Nearly a year after the shuttle Columbia exploded on re-entering the atmosphere, sending NASA into a deep spell of melancholy, Bush is expected to outline a sweeping vision of US space leadership, officials and congressional aides said on Thursday. 

He is expected to propose a new lunar initiative leading to a permanent American presence on the moon and a mission to Mars in the long term, said the sources, who asked to remain unidentified. 

Speaking to reporters with Bush in Florida, White House Press Secretary Scott McClellan said after the Columbia tragedy Bush made clear his desire for US space exploration to continue. 

"The president directed his administration to do a comprehensive review of our space policy, including our priorities and the future direction of the program, and the president will have more to say on it next week," McClellan said, declining to reveal any details in advance. 

Technology exchange

Congressional sources said the administration was also considering setting up a more streamlined hierarchy for guiding the government's wide-ranging space programmes and coordinating its research and development. 

Moon mission will not cause huge
increase in the budget - experts

Under this scenario, there could be more exchanges of technology between NASA and the Defense Department. 

Some members of Congress are worried about ensuring the United States remains the global leader in space exploration. 

"If we do not do it, somebody else will," said Tennessee Rep. Bart Gordon, a ranking Democrat on the House Science
Committee. "The Chinese, the Europeans and the Japanese all have the goal of going to the moon. Certainly we do not want to wake up and see that they have a base there before we do." 

Budget concerns

The new space plan was spearheaded in large part by NASA administrator Sean O'Keefe, who was appointed by Bush to restore credibility to an agency plagued by budget troubles, including billions of dollars in cost overruns at the international space station. 

"If we do not do it, somebody else will.  The Chinese, the Europeans and the Japanese all have the goal of going to the moon. Certainly we do not want to wake up and see that they have a base there before we do." 

Bart Gordon
Democrat on the House Science Committee

Vice President Dick Cheney was also involved in the policy development, along with other senior Bush advisers. The administration was said to see the initiative as an important national security measure and experts said it could lead to new technologies and potential new sources of energy. 

Experts say a moon mission could be done without a significant increase in the budget by spreading the cost over seven to 10 years. 

"You can use the existing infrastructure and be back on the moon in 5 to 10 years with a modest investment. You do not have to double the NASA budget," said Paul Spudis, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Baltimore, Maryland. 

Challenges

Bush's election-year announcement is likely to face challenges from fiscal conservatives and Democrats who want him to focus on domestic issues like education and health care. But the ambitious proposal will strike a chord with some lawmakers. 

Experts said the goal should be to set up a research base on the moon to test technologies that would be useful on a mission to Mars. 

"The idea is to go to Mars. And the way you get to Mars is you go to the moon and you practice three days from home. It is the equivalent of climbing Mount Rainier and preparing for
Mount Everest," said Howard McCurdy, a space-policy expert at American University in Washington.