X-37B Orbital Test Vehicle, unmanned spacecraft set to launch

The X-37B Orbital Test Vehicle in the encapsulation cell at the Astrotech facility in April 2010, in Titusville, Fla. Air Force officials are scheduled to launch the X-37B April 21, 2010, at Cape Canaveral Air Station, Fla. The X-37B is the U.S.'s newest and most advanced unmanned re-entry spacecraft. (Courtesy photo) (Photo by DoD/Corbis via Getty Images)