SpaceX's Falcon 9 rocket launched on Thursday, carrying the U.S. Air Force’s X-37B into orbit.

Although few details of the mission were revealed, we know it's the fifth flight for the Boeing-built spaceplane, and the first time it’s been launched by SpaceX. The Air Force said the plane is carrying “experimental payloads," including satellites and new electronics.

The X-37B returned to Earth in May after a two-year space mission. And you guessed it: the Air Force was vague about that mission, too.