Outer space

X-37B Military Space Plane Breaks Record on Latest Mystery Mission

The U.S. Air Force's X-37B space plane just broke its spaceflight-duration record.

At 6:43 a.m. EDT (1043 GMT) today (Aug. 26), the robotic X-37B sailed past the program mark of 717 days, 20 hours and 42 minutes, which was set by the previous mission, known as Orbital Test Vehicle 4 (OTV-4).

The current mission, OTV-5, began on Sept. 7, 2017, with a liftoff atop a SpaceX Falcon 9 rocket. It's unclear what the space plane is doing up there now, or what it has done on past flights; X-37B missions are classified, and the Air Force therefore tends to speak of the vehicle and its activities in general terms.

"The primary objectives of the X-37B are twofold; reusable spacecraft technologies for America’s future in space and operating experiments which can be returned to, and examined, on Earth," Air Force officials wrote in the X-37B fact sheet.

"Technologies being tested in the program include advanced guidance, navigation and control, thermal protection systems, avionics, high temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, advanced propulsion systems, advanced materials and autonomous orbital flight, reentry and landing," the officials added.