The Air Force’s mysterious X-37B spaceplane successfully launches to space on sixth mission

Update May 17th, 9:30AM ET: The X-37B successfully took off at 9:14AM ET on Sunday, though ULA ended live coverage of the mission early at the request of the Air Force.

Original Story: The Air Force’s mysterious spy spaceplane, dubbed the X-37B, is headed back to space on Sunday morning for its sixth mission in Earth orbit. As usual with this spacecraft, its exact purpose is a secret, though the Air Force says the vehicle will be carrying a number of experiments on this trip and testing out new systems in space before returning them to Earth.

This launch comes a little more than six months after the X-37B returned home from its record-breaking fifth mission to orbit. The spaceplane, which looks a bit like a miniature Space Shuttle,…