U.S. astronauts Butch Wilmore and Suni Williams could be back on Earth as soon as Tuesday. The pair has been in space for nearly 300 days due to issues with the spacecraft they arrived in: Boeing's Starliner.

NASA removed two astronauts from its Crew-9 mission to allow for Williams and Wilmore to join the cohort, and return onboard the SpaceX Dragon − which carries four people at a time. The altered Crew-9 − only Hague and Gorbunov − launched aboard the SpaceX Dragon Freedom in late September.

The Boeing Starliner they took to the space station almost didn't make it. Soon after liftoff in June, helium leaked and thrusters malfunctioned. NASA and Boeing spent the summer trying to figure out what went wrong and whether the problems would repeat on the flight back.