Scivillage.com Casual Discussion Science Forum

Continuing as I write this. Two Russian cosmonauts were suiting up for a spacewalk, when a significant coolant leak was detected in Soyuz MS-22, docked to the Russian side of the station. The spacewalk was called off and Russian controllers have been trying to figure out where the leak precisely is and what they can do about it.

Everyone on the Space Station is safe and in no danger. But if the Soyuz loses all the ammonia coolant in its life support system, it might be put out of action, and three cosmonauts (rwo Russians and an American) were scheduled to return to Earth in it.

The leak has been happening for two hours now, and the Russians seem unable to shut it off.

https://twitter.com/Space_Station/status...6187402240

Well, the Russians were never able to stop the leak in Soyuz MS-22's life support cooling loop. It finally stopped leaking, but only because all the ammonia coolant had been lost into space.

They are still assessing what impact this will have on the Soyuz's ability to return humans to Earth. If it turns out that the Soyuz is unsafe, Russia will have to send up a replacement Soyuz (if they have one available) or SpaceX will have to send up a Crew Dragon (if one is available).

But there already is a Crew Dragon at the Station. The Crew Dragons were originally designed to carry seven astronauts, but nasa didn't like that seating arrangement and went with four seats. But theoretically a Crew Dragon can still carry seven in an emergency I think, by putting three additional under the seats on some kind of padding.

I don't like the idea of bad karma. But the alternative of the Russians doing it deliberately draws a blank, as to what the [productive for them] motive would be. So coincidental misfortune it is. When it rains it pours, yata, yata...

The talk of broomsticks was a bit "Kama come and get me if you can." and apparently it can.

There's going to be a press briefing tomorrow at 11 AM EST (8 AM PST) to discuss the Soyuz coolant leak. They will broadcast the audio on nasa-live.

https://www.nasa.gov/live

The Station's Canadian Arm said "Hold my beer", put down its hockey stick and waved a camera around the Soyuz so that photos could be taken from all angles. Roscosmos has been examining them along with their own data. Apparently temperatures inside the Soyuz remain within acceptable limits. Tomorrow's briefing will discuss the future course of action.

https://www.nasa.gov/press-release/nasa-...leak-probe

Stuff from the briefing

Leak came from a single hole, that seems to have been caused by micrometeorite hit. Hole is only about 1 mm across, in a small crater less than 1 cm across.

Station crew first discovered the leak by seeing video of the plume. (They had video going in preparation for a Russian spacewalk that was being readied but was then canceled.) Crew alerted Mission Control Moscow which confirmed a pressure drop in the Soyuz coolant system.

They are still undecided whether they can fly crew on the damaged Soyuz. Right now it is being cooled by air from the Space Station module it is docked to, so fact temperature inside is still in acceptable limits is not an indication it will remain acceptable in flight.

They expect to reach a decision on the vehicle's status next week.

If they decide not to fly crew on it, they might still use it to perform an uncrewed reentry, to gather data on what internal conditions are with cooling system out of service.

The next Russian crew rotation is planned for March. They could move that launch up to February and send it uncrewed, if a replacement Soyuz is needed to return crew currently on the Station.

The docked Soyuz and Dragon vehicles serve as Station lifeboats ("safe-havens" they call them). So the Russian side is currently without its lifeboat.

Other than that, things are fine on the Space Station. The Americans are currently performing a spacewalk to install new solar panels sent up on the last Cargo Dragon. (They are flexible and are sent rolled up.)

Different, and if true more serious, Soyuz Trouble is being reported. This problem could potentially kill Russia's Soyuz human spaceflight program for months to come.

It seems that Kazakhstan has seized the Russian space-launch facility at Baikonur. The reason is reported to be Russian failure to pay 2 billion rubles ($26 million US) in back rent for its use. Since this is currently the only site that launches crewed Soyuz rockets, that creates big problems for crew rotations to the ISS.

https://twitter.com/revishvilig/status/1...8344972288

Russia has two other launch sites that launch Soyuz rockets. One is Plesetsk in the subarctic taiga some 500 miles north of Moscow. This site seems to specialize in military launches and puts up lots of spy satellites into polar orbits. The other cosmodrome is Vostochny in the Russian far east near the Chinese border. This one is intended to become Russia's primary launch site and human spaceflights are planned from here in the future. It's unclear how quickly they could bring human spaceflights at Vostochny forward if they had to.

My guess is that the Russians will work things out with the Kazakhs. After all, the Kazakhs would have little use for Baikonur without Russian rockets to launch from there, and it represents a bit of prestige and a money-maker for them (provided they can make Russia pay the agreed-upon rent).

