WASHINGTON — President Bush beckoned the nation "forward into the universe" on Wednesday, outlining a costly new effort to return Americans to the moon as early as 2015 and use it as a waystation to Mars and beyond.

Bush said he envisioned "a new foothold on the moon … and new journeys to the world beyond our own," underscoring a renewed commitment to manned spaceflight less than a year after the loss of the space shuttle Columbia and a crew of seven.

In an election-year speech at NASA headquarters a few blocks from the White House, Bush said the United States would complete its obligations to the International Space Station by 2010 and retire the aging space shuttle fleet at about the same time. In its place, he called for development of a new Crew Exploratory Vehicle, capable of carrying astronauts to the space station and the moon.

Bush said early financing would total $12 billion for exploration over the next five years, only $1 billion of it in new funds. That meant that even if he wins a second term in office, his successors in the Oval Office would be responsible for finding the rest of the money for a program likely to run into the hundreds of billions of dollars.

The space agency arranged a splashy, high-tech entrance for the president, who strode to the front of a giant video screen beaming an image of Michael Foale, aboard the space station 240 miles above the earth.

"I know that I'm just one chapter in an ongoing story of discovery," said Foale, making his sixth trip into earth orbit. He said he was also "certain that NASA's journey is just beginning …"

Bush said the same, delivering a vote of confidence in Sean O'Keefe, the agency's administrator at the time of the Columbia breakup and the months since.

"It's time for America to take the next step" in space exploration, said Bush, who spoke 32 years after the American Apollo program last landed astronauts on the moon. He drew applause from NASA employees when he outlined a timetable that would put the first human trip to Mars well into the century. Robotic craft would be sent there first, he said, but exploration wouldn't end there.

"We need to see and examine and touch for ourselves, and only human beings are capable of adapting to the inevitable uncertainties posed by space flight," the president said.

"Mankind is drawn to the heavens for the same reason we were once drawn to unknown lands and across the open sea," Bush said "We choose to explore space because doing so improves our lives and lifts our national spirit. So let us continue the journey."