The U.S. Air Force’s X-37B space plane, built by Boeing, winged past 200 days in orbit on its latest clandestine mission. The robotic craft launched atop a SpaceX Falcon 9 booster on Sept. 7, 2017. It was carrying cargo used to test experimental electronics and oscillating heat pipes for long durations in space.

Intrigued? Learn more about the plane and mission.