NASA released an estimate on Monday that it will cost 104 billion US dollars to return astronauts to the moon by 2018.
NASA Administrator Michael Griffin said he is not seeking extra money and stressed that the space agency will live within its future budgets to achieve this goal.
He also dismissed suggestions that reconstruction of the Gulf Coast in the wake of Hurricane Katrina might derail the program.
(2a/soundbite/0920 Michael)
"We're talking about returning to the moon in 2018. There will be a lot more hurricanes and a lot more other natural disasters to befall the United States and the world in that time, I hope none worse than Katrina. When we have a hurricane, we don't cancel the Air Force. We don't cancel the Navy. And we're not going to cancel NASA."
The 104 billion US dollar price tag, spread over 13 years, represents 55 percent of what the Apollo moon-landing program cost in real terms. Apollo spanned eight years.
The new lunar lander would carry double the number of people to the surface of the moon - four - and allow them to stay up to a week, or twice as long. It would also haul considerably more cargo, much of which would be left on the moon for future crews.
If all goes well, the first crew would set off for the moon by 2018 - or 2020 at the latest, President Bush's target year.