What happened when inadvertent thruster firing caused the International Space Station to spin completely around? Though the situation was rapidly brought under control, it was a harrowing day for those on the station as well as the ground controllers. Talia from our Planetarium explains what happened, and what it means for the future of this decades-old floating laboratory.

Source article: https://www.space.com/nauka-module-space-station-tilt-more-serious

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ERIC: Sometimes on your space mission, everything goes perfectly the entire time you're above the earth. And sometimes the oxygen tanks rupture, or your spacesuit helmet starts filling with water. Or as we saw last week, the brand new room on your space station makes the whole structure spin uncontrollably. Today on Pulsar, we're going to talk about what to do when things go sideways and how the ISS got back under control. Joining me once again is Talia, the coordinator of our very own Charles Hayden Planetarium here at the Museum of Science. Talia, Thanks for always coming on the podcast when we have space questions.

TALIA: Well, you know I love talking about space.

ERIC: So it's been a rough summer for us space nerds. We love our spaceships. Earlier this summer, the Hubble telescope was in trouble. Now we have a really unbelievable sequence of events at the International Space Station and visitors are asking: is the station okay?

TALIA: The station is actually in good shape. There was an incident but the station is a very well engineered spacecraft, and it seems to have come through with flying colors.

ERIC: Okay, that's great. Getting that out of the way, astronauts are fine, control has been regained. But what happened on the station last week?

TALIA: So last week we added a new module to the space station, Nauka, which was added to the Russian side of the space station. There is a Russian side and an American side to the station.

ERIC: And it's built like a Lego where you can always add pieces.

TALIA: Yes, it's designed to be added on to. And Nauka is a new Russian module and it docked to the space station. And then three hours later it began firing its thrusters.

ERIC: So not the actual rocket engine, just the thrusters that control the spin?

TALIA: Yes, and it used those same thrusters to get itself into position to actually dock with the space station. And then three hours later, for reasons that nobody has quite nailed down yet, they're saying a software glitch, those thrusters begin firing again, while Nauka was attached to the space station. And this made the space station - which is a very, very massive object - start to spin.

ERIC: Yeah, so the space station is the size of a football field. So the thrusters stuck on - I mean, usually you get little bursts of those thrusters to rotate your ship a little bit, a tiny bit, to dock just right and get the angle lined up. But if the thrusters are just going off continuously, I imagine is enough force to get the space station going.

TALIA: I mean, continuously firing thrusters is how you get a rocket into space in the first place, technically, so yeah. So Nauka's continuously firing thrusters put the space station into a spin. It was countered pretty quickly by one of the other modules on the space station, Zvezda. It's another one of the Russian modules. It was the first to detect the movement, and it started counter-firing its thrusters.

ERIC: Was that automatic, that astronauts didn't have to, like, go over and turn valves or anything?

TALIA: Correct. The space station's pretty smart, actually. However, Zvezda versus Nauka, in terms of thrusters, one NASA employee likened it to the ISS bringing a knife to a gunfight. Zvezda could not, it could slow the spin, it could not stop the spin.

ERIC: So still spinning uncontrollably. What was it like?

TALIA: For the astronauts, there really wasn't much going on, it wasn't so fast a spin that they even really noticed the station was spinning by about, at its fastest, about half a degree per second.

ERIC: Okay, and so, huge station, half degree a second. It's not tumbling out of control, the astronauts aren't pushed up against the wall.


ERIC: But, it's important for the station to be oriented just right for a bunch of reasons, right?

TALIA: Yes. One of which is communication. And NASA did lose communication with the space station for several minutes, which could not have been good for the blood pressures of the folks down on the ground.

ERIC: No, I can imagine if you just can't talk to the space station, you're not getting any data and you're in charge of it...it's really harrowing.

TALIA: Yeah, this was this was a very tense day for NASA.

ERIC: How much did it spin? I mean, initially, they said that it spun just a little bit and maybe 45 degrees, enough that communication wasn't really great. It ended up being a little bit more than they said at first?

TALIA: It ended up being a lot more. So 45 degrees was what they initially said. They came back later and said, well, that was incorrect. It was actually a 540 degree spin, which is a full spin and then another half spin, which means by the time the spin was stopped. by the time Nauka stopped firing and they stabilized the station it was on its back, with the side that normally faces space facing earth and the side that normally faces earth facing space.

ERIC: So this is totally unprecedented. The space station and really no space station that I can think of has ever tumbled like this without a good reason, without humans meaning to do it.

TALIA: Certainly not with crew aboard.

