Residents of the ageing International Space Station were forced into their docked spacecraft after an air leak threatened a full-scale evacuation. Photo / Nasa
An air leak aboard the International Space Station left astronauts sheltering in their lifeboats on Friday afternoon, fearing an evacuation might be required.
Nasa and the Russian space agency Roscosmos have been struggling to seal microscopic structural cracks in a transfer tunnel leading to the Russian Zvezda module since 2019.
At its peak, the leak was venting a kilogram of air per day into space, but in recent months the astronauts thought they had the problem under control.
But in May Russian cosmonauts who were unloading cargo from the Progress 95 spacecraft noticed a slow pressure drop in the Zvezda module, and discovered the leak had returned.
On Friday, Nasa ordered five of the station (ISS) crew to shelter inside the docked SpaceX Crew Dragon “Freedom” craft, while the remaining two Russian astronauts attempted another assessment and repair.
It is known as a “safe haven configuration”, where crew members retreat into their docked spacecraft that can immediately evacuate to Earth should the space station suffer a catastrophic failure.
Astronauts were later allowed to re-enter the ISS.
Bethany Stevens, from Nasa’s communications team, said: “The Zvezda service module transfer tunnel 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.”
There have been several scares in recent years, when ISS residents have had to scramble into their shelters, but so far, none have resulted in an evacuation.
In 2024, the decommissioned Russian satellite Resurs-P1 unexpectedly splintered into more than 100 pieces of space junk, and the nine astronauts aboard the ISS were ordered to take cover.
The crew split into several docked capsules – including the Boeing Starliner, SpaceX Crew Dragon, and Soyuz – and waited for roughly an hour while ground teams assessed the debris cloud’s trajectory, before getting the all-clear.
In 2021, a Russian anti-satellite missile test generated a cloud of more than 1500 traceable pieces of debris. The crew were forced into Soyuz and SpaceX Crew Dragon capsules for the first few passes through the cloud before it was deemed to be safe.
An old Soviet weather satellite was seen too late in 2015 to move away and crew were again forced to shelter until the danger had passed. A similar retreat happened because of space junk in 2012 and 2009.
Nasa has previously said that the air leak poses no risk to the crew, but astronauts have struggled to fix it, despite multiple inspections and sealant applications.
Roscosmos has managed the situation by keeping the hatch to the module closed to the rest of the station, and maintaining it at a lower pressure, making small repressurisations as needed.
But it raises questions about the future of the ageing station, which is slated to be retired in 2032.
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