The U.S. military\u2019s X-37B space plane blasted off Thursday on another secretive mission that\u2019s expected to last at least a couple of years.<\/p>\n\n\n\n
Like previous missions, the reusable plane resembling a mini space shuttle carried classified experiments. There\u2019s no one on board.<\/p>\n\n\n\n
The space plane took off aboard SpaceX\u2019s Falcon Heavy\u2002<\/a>rocket from NASA\u2019s Kennedy Space Center at night, more than two weeks late\u2002<\/a>because of technical issues.<\/p>\n\n\n\n It marked the seventh flight of an X-37B, which has logged more than 10 years in orbit since its debut in 2010.<\/p>\n\n\n\n The last flight, the longest one yet, lasted 2 \u00bd years before ending on a runway at Kennedy a year ago.<\/p>\n\n\n\n Space Force officials would not say how long this orbital test vehicle would remain aloft or what\u2019s on board other than a NASA experiment to gauge the effects of radiation on materials.<\/p>\n\n\n\n Built by Boeing, the X-37B resembles NASA\u2019s retired space shuttles. But they\u2019re just one-fourth the size at 29 feet long. No astronauts are needed; the X-37B has an autonomous landing system.<\/p>\n\n\n\n They take off vertically like rockets but land horizontally like planes, and are designed to orbit between 150 miles and 500 miles high. There are two X-37Bs based in a former shuttle hangar at Kennedy.<\/p>\n\n\n\n