Saturday, March 19, 2011

Challenger explosion

The Challenger explosion -- I recall something about the joints on the solid fuel rockets being mounted upside down? (So that liquid could seep in, which led to the failure of the o-rings.) Am I remembering correctly? Anyone? I've tried googling this for about the last hour and I'm not finding anything.


Mike G. said...

Grrr, re-commenting to get followup comments.

Jon said...

You're probably thinking of the problems with the aft SRB field joint identified in the Rogers Commission report, see e.g.

Dan Moran said...

Blogspot's being a little weird. This was Mike G's original comment, which appears to have vanished:


3. Evidence examined in the review of Space Shuttle material,
manufacturing, assembly, quality control, and processing on
non-conformance reports found no flight hardware shipped to the launch
site that fell outside the limits of Shuttle design specifications.

Mike G. said...

Thanks Dan. There was another paragraph to that, I think, something like:

"If I remember correctly, the cold made the o-rings brittle and let the gas blow by, burning through the external tank."

Pretty well "What Jon Said"...

Dan Moran said...

Yes, I understand the failure mechanism of the o-rings. Just trying to get a sense of whether the rocket joints being upside down (I'm almost certain about this, just can't find a reference) is still thought to have contributed to the o-ring failure.

Mike G. said...

The "found no flight hardware shipped to the launch
site that fell outside the limits of Shuttle design specifications" part of the snippet I posted seems to rule that out.

Unless you think it was designed upside-down?

Dan Moran said...

"There is a possibility that there was water in the clevis of the STS 51-L joints since water was found in the STS-9 joints during a destack operation after exposure to less rainfall than STS 51-L. At time of launch, it was cold enough that water present in the joint would freeze. Tests show that ice in the joint can inhibit proper secondary seal performance."

Pretty sure this is what I'm recalling. It's in the link you & Jon posted.

Mike G. said...

There were design flaws. But I don't think "upside down" really describes them. That chapter of the report is a good easy read.


In view of the findings, the Commission concluded that the cause of
the Challenger accident was the failure of the pressure seal in the
aft field joint of the right Solid Rocket Booster. The failure was
due to a faulty design unacceptably sensitive to a number of factors.
These factors were the effects of temperature, physical dimensions,
the character of materials, the effects of reusability, processing and
the reaction of the joint to dynamic loading.

Mike G. said...

Ooops, our posts crossed each other. :)

mkr said...

Check out Tufte's analysis in Visual Explanations. If the data had been presented to the decision makers correctly, the Challenger never would have been launched that day.

W. Craig Trader said...
This comment has been removed by the author.
W. Craig Trader said...

Frankly, the best part of the Rogers Commission report is Richard Feynman's appendix F:

What really killed Challenger was the way that NASA managed the Shuttle program. And 17 years later, the same management style killed Columbia.

Dana said...

Regarding Tufte's analysis in Visual Explanations, that was used in a National Security Decision-Making course I took at Naval War College in '05 (the class is also known as "how organizations composed of really smart people do really dumb things"). How you present data to people is critically important.