"The real objective is to explore," O'Keefe told NBC television's "Today" show. "It's not about a destination; it's about looking at any number of different capabilities or different things we may want to explore in the solar system."

O'Keefe downplayed projections that the cost for a planned new mission to the moon, expected to be announced by Bush on Wednesday, would be astronomical -- around 750 billion dollars, according to some experts cited by NBC.

"Oh, positively not," he said. "We're spending less than one percent of the federal budget on the science and technology that NASA employs for exploration objectives, and that won't change."

Bush was to deliver a speech Wednesday setting "new horizons" for the US space program, aiming to send manned missions to the moon -- and eventually beyond.

"It's about the capacity, the capability, the technology to get anywhere, and that's what he's (Bush is) going to outline today, is that broader direction for exploration goals," O'Keefe said.

He added that the focus is "a new direction, a renewed direction to explore and discover, to use technologies and science to really expand for our benefit across the board."

SPACE.WIRE