Starliner: Two NASA astronauts may be stuck on the space station until February

NASA astronauts Butch Wilmore and Sunita Williams may be stuck on the International Space Station (ISS) until February 2025 after issues cropped up with the spacecraft they rode to the station. This was the first crewed test flight of that capsule, Boeing’s Starliner, and it is not yet clear whether it will be safe for Wilmore and Williams to use it to get home.

Starliner launched on 5 June, with the intention of spending about a week docked to the ISS before shuttling the astronauts back to Earth. The launch had been delayed by a myriad of small problems with the spacecraft, and even on the day of lift-off the craft experienced minor helium leaks that engineers decided were not enough of a problem for another delay.

But by the time it reached the ISS, more helium leaks had sprung and five of Starliner’s 28 thrusters had failed. Wilmore and Williams boarded the ISS safely – but it is now a month beyond their planned return to Earth, and the next move is uncertain.

“When we started this mission, it was a test mission,” said Ken Bowersox at NASA during a 7 August press conference. “We knew that it potentially had a higher risk than a flight on a vehicle that has more experience.” Now, he says there are disagreements within NASA as to whether the risk of more leaks and thruster failure during a return flight is too high to put people back on board Starliner.

A major part of assessing that risk has been attempting to recreate the issues that Starliner has seen in space with tests on the ground, said NASA’s Steve Stich during the press conference. He said there has been some progress, but not yet enough to significantly lower the uncertainty in how Starliner will perform on its way back to Earth. “We can’t totally prove with certainty [that] what we’re seeing on orbit is exactly what we’re seeing on the ground,” said Stich.

Of course, this does not mean that Wilmore and Williams will be stuck aboard the ISS forever – there are contingency plans. If NASA does decide that the risks with Starliner are too high, Starliner’s software will have to be reconfigured for an autonomous, uncrewed return to Earth. Then, the SpaceX Crew Dragon capsule currently docked to the ISS will be reconfigured to carry two extra astronauts.

But that isn’t the main option. There is another plan to bring the astronauts home using the next Crew Dragon that is launched. The date for that launch was just delayed to September – it was originally intended to carry four astronauts to the ISS, but it may carry only two, leaving room for Wilmore and Williams when the mission is over in February 2025.

Wilmore and Williams are trained to perform all of the planned activities for that mission, including spacewalks, but this plan would extend their stay in space from the scheduled eight days to nearly eight months. NASA has already directed SpaceX and Boeing to start working on the updates needed to make either plan happen, but a choice has not been made yet.

“Those are backup contingency plans,” said ISS manager Dana Weigel at the press conference. “We have not made any decisions at all in terms of anchoring to a specific plan.” Stich said that a decision is likely to be made in mid-August. The greater impacts of this struggle on NASA’s Commercial Crew Program remain to be seen.