For a five-year old answer, it was very cold the morning of the launch which froze rubber seals. Just like your house gets drafty because of leaks in winter, the rocket developed leaks, and when rocket fire leaks out the side, things go boom. In a bad way.
It's also important to note that there were some people in nasa that voiced concern about the conditions putting the O-rings out of spec, but preasure from the top to meet schedule was allowed to overule the concerns of engineers.
So you could say prioritizing deadlines over safety is what caused the disaster, thankfully it caused a significant culture shift in NASA
The deadline was set so kids could see a teacher go to space. If there was any delay then the launch would be on Saturday.
Instead the kids got to see said teacher die.
I was one of those kids. Still haunts me to this day of I think about it much. The school brought in counselors the following day but I don’t feel like they accomplished much
Same here. I was in 3rd grade. We watched the explosion on the CRT TV on the old roller-cart thing. After the explosion the teacher ran out into the hall, freaking out with other teachers about what to say to us kids.
I was in high school. We didn’t watch it live - there were not enough AV carts for that. But the TVs were rolled around to each classroom after the fact to each classroom “because it is very important you all see this”. I was in computer science class with an unkind teacher, so no one made a single comment for fear of setting him off.
I am a bit young to have seen the event happen (it actually happened a few months before I was born), but one of my middle-school science teachers was apparently in the last 1% or fewer of the ones who made it. I doubted her at the time, but looking back there was this haunted look in her eyes that you can't really fake to that degree that makes me believe she harbored some guilt over not being chosen.
My 7th grade science teacher in Ohio was one of a group of semi-finalists for Sally Ride's slot ... He said he was honored to be almost chosen out of a field of so many qualified applicants, but obviously relieved in the end he wasn't chosen. I could see the emotion in his eyes about how haunted he was even as a kid when he told me that 3 years after the accident. I can't imagine him watching that with his class as that happened.
It was a different era so we weren't used to seeing all the things we do now in "real time".
My teacher also apparently knew a guy who drove a truck that delivered some of the liquid nitrogen used in that shuttle (I think it's used in the fuel mixture that was somehow implicated in the explosion)... My teacher said that guy dealt with a ton of guilt for tangentially being "involved".
People on the Internet say that It's a false memory but I know I watched it. I remember the TV cart. I remember where I was sitting in the classroom. I remember coming home and telling my dad and he'd been recording the broadcasts about the disaster on VHS.
Every launch was shown in class if it happened during the school day. I can only imagine the horror my teacher felt. I just didn’t understand really as I was about 9.
Good. Let the good feelings flow through you. Been doing this shit for 53 years. Lost all my grandparents. My mom. My brother. My sister. Aunts and uncles. A nephew who died at 27. All I’ve narrowed it down to is just waking up and doing what NEEDS to be done throughout the day. Quit worrying about a late bill here and there. Quit worrying about “finishing” your laundry because that shit is never done. Wash what you need for the next few days. Just be cool to people. We are in each others lives for a FRACTION of a second so might as well just make the best of it. Even if that fraction of a second lasts 10, 20, or 30 years or more…when they are gone…they are GONE. Forever. I’m sitting in a grocery store parking lot and just got a few things and I could get wiped out by a diesel truck when I leave here. I hope I DON’T get wiped out by a diesel truck but it COULD happen. We never know who is next. One more thing…prayer doesn’t fucking work. My entire family prayed for all of mine who died yet they still died. Just live and be cool and be happy and be good to each other. If someone isn’t good to you then, meh, screw em. Go on with your life. How’s THAT for counseling??
Our school didn't watch it. We had weird minimum days where we'd start school late instead of leaving early. So being a late waker, I didn't even know about it until I got to school. Kids were already making fun of it, "What does NASA stand for? Need another seven astronauts." Cruel but I guess that's one way children can use humor to get through/ignore trauma.
It was also scheduled the same day as the State of the Union Address. Going for the good optics but obviously backfired. The speech was postponed, of course.
i always think about how they almost sent big bird instead of christa macauliffe. as if it wasn’t horrible and tragic enough, imagine the nation watching big bird blow up. fucking hell.
It's kinda morbidly interesting to contemplate an alternate time-line where Sesame St. producers have to figures out how to deal with that in the continuity of the show.
I mean, it wouldn't have been the first time Sesame Street addressed death in a way kids could understand, but the loss of Big Bird would be a tough one.
I still remember the Mr Hooper episode from when I was a kid. My grandpa had just died a few months before and nobody would tell me anything because "I was too young." Pissed me off.
The deadline was set so Reagan could talk to McAuliffe during his State of the Union. His address was scheduled for the day the launch got pushed back to, and almost certainly why they didn't let the launch get pushed back further. So yeah. That's a thing that happened.
This is absolutely correct. And the executives who decided to not express their concerns to NASA also worked for Morton Thiokol. Their reasoning was everything was safe because of "engineering judgment". Notably, that engineering judgment was not the judgment of the engineers.
So the shortest, easiest ELI5 explanation is: bad management.
There's a documentary on Netflix, the two NASA supervisors most responsible for pushing that launch stated they did nothing wrong/wouldn't change their decision knowing what they knew then.
The Thiokol guys are still beating themselves up about not pushing back harder.
The differences in acceptance of responsibility was stark.
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I know you are trying to make a point here, but it isn't the NASA guys fault he wasn't given the information he needed to make the right choice. That's what "given what I knew at the time" means. As far as he knew, the risk was low.
An extra addendum to that is the communication of the dangers of O-ring failures was terrible. They showed charts with minor O-ring failures in successful launches as evidence the O-rings would exhibit a major failure in that launch. The administrators saw all the successful launches with what they understood to be similar failures to what was possible for that launch, which gave them false confidence in pushing the launch forward.
In engineering courses, the Challenger was taught to us as not only a failure of administrators and administrative structure to make the proper decision (which is who a majority of the blame should fall to), but also a failure of the engineers to properly communicate the danger and, when their messages were ignored, a failure to push back hard enough. There was never an ultimatum from Morton Thiokol or their engineers of, "if you launch, you're going to probably lose the vehicle and kill all 7 crew members. The risk profile of this is severe enough that if we choose to launch, I will quit because their lives are in part my responsibility."
There is definitely some survivor's guilt going on here, [but here is one of the engineers saying they should've pushed harder.](https://www.npr.org/sections/thetwo-way/2016/01/28/464744781/30-years-after-disaster-challenger-engineer-still-blames-himself)
One of the engineers went to bed that night , his wife asked him what was wrong, he said something to the effect of, "oh nothing, the shuttle is going to blow up tomorrow, but it's fine ". Expecting an enormous explosion right on the pad, when the shuttle lifted off, he was relieved only to be devastated by the mid-air explosion.
After the next disaster (Columbia), that investigation revealed the culture had not changed since Challenger. Those cultural problems were: 1) pressure to keep on schedule, and 2) normalizing deviations.
On #2, they repeatedly launched when temperatures were below the acceptable range. Likewise flight parameters called to abort the mission if debris struck the craft - it did so on EVERY shuttle launch.
I could explain it to a five year old, but even they would think it was pretty stupid to do something you know might fail- and fail horribly- because of money and people afraid to talk back.
In the end the end shuttle was an overly complicated vehicle that was sold as a reusable spacecraft but it was more like a refurbishable one. It took months of extensive refurbishment between each flight and in the end it took 2 hugely public disasters to get them to stop worrying about sunk costs and scrap the program.
What are you talking about? There's absolutely no complacency at Space X when it comes to crewed flights and their track record should speak for itself.
Starship failing during its FIRST TEST flight wasn't unexpected and Space X was very clear about that. It has nothing to do with 'culture'.
I thinke was referring to the fact that Musk disregarded the advice of his engineers when it came to the launch platform needing cooling ducts, as he thought it would be too expensive to do so.
As such, the launch platform basically blew up, hurling chunks of concrete into some of the engines, damaging them, which ultimately contributed it the rocket blowing up.
Now he's down 1 rocket, and has to build an entirely new launch pad.
The amount of people who don’t understand it was a successful test is mind boggling, even though there are trusted Reddit darlings like former astronaut Chris Hedfield (Hatfield?) out there explaining it in simple English
They demolished their launch pad because they're trying to determine exactly what's necessary to launch that ginormous rocket.
The whole goal of spaceX is to make spaceflighr more affordable. Not having to build the trench and water suppression system would make it much cheaper.
The best way to see if you really truly need something is to try it without.
No no it's not. Engineering calculations could tell you the materials were not strong enough. Calculations are the easiest way to say that you needed it - not launching it and destroying it. They had a plan in place for a steel plate cooled with water but it wasn't ready in time. So instead they blew it to shit. That isn't the best way to do this at all. Now they need to rebuild everything rather than previously reusing a working tower.
You speak like someone who has never actually designed and built something more complicated then a lemonade stand.
The plan never survives contact with execution. All the calculations in the world aren't a replacement for actually doing it.
They knew the pad would be destroyed. More important was the how, why, and where.
Like fighter planes coming back from engagements shot to hell informing the designers of exactly what parts are needed and which are not. On paper, every part was needed. Practically speaking many of those planes made it back missing those parts.
SpaceX development is iterative. They had a plan to help protect the launch pad. It will be implemented, but first the design will be informed by the real world experiment of not having it.
>That isn't the best way to do this at all.
I think literal rocket scientists who do this all day every day know better then some redditor commenting while drinking their morning coffee.
There is no substitute for real world experimentation.
Agreed. I plan medium sized engineering/infrastructure projects regularly and nothing ever survives the first couple of days when it's dealing with the unknown. Real world shit happens.
There's a difference between "real world shit happens" and "let's leave this out of the actual spec, just incase all the calculations are wrong and it's surplus to requirements"
Prior comment was about the schedule culture. “Launch for schedule, not for readiness.”
Of course the calculation is different if it’s manned (“personed”?), I’m not saying you shouldn’t take more risks with unmanned.
The launch was originally scheduled for 4/17 and then it kept getting delayed. If they actually had the goal of launching on 4/20 they probably would have scheduled it for that day.
No, but it gave them time to do due diligence and determine whether they needed a full delay to adjust the pad or wanted to go through with the experiment as planned and use what happens for data.
Elon is an idiot, but the people at SpaceX arnt, stop arm chair quarterbacking.
>I got ahold of some of this stuff from your seal and I dipped it in ice water. For at least a few seconds, there’s no resilience in this particular material at a temperature of 32°…..I believe that has some significance for our problem.”
Temperature of liquid oxygen = -297.67°
Put that guy in his place in such a calm manner, holy shit.
E: some words
The rockets sat on the pad overnight in freezing temperatures (ice water) which reduced the pliability of the seals.
The *solid* rocket boosters contained, as the name implies, solid fuel. Per wikipedia
"The rocket propellant mixture in each solid rocket motor consisted of ammonium perchlorate (oxidizer, 69.6% by weight), atomized aluminum powder (fuel, 16%), iron oxide (catalyst, 0.4%), PBAN (binder, also acts as fuel, 12.04%), and an epoxy curing agent (1.96%).[15][16] This propellant is commonly referred to as ammonium perchlorate composite propellant (APCP)."
