The mission of the X-37B is classified. This drone was designed by the US Air Force and launched into space by the NASA. It has been more than two years in space to do several tests.
Only the test of a new propellant and the other one which consist into observing the evolution of certain materials in space have been revealed to the public.
Satellite enthusiasts were able to observe the movements of the drone in space and noted that a satellite had never moved that much before.
This drone looks like a shuttle and is put into orbit in a conventional way, on an Atlas 5 rocket.