Air Force Security Forces personnel set up a security perimeter around the space shuttle. Air Force Security Forces personnel set up a security perimeter around the space shuttle Discovery and NASA's 747 Shuttle Carrier aircraft at Barksdale Air Force Base, La., on Aug. 19, 2005. The 747 and its piggy-backed Discovery stopped for a planned overnight refueling on its way back to Kennedy Space Center, Fla. SHARE IMAGE: Download Image: Full Size (0.05 MB) Photo By: VIRIN: 617708-G-RZW67-661.jpg Photo Gallery