<i>Engineers at Rocketdyne, the manufacturer, estimate the total probability [of catastrophic failure] as 1&#x2F;10,000. Engineers at Marshal estimate it as 1&#x2F;300, while NASA management, to whom these engineers report, claims it is 1&#x2F;100,000. An independent engineer consulting for NASA thought 1 or 2 per 100 a reasonable estimate.</i><p>— <i>Personal observations on the reliability of the Shuttle</i> (Rogers Commission Appendix F) by R.P. Feynman<p>Actual statistics from the life of the shuttle, last flown as STS-135 8 - 21 July, 2011:<p>Total launches 	135<p>Failures 	2<p>Successes 	133<p>Failure rate: 	1.5%