ERIC: And so it seems like maybe they don't know exactly what the software glitch was, but it was under control. I mean, did they eventually fix that glitch or, what caused the end of the situation?

TALIA: They could not, aboard the space station, stop Nauka's thrusters on their own, neither could NASA mission control. Because it's a Russian module, it has to be stopped by Roscosmos Mission Control in Russia, which means they had to wait until the station was over Russia to send that signal. At this point Nauka's thrusters have been disabled, and they're fairly certain it's not going to fire again. But it was a very, very tense day. And they were initially concerned because the space station is not designed to tumble like that. And because it is built of a series of things all connected together, they were worried about those connections, they were worried about the modules where the astronauts and cosmonauts live. And they were worried about those giant solar panels that are attached to the space station and provide all its power.

ERIC: Yeah, all that super delicate, I can imagine, you know, a force on one side of an object that's built of lots of little objects is going to create lots of different stress points, have they had to do inspections? Or do they think everything's okay?

TALIA: They think everything's okay. The station is well built, well designed, they were worried about it, obviously, because in the immediate aftermath, nobody knew exactly how much force had been exerted on all of these connections. But all of the solar panels are still attached, all the modules are still connected.

ERIC: Do you think it was more annoying for the astronauts and the controllers on the ground? Do you think it actually was scary in the moment, in the hour or so where these things were happening?

TALIA: I would imagine it was scary in the moment it was happening. I will say all astronauts I've met and spoken to - they don't get, you know, scared, really. They're very well trained in emergency response. And they switch into action mode pretty quickly. So I imagine the astronauts were very like, alright, what do we need to do? What do we need to keep an eye on? But they had no control, they had no way of stopping this. And NASA on the ground, had no control, no way of stopping it. And at one point completely lost communications. I imagine the people on the ground were quite nervous.

ERIC: Yeah, it sounds like some of the testing that they did in the 60s, sending astronauts up and a thruster gets stuck on and your capsule starts spinning so fast that you almost lose consciousness. So luckily, not anything as extreme as that. But I mean, same kind of problem. If your thrusters go off, and you don't have anything to counteract it, that creates spin, and spin is bad.

TALIA: Yes, that was the case on Gemini 8, with Dave Scott and Neil Armstrong, they almost passed out their spacecraft was spinning so fast. And fortunately, again, the astronauts aboard the space station didn't even really notice, their instruments told them they were moving, and they could look out the window and see Earth slowly, you know, rotating.

ERIC: Yeah, it's awesome how automated it is that they didn't look out the window and expecting to see space and see the earth instead and go, ha that's funny, like that window's not supposed to be pointing at the earth, that the station itself is automated and has systems and backups and protocols for, hey, we're not in the right orientation. Hey, we're spinning and alerting people on the ground, people in space. It's really amazing.

TALIA: Oh, yeah. It is an incredibly well designed facility. There's a reason why we call it one of our greatest engineering achievements, not just in space, just in general.

ERIC: And we're coming up on 21 continuous years of people being on the space station, not just any space station, this space station. So if a baby was born on the space station, that first day, it would be able to get a drink at the space station bar if there was one. Next month will be 21 years without a gap of people being in space, what's the future of this space station?

TALIA: So it's a little up in the air because we're not sure, Russia has made noises about potentially wanting to end their commitment to the space station. It is expensive for a space agency to be invested in the space station. And Roscosmos does not have the financial support that NASA does. So they have made sounds about pulling out. But every time they sort of make that sort of statement, they're also like, well, maybe not because this is a major achievement for them. Coming up in the very near future, the space station is about to become a movie star. Russia is sending an actress and a director to the space station this fall to film part of a movie. And interestingly enough, the two cosmonauts that are aboard the space station right now are going to have to be actors in that movie, because the director and the actress have to work with what's up there. And what's up there is a pair of cosmonauts.

ERIC: Can't send extras up, you have to use the real cosmonauts.

TALIA: Yep. So they released some details about the storyline of that. And at least one of the cosmonauts is going to have to play a major role in the movie.

ERIC: That's too funny. Well Talia, thanks for being on the podcast and making me feel better about what's up at the International Space Station.

TALIA: My pleasure, Eric, I'm always happy to talk about space.

ERIC: You can check out more of our awesome digital content about space including a whole series of videos about making it to Mars at mos.org/planetarium. That's also where you can look up showtimes for our Charles Hayden Planetarium so you can come learn about space and ask your questions to our awesome planetarium staff in person. Until next time, keep asking questions.

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