LAKE BUENA VISTA, Fl. - NASA's efforts to address human spaceflight risk while preparing for future exploration made significant strides this year, but much work remains to be done, space agency risk experts said Tuesday.

NASA risk managers, workers and former astronauts agreed that the space agency has made headway in improving management-level communication across its various centers, though additional time is needed for those changes to filter down to the worker level.

"It doesn't necessarily translate down to our level, below the management level," Sharon Thomas, a technical assistant with the International Space Station (ISS) program integration office at Johnson Space Center (JSC), told a panel of agency managers during NASA's Risk Management Conference 2005. "There's no buy-in at the grassroots level because we may not have had a chance to participate."

Christopher Scolese, chief engineer for NASA and head of its safety-minded Technical Authority, said the space agency has been adjusting its organization to reflect its mandate to return astronauts to the Moon safely by 2018. But answering what that adjustment means to the individual agency worker is vital to the process, he told

Reducing the risks of shuttle and ISS flights to astronauts has been a driving force for NASA since the loss of the Columbia orbiter and its STS-107 crew in 2003. Columbia investigators later cited faults in NASA's internal culture as a contributor in the fatal mishap.

Some evidence of a progress in NASA's bid to change its internal culture surfaced during the space shuttle Discovery's STS-114 mission this summer, which marked the agency's first post-Columbia accident orbiter flight, NASA officials said. During that 14-day mission, orbiter engineers spent days poring over the potential risk of a pair of protruding gap fillers from Discovery's underbelly.

"Prior to STS-107, most people would have said the gap filler was a non-issue," said Steve Poulos, manager of NASA's orbiter project office at JSC, adding that no less than 20 people spoke up during STS-114. "It's asked us to challenge our assumptions, and that's shows us the agency is ready to step up."

But there is still room for improvement.

John Tinsley, mission support division director for NASA's Office of Safety and Mission Assurance, said the space agency should focus as much on the quality of its performance and hardware as it does on safety.

"To me, it's critical for us to build a quality product because we have very complex systems," Tinsley said.