Confirmed: Boeing Starliner astronauts will return on a SpaceX Crew Dragon

Boeing Starliner astronauts launched to the International Space Station on June 5, 2024, with an anticipated mission of around eight days. They will return to Earth in February of 2025 on a SpaceX Crew Dragon, with a mission length of around 8 months.

Let’s break down what went into this decision, why NASA ultimately decided the risks with Boeing Starliner were too great, what the astronauts might be feeling, and whether I think Boeing Starliner will ever be an operational spacecraft.

How will the return work?

Boeing Starliner will undock autonomously in early September. Chatter has been that the date that’s currently being looked at is September 6, but there hasn’t been anything official — NASA is just maintaining that it will be early September, and there’s a window every four days for Starliner to re-enter. Engineers are currently working on some software configuration changes to allow it to undock autonomously rather than with crew. (A lot of to do is being made about this, but it’s basically just updating what’s called the Mission Data Load to tell it crew won’t be onboard. It takes time because of the immense amount of testing involved with sending anything to a spacecraft.)

NASA is planning on changing the separation procedure, basically to get Starliner away from the ISS more quickly, but the undocking will go normally, as will deorbit and re-entry. Starliner will jettison the troublesome service module before re-entry and then land at White Sands Test Facility.

Crew-9 will launch on a SpaceX Crew Dragon no earlier than September 24 with two crewmembers. We don’t know which two crew members those will be, that announcement will come later. There will be one empty launch and entry suit aboard; NASA has already determined there’s an extra suit aboard the ISS that will fit one of the crewmembers, so only one needs a suit.

Butch and Suni will assume the duties of Crew-9, and they will be on the ISS until the scheduled return date in February 2025.

This sounds like a huge deal. But in terms of spaceflight, mission extensions — even of this length, eight days to eight months, are relatively routine. For example, Frank Rubio spent 371 days on the ISS, finally returning home in September 2023. His mission was extended over six months because of a leaky Soyuz capsule. This specific mission extension is getting a lot of attention because it’s Boeing versus SpaceX.

This was a hard call for NASA to make

It was very interesting to hear from NASA officials that this decision was disappointing. All of them wanted to complete the mission as originally envisioned. But it was also a unanimous decision to bring Butch and Suni home on a SpaceX Crew Dragon instead of Boeing Starliner.

It was incredibly reassuring to me to see the leaders cite the culture that led to the two Space Shuttle tragedies as one of the things they kept front of mind when making the decision for Boeing Starliner. Even Administrator Bill Nelson specifically said that the agency lost two space shuttles as a result of there being a culture where people couldn’t come forward.

I’ve followed the ins and outs of this mission extensively, for years, through the uncrewed test flights way before CFT launched. I do think bringing Butch and Suni home on a SpaceX Crew Dragon is the right decision. Let’s dive into why.

Briefly: There are two problems with Starliner. First are the helium leaks, which have gotten most of the attention. The spacecraft sprung five helium leaks during the period before launch to when it docked with the ISS. However, this hasn’t been a huge concern over the past few weeks.

What NASA and Boeing have specifically been looking at is the thruster failures, which all tie back to overheating. All of these thrusters are located within Boeing Starliner’s service module, which does not come back to Earth.

Starliner has 20 OMAC thrusters and 28 RCS thrusters. The OMAC thrusters are the more powerful ones, orbital maneuvering thrusters, while the RCS thrusters are for smaller adjustments, holding attitude, that sort of things. Starliner needs a combination of both to maneuver in space.

These thrusters are located in what are called doghouses around the capsule. There are four of them, each of which has a thruster pack of 5 OMAC and 7 RCS thrusters. Starliner had issues with thruster failures and low thrust, but the failure itself isn’t the problem. It’s the cause of the failure — overheating in these doghouses. This is what they’ve really been zeroing in on over this past week.

Basically, when the OMAC thrusters fire, the doghouses heat much more than they should, and the other individual thrusters absorb that heat. This, in turn, causes bulging in Teflon seals and vaporization of propellant. That bulging seal reduced the amount of oxidizer getting to the thruster, which was why there was low thrust. Essentially the thrusters weren’t getting enough fuel, and the Teflon was damaged. It was unclear what repeated damage would do.

The bottom line is what the on-the-ground testing at White Sands demonstrated to NASA was that the thrusters were operating in an environment that was hotter than what they were really designed for. And given the heating they encountered before docking with the ISS, it was unclear how these thrusters would act (and whether they would fail) on the return.

Now, Boeing did see some thruster problems on the second uncrewed flight test, OFT-2, but the thrusters have experienced significantly more heating on this crewed flight test. That means the data from the deorbit and re-entry of those flights can’t really apply here because there’s a lot more concern about how the thrusters will behave.

