Specially garbed technicians attend to an X-37B spacecraft after it landed at NASA's Kennedy Space Center in Florida, ending the fourth Orbital Test Vehicle (OTV-4) mission in May of last year. | US Air Force

Clandestine X-37B Space Plane Surpases 200 Days in Orbit

The US Air Force’s unpiloted and reusable craft is likely to be testing dual-use technologies that might be used in military operations, says one expert.