An unmanned US plane on a top-secret, two-year mission to space has returned to Earth and landed in California.
The aircraft, resembling a miniature space shuttle and known as the Orbital Test Vehicle or X-37B, spent 674 days in orbit around the planet.
It was the unmanned plane’s third space flight, but its mission has been shrouded in mystery.
A theory that it was taking a look at China’s space lab has been downplayed by experts.
Air Force officials have only told US media the aircraft performs “risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies”.