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As NASA announced today, Boeing Starliner will return to earth uncrewed and before the SpaceX Crew-9 mission will start (because otherwise no docking port would be available).

This means (as far as I understand it) that between the departure of Starliner and the arrival of the Dragon capsule of the Crew-9 flight, Butch Wilmore and Suni Williams will have no seat in a spacecraft in case of an emergency on the ISS during that time.

In the past, great effort was put into making sure that there were never more astronauts aboard the ISS than there were seats available in docked spacecraft. (Is this true for the shuttle era too?) So when a capsule had to park on another docking port, the whole crew of that spacecraft went into the capsule, even if it was not technically necessary, in case the capsule could not dock again for some reason, which would leave a person "stranded" on the ISS.

Is this the first time that astronauts are aboard the ISS without a seat in a docked spacecraft?

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    $\begingroup$ Possibly out of date, but the answers to this question "has there ever not been the capacity for a full evacuation?" space.stackexchange.com/q/27793/40489 seem to indicate that yes, this might be a first. $\endgroup$
    – blobbymcblobby
    Commented Aug 24 at 21:12
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    $\begingroup$ This is quite a development, although not unexpected. $\endgroup$
    – Organic Marble
    Commented Aug 24 at 21:22
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    $\begingroup$ "Is this true for the shuttle era too?" In terms of regular missions yes, but not necessarily in emergencies. Most notably the 3xx missions would've had the entire crew of a damaged Shuttle cooling their heels on the station for a month and a half with no lifeboat capacity. (Except, I suppose, taking their chances with the orbiter that brought them there.) $\endgroup$
    – Cadence
    Commented Aug 25 at 4:26
  • $\begingroup$ @Cadence - it seems like redundancy in return options has not been a priority throughout the history of human spaceflight. Although discussed occasionally in the past, It doesn't seem to have become a widely discussed topic until after the Columbia accident. But still the emphasis seems to mainly be making sure that everyone has a nominal method of return available for off-nominal problems at the station or a medical emergency. But problems with a lifeboat, or planning for potential problems with lifeboats, seems to be currently managed on an ad hoc basis, resulting in sub-optimal solutions. $\endgroup$
    – Steve Pemberton
    Commented Aug 26 at 17:23

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Technically, no. Depending on how literal you interpret the term "seat", this will either be the second time or the premise of the question is wrong, since there are, in fact, enough seats.

So, it will be either the second or "zeroth" time, but not the first.

tl;dr

In some sense it has happened before that an astronaut had no seat in a lifeboat available, but in another sense, it is actually not true that Butch and Suni don't have seats available.

Soyuz MS-22

There was an interesting situation in 2023 where the lifeboat rules were tested: the Soyuz MS-22 capsule had sprung a leak in its coolant system, and there was concern that the astronauts would be subjected to high temperatures during the return flight. Therefore, it was decided to push the Soyuz MS-23 mission forward and turn it into an uncrewed mission.

However, this meant that cosmonauts Sergey Prokopyev and Dmitry Petelin, and astronaut Frank Rubio would have had no lifeboat for two months until the arrival of Soyuz MS-23.

NASA decided that Frank Rubio's seat liner would be un-installed from Soyuz MS-22 and jerry-rigged into Crew-5's capsule Endurance. While Crew Dragon always flies with a crew of at most 4, it was originally designed for 7, therefore, its environmental control and life-support systems would easily be able to handle a crew of 5; this also means there is enough space on the cargo pallet behind the four seats, where the other three seats would have been. Crew Dragon's water landing is fairly benign, so not having a proper seat for Frank Rubio was deemed acceptable – remember, we are only talking about an emergency return, where different Flight Rules apply and NASA is willing to accept more risk.

Roskosmos decided that Soyuz MS-22 was probably safe enough for an emergency return, especially with the reduced heat load of only 2 cosmonauts, so it served as lifeboat for Sergey Prokopyev and Dmitry Petelin.

In the end, none of that was needed. After the arrival of Soyuz MS-23, the three seat liners were moved from Endurance and Soyuz MS-22 to Soyuz MS-23, at which point, the normal lifeboat situation was re-established.

