It is to serve as the test flight vehicle for a new series of commercial passenger spaceliners that will be operated by Virgin Atlantic Airways.

BBC: NEWS | Science/Nature | 'No experiments' for SpaceShipOne

During a second flight test in January, the Raytheon kill vehicle missed the target by 100 feet because two "end-game" sensors both experienced mechanical failures.

CENTERFORSECURITYPOLICY: Center For Security Policy

Like Amazon, the company is secretive, but last September it revealed that it had lost an unmanned prototype vehicle during a short-hop test flight.

ECONOMIST: Brain scan

The astronaut vehicle itself, known as Orion, is nearing its first test flight.

BBC: UK astronaut Tim Peake makes 'asteroid splashdown'