Engineers say multiple lightning strikes near the launch pad Saturday caused no apparent problems.
Engineers spent the day Sunday readying the rocket, the most powerful ever built by NASA, for the start of fueling just after midnight when 750,000 gallons of supercold liquid oxygen and hydrogen rocket fuel will be pumped aboard the 322-foot-tall SLS.
While the primary goal of the 42-day mission is to test the Orion capsule's heat shield at the end of the flight, the SLS booster has to send the spacecraft on its way, boosting it into Earth orbit and then sending it off on a five-day trajectory to the moon. "We are excited. The vehicle is going to be ready. It's ready right now, it looks great to proceed with this inaugural launch of the Artemis program."