(Merritt Island, FL) -  The rocket launch to the moon this morning has been postponed.

NASA officials said the launch was canceled because of a fuel leak and engine problems. The fueling ran nearly an hour late Monday because of thunderstorms off Florida's Kennedy Space Center. 

The over 300-foot spaceship is the most powerful rocket ever built by NASA. The next launch attempt could happen as soon as Friday.  

No astronauts were inside. Instead, three test dummies were strapped for the six-week mission, scheduled to end with the capsule's splashdown in the Pacific in October.