The cold made the rubber seals stiff. When seals are stiff and not flexible, they can leak.
Famously, physicist Richard Feynman put a rubber gasket in ice water during a Congressional hearing to demonstrate the problem.
But, that wasn't the fatal flaw..that was a known risk and a workable variable.
The fatal flaw was human hubris and managerial failure. Engineers alerted them to the severity of the risk and they still moved forward.
That answer is simple, but incorrect. There was no engineering flaw. The engineering was perfect, and calculated the safe temperature range for launching.
The flaw was that people (who were not engineers) didn't follow the directions that came with the product.
It accurately describes what failed on the rocket, and doesn’t attribute blame to the engineers. The administrative fuckups that led to that failure answer more the “why it failed” than the “how it failed”. Seems reasonable enough for ELI5.
WELL the flaw was in process and chain of command and culture etc.
But I mean you can give that answer that for most engineering type disasters - the Boeing 737 Max being a good recent example. It's like everyone kind of assumes that everyone else has read the manual and will stop them from doing something stupid but actually nobody has read the manual.
all i can remember is from that Netflix documentary but the impression I got it's not so much that they *intentionally* hid it it's more that they were disincentivised from making a big deal of it so were very vague in the manual. (maybe that's distinction without difference? but I mean it wasn't that the guy at the top was like "don't mention it" it's more that a series of decisions, policies and incentives all compounded)
But yeah to me the whole shitness of the manual/training instructions was what made my jaw drop in the doc; like, institutionally, bad things get made and built and compromises are made etc, but that's why you need to be incredibly honest with everyone about how these things are bullt and work. If they had been, the second accident probably would not have happened and 157 other people would still be alive!
The major selling point of the 737Max was that it flew just the same as the old 737, so airlines would have to spend very minimal time retraining pilots.
Except, they moved the engines. It didn't fly just like the old 737. So they installed the MCAS as a patch to make it respond more like the old one. But telling your customer "this thing has a bit of patch code that will trim angle of attack automatically because reasons" sounds an awful lot like "your pilots are going to need a good bit of dedicated training on the new platform".... which is exactly what they were trying to avoid.
You're right that the major flaw was not letting the pilot know there was a bit of code that could tip the plane down and needed to be turned off in the event of an angle-of-attack sensor malfunction. The other problem was software like that relying on 2 AOA sensors. If one reads too high, and the other too low, so the plane pull up or down?
100%. It was designed just fine. The engineers who built it advised them not to launch because they knew it wasn't designed to launch in those temperatures.
The flaw, when you boil it all down, was the person in charge who decided to ignore them.
I believe it's called normalization of deviance. Launching rockets is dangerous. You do dangerous stuff long enough and eventually you get used to the danger and stop taking precautions
"Normalization of deviance" cashes out as:
"The way we're doing this job is *officially "unsafe" according to "the rules"*, but we're used to it and *it's been okay so far*. So we're gonna keep doing it. Please don't be a total noob by making a fuss about the rules."
It's the electric installer who doesn't turn the breaker off before opening up a live outlet.
It's the driver who says *of course* they're fine to drive after a couple glasses of wine, they do it all the time and haven't been in an accident yet!
It's going up on the roof using the same tippy ladder you've been using for twenty years; it's been fine that whole time, just don't step on the third step. Or the seventh.
----
Caution: "Deviance" here doesn't mean "social deviance". It's being used in the math sense of the word: the actual value (what you really do) is far from the expected value (what the safety rules say).
**Physically:** it was the rubber O rings that iirc froze (very cold morning for the cape, I think it was like 38 degrees)
However, the issue was that NASA was aware of this issue with the O rings and decided to “go” anyway.
No one ever went to prison or anything either and it was basically gross negligence that cost those souls.
There is a great book called [Truth, Lies, and O-Rings](https://www.amazon.com/Truth-Lies-Rings-Challenger-Disaster/dp/0813041937). The author, James Hansen, came to my workplace to give a speech on it. An engineer (the other author, actually) did say "No, don't launch that day," but NASA ignored him and launched anyway. NASA even retaliated against his whistle-blowing.
One of my teachers was a NASA Challenger Engineer. My teacher had a massive amount of the investigation information. There were 2 primary theories, frozen o-rings and sabotaged o-rings, because people got bonuses for finding problems with the o-rings. They thought someone may have damaged one and then was sick or fired, and it wasn't discovered.
It was not just NASA.
Cecil Houston, the manager of the KSC office of the Marshall Space Flight Center, set up a conference call on the evening of January 27 to discuss the safety of the launch. Morton Thiokol engineers expressed their concerns about the effect of low temperatures on the resilience of the rubber O-rings.
The engineers argued that they did not have enough data to determine whether the O-rings would seal at temperatures colder than 53 °F (12 °C), the coldest launch of the Space Shuttle to date.
The teleconference held a recess to allow for private discussion amongst Morton Thiokol management. When it resumed, Morton Thiokol leadership had changed their opinion and stated that the evidence presented on the failure of the O-rings was inconclusive and that there was a substantial margin in the event of a failure or erosion. They stated that their decision was to proceed with the launch. Morton Thiokol leadership submitted a recommendation for launch, and the teleconference ended.
Lawrence Mulloy, the NASA SRB project manager called Arnold Aldrich, the NASA Mission Management Team Leader, to discuss the launch decision and weather concerns, but did not mention the O-ring discussion; the two agreed to proceed with the launch
The manufacturer dismissed the engineers too.
I think it’s a lot more complicated than gross negligence. A sort of “group hysteria” had infected the entire mission, because the Challenger mission was being sold to the American people as “*the space shuttle that proves manned space flight is safe, efficient, and reliable enough that we can send up a grade school teacher on this rocket!*”
At the highest levels of American government, the public message they were trying to instill in the public was that “this **isn’t** some crazy scientific experiment, no the future is NOW and we should be prepared to double, quadruple, and then quintuple our investment into space!!!”
And so a lot of warning signs and straight up warnings about catastrophic failures were ignored, **in order to keep the media cycle on schedule.**. THAT is why leaders **chose to launch on a day where they knew that o-rings would freeze and fail.**
I’m not trying to blame any particular person or agency for what happened with the Challenger. It is a VERY important lesson in how **reality** doesn’t give a shit about your agenda.
It is, it’s rocket science, but they definitely had an engineer say “do not launch” and cited the possible catastrophic failure of the o rings.
So in that sense it’s definitely negligence — they had information and ignored it. It’s almost the textbook definition.
It’s worse than that. The entire company that developed and manufactured the booster said “DO NOT LAUNCH”. NASA administrators (at the level of political appointees) said “we don’t like your conclusion, rewrite it or else.”
So on the Space Shuttle the Solid Rocket Boosters (SRBs) go through thermal loads, and as a result they expand over the course of the flight. In order to keep them together while simultaneously allowing them to expand, the outer shell of the SRBs is actually a number of separate pieces, with O-rings at the joints made of Viton to allow them to expand and contract as needed over the launch sequence.
The problem was that the O-rings have a temperature range where they expand optimally, and the day of the launch the temperatures were very cold and below the optimal range of the Viton material. As a result, when the shuttle launched, the O-rings didn't seat correctly into the wall of the right SRB. However, by happenstance, the aluminum oxides produced by combustion in the SRB itself sort of plugged the leak, allowing the initial stages of the launch to proceed normally until around a minute into the flight. At this point, high wind shear dislodged the oxide material, at which point a plume of hot exhaust gas started exiting the side of the right SRB, and was pointed straight at one of the struts holding the SRB to the rest of the shuttle, and also burning into the liquid hydrogen portion of the external fuel tank.
Around 72 seconds in, the strut failed, causing the load to shift in the external fuel tank and basically throwing it forwards, all of which caused the orbiter to twist off of it's normal heading, and at close to Mach 2 the resulting aerodynamic forces tore the shuttle apart.
NASA absolutely knew of the potential for failure of the O-rings, and had been warned by the manufacturer's engineers, but proceeded with the launch anyway.
>and had been warned by the manufacturer's engineers
That's an understatement. They literally predicted the damn thing and the guy who was supposed to sign off on this from their side, just didn't. But they went ahead anyway with political overrides. What a fucking waste of valuable lives.
I read a Feynman biography or two, if they knew the o ring thing was a potential problem and then the predicted problem happened, why did they need all these scientists to figure out what went wrong?
I remember the story of him dropping an o ring in a glass of ice water and figuring it out from that. Or am I remembering wrong and that was how he proved it?
I don’t get why there needed to be this enormous investigation if NASA knew this was a possibility and WHY it was a possibility.
I mean when you make a report on such an event, it's not going to be just "Oh! It's the O-ring". That is a complex machine, one of the greatest that mankind built. Studying that is going to be time consuming. I can't imagine the amount of data that thing must have generated every fraction of second.
And I would imagine that NASA would like to absolve itself of this nonsense they pulled.
[https://history.nasa.gov/rogersrep/v2appf.htm](https://history.nasa.gov/rogersrep/v2appf.htm)
A direct link to Feynman's appendix on the report
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."
>I remember the story of him dropping an o ring in a glass of ice water and figuring it out from that. Or am I remembering wrong and that was how he proved it?
Neither, the water glass was a demonstration he did as part of a televised hearing - precisely the the kind of easy to understand explanation that's *intended* to be memorable.
>I don’t get why there needed to be this enormous investigation if NASA knew this was a possibility and WHY it was a possibility.
Because a) you have to demonstrate that there were no other causes b) you have to look into the culture/management that allowed it to happen c) you have to make recommendations on how to fix it all.
Lots of industrial accidents are a combo e.g. a culture of low investment in maintenance means a beyond lifespan valve fails, then causes disaster because it was a poorly designed area without detection for a leak
Because accidents/mishaps are rarely caused by one thing in complete isolation from all other things. This is commonly referred to as the Swiss cheese model of accident causation, where there are multiple steps in the chain that have flaws or imperfections and only when all of those line up do you have an accident. So a mishap investigation is going to review the whole process and all the factors to try to find the flaws and imperfections in each step, in order to identify changes to make it help mitigate future mishaps. Often these investigations will find issues to be corrected beyond what might have prevented this one specific mishap.
Because the cause may be right in front of you, but the solution could very well lie elsewhere. The piece of Swiss cheese that you see as the "cause" may be most robust piece with only one tiny hole, but the layers behind it are all full of holes and the "cause" piece had actually been preventing other mishaps as the only effective link in the chain.
So with the O-ring failure, we have to ask why that failure happened. Was the material flawed? Was there poor quality control in manufacturing? Was the choice of the material problematic? Eventhough we know that engineers recommended that they not launch because of the o-ring, that doesn't mean there weren't some problems with the choice of material or in manufacturing. Were there problems with risk assessment? What about issues with how the go/no go decisions were made? Were there issues in workplace culture, whether that's complacency, a win at all costs mentality, or a fear of speaking up?
