Being stranded in space sounds like the premise of a sci-fi movie, but for two American astronauts, the concept might hit too close to home.

Luckily, they may be able to hitch a ride back home in 2025.

Butch Wilmore and Suni Williams were sent up in June, on the first crewed test flight of a Boeing Starliner to the International Space Station (ISS).

The mission was supposed to last only about eight days.

But the pair’s return has been repeatedly delayed due to the Starliner’s faulty thrusters and helium leaks.

The veteran astronauts have so far remained on the ISS for more than 60 days, and still have no definite return date – although NASA insists they are not stranded.

Wilmore and Williams have kept busy during their extended stay on the ISS, with the NASA sharing images of the pair installing hardware and conducting research.

Last week, NASA said that if Starliner remained unfit for a manned return trip to Earth, the pair might have to wait until early in 2025 to hitch a lift home on a SpaceX vessel.

“We could take either path,” NASA associate administrator for space operations Ken Bowersox said.

“I would say that our chances of an uncrewed Starliner return have increased a little bit based on where things have gone over the last week or two.”

Boeing has attempted to downplay the chances of SpaceX bringing the astronauts home.

In a statement, the company said it was confident in the Starliner’s ability to return safely with crew based on an “abundance of valuable testing from Boeing and NASA”, which confirmed 27 of 28 thrusters were back to full operational capability and helium levels were stable.

But some NASA officials appear wary of the testing data, and a Boeing representative was notably absent from last week’s NASA press conference.

As time goes on, it looks more likely NASA will turn to SpaceX.

“We started in early July, doing some early planning with SpaceX for some of these contingencies,” NASA commercial crew program manager Steve Stich said last week.

“Then as we got closer and a little bit more data, we started to put a few more things in place.

“In the last few weeks, we have decided to make sure we have that capability there, as our community, I would say, got more and more uncomfortable.”

Under the contingency plan, the next SpaceX Crew Dragon capsule, which had been due for launch on August 18 and will now launch on September 24 due to the Starliner delay, will head to the space station with only two astronauts instead of the previously planned four.

Wilmore and Williams would then work alongside the newly-arrived astronauts on the ISS for about six months and return to Earth on the Crew Dragon in February.

Under that plan, Starliner will have to return to Earth without anyone on board before Crew Dragon arrives, so that an ISS docking port is available.

Stich said the final decision about the astronauts’ return arrangements must be made by mid-August.

Experts told The Guardian the snafu was not unusual given the Boeing Starliner mission was a test flight.

But the failure would still be a major blow for Boeing, which has endured several high-profile issues plaguing its vessels in recent years, and which is battling companies such as SpaceX for dominance in the space sector.

Boeing kicked off August by announcing it was writing off $US125 million ($190 million) of unplanned costs spent on Starliner, adding to $US1.5 billion ($2.2 billion) of earlier write-offs.