For weeks, Nasa has downplayed problems experienced by Starliner, a Boeing spacecraft that took two astronauts to the International Space Station in June.

But on Wednesday, Nasa officials admitted that the issues might be more serious than first thought and that the astronauts might not return on the Boeing vehicle, after all.

The agency is exploring a backup option for the astronauts, Sunita Wiliams and Butch Wilmore, to instead hitch a ride back to Earth on a spacecraft built by Boeing’s competitor SpaceX.

The astronauts’ stay in orbit, which was to be as short as eight days, could be extended into next year.

“We could take either path,” Ken Bowersox, Nasa’s associate administrator for the space operations mission directorate, said during a news conference on Wednesday. “And reasonable people could pick either path.”

The announcement adds more headaches and embarrassment for Boeing, an aerospace giant that has billions of dollars of aerospace contracts with the federal government and builds commercial jets that fly all around the world.

Under the contingency plan, the next SpaceX Crew Dragon capsule would travel to the space station with only two astronauts instead of four. Williams and Wilmore would then join as full-fledged members of the space station crew for a half-year stay and return on the Crew Dragon around next February.

New York Times News Service