After repairing fuel leaks and figuring out how to get around a faulty engine sensor that prevented the first attempt, NASA is aiming for a Saturday launch of its new moon rocket.

The inaugural flight of the 322-foot (98-meter) rocket — the most powerful ever built by NASA — was delayed late in the countdown Monday. The Kennedy Space Center clocks started ticking again as managers expressed confidence in their plan and forecasters gave favorable weather odds.

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Atop the rocket is a crew capsule with three test dummies that will fly around the moon and back over the course of six weeks — NASA’s first such attempt since the Apollo program 50 years ago. NASA wants to wring out the spacecraft before strapping in astronauts on the next planned flight in two years.

NASA Administrator Bill Nelson said he’s more confident going into this second launch attempt, given everything engineers learned from the first try.