Another U.S. military mini shuttle has blasted off on a secret mission. Launched Thursday by SpaceX, the craft with no one aboard took off from Florida. It’s the eighth such flight for the space planes known as X-37B. This U.S. Space Force says this flight will test laser and navigation technologies. It’s not yet clear how long the mini shuttle will remain aloft. Previous missions have lasted months to years. The Boeing-made reusable space planes were first launched in 2010.