KENNEDY SPACE CENTER, Florida—For the first time in nearly 54 years, humans are on their way to the moon. At 6:35 P.M. EDT, NASA’s Artemis II mission blasted off from Kennedy Space Center. It’s the second flight in the agency’s moon-focused Artemis program and the first with humans onboard. The hulking Space Launch System (SLS)—a 322-foot-tall rocket flanked by boosters emblazoned with a patriotic logo celebrating the 250th birthday of the U.S.—shook the earth as it leaped from the pad.