Toilet bags and eau de antiseptic and garbage: Just how filthy is the International Space Station?

Let’s face it: Floating 350km above Earth in a sealed space station for months doesn’t sound like the most sanitary venture

After all, even inhabitants of the junkiest dwellings on land have the benefit of occasional fresh air. Earlier this year, astronaut Scott Kelly described the International Space Station’s singular aroma as something akin to a mixture of antiseptic and garbage.

There’s no positive way to spin that one. But how clean (or dirty) is the International Space Station? New research on the spacecraft’s unique bacterial population contains some reassuring news - and a few icky insights.

WATCH: Take a tour of the ISS toilet with astronaut Samantha Cristoforetti

In their quest to characterise the cleanliness of the ISS, scientists from NASA’s Jet Propulsion Laboratory got the literal dirt on the station. Astrobiologist Kasthuri Venkateswaran and his colleagues studied a HEPA filter that had been on the craft for 40 months (there are 21 total on the craft at any given time).

They also got their hands on two bags of dust from the ISS vacuum cleaner. It might not sound glamorous, but a daily sweep is one of the crew’s many tasks.