ISS astronauts briefly shelter in Dragon capsule after air leak worsens in Russian module

The shelter order

At about 9 a.m. Eastern time on Friday, NASA directed five of the seven astronauts aboard the International Space Station to shelter inside the docked SpaceX Crew Dragon capsule. The four members of SpaceX Crew-12 (two Americans, one French, and one Russian cosmonaut) and NASA astronaut Chris Williams were told to don their spacesuits and prepare for a possible emergency undocking. NASA press secretary Bethany Stevens described the move as taken "out of an abundance of caution."

Following new leaks, Roscosmos has elected to proceed with a more extensive repair operation on Friday, June 5.

The order came after the Russian space agency Roscosmos discovered air leaks in the transfer tunnel of the Zvezda service module, known as PrK, while docking a cargo ship. Two Russian cosmonauts remained outside the Dragon to attempt repairs.

A long-standing problem

Cracks in the Zvezda module's transfer tunnel have been a persistent issue for roughly six years. NASA and Roscosmos have tracked the leaks closely, applying patchwork fixes that were not designed as permanent solutions. The hatch to the tunnel was routinely kept closed when not in use to limit risk. According to Spanish outlet LaSexta, the rate of air loss had recently accelerated from about 500 grams per day to nearly one kilogram per day, heightening concern about the structural integrity of the Russian segment.

The cracks have always been a concern that NASA watches very closely.

Repeated efforts to locate and seal the leaks appeared to have succeeded last year, but the leaks resumed last month, prompting Friday's more extensive repair attempt.

Repairs paused, crew returns

About an hour and a half after the shelter order, Roscosmos suspended the repair work. Joseph Zakrzewski, a spokesman at the NASA Johnson Space Center in Houston, said the Russian agency was standing down from activities and conducting measurements only. NASA then instructed the crew to end emergency procedures and return to planned operations aboard the station.

They are doing measurements only, so the crew aboard Dragon will be exiting the safe haven posture.

Roscosmos stated that crew safety and onboard systems were never at risk, and that pressure aboard the ISS remained stable at the intended level. Russian media, citing the Interfax news agency, reported that two air leaks had been identified in the Zvezda module and one had already been corrected while work continued on the second.

Cooperation despite tensions

The ISS is a collaborative project involving the United States, Russia, Canada, Japan, and the European Space Agency. The station orbits Earth at an altitude of roughly 400 kilometers and has hosted continuous human presence for about 25 years. The US-Russia partnership in space has persisted despite severe diplomatic tensions over the war in Ukraine. Friday's incident underscored both the operational risks of an aging orbital platform and the continued, if strained, cooperation between NASA and Roscosmos.

NASA looks forward to working with Roscosmos on a collaborative approach to address the leaks.

This is not the first time ISS crews have faced leaks or been ordered to shelter. The station has been evacuated multiple times in the past due to potential collisions with space debris, and leaks in the Zvezda module have triggered previous repair campaigns. The next repair mission is expected to be a more extensive operation aimed at eliminating the problem permanently.