Remembering the Challenger
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Did they ever recover the bodies? Would the autopsy have shown death by asphyxiation as opposed to blunt force trauma?
I remember the day like it was yesterday. I was at my desk as a Thiokol engineer looking at the computer screen working on my computer code for leaking joint pressurization. (My code did not include O-ring erosion, but I discussed methods of solution with another person in my cubicle that did have oring erosion.) I thought I heard someone come over to one of the nearby manager's offices and say that the shuttle had blown up. I had not gone upstairs to watch the launch, because I had seen so many. To this day I am not sure that I heard someone say this in the background. Anyways, at some point I looked around my cubicle and none of my co-workers were around. I got up and walked down the aisle and did not see any of my co-workers in the adjacent cubicles. I went over to another aisle and found a bunch of engineers in a cubicle all gathered around a radio listening intently and quietly. I listened to the news report and slowly the terrible realization dawned on me.
boatgeek
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I was out of country at the time, so only heard it in words later, so it wasn't the immediate impact. One of the teachers at my former elementary school was selected for the program. My memory was that she was McAuliffe's backup, but I don't know if that's true.
I took an engineering ethics webinar on the Challenger disaster a year or two ago. I was appalled by how much was known about SRB O-ring leaks in cold temperatures and management's decision to launch anyway. One interesting thing was that partial blame came to engineers saying "Look, there's an elevated risk of gas leakage" and not "This could destroy the shuttle." It's easier to ignore the former even though it means the same thing to the engineer. Of course, most came down to management telling people to put management hats on and not engineering hats as well as perceived political pressure (wanting a flight to talk about in the State of the Union address). I don't think that pressure came from the Oval Office, but NASA management felt pressure to fly, whether that was from the White House staff or internal to NASA.
I took an engineering ethics webinar on the Challenger disaster a year or two ago. I was appalled by how much was known about SRB O-ring leaks in cold temperatures and management's decision to launch anyway. One interesting thing was that partial blame came to engineers saying "Look, there's an elevated risk of gas leakage" and not "This could destroy the shuttle." It's easier to ignore the former even though it means the same thing to the engineer. Of course, most came down to management telling people to put management hats on and not engineering hats as well as perceived political pressure (wanting a flight to talk about in the State of the Union address). I don't think that pressure came from the Oval Office, but NASA management felt pressure to fly, whether that was from the White House staff or internal to NASA.
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I haven't watched the above video, but if doesn't mention the polysulfide putty blow holes it is typical with the public's perception of the problem. The cold effect on the o-rings was very important, but equally important were the putty blow holes. Perhaps, the blow holes were even more important. We discussed this several years ago on TRF after the Feynman TV movie. Dr. Feynman made the o-ring resiliency problem famous with his famous ice water o-ring demonstration during the Rogers Commission. However, it didn't begin to mention the blow hole problem. During the $400 million recovery effort the putty was completely eliminated from the design along with cold o-rings being addressed.
Wow so you were there and know better than most of us. I find it amazing how many industry people use this forum.
Thanks for your input.
Thank you. There were several issues and even though the nozzle-to-case design looked very different from the field joint, it had the same issues. Off the top of my head the main issues were these:
1) Joint (structural) rotation. That is, when the motor was pressurized in the first second, the steel cases tended to rotate a small amount (perhaps on the order of 40 mils) about the joint and the steel on the opposite could move away from the o-ring leaving a gap through which extremely hot gas could flow. The remedy for the field joint was to put in an additional steel thumb (it looked like a tang) to stop the joint rotation. The remedy for the nozzle-to-case joint was to put in additional bolts.
2) The primary oring was moved (forward) in the wrong direction during the leak check test, so that the primary oring was not at the back of the oring groove. The remedy was to put in another oring and oring groove ahead of the primary and another leak check port. The first leak check through the old leak check port could push the oring in the wrong direction, but when the second leak check was performed through the new leak check port, it would push the primary oring to the back of its groove. Thus, the primary and secondary oring ended up in the correct direction. This was done for both the field and nozzle joint. The new oring was called a "barrier oring" and was not considered a true seal, because it could be pushed in the wrong direction.
3) The leaks through the polysulfide putty were eliminated by removing the putty from the design altogether and designing a J-joint molded rubber insulation flap that would be pushed against an adjacent surface to form a seal upon motor pressurization where the putty use to be. There was a weak adhesive put on the J-joint surface so that it would weakly stick to the other side upon assembly. The steel capture feature (steel thumb that looked like a new tang) had an interference fit with it is mating surface, so that if there was ever a gas leak through the J-seal, the gas would flow through the interference fit on its way to the barrier oring. This interference fit did a good job of slowing the flow and quenching the hot gas. (In practice the interference fit never played a significant role, because everything else worked so well.) (There was a rubber volume-filler placed after the secondary oring to reduce the free volume for gas filling, but this feature was not considered to be significant by some engineers.)
