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Engineers at Rocketdyne, the manufacturer, estimate the total probability [of catastrophic failure] as 1/10,000. Engineers at Marshal estimate it as 1/300, while NASA management, to whom these engineers report, claims it is 1/100,000. An independent engineer consulting for NASA thought 1 or 2 per 100 a reasonable estimate.

— Personal observations on the reliability of the Shuttle (Rogers Commission Appendix F) by R.P. Feynman

Actual statistics from the life of the shuttle, last flown as STS-135 8 - 21 July, 2011:

Total launches 135

Failures 2

Successes 133

Failure rate: 1.5%



Presumably, those estimates are just for the Space Shuttle Main Engines (SSME/RS-25), give that's what Rocketdyne was manufacturing and propulsion is one of Marshall Spaceflight Center's fortes.


> Presumably, those estimates are just for the Space Shuttle Main Engines (SSME/RS-25)

If so, the risk for the entire system (shuttle) should be higher, not lower.


Yep.

Edit: To be clear, I wasn't saying it was lower.


> I wasn't saying it was lower.

Sorry, I didn't mean to refer to you; I should have been more clear. I was referring to NASA's or anyone's estimates for the shuttle.


Sometimes if you want an accurate answer you have to ask someone whose career/income doesn't depend on the answer.




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