Elon Musk's rocket company SpaceX was due to launch the next long-duration crew of the International Space Station into orbit on Wednesday, with a Russian cosmonaut hitching a ride with two Americans and a Japanese astronaut as part of the mission.
The SpaceX launch vehicle, consisting of a Falcon 9 rocket topped with a Crew Dragon capsule dubbed Endurance, was set for liftoff at noon EDT (1600 GMT) from NASA's Kennedy Space Center in Cape Canaveral, Florida.
The four-member crew should reach the International Space Station (ISS) about 29 hours later on Thursday evening to begin a 150-day science mission aboard the orbital laboratory some 250 miles (420 km) above Earth.