The Soyuz with the bad cooling system has left the Space Station for its return to Earth, filled with cargo instead of cosmonauts. I expect the Russian engineers want to learn what temperatures inside are like during reentry without the air conditioner.

Russia has already sent up another empty Soyuz to serve as a replacement ride for the cosmonauts who were scheduled to return to Earth in this one.

Roscosmos photo

More very serious Soyuz Trouble!

It happened yesterday after Soyuz MS-28 successfully launched from Site 31 at Baikonur Cosmodrome, carrying three cosmonauts to the Space Station (one of them an American).

A big part of the Site 31 collapsed. It seems that there's a big part of the launch pad that the Russians call the "maintenance cabin". This is a sliding platform that goes under the rocket so that technicians can access the first stage engines when the rocket is on the pad. (Now sadly lamented Pad 1 at Starbase had a similar but smaller and more mobile platform that everyone called "the dance floor".) When time comes for launch, these platforms move away to get out of the rocket blast. (The new Pad 2 being completed at Starbase eliminates the 'dance floor' since the goal is that the Raptor 3 engines won't need any servicing on the pad. If they do, the booster will have to be lifted off the pad by the Arms and placed on a work stand next to the pad.)

And after yesterday's Soyuz launch, the Baikonur maintenance cabin collapsed. It probably shouldn't be surprising since Site 31 has been there since 1965 in the old Soviet Union days. The Russians don't have the money to replace it (though they have upgraded it) and their attitude is 'If it ain't broke, don't fix it'.

Well, it's finally broke. And that's serious, since this is Russia's only pad for crewed space launches (even though it isn't in Russia, it's in Kazakhstan). All Russian crew and cargo flights to the Space Station will have to be halted until this is dealt with, which could take at least six months given the size of the task. Luckily Russia has several more of these maintenance cabins at Plesetsk and at Vostochny. But they are needed for Soyuz booster satellite launches there, and moving and installing them at Baikonur (they are ~20 tons big) would be a huge job.

Katya Pavlushchenko (who has extraordinarily good connections within the Russian space program) says she spoke with the Russian engineers. They can only speculate since an accident inquiry has only just begun, but to them it looks like the maintenance cabin ran off its rails into the flame trench. It weighs ~20 metric tons and moves out of the way of the rocket blast on rails. But the rocket blast exerts lots of force that can displace it, so it is supposed to lock into place to keep it from moving. Initial appearances suggest that the locks weren't properly set or else they failed.

Photos by Katya Pavlushchenko

Inside the maintenance cabin before the collapse.



After the collapse, showing the maintenance cabin upside down in the flame trench

Eric Berger is on the case

https://arstechnica.com/space/2025/11/ru...e-station/

"In a terse statement issued Thursday night on the social media site Telegram, the Russian space corporation that operates Soyuz appeared to downplay the incident...

However video imagery of the launch site after liftoff showed substantial damage, with a large service platform appearing to have fallen into the flame trench below the launch table. According to one source, this is a platform located beneath the rocket, where workers can access the vehicle before liftoff. It has a mass of about 20 metric tons and was apparently not secured prior to launch, and the thrust of the vehicle ejected it into the flame trench. “There is significant damage to the pad,” said this source...

...Russia has plenty of launch pads, both in Russia and neighboring countries, including Kazakhstan, that were formerly part of the Soviet Union. However, Site 31 at Baikonur is the country’s only pad presently configured to handle launches of the Soyuz rocket and two spacecraft critical to the space station, the cargo-only Progress vehicle and the Soyuz crew capsule...

...Anatoly Zak, of Russian Space Web, noted that there are other Soyuz pads elsewhere in Russia, but none are readily configurable to handle Progress and Soyuz spacecraft missions.

Roscosmos, in its statement, said the issue would be taken care of. “All necessary spare components are available for repair, and the damage will be repaired shortly.”

...so far NASA has not commented on the implications of damage to Site 31 in Kazakhstan. However one source familiar with the agency’s relationship with Russia said there are multiple concerns...

...Not only does this cargo vehicle bring supplies to the Russian segment of the station, it is used as a primary means to reboost the space station’s altitude. It also services the Russian thruster attitude control system which works alongside the US control moment gyroscopes to maintain the station’s attitude and orientation...

...the US cargo supply ships, SpaceX’s Dragon and Northrop Grumman’s Cygnus, have also demonstrated the capability to reboost the space station. But long-term it is not immediately clear whether US vehicles could completely make up for the loss of Progress vehicles..."