(CNN)– A SpaceX Crew Dragon capsule will bring home two NASA astronauts who have been stuck aboard the International Space Station for more than 80 days because of problems affecting the Boeing Starliner spacecraft, marking a surprising turnaround for the troubled aerospace giant.
The news comes after the US space agency conducted a formal review on Saturday to determine whether it would consider Boeing's Starliner vehicle safe enough to return home with its crew, or whether SpaceX's Crew Dragon spacecraft would have to step in to save the day.
The Starliner vehicle, which carried astronauts Suni Williams and Butch Wilmore to the space station in early June, suffered setbacks with helium leaks and thrusters that abruptly stopped working in the initial leg of its first crewed test flight. Engineers spent weeks trying to better understand the problems, and Boeing said Aug. 2 that its “confidence remains high” that the spacecraft would be able to return Williams and Wilmore to Earth.
However, NASA revealed during an Aug. 7 briefing that discussions within the space agency over the safety of the Starliner capsule had evolved, leading the federal agency to more seriously consider bringing astronauts home on a SpaceX Crew Dragon vehicle, which has flown on a dozen crewed missions to space since 2020.
On Saturday, Nelson said NASA considered its extensive experience with spaceflight, both successful and unsuccessful, in making the decision.
“We’ve made mistakes in the past — we lost two space shuttles as a result of not having a culture where information could be presented,” Nelson said. “Spaceflight is risky, even at its safest and even at its most routine. And a test flight, by its nature, is neither safe nor routine.”
SpaceX was already scheduled to fly a routine mission to the International Space Station, carrying four astronauts as part of standard crew rotations aboard the orbiting laboratory. But the mission, dubbed Crew-9, could now be reconfigured to carry two astronauts instead of four.
That adjustment would leave two empty seats for Williams and Wilmore to fill on the Crew-9 flight home. The astronauts would also officially join the Crew-9 team, becoming part of the official expedition. With that transition, Williams and Wilmore would remain in situ for six more months — the length of a routine mission to the space station.
Reassignment to Crew-9 could delay the duo's return until February 2025 at the earliest.
In that case, Starliner would return home empty. And NASA would have to decide whether the data Starliner collected on its mission is sufficient to give the space agency the confidence to officially certify Starliner for human spaceflight, a step that would prepare the vehicle to make routine trips to orbit.
Five of Starliner’s 28 “reaction control thrusters” failed to function during the first leg of Boeing’s test mission. All but one were eventually recovered.
And although Williams and Wilmore had expected to spend just eight days in space, their stay aboard the orbiting laboratory has now been extended to about two months as engineers on the ground have worked to better understand the thruster problems.
The officials explained that they were able to recreate with ground tests how the propellants deteriorated in space during the flight. According to Boeing, the possible cause is the accumulation of heat inside the propellants, which may be causing the insulating seals to bulge and restricting the flow of propellant.
The helium leak problems, on the other hand, may be due to seals degrading due to exposure to propellant vapor, Mark Nappi, director of Boeing's Commercial Crew program, said July 25.
However, NASA has struggled to reach a consensus on how these problems could affect astronauts' return to space and what level of risk they would pose.
Uncertainty over the level of risk is why the agency may turn to SpaceX and its Crew Dragon spacecraft to step in.
NASA has repeatedly said that the potential for SpaceX to step in underscores how the space agency intentionally designed its Commercial Crew Program — under which both Starliner and Crew Dragon were developed — to allow each spacecraft to serve as a backup to the other.
“We’re kind of in a new situation here and we have multiple options,” Ken Bowersox, associate administrator for NASA’s Space Operations Mission Directorate, said Aug. 7. “It’s something we’ll have to deal with in the future — we might find ourselves in a situation where we need to bring a[SpaceX]Dragon crew or a[Russian]Soyuz crew back on a Starliner.”
“That’s why we want multiple vehicles, to have that option,” Bowersox added.
Still, the federal agency funded SpaceX's Crew Dragon and Boeing's Starliner at the same time in 2014. Crew Dragon has been operational for four years, while the Starliner program is hundreds of millions of dollars over budget and years behind schedule.
Boeing's development process has also been plagued by errors.
For example, Starliner’s first test mission, flown uncrewed in 2019, failed in orbit, cutting the flight short far earlier than expected. The vehicle ultimately failed to dock with the space station as planned, and the result was revealed to be a symptom of a myriad of software issues, including a coding error that set an internal clock back 11 hours.
A second uncrewed flight test in May 2022 uncovered additional software issues, and mission teams addressed problems with some of the vehicle's thrusters. However, the root cause of the thruster problem affecting this crewed mission was overlooked two years ago.
The question of whether the Starliner vehicle will finally be certified after its return to Earth is likely to become a contentious issue, which is considered the most dangerous stage of the mission. The autonomous vehicle will have to use its thrusters to precisely orient itself as it plunges back into Earth's thick atmosphere. The pressure and friction are expected to heat the vehicle's exterior to about 1,650°C.
Starliner's parachutes must deploy smoothly and slow the spacecraft before activating the airbags to expand and cushion the landing.
If the Starliner capsule is ultimately certified, it could join SpaceX's Crew Dragon on routine trips to the space station to rotate crew. Currently, those trips take place about every six months.
And if the spacecraft is denied certification, it would mark yet another blow to Boeing’s already badly damaged reputation. Failing to meet the goal could cost the company many millions of additional dollars, on top of the roughly $1.5 billion the company has already recorded in losses on the Starliner program.
