NASA directs its ISS crew members to board spacecraft amid leak repair attempt

By Jackie Wattles, Deblina Chakraborty, CNN

(CNN) — Five astronauts were forced to seek shelter aboard a spacecraft attached to the International Space Station as their crewmates worked to assess a leak in the Russian-controlled side of the orbiting laboratory.

The cracks and leaks on a portion of the space station operated by Russia, located in a transfer tunnel between a module called Zvezda and a docking hatch, have been a known concern for some time. But the NASA statement suggested the situation had potentially worsened.

“Following new leaks, Roscosmos has elected to proceed with a more extensive repair operation on Friday, June 5,” Stevens said in the post. “Out of an abundance of caution, NASA has directed all four of the agency’s SpaceX Crew-12 members and NASA astronaut Chris Williams to assume an elevated safety posture in the Dragon spacecraft while the repair is underway.”

The order to seek shelter, however, was lifted later Friday morning as the Russian space agency “paused Friday’s structural repair efforts … as more measurements and data is assessed.”

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

Those who sought shelter 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.

Cosmonauts discovered two potential air leaks during an inspection, according to Russian state media. The Russian space agency, Roscosmos, said the situation does not pose a threat to the safety of the crew.

“While pressurizing the Zvezda module’s transfer chamber (TBC) to the International Space Station’s pressure, specialists from the ISS Russian Segment’s main operations team detected a leak in the TBC,” a Rosmosmos statement reads, according to state media.

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

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.

A long history of leaks

Problematic leaks were first identified aboard the ISS — specifically within a transfer tunnel called the PrK connecting 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.

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.”

However, after nearly a year without causing major issues, problematic leaks recently reemerged — culminating 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.

An uncertain future

The problem is 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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