Why the International Space Station keeps leaking
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The Earth seen from the International Space Station on April 3, 2026. Photo: NASA/Chris Williams
NASA's decision to order International Space Station astronauts to prep for a hasty departure Friday was the latest — and most dramatic — episode in a years-long saga tied to mysterious leaks in a Russian module.
Why it matters: The ISS is nearing the end of its expected lifespan, but it's still invaluable for America's crewed spaceflight and scientific ambitions.
Driving the news: NASA on Friday ordered five astronauts to assume the "safe haven" configuration: Board the SpaceX Crew Dragon spacecraft currently docked with the ISS, and prepare for an emergency departure.
- NASA later said that order came after Russian space agency Roscosmos decided to investigate — and hopefully fix — persistent leaks plaguing its Zvezda service module.
- The astronauts didn't actually evacuate.
Roscosmos later paused "and did not perform the structural repair work," NASA said in a statement.
- The Russian agency instead conducted "additional measurements and data assessments, which included inspection of suspected areas of interest and review of areas where sealant was previously applied."
- "NASA strongly supported that decision, and as a result, following that decision, [the astronauts] ended their safe haven activities and returned to normal operations aboard the orbiting laboratory."'
Zoom out: The ISS has experienced several leaking problems over its nearly three-decade lifespan.
- The latest, involving Russia's Zvezda module, has been an on-and-off issue since Sept. 2019.
Zoom in: "Engineers believe the leaks are caused by microscopic cracks in the module's structure," Ars Technica reports.
- "Russian cosmonauts have repeatedly inspected and attempted to seal the cracks, but a permanent fix has eluded them."
Threat level: Roscosmos says there's "no threat to crew safety or onboard systems" — but any leak on a laboratory flying 250 miles above the Earth's surface at speeds of 17,500 miles per hour obviously presents a concern.
- Astrophysicist Jonathan McDowell tells Scientific American: "The worry is that a small crack could suddenly get catastrophically bigger."
- "That's unlikely but not impossible, and that would risk loss of the station and crew."
Between the lines: Friday's episode underscores the complex relationship between NASA and Roscosmos.
- The two major ISS partners represent nations that once competed against one another in the Space Race.
- They now have shaky relations at best in matters both terrestrial and celestial, and don't always agree on actions affecting the station as a whole.
What's next: The ISS is set to be de-orbited in 2031, with a fiery death in Earth's atmosphere offering a dramatic end to over three decades of unprecedented international cooperation in space.
