NASA Is Said to Loosen Risk Standards for Shuttle

NASA officials have loosened the standards for what constitutes an acceptable risk of damage from the kind of debris that led to the disintegration of the shuttle Columbia as it was returning from space two years ago, internal documents show.
The move has set off a 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.
Experts who have seen the documents say they do not suggest that the shuttle Discovery - scheduled to lift off from Cape Canaveral, Fla., on May 22 - is unsafe, but a small but forceful minority say they worry that NASA is repeating a practice that contributed to the Columbia disaster: playing down risks to continue sending humans into space.
The documents were given to The New York Times by several NASA employees, who asked not to be named, saying they feared retribution.