NASA directs ISS crew to board spacecraft amid leak fix attempt

Five astronauts were forced to seek shelter aboard a spacecraft attached to the International Space Station Friday as their crewmates worked to address an air leak in the Russia-controlled side of the orbiting laboratory.

In a statement Friday evening, NASA indicated that its counterparts at Russia’s space agency, Roscosmos, had devised a plan to cut a bracket “to better access an area identified as a possible leak source for further inspection.”

The US space agency said the approach “could have resulted in elevated risk to the structure in the area.” That’s why NASA ordered the astronauts to take shelter and be prepared for an emergency evacuation.

The astronauts who boarded the spacecraft included all four crew members of the SpaceX Crew-12 mission who flew to the orbiting laboratory aboard the Dragon spacecraft: NASA’s Jessica Meir and Jack Hathaway, Sophie Adenot of the European Space Agency, and Roscosmos cosmonaut Andrey Fedyaev. NASA’s Chris Williams, who arrived at the ISS aboard a Russian Soyuz spacecraft, also sheltered with the Crew-12 astronauts.

But Roscosmos’ effort to cut a bracket to address the leak did not ultimately move forward.

NASA lifted its order for astronauts to seek shelter shortly after it was implemented as the Russian space agency “paused Friday’s structural repair efforts … as more measurements and data is assessed.”

The US space agency added in its Friday statement that it “strongly supported” Roscosmos’ change of plans.

Cracks and leaks located in a portion of the space station operated by Russia — within a transfer tunnel between a module called Zvezda and a docking hatch — have been a known concern as far back as 2019. The latest ordeal began when Roscosmos took new measurements of the module’s air pressure around the arrival of a cargo spacecraft in April, according to NASA.

It’s not yet clear when repair efforts will resume.

Cosmonauts discovered two potential air leaks during an inspection, according to Russian state media statement issued earlier Friday. The Russian space agency, Roscosmos, insisted the situation did not pose a threat to the safety of the crew.

The first leak was quickly sealed, Russia’s Zvezda media outlet reported, while work on another problem area continued.

All five astronauts who sought shelter hunkered down inside the same 13-foot-wide (4-meter) SpaceX Crew Dragon capsule that carried the Crew-12 group to the station in February.

Such a move is meant to prepare the astronauts for an emergency escape in the event of disaster. Astronauts routinely take shelter, for example, when the ISS passes near a piece of space junk or the station faces a catastrophic risk.

Problematic leaks were first identified aboard the ISS — specifically within the transfer tunnel called the PrK that connects the Russian-controlled Zvezda module to a docking port — in 2019 and have been a serious, looming issue for years as the rate at which the module has bled air has ebbed and flowed.

The module has largely remained closed off from the rest of the space station to contain the problem.

The issue reached a fever pitch in 2024 as the leak rate worsened, and NASA and Roscosmos, the Russian space agency, appeared to be at odds about the severity of the situation.

At the time, NASA said the leak rate “ranges from 2 to 2.5 pounds (of air) per day above space station baseline.”

On the NASA side, the leaks have been pointed to as a source of potential “catastrophic failure.”

Over the past few years, efforts to repair the leaks have included attempting to patch microscopic cracks — an effort that NASA told CNN in 2024 was made difficult by the fact that the suspected cracks are “very small, not visible with the naked eye and have brackets and pipelines near them, making it difficult to get diagnostic tools into these areas.”

Before the issue reemerged this year, however, it had been months since the leaks caused major concern.

In its Friday statement, NASA said “Roscosmos noted an increase of the previous leak rate to two pounds per day and identified new suspected leak areas in the PrK.”

That culminated in today’s order for all but two Russian cosmonauts, Sergey Kud-Sverchkov and Sergey Mikayev, to take emergency precautions aboard the SpaceX Dragon capsule as Roscosmos further studied the issue before ultimately standing down from attempted fix.

The ISS leaks are adding pressure and scrutiny to NASA’s end-of-life planning for the space station, which is now more than 25 years old and has been continuously occupied since 2000.

While NASA has committed to maintaining ISS operations through at least 2030 — Russia, the United States’ primary partner on the ISS, has not pledged to keep operating its half of the space station past 2028.

It’s not clear how a Russian withdrawal might impact the United States’ operations or the resources required to maintain the station.

NASA and US government officials have repeatedly said that maintaining a space station in low-Earth orbit, the area of space closest to home and hundreds of thousands of miles closer than the moon, is a national security imperative. That’s because China, the United States’ rival in a new space race, is currently operating a new station in the same area, and the ISS or another local space station would serve as a necessary proving ground for the technology that NASA needs to send humans deeper into space — as the agency plans to do under its Artemis program.

The current plan is for the ISS to be replaced by a private-sector alternative. Earlier this year, however, NASA briefly ditched that plan in favor of commissioning a new module for the ISS, apparently with the aim of extending the life of the football-field-size orbiting laboratory. But NASA reversed course just a couple months later, citing input from commercial partners.

— CNN’s Anna Chernova contributed reporting.

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