NASA managers insist books aren’t cooked

Hale described his own feelings of shame over the mere appearance of his name as a witness in the report by the Columbia Accident Investigation Board. “I don’t want my name to ever again appear in any accident report,” he stated.

Muratore described the different mathematical approaches to risk assessment that different engineering subcultures used in their own areas of specialization, and how the techniques were being accommodated in the safety reviews. Some approaches used statistical analysis, and some relied on structural analysis and testing, he said. Others took a “systems viewpoint” and ran hundreds of randomized simulations to evaluate the uncertainties surrounding risk assessments.

“When it all came down to rate the risks,” he explained, “there was complete agreement on the level of the risk. Their different ways of assessing risk came up with answers that were essentially the same.”

Both NASA officials struggled for words to put what they called “an extremely complex process” into terms that might be familiar to the general public. “Like many other human activities, this is a messy business,” Hale said. Muratore added that “people are seeing it who aren’t used to looking at it.”

Hale likened the process to the proverb about watching sausages get made. When asked if in fact the “sausage” was now complete, he promised it soon would be. Muratore dismissed doubters with the comparison with “the family member who’s afraid to fly in airplanes.”

Another senior NASA manager with extensive shuttle experience, who exchanged e-mails with MSNBC.com on the condition that his name not be used, called the Times' story “very well done and accurate,” as far as he understood the issues.

He confirmed that the internal safety presentations on the consequences of debris impact on the orbiter’s wings had concluded that the first tank did not meet the higher standards that considered the potential damage to the shuttle's brittle leading-edge panels. That first tank was prepared for flight using "largely heritage processes, with modifications to the high-risk areas," he noted.

At the same time, he continued, the substantial safety risk is a result of the overall shuttle design, not of any detailed mechanical adjustments that can reasonably be made.

“I think it is not unwise to return to flight,” he said in the e-mail, while adding that better safety standards would have to be built into the designs of follow-on human space vehicles.

As Muratore explained, different levels of reliability can justifiably be used for contingency events of differing original probability. For the issue of damage to the shuttle’s thermal protection system, the hazard level is eased by a reduction in the probability of debris coming off at launch — and by the equally significant development of recovery strategies, such as seeking “safe haven” aboard the space station, that would be used if damage does occur.

James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer.

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