An experimental robotic space plane developed for the Air Force is slated to launch Friday from Cape Canaveral, fueling an ongoing mystery about its hush-hush payload and overall mission.
Watching the pilotless spacecraft along with the Pentagon will also be wary Russian and Chinese military officials who have raised questions about U.S. intentions since the government launched its first version of the secret plane into orbit almost a year ago.
The X-37B Orbital Test Vehicle looks like a miniature version of the space shuttle. Because of its clandestine nature, some industry analysts have theorized it could be a precursor to an orbiting weapon, capable of dropping bombs or disabling foreign satellites as it circles the globe.
"It's a mystery, because the Air Force is being so closed-mouthed about the program," said Brian Weeden, a former Air Force officer and expert in space security. "It leads people to say, 'What exactly are they hiding?' "