CAPE CANAVERAL, Fla.—Elon Musk’s private rocket company, SpaceX, was due to launch four more astronauts to the International Space Station for NASA on Wednesday, including a veteran spacewalker and two younger crewmates chosen to join NASA’s forthcoming lunar missions. The SpaceX-built launch vehicle, consisting of a Crew Dragon capsule perched atop a two-stage Falcon 9 rocket, was set for liftoff at 9:03 p.m. from NASA’s Kennedy Space Center in Cape Canaveral, Florida. If all goes smoothly, the three U.S. astronauts and their European Space Agency (ESA) crewmate will arrive about 22 hours later and dock with the space station 250 miles (400 kilometers) above the Earth to begin a six-month science mission aboard the orbiting laboratory. Liftoff originally was slated for Oct. 31 but has been repeatedly rescheduled due to a spate of bad weather. One delay was attributed to an unspecified medical issue with a crew member, the first …