Damaged Soyuz could leave crew with no way home

Though oddly beautiful in its own way, it’s a sight no astronaut wants to see: their spacecraft, the only way for them to return to Earth, ejecting countless iridescent droplets of Something in the space.

When the crew of Apollo 13 saw their ship literally bleed on their journey to the Moon, it was clear that the mission, and ultimately their lives, were in danger. Fortunately, the current situation is not so dire, because leak of the Soyuz MS-22 spacecraft docked at the International Space Station poses no immediate danger to those aboard the orbiting laboratory. But this is still an unprecedented situation, and to bring its crew home, engineers on the ground will have to make some very difficult decisions.

This situation continues to develop, and neither NASA nor its Russian counterpart Roscosmos has released many details. But we can make educated guesses from the video and images we’ve seen of the damaged Soyuz capsule, and from what has been shown to the public so far, things are not looking good.

Runs empty

On Wednesday the 14th, as Russian cosmonauts Sergey Prokopyev and Dmitriy Petelin were preparing to begin a scheduled extravehicular activity (EVA) that would have taken them outside the Station, an alert went off indicating that the fluid levels of cooling in the docked Soyuz MS-22 capsule were falling. When panning the external cameras towards the spacecraft, it was immediately clear that this was not a false alarm – as liquid could be seen spewing 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 the descent module (center), which eventually goes to several external radiators mounted outside the service module (right). The coolant lines that connect these modules actually run the length of the exterior of the craft’s hull, though they’re hidden by the thermal blankets that cover most of the vehicle’s exterior.

Although the exact cause of the leak is not yet known, the current theory is that a micrometeoroid or other small space junk hit the radiators or one of the external cooling ducts. The hope was that further examination over the weekend might help determine the cause of the leak, but either way the result is the same. With no way to stem the flow, it is believed that all of the coolant in the system was spilled overboard during the event, leaving the system unusable.

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

Remote Rescue

At the time of this writing, no official announcement has been made, but many space experts believe that the safest approach is to assume that Soyuz MS-22 is no longer in state of flying. While a system test performed after the leak was discovered showed that the vehicle appeared to be operating normally and its thrusters were still functional, the possibility of the computer overheating and shutting down during flight poses an unacceptable risk to the aircraft. ‘crew. The re-entry procedure can be performed manually if absolutely necessary, but it is likely that the capsule would land outside the designated coordinates, complicating recovery operations.

Salyut 6 with Soyuz and Progress spacecraft docked
Salyut 6 with Soyuz and Progress spacecraft docked.

Of course, that’s assuming the cooling system is the only thing damaged. If the craft was hit by a piece of space junk, it’s unclear what other systems might have been hit without a thorough examination – something that could difficult to do from an EVA.

If Roscosmos determines that the Soyuz MS-22 is no longer suitable, it will likely decide to fly the next Soyuz to the ISS remotely so that it can replace the damaged vehicle. If possible, they could even push back the currently scheduled launch date to March 2023.

Although extremely rare, such a situation is not without precedent. In April 1979, when the viability of their Soyuz capsule was called into question, the crew of the Soviet station Salyut 6 had to wait for a new spaceship to bring them home. In the end, both vehicles made it back to Earth safely, but that doesn’t mean it wasn’t worth the extra time and expense to ensure 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 human occupants and needs to be replaced, it will mean that for the first time in its history, there will not be enough spacecraft docked at the Station. International Space Agency to bring all of the crew members back in case of emergency.

In the unlikely event that the ISS suffers a catastrophic failure before a new Soyuz can be sent, Sergey Prokopyev and Dmitry Petelin, as well as American astronaut Francisco Rubio, will have no safe way to leave the Station. Out of necessity, they would likely be tasked with boarding the semi-functional Soyuz MS-22 and preparing to undock if they needed to evacuate, but what happens after that in this nightmarish scenario is anyone’s guess. Hopefully we won’t have to find out.

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