The United States Air Force's X37-B OTV-2 space plane was expected to land today, following a 270 day non-stop orbit of Earth, however those plans have been scrapped as the stamina of the plane has exceeded the expectations of its designers. Powered by solar cells which unfold from the vehicle's cargo bay, the plane is unmanned and is used as a research facility to test how well satellite sensors and other instruments perform in low gravity. The craft resembles a miniature space shuttle, and orbits at roughly 255 miles above the Earth's surface. 

It's built by Boeing in its Phantom Works division in tight secrecy, which has led some commentators to suggest that the craft might be a precursor for similar designs used in military operations. Other possible future uses for the plane include carrying supplies and personnel to the international space station, which would allow NASA to fill the gap left by the shuttle program without resorting to the likes of Virgin Galactic or Jeff Bezos' Blue Origin.