Launch preparations have begun for the Artemis II mission, NASA’s planned lunar fly-around by four astronauts that will be the first moon trip in 53 years. Tensions were high as hydrogen fuel started flowing into the rocket. The 32-story Space Launch System rocket is poised to blast off Wednesday evening with a two-hour launch window beginning at 6:24 p.m. EDT at Kennedy Space Center in Florida. Three Americans and one Canadian will fly around the moon without stopping or even orbiting — then head straight back for a Pacific splashdown. They will set a new distance record for the farthest humans have traveled from Earth. Artemis II is the opening shot of NASA’s grand plans for a permanent moon base.