美国发射试验飞船

(文本为视频大致内容，可能与视频并非完全一致)

The US Air Force has launched an experimental space plane from Cape Canaveral in Florida. It was scheduled to take off on Friday, but was postponed due to bad weather.

This is the second mission of the unmanned, winged space craft. The first finished in April after a 270-day mission. The purpose of the X-37B - and details about the plane - remain a mystery.

Some analysts believe the recorded orbits suggest the craft may be used to assess the possibility of weapons delivery from space. While others believe it's more likely the flight is used for military surveillance.