Bad weather has postponed the launch of NASA's Messenger spacecraft to the planet Mercury. Managers stopped the launch because of clouds near the pad at a critical point in the countdown. There was only a 12-second launch window. NASA hopes to try again early Tuesday. Messenger is set to begin a seven year, four-point-nine (b) billion mile journey to orbit the planet nearest the sun and collect data on its geology and atmosphere. It will be the first spacecraft to visit the planet since Mariner Ten whizzed by in 1974 and 1975. It will also be the first spacecraft ever to orbit Mercury.