The Pentagon's Mystery Spaceplane Takes Off
On April 22, 2010, an Atlas V lifted off from Cape Canaveral carrying a reusable robotic spaceplane so secret that the Air Force would not even confirm its mission duration. It came back 224 days later, lighter, quieter, and more operational than anyone outside Washington had expected. Fifteen years later, the X-37B is still flying, and the military still will not say what it does.