[JanSolo]

Soyuz is used as a return capsule for 3 of the crew. One of them becoming unavailable is a big problem if there's an emergency on the station and they need to get the crew out fast.

Mission Controllers have only a few options here:

1. If they determine what the problem is and that the leak will not affect Soyuz's ability to return safely, then they can stay on board and continue as normal. This is unlikely; Spacecraft are not supposed to leak 'substances' like this. They also do not carry 'substances' that are not critical to the mission.

2. If they determine that the leak is slow enough to safely allow a reentry attempt, I expect them to pack up the 3 cosmonauts who are assigned to that soyuz and send em home pronto while that window is open.

3. If this soyuz is now toast and the Russians have a spare somewhere on the ground, they will likely have to fill it with supplies and launch it, fast, unmanned to the station. We are in a dangerous, unprecedented time where there are astronauts on station with no ride home. Every emergency is now life-threatening until they can get another soyuz up there.

In an emergency there is one other option that they might consider; Dragon is human rated in theory for up to 7 people. That's what the original design was for. However, NASA only fits theirs out for 4 astronauts. Presumably, they could, in an emergency be used to carry the 3 soyuz refugees. Perhaps they would need to bring extra life support equipment and dump cargo to lose some weight. But it could be made to work. At a stretch, an unmanned cargo-dragon could even be used if appropriate life-support equipment could be employed. Such as putting the passengers in an EVA suit for the ride home.

Either way, it's thinking-cap time for the people at NASA and Roscosmos. Good luck!

[anotherQuarter]

To add to this it’s not only cosmonauts assigned to this soyuz it’s 2 Russians and 1 American. Doesn’t change making the right decision for protecting crew but may add complexity if Roscosmos is confident in the Soyuz for returning crew but NASA isn’t.

Additionally depending on damage Soyuz may be on a clock to leave no matter what (with or without crew) to prevent it from being stuck to ISS.

Big question is what caused the damage and thus what risk there is to re-entry. Lots of tough risk trades to make.

[rrmm]

Roscosmos & NASA disagreeing with each other on the integrity of the Soyuz would be very on brand for everyone.

Root cause and the next steps are going to be very interesting.

Luckily it seems everyone is safe for the time being.

[remarkEon]

This might be a myth but when I was a kid I assumed (or was told?) that there was always another space shuttle ready to go if there was a problem with the one in flight. Since SpaceX has nearly perfected quick turn launches, I have to believe that they can get one fueled up relatively quickly.

[cesarb]

> This might be a myth but when I was a kid I assumed (or was told?) that there was always another space shuttle ready to go if there was a problem with the one in flight.

I believe it was a myth. IIRC, one of the unusual things about the final Hubble servicing mission was said to be the sight of two space shuttles ready to go at the same time (one for the mission and a second one to be used as a rescue ship if necessary), implying that this wasn't done often (if at all) previously.

[rrmm]

Post Columbia accident, most of the shuttle missions were focused on the ISS where the crew could have taken refuge had there been a problem during ascent which prevented safe re-entry.[1]

As you note the Hubble mission (STS-125 with Atlantis) wouldn't have that option available due to its orbit, so NASA had the shuttle Endeavour ready to fly as STS-400 as a contingency.

[1] The plan would have been that crew stranded on the ISS would be picked up by a later shuttle, so NASA was obviously comfortable with the contingency of leaving a crew without transport off for a period of time during an emergency. These were designated STS-3xx missions and would have launched within 40 days of call up. The ISS could have supported the additional crew for 80 days.

[bryananderson]

This only became true after the loss of the shuttle Columbia on the STS-107 mission in 2003. After Columbia, a rigorous process was put in place for checking the heat tiles on the underside of the orbiter for damage. If damage was discovered, the shuttle crew would shelter aboard the International Space Station for about 40 days until a rescue shuttle came to get them. This mission profile was known as Launch On Need or Contingency Shuttle Crew Support. The rescue missions were numbered in the STS-3xx range. [0]

A different rescue mission profile was needed for STS-125, which serviced the Hubble Space Telescope and couldn’t reach the orbital inclination of the ISS. This rescue mission, STS-400, had to be ready to launch within three days of a problem being found.

