NASA directed five of the seven astronauts aboard the International Space Station (ISS) at 1304 UTC, Friday (June 5) to shelter in the docked SpaceX Crew Dragon 'Freedom' spacecraft as a precautionary measure while two Russian cosmonauts attempted repairs on a worsening air leak.
"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," NASA spokesperson Bethany Stevens said via X this morning. The order was lifted roughly two hours later after Roscosmos paused repair efforts to take additional measurements, confirming the situation did not immediately threaten crew safety.
The five astronauts -- Jessica Meir, Jack Hathaway, and Sophie Adenot (European Space Agency) from SpaceX’s Crew-12 mission, NASA astronaut Chris Williams -- donned spacesuits in the Dragon, to be ready for rapid evacuation. Russian cosmonauts Sergey Kud-Sverchkov and Sergei Mikaev remained in the Russian segment to perform the repairs. Their designated escape vehicle is the separately docked Soyuz MS-28 spacecraft.
The leak is located in the PrK transfer tunnel connecting the Russian Zvezda service module to a docking port. This area has suffered from microscopic structural cracks for over six years, with NASA previously classifying it as a top safety risk. Russia's space agency, Roscosmos, manages it through operational mitigation measures and periodic partial-repair efforts.
Stevens wrote "The Zvezda service module transfer tunnel, known as PrK, has suffered from cracks and leaks for some time, and has been mitigated by Roscosmos as much as possible to date. The cracks have always been a concern that NASA watches very closely.
"NASA and Roscosmos have been working to determine the root cause of the cracks, and Roscosmos manages the issue through operational mitigation measures and periodic partial-repair efforts. Following new leaks, Roscosmos has elected to proceed with a more extensive repair operation on Friday, June 5.
"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. We continue to work with our Russian counterparts, along with the rest of the international community that supports the space station, to arrive at a more permanent resolution."
After a period of stability earlier in 2026, sensors detected a fresh pressure drop following the arrival of the Progress 95 cargo ship in May. By early June, the leak rate had escalated to approximately one kilogram of air per day, prompting Roscosmos to attempt a more extensive repair operation using sealant and tools.
NASA lifted the shelter order about 2 hours later. "Roscosmos has paused Friday’s structural repair efforts inside the Zvezda service module transfer tunnel, known as PrK, as more measurements and data is assessed," Stevens wrote at 1457 UTC. "Given this development, NASA has instructed the crew members inside the Dragon spacecraft to end the safe haven procedures and return to planned operations aboard the International Space Station. We look forward to working with Roscosmos on a collaborative approach to address the leaks."
The PrK leak highlights the space station's advanced age. Construction of the complex began in 1998, and It has been continuously occupied by rotating astronaut crews since November 2000. And Zvezda is one of its older pieces: The module launched to orbit in July 2000. The orbital lab will operate potentially until 2032, giving more time for private successors to get up and running in low Earth orbit.
The four astronauts of SpaceX's Crew-12 mission -- Meir, Hathaway, Adenot and Fedyaev -- arrived at the International Space Station (ISS) in mid-February for a six-month stay. Williams flew with two crewmates on the Soyuz — Kud-Sverchkov and Mikaev.