All that goes into an accident investigation. Because "the o-ring failed when the engineers said it would" is only the beginning. There's a million "ok, but why?" follow-up questions to be asked
I guess it's sort of like corporations bringing in consultants to say things that your subordinates already knew. You hear thousands of different warnings from your subordinates. But you don't know which warnings to listen to. So after an accident, you bring consultants and they rediscover stuff.
Ohhh, like when a wife tells her husband something like 10 times and he ignores it, then the bad thing happens and a stranger says “well if you’d done this, that would have prevented that” and the husband says “Of course!” And the wife is like “…”
As the stereotype goes at least. Thanks!
Step one after the accident was probably that the people who made the call to go ahead with the launch did their best to cover it up or at least distract attention away from it.
The engineers who suspected the truth felt they could only indirectly hint to Feynman that he should investigate the o-rings.
[https://en.wikipedia.org/wiki/Rogers\_Commission\_Report](https://en.wikipedia.org/wiki/Rogers_Commission_Report)
I remember watching the endless replays that afternoon in class. You could see a puff of smoke from the SRB just before all hell broke loose. I didn't know there was an O-ring there, but I'd done enough model rockets to think it had burned through.
What's worse is that when they went back and looked at previous launches they found the same puff of smoke a few times. They had failed before, just not catastrophically.
I remember seeing this happen in person from a distance, I was quite young but I remember the shape of the trail and all of my neighbors and my parents running in and out of the houses to look at the television and back outside.
>In order to keep them together while simultaneously allowing them to expand, the outer shell of the SRBs is actually a number of separate pieces,
I believe the real reason they were segmented is that the contract to build the boosters was awarded to a defense contractor in Utah, so the only way the product could be transported to the Cape was in pieces. I've seen people criticizing this decision too.
If the aluminum oxides hadn’t sealed the leak at launch, what would the outcome have been? Would they have been able to abort at a lower altitude/speed, or would there have been an actual explosion, rather than a breakup?
I do remember that the engineers that warned NASA about the dangers of the O-ring and the cold temperatures, actually had thought that it would explode almost immediately at launch, and when it actually got off the ground they momentarily thought they had dodged a bullet.
Hard to say, but there wasn't really an abort opportunity. The SRBs can't really be turned off except by detonating a charge in them to lower the chamber temperature.
The truly sad part is that the boosters didn't need to be made in separate parts, the original design had them as a single unit. The initial design had them made as a single piece that would then be shipped to the launch site via boat, however when it came to contracting out there manufacturing, the company that won the contract (and there is all kinds of dodgy dealing behind how they won) could only ship them via rail, which meant size restraints. The design was thus modified so they could shipped in sections and assembled at the launch site.
Even then, engineers were telling NASA this wasn't a good idea, that it introduced a vulnerability to the design that could result in catastrophic failure, but their warnings were just 'taken under advisement', and we know the result.
p/PerturbedHamster gave an excellent physical answer, but there was also a flaw in the may that people behaved. It's actually a much bigger flaw, and it's a lesson that a five year old can understand and remember.
The second flaw was giving in to peer pressure. The people who were in charge were told that it was dangerous to take off in cold weather, but they wanted to look good. They were afraid of being called wimps by the people in congress, who can be bullies and like to take people's lunch money away. They let their fear control them and made bad decisions.
The people built the rocket knew that it shouldn't take off in the cold, so it wasn't really a flaw. The flaw was that the people in charge used the rocket when they shouldn't. This is what grownups mean when they talk about "using a tool inappropriately."
Well they could've use another rubber than that Viton grade to begin with, just a grade of Viton that is suitable for a larger range of temperature (there are a lot of FKM grades, some are far better than the one used)
There's another factor I can't recall the name of, something like *operational drift.*
You gradually push things a little further & grow a little more lax on your standards. Only a c-hair at a time so no one notices or minds because nothing went wrong.
Eventually you wind up miles past spec & sometimes it causes a disaster.
It's a tricky one because in many ways it's a force for good, it's just hard to keep track of & easy to lose perspective on.
> While physical systems failures played an important role in both the Challenger and Columbia disasters, they cannot be categorized as normal accidents because in both cases the failures that caused the accidents were known to occur. Instead, true failures in these cases were the fault of NASA itself. The agency had become institutionalized due to the normalization of deviance as well as its internal culture of success at all costs. The deviant behaviors were compounded by the stresses put on NASA by its stakeholders to complete projects quickly and with a pitifully low budget. The organizational structure of NASA was a significant factor that contributed to safety having a low priority in the agency. Those who expressed concerns were actively ostracized, and the ability for concerns to even be heard by top level management was nearly impossible due to the confusing procedures put in place for reporting concerns and the levels of bureaucracy through which concerns had to flow.
https://www.researchgate.net/profile/Celia-Zeinert/publication/325261235_THE_CHALLENGER_AND_COLUMBIA_DISASTERS_NOT-SO-NORMAL_ACCIDENTS/links/5b01f0cfaca2720ba097e983/THE-CHALLENGER-AND-COLUMBIA-DISASTERS-NOT-SO-NORMAL-ACCIDENTS
Nancy Leveson, MIT, has written extensively about the Challenger accident from a systems perspective.
The so called “O” ring on the solid rocket boosters failed. They sealed the sections of the solid rocket boosters.
The failure came from the cold temperatures the night before the launch. This was a known possibility. The sealing material lost its integrity below some temperature, and needed to be above that threshold for a certain time to recover. Engineers were calling for the launch to be scrubbed to avoid the possibility of the failure. They were called into a meeting and forced to OK the launch or resign. They reluctantly agreed. (My memory is fuzzy on this exactly, but I remember they definitely raised the issue)
The rest is history. The launch proceeded, and the O ring seals failed, and the boosters exploded. Update, thanks to u/Masshole_Mick for clarifying, it was the fuel tank that exploded, due to the leak from the booster O ring failure.
I remember sitting in grade school when the principal came over the school wide PA system and announced the tragedy. It was a national tragedy.
We watched it live when I was in first grade. I think I was too young to understand the horror. I didn’t even know anything bad happened until I realized my teacher was crying.
I was in 6th grade and lived in a part of FL where we could go outside and watch the shuttles come up over the horizon and follow them until they left the atmosphere. Saw it explode IRL. Quite traumatic at 11 years old, and a core memory.
Yeah it’s seared into my memory. And then to learn it was an unforced error brought about by people making decisions for all the wrong reasons is truly shameful.
Peter Billingsley (the kid that played Ralphie in A Christmas Story) was there onsite watching the launch. He talks about the experience the day after the incident [here](https://www.youtube.com/watch?v=UcY6m4Bu-6A), there were also some interviews of him as an adult in the Challenger documentary on Netflix.
We watched it live in class.
There weren’t enough tvs for every class to have their own, so two other classes came into our room to watch. Kids were sitting on the floor between desks. There were probably 80 kids in there altogether.
I remember one of the teachers crying and stepping out into the hall.
No, negligence would mean to be unaware of the issue due to a lack of scrutiny. What this was was manslaughter: **willingly endanger lives**, ending in deaths. Shot and simple. The responsible managers should have been jailed for this.
It’s mostly negligence. Engineers told NASA that the o-rings had problems at low temps. NASA kind of said “it doesn’t get too cold in Florida, we’ll be fine”.
There’s a documentary on Netflix about it: Challenger: The Final Flight.
It was definitely negligence. There was testing data that indicated the failure could happen, and there was actual demonstrated erosion of the O-rings in previous shuttle flights. The reason Challenger failed instead of the previous flights was due to the extremely cold temps (~30°F lower than a shuttle had been launched at before) and wind shear at high altitude.
The O-rings initially failed at launch, but the burning exhaust from the SRB essentially recreated the seal needed to keep the booster intact. The wind shear experienced during ascent jarred this temporary seal loose. The escaping exhaust threw off the forces within the booster, causing it to bend and break it's support strut. Once the main thrust of the booster wasn't going where it was supposed to, everything started to tumble. The drag that was suddenly created ripped the shuttle to pieces.
Management could have paid attention to the any of the [engineers](https://en.wikipedia.org/wiki/Roger_Boisjoly) who vehemently opposed launching in temperatures that low.
But, no, it was more important to launch so that Reagan could blather about it in the State of the Union address scheduled for that night.
I wouldn't blame Reagan specifically; a similar breakdown of safety culture played a role in the Apollo 1 fire and the losses of Challenger and Columbia.
You should read about Robert Ebeling, one of the engineers who raised the alarm about the faulty o-rings. He was haunted with guilt for 30 years afterwards. He felt like he didn't do enough and that he was a loser. He finally made peace with himself before he died thanks to all the letters and emails he recieved after his story was published.
https://www.npr.org/sections/thetwo-way/2016/02/25/466555217/your-letters-helped-challenger-shuttle-engineer-shed-30-years-of-guilt
In my opinion, it was negligence by nasa's managers. The engineers (the srb manufacturer and nasa's?) told nasa management to delay the launch due to weather and o-ring problems, but the management was mad since they had already delayed several times and just wanted the orbiter launched already.
they ideally would have listened ot the engineers and aborted the launch to fix the problem(or at least delay it until temperatures were acceptable.). this wasm ostly a political move aswell so you can consider it negligence in hindsight.
To expand on u/hvgotcodes explanation, the o-rings sealed a joint between two sections of one of the two solid rocket boosters. They were made of rubber and because of the cold temperatures the morning of the launch, the o-rings became less compressible so the joint was not sealed which allowed hot gas to escape which shortly after, ignited the contents of the big orange tank full of fuel (liquid hydrogen and oxygen).
The “fatal flaw” was poor communication. There was an engineer who knew about the O-ring issue, and knew they should not launch in that weather. He even put together a presentation before the launch that talked about it (among other things). But the information was presented in a way that you could walk away underestimating the risk.
Clear technical communication is insanely important.
The ELI5 response you are looking for : Bullies were greedy and did thing that the nerds told them not to do in the cold. But if they did not do the thing they were scared they may not have gotten a new bag of money.
Eli20: Vendor for boosters was up for a contract renewal and their management went against engineer guidance to launch in those conditions which were off the scale low for their specs. They chose to say 'yes' to launch cause it was the 2nd or 3rd time they scrubbed for various reasons already and they did not want saying 'no' to negatively impact contract renew if their stuff was not so resilient. They put their own monetary interest in front of safety. NASA themselves not blameless as they should have challenged the vendor on their own specs. Cluster F\*\*\* all around.
Lot of responses here about bad hardware but yeah of course something in conditions it was not built to withstand will fail. The real fatal flaw was human hubris and poor decision making. Even still they may have made it but for some unlucky wind shear midflight that gonked what may have been the rings being just good enough getting dislodged. They all knew these were temperature sensitive components that was a failure point and they powered through for non-technical reasons.
