CAPE CANAVERAL, Fla. (AP) — NASA decided Saturday that it was too risky to return two astronauts to Earth in Boeing’s new, troubled capsule. They will have to wait until next year for a flight home with SpaceX. What was supposed to be a one-week test flight for the couple will now take more than eight months.

The experienced pilots have been stuck in the International Space Station since the beginning of June. A cascade of annoying engines Failures and helium leaks in the new capsule marred their journey to the space station, and they ended up in a holding pattern while engineers conducted tests and discussed what to do about the return flight?

After nearly three months, the decision finally came from NASA’s highest ranks on Saturday. Butch Wilmore and Suni Williams will return in a SpaceX capsule in February. Their empty Starliner capsule will undock in early September and attempt to return with an autopilot landing in the New Mexico desert.

As test pilots of the Starliner, the two were supposed to monitor this critical final leg of the journey.

“A test flight is by nature neither safe nor routine,” said NASA Administrator Bill Nelson. The decision was “the result of a commitment to safety.”

Nelson said lessons from NASA’s two space shuttle accidents played a role. This time, he noted, open dialogue was encouraged rather than stifled.

“This was not an easy decision, but it is absolutely the right one,” added Jim Free, NASA’s deputy administrator.

It was a major blow to Boeing, adding to the company’s aircraft safety concerns. Boeing had been banking on Starliner’s first crewed flight to revive the troubled spacecraft program after years of delays and spiraling costs. The company had insisted that Starliner was safe both in space and on the ground based on all of its recent engine tests.

Boeing did not attend NASA’s press conference on Saturday, but issued a statement: “Boeing remains primarily focused on crew and spacecraft safety.” The company said it was preparing the spacecraft “for a safe and successful return.”

Rand Corp.’s Jan Osburg, a senior engineer specializing in aerospace and defense, said NASA made the right choice. “But the U.S. still faces embarrassment because there are problems with the Starliner design that should have been identified earlier.”

Wilmore, 61, and Williams, 58, are both retired Navy captains with extensive experience in spaceflight. Before their June 5 launch from Cape Canaveral, Wilmore and Williams said their families accepted the uncertainty and stress of their careers decades ago.

During their lonely orbital press conference Last month, the astronauts said they had confidence in the engine tests being conducted. They had no complaints, they added, and they enjoyed helping with the work on the space station.

Wilmore’s wife, Deanna, was equally stoic in an interview with WVLT-TV in Knoxville, Tennessee, her home state, earlier this month. She was already prepared for a delay: “You just have to kind of accept it.”

Flight operations manager Norm Knight said he spoke to the astronauts on Saturday and they fully supported the decision to delay their return.

There were few options.

The SpaceX capsule currently parked at the space station is reserved for the four residents who have been there since March. They will return in late September, their routine six-month stay extended by a month by the Starliner dilemma. NASA said it would be too dangerous to squeeze two more into the capsule except in an emergency.

The docked Russian Soyuz capsule is even more cramped, as it can only carry three passengers – two of them Russians who are currently completing their one-year mission.

Wilmore and Williams will have to wait for SpaceX’s next taxi flight, which is scheduled to launch at the end of September with two astronauts instead of the usual four. NASA is taking two astronauts off to make room for Wilmore and Williams on the return flight at the end of February.

According to NASA, asking SpaceX for a quick, independent rescue was not seriously considered. Last year, the Russian space agency had to Replacement Soyuz capsule for three men whose original spacecraft was damaged by space debris. The change extended their six-month mission to just over a year.

Former Canadian astronaut Chris Hadfield praised the decision via X: “It’s good to play it safe to protect the lives of astronauts.” Long missions are “what astronauts work for their entire careers. I would take it in a heartbeat!”

The Starliner’s problems began long before its last flight.

The first uncrewed test flight in 2019 was disrupted by faulty software, requiring a repeat in 2022. Then problems arose with the parachute and other issues, including a helium leak in the capsule’s fuel system, which prevented a launch attempt in May. The leak was eventually deemed isolated and small enough not to be a concern. But more leaks appeared after launch, and five engines also failed.

All but one of the small engines restarted in flight. But engineers were baffled when ground tests showed that an engine seal had swelled and blocked a fuel line. They suspected that the seals might have expanded in orbit and then returned to their normal size. Officials said the results marked a turning point, and their concerns grew.

Given the uncertainty about engine performance, “the risk to the crew was too great,” Steve Stich, NASA’s commercial crew program manager, told reporters.

These 28 engines are vital. Not only are they needed for the rendezvous with the space station, but they also keep the capsule pointing in the right direction at the end of the flight while larger engines steer the spacecraft out of orbit. Misalignment could result in disaster.

The Columbia disaster is still fresh in many minds – the space shuttle broke apart during re-entry into the Earth’s atmosphere in 2003, killing all seven people on board – and so NASA made a special effort to facilitate an open debate about the Starliner’s ability to return.

Despite Saturday’s decision, NASA is not giving up on Boeing. Nelson said he is “100%” confident Starliner will fly again.

A decade ago, NASA launched its commercial crew program with the goal of contracting two competing U.S. companies to transport astronauts in the post-shuttle era. Boeing won the larger contract: over $4 billion, while SpaceX won $2.6 billion.

SpaceX has already completed supply flights to the station and successfully completed its first of now nine astronaut flights in 2020, while Boeing has been mired in design flaws that have cost the company more than a billion dollars. NASA officials still hope the Starliner’s problems can be fixed in time for another crewed flight in about a year.

___

The Associated Press Health and Science Department receives support from the Science and Educational Media Group of the Howard Hughes Medical Institute. All content is the responsibility of the AP.