Departing NASA Administrator Sean O'Keefe says the space agency's much-criticized safety culture has greatly improved since the Columbia disaster in 2003 — a claim disputed by a retiring astronaut.

It's difficult for a big bureaucracy like NASA to change its ways, says John Young. He says it will probably be a long time before the space agency alters the way it thinks and behaves.

"I was in the astronaut office the other day and I asked them how many people thought NASA had changed its culture and nobody raised their hand," Young told the Associated Press. "There were about 100 people there, so that's how they feel right now."

"It's a long-term effort," concedes O'Keefe in an interview with the Houston Chronicle. "It's not something that's going to happen overnight. But the current progress has been quite remarkable."

According to O'Keefe, an ongoing analysis by a California consulting firm reinforces how NASA's culture is changing. Behavioral Science Technology reported in August that the space agency's four major hubs — including Johnson Space Center in Houston — showed signs of improvement in the way managers and workers discuss safety issues.

But BST's report cautioned that the impact of the reforms hadn't reached six other NASA facilities and the agency's many contractors.

"There's an awful lot structurally that's been put in motion on this whole culture change agenda," O'Keefe says.

"We've been doing everything we know how to — posting it on the Web site, doing briefings, everything," O'Keefe says.

Young, at 74 the nation's longest-serving astronaut and the ninth man to walk on the moon, offers a different view: NASA and the nation should just accept the failure rate of 1-in-57 shuttle flights, he says, stressing that space exploration is well worth the risk.

Like others at NASA, Young regrets not pushing engineers harder for answers after the Columbia was damaged by a blow from a chunk of foam. He questioned an engineer three days into Columbia's doomed flight and was assured, "Don't worry. There's nothing. It didn't hit it."