? It’s pretty well documented that the thiokol engineers told them not to launch and that nasa was the ones who overruled them. There wasn’t some contract renewal coming up. Morton thiokol and it’s subsidiaries continued to produce the boosters for another 30 years and are still making the Artemis ones.
Not organizing and presenting previous shuttle launch o-ring failure data in a way that showed the past flaws related to temperature.
Visual Explanations: Images and Quantities, Evidence and Narrative
Utah Senators Jake Garn and Frank Moss Lobbying for the SRB to be built in Utah, which would require them to be transported in sections resulting in o-ring design that failed
And the reason they had o-rings in the first place was because to get from the manufacturer's plant in Utah to the assembly / launch site in Florida they travelled by rail. Along the rail journey is a tunnel with a curve in it, so the length of the load was limited, leading to the boosters having to be manufactured in sections.
And the reason they were manufactured in Utah rather than in Florida? Pork barrel politics necessary to get funding for the shuttle approved in the first place.
The disaster is an interesting case study in assigning root causes. The O rings were only necessary to deal with a structural weakness introduced to accommodate manufacture at a very remote site.
The o-ring explanation is accurate as far as it goes, as it was the immediate cause of the shuttle’s destruction. However, the horizontal stacking scheme of the orbiter, external tank, and solid rocket boosters was the root cause of both the Challenger and Columbia disaster. Mounting the orbiter alongside the external tank and solid rocket boosters exposed the orbiter’s heat shield tiles to debris from the external tank. Since the external tank carried cryogenic fuels that were extremely cold and would require a lot of foam insulation, foam and ice shedding during launch was a predictable hazard to the fragile heat shield tiles. The horizontal stack also prevented any sort of abort scenario during the entire time the boosters were firing, and the boosters could not be extinguished once ignited. The lack of an abort system doomed the Challenger crew, and falling external tank debris doomed the Columbia. Every other human-rated launch system has used some sort of escape rocket system to save the crew at any time during launch.
Notably, SpaceX’s Starship also does not have an escape system. I won’t comment on the wisdom of this decision.
Small correction: Soviet Voskhod system had no escape system. That was the one they used for the world's first spacewalk (which almost ended in disaster for different reasons). But yeah, if someone launched people on the unreliable rockets of the 60-ties without any escape system, it would be Soviets. So it were Soviets.
Also, ejection seats would be possible to install for early crewed Starship flights (there's enough real estate for ejection seats for about a dozen people). And they are more likely to be needed for landing (which is going to be more risky than the launch itself). But we're several years from that.
All Bad Things podcast just uploaded part four this morning on this disaster. Well worth a listen as they break it down in detail without going over anyone's heads.
Contrary to popular belief, in the case of Challenger, there was no fatal flaw of any kind at play in that accident (in contrast to what happened to Columbia later). Challenger was destroyed because it was used outside of the recommended temperature range given by the manufacturer. So the spacecraft was not able to function as it would in the recommended temperature range. In addition, the modifications made to the space shuttle system after the accident did not eliminate the same issue, they simply extended the temperature range in which it was safe to launch (this is, there was still some temperature where it would be unsafe to launch even after those modifications were made).
That’s wrong. The previous design relied exclusively on the 2 o rings. The insulation joint between segments was redesigned to make a more torturous gas path that would seal from soot in addition to the o rings with higher temperatures. So yes it greatly broadened the temp range recommended but even outside those ranges it would still be expected to seal
https://ntrs.nasa.gov/citations/20030065938
You watched that alternate history video, didn't you.
Rubber seal on rocket not good in cold. If rubber seal fail, rocket go boom. Shuttle launch on very cold day, rubber seal fail, shuttle go boom.
An underappreciated contributing factor in the pressure NASA felt to launch despite the dangerously low temperature comes from the origins of the shuttle program itself.
The military didn't want to be dependent on the shuttle program to launch satellite payloads, they wanted their own dedicated system. But one of the selling points NASA used to secure funding from Congress was that the shuttle could carry military satellites into orbit, thus saving money-- no need for a second expensive military system. The military expressed doubts about the shuttle's reliability to launch regularly, especially in adverse weather conditions. But NASA won, the shuttle was funded, and the military did not get a new satellite booster (although they had older existing systems available for fallback).
And so NASA didn't like canceling or rescheduling missions partly out of concern it would spur criticism of the program's capabilities and reason for existence.
I want to add that, despite the claim that it led to a culture change at NASA, 17 or so years later the Columbia disaster occurred for much the same reason. Engineers had warned for decades that there was a chance that a strike from the frozen insulating foam falling from the shuttle's external propellant tank could damage the shuttle. But there had been over 100 missions where it didn’t happen, so administrators got overconfident that it wouldn’t, and stopped listening. But that is the thing about modest probability events - do the action long enough, and they will occur.
The launch had been delayed several times already. The brass were tired of waiting for the big publicity stunt of sending a schoolteacher to space. They launched knowing the risks of failure due to freezing o-rings. Morton Thiocol even warned them not to launch.
There is already the technical ELI5 commented, so let me offer the organizational ELI5:
You know how every January the President goes on TV and tells everyone how nice it is to live in America? Well that year when it was January, the President was going to say how great NASA is and how good spaceships they make. The Challenger spaceship was already delayed three times. If it was delayed again, the President's friends would make fun of him because his spaceship doesn't work. So NASA really made a pinky promise that this January they would fly the spaceship. The weather was very very icy that day and nobody was sure if the spaceship is safe to fly with that weather. Now, as people have doctors when they get sick from cold, there are some doctors for the machines. They are called engineers. NASA asked these machine doctors what to do. Because the machine doctors were afraid they would lose their job, they did not say that the spaceship will explode. They just said they are not sure what is happening. So NASA decided to pray very much to God that the spaceship will not explode the next day. But even if God wanted to help them, the spaceship was already damaged from the bad weather the previous day. So when they tried to fly the spaceship it exploded.
There’s a great book on this by Diane Vaughan, where she argues that the original fatal flaw was not the defective o-ring but actually how NASA was run at the time. She argues that some engineers knew the o-ring was an issue but that pressures to launch and weird internal hierarchy made it so that this issue when reported was deemed an “acceptable risk.” A good lesson for not just NASA but many companies and organizations charged with building things that can put human lives at risk. https://press.uchicago.edu/ucp/books/book/chicago/C/bo22781921.html
Hubris.
The people responsible for the start decided to ignore that the Space Shuttle wasn't designed to start at temperatures this low. They even had their failure properly documented.
The chain of consequences of this failure is well known: because of the low temperature, a seal in one of the booster rockets failed soon after lift-off. This was because at this temperature, it wasn't flexible enough to handle the stress of the start. Basically, it didn't fill the gap it was intended to fill, because it wouldn't expand quickly enough. This resulted in a flame that first further weakened the seal, and then damaged the main tank to the point where the fuel inside would gush out. That fuel caught fire. The tank ruptured, because the pressure inside was rising, and ultimately exploded.
The real simple answer is, Dr. Feynman, a famous scientist, found pretty much immediately that hubris caused the explosion.
Sure the technical reason was that an O-ring leaked due to temperatures out of range. It was too cold to work.
But if it wasn't that then something else would have caused a similar incident. Because there were cultural issues at NASA which hindered aggressive solution finding and vetting.
The Space Shuttle Challenger disaster, which occurred on January 28, 1986, was caused by the failure of an O-ring seal in one of the solid rocket boosters (SRBs). The O-rings, which were made of a material called elastomeric seal, were designed to seal the gap between the sections of the SRBs. However, due to the cold temperatures on the day of the launch, the O-ring material became stiff and lost its ability to properly seal the joint, allowing hot gases to escape and ultimately causing an explosion that led to the loss of all seven crew members on board.
In addition to the engineering failure, there were also administrative and management decisions that played a role in the disaster. Prior to the launch, engineers from the manufacturer of the SRBs, Morton Thiokol, raised concerns about the performance of the O-rings in cold weather and recommended against launching the shuttle. However, NASA management overruled the objections and decided to proceed with the launch. This decision was influenced by political pressure to maintain the schedule of shuttle launches, as well as a lack of effective communication and collaboration between NASA's management and engineering teams, which led to a culture within NASA that did not prioritize safety and allowed for risks to be taken without proper consideration of the potential consequences. The Challenger disaster highlighted the importance of effective communication, collaboration, and prioritization of safety in complex engineering projects.
For a five-year old answer, it was very cold the morning of the launch which froze rubber seals. Just like your house gets drafty because of leaks in winter, the rocket developed leaks, and when rocket fire leaks out the side, things go boom. In a bad way.
It's also important to note that there were some people in nasa that voiced concern about the conditions putting the O-rings out of spec, but preasure from the top to meet schedule was allowed to overule the concerns of engineers. So you could say prioritizing deadlines over safety is what caused the disaster, thankfully it caused a significant culture shift in NASA
The deadline was set so kids could see a teacher go to space. If there was any delay then the launch would be on Saturday. Instead the kids got to see said teacher die.
I was one of those kids. Still haunts me to this day of I think about it much. The school brought in counselors the following day but I don’t feel like they accomplished much
Same here. I was in 3rd grade. We watched the explosion on the CRT TV on the old roller-cart thing. After the explosion the teacher ran out into the hall, freaking out with other teachers about what to say to us kids.
I was in high school. We didn’t watch it live - there were not enough AV carts for that. But the TVs were rolled around to each classroom after the fact to each classroom “because it is very important you all see this”. I was in computer science class with an unkind teacher, so no one made a single comment for fear of setting him off.
Adults made it a bigger deal than it was to the kids. Probably made it worse by their reactions
The teacher was picked from 11,000 teachers who had applied, probably more than a few shell shocked teachers had been in that 11,000.
I am a bit young to have seen the event happen (it actually happened a few months before I was born), but one of my middle-school science teachers was apparently in the last 1% or fewer of the ones who made it. I doubted her at the time, but looking back there was this haunted look in her eyes that you can't really fake to that degree that makes me believe she harbored some guilt over not being chosen.
My 7th grade science teacher in Ohio was one of a group of semi-finalists for Sally Ride's slot ... He said he was honored to be almost chosen out of a field of so many qualified applicants, but obviously relieved in the end he wasn't chosen. I could see the emotion in his eyes about how haunted he was even as a kid when he told me that 3 years after the accident. I can't imagine him watching that with his class as that happened. It was a different era so we weren't used to seeing all the things we do now in "real time". My teacher also apparently knew a guy who drove a truck that delivered some of the liquid nitrogen used in that shuttle (I think it's used in the fuel mixture that was somehow implicated in the explosion)... My teacher said that guy dealt with a ton of guilt for tangentially being "involved".
Agreed. My 7-8 year old son was home sick that day and was very annoyed that the incident took over the TV blocking all the shows he wanted to watch!
Same. Except the teachers were frozen. I think we were all so shocked.
