A worsening air leak aboard the International Space Station prompted five astronauts to take shelter and prepare for evacuation for roughly two hours on Friday as Russia attempted to fix a crack on its portion of the orbital laboratory, NASA said.

Pictured above: Russian cosmonaut Andrey Fedyaev, NASA astronauts Jack Hathaway, Jessica Meir, and ESA astronaut Sophie Adenot.

The four astronauts of NASA’s Crew-12 mission aboard the station — two Americans, a French astronaut and a Russian cosmonaut — along with a fifth US astronaut, Christopher Williams, were ordered by NASA mission control at 9:04 a.m. ET (1304 GMT) on Friday to enter their SpaceX-built Crew Dragon spacecraft docked to the station, NASA spokesperson Bethany Stevens said.

NASA reversed that order roughly two hours later and told the astronauts they could return to the station as the agency and its Russian counterparts examined the rate of leaking air.

The leak is not entirely new. NASA and Roscosmos have been tracking small air leaks in the Russian Zvezda module for years, but Friday’s incident escalated after the leak rate reportedly doubled, prompting NASA to briefly move astronauts into their docked SpaceX capsule as a precaution.

Air leak triggers rare ISS safe-haven order

NASA and Russia's space agency Roscosmos, the station's two primary operators, have debated for months over the cause and potential fixes of small air leaks aboard Russia's Zvezda service module, a key structure of the ISS, a football-field-sized orbital laboratory where astronauts live and work in space.

“Following new leaks, Roscosmos has elected to proceed with a more extensive repair operation on Friday, June 5," said NASA Senior Advisor & Press Secretary Bethany Stevens in a post on X.

"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 communications."

Roscosmos said on Friday that its experts had detected two leaks aboard the ISS but that there was no immediate threat to the crew. The first leak was quickly sealed, and preparations were underway to seal the second one, Roscosmos said, adding that there was no threat to the spacecraft's systems.

The air leaks have been relatively minor in recent months but escalated on Friday from a pound of air per day to two pounds, according to a senior NASA official who asked not to be named.

Seven astronauts remain aboard ISS as repairs continue

The ISS is currently home to seven astronauts from two missions, including the Crew‑12 team — NASA astronauts Jessica Meir and Jack Hathaway, European Space Agency astronaut Sophie Adenot, and Roscosmos cosmonaut Andrey Fedyaev — who arrived in February.

The other crew of one US astronaut, Christopher Williams, and two cosmonauts, Sergey Kud-Sverchkov and Sergei Mikayev, arrived in November.

Kud-Sverchkov and Mikayev, who did not execute evacuation procedures, were planning to use a saw to reach an area where they believed they could access the crack leaking air, the NASA official said.

NASA officials disagreed with this method, the NASA official said, prompting mission control in Houston to order safe-haven procedures.

Stevens said NASA reversed the safe-haven order and told astronauts they could return the space station once Roscosmos paused its efforts to repair the crack. "We look forward to working with Roscosmos on a collaborative approach to address the leaks," she said.

Safe-haven orders are rare on the International Space Station, though pieces of space debris that risk colliding with the ISS and smaller changes in air leak rates have triggered the process in recent years. Astronauts have never had to evacuate the ISS in its 27-year history.

US lawmakers push to extend ISS lifespan

Legislation is before the US Congress that would extend the planned life of the space station for two years, until 2032, to give companies more time to develop a replacement.

The bill has the backing of Senator Ted Cruz, a Republican, and Senator Maria Cantwell, a Democrat - the chair and ranking member, respectively, of the Senate Committee on Commerce, Science and Transportation.

The legislation is part of the committee's focus on rivaling China's growing footprint in space. Leaders in the US Senate and House of Representatives are working to reach consensus on the proposed legislation.

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