The X-37B, the U.S. Air Force’s secret robotic space plane, has now been in orbit for almost 500 days, a record-breaking time period for space endurance. The latest version of the relatively tiny spacecraft, which is just one quarter of the size of the space shuttles, was launched in December 2012 on a top-secret mission. … Continue reading USAF Plane is Orbiting Earth for 500 Days on a Top Secret Mission