After nearly two years in orbit on a top-secret mission, the Air Force's X-37B unmanned space plane landed at Vandenberg Air Force Base, in California, on Friday.
Made by Boeing, the X-37B resembles a miniaturized space shuttle. It has completed two previous missions, but the third was months longer. While Boeing has claimed that the Orbital Test Vehicle was exploring "reusable vehicle technologies in support of long-term space objectives," the Air Force has remained murkier on its purpose, saying only that it had been conducting "on-orbit experiments," The Associated Press reports.
The X-37B is slated to launch again in 2015, from its new home base in Cape Canaveral, Florida.