NASA cleared its moon rocket on Thursday for an April launch with four astronauts after completing the latest round of repairs. The 322-foot (98-meter) rocket will roll out of the hangar and back to the pad next week at Florida’s Kennedy Space Center,

Although NASA managed to plug the hydrogen fuel leaks at the pad in February, a helium-flow issue forced the space agency to return the rocket to the Vehicle Assembly Building for repairs, bumping the...