Posted: Fri, Apr 23, 2010, 7:01 AM ET (1101 GMT)

An Atlas 5 rocket launched a secretive military spaceplane Thursday evening. The Atlas 5 501 lifted off from Cape Canaveral, Florida, at 7:52 pm EDT (2352 GMT) and placed the X-37B vehicle into low Earth orbit about 20 minutes later. The X-37B, also called the Orbital Test Vehicle, is an unmanned "mini-shuttle" designed to test various unspecified technologies and then reenter, gliding to a runway landing in California. The X-37 was initially a NASA program to demonstrate RLV technologies, but later transferred to DARPA and then the Air Force, which has released few details about the vehicle and its mission.