(Web Desk) - Astronauts aboard the International Space Station (ISS) have been told to prepare for an urgent evacuation.
The ISS is aging, and is due to be retired by the end of the decade.
However, Nasa and its Russian counterpart Roscosmos have reported 50 "areas of concern" on the orbital outpost, which include cracks and leaks, one of which has been leaking oxygen since 2019.
The five-year-old leak is present in the Russian service module, adjacent to a hatch, which was installed in 2000.
In a recent report from Nasa's Office of the Inspector General (OIG), the agency dubbed it a "top safety risk", escalating the threat rating to five out of five.
Nasa is closely monitoring four cracks and 50 other "areas of concern" on the ISS.
While astronauts can cover the cracks with patches or sealant, these are largely temporary solutions.
If the leaks get significantly worse, and start to present a danger, astronauts can close off the tunnel completely.
Although that will mean losing a valuable docking port used by Progress and Soyuz spacecraft.
"We have conveyed the seriousness of the leaks multiple times, including when I was in Russia earlier this year," Nasa's associate administrator, Jim Frees, told the Washington Post.
For now, Nasa has agreed with Roscosmos to shut the hatch to the Russian module in the evenings.
Nasa astronauts will also remain on the US side of the station to be close to their escape vehicles, should an evacuation be necessary.
Space debris is increasingly a threat to the ISS, which is roughly the size of a football field, and therefore an easy target.
The outpost occasionally has to move its orbit to dodge larger pieces of space junk.
In June, astronauts aboard the ISS were forced to take cover when a defunct Russian shattered into 200 metal pieces in orbit.
However, this is not always possible to dodge debris, particularly with the smaller pieces.
Shards of metal no bigger than a fleck of paint can do the ISS enough damage that astronauts have to spend weeks repairing it.