"Our task is to align headquarters to ... promote synergy across the agency and support the long-term exploration vision in a way that is sustainable and affordable," O'Keefe said in a statement.

Last week, a special commission of experts said the National Aeronautics and Space Administration needed to become a "leaner, more focused agency."

The changes will also help "create a structure that affixes clear authority and accountability," the statement said.

The rejigging is part of NASA's implementation of recommendations by a panel that investigated last year's Columbia shuttle disaster.

In a report issued seven months after the accident, the Columbia Accident Investigation Board detailed NASA's errors and the erosion of safety procedures since the shuttle Challenger exploded on takeoff in 1986.

Bush, who is running for a second term in the November 2 presidential election, announced in January his desire to send people back to the moon as early as 2015, followed by manned missions to Mars and other planets in the solar system.

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