The $104 billion program to return astronauts to the moon by 2018 was unveiled by the administrator of the NASA space agency, Michael Griffin, in Washington on 19 September.
The move may be seen as an attempt to stay in the space race. Both Russia and China are capable of human spaceflight, and Beijing has also set its sights on the moon, with plans to land an unmanned probe by 2010. Other countries are looking to develop their space programs as well.
Griffin said the prospect of returning to the moon will "build confidence that astronauts can venture still farther into space and stay for longer periods." President George W. Bush has already said the moon trips are a precursor to voyages to Mars and possibly other planets in the solar system.
In Paris, a spokesman for the European Space Agency, Franco Bonacina, said the new American space venture will benefit the world space community. Bonacina notes the U.S. has already offered international cooperation with other space agencies.
"The door is open to international cooperation when [astronauts] are on the moon. As President Bush has already said, international partners will be invited to join in, and we have already had a good experience of international cooperation on the [present] international space station project. I think we will certainly take this opportunty and do something together," Bonacina said.
In Washington, NASA administrator Griffin described the new venture as a necessary "investment" for his agency. The moon announcement comes at a time when the space agency is under pressure to justify its big budget -- especially in the wake of costly natural disasters like Hurricane Katrina, whose damage may cost as much as $200 billion to repair.
Griffin said crises like Katrina should not mean the end of NASA's long-term space projects.
"The space program is a long-term investment in our future. We must deal with our short-term problems without sacrificing our long-term investments in our future," Griffin said.
NASA must also deal with safety concerns over its ageing fleet of space shuttles following the difficulties of the shuttle "Discovery" in August, which lost pieces of its heat shield after take-off despite an extensive research and prevention program. The previous shuttle voyage, that of the "Columbia," ended in disaster in 2003 for a similar reason.
NASA's budget for 2006 alone is $16 billion. This funding is despite the current financial pressure on the U.S. budget, which has been depleted by not only Katrina but the war in Iraq, which runs at over $5 billion a month.
Griffin defended the cost of the moon project, saying it will not require an increase in NASA's budget. He also suggested that it would be irrational to cut spending on space because of transient factors like Katrina.
"When we have a hurricane, we don't cancel the Air Force, we don't cancel the Navy and we are not going to cancel NASA," Griffin said.
The new missions to the moon will be preceded by unmanned robot trips between 2008 and 2011.
The methodology for the new moon missions will outwardly resemble that of the original "Apollo" lunar missions betweeen 1969 and 1972.
The astronauts will go into space aboard a conventional rocket, from which their capsule will detach. They will then meet up with a lunar landing craft, sent up separately. The crew will journey to the surface of the moon in the lander, the bottom section of which will stay on the moon as the basis for a permanent base.
Returning to the orbiting capsule in the upper part of the lander, the crew will be able to reenter the earth's atmosphere and make a soft landing by parachute in the "old-fashioned way" of the Apollo missions.
The use of pre-shuttle techniques may look like a backward step, but European Space Agency spokesman Bonacina says that actually isn't the case.
"The physics of our world, and the ways of putting things into space, has not changed, so the machinery looks much the same, even if the content is much, much more sophisticated," Bonacina said.
The moon lander will normally carry four people, who will initially remain on the moon for a week.