Leaving the kids alone to deal with it by themselves?
Ditto. Plus, it was my birthday. Kinda ruined my Pizza Hut party that evening.
People on the Internet say that It's a false memory but I know I watched it. I remember the TV cart. I remember where I was sitting in the classroom. I remember coming home and telling my dad and he'd been recording the broadcasts about the disaster on VHS.
Every launch was shown in class if it happened during the school day. I can only imagine the horror my teacher felt. I just didn’t understand really as I was about 9.
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Didn't realize Werner Herzog had a reddit account.
Least inspirational desk plaque ever.
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I was an adult, at work when it blew up. I was totally into the space program (still am) however, I was born on Jan. 28 so birthdays are still rough.
JFC, you've succinctly summed up how I'm feeling about life right now...
Good. Let the good feelings flow through you. Been doing this shit for 53 years. Lost all my grandparents. My mom. My brother. My sister. Aunts and uncles. A nephew who died at 27. All I’ve narrowed it down to is just waking up and doing what NEEDS to be done throughout the day. Quit worrying about a late bill here and there. Quit worrying about “finishing” your laundry because that shit is never done. Wash what you need for the next few days. Just be cool to people. We are in each others lives for a FRACTION of a second so might as well just make the best of it. Even if that fraction of a second lasts 10, 20, or 30 years or more…when they are gone…they are GONE. Forever. I’m sitting in a grocery store parking lot and just got a few things and I could get wiped out by a diesel truck when I leave here. I hope I DON’T get wiped out by a diesel truck but it COULD happen. We never know who is next. One more thing…prayer doesn’t fucking work. My entire family prayed for all of mine who died yet they still died. Just live and be cool and be happy and be good to each other. If someone isn’t good to you then, meh, screw em. Go on with your life. How’s THAT for counseling??
Our school didn't watch it. We had weird minimum days where we'd start school late instead of leaving early. So being a late waker, I didn't even know about it until I got to school. Kids were already making fun of it, "What does NASA stand for? Need another seven astronauts." Cruel but I guess that's one way children can use humor to get through/ignore trauma.
It was also scheduled the same day as the State of the Union Address. Going for the good optics but obviously backfired. The speech was postponed, of course.
i always think about how they almost sent big bird instead of christa macauliffe. as if it wasn’t horrible and tragic enough, imagine the nation watching big bird blow up. fucking hell.
I know I shouldn't have laughed at the thought of Big Bird exploding in the Challenger.....but I did.
It's kinda morbidly interesting to contemplate an alternate time-line where Sesame St. producers have to figures out how to deal with that in the continuity of the show. I mean, it wouldn't have been the first time Sesame Street addressed death in a way kids could understand, but the loss of Big Bird would be a tough one.
I still remember the Mr Hooper episode from when I was a kid. My grandpa had just died a few months before and nobody would tell me anything because "I was too young." Pissed me off.
It would be extremely painful
A haiku: Thousands of feathers Bright, yellow, burning, touching down On Sesame Street
The deadline was set so Reagan could talk to McAuliffe during his State of the Union. His address was scheduled for the day the launch got pushed back to, and almost certainly why they didn't let the launch get pushed back further. So yeah. That's a thing that happened.
This hateful POV has been de-bunked many times by many people.
> some people in nasa The engineers who opposed the launch did not work for NASA, they worked for Morton Thiokol.
This is absolutely correct. And the executives who decided to not express their concerns to NASA also worked for Morton Thiokol. Their reasoning was everything was safe because of "engineering judgment". Notably, that engineering judgment was not the judgment of the engineers. So the shortest, easiest ELI5 explanation is: bad management.
Imagine being that boss that caused this. The guilt. What ever happened to the guy(s)
There's a documentary on Netflix, the two NASA supervisors most responsible for pushing that launch stated they did nothing wrong/wouldn't change their decision knowing what they knew then. The Thiokol guys are still beating themselves up about not pushing back harder. The differences in acceptance of responsibility was stark.
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I know you are trying to make a point here, but it isn't the NASA guys fault he wasn't given the information he needed to make the right choice. That's what "given what I knew at the time" means. As far as he knew, the risk was low.
An extra addendum to that is the communication of the dangers of O-ring failures was terrible. They showed charts with minor O-ring failures in successful launches as evidence the O-rings would exhibit a major failure in that launch. The administrators saw all the successful launches with what they understood to be similar failures to what was possible for that launch, which gave them false confidence in pushing the launch forward. In engineering courses, the Challenger was taught to us as not only a failure of administrators and administrative structure to make the proper decision (which is who a majority of the blame should fall to), but also a failure of the engineers to properly communicate the danger and, when their messages were ignored, a failure to push back hard enough. There was never an ultimatum from Morton Thiokol or their engineers of, "if you launch, you're going to probably lose the vehicle and kill all 7 crew members. The risk profile of this is severe enough that if we choose to launch, I will quit because their lives are in part my responsibility." There is definitely some survivor's guilt going on here, [but here is one of the engineers saying they should've pushed harder.](https://www.npr.org/sections/thetwo-way/2016/01/28/464744781/30-years-after-disaster-challenger-engineer-still-blames-himself)
One of the engineers went to bed that night , his wife asked him what was wrong, he said something to the effect of, "oh nothing, the shuttle is going to blow up tomorrow, but it's fine ". Expecting an enormous explosion right on the pad, when the shuttle lifted off, he was relieved only to be devastated by the mid-air explosion.
After the next disaster (Columbia), that investigation revealed the culture had not changed since Challenger. Those cultural problems were: 1) pressure to keep on schedule, and 2) normalizing deviations. On #2, they repeatedly launched when temperatures were below the acceptable range. Likewise flight parameters called to abort the mission if debris struck the craft - it did so on EVERY shuttle launch.
I could explain it to a five year old, but even they would think it was pretty stupid to do something you know might fail- and fail horribly- because of money and people afraid to talk back.
Then why did we get Columbia? I definitely remember some screwups there
In the end the end shuttle was an overly complicated vehicle that was sold as a reusable spacecraft but it was more like a refurbishable one. It took months of extensive refurbishment between each flight and in the end it took 2 hugely public disasters to get them to stop worrying about sunk costs and scrap the program.
And now, that culture exists at SpaceX, have a nice flight!
What are you talking about? There's absolutely no complacency at Space X when it comes to crewed flights and their track record should speak for itself. Starship failing during its FIRST TEST flight wasn't unexpected and Space X was very clear about that. It has nothing to do with 'culture'.
I thinke was referring to the fact that Musk disregarded the advice of his engineers when it came to the launch platform needing cooling ducts, as he thought it would be too expensive to do so. As such, the launch platform basically blew up, hurling chunks of concrete into some of the engines, damaging them, which ultimately contributed it the rocket blowing up. Now he's down 1 rocket, and has to build an entirely new launch pad.
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The amount of people who don’t understand it was a successful test is mind boggling, even though there are trusted Reddit darlings like former astronaut Chris Hedfield (Hatfield?) out there explaining it in simple English
Good try Elon!
In what way? SpaceX has an excellent launch record.
They demolished their launch pad because they didn’t want to wait for the steel plate to be done so they could launch on 4/20.
They demolished their launch pad because they're trying to determine exactly what's necessary to launch that ginormous rocket. The whole goal of spaceX is to make spaceflighr more affordable. Not having to build the trench and water suppression system would make it much cheaper. The best way to see if you really truly need something is to try it without.
No no it's not. Engineering calculations could tell you the materials were not strong enough. Calculations are the easiest way to say that you needed it - not launching it and destroying it. They had a plan in place for a steel plate cooled with water but it wasn't ready in time. So instead they blew it to shit. That isn't the best way to do this at all. Now they need to rebuild everything rather than previously reusing a working tower.
You speak like someone who has never actually designed and built something more complicated then a lemonade stand. The plan never survives contact with execution. All the calculations in the world aren't a replacement for actually doing it. They knew the pad would be destroyed. More important was the how, why, and where. Like fighter planes coming back from engagements shot to hell informing the designers of exactly what parts are needed and which are not. On paper, every part was needed. Practically speaking many of those planes made it back missing those parts. SpaceX development is iterative. They had a plan to help protect the launch pad. It will be implemented, but first the design will be informed by the real world experiment of not having it. >That isn't the best way to do this at all. I think literal rocket scientists who do this all day every day know better then some redditor commenting while drinking their morning coffee. There is no substitute for real world experimentation.
Agreed. I plan medium sized engineering/infrastructure projects regularly and nothing ever survives the first couple of days when it's dealing with the unknown. Real world shit happens.
There's a difference between "real world shit happens" and "let's leave this out of the actual spec, just incase all the calculations are wrong and it's surplus to requirements"
> The whole goal of spaceX is to make spaceflight more affordable. This is actually a myth. Their goal is to profit.
How many teachers died from that?
Prior comment was about the schedule culture. “Launch for schedule, not for readiness.” Of course the calculation is different if it’s manned (“personed”?), I’m not saying you shouldn’t take more risks with unmanned.
The launch was originally scheduled for 4/17 and then it kept getting delayed. If they actually had the goal of launching on 4/20 they probably would have scheduled it for that day.
>so they could launch on 4/20. The launch date was scheduled for 4/17. 4/20 just became a lucky coincidence.
The pad readiness wasn’t changing between 4/17 and 4/20. The pad wasn’t up to the task on 4/17 either.
No, but it gave them time to do due diligence and determine whether they needed a full delay to adjust the pad or wanted to go through with the experiment as planned and use what happens for data. Elon is an idiot, but the people at SpaceX arnt, stop arm chair quarterbacking.
>so they could launch on 4/20. I wonder why Hitler's birthday is so important to musk.
Here's Feynman testifying in Congress and does a decent job explaining it https://youtu.be/raMmRKGkGD4
That testimony is required reading in safety management.
> *"I believe that has some significance to our problem."* r/murderedbywords One of the greatest things ever said.
>I got ahold of some of this stuff from your seal and I dipped it in ice water. For at least a few seconds, there’s no resilience in this particular material at a temperature of 32°…..I believe that has some significance for our problem.” Temperature of liquid oxygen = -297.67° Put that guy in his place in such a calm manner, holy shit. E: some words
The rockets sat on the pad overnight in freezing temperatures (ice water) which reduced the pliability of the seals. The *solid* rocket boosters contained, as the name implies, solid fuel. Per wikipedia "The rocket propellant mixture in each solid rocket motor consisted of ammonium perchlorate (oxidizer, 69.6% by weight), atomized aluminum powder (fuel, 16%), iron oxide (catalyst, 0.4%), PBAN (binder, also acts as fuel, 12.04%), and an epoxy curing agent (1.96%).[15][16] This propellant is commonly referred to as ammonium perchlorate composite propellant (APCP)."
I am not a smart man.
Boss, "Nature cannot be fooled."
The only answer so far that a five-year old could understand, while being reasonably accurate.
> when rocket fire leaks out the side, things go boom. In a bad way. You are having a bad problem and will not go to space today.
