An American spacecraft landed itself at a military base in California on the weekend, ending a 15-month mission—but don't expect to hear much about what the unmanned plane was doing up there. The X-37B Orbital Test Vehicle is an Air Force plane and while the military says the mission's main aim was to test the robotically controlled reusable spacecraft technology involved, there was a classified payload on board and there has been much speculation about the mission's purpose, the AP reports. An identical spacecraft completed a 7-month mission in 2010.
Officials say the X-37B, which was launched from Cape Canaveral atop an Atlas V rocket last March, conducted in-orbit experiments during the mission. "With the retirement of the space shuttle fleet, the X-37B OTV program brings a singular capability to space technology development," the X-37B's program manager says. "The return capability allows the Air Force to test new technologies without the same risk commitment faced by other programs." The X-37B's sister spacecraft is expected to head into orbit for a new mission this fall.