US President George Bush proposed today to develop a new spacecraft to carry Americans back to the moon by 2015, and to establish a long-term base there as an eventual springboard to Mars and beyond.
Mr Bush would withdraw the US from the International Space Station by 2010 and retire the space shuttle fleet at about the same time.
Details of his proposal were released by the White House in advance of a speech by the president at NASA headquarters.
An extended human presence on the moon "will enable astronauts to develop new technologies and harness the moon's abundant resources to allow manned exploration of more challenging environments," the White House said in a statement.
"The experience and knowledge gained on the moon will serve as a foundation for human missions beyond the moon, beginning with Mars," the statement said. The moon has one-sixth the gravitational field of Earth, so moon-based aircraft could launch from there more cheaply.
"The president's vision affirms our nation's commitment to manned space exploration," the White House statement said. "It gives NASA a new focus and clear objectives. It will be affordable and sustainable while maintaining the highest levels of safety."
AP