Butch Wilmore and Suni Williams have been stuck on the International Space Station (ISS) since 6 June. They were only supposed to stay on the station for about a week, but problems with Boeing’s space capsule, Starliner, have prolonged their space stay for much longer than intended.
The Starliner previously docked to the ISS in 2022 and successfully landed back on Earth in an uncrewed mission. The crewed mission, first foreseen for the beginning of last year, was postponed to “no earlier than Friday, July 21st” 2023”, then a launch scheduled on 6 May this year was aborted due to leaks and thruster issues, then a 1 July launch did not happen, until it finally reached the ISS on 6 June.
Although Wilmore and Williams made it to the ISS, it was far from a smooth ride. Three helium leaks were discovered after the Starliner reached orbit. While one of them was already known before take-off and was considered within acceptable risk, before starting their “sleep period” at night, Wilmore and Williams were notified they had to close off two helium valves to prevent further leaking. Five thruster issues were also still present on the craft.
The two were supposed to only stay on the ISS for about 8 days, maybe 10, with the Starliner remaining docked to the station, then come back to Earth on the same shuttle. The point of the mission was to test Starliner’s performance and its ability to reach the Space Station and return down to Earth. Today, 30 July, is the astronauts’ 55th day in space.
VIDEO: A pair of US astronauts stranded on the International Space Station say they're confident that the problem-plagued Boeing Starliner they rode up on would soon bring them home, even as significant uncertainties remain. pic.twitter.com/ToNiAu0DrM
— AFP News Agency (@AFP) July 12, 2024
While the exact duration of the mission was not precise from the very beginning, Boeing is now saying that they in fact expected it to run longer. “We kept saying ‘eight-day minimum mission.’ I think we all knew that it was going to go longer than that. We didn’t spend a lot of time talking about how much longer”, Mark Nappi, the vice president and program manager of Commercial Crew Program efforts at Boeing, said in a briefing on 25 July. “It’s my regret that we didn’t just say, ‘We’re going to stay up there until we get everything done that we want to go do’”
The Starliner was funded by NASA’s Commercial Crew Programme. Both NASA and Boeing have been running tests since June to try and recreate the issue with the thrusters and simulate a safe return of the astronauts. In July on-ground testing, they discovered that the combination of repeatedly firing the thrusters with the orbital manoeuvring and control system (OMAC) lead to the overheating of the thrusters which, in turn, lead to losing some of their Teflon insulation. The two said the issue couldn’t have been detected before launch.
In the latest update, from 27 July, following a docked test, Boeing said that “all thrusters performed at peak thrust rating values, ranging from 97-102%”. Additionally, the helium system also remained stable, while “an RCS oxidizer isolation valve that was not fully seated previously, was cycled several times during today’s testing and is now operating normally.”
Meanwhile, NASA’s Commercial Crew Program manager, Steve Stich, has indicated they have contingency plans available should Starliner ultimately fail. Elon Musk’s SpaceX is part of the same program, but, as the billionaire pointed out in May, his Crew Dragon spaceship was ready 4 years ahead of Boeing’s, and has since successfully concluded 8 crewed missions for NASA and another 3 for Axiom Space.
“We have two different systems that we’re flying. Obviously, the backup option is to use a different system”, Stich said at a press briefing on 25 July, referring to SpaceX. “I would rather not go into all those details until we get to that time, if we ever get to that time. (…) But right now we’re really focused on bringing Butch and Suni home on Starliner.”
Now, with the systems seemingly in order, without giving a precise date, Boeing said “opportunities are available throughout August” for the return journey. However, considering Starliner’s history of troubleshooting and delays, it remains to be seen whether or not Wilmore and Williams will indeed return home in August.