Shuttle managers deny the allegation, saying they are adjusting calculations.
NEW YORK (AP) -- Internal NASA documents obtained by a newspaper suggest that the agency is playing down the dangers posed by shuttle debris so it can continue to send astronauts into space. But space agency officials denied Friday that safety standards are being loosened.
The New York Times reported Friday that the documents by engineers and managers for the space agency show at least three changes in the statistical methods used in assessing the risks of debris like ice and insulating foam striking a shuttle during launching.
One presentation said lesser standards must be used to support accepting the risks of flight "because we cannot meet" the traditional standards, according to the newspaper.
The Times said there is debate within the agency about whether the changes are a reasonable reassessment of the hazards of flight or whether they jettison long-established rules to justify getting back to space quickly.
But NASA officials said in a telephone news conference Friday evening that while engineers have differed in their mathematical approach to analyzing the threat of launch debris, in the end they all agreed on the risk levels. The discussion was open and all opinions were heard, they said.
More analysis is needed before Discovery can lift off, as early as May 22, the officials noted.
A suitcase-size piece of fuel-tank foam insulation was blamed for the disintegration of the shuttle Columbia as it was returning from space in February 2003.
Earlier this month, shuttle systems engineering manager John Muratore openly acknowledged that even marshmallow-size pieces of insulating foam from the fuel tank could doom the space shuttle under the worst circumstances. He told reporters it is a risk NASA and the nation must accept for flights to resume anytime soon, and that it would take a total redesign of the tank to completely eliminate foam loss.
Muratore said Friday evening that none of the risk assessment numbers have changed since his comments in early April -- in fact, he said, they have not changed in nearly a year. He stressed that he does not view any changes in risk assessment as a relaxation of safety.
"What we're doing is increasing the accuracy of the solution," Muratore said.
Added shuttle program manager Wayne Hale: "We are not moving the standard, we're sharpening the pencil on how we do our calculations and how we make the assumptions."
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