this is not just a Shark Bite plumbing joint O-ring on a piece of copper or PEX. This was a very complex, very large, custom engineered O-ring. I’ve never read the Rogers Commission report, but renowned and very interesting Manhattan Project Physicist Richard Feynman was on the commission. He was quite a good communicator, wrote some very interesting books. It’s quite likely the commission report might be understandable to a layperson non-engineer like yourself because of his involvement, if you wanted to dig into this issue.
You have tumbled on to the fatal flaw in the entire pentagon acquisition managerialism coupled with a "manager lead" [e.g. Harvard Business School finance types] military industrial complex. The first rocket design should have been considered a testing prototype, and should only have gone into final design and production after thorough cycles of testing to work out the bugs, flaws, and errors. That's why Musk is successful. And that is why the Challenger crashed.
You cannot override the laws of physics through "management" decision making devoid of engineering input. But they did. And they do today. And it takes too long, costs a bundle and is inherently flawed. And that is why all the angst in Defense procurement and among the so-called prime contractors. Like everything else in government it is populated mostly by process people who protect their useless jobs. NASA is just as bad.
The O-Rings weren’t originally damaged on that failed flight. The material of the O-Ring couldn’t flex properly in the cold weather. This failure to flex properly created a gap that allowed the combustion to get outside the rocket and destroy the shuttle.
> why couldn’t they just replace the O-rings when they saw that they were getting damaged?
The organization ( NASA + Thiokol ) needed to acknowledge the problem to address it, but instead stubbornly resisted escalation. There were probably dozens of issues of different severity, but at some layer of management they all became anecdotally equivalent, so the critical issues became lost in the noise. As long as the rockets succeeded Thiokol management and NASA felt the issues were demonstrably low risk and indulged in an orgy of mutual self-congratulation.
During the Rogers Commission, Feynman toured the facility where they assembled the SRBs, and he pointed out critical flaws in the inspection process that could allowed for other similar failures from a different root cause. Notably the Rogers Commission report downplayed it as irrelevant, omitted significant information, and Feynman had to write his own report which became an appendix and ultimately the conclusions of the report. He demonstrated the critical fault explicitly and unequivocally on live TV at a Congressional hearing, at the same time the political elements of the commission were trying to whitewash the whole affair to protect insiders. The allowed the dissenting minority in the commission to force a revision of the final report and recommendations.
Interestingly ASME and other engineering organizations have incorporated the lessons of Challenger in standards and practices (e.g GD&T), but also made it a form of arcane knowledge served only to insiders (the ASME manual is behind a paywall). Eventually FMEA and Risk analysis in engineering benefited enough so the information escaped and became widely incorporated. For example I used it in 2008-2016 to engineer reliable backend systems for e-commerce. It was interesting to trace the source of some of the engineering practices I learned about back to the Challenger accident report. I used the risk assessment heuristics for years before I discovered the origins in FMEA (Failure Mode and Effects Analysis) and the references to that knowledge came to me indirectly through people quoting the Feynman Report.
Feynman had a great little quip which made it into the final report:
“For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.”
This echos Galileo’s letter to the Grand Duchess Christina of Tuscany in 1615 (translated):
“It is not within the power of practitioners of demonstrative sciences to change opinion at will, choosing now this and now that one; there is a great difference between giving orders to a mathematician or a philosopher and giving them to a merchant or a lawyer; and demonstrated conclusions about natural and celestial phenomena cannot be changed with the same ease as opinions about what is or
is not legitimate in a contract, in a rental, or in commerce.”
That is exactly what the engineers wanted to do. That involves taking the booster apart, removing the damaged seals, and then waiting for replacements. The management at that time did not want to tarnish their productivity records; and, felt that the expense of parts, labor, times, and money outweighed the safety of the flight.
Hey, with regards to the o-rings, they actually did replace the rubber fillings after every flight. So, it wasn’t wear and tear with o-rings being used over and over that caused the tragedy. It was the fact that it was so cold and the o-rings were so brittle that they didn’t expand and seal the joints properly on ignition of the Solid Rocket Boosters at liftoff.
I worked in the Shuttle program from 1998 to 2003. Arrived in January of 1998, two years after Challenger and a few months before the first Shuttle flight after the program was halted.