here’s what we know

A Russian spacewalk was canceled at the last minute on December 14 following the discovery of a leak on the Soyuz spacecraft, which is docked to the International Space Station (ISS). What exactly do we know about the incident?

Ammonia leaks into the room

Cosmonauts Sergey Prokopyev and Dmitry Petelin, dressed in their suits, were about to go into space when flight controllers told them to stop operations due to a leak on the spacecraft Soyuz MS-22. It appeared to be coming from an external cooling loop located on the back of the capsule. NASA’s live images then revealed countless ammonia particles escaping into space.

At no time were the ISS crew members in danger. But this leak, which represents one of the most serious incidents of the orbiting laboratory’s history, raises questions about the viability of the Soyuz spacecraft. The latter will bring the cosmonauts Sergey Prokopyev, Dimitri Petelin and the American Frank Rubio back to Earth next spring.

Russia was never able to close the leak. It only finally stopped when the coolant reserves were used up, on 15 December.

Immediately after, Russian air traffic controllers attempted to use the European robotic arm attached to the Russian segment of the station to observe the rear end of the Soyuz. The maneuver yielded no conclusive data.

Ammonia particles dumped into space from the Soyuz. Credit: NASA TV

More inspections

The Soyuz is a robust spacecraft. A priori, therefore, this incident should not prevent him from disconnecting from the space station and returning to Earth, but will he be able to do so in complete safety?

If engineers determine there is a problem, a Replacement Soyuz will have to moor at the station. These vehicles have the ability to start and hook themselves. However, that would mean that the three crew members would not have no emergency evacuation vehicle until the replacement ship arrives.

In addition, if the other four astronauts on board flew on a SpaceX Crew Dragon capsule in October, this vehicle cannot hold seven people to return to Earth.

NASA used its Canadarm2 robotic arm to 17.6 meters long to get a closer look at the Soyuz spacecraft this weekend. This visual inspection revealed a gap of approx. 0.8 mm in diameter. The cooling system therefore appears to have been affected micrometeoroid debris.

Meanwhile, Roscosmos also tested the spacecraft’s thrusters early Friday morning to determine if there were problems with its propulsion system. This test was nominal according to the sources.

Possible overheating of avionics

Since the external cooling circuit of the Soyuz MS-22 spacecraft is now useless, the main current concern is overheating of flight computers (flight electronics). Since these computers are integrated quite deep into the craft, it is difficult to cool them with the station’s ambient atmosphere by leaving the hatch open. However, they are of great importance to ensure precise entry of the capsule to its landing site.

Additionally, the ISS is currently in “high beta,” meaning it is constantly illuminated by the Sun. Over time, this can cause the flight computers to overheat. Without them, the procedure can still be done manually, but the maneuver is much more risky.

For this reason, the Russian authorities are considering an early departure of the Soyuz MS-22 crew as early as this month. So far, no final decision has been made.

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