An Orion space capsule developed to fly astronauts to asteroids, the Moon and eventually to Mars has arrived at the Kennedy Space Centre ahead of its planned test flight.
The spacecraft, built by Lockheed-Martin, is expected to be launched by an unmanned Delta 4 Heavy rocket from Cape Canaveral Air Force Station, next to the Nasa spaceport in Florida, in 2014.
Although it is designed to carry a crew of four, Orion will make its first two flights unmanned.
"It's not a PowerPoint chart. It's a real spacecraft," said Kennedy Space Centre director Bob Cabana during a ceremony marking the arrival of the capsule.
The 2014 launch is intended to test Orion's heat shield, parachutes and other systems.
It is expected to reach about 3,450 miles above Earth - more than 10 times beyond where the International Space Station (ISS) flies.
It will then re-enter Earth's atmosphere with 84% of the force that a spaceship returning from the Moon would have.
"It's really going to stress the heat shield, which is exactly what we're trying to do," said Nasa programme manager Mark Geyer.
A second test flight in 2017 using Nasa's planned heavy-lift Space Launch System rocket is intended to put an unmanned Orion capsule around the Moon.
The third test flight, which has been pencilled in for 2021, is expected to have a flight crew.
By 2025, Nasa intends to send astronauts to explore a near-Earth asteroid before heading on to Mars in the 2030s.
Humans have not flown beyond a few hundred miles above Earth since 1972 when the Apollo missions to the Moon ended.
With the retirement of the Nasa space shuttles last summer, the US is dependent on Russia to fly crews to the space station, a £64bn project involving 15 countries that orbits about 240 miles above the planet.
In the hope of breaking Russia's monopoly, Nasa is teaming up with four companies that are interested in developing spaceships to fly astronauts, as well as private researchers and tourists to the ISS and other planned outposts in orbits close to Earth.
The Delta 4 rocket which will be used for Orion's second test flight is made by United Launch Alliance, a partnership of Lockheed-Martin and Boeing.
