CAPE CANAVERAL, Fla. — An ailing astronaut returned to Earth with three others on Thursday, ending their space station mission more than a month early in NASA’s first medical evacuation. SpaceX guided the capsule to a middle-of-the-night splashdown in the Pacific near San Diego, less than 11 hours after the astronauts exited the International Space Station . Their first stop was a hospital for an overnight stay. “Obviously, we took this action (early return) because it was a serious medical