NASA astronauts Butch Wilmore and Suni Williams arrived at the ISS aboard Boeing's Starliner spacecraft last June. The duo were flying the capsule's first crewed flight test, which was expected to stay in orbit for about 10 days before flying the pair back to Earth.

During a second attempt, SpaceX successfully launched a mission on March 14 to replace two NASA astronauts who have been stuck on the International Space Station for nine months.