The two astronauts of the Boeing Starliner knew to expect the unexpected when they lifted off on June 5 on the spacecraft's first manned mission.
I learned this back in March, when NASA received reporters at the agency Johnson Space Center (JSC) in Houston for two days. We used four Starliner simulators, spoke extensively with senior agency and Boeing leadership and spoke with NASA astronauts Butch Wilmore and Suni Williams.
The duo - professional astronauts and long-serving veterans International Space Station (ISS) missions - were both U.S. Navy test pilots when they started and knew how to build space programs with large teams decades ago. That's why they were selected to put Starliner through its paces for the first time.
"On an experimental spacecraft, there are things that haven't been done before. We really want to make sure that everything works and that it's good," Williams said in an interview with a small group at JSC on March 24. She explained that dynamic events like docking and manual flight would be especially tricky despite all the simulator hours: "The hairs on the back of our necks stand up a little bit more when we're doing those kinds of things."
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That prediction came true on June 6 - the day after launch - when Williams and Wilmore were asked to delay their final approach to the ISS for docking. Not only was Starliner leaking helium, continuing a manageable problem that had been carefully monitored before launch, but its thrusters were also being affected in ways that NASA and Boeing could not yet explain. The astronauts docked safely with the ISS on their second attempt on June 6, having again demonstrated that they could safely operate the spacecraft.
Starliner has remained at the ISS. The mission, known as Crew Flight Test (CFT), was extended beyond its nominal 10-day timeline, and then extended again beyond 45 days when the batteries (the main limiting factor) performed better than expected. Williams and Wilmore have now spent about 55 days in room living off an existing supply of food, oxygen and other essentials that NASA already has on hand for such scenarios.
Some reporters began calling the astronauts "stranded" or "stuck" on the ISS. NASA and Boeing, however, insist that this couldn't be further from the truth.
"Our plan is to get them back on the Starliner and bring them home at the right time," Steve Stich, manager of NASA's Commercial Crew Program, told reporters at a tense press conference on June 28. (Reporters at the briefing complained that the lack of updates had led to misinformation online; NASA and Boeing promised to meet more often but said they had remained relatively quiet, largely because they were busy troubleshooting Starliner.)
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"We still have some work to do to get there for the eventual return. But they are safe on the space station," Stich said of Williams and Wilmore. "Their spacecraft is working well and they are enjoying their time on the space station."
Boeing's Mark Nappi, who manages the company's commercial crew program, stressed that staying docked at the ISS is the best way to solve problems. "We don't understand problems well enough to solve them permanently, and the only way we can do that is to take the time in this unique environment and collect more data and do more testing," he said in the same press conference.
Starliner was always intended to leave the ISS in case of emergency, and that scenario was activated on June 26 when pieces of Russian satellite space debris entered the mile-wide "pizza box" shape of space surrounding the ISS. Even if the risk to astronauts is infinitesimal, protocol dictates that the crew prepare to go home if an object enters the pizza box.
As per procedures, NASA and the Russian space agency Rose Quartz each instructed their astronauts to shelter in their return spaceshipThe crew of Expedition 71 left for a SpaceX Crew Dragon, a Russian Soyuz and - in the case of Williams and Wilmore - Starliner. They waited for about an hour and were cleared to return to ISS duties when the danger had passed.
"We were ready to execute if they needed an emergency disconnection [for] landing," Stich said. So "It was a great learning experience for us, while we were docked at the space station, to see this eventuality come up. Obviously, we don't like it. space debris situations, but it was great to practice that."
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The reason for Williams and Wilmore's delayed departure isn't really about CFT. While safety is always a topic of discussion, NASA and Boeing have also said they want to understand the root causes of the booster problems and helium leaks while an active spacecraft is still on the ISS. If the astronauts leave, engineers lose the opportunity to not only observe the spacecraft's behavior, but also to use the service module that houses the propulsion system.
The service module will be discarded during landing, and as such, working with it on the ISS will help engineers evaluate how to redesign Starliner or change operations for future ISS missions that are slated to last six months. Starliner-1, that first operational attempt with three astronauts on board, was recently delayed until around August 2025 (from earlier this year) to allow more time for these decisions in the future.
Meanwhile, with space tests inconclusive, NASA and Boeing conducted thrust tests at the White Sands Test Facility in New Mexico earlier this month and discovered some new things.
The 28 thrusters of Starliner's reaction control system (RCS) are housed in insulated shelters called "doghouses." Firing the RCS thrusters repeatedly into space, especially in conjunction with the orbital maneuvering and control system (OMCS), heats the doghouses to levels never seen by engineers on the ground. This causes the insulation in the thrusters to bulge and shed Teflon, restricting propulsion flow and likely explaining why the thrusters malfunctioned during docking last month.
The helium leaks are still being investigated, but NASA has repeatedly said that all spacecraft have experienced this - Dragon and the venerable spaceship included. They even started with these problems.
On Saturday (July 27), NASA and Boeing conducted another hot fire on Starliner's propulsion system in space. From the ground, mission team members took command of 27 of the 28 thrusters. (One was identified weeks ago as being incapable of functioning properly for the return trip.) Early indications are that those 27 met specifications, and NASA is now considering the results in an agency-level CFT review.
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While it's not certain that Starliner will be back home anytime soon, there haven't been any showstoppers during the tests. NASA and Boeing remain cautious, both stressing that safety must come first in any decision to return. There is a backup for the Starliner astronauts: a ride back to Earth on a Dragon. When asked about it by reporters during press conferences, both Boeing and NASA said that Dragon is not needed for this purpose at this time.
Williams and Wilmore always had confidence that the right choices would be made for their safety and the mission as a whole.
"Everything is in place, as far as we know right now," Wilmore said from space July 10, as a round of testing at White Sands concluded. "We're going to learn from that and we're going to implement new processes and procedures that we'll use as needed."
Assuming (as has been the case thus far) that Starliner is cleared to return home, Wilmore said he and Williams "will be ready then, unless the data shows otherwise. But right now, based on what we know, we are absolutely ready."
