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Mir taught us a lot, but most days, it was also a mess of mold and electrical problems... even when it wasn’t literally on fire.

Host: Reid Reimers
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Right now, there are people living and working in an artificial satellite about the size of a football field, zooming around the earth at 26,000km/hour.

Which is awesome! But we didn’t learn how to do that overnight.

There were a few different space stations before we built the International Space Station. And the one that stuck around for the longest was Mir, a space station launched by the Soviet Union in the 1980s. Mir was compared to everything from a graceful dragonfly to a hedgehog to a death trap, and for good reason.

It taught us a lot and was home to tons of accomplishments, but most days, Mir was also a mess of mold and electrical problems ... even when it wasn’t literally on fire. Mir wasn’t the Soviet Union’s first space station. Instead, it was designed to succeed the Salyut program, which ran from the 1970s to the 80s.

Like the ISS, Mir was modular, meaning it was launched in pieces and assembled in orbit over several years, starting in 1986. It’s hard to translate its name into English, but Mir means something along the lines of “world”, “village”, and “peace”, and many cosmonauts remember it fondly. But by the time Americans began joining the missions in 1995, the station was an accident-prone mess.

For one thing, there was never enough on-board storage, and there also wasn’t enough room on the ships returning from Mir to carry all the garbage away -- so over time, the place became packed with junk. Then there was Mir’s microbe problem. According to some astronauts, after years of people continuously living there, the place got a little … smelly.

Scientists knew the station might have basically turned into a giant, orbiting petri dish, so they had astronauts collect some samples. And it was worse than they ever imagined. When astronauts removed a few instrument panels, they were greeted by floating basketball-sized globs of filthy water, where unspeakable things were growing.

The water had gotten trapped behind the panels, and the air back there was nice and warm, making it a tropical paradise for mold, mildew, and bacteria. Besides the fact that that’s totally disgusting, it was also a risk to the crew’s health in more ways than one, because some microbes could have corroded steel and threatened the structural integrity of the station. Unfortunately, humans are always carrying microbes in our body, so we can’t leave all the germs back on Earth, and even the ISS has had some problems.

But after Mir, better monitoring techniques were developed to help astronauts stay on top of things, and keeping the station in working order has also helped. Mir had periodic power outages, which helped the heat and humidity climb to those more microbe-friendly levels. Since Mir, we’ve also gotten a lot better at steering resupply modules, which visit the ISS to drop off supplies and experiments.

Once in 1994 and again in 1997, piloting problems caused modules to bump into Mir, and the accident in 1997 was especially bad. Because of some risky piloting maneuvers, there was a major crash that seriously damaged the station’s Spektr module, a science lab designed to monitor Earth from above. The hull was breached, and even though astronauts were able to patch the hole and stop air escaping, Spektr was never fully usable again.

Now, crashing something into your space station is never a good sign, but there was one accident that was even more dangerous: a fire. A fire in space is a lot scarier than one on Earth, because you can’t just run outside and get away from it: You’re trapped in a small, enclosed area with a burning inferno. This one could have injured or even killed the people on board, but luckily no one was badly hurt.

The blaze came from a faulty oxygen generator. These devices, informally called candles, were about the size of a spray paint can, and they produced oxygen by burning lithium perchlorate, a salt made of lithium, chlorine, and oxygen. Usually, candles are pretty safe, and they’re still used as oxygen backups on the ISS today, but this one malfunctioned and burned out of control.

It was so hot that one astronaut reported seeing what he thought was dripping wax -- but it was actually molten metal because the fire was so hot. Thankfully, the blaze wasn’t pointed at the station’s outside walls, where it could have damaged the hull. And the crew had recently cleaned up the mess in the area, so they had an escape path and could put out the fire.

Afterward, quality control of the candles was improved so something like this would never happen again, and the ISS now takes multiple precautions if a fire is detected, like cutting power and venting the oxygen in that area. Finally, after 15 years of triumph and chaos, Mir was sent back to Earth in 2001, where it cannon-balled into the Pacific Ocean. Even though it had its rough days, Mir was only designed to fly for five years, so it’s pretty impressive that it lasted as long as it did.

It outlived the Soviet Union and stuck around long enough to see the ISS succeed it. And a lot of the reason the ISS is so successful today is because of lessons learned on Mir. So even though we might sometimes poke fun at that orbiting struggle bus, it also set records, housed countless experiments, and changed the way we live in space today.

Thanks for watching this episode of SciShow Space! If you want to learn more about early space stations, you can check out our episode about Skylab, America’s first space station. And for more videos every week, you can head over to and subscribe.