Chinese spacecraft returns to Earth after mysterious 276-day mission.

An experimental Chinese spacecraft, the details of which have not been disclosed, returned to Earth after 276 days in orbit, marking an "important" breakthrough in China's research into reusable spacecraft technology. The spacecraft's mission was to test China's reusable space technologies, which will provide a more convenient and inexpensive way to mount future space missions. The spacecraft's design has led to speculation that it is similar to the US Air Force's X-37B, an autonomous spaceplane that can remain in orbit for years.