Air leaks on the International Space Station

Astronauts have now returned to the International Space Station after repair work was carried out on persistent air leaks on the Russian part of the satellite. Five of the space station’s crew members were ordered to shelter in SpaceX’s shuttle craft, and brace for potential evacuation. Meanwhile, the two remaining Russian cosmonauts attempted to plug the air leaks. Rachael Ralph asked Richard Hollingham from the Space Boffins to bring us up to speed…

Richard - There was a lot of drama when suddenly we got this message from NASA saying they've evacuated five astronauts into the SpaceX capsule, sealed them in, and you had two Russian cosmonauts fixing this leak. So, you know, this sort of came out of nowhere, but actually it really didn't come out of nowhere because this particular module is called the PRK, which connects to the Zvezda Service Module on the International Space Station, has actually been leaking since 2019. So, it was really unexpected that they suddenly decided to fix the leak now, and it looks like they've at least partially fixed the leak on the space station. They've used something, I love this, it's actually a patented sealant called Germatol 1, which is essentially some sort of sealant and cloth that they use to put over any potential holes in the spacecraft. At the moment, everything seems to be stable.

Rachael - So like you said, these air leaks started in 2019, so what's actually prompted this heightened concern and caused the evacuation of the astronauts?

Richard - I don't think we're entirely clear other than the Russians decided to fix it now, because the leaks don't seem to have been getting any worse, or at least as far as we know. But this is old, this spacecraft now. So, this was designed in the 1980s, it was going to be the successor to Mir. It was built in the 1990s, it's been in space for almost 26 years, so it was launched in July 2000. And, you know, it's a really harsh environment there, there's all sorts of particles, there could also have been errors. It's being docked with constantly, this is a tunnel leading to a docking port. So it's under all sorts of strains. And I mean, the bottom line is, it's getting old, it's getting worn, and how much longer it's going to last is the big question.

Rachael - I presume that this emergency evacuation kind of demonstrates how seriously the air leaks were taken. But what would have happened to the other two crew members who stayed on board to fix the leaks if they needed to be evacuated as well?

Richard - It's important to understand that these are leaks, these are tiny leaks, it's a small amount of air leaking out. So, it's not catastrophic, it's nothing like, you know, the film Gravity, where suddenly the spacecraft's bombarded by all sorts of stuff and there are holes everywhere. It's really nothing like this. So, this was a contingency. And I think it shows the care and the attention that the space agencies put into the welfare of the crew. I mean, it was really an abundance of caution here. And if something had gone really badly wrong, well, everyone can get quickly to a spacecraft. And the point of putting the astronauts in the spacecraft was they could undock from the space station if there was a major problem and just get out of the way. Those two crew that were fixing the leak, yes, they were probably under more peril, not really, because, you know, it's unlikely that it would suddenly rupture. So, they were probably at risk the most. But if it had got worse, they could just get out, shut the door and get into their Soyuz capsule and get off the space station. So, you know, it's really an abundance of caution. I think it shows that astronaut welfare absolutely comes first here.

Rachael - So like you said, astronaut welfare does come first, and these astronauts live in a perilous environment. So why haven't the leaks been properly repaired before? I guess they've been partially repaired, like you said, especially now, but why not fully?

Richard - It is absolutely a perilous environment. 400 kilometres above the Earth going at 27,000 kilometres an hour in the vacuum of space. And it's low Earth orbit. So there's lots of other debris sort of spinning around there. And it's an old space station. I mean, I wouldn't want to do it. The leaks themselves, we're probably going to see more there, you know, sort of hairline fractures. The bigger concern would be if a large piece of space debris hit the space station, or one of these really started to rupture. I mean, they could seal this area off. Think about like a submarine, where you have hatches between the various sections, or ships as well have that. So, you know, they can seal off sections of the space station if there is a bit more of a problem. I think we are going to see more and more of these leaks over the next few years. At the moment, the plan is to take the space station out of orbit, well, you know, push it out of orbit in 2030, maybe 2032. But it's a question of kind of keeping it going in the next four or five years.

Rachael - So, with the plans to decommission the ISS in 2030 or 2032, are there plans to potentially have a replacement space station at all?

Richard - There is no space agency plan to have a replacement space station. But there are plenty of private companies and that's kind of the point. So, NASA, who is leading on all this, wants to sort of make way for small private operators of space stations. And there are several being built by several companies, whether they'll all fly, it's unclear at the moment. But that is the plan. So, we will see the end of the International Space Station. So, this great international endeavour, where you've still got, you know, American astronauts working alongside Russians, despite the war in Ukraine. And so that's going to be replaced with, I think, small private space stations, maybe more robotic craft. And then NASA is pushing forward and putting all its efforts into getting astronauts back on the Moon.