U.S. military's mystery space plane rockets back toward orbit

The U.S. military's mystery space plane rocketed into orbit again Sunday, this time with an extra load of science experiments. It's the sixth flight of an X-37B, a solar-powered plane that's flown by remote control without a crew. Officials aren't saying how long the spacecraft will remain in orbit this time or the purpose of the mission. But a senior vice-president for X-37B developer Boeing, Jim Chilton, noted each mission has been progressively longer. The previous mission lasted a record two