Sen— Engineers are about to construct Orion's heat shield ahead of the spacecraft's first workout in 2014, NASA said in an update on the program.
The spacecraft - which NASA is touting as a new generation of human spaceflight vehicle - is designed to take people out of Earth orbit to other destinations, which could include the Moon, asteroids and Mars.
The 2014 flight test will encompass two orbits of Earth. The spacecraft will soar as high as 5,800 kilometres (3,600 miles) above the surface - 15 times higher than the International Space Station - before making the plunge into the atmosphere.
Orion's 2014 flight will be the first high-altitude, high-speed re-entry for a human-rated space vehicle since the Apollo era. Much of the mission's success will ride on a heat shield undergoing assembly at contractor Lockheed Martin.
Workers will carefully bolt a carbon fibre skin on to Orion's titanium skeleton. The painstaking process requires nearly 3,000 bolts, and will be finished by January.
Orion's heat shield will then travel more than halfway across the United States - from Colorado to Boston - to another contractor, Textron Defense Systems. There, a protective coating (Avcoat) will be applied to the shield to make it heat-resistant.
"The biggest challenge with Avcoat has been reviving the technology to manufacture the material such that its performance is similar to what was demonstrated during the Apollo missions," said John Kowal, Orion's thermal protection system manager at NASA, in a 2009 statement.
The spacecraft also achieved several engineering and mission milestones in recent weeks.
NASA has just received the materials necessary to connect Orion with its Delta IV rocket during the launch. That rocket is only being used for initial testing, as NASA is currently designing a heavy-lift rocket to send Orion further into space. The connector is supposed to work on both rockets.
Further, NASA's ground support team for the Orion launch has received approval for its budget and schedule, as well as the proposal to put infrastructure in at the Kennedy Space Center. This will allow NASA to move into preliminary design for the launch complex.
The agency is also working with the U.S. Navy to outline the recovery procedures for when Orion first splashes down in its test.
Orion originally began as a part of NASA's Constellation program, which was intended to return US astronauts to the Moon and eventually Mars. The program, conceived under President George W. Bush, was abandoned after Barack Obama took office. But the spacecraft was repurposed as a multi-purpose crew vehicle.
Whilst NASA is developing Orion as its own brand spaceship for deep space, it is also providing development funding to SpaceX and other companies building spacecraft for shorter journeys, in particular to ferry astronauts to and from the International Space Station.