The U.S. Air Force’s X-37B miniature space plane has winged past 340 days in orbit performing secretive duties during the program’s fifth flight.

The robotic craft’s latest mission, known as Orbital Test Vehicle-5 (OTV-5), kicked off on Sept. 7, 2017, with a launch atop a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center (KSC) in Florida.

As usual, Air Force officials have revealed few details about OTV-5. But we do know that one payload flying aboard the X-37B this time around is the Advanced Structurally Embedded Thermal Spreader, or ASETS-11. Developed by the U.S. Air Force Research Laboratory, this cargo is testing experimental electronics and oscillating heat pipes for long durations in the space environment.