Russian Nauka module plays leak-a-boo with International Space Station

Faulty backup radiator is bleeding coolant into the black

The International Space Station just sprung another leak. And you can give yourself a pat on the back if your first guess at the source was the Russian Nauka module.

The leak appears to be coolant from a backup radiator on Nauka.

Flight controllers spotted flakes from one of the Nauka radiators thanks to cameras on the orbiting laboratory. The crew was then asked to take a look, and NASA astronaut Jasmin Moghbeli confirmed them from the windows of the Cupola module. The window shutters on the US segment were closed as a precaution.

The crew is in no danger, although there is a risk that the windows could be contaminated, hence closing the shutters. The problem is how to deal with the issue and restore redundancy. While the primary radiator continues to work well, losing the backup is not ideal.

According to the Russian space agency Roscosmos, the leak is indeed coming from Nauka's backup radiator, which is mounted outside the module. One of the last Space Shuttle missions delivered the radiator in 2010 and left it on the Rassvet module. It was transferred to Nauka during a Roscosmos spacewalk in April.

Another Roscosmos spacewalk – also to relocate a radiator – in December 2022 had to be abruptly canceled after a coolant leak was observed from a docked Russian Soyuz vehicle. That leak resulted in an extended stay on the ISS for the crew while they waited for a replacement vehicle. An uncrewed Progress cargo spacecraft also experienced a coolant leak in February 2023.

Russian officials previously blamed micrometeoroid or orbital debris impacts for their leaky spacecraft rather than design or manufacturing flaws, and it will be interesting to see what the excuse is this time around. The space dog bit my pipework?

The Nauka Multipurpose Laboratory Module (MLM) has had more than its fair share of issues during its orbital lifetime. As well as being extraordinarily delayed, the module took the ISS on quite the wild ride thanks to some unexpected thruster firing after it arrived in 2021.

NASA has a pair of spacewalks coming up in October, with the first – involving ESA astronaut Andreas Mogensen – due this week. It is unclear if either will go ahead as planned. ®

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