On Friday evening, the Air Force's second top secret Orbital Test Vehicle is scheduled to launch from Cape Canaveral Air Force Station in Florida.
The hush-hush mission of a robotic miniature space shuttle, known in military parlance as the "Orbital Test Vehicle," or X-37B, is heading for a California landing this week, the Air Force said Tuesday.
The Air Force's secrecy-shrouded unmanned space plane returned to Earth early Friday.