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Strike From a Space Rock May Have Caused Soyuz Coolant Leak at the ISS

NASA and Roscosmos are investigating yesterday's troublesome spacecraft leak, which could affect the astronauts' ride back to Earth.

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A livestream on NASA TV showed the leak outside the ISS.
A livestream on NASA TV showed the leak outside the ISS.
Screenshot: NASA

Ground teams are investigating the cause of an upsetting coolant leak that erupted yesterday on the Russian Soyuz Ms-22 spacecraft docked to the International Space Station (ISS). Experts are now saying that a micrometeorite may have been responsible.

Micrometeorites are tiny pebbles, roughly the size of a grain of sand, that zip around space at high speeds, occasionally impacting spacecraft. The Webb Telescope’s primary mirror was smacked by a micrometeorite earlier in May, slightly impacting its performance. They may be small, and usually cause no harm, but should a micrometeorite manage to hit something like a spacecraft radiator, well, that has the potential to produce some badness.


Sergei Krikalev, a former cosmonaut who heads the crewed space flight program for Roscosmos, was quoted in Russian state media outlet TASS as saying that the cause of the leak “may be a micrometeorite entering the radiator.” A possible consequence of a collision could be “changes in the temperature regime,” he added. “No other changes in the telemetric parameters of either the Soyuz spacecraft or the [ISS] on the Russian or American segments have been detected,” he said.

That a micrometeorite struck the Soyuz radiator is a distinct possibility. But it’s also possible that a tiny piece of human-produced space junk is responsible for the leak. According to the European Space Agency, there are currently around 130 million pieces of space junk in Earth orbit that measure between 1 millimeter and 1 centimeter in size.


On Wednesday, ground teams discovered a fountain of particles pouring out from the docked Soyuz spacecraft. The unusual sight, which lasted for hours, was traced to a coolant leak likely coming from the external radiator cooling loop of the Soyuz spacecraft, NASA wrote in a blogpost on Thursday.

The leak was first detected around 7:45 p.m. ET on December 14 when “data from multiple pressure sensors in the cooling loop showed low readings,” the space agency added.

Two Russian cosmonauts were preparing to exit the space station for a routine spacewalk, which has now been postponed indefinitely due to the leak. Thankfully, the crew on board the ISS were not harmed, but it’s not yet confirmed whether the Soyuz spacecraft suffered meaningful damage. The spacecraft carried NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin to the ISS in September, and is set to take them home when their expedition ends in the spring of next year.

“Roscosmos is closely monitoring Soyuz spacecraft temperatures, which remain within acceptable limits,” NASA wrote in its blog. “NASA and Roscosmos continue to coordinate external imagery and inspection plans to aid in evaluating the external leak location.”


The space agencies will also be using Canadarm2, a robotic arm installed on the outside of the ISS, to get a closer look at the Soyuz spacecraft. Canadarm2 was struck by a flying piece of space junk, or possibly a micrometeorite, in June 2021, which created a hole on the robotic arm.

If ground teams deem the Soyuz spacecraft unusable for a crewed trip back to Earth, then the three astronauts on board the ISS may need to wait for another spacecraft to make its way to low Earth orbit and transport them back home.


We’ll be following the story as it develops and providing updates on the leaky spacecraft.

More: Space Junk Has Blasted a Hole in a Key Space Station Tool