The US Air Force's highly secret robotic space plane continues to circle our planet a year after being launched, with no authoritative version of the shadowy mission purpose presented to public. Since the original test mission of the first X-37B Orbital Test Vehicle One (OTV-1) that was performed in April 2010 and lasted the promised 270 days, the US Air Force has been insisting the X-37 program is a purely scientific undertaking and a testing platform of new technology. Very little has been revealed about the spacecraft. The only information available on the successive OTV-2 mission launched on March 5, 2011, with an Atlas 5 booster rocket from the Cape Canaveral Air Force Station in Florida is that the space plane is an 8.8-meter- long and 4.5-meter-wide solar-powered vehicle. The experimental spacecraft was supposed to return to an airstrip in California nine months later in December – but that never happened.