4) Exterior electric joint heaters were put around the joints to keep the orings warm.
These are the major re-design features that I remember off the top of my head. They are the technical aspects of the recovery effort. As someone mentioned earlier in this thread there were the management considerations on both the Thiokol and NASA ends, which played out as high drama the night before the launch. I like Allan McDonald's book, "Truth, Lies, and O-rings". Years later I was at a social event and I sat down next to Allan McDonald for dinner without recognizing him. It was an extremely fortunate event for me. He told me how he had kept extensive notes of all things that happened and that he was in the process of writing a book. In 2010 I went to a lecture he had locally and got an autographed copy.
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SpaceManMat
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Read the wiki link and also another about the abort scenarios. What I find hard to believe is that they were violating so many of their mission rules and got away with it for so long. On top of that after the accident they still did not come up with a way to deal with a SRB failure. It's simply a case of ride it out, a strategy that is almost always doomed to fail.
MClark
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I was working and driving the truck, listening to the launch on the radio. When it failed I was going by a pawn shop and turned in. Pawn shops always have a TV on. Inside the were freaking out, yelling, not knowing what to do. I watched for a few minutes, drove to the shop and went home.
Columbia struck way closer to home for me. I had looked at the ground track, estimated the altitude and determined we should be able to see it. As we watched, way off several hundred miles, the bright dot looked variable. I just thought it was clouds. Cool, saw it, go back to bed. Half hour later Robin calls and tells me what happened.
I never tried to watch again.
M
Columbia struck way closer to home for me. I had looked at the ground track, estimated the altitude and determined we should be able to see it. As we watched, way off several hundred miles, the bright dot looked variable. I just thought it was clouds. Cool, saw it, go back to bed. Half hour later Robin calls and tells me what happened.
I never tried to watch again.
M
JStarStar
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With no escape/ejection system, it was ordained from day one that if anything ever went wrong from SRB ignition to jettison, the crew was dead.
There was no "abort scenario" which would allow the crew to get off an exploding/disintegrating SRB/ET package, do a barrel roll or loop de loop with the Orbiter, and come down in any kind of escapable ditch. The orbiter was not a T-38 trainer designed to do aerobatics.
I knew that the minute I saw the preliminary design drawings in 1972-73.
The idea post-Challenger that the crew would ever be able to get out of their seats in a plunging orbiter and get to a hatch to bail out was preposterous.
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ericclinedinst
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Here's a movie that I don't think has been mentioned on this thread. [video=youtube;DT7Yx5kxYco]https://www.youtube.com/watch?v=DT7Yx5kxYco[/video] Definitely worth checking out.
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Did you happen to know Bob Ebeling?
I was young...7. My parents would tape the launches for me and I'd watch when I came home from school. I remember they were quite sad, and told me the launch did not go well, or something to that effect. Credit to them for letting me watch it. It's one of the events in my life that always makes me stop and look back over things one last time, and consider if I think something will work, or if I just want it to.
Wow, assuming that movie is accurate it certainly paints a a much more sinister picture than I originally had. I knew there were failures at both the mechanical level and with management, but this goes way beyond that. I am surprised that NASA wasn't taken to task, or maybe they were? I now the SRB manufacturer paid claims to at least some family members of the Challenger crew.
terryg
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An interesting video about the accident. It appears that aluminum slag from the propellant temporally blocked the joint until dislodged by strong wind shear encountered later in the flight.
[video=youtube;INIUciUNwok]https://www.youtube.com/watch?v=INIUciUNwok[/video]
[video=youtube;INIUciUNwok]https://www.youtube.com/watch?v=INIUciUNwok[/video]
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Yes, some Thiokol engineers thought that Challanger would blow up upon ignition and were surprised and relieved that it didn't.
https://www.npr.org/sections/thetwo...ster-challenger-engineer-still-blames-himself
nute
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I mention the Feynman movie in post #36.
The video has a lot of good stuff especially about the sequence and timing of events in accident. The animation of the "joint rotation" is good, but the diagram shows nothing about the insulation above the joint. It might lead a person to think that propellant was cast all the way to the steel case. In reality the insulation was heavier above the tang (the part that fits into the clevis) and clevis(part that looks like a tuning fork in cross-section). When the two segments were mated together, putty strips were laid down between the two opposing insulation faces. The forward surface of the propellant surface was completely inhibited.
I did not know Bob Ebeling, but I have heard of him. About 5 years ago I went to a static firing shortly after I retired. I met 2 ladies there. One was Bob Ebeling's daughter and the other was his wife. Bob EBeling was very upset with the outcome of events and stopped attending static test firings long ago.
Coincidentally this was just published https://www.npr.org/sections/thetwo...ster-challenger-engineer-still-blames-himself
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These Challenger anniversaries must be awful for him. We mourn the loss of the astronauts but we must also mourn the effect this disaster have on some of the still living.
