Mystery Mission: Air Force's X-37B Space Plane Nears 1 Year in Orbit
Tuesday, May 10, 2016 - 08:01
in Astronomy & Space
The robotic space plane launched atop a United Launch Alliance Atlas V rocket on May 20, 2015, kicking off the X-37B program's fourth flight. This mission, dubbed OTV-4 (short for Orbital Test Vehicle-4), remains a clandestine affair.