Soyuz MS-22 returned uncrewed. To make its return as easy and fast as possible, the ISS was pitched 90° and the Soyuz's thrusters were fired longer than normal, reducing the return journey to only 55 minutes. The temperature reached 50°C, which was lower than the worst-case estimates, and would have been survivable.

Starliner

NASA already did all the relevant studies back in 2023. So, they know that they can, if needed, use the cargo pallet of Crew Dragon to transport additional astronauts. The major difference between the MS-22 situation and now, is that Frank Rubio had a Sokol flight suit and a Soyuz seat liner whereas Butch Wilmore and Suni Williams have Boeing flight suits. If I understood Steve Stich correctly during the press conference, there is already a spare SpaceX Crew Dragon flight suit on the ISS which fits at least one of the two astronauts. However, I believe there are no additional umbilical ports except those in the armrests of the seats, so there would be no way to connect the suit to the environmental control and communications systems.

In addition, NASA has already cleared Starliner for use in an emergency back in June.

So, while Starliner is still docked to the ISS, it can serve as a lifeboat for Butch and Suni. After it undocks, Crew-8's Crew Dragon Endurance will serve as the lifeboat.

Technically, Butch and Suni will indeed not have "seats" in the literal sense of the word. But they will have a place to shelter and an emergency return vehicle, so they will have "seats" in the metaphorical sense of the word.

Why is Starliner both safe and unsafe?

It may be a bit confusing why Starliner is deemed unsafe for a return flight, but safe for an emergency return flight. The reason is that the two situations have different risk assessments:

  • In an emergency situation, the choice is between almost certain death on the ISS vs. the relatively small possibility that the thrusters fail during the reentry sequence.
  • In the nominal situation, the choice is between a slightly uncomfortable ride vs. the possibility that the thrusters fail during the reentry sequence.

The press conference

There is a lot of in-depth information in the press conference, most of it in language that can be understood by an interested amateur:

NASA’s Boeing Crew Flight Test Status News Conference

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    $\begingroup$ minor nitpick: "the cargo compartment of Crew Dragon" is the same compartment as the crew compartment. It's the space behind the seats, where seats were originally meant to go but is now typically used for cargo. I think that's actually a common linguistic thing--I used to refer to the area behind the back seats of my Honda Element as the trunk even though it wasn't sectioned off $\endgroup$
    – Erin Anne
    Commented Aug 24 at 23:50
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    $\begingroup$ But they still need to get SpaceX flightsuits to ISS for Butch an Suni for the regular return in February 2025. But for an emergency, the Boeing suits would be good enough? So is it mostly a comfort issue not having the proper Suit? $\endgroup$
    – TrySCE2AUX
    Commented Aug 25 at 7:19
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    $\begingroup$ @TrySCE2AUX - there would be no way to connect the umbilicals for air (and thus pressurization) so the Boeing suits would essentially be useless. This was the same problem Frank Rubio would have had on Crew 5. I actually wondered back then if there are discussions going on about the possibility of having adapters on board for this type of contingency, especially now as this is the second time this situation has occurred. Side note they only have to get one SpaceX spacesuit brought up on the Crew 9 capsule because there is already a spare one on board. $\endgroup$
    – Steve Pemberton
    Commented Aug 25 at 11:59
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    $\begingroup$ @StevePemberton: I was thinking about this as well, but AFAIK, the only ports are in the armrests of the seats, so there would be no way to connect them anyway. They can only be connected if there are seats available, which means sending a new capsule, which means you can also send suits. Normally, astronauts are laser-scanned when they are fitted with a Dragon suit, but there should be plenty of measurements available from the pre-flight medical checks, and I am willing to bet Boeing has measured them as well. $\endgroup$
    – Jörg W Mittag
    Commented Aug 25 at 12:19
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    $\begingroup$ @JörgWMittag Actually, the intention is that, if they have to return on Crew 8 in an emergency, they do it without flight suits. Because without the active cooling provided by the umbilical, they're worse than useless - they'll be cooking the occupants. $\endgroup$
    – Simon Geard
    Commented Aug 25 at 23:23

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