Basically, the question is — will these thrusters fail during the return? It’s possible that with enough testing, Boeing and NASA could have gotten to a point where they were confident that would not happen. But there was a time crunch — NASA wanted to undock Starliner in early December, and it became very clear they would not be able to get a definitive answer by their deadline. So the only option, really, was to return Starliner uncrewed.

Will Boeing Starliner ever fly astronauts again?

What will happen to the Starliner program? That’s not clear.

NASA Administrator Bill Nelson said that he was 100 percent confident that Starliner would launch again with crew on board. Boeing has a new CEO now, Kelly Ortberg, and Senator Nelson made it clear that he’d spoken with Ortberg and both NASA and Boeing continue to be committed to Starliner.

But NASA is working with Boeing on a fixed-price contract. That means NASA paid Boeing for some of the development for Starliner and a certain number of operational flights, but any cost overruns due to schedule delays or anything else are Boeing’s responsibility. Let’s break it down.

In total, NASA has paid almost $3.3 billion to Boeing for Starliner development costs (as compared to around $2.6 billion for SpaceX Crew Dragon). These are numbers from The Planetary Society, through the end of 2023. According to CNBC, Boeing has lost $1.5 billion on Starliner. They have no other customers besides NASA, so there’s not much of a way to recoup that loss with Starliner as it is right now. And given that we’re quickly approaching the end of life of the ISS.

Now, of course it’s possible there will be a life extension for the ISS past 2030. But before this mission, the earliest an operational mission could have been was 2025. Now we’re looking at more like 2026. How many missions can Boeing Starliner realistically fly before there’s nowhere for NASA to go in low Earth orbit?

There are a lot of questions here, but I will say that Administrator Nelson is much more certain of Boeing’s continued participation in Commercial Crew than I am. They’ve lost so much money, and will continue to lose money, especially when you consider that they may have to pay for a second crewed test flight before they can begin operational flights to the ISS.

The language in the Boeing Commercial Crew contract seems to indicate that they do need to return with crew in order for Starliner to be certified for operational flight. NASA has declined to comment on whether they would be able to certify Starliner now that it’s coming back uncrewed. It’s clear they want to.

After NASA’s experience with Shuttle, they do not like only have one way to ferry astronauts to and from low Earth orbit. Given geopolitical tensions, and Russia’s own space program woes, they don’t want to rely on the Soyuz. That means having two separate spacecraft to launch astronauts to and bring them home from low Earth orbit. I cannot emphasize enough how important this is to NASA.

That means that they WANT to have an operational Boeing Starliner. They WANT to certify Boeing Starliner. But CAN they, and is that safe? That’s what they have to determine. They do think at this point that Boeing does have enough information to find mitigations on the thruster issues for future flights. But they will not commit to either certifying Boeing Starliner based on this flight or having a second crewed flight test at this moment, and that’s fair.

Right now they’re focused on bringing the uncrewed Starliner home. But there are still a lot of questions for the future, despite the agency’s current position is that they do wholeheartedly think that Starliner will eventually be an operational spacecraft. (The fact that at that Saturday press conference, Administrator Nelson cited SLS, the boondoggle of a rocket for the Artemis program that is a mess on basically every level, as evidence that Boeing does good work is…not reassuring. I’ll have a deeper look at SLS hopefully later this week).

Don’t forget about Butch and Suni!

Okay, so finally, let’s talk about these astronauts, Butch Wilmore and Suni Williams, who went up anticipating an eight day mission and will now be on the ISS for eight months. How are they doing? I know it’s hard to believe, but…they’re fine. I’ve seen this mission extension likened to getting stuck somewhere during travel but astronauts actually expect this sort of thing.

I’m sure they have feelings about it. I’m sure their have families have feelings about it. But also, this is the job and life of a NASA astronaut. Mission extensions are absolutely a normal part of the job. They’ve trained for all kinds of contingencies, and this is just one of them.

As far as health? We know what up to about 13 months on the ISS will do to the human body. They will be on the ISS for a shorter period of time than that. The agency is very interested in how long duration spaceflights affect astronauts, but also have done a lot of work at mitigating that. For example, Butch and Suni are doing 2 to 3 hours of exercise a day, minimum, while up there. Normal ISS assignments are for six months, theirs will be just a couple of months longer than that.

The ISS also carries about a four month extra supply of consumables. There are also regular resupply missions (there was just one a couple of weeks ago that launched on August 4.) When the agency realized that it was a possibility that Butch and Suni would extend their stay, they opted to add extra consumables to that flight. These resupply missions happen at regular intervals, so don’t worry about anyone going hungry.

It’s been a long few months, probably even longer for Butch and Suni, and I’m guessing there’s some relief finally having some certainty about how and when they’ll come home.