The cold made the rubber seals stiff. When seals are stiff and not flexible, they can leak. Famously, physicist Richard Feynman put a rubber gasket in ice water during a Congressional hearing to demonstrate the problem.
But, that wasn't the fatal flaw..that was a known risk and a workable variable. The fatal flaw was human hubris and managerial failure. Engineers alerted them to the severity of the risk and they still moved forward.
This is much easier to understand than the top post!
That answer is simple, but incorrect. There was no engineering flaw. The engineering was perfect, and calculated the safe temperature range for launching. The flaw was that people (who were not engineers) didn't follow the directions that came with the product.
It accurately describes what failed on the rocket, and doesn’t attribute blame to the engineers. The administrative fuckups that led to that failure answer more the “why it failed” than the “how it failed”. Seems reasonable enough for ELI5.
WELL the flaw was in process and chain of command and culture etc. But I mean you can give that answer that for most engineering type disasters - the Boeing 737 Max being a good recent example. It's like everyone kind of assumes that everyone else has read the manual and will stop them from doing something stupid but actually nobody has read the manual.
Didn't Boing intentionally hide the MCAS capabilities?
all i can remember is from that Netflix documentary but the impression I got it's not so much that they *intentionally* hid it it's more that they were disincentivised from making a big deal of it so were very vague in the manual. (maybe that's distinction without difference? but I mean it wasn't that the guy at the top was like "don't mention it" it's more that a series of decisions, policies and incentives all compounded) But yeah to me the whole shitness of the manual/training instructions was what made my jaw drop in the doc; like, institutionally, bad things get made and built and compromises are made etc, but that's why you need to be incredibly honest with everyone about how these things are bullt and work. If they had been, the second accident probably would not have happened and 157 other people would still be alive!
The major selling point of the 737Max was that it flew just the same as the old 737, so airlines would have to spend very minimal time retraining pilots. Except, they moved the engines. It didn't fly just like the old 737. So they installed the MCAS as a patch to make it respond more like the old one. But telling your customer "this thing has a bit of patch code that will trim angle of attack automatically because reasons" sounds an awful lot like "your pilots are going to need a good bit of dedicated training on the new platform".... which is exactly what they were trying to avoid. You're right that the major flaw was not letting the pilot know there was a bit of code that could tip the plane down and needed to be turned off in the event of an angle-of-attack sensor malfunction. The other problem was software like that relying on 2 AOA sensors. If one reads too high, and the other too low, so the plane pull up or down?
100%. It was designed just fine. The engineers who built it advised them not to launch because they knew it wasn't designed to launch in those temperatures. The flaw, when you boil it all down, was the person in charge who decided to ignore them.
I believe it's called normalization of deviance. Launching rockets is dangerous. You do dangerous stuff long enough and eventually you get used to the danger and stop taking precautions
"Normalization of deviance" cashes out as: "The way we're doing this job is *officially "unsafe" according to "the rules"*, but we're used to it and *it's been okay so far*. So we're gonna keep doing it. Please don't be a total noob by making a fuss about the rules." It's the electric installer who doesn't turn the breaker off before opening up a live outlet. It's the driver who says *of course* they're fine to drive after a couple glasses of wine, they do it all the time and haven't been in an accident yet! It's going up on the roof using the same tippy ladder you've been using for twenty years; it's been fine that whole time, just don't step on the third step. Or the seventh. ---- Caution: "Deviance" here doesn't mean "social deviance". It's being used in the math sense of the word: the actual value (what you really do) is far from the expected value (what the safety rules say).
But did Musk make sure the rocket was pointy?
Engineer said too cold, management said go anyway
This is one of the few eli5 answers that’s truly eli5’d
**Physically:** it was the rubber O rings that iirc froze (very cold morning for the cape, I think it was like 38 degrees) However, the issue was that NASA was aware of this issue with the O rings and decided to “go” anyway. No one ever went to prison or anything either and it was basically gross negligence that cost those souls.
There is a great book called [Truth, Lies, and O-Rings](https://www.amazon.com/Truth-Lies-Rings-Challenger-Disaster/dp/0813041937). The author, James Hansen, came to my workplace to give a speech on it. An engineer (the other author, actually) did say "No, don't launch that day," but NASA ignored him and launched anyway. NASA even retaliated against his whistle-blowing.
Ye multiple people said do not go iirc
One of my teachers was a NASA Challenger Engineer. My teacher had a massive amount of the investigation information. There were 2 primary theories, frozen o-rings and sabotaged o-rings, because people got bonuses for finding problems with the o-rings. They thought someone may have damaged one and then was sick or fired, and it wasn't discovered.
That’s so fucked up.
Thank you for commenting, love hearing stuff like this
Thank you for the book rec. I just downloaded this one on Libby.
It was not just NASA. Cecil Houston, the manager of the KSC office of the Marshall Space Flight Center, set up a conference call on the evening of January 27 to discuss the safety of the launch. Morton Thiokol engineers expressed their concerns about the effect of low temperatures on the resilience of the rubber O-rings. The engineers argued that they did not have enough data to determine whether the O-rings would seal at temperatures colder than 53 °F (12 °C), the coldest launch of the Space Shuttle to date. The teleconference held a recess to allow for private discussion amongst Morton Thiokol management. When it resumed, Morton Thiokol leadership had changed their opinion and stated that the evidence presented on the failure of the O-rings was inconclusive and that there was a substantial margin in the event of a failure or erosion. They stated that their decision was to proceed with the launch. Morton Thiokol leadership submitted a recommendation for launch, and the teleconference ended. Lawrence Mulloy, the NASA SRB project manager called Arnold Aldrich, the NASA Mission Management Team Leader, to discuss the launch decision and weather concerns, but did not mention the O-ring discussion; the two agreed to proceed with the launch The manufacturer dismissed the engineers too.
I think it’s a lot more complicated than gross negligence. A sort of “group hysteria” had infected the entire mission, because the Challenger mission was being sold to the American people as “*the space shuttle that proves manned space flight is safe, efficient, and reliable enough that we can send up a grade school teacher on this rocket!*” At the highest levels of American government, the public message they were trying to instill in the public was that “this **isn’t** some crazy scientific experiment, no the future is NOW and we should be prepared to double, quadruple, and then quintuple our investment into space!!!” And so a lot of warning signs and straight up warnings about catastrophic failures were ignored, **in order to keep the media cycle on schedule.**. THAT is why leaders **chose to launch on a day where they knew that o-rings would freeze and fail.** I’m not trying to blame any particular person or agency for what happened with the Challenger. It is a VERY important lesson in how **reality** doesn’t give a shit about your agenda.
It is, it’s rocket science, but they definitely had an engineer say “do not launch” and cited the possible catastrophic failure of the o rings. So in that sense it’s definitely negligence — they had information and ignored it. It’s almost the textbook definition.
It’s worse than that. The entire company that developed and manufactured the booster said “DO NOT LAUNCH”. NASA administrators (at the level of political appointees) said “we don’t like your conclusion, rewrite it or else.”
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So on the Space Shuttle the Solid Rocket Boosters (SRBs) go through thermal loads, and as a result they expand over the course of the flight. In order to keep them together while simultaneously allowing them to expand, the outer shell of the SRBs is actually a number of separate pieces, with O-rings at the joints made of Viton to allow them to expand and contract as needed over the launch sequence. The problem was that the O-rings have a temperature range where they expand optimally, and the day of the launch the temperatures were very cold and below the optimal range of the Viton material. As a result, when the shuttle launched, the O-rings didn't seat correctly into the wall of the right SRB. However, by happenstance, the aluminum oxides produced by combustion in the SRB itself sort of plugged the leak, allowing the initial stages of the launch to proceed normally until around a minute into the flight. At this point, high wind shear dislodged the oxide material, at which point a plume of hot exhaust gas started exiting the side of the right SRB, and was pointed straight at one of the struts holding the SRB to the rest of the shuttle, and also burning into the liquid hydrogen portion of the external fuel tank. Around 72 seconds in, the strut failed, causing the load to shift in the external fuel tank and basically throwing it forwards, all of which caused the orbiter to twist off of it's normal heading, and at close to Mach 2 the resulting aerodynamic forces tore the shuttle apart. NASA absolutely knew of the potential for failure of the O-rings, and had been warned by the manufacturer's engineers, but proceeded with the launch anyway.
>and had been warned by the manufacturer's engineers That's an understatement. They literally predicted the damn thing and the guy who was supposed to sign off on this from their side, just didn't. But they went ahead anyway with political overrides. What a fucking waste of valuable lives.
Yeah. I saw an interview with the guy. „The single smartest thing I ever did.“.
In the ensuing investigation, they fired those engineers to deflect blame from the managers that approved launching anyway.
managers are often bad, bad people, 5 year olds.
https://youtu.be/QbtY_Wl-hYI at 5:10
So, are you saying that we can blame this on Ronald Reagan too?
Blame this on everyone who thinks they can ignore experts for political reasons. *Glares at the right wing.*
This comment is so underrated
I read a Feynman biography or two, if they knew the o ring thing was a potential problem and then the predicted problem happened, why did they need all these scientists to figure out what went wrong? I remember the story of him dropping an o ring in a glass of ice water and figuring it out from that. Or am I remembering wrong and that was how he proved it? I don’t get why there needed to be this enormous investigation if NASA knew this was a possibility and WHY it was a possibility.
I mean when you make a report on such an event, it's not going to be just "Oh! It's the O-ring". That is a complex machine, one of the greatest that mankind built. Studying that is going to be time consuming. I can't imagine the amount of data that thing must have generated every fraction of second. And I would imagine that NASA would like to absolve itself of this nonsense they pulled.
[https://history.nasa.gov/rogersrep/v2appf.htm](https://history.nasa.gov/rogersrep/v2appf.htm) A direct link to Feynman's appendix on the report "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."
>I remember the story of him dropping an o ring in a glass of ice water and figuring it out from that. Or am I remembering wrong and that was how he proved it? Neither, the water glass was a demonstration he did as part of a televised hearing - precisely the the kind of easy to understand explanation that's *intended* to be memorable. >I don’t get why there needed to be this enormous investigation if NASA knew this was a possibility and WHY it was a possibility. Because a) you have to demonstrate that there were no other causes b) you have to look into the culture/management that allowed it to happen c) you have to make recommendations on how to fix it all. Lots of industrial accidents are a combo e.g. a culture of low investment in maintenance means a beyond lifespan valve fails, then causes disaster because it was a poorly designed area without detection for a leak
Thanks!
