President Bush signed into law a $20.2 billion NASA authorization bill, a measure that NASA Administrator Michael Griffin welcomed because it endorses the long-term goal of moving beyond low Earth orbit.

"I’m grateful to the president for his signature on the" measure, Griffin said. "The major provisions of this authorization bill affirm [congressional] support for the broad goals of the president’s space exploration policy, including the return of American astronauts to the moon, exploration of Mars and other destinations."

Since the end of the Apollo missions in the 1970s, the U.S. space program has gone no farther than low Earth orbit. At first, after Apollo lunar missions ended, NASA had no vehicle for manned missions to space, and then, in the 1980s, began using the space shuttle fleet to haul immense structural components into orbit to build the $100 billion International Space Station.

NASA now is approaching another point where it will lack any manned space vehicle, when shuttles retire as Bush ordered by October 2010. For half a decade, the United States will have to depend on the Russians to haul U.S. astronauts to space on Soyuz spacecraft, until the first manned flight of the next-generation American Orion-Ares spacecraft system in 2015.

While the first Orion missions will be to the space station, going only to low Earth orbit, Griffin has said he wants to see Americans move beyond that, going to explore the moon and Mars.

The first lunar mission won’t occur until around 2020, and by that time Chinese taikonauts may be on the dusty lunar surface, planting their flags there.

In the 2020s, a permanent manned U.S. outpost on the moon is envisioned. A mission to Mars isn’t expected until the 2030s.