NASA's work force is graying and the agency lacks a long-term plan for luring qualified workers to help send astronauts to the moon and Mars, a National Research Council report says.

"NASA doesn't have a lot of people leaving, so what's been happening is they're aging in place," said MIT aeronautics professor Daniel Hastings, who co-chaired the panel of aerospace industry experts who wrote the report.

The space agency has been too focused on short-term labor problems, such as what to do with some 900 employees whose work is ending along with the soon-to-be-retired space shuttle, the experts wrote. And there has not been enough attention on the type of skills needed in the future and the aging of the work force, they said.

"They actually don't have a strategy," said Hastings. "They're too focused on the short term."

NASA requested the report last year from the research council, a nonprofit organization that is part of the National Academies of Science, which offer policy advice under congressional charter. A final version of the report will come out in early 2007.

NASA spokesman Doc Mirelson said the space agency would reserve commenting on the interim report until making a formal response Monday at a meeting with the panel.

The report noted that NASA doesn't regularly hire workers straight out of college because of the extensive training needed and prefers engineers and scientists with some experience.

"They like to hire people in their 30s ... at a little more mature stage of their careers," said panelist John Douglass, president and CEO of the Aerospace Industries Association. "Growing people straight out of college is kind of what industry does."

The report urges the agency to use personnel exchanges with academia and the private sector to bring in new blood rather than training recent graduates. Many young engineers and scientists don't view NASA as an exciting place to work, the report said.

NASA's 18,400 workers, along with the tens of thousands of contract employees, face the end of the space shuttle program in 2010 and the development of next-generation vehicles that will allow astronauts to go back to the moon and eventually explore Mars. The two projects require different skill sets, forcing NASA to keep space shuttle workers in place, while at the same time designing, building and testing new vehicles.

The lack of major turnover at the space agency has added to the aging of the work force and the lack of younger employees. NASA only hired 411 new engineers in 2005, or about 4 percent of the 10,700 engineers at the agency. Only a quarter of NASA's engineers and scientists are under age 40, and by 2011 the agency predicts that close to half of its scientists and more than a quarter of its engineers will be eligible for retirement, the report noted.

The panel found no evidence of a shortage of aerospace scientists and engineers as had been forecast for the industry but agreed that NASA was having trouble finding some workers, such as system engineers and project managers.

"I thought they would have jumped on this a little sooner," Ray Haynes, an official at Northrop Grumman Space Technology who served on the panel, said of the agency's lack of a work force strategy. "Better later than not at all."