On Saturday (August 24), NASA announced a final decision regarding the fate of the two astronauts aboard the International Space Station whose eight-day space trip turned into a limbo that stretched into several months. Suni Williams and Butch Wilmore, who launched to the ISS on June 5 aboard Boeing’s Starliner spacecraft, will return home no earlier than February 2025.
And NASA and Boeing Decided jointly Williams and Wilmore won’t be returning to Earth in the same Starliner capsule that brought them to the ISS. Instead, they’ll be riding in a SpaceX Dragon capsule for their descent to Earth, a craft purpose-built for the Crew 9 mission, scheduled to launch in September, that will be modified to accommodate Starliner astronauts. The capsule will launch with only a crew of two to make room for Wilmore and Williams to sit during the return to Earth. It will also be reconfigured to carry more cargo, personal items, and Dragon-specific spacesuits for the two Starliners.
Meanwhile, NASA and Boeing plan to return the Starliner spacecraft to Earth unmanned and land it at White Sands Space Harbor in New Mexico sometime in September.
The decision came after considerable uncertainty about when the Starliner astronauts would return to Earth after completing what was called a crewed flight test of the capsule, so named because the journey marks Starliner’s first crewed mission, as opposed to the two previous uncrewed tests.
“The decision to leave Butch and Suni behind on the International Space Station and return the Boeing Starliner uncrewed was driven by a commitment to safety,” NASA Administrator Bill Nelson told reporters on Saturday.
The safety concerns come because the team says there are serious issues with Starliner’s propulsion system, or thrusters. While Starliner’s launch into orbit wasn’t perfect — it was delayed by a small helium leak, for example — it was its docking with the ISS that worried operators the most. Essentially, during docking, the capsule experienced failures in five of its 28 reaction control thrusters. That prompted NASA and Boeing to extend Starliner astronauts’ stay at the ISS to try to fix the problem, but it seems they haven’t found a solution yet.
“We’re dealing with some very complex problems with thrusters,” Steve Stich, NASA’s commercial crew program manager, said at the conference Saturday. “It’s hard to predict how the thrusters will perform, it’s hard to predict the temperatures.”
“One of the really important factors is we don’t know how much of the thrusters we can use on the way back before we run into problems,” Ken Bowersox, NASA’s associate administrator for space operations, said during the meeting, specifically pointing to heating effects that occur “on the way uphill.”
Therefore, because of these uncertainties, NASA stresses that it would be too risky to return Wilmore and Williams to the planet on the Starliner spacecraft that sent them into space.
“If we had had a model – if we had a way to accurately predict how the thrusters would perform from undocking to the deorbit burn to the separation sequence – we would have done things differently,” Stich said. But when the team looked at the data, including numbers on the chances of thruster failure with a crew on board, “the risk was too great.”
Notably, Nelson said he was mindful of NASA’s two deadly space shuttle disasters — Challenger in 1986 and Columbia in 2003, which killed a combined 14 astronauts — when entering the decision-making process, particularly since he was a U.S. senator at the time of the latter disaster.
“No obvious mistakes were made public,” he said of those missions. “Even going back to the loss of Challenger, engineers at Morton Thiokol in Utah were pleading with management to cancel the launch because of the cold, but that information was never made public.”
And in the case of Columbia, the hardware issue wasn’t raised because of a particular culture that fosters this kind of data omission, he said. “NASA has worked hard ever since to create an atmosphere where people are encouraged to come forward and voice their opinions, and I think today is a great example of that.”
On a more positive note, NASA Associate Administrator Jim Freeh said, “NASA and Boeing teams have made great technological advances in building new, more accurate thruster models based on physical thruster testing and an understanding of the associated fluid physics and material properties.”
Of course, the choice to keep Wilmore and Williams on the ISS until February 2025 means they will have to unexpectedly stay aboard the Earth-orbiting station for a total of about eight months, raising questions about how this postponement will affect station operations. However, ISS program manager Dana Weigel said she is not overly stressed about the revised time frame, noting that NASA has previously had astronauts stay on the ISS for about 12 months at a time. Additionally, when it comes to the distribution of supplies, she explained that all astronauts currently aboard the station are healthy and have not needed to be rationed.
So what’s the next step? Well, it’s planning the descent of an unmanned Starliner capsule to Earth, technically called an “unmanned test flight.”
“We’re modifying our planned separation procedure and we’ll be looking at that during the readiness review,” Stich said. “We’re going to use a simplified separation technique to get us away from the station a little bit quicker. We’re going to proceed to the deorbit burn and execute that as planned.”
Asked where Boeing stands on the matter, Bowersox said the vote among all NASA officials was unanimous, but that Boeing executives have expressed a willingness to bring the crew home on Starliner. “They believe in their spacecraft,” he said.
“The mood was, we all wanted to get the crew on board and complete the test flight and I think it was unanimous and disappointing that we couldn’t do that,” he added.
He also spoke about the importance of supporting Boeing’s efforts to ensure the success of Starliner in general, as NASA wants to have multiple options for future crewed flight, whereas currently it relies on SpaceX’s capsules.
“Competition is healthy in many ways,” Bowersox said. “It encourages technological development and drives down prices, and we want to continue that competition.”
Indeed, that’s why NASA awarded Boeing a $4.2 billion contract in 2014 to build capsules for six crewed flights to the ISS. SpaceX was awarded a similar $2.6 billion contract the same year, and has since completed nine such flights with its Dragon capsule. Crew 9 will be the tenth.
So Nelson also asserts that Boeing is 100% confident that Starliner will launch again with crew on board, but will complete all necessary safety testing first.
“We look forward to further identifying root causes and making design improvements to ensure Boeing Starliner remains a vital part of ensuring crew access to the ISS,” Nelson said. “Our core value is safety, it’s our North Star.”
“This was not an easy decision,” Freeh said, “but it is absolutely the right decision.”
Editor’s note: This story was updated Aug. 24 to reflect new information and comments from Boeing’s Aug. 24 press conference on the Starliner crew flight test.
