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Cosmonauts seal air leak in Russian module of the International Space Station

The International Space Station, as seen in 2018.
(Image credit: NASA)

Two Russian cosmonauts will drill holes and apply sealant to stop two cracks in one of the oldest modules of the International Space Station.

The cracks are thought to be the source of a tiny air leak from the station that NASA and Russia's space agency Roscosmos have been investigating for several months. Officials with Roscosmos and NASA have repeatedly emphasized that the cracks are small and that the station's seven-person crew is in no danger. In a statement Thursday (March 4), Roscosmos noted one of the two cracks was only 0.86 inches (22 mm) long and about 100 microns wide — just slightly wider than a typical human hair. 

NASA's statement, also issued Thursday, focused on just one of the cracks — but said the crew is in no danger and "the space station has ample consumables aboard to manage and maintain the nominal environment." NASA also pointed out that this crack sealing effort is part of ongoing work this past year "to isolate and fix the source of a slight increase above the standard cabin air leak rate aboard the station."

The leak is in the service module of the Zvezda module, which launched to space in 2000 and forms part of the Russian region of the space station. Zvezda supports the station's life support systems (which have some backup in the U.S. orbital side of the station) and also contains living quarters for two cosmonauts.

Since the leak is on the Russian side, Expedition 64 cosmonauts Sergey Ryzhikov and Sergey Kud-Sverchkov are taking on the repair work, with consultation from ground support on Earth. They are using a 3 mm drill and applying two kinds of sealing paste and sealing material, Roscosmos said.

"The holes will be sealed straight away to minimize the pressure drop," Roscosmos added in the same statement. "After that, several more layers of seal paste will be applied with a reinforced patch, which will be covered with another layer of sealing paste. The metal borings will be sent back to Earth in addition to the instrument data and photos collected earlier for further analysis."

Cosmonauts patched up a leak in Zvezda in October 2020 following initial reports of a very small drop in air pressure, dating as far back as September 2019. This leak was so small that the partners deferred it given the small size of the crew and their high workload at the time.

Last week, Russian news provider Sputnik News reported that a commission of Russian space experts including those from Roscosmos said the cracks are due either to metal fatigue or a micrometeorite impact. Both of the new cracks should be patched up by Friday (March 12), Sputnik News added on March 6.

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Elizabeth Howell

Elizabeth Howell is a contributing writer for Space.com who is one of the few Canadian journalists to report regularly on space exploration. She is the author or co-author of several books on space exploration. Elizabeth holds a Ph.D. from the University of North Dakota in Space Studies, and an M.Sc. from the same department. She also holds a bachelor of journalism degree from Carleton University in Canada, where she began her space-writing career in 2004. Besides writing, Elizabeth teaches communications at the university and community college level, and for government training schools. To see her latest projects, follow Elizabeth on Twitter at @howellspace.