The most serious emergency in many years has happened on the International Space Station – and this directly affects the astronauts on it. What exactly happened, what danger threatens the Soyuz MS-22 spacecraft and why the only salvation may be an urgent evacuation of the crew?On December 15, Roscosmos cosmonauts Sergei Prokopyev and Dmitry Petelin were supposed to go overboard the International Space Station to transfer the ERA manipulator radiator from the Rassvet module and install it on the Nauka module.
However, during the preparation, when the astronauts were preparing to switch their Orlan spacesuits to internal power inside the Search module (MIM2), an emergency situation occurred with the Soyuz MS-22 manned spacecraft docked to the station.
This situation is clearly illustrated by the fountain of splashing particles captured on video by the station's cameras. In front of us is an outgoing coolant from the depressurized circuit of the ship's thermal control system. What is it?
What happened? The main problem for spacecraft in space is cooling.
The plate radiators familiar on earth are ineffective in vacuum conditions, so you have to increase their size and do liquid cooling.
In other words, the video cameras recorded a leak of the punctured cooling system. Something punctured. Simultaneously with the leak, the ship's diagnostic system alarm went off, indicating a drop in pressure in the cooling system.
There are two interconnected cooling circuits on the Soyuz spacecraft. Firstly, this is the internal contour of residential compartments (FGM) for heat collection in residential modules (household compartment and descent vehicle) and from the instruments. Secondly, the external contour of mounted radiators (PRC), which serves to remove excess heat from appliances and living compartments. Excess heat is discharged through the coils of the PRC on the body of the Soyuz unit compartment.
Air cooling in the hermetic compartments and heat collection occurs due to the operation of the so-called cooling and drying unit, through which the circulating coolant passes in the main. Further, the heated coolant in the FGM contacts through a liquid-liquid heat exchanger with the PRC circuit, as a result of which the collected heat is transferred. The PRC heats the docking unit, the engines, and only then dumps the remaining heat into space through the surface of the coil by radiation.
The liquid temperature of the internal circuit is regulated by automation and liquid flow regulators. When it gets too hot for astronauts, the flow rate increases, the heat discharge becomes more intense, the temperature in the cabin decreases.
Judging by the video, the external cooling circuit (PRC) is damaged on the Soyuz MS-22. On the other hand, this is not so important, since both circuits are interconnected. If one is damaged, the efficiency of the second one is reduced to almost zero.
In addition to the two main circuits, there is an auxiliary one on the ship, which, after docking with the station, provides heat transfer from the station to the contour of the living compartments. However, it is difficult to say how effectively it will work in the current conditions.
Evacuation is possible What's next?
The lack of thermoregulation will gradually lead to the failure of the ship's systems and instruments. This cannot be allowed. This means that if the temperature of the ship increases, then there will be only one way out – the evacuation of the Soyuz MS-22 crew on their damaged ship.
Despite the damage received, this should not lead to complications during the descent.
The fact is that the Soyuz manned spacecraft consists of three parts: descent vehicle, household and instrument-aggregate compartments. The astronauts are in the descent vehicle – the only part that returns to Earth. Everything else, including the instrument-assembly compartment, burns in dense layers of the atmosphere.
The ship's engines are required to perform a departure maneuver from the station and a descent maneuver. During normal operation, all these operations will occur automatically, but if the situation becomes more complicated, the crew of the Soyuz MS-22 spacecraft will have to do the work. Naturally, the responsibility for making such a decision will be on the commander of the Soyuz MS-22 spacecraft Sergey Prokopyev.
The stumbling block What could have caused damage to the thermal control system?
There are no results of an official investigation yet, which means that only versions and assumptions can be voiced. The main version is the impact of a micrometeorite that broke through the cooling system. Additional – defective cooling system.
Micrometeorites or fragments of space debris occasionally collide with the International Space Station. There is a photo of a chipped porthole of the Dome module, obtained in 2016, photos of collision marks on the station body, damage to solar panels. Even the slightest splinter of paint or metal the size of a nail clipping becomes deadly in space due to huge speeds. The recently launched James Webb telescope collided with a micrometeorite just a few weeks later, albeit without any special consequences.
It may very well be that the Soyuz MS-22 was unlucky and it was a small fragment that found it. Yes, it would be amazing bad luck, but this option is very likely. Moreover, right now the Earth is passing through one of the most powerful meteor showers of the Geminids. The beautiful sight of "shooting stars" on Earth could cause serious problems in space.
As for hypothetical problems with the marriage of the cooling system – until today, Soyuz ships have not had such problems, and I would very much like to hope that they will not.
Problems and consequences The Mission Control Center, together with the astronauts, made every effort to determine the cause of the emergency situation.
Working in orbit, cosmonaut Anna Kikina, using the ERA robotic manipulator, took several pictures and video clips of the leak site from a minimum distance. They were transferred to Earth. Now specialists will have to determine exactly how the hole in the cooling system appeared, whether there is additional damage and what actions the crew will need to take.
Yes, this is a difficult situation. There has never been anything like this on the International Space Station. There are many decisions to be made, possibly very difficult ones. Depending on which of the cooling systems was damaged, it will become clear what to do with the liquid splashes that hit the walls of the station, portholes and instruments. The fact is that different systems have different types of coolant, too.
In the meantime, the station crew made sure that everything was sealed, there was no danger, and the Mission Control Center sent them to sleep. The guys really need a good rest. Tomorrow, they may have to solve many more problems.
Sometimes we forget that space is an extremely hostile environment for humans. It began to seem that the work of the International Space Station is no different from similar activities on Earth. Alas, this is not so – and space once again reminded of its danger. One mistake can cost human lives. I would like to hope that the astronauts, together with specialists on Earth, will find the best way out of this situation. We can only keep our fingers on them.
Mikhail Kotov
