Russian Nauka Module on ISS is Leaking

Back in July of '21, the Russian space agency Roscosmos launched a module called the Nauka (translates as "science") Multipurpose Laboratory Module (MLM) to the International Space Station (ISS) to replace their previous module, the Pirs (Pier) module, which had been part of the ISS for 20 years.  Yesterday, at around 1PM Eastern (1700 UTC) personnel in the ISS mission control in Houston spotted toxic ammonia flakes, looking like snow flurries, on video downlinks.  A few hours later, acting on a report from Mission Control, NASA astronaut Jasmin Moghbeli looked out of the large windows on the ISS and saw that it was snowing in space.

This is the third time in 10 months that Russian hardware docked to the ISS has started leaking from its cooling system. 

On December 14, 2022, as two cosmonauts were preparing to conduct a spacewalk outside the space station, the Soyuz MS-22 spacecraft docked nearby began to leak uncontrollably from its external cooling loop.

The MS-22 Soyuz was the spacecraft that American Astronaut Frank Rubio and his two Russian shipmates were supposed to ride back to Earth in March and instead returned two weeks ago; explained in more detail in the first story here.  

Additionally, on February 11, 2023, the Progress MS-21 supply ship attached to the International Space Station lost pressure in its external cooling system. Once again, all of the coolant on board a Russian spacecraft leaked into space due to a rupture.

In both cases, Russian officials blamed both coolant system leaks on "an external impact," pointing toward a micrometeorite or small fragment of orbital debris as the cause.  Considering the size of the ISS and all the hardware that is and has been attached to it and that hasn't been hit by some sort of debris like that, the claim kind of causes a raised eyebrow.  It simply can't be ruled out as an odd coincidence.  Still, some NASA officials privately questioned whether both of these leaks really were caused by impacts in space rather than other technical defects in the hardware; there just wasn't any hard data to back that.   

Russia's Nauka module as seen from the ISS. I think this is a photo on file and those white puffy things are clouds well below the ISS, not ammonia "snowflakes."  Image credit: Roscosmos. 

The leak has been traced to an older radiator, launched on Space Shuttle mission STS-132 in 2010.  It was originally intended for use on another Russian module, called Rassvet.  A Roscosmos spacewalk in April 2023 transferred the then-functional backup radiator to Nauka.  

As of now, NASA has said the ISS crew was never in any danger from the leak, saying the leak has "no impacts to the crew or to space station operations," and that the primary radiator for Nauka continues to work normally.