Air Force X-37B space plane launched into orbit

An experimental robotic space plane was launched into orbit atop a massive Atlas V rocket Saturday for a classified Air Force mission that could last up to nine months.

The 19-story Atlas V and the space plane, dubbed the X-37B Orbital Test Vehicle, blasted off from Cape Canaveral in Florida at 5:46 p.m. Eastern time.

The unmanned X-37B, which resembles a miniature space shuttle, is about 29 feet long with a wingspan of about 15 feet. The spacecraft draws solar power for energy using unfolding panels.