The United States has launched a high-tech, experimental spaceplane for the third such flight in a secretive military test program.

The nearly eight-meter-long X-37B craft blasted off Tuesday from Cape Canaveral, Florida, on an Atlas V rocket.

The unmanned shuttle made the first flight of its kind in 2010 and spent seven months circling Earth. A separate X-37B spacecraft was launched in 2011 and spent more than a year in space.