Excerpt from

nbcnews.com

The U.S. Air Force will take over two mothballed space shuttle processing hangars at the Kennedy Space Center in Florida for its secretive X-37B robotic space plane program, said Wednesday. The agreement transfers two of the shuttle’s three processing hangars for the military’s X-37B Orbital Test Vehicles, built and managed by Boeing. 
The 29-foot-long (9-meter-long) space planes resemble miniature space shuttles. The Air Force currently has two vehicles, one of which has been in orbit since December 2012. The military has not disclosed what the X-37B is doing in orbit, nor when or where it will land. Two prior X-37B missions lasted 224 days and 469 days respectively, and landed autonomously at Vandenberg Air Force Base in California. Boeing is to use the third shuttle hangar for its NASA-backed CST-100 commercial space taxis. 
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