Space station crew briefly moves to "safe haven" amid concerns over leaks

Out of an abundance of caution, NASA on Friday briefly directed five of the seven crew members aboard the International Space Station to wait inside the docked SpaceX Crew Dragon "Freedom" spacecraft — known as a "safe haven" — as two cosmonauts began work to address two small air leaks in a compartment at the rear of the Russian Zvezda module.

Roscosmos, the agency that manages the Russian segment of the station, said the complex was in no danger, that one leak had been sealed and that preparations to seal the second were underway. But it was not immediately known when cosmonauts Sergey Kud-Sverchkov and Sergey Mikaev would attempt the additional repair.

In any case, with that work apparently completed for the day, their station crewmates — Crew Dragon commander Jessica Meir, Jack Hathaway, European Space Agency astronaut Sophie Adenot and cosmonaut Andrey Fedyaev, along with NASA Soyuz astronaut Chris Williams — were told they could exit the Crew Dragon and return to normal work.

"Roscosmos has paused Friday's structural repair efforts inside the Zvezda service module transfer tunnel, known as PrK, as more measurements and data (are) assessed," a NASA spokeswoman said on the social media platform X.

In an updated statement Friday evening, NASA said it "strongly supported" the decision to pause the repairs, and "as a result, following that decision, Crew-12 and Williams ended their safe haven activities and returned to normal operations aboard the orbiting laboratory." 

Small leaks have been monitored since 2019 in a tunnel segment at the back end of the space station, where visiting cargo and Soyuz crew ships dock. But efforts to pinpoint and repair the source, or sources, of the leakage have had mixed results. The compartment is periodically sealed off and kept at lower pressure to minimize air loss.

"NASA and Roscosmos have worked together to identify the root cause while Roscosmos has been applying leak mitigation measures, including temporary and permanent sealants," NASA said in its statement. 

Roscosmos posted an update later Friday saying "the situation does not threaten the safety of the crew and onboard systems; pressure on board the ISS is stable and maintained at the calculated level."

The statement said that earlier in the day, when flight controllers were bringing the compartment up to the station's normal air pressure level, specialist "detected a leak." During an inspection, the cosmonauts "discovered two potential air leak locations."

"The first location was promptly sealed by applying the first layer of (a) two-component sealing compound," Roscosmos said. "The second location is situated on the conical part of the (compartment). Work is underway to prepare for its sealing."

In its statement Friday evening, NASA said that Roscosmos found the leak rate had increased to two pounds per day. NASA said that Roscosmos subsequently cut a bracket "to better access an area identified as a possible leak source for further inspection, using a method that could have resulted in elevated risk to the structure in the area."     

There was no immediate word on when the Russians might press ahead with that effort or whether the leakage detected Friday might be related to earlier leaks in the compartment.

The NASA spokeswoman earlier said agency flight controllers directed the other crew members to shelter in the Crew Dragon capsule after Roscosmos "elected to proceed with a more extensive repair operation."

"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," she said.

"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 solution."

As the five crew members were gathering in the Dragon, mission control at the Johnson Space Center in Houston told them internal television cameras had been turned off, normal procedure when privacy might be needed.

"You just couldn't watch any more of this, huh?" Meir joked.

"We love being on board with you guys, but we wanted to give you your privacy while you're having family camp-out day in Dragon," mission control replied.

As it turned out, the crew's "camp-out day" was cut short when the repair effort was called off.