The U.S. space shuttle Discovery lifted off on Sunday from Cape Canaveral, Florida on a mission of delivering the International Space Station's fourth and final set of solar array wings, to complete the station's truss, or backbone, Xinhua reported.
Discovery entered a launch countdown last Wednesday, before ground crews at NASA's Kennedy Space Center in Cape Canaveral noticed a hydrogen leak in a liquid hydrogen vent line between the shuttle and the external tank. The leak forced NASA to immediately begin unloading fuel from the tank and cancel the Wednesday launch.
The shuttle was initially scheduled for launch on Feb. 12, but concerns over suspect fuel control valves in the spacecraft's main engines prompted several delays so engineers could replace them.