Nasa awards US$6.8b to Boeing and SpaceX for space shuttle replacements

The United States took its first major step to returning to manned space flight as Nasa awarded up to US$6.8 billion to aerospace giant Boeing and California-based SpaceX to launch astronauts into space.

In a throwback to the golden age of space flight, the contracts call for Apollo-like capsules that would ferry astronauts to the International Space Station. The space agency chose not to return to the winged space shuttle design, electing instead to build vehicles that would be lifted into space atop a rocket, travel to the space station and then splash down in the ocean.

The contracts - one to an aerospace stalwart and another to an upstart - also reflect new realities of funding space missions: they must be affordable.

Nasa, which has preferred in the past to own and operate spacecraft, will now rely on commercial vehicles that it will essentially rent.

"Turning over low-earth orbit transportation to private industry will also allow Nasa to focus on an even more ambitious mission - sending humans to Mars," Nasa administrator Charles Bolden said on Tuesday at a news conference at Kennedy Space Centre in Florida.

The contracts return southern California, once the epicentre for space shuttle development, to a prime role in space flight.

It was a major announcement for Nasa, but even bigger for SpaceX and its founder, Elon Musk.