ISS Crew Prepares for Emergency Evacuation Due to Air Leak

Five of the seven crew were directed to go into the docked SpaceX shuttle Dragon "Freedom" on Friday afternoon and were braced for a potential evacuation. Meanwhile, two remaining personnel - a pair of Russian cosmonauts - attempted to repair a part of the Russian segment of the ISS, where the leaks had started increasing on Monday. The repairs were paused and the crew ordered back onto the ISS by Nasa on Friday afternoon. Jessica Meir, Jack Hathaway, Sophie Adenot and Andrey Fedyaev, who arrived on the ISS in February, had been sheltering on the docked ship, along with another astronaut Chris Williams. They had been told to put on their spacesuits so they were ready to undock and return to Earth at short notice. The Dragon effectively functions as a lifeboat - attached to the station but ready to detach the moment the order is given. The trigger for the order was a worsening air leak in the transfer tunnel, known as PrK, leading to a section of the Russian segment of the station called the Zvezda service module. Retired Canadian astronaut Chris Hadfield, who was a commander of the ISS in 2012, said it had always leaked around half a pound of pressure a day. "When you have an area that's leaking a little more, you get up to a pound a day, maybe a pound a half or even two, then we hit a threshold where, okay, we've got to do something about this," he told BBC Newshour. "You're always one breath away from having to take shelter somewhere if the station has a problem. It's just a matter of fact of living on board a spaceship." It is not the first time the station has had to deal with this latest leak - the cracks responsible have persisted on and off for around six years. However, following the arrival of a Russian cargo ship last month, the Russian space agency Roscosmos noticed a fresh slow pressure drop in the tunnel, prompting the decision to move beyond patchwork fixes and attempt a more extensive repair operation on Friday. But it was the method they were planning to use that prompted the order to take shelter, according to news agency Reuters. Kud-Sverchkov and Mikayev were said to be using a saw to try and get into an area to access the crack that was leaking air. Nasa disagreed with the method they were using and mission control in Houston ordered five crew to take "safe-haven" procedures on the Dragon ship.