Here's when NASA's Starliner astronauts will finally come home – and how

It was supposed to be a weeklong test flight. Butch Wilmore and Suni Williams planned to fly Boeing’s new Starliner capsule to the space station, put it through its paces in orbit, and return with a historic landing in New Mexico.

That was back in June.

Since then, the duo has waited and the world has watched while Boeing tried to understand why the capsule experienced helium leaks and, more problematically, why some of the craft’s steering thrusters weren’t working.

Now, NASA says it’s too risky to let Wilmore and Williams try flying home on Starliner, so they’ll instead catch a ride aboard a SpaceX Dragon capsule early next year. They’ll be safe on the space station until then.

Meanwhile, the Starliner capsule will undock on its own and make an automated return to Earth.

File: NASA's Boeing Crew Flight Test astronauts (from top) Butch Wilmore and Suni Williams pose for a portrait inside the vestibule between the forward port on the International Space Station's Harmony module and Boeing's Starliner spacecraft, June 2

What is wrong with Starliner?

Starliner’s launch on June 5 – which was already years behind schedule – was delayed by a helium leak that engineers ultimately decided was minor enough that they could fly. But after the capsule blasted off, four more helium leaks popped up. 

Boeing said the leaks were "stable" and, on their own, would not stop the craft from completing its mission.

Then, five of the capsule’s 28 thrusters failed as the capsule closed in on the space station. All but one of them ultimately came back to life, but NASA opted to keep the astronauts at the space station while engineers tested the thrusters in space and also studied versions of them back on Earth.

File: Boeing's Starliner spacecraft that launched NASA's Crew Flight Test is pictured docked to the Harmony module's forward port. This long-duration photograph was taken on July 3, 2024 from the orbital complex as it soared 258 miles above western C

Until NASA and Boeing understand why the thrusters failed, there’s a chance they could fail again as the astronauts perform the precise positioning needed to safely reenter the atmosphere and land.

That chance is evidently too high for NASA. Administrator Bill Nelson said, after a series of high-level meetings Saturday, that the agency felt it was not worth the risk to send the astronauts back home aboard Starliner.

"Spaceflight is risky, even at its safest, and even at its most routine. And a test flight, by nature, is neither safe nor routine," Nelson said Saturday, citing lessons learned from the Challenger and Columbia accidents. "And so the decision to keep Butch and Sunday aboard the International Space Station and bring the Boeing's Starliner home uncrewed is a result of a commitment to safety."

"There was just too much uncertainty in the prediction of the thrusters," NASA Commercial Crew Program Manager Steve Stich explained. "If we had a model, if we had a way to accurately predict what the thrusters would do for the undock and all the way through the deorbit burn and through the separation sequence, I think we would have taken a different course of action. But when we looked at the data and looked at the potential for thruster failures with a crew on board…It was just too much risk with the crew."

Why do the astronauts have to wait?

In short, they are waiting for their ride as NASA and its partners shuffle crews around. 

SpaceX’s Dragon capsule is configured to carry four people. Four astronauts were due to launch on the Crew 9 mission this month, but NASA will delay that launch so they can send only two astronauts, leaving two seats open for Wilmore and Williams when that mission’s rotation ends, likely in February.

File: The seven Expedition 71 crew members gather with the two Crew Flight Test members for a team portrait aboard the space station. In the front from left are, Suni Williams, Oleg Kononenko, and Butch Wilmore. Second row from left are, Alexander Gr

"I talked with Butch and Sunny, both yesterday and today. They support the agency's decision fully, and they're ready to continue this mission on board ISS as members of the Expedition 71 crew," NASA Flight Operations Director Norman Knight said. 

Wilmore and Williams also have to wait for SpaceX flight suits to be launched with the Crew 9 mission; their Boeing suits are not compatible with the life support systems on SpaceX’s capsule.

What does this mean for Boeing and Starliner?

It’s not yet clear. For its part, Boeing has said Starliner is safe and its engineers feel it could carry Wilmore and Williams home, but the company will abide by NASA's decision.

"I have just talked to the new Boeing CEO, Kelly Berg. I have expressed this to him: I told him how well Boeing worked with our team to come to this decision. And, he expressed to me an intention that they will continue to work the problems once Starliner is back safely and that we will have our redundancy and our crewed access to the space station," Administrator Nelson offered.

Boeing hoped that this test flight would be sufficient for NASA to certify the Starliner as ready for regular missions. Indeed, NASA would prefer to have two different space taxis so that its astronauts would not be stranded if something were to happen to one of the capsules. 

But Boeing’s next steps are not certain – the delays have already cost the company $1 billion – and plans may not be clear until Starliner is back on Earth and the full mission can be evaluated.

File: The SpaceX Crew Dragon Endeavour carrying four commercial crew astronauts departs the International Space Station in November of 2021. (NASA)

Meanwhile, Boeing will seemingly suffer the ignominy of being bailed out by rival SpaceX – the latest setback for a company already struggling with well publicized issues in its commercial airliner division.

Boeing did not have a representative at Saturday's press conference, but they issued a statement soonafter. "We continue, first and foremost, on the safety of the crew and the spacecraft. We are executing the mission as determined by NASA, and we are preparing the spacecraft for a safe and successful uncrewed return."