Washington Post Engineers' E-mails Warned NASA Downplaying Shuttle Problems

"In one e-mail sent three days before the shuttle's Feb. 1 disintegration as it hit the Earth's atmosphere, a Langley engineer complained that those managing Columbia's flight had chosen not to make simple studies to clarify landing risks and were treating such information "like the plague."

The engineer, Robert Daugherty, also said he understood NASA engineers at flight headquarters in Texas had privately estimated its safety during landing was "survivable but marginal.""

redux [02.01.03]
The New York Times Speed Makes Space Flight Very Risky, Experts Say
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"A success rate of about 95 percent is more typical of the trade, Dr. Postol said. With two catastrophic failures in 113 flights, for a 98.2 percent success rate, the shuttle program is not looking much different -- for sound physical reasons, he said.

"Capt. Bill Readdy, associate administrator for space flight and a former astronaut, said at a news conference yesterday afternoon: "Today was a very stark reminder that this is a very risky endeavor, pushing back the frontiers in outer space. And after 113 flights, unfortunately, people have a tendency to look at it as something that is more or less routine. Well I can assure you it is not.""

The Guardian Unlimited Nasa chiefs 'repeatedly ignored' safety warnings

"Fears of a catastrophic shuttle accident were raised last summer with the White House by a former Nasa engineer who pleaded for a presidential order to halt all further shuttle flights until safety issues had been addressed.

In a letter to the White House, Don Nelson, who served with Nasa for 36 years until he retired in 1999, wrote to President George W. Bush warning that his 'intervention' was necessary to 'prevent another catastrophic space shuttle accident'."

Richard Feynman Personal observations on the reliability of the Shuttle

"If a reasonable launch schedule is to be maintained, engineering often cannot be done fast enough to keep up with the expectations of originally conservative certification criteria designed to guarantee a very safe vehicle. In these situations, subtly, and often with apparently logical arguments, the criteria are altered so that flights may still be certified in time. They therefore fly in a relatively unsafe condition, with a chance of failure of the order of a percent (it is difficult to be more accurate).

Official management, on the other hand, claims to believe the probability of failure is a thousand times less. One reason for this may be an attempt to assure the government of NASA perfection and success in order to ensure the supply of funds. The other may be that they sincerely believed it to be true, demonstrating an almost incredible lack of communication between themselves and their working engineers."

redux [02.06.03]
Reason The Limits of Complexity

"The week has brought a painful reminder of the limits of complex systems and human fallibility."

"So there is the crux of the matter, across shuttle, software, and oil truck. At what point does complexity make a system more prone to break, rather than less? Can added cost always justify greater reliability? How do we know when the risk of something going wrong is too great?

If in answering such questions you require or assume perfection, something might go very wrong indeed."

Houston Chronicle 10 years after Challenger, NASA feels shuttle safety never better

"In 1988, SAIC evaluated the launch risk for NASA relying primarily on factors applicable during the shuttle's pre-Challenger era, including the flawed solid rocket booster. The assessment produced a range of risk with a mean probability of a shuttle loss at one in every 78 launches.

The risk mean for a shuttle loss during the liftoff improved to one in every 248 ascents when the assessment was repeated this year and the shuttle's post-Challenger actual track record was factored into the calculations.