The military's mysterious, experimental unmanned space plane is doing such a good job that its mission has been extended indefinitely—if only anyone knew what its mission was.
Details on the mission involving the X-37B are virtually nonexistent. The official U.S. Air Force fact sheet says the vehicle is being used as an "experimental test program to demonstrate technologies for a reliable, reusable, unmanned space test platform for the U.S. Air Force."
In November, the Air Force announced that the X-37B's mission was being extended beyond its planned 270 days. At a breakfast with reporters Thursday, General William Shelton, head of the Air Force Space Command, said the mission, whatever it is, has been extended indefinitely.
"We don't have an exact re-entry date for it, but we've had a successful mission and we're very happy with its performance," he said. "That vehicle is performing a great service."
Asked to give adjectives for the X-37B, he offered up "spectacular," and "game-changing."
In January, Spaceflight magazine reported that the vehicle is closely following the orbit of China's spacelab, Tiangong-1, leading the magazine to suspect that the X-37B is spying on that satellite.
"Space-to-space surveillance is a whole new ball game made possible by a finessed group of sensors and sensor suites, which we think the X-37B may be using to maintain a close watch on China's nascent space station," Spaceflight editor David Baker told the BBC in January. China is expected to send manned missions to Tiangong-1 later this year.
Other experts have refuted Baker's claims, speculating that the X-37B could be used to covertly deploy smaller satellites, while conspiracy theorists have wondered if the X-37B could deliver weapons from space.
Here's what is known about the X-37B: The 29-foot ship was built in a Huntington Beach, Calif., lab by Boeing. It looks like a miniature, solar-powered version of a space shuttle, and it's the second "orbital test vehicle" the military has launched into space—the first was launched in 2010. The Air Force calls it the "newest and most advanced re-entry spacecraft," and it has the ability to land autonomously. Technologies being tested "include advanced guidance, navigation and control, thermal protection systems, avionics, high temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, and autonomous orbital flight, reentry and landing."
Beyond that, the X-37B has been shrouded in secrecy—from its mission to its budget. Thursday, Shelton repeatedly dodged questions about what the military is up to with the ship.
"I think there's a good reason to keep [the budget of the X-37B] as quiet as we possibly can," he said. "If you reveal budgets, you sometimes reveal the capabilities, the amount of technology inserted into a program. It's a good, strategic national security decision."