Update for 7 a.m. ET: SpaceX successfully launched four astronauts to the International Space Station on the Crew-12 mission.

The International Space Station returned to full strength with Saturday’s arrival of four new astronauts to replace colleagues who bailed early because of health concerns.

The US space agency's international Crew-12 blasted off at approximately 5:15 am local time (1015 GMT) aboard a SpaceX Falcon 9 rocket from the Cape Canaveral launch site in Florida, according to a NA...