US space agency NASA has said it is still deciding whether to keep two astronauts at the International Space Station (ISS) until early next year and to send their troubled Boeing capsule back to Earth empty.
Rather than returning on the Starliner, Butch Wilmore and Suni Williams would catch a ride on SpaceX’s next flight - an option would keep them at the ISS until next February.
The test pilots anticipated being away for just a week or so when they blasted off as Starliner’s first crew.
However, thruster failures and helium leaks marred the capsule’s trip to the ISS, raising doubts about its ability to return safely and leaving the astronauts in limbo.
NASA officials said they are analysing more data before making a decision about what to do by the end of next week or the beginning of the next.
The thrusters are crucial for holding the capsule in the right position when it comes time to descend from orbit.
"We’ve got time available before we bring Starliner home and we want to use that time wisely," NASA’s Associate Administrator for Space Operations Ken Bowersox said.
Switching to SpaceX would require bumping two of the four astronauts assigned to the next ferry flight, currently targeted for late next month.
Mr Wilmore and Ms Williams would take the empty seats in SpaceX’s Dragon capsule once that half-year mission ends.
Watch: Boeing's Starliner astronauts arrive at ISS
Another complication is that the space station has just two parking places for US capsules.
Boeing’s Starliner would have to depart ahead of the arrival of SpaceX’s Dragon in order to free up a spot.
NASA would like to keep SpaceX’s current crew on the ISS until the replacements arrive, barring an emergency.
Those four should have returned to Earth this month, but saw a seventh month added to their mission because of the uncertainty over Starliner, keeping them up there until the end of September.
Most space station stays last six months, although some have gone a full year.
Eager to have competing services and backup options, NASA hired SpaceX and Boeing to transport astronauts to and from the ISS after retiring its shuttles in 2011.
SpaceX’s first astronaut flight was in 2020. Boeing suffered so much trouble on its initial test flight without a crew in 2019 that a new attempt was ordered.
More problems then cropped up, costing the company over €1 billion (€908m) to fix before finally flying astronauts.
