SpaceX will return stranded astronauts next year

SpaceX has so far sent nine crewed flights to space for Nasa, as well as some commercial missions, but this was Boeing’s first attempt at a crewed mission.

Engineers at Boeing and Nasa have spent months trying to understand the technical issues with the Starliner craft.

They have been carrying out tests and gathering data, both in space and back on the Earth. Their hope was to pin down the root of the problems and find a way to return the astronauts home safely on Starliner.

Speaking at a press conference on Saturday, Nasa Administrator Bill Nelson said Boeing has been working closely with Nasa to understand what improvements need to be made to the spacecraft.

"Space flight is a risk, even at its safest and even at its most routine, and a test flight, by nature, is neither safe nor routine," he said.

"Our core value is safety and it is our north star."

The decision has been made to extend the pair's stay on the ISS until February 2025 so they can return on a SpaceX Crew Dragon spacecraft.

The extra time allows SpaceX to launch its next vehicle, with lift-off scheduled for the end of September.

It was supposed to have four astronauts on board, but will instead travel to the space station with two. This leaves room for Mr Wilmore and Ms Williams to join them in the vehicle to return to Earth at the end of its planned mission next February.

Nasa has said both astronauts had previously completed two long-duration stays in space and understood the risks of the test flight, including being aboard the station longer than planned.