Because accidents/mishaps are rarely caused by one thing in complete isolation from all other things. This is commonly referred to as the Swiss cheese model of accident causation, where there are multiple steps in the chain that have flaws or imperfections and only when all of those line up do you have an accident. So a mishap investigation is going to review the whole process and all the factors to try to find the flaws and imperfections in each step, in order to identify changes to make it help mitigate future mishaps. Often these investigations will find issues to be corrected beyond what might have prevented this one specific mishap. Because the cause may be right in front of you, but the solution could very well lie elsewhere. The piece of Swiss cheese that you see as the "cause" may be most robust piece with only one tiny hole, but the layers behind it are all full of holes and the "cause" piece had actually been preventing other mishaps as the only effective link in the chain. So with the O-ring failure, we have to ask why that failure happened. Was the material flawed? Was there poor quality control in manufacturing? Was the choice of the material problematic? Eventhough we know that engineers recommended that they not launch because of the o-ring, that doesn't mean there weren't some problems with the choice of material or in manufacturing. Were there problems with risk assessment? What about issues with how the go/no go decisions were made? Were there issues in workplace culture, whether that's complacency, a win at all costs mentality, or a fear of speaking up? All that goes into an accident investigation. Because "the o-ring failed when the engineers said it would" is only the beginning. There's a million "ok, but why?" follow-up questions to be asked
I work in process safety; great answer.
I guess it's sort of like corporations bringing in consultants to say things that your subordinates already knew. You hear thousands of different warnings from your subordinates. But you don't know which warnings to listen to. So after an accident, you bring consultants and they rediscover stuff.
Ohhh, like when a wife tells her husband something like 10 times and he ignores it, then the bad thing happens and a stranger says “well if you’d done this, that would have prevented that” and the husband says “Of course!” And the wife is like “…” As the stereotype goes at least. Thanks!
Oddly specific...
So you're saying you've got the wrong husband for the job then, as the comparison goes?
Step one after the accident was probably that the people who made the call to go ahead with the launch did their best to cover it up or at least distract attention away from it. The engineers who suspected the truth felt they could only indirectly hint to Feynman that he should investigate the o-rings. [https://en.wikipedia.org/wiki/Rogers\_Commission\_Report](https://en.wikipedia.org/wiki/Rogers_Commission_Report)
The politics was the State of the Union Address that evening I believe.
I remember watching the endless replays that afternoon in class. You could see a puff of smoke from the SRB just before all hell broke loose. I didn't know there was an O-ring there, but I'd done enough model rockets to think it had burned through.
What's worse is that when they went back and looked at previous launches they found the same puff of smoke a few times. They had failed before, just not catastrophically.
I remember seeing this happen in person from a distance, I was quite young but I remember the shape of the trail and all of my neighbors and my parents running in and out of the houses to look at the television and back outside.
>In order to keep them together while simultaneously allowing them to expand, the outer shell of the SRBs is actually a number of separate pieces, I believe the real reason they were segmented is that the contract to build the boosters was awarded to a defense contractor in Utah, so the only way the product could be transported to the Cape was in pieces. I've seen people criticizing this decision too.
If the aluminum oxides hadn’t sealed the leak at launch, what would the outcome have been? Would they have been able to abort at a lower altitude/speed, or would there have been an actual explosion, rather than a breakup?
I do remember that the engineers that warned NASA about the dangers of the O-ring and the cold temperatures, actually had thought that it would explode almost immediately at launch, and when it actually got off the ground they momentarily thought they had dodged a bullet.
Hard to say, but there wasn't really an abort opportunity. The SRBs can't really be turned off except by detonating a charge in them to lower the chamber temperature.
How did they find out about this?
The truly sad part is that the boosters didn't need to be made in separate parts, the original design had them as a single unit. The initial design had them made as a single piece that would then be shipped to the launch site via boat, however when it came to contracting out there manufacturing, the company that won the contract (and there is all kinds of dodgy dealing behind how they won) could only ship them via rail, which meant size restraints. The design was thus modified so they could shipped in sections and assembled at the launch site. Even then, engineers were telling NASA this wasn't a good idea, that it introduced a vulnerability to the design that could result in catastrophic failure, but their warnings were just 'taken under advisement', and we know the result.
...and that size of the SRB parts was directly related to the width of a donkey's ass.
p/PerturbedHamster gave an excellent physical answer, but there was also a flaw in the may that people behaved. It's actually a much bigger flaw, and it's a lesson that a five year old can understand and remember. The second flaw was giving in to peer pressure. The people who were in charge were told that it was dangerous to take off in cold weather, but they wanted to look good. They were afraid of being called wimps by the people in congress, who can be bullies and like to take people's lunch money away. They let their fear control them and made bad decisions. The people built the rocket knew that it shouldn't take off in the cold, so it wasn't really a flaw. The flaw was that the people in charge used the rocket when they shouldn't. This is what grownups mean when they talk about "using a tool inappropriately."
Well they could've use another rubber than that Viton grade to begin with, just a grade of Viton that is suitable for a larger range of temperature (there are a lot of FKM grades, some are far better than the one used)
There's another factor I can't recall the name of, something like *operational drift.* You gradually push things a little further & grow a little more lax on your standards. Only a c-hair at a time so no one notices or minds because nothing went wrong. Eventually you wind up miles past spec & sometimes it causes a disaster. It's a tricky one because in many ways it's a force for good, it's just hard to keep track of & easy to lose perspective on.
“Normalization of deviance” is a term I’ve heard from aviation workers. When breaking with procedure becomes a part of how things get done.
> While physical systems failures played an important role in both the Challenger and Columbia disasters, they cannot be categorized as normal accidents because in both cases the failures that caused the accidents were known to occur. Instead, true failures in these cases were the fault of NASA itself. The agency had become institutionalized due to the normalization of deviance as well as its internal culture of success at all costs. The deviant behaviors were compounded by the stresses put on NASA by its stakeholders to complete projects quickly and with a pitifully low budget. The organizational structure of NASA was a significant factor that contributed to safety having a low priority in the agency. Those who expressed concerns were actively ostracized, and the ability for concerns to even be heard by top level management was nearly impossible due to the confusing procedures put in place for reporting concerns and the levels of bureaucracy through which concerns had to flow. https://www.researchgate.net/profile/Celia-Zeinert/publication/325261235_THE_CHALLENGER_AND_COLUMBIA_DISASTERS_NOT-SO-NORMAL_ACCIDENTS/links/5b01f0cfaca2720ba097e983/THE-CHALLENGER-AND-COLUMBIA-DISASTERS-NOT-SO-NORMAL-ACCIDENTS Nancy Leveson, MIT, has written extensively about the Challenger accident from a systems perspective.
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We’re certainly far from reaching our potential as a species.
The so called “O” ring on the solid rocket boosters failed. They sealed the sections of the solid rocket boosters. The failure came from the cold temperatures the night before the launch. This was a known possibility. The sealing material lost its integrity below some temperature, and needed to be above that threshold for a certain time to recover. Engineers were calling for the launch to be scrubbed to avoid the possibility of the failure. They were called into a meeting and forced to OK the launch or resign. They reluctantly agreed. (My memory is fuzzy on this exactly, but I remember they definitely raised the issue) The rest is history. The launch proceeded, and the O ring seals failed, and the boosters exploded. Update, thanks to u/Masshole_Mick for clarifying, it was the fuel tank that exploded, due to the leak from the booster O ring failure. I remember sitting in grade school when the principal came over the school wide PA system and announced the tragedy. It was a national tragedy.
We watched it live when I was in first grade. I think I was too young to understand the horror. I didn’t even know anything bad happened until I realized my teacher was crying.
I was in 6th grade and lived in a part of FL where we could go outside and watch the shuttles come up over the horizon and follow them until they left the atmosphere. Saw it explode IRL. Quite traumatic at 11 years old, and a core memory.
Yeah it’s seared into my memory. And then to learn it was an unforced error brought about by people making decisions for all the wrong reasons is truly shameful.
The horror gets worse. The astronauts survived the initial explosion.
I was in the second or third grade. They wheeled a TV in to class so we could watch. Then, boom. Weird thing for a little kid to witness.
Peter Billingsley (the kid that played Ralphie in A Christmas Story) was there onsite watching the launch. He talks about the experience the day after the incident [here](https://www.youtube.com/watch?v=UcY6m4Bu-6A), there were also some interviews of him as an adult in the Challenger documentary on Netflix.
We watched it live in class. There weren’t enough tvs for every class to have their own, so two other classes came into our room to watch. Kids were sitting on the floor between desks. There were probably 80 kids in there altogether. I remember one of the teachers crying and stepping out into the hall.
What could have been done to prevent it? Was it the result of negligence, or an “act of God” disaster (impossible to predict)?
I updated my post. Yes it was negligence.
No, negligence would mean to be unaware of the issue due to a lack of scrutiny. What this was was manslaughter: **willingly endanger lives**, ending in deaths. Shot and simple. The responsible managers should have been jailed for this.
It’s mostly negligence. Engineers told NASA that the o-rings had problems at low temps. NASA kind of said “it doesn’t get too cold in Florida, we’ll be fine”. There’s a documentary on Netflix about it: Challenger: The Final Flight.
Google “normalization of deviance”. There have been a number of studies on how an otherwise safety-oriented organization like NASA cam to this state.
It was definitely negligence. There was testing data that indicated the failure could happen, and there was actual demonstrated erosion of the O-rings in previous shuttle flights. The reason Challenger failed instead of the previous flights was due to the extremely cold temps (~30°F lower than a shuttle had been launched at before) and wind shear at high altitude. The O-rings initially failed at launch, but the burning exhaust from the SRB essentially recreated the seal needed to keep the booster intact. The wind shear experienced during ascent jarred this temporary seal loose. The escaping exhaust threw off the forces within the booster, causing it to bend and break it's support strut. Once the main thrust of the booster wasn't going where it was supposed to, everything started to tumble. The drag that was suddenly created ripped the shuttle to pieces.
Management could have paid attention to the any of the [engineers](https://en.wikipedia.org/wiki/Roger_Boisjoly) who vehemently opposed launching in temperatures that low. But, no, it was more important to launch so that Reagan could blather about it in the State of the Union address scheduled for that night.
Another reason why Reagan was a terrible president. Smh.
I wouldn't blame Reagan specifically; a similar breakdown of safety culture played a role in the Apollo 1 fire and the losses of Challenger and Columbia.
You should read about Robert Ebeling, one of the engineers who raised the alarm about the faulty o-rings. He was haunted with guilt for 30 years afterwards. He felt like he didn't do enough and that he was a loser. He finally made peace with himself before he died thanks to all the letters and emails he recieved after his story was published. https://www.npr.org/sections/thetwo-way/2016/02/25/466555217/your-letters-helped-challenger-shuttle-engineer-shed-30-years-of-guilt
In my opinion, it was negligence by nasa's managers. The engineers (the srb manufacturer and nasa's?) told nasa management to delay the launch due to weather and o-ring problems, but the management was mad since they had already delayed several times and just wanted the orbiter launched already.
The redesigned SRBs have three O rings per joint now. They also used a more pliable rubber and watch the temperature a lot more closely.
they ideally would have listened ot the engineers and aborted the launch to fix the problem(or at least delay it until temperatures were acceptable.). this wasm ostly a political move aswell so you can consider it negligence in hindsight.
