US military space plane blasts off on secretive years-long mission

The X-37B is on a mission expected to last at least a couple of years (US Air Force via AP)

The US military’s X-37B space plane has blasted off on another secretive mission, expected to last at least a couple of years.

Like previous missions, the reusable plane resembling a mini-space shuttle carried classified experiments. There is no-one on board.