Article from the website phys.org.
A robotic space plane is speeding in low Earth orbit at this very moment. Some say it's a weapon; others, a data-gathering mission. There's one fact most agree on as the plane hits 500 days in space: Its real purpose is a mystery.
The Boeing-built X-37B Orbital Space Vehicle, constructed in California, is one-fourth the size of the Endeavour Space Shuttle.
The Air Force craft, purely a test vehicle that will never reach production, in part aims to explore reusable space-vehicle technologies. That means the robotic vehicle can land, but no one will say when.
What could it be?
Click on this link to read more http://phys.org/news/2014-04-mysterious-robotic-plane-days-space.html.