A damaged Soyuz may leave the crew without delivering it home

Although strangely beautiful in its own way, it is a sight no astronaut would like to see: their spacecraft, the only way they have to return to Earth, eject countless iridescent droplets from Something in the space.

When the crew Apollo 13 Seeing their crafts bleed during their trip to the Moon, it was clear that the mission, and ultimately their lives, were in real danger. Fortunately, the current situation is not nearly as dire, as the leaky Soyuz MS-22 spacecraft docked at the International Space Station poses no immediate danger to those aboard the orbiting laboratory. But it’s still an unprecedented case, and bringing its crew home will require engineers on the ground to make some very difficult decisions.

This situation is still evolving, and neither NASA nor its Russian counterpart Roscosmos has released many details. But we can make some educated guesses from the video and photos we’ve seen of the stricken Soyuz capsule, and from what’s been shown to the public so far, things don’t look good.

Fuel free

On Wednesday the 14th, as Russian cosmonauts Sergey Prokopyev and Dmitry Petlin prepared to begin a scheduled extravehicular activity (EVA) that would have whisked them off the station, an alert went off indicating coolant levels in the docked Soyuz MS-22. capsule was going down. When external cameras were moved to the spacecraft, it was immediately clear that this was not a false alarm – liquid was seen pouring out from the rear of the vehicle.

As shown in the diagram above, the Soyuz pumps coolant through a pair of heat exchangers located in the orbital module (left) and descent module (center), which eventually makes its way to several external radiators mounted outside the service module (right). The coolant lines connecting these units actually run the length of the vehicle’s exterior, although they are obscured from view by the thermal blankets that cover most of the vehicle’s exterior.

While the exact cause of the leak is not yet known, the current theory is that a small meteorite or other small piece of space debris hit either the radiators or one of the external cooling lines. The hope was that a closer examination over the weekend might help determine the cause of the leak, but in any case, the result is the same. With no way to stop the flow, it is believed that all of the system’s coolant was dumped into the sea during the event, leaving the system inoperable.

The system is responsible not only for keeping the interior of the descent module at a comfortable temperature for its human occupants, but also for cooling the plane’s computers and other equipment buried deep in the craft. Trying to repair and refill the cooling system while in orbit would be very difficult, and it would certainly be considered too risky to even attempt. So the question Russian engineers must now answer is whether the Soyuz can safely return its crew of three to Earth with its cooling system offline.

remote rescue

At the time of writing, no official announcement has been made, but many space experts argue that the safer approach is to assume Soyuz MS-22 is no longer airworthy. While testing of the system performed after the leak was discovered showed that the vehicle appeared to operate normally, and that its thrusters were still working, the possibility that the computer would overheat and shut down during flight presented an unacceptable risk to the crew. Re-entry can be performed manually if necessary, but the capsule is likely to land outside the specified coordinates, complicating retrieval operations.

Salyut 6 with Soyuz and Progress spacecraft docked.

Of course, this assumes the cooling system is the only thing damaged. If the rover hits a piece of space debris, there’s no telling what other systems it could have collided with without a thorough check–something an EVA could be harder to do.

If Roscosmos decides that Soyuz MS-22 is no longer fit for purpose, they will likely decide to teleport the next Soyuz to the International Space Station so that it can replace the damaged vehicle. If at all possible, they may push the launch date currently scheduled for March 2023.

While such a situation is extremely rare, it is not without precedent. In April 1979, when the viability of the Soyuz capsule came into question, the crew of the Soviet Salyut 6 station had to wait on board a new spacecraft to bring them home. In the end, both craft made it back to Earth safely, but that doesn’t mean it wasn’t worth the extra time and expense to make sure the crew had the best chance of survival.

Not enough lifeboats

But there is a problem with this plan. If it is determined that the Soyuz MS-22 is no longer safe for its occupants and needs to be replaced, this means that for the first time in its history, there will not be enough spacecraft docked at the International Space Station to bring all of the crew home in the event of an emergency.

Should the International Space Station suffer some catastrophic failure before a new Soyuz is dispatched, Sergey Prokopyev and Dmitry Petlin, as well as American astronaut Francisco Rubio, would have no safe way out of the station. As a matter of necessity, they would likely be directed to board a semi-functional Soyuz MS-22 and prepare to dismount if they needed to evacuate, but what happens next in this nightmare scenario is anyone’s guess. We hope we don’t have to find out.

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