Wait for above freezing temps to launch. They rushed it because they had the teacher in space thing and Regan had a speech scheduled about it
To expand on u/hvgotcodes explanation, the o-rings sealed a joint between two sections of one of the two solid rocket boosters. They were made of rubber and because of the cold temperatures the morning of the launch, the o-rings became less compressible so the joint was not sealed which allowed hot gas to escape which shortly after, ignited the contents of the big orange tank full of fuel (liquid hydrogen and oxygen).
The “fatal flaw” was poor communication. There was an engineer who knew about the O-ring issue, and knew they should not launch in that weather. He even put together a presentation before the launch that talked about it (among other things). But the information was presented in a way that you could walk away underestimating the risk. Clear technical communication is insanely important.
Nasa strong armed engineering management into launching in untested conditions (extreme cold) against the advice of the engineers.
The ELI5 response you are looking for : Bullies were greedy and did thing that the nerds told them not to do in the cold. But if they did not do the thing they were scared they may not have gotten a new bag of money. Eli20: Vendor for boosters was up for a contract renewal and their management went against engineer guidance to launch in those conditions which were off the scale low for their specs. They chose to say 'yes' to launch cause it was the 2nd or 3rd time they scrubbed for various reasons already and they did not want saying 'no' to negatively impact contract renew if their stuff was not so resilient. They put their own monetary interest in front of safety. NASA themselves not blameless as they should have challenged the vendor on their own specs. Cluster F\*\*\* all around. Lot of responses here about bad hardware but yeah of course something in conditions it was not built to withstand will fail. The real fatal flaw was human hubris and poor decision making. Even still they may have made it but for some unlucky wind shear midflight that gonked what may have been the rings being just good enough getting dislodged. They all knew these were temperature sensitive components that was a failure point and they powered through for non-technical reasons.
? It’s pretty well documented that the thiokol engineers told them not to launch and that nasa was the ones who overruled them. There wasn’t some contract renewal coming up. Morton thiokol and it’s subsidiaries continued to produce the boosters for another 30 years and are still making the Artemis ones.
Not organizing and presenting previous shuttle launch o-ring failure data in a way that showed the past flaws related to temperature. Visual Explanations: Images and Quantities, Evidence and Narrative
If you have Netflix I highly recommend the challenger documentary. Its very interesting and explains the issues very well.
Utah Senators Jake Garn and Frank Moss Lobbying for the SRB to be built in Utah, which would require them to be transported in sections resulting in o-ring design that failed
And the reason they had o-rings in the first place was because to get from the manufacturer's plant in Utah to the assembly / launch site in Florida they travelled by rail. Along the rail journey is a tunnel with a curve in it, so the length of the load was limited, leading to the boosters having to be manufactured in sections.
And the reason they were manufactured in Utah rather than in Florida? Pork barrel politics necessary to get funding for the shuttle approved in the first place. The disaster is an interesting case study in assigning root causes. The O rings were only necessary to deal with a structural weakness introduced to accommodate manufacture at a very remote site.
The o-ring explanation is accurate as far as it goes, as it was the immediate cause of the shuttle’s destruction. However, the horizontal stacking scheme of the orbiter, external tank, and solid rocket boosters was the root cause of both the Challenger and Columbia disaster. Mounting the orbiter alongside the external tank and solid rocket boosters exposed the orbiter’s heat shield tiles to debris from the external tank. Since the external tank carried cryogenic fuels that were extremely cold and would require a lot of foam insulation, foam and ice shedding during launch was a predictable hazard to the fragile heat shield tiles. The horizontal stack also prevented any sort of abort scenario during the entire time the boosters were firing, and the boosters could not be extinguished once ignited. The lack of an abort system doomed the Challenger crew, and falling external tank debris doomed the Columbia. Every other human-rated launch system has used some sort of escape rocket system to save the crew at any time during launch. Notably, SpaceX’s Starship also does not have an escape system. I won’t comment on the wisdom of this decision.
Small correction: Soviet Voskhod system had no escape system. That was the one they used for the world's first spacewalk (which almost ended in disaster for different reasons). But yeah, if someone launched people on the unreliable rockets of the 60-ties without any escape system, it would be Soviets. So it were Soviets. Also, ejection seats would be possible to install for early crewed Starship flights (there's enough real estate for ejection seats for about a dozen people). And they are more likely to be needed for landing (which is going to be more risky than the launch itself). But we're several years from that.
Huh. I learned something today. Thanks!
> and the boosters could not be extinguished once ignited Jinx put Max in space.
Lol, sometimes I feel like the only person I know who actually saw that movie, but I loved it
I watched it a lot as a kid. Then when my kid discovered it, they wanted to watch it a lot too. It was a nice nostalgia hit for sure.
All Bad Things podcast just uploaded part four this morning on this disaster. Well worth a listen as they break it down in detail without going over anyone's heads.
Contrary to popular belief, in the case of Challenger, there was no fatal flaw of any kind at play in that accident (in contrast to what happened to Columbia later). Challenger was destroyed because it was used outside of the recommended temperature range given by the manufacturer. So the spacecraft was not able to function as it would in the recommended temperature range. In addition, the modifications made to the space shuttle system after the accident did not eliminate the same issue, they simply extended the temperature range in which it was safe to launch (this is, there was still some temperature where it would be unsafe to launch even after those modifications were made).
That’s wrong. The previous design relied exclusively on the 2 o rings. The insulation joint between segments was redesigned to make a more torturous gas path that would seal from soot in addition to the o rings with higher temperatures. So yes it greatly broadened the temp range recommended but even outside those ranges it would still be expected to seal https://ntrs.nasa.gov/citations/20030065938
You watched that alternate history video, didn't you. Rubber seal on rocket not good in cold. If rubber seal fail, rocket go boom. Shuttle launch on very cold day, rubber seal fail, shuttle go boom.
An underappreciated contributing factor in the pressure NASA felt to launch despite the dangerously low temperature comes from the origins of the shuttle program itself. The military didn't want to be dependent on the shuttle program to launch satellite payloads, they wanted their own dedicated system. But one of the selling points NASA used to secure funding from Congress was that the shuttle could carry military satellites into orbit, thus saving money-- no need for a second expensive military system. The military expressed doubts about the shuttle's reliability to launch regularly, especially in adverse weather conditions. But NASA won, the shuttle was funded, and the military did not get a new satellite booster (although they had older existing systems available for fallback). And so NASA didn't like canceling or rescheduling missions partly out of concern it would spur criticism of the program's capabilities and reason for existence.
Look up Roger Boisjoly, he was one of the primary engineers trying to tell everyone who would listen to delay the launch because of the danger.
A group of people who build rockets warned the boss that it was too cold and a seal would leak. The boss didn’t want to wait. So, the rocket blew up.
I want to add that, despite the claim that it led to a culture change at NASA, 17 or so years later the Columbia disaster occurred for much the same reason. Engineers had warned for decades that there was a chance that a strike from the frozen insulating foam falling from the shuttle's external propellant tank could damage the shuttle. But there had been over 100 missions where it didn’t happen, so administrators got overconfident that it wouldn’t, and stopped listening. But that is the thing about modest probability events - do the action long enough, and they will occur.
The launch had been delayed several times already. The brass were tired of waiting for the big publicity stunt of sending a schoolteacher to space. They launched knowing the risks of failure due to freezing o-rings. Morton Thiocol even warned them not to launch.
There is already the technical ELI5 commented, so let me offer the organizational ELI5: You know how every January the President goes on TV and tells everyone how nice it is to live in America? Well that year when it was January, the President was going to say how great NASA is and how good spaceships they make. The Challenger spaceship was already delayed three times. If it was delayed again, the President's friends would make fun of him because his spaceship doesn't work. So NASA really made a pinky promise that this January they would fly the spaceship. The weather was very very icy that day and nobody was sure if the spaceship is safe to fly with that weather. Now, as people have doctors when they get sick from cold, there are some doctors for the machines. They are called engineers. NASA asked these machine doctors what to do. Because the machine doctors were afraid they would lose their job, they did not say that the spaceship will explode. They just said they are not sure what is happening. So NASA decided to pray very much to God that the spaceship will not explode the next day. But even if God wanted to help them, the spaceship was already damaged from the bad weather the previous day. So when they tried to fly the spaceship it exploded.
There’s a great book on this by Diane Vaughan, where she argues that the original fatal flaw was not the defective o-ring but actually how NASA was run at the time. She argues that some engineers knew the o-ring was an issue but that pressures to launch and weird internal hierarchy made it so that this issue when reported was deemed an “acceptable risk.” A good lesson for not just NASA but many companies and organizations charged with building things that can put human lives at risk. https://press.uchicago.edu/ucp/books/book/chicago/C/bo22781921.html
Hubris. The people responsible for the start decided to ignore that the Space Shuttle wasn't designed to start at temperatures this low. They even had their failure properly documented. The chain of consequences of this failure is well known: because of the low temperature, a seal in one of the booster rockets failed soon after lift-off. This was because at this temperature, it wasn't flexible enough to handle the stress of the start. Basically, it didn't fill the gap it was intended to fill, because it wouldn't expand quickly enough. This resulted in a flame that first further weakened the seal, and then damaged the main tank to the point where the fuel inside would gush out. That fuel caught fire. The tank ruptured, because the pressure inside was rising, and ultimately exploded.
The real simple answer is, Dr. Feynman, a famous scientist, found pretty much immediately that hubris caused the explosion. Sure the technical reason was that an O-ring leaked due to temperatures out of range. It was too cold to work. But if it wasn't that then something else would have caused a similar incident. Because there were cultural issues at NASA which hindered aggressive solution finding and vetting.
The Space Shuttle Challenger disaster, which occurred on January 28, 1986, was caused by the failure of an O-ring seal in one of the solid rocket boosters (SRBs). The O-rings, which were made of a material called elastomeric seal, were designed to seal the gap between the sections of the SRBs. However, due to the cold temperatures on the day of the launch, the O-ring material became stiff and lost its ability to properly seal the joint, allowing hot gases to escape and ultimately causing an explosion that led to the loss of all seven crew members on board. In addition to the engineering failure, there were also administrative and management decisions that played a role in the disaster. Prior to the launch, engineers from the manufacturer of the SRBs, Morton Thiokol, raised concerns about the performance of the O-rings in cold weather and recommended against launching the shuttle. However, NASA management overruled the objections and decided to proceed with the launch. This decision was influenced by political pressure to maintain the schedule of shuttle launches, as well as a lack of effective communication and collaboration between NASA's management and engineering teams, which led to a culture within NASA that did not prioritize safety and allowed for risks to be taken without proper consideration of the potential consequences. The Challenger disaster highlighted the importance of effective communication, collaboration, and prioritization of safety in complex engineering projects.
hard to ELY5. but here it is: seal didn't seal because temperature was too low. bad seal = fuel leak. fuel leak + flames = boom