Mr 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 space flight less than a year after the loss of the space shuttle Columbia and its seven crew.
In a speech delivered at NASA headquarters, Mr Bush unveiled a plan to withdraw the US from the International Space Station by 2010 and retire the shuttle fleet around the same time.
In its place, he called for development of a new Crew Exploratory Vehicle, capable of taking astronauts to the space station and the moon.
Mr 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 programme likely to cost hundreds of billions of dollars.
The space agency arranged a splashy, hi-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 Mr Foale, making his sixth trip into orbit. He said he was also “certain that NASA’s journey is just beginning...”
Mr Bush said the same, delivering a vote of confidence in Sean O’Keefe, the agency’s administrator at the time of the Columbia disaster and in the months since. “It’s time for America to take the next step,” said Mr Bush, 32 years after the Apollo programme last landed men on the moon.
He drew applause from NASA employees when he outlined a timetable for the first human trip to Mars.
Robotic craft would go 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,” Mr Bush said.
“Mankind is drawn to the heavens for the same reason we were once drawn to unknown lands and across the open sea,” Mr Bush said. “We choose to explore space because doing so improves our lives and lifts our national spirit. So let us continue the journey.”
The US space programme drew its first impetus from Cold War competition with the former Soviet Union, and began with a challenge from President John F Kennedy in 1961.
Mr Bush made no mention of Kennedy, but his remarks underscored the change in global politics. “The vision I outline today is a journey, not a race,” he said.