Mystery surrounds the U.S. military's Orbital Test Vehicle, the X-37B OTV, which launched into space ... from the Cape Canaveral Air Station in Florida. Is it an aircraft? Is it the next generation space shuttle? How much does it cost? And why is it such a secret? The X-37B OTV is a classified Air Force project that has never been fully explained by the Pentagon. Some worry it may be the start of military operations in space -- that the plane might some day carry weapons to shoot down enemy satellites. Some are concerned it may be used as a quick-response vehicle that could be sent very quickly with weapons to a danger spot, said Victoria Samson of the Secure World Foundation. Unlike the re-usable space shuttle, the X-37B is unmanned and much smaller. It is controlled from ground stations. It can stay in space for 270 days, but the Air Force won't say how long it's staying up this time or what exactly it will be doing other than testing out its high tech guidance and navigation. The Air Force won't even say how many billions of dollars it's spending on the program. The OTV is the first vehicle since NASA's shuttle orbiter that has the ability to return experiments to Earth for further inspection and analysis, the Air force said.

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