US president George Bush looked ahead to "new journeys to the worlds beyond our own" as he unveiled a plan to send astronauts to the moon, Mars and beyond, on missions sure to cost hundreds of billions of dollars and stretch the bounds of technology.
The president called a manned lunar landing as early as 2015 in his election-year initiative yesterday - the boldest space goals since John F Kennedy laid the groundwork for the Apollo programme that landed Americans on the moon in 1969.
Intended to inject new life into a space programme shattered by last year's loss of the Columbia shuttle and its crew of seven, Bush's proposal faces tough questions in Congress. But many Democrats say the administration should take care of problems at home before setting its sights on costly space initiatives, particularly in the face of budget deficits of about £275 billion.
Some scientists say it would be more efficient and less expensive to use robotic spacecraft instead of manned missions. Bush's father proposed a Mars mission in 1989, but it collapsed when cost estimates hit £220-£275 billion.
In a speech at Nasa's Washington headquarters, Bush laid out a timetable for robotic missions to the moon no later than 2008, the first manned flight of a new spacecraft by 2014 and a manned lunar mission as early as 2015 and no later than 2020.
The president did not set a deadline for reaching Mars, and Nasa director Sean O'Keefe said later said the timing of the mission would depend on the results of studies on the effects of space travel on humans.
Bush said the moon, with a gravity pull one-sixth that of Earth, could be the launching pad for "human missions to Mars and to worlds beyond". He said his goal was to "extend a human presence across our solar system".
In vivid terms, Bush portrayed America's space programme - with its three shuttles grounded by the Columbia accident - as at a standstill. "In the past 30 years, no human being has set foot on another world or ventured farther up into space than 386 miles, roughly the distance from Washington DC to Boston, Massachusetts," Bush said.
"It is time for America to take the next steps."