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

Iran PressAmerica: The US military’s secretive X-37B robot spaceplane has blasted off from Florida on its seventh mission, the first launched atop a SpaceX Falcon Heavy rocket capable of delivering it to a higher orbit than ever before.

The space plane took off aboard SpaceX's Falcon Heavy rocket from NASA's Kennedy Space Center at night, more than two weeks late because of technical issues.

It marked the seventh flight of an X-37B, which has logged more than 10 years in orbit since its debut in 2010.

The last flight, the longest one yet, lasted two and a half years before ending on a runway at Kennedy a year ago.

Built by Boeing, the X-37B resembles NASA’s retired space shuttles. But they’re just one-fourth the size at 29 feet (9 meters) long. No astronauts are needed; the X-37B has an autonomous landing system. 219