The secretive U.S. Air Force X-37B robotic space plane has been cleared to lift off Tuesday.

The X-37B vehicle and its cargo bay packed with a classified payload is set to make the third mission of the program. Also called Orbital Test Vehicle-3, or OTV-3, the unpiloted craft is slated to be hurled into Earth orbit by an Atlas 5 rocket from Florida's Cape Canaveral Air Force Station (CCAFS) at 1:03 p.m. EST.

There's an interesting angle to the upcoming mission. This third flight will use the same X-37B spacecraft that flew the first test flight, the OTV-1 mission, in 2010.


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