The last planned shuttle mission was STS-134, with STS-335 as the LON mission. Since the hardware for 335 existed, NASA decided to fly it as an operational mission, STS-135. At this point there could be no backup shuttle, so 135 was flown with just four crew members who would shelter on ISS and come down one at a time via Soyuz over the course of about a year if the shuttle couldn’t re-enter.

What about the damaged orbiter stuck at ISS? Orbiters were quite expensive, so NASA developed hardware (which was stored on ISS) to attempt a landing of the empty orbiter via remote control. Whatever the probability of success, it was better than zero.

After the loss of STS-107, the investigation board asked NASA to devise a rescue that could have been attempted if the damage had been identified early in the mission. [1] The result was an audacious rescue plan that would have pushed two orbiters, their crews, and NASA itself to the absolute limit. We will never know if it could have been done.

[0] https://en.m.wikipedia.org/wiki/STS-3xx [1] https://arstechnica.com/science/2016/02/the-audacious-rescue...

[ShakataGaNai]

It's clearly a danger if a return vehicle becomes disabled for any reason. But I would be shocked in NASA and Roscosmos don't have contingency plans for exactly the situation described. They have contingencies for ...everything.

[cesarb]

> 2. If they determine that the leak is slow enough to safely allow a reentry attempt, I expect them to pack up the 3 cosmonauts who are assigned to that soyuz and send em home pronto while that window is open.

To make it worse... If I understood the situation in these twitter posts correctly, they were in the middle of a spacewalk. So they'd need to first quickly terminate that spacewalk, which also takes some time.

Edit: according to https://blogs.nasa.gov/spacestation/2022/12/14/spacewalk-can... they were still preparing for the spacewalk, so they weren't outside yet.

[rrmm]

I could see them making a contingency for stuffing everyone on dragon as an absolute last resort and moving some launches around to get a vehicle there asap. In anycase it'll give NASA an occasion to review their planning for these sorts of situations.

I'll be interested to see if they make any changes to station procedures or the vehicle complement they choose to keep on orbit.

[pifm_guy]

I assume that, while dragon was designed originally for 7, since the design has been changed to 4 people that other things have been adjusted that mean 7 is no longer an option. For example, the parachutes might be slightly smaller for the reduced expected weight. Or the environmental system can only deal with the heat, moisture and co2 of 4 astronauts not 7.

[rrmm]

Yeah, I imagine the conversation as more of a "could we make this work if we had no other choice" sort of thing. I don't imagine it would be considered under anything other than a dire emergency.

I don't think NASA would have a problem having fewer seats available for egress than crew for a short time as long as they were moving to rectify it.

[pacificmint]

One more option, if Russia couldn’t get an extra Soyuz up there in time to pick them up, would be to send an extra Dragon up empty to pick up the extras.

[rob74]

Empty except for some fitting space suits I assume?

[wmf]

Worst case you can ride Dragon without a suit. It's less safe but it's probably still safer than the shuttle.

[gpm]

Do they even need life support for the short descent to earth? I know they've brought mice up on cargo dragons, so the cabin's at a reasonable temperature. The only other obvious concern is oxygen levels...

[foobarbecue]

Don't they need the correct number of chairs? Maybe they're called "deceleration couches" or whatever? Seems like pretty significant chance of injury without that ...

[JanSolo]

In astronaut Mike Mullanes book, he mentions that they often used to fly shuttle re-entries outside of their seats. I'm sure a shuttle has a much softer entry profile than a capsule, but if it's possible, I'm sure they'd consider it in an emergency.

[foxyv]

Maybe they would do like we used to when I was a kid and double up a seat belt? It would suck, but I don't think it would kill anyone. Maybe...

[TrevorJ]

SpaceX presumably has more than a single Crew Dragon sitting around, wonder how quickly they could deliver those to ISS.

[rkagerer]

Wait - are you saying there is no built-in redundancy for one Soyuz going out of service?

[Toutouxc]

The redundancy is already there — both the ISS itself and the Soyuz parked there are able to keep the crew alive. If one of these fails, the other one will prevent immediate loss of life, but something still needs to be done ASAP about the situation.

[VLM]

2 is 1 and 1 is none.

Its like losing one drive in a RAID mirror; you still have a "RAID", well, kind of, but should be nervous until its replaced...

[pclmulqdq]

A "7-person" capsule only actually fitting 4 sounds like about the right discount rate for a Musk company.