What Does Space Really Smell Like?

1979's "Alien" taught us that "in space no one can hear you scream," which, according to a 2019 experiment, is true. That makes Ridley Scott's timeless sci-fi horror film a frightening science lesson as well. But so much about space is alien to humans that there's always more to learn about how awful it is. People who've had the honor of traveling up above the world so high like a diamond can tell you that space can do bad things to a body, including ruining their eyesight, impairing their immune system, causing their fingernails to fall off, and reducing their bone density. Simply put, space stinks. But does it also smell bad?

Popular Science points out that "a pure, unadulterated whiff of outer space is impossible for humans" because it's a vacuum, which sucks even more than the thought of space stinking. However, astronauts on the International Space Station who step outside for some fresh non-air have come back with the smell of space on their suits. According to them, it smells like "burned" or "fried" steak. When a fragrance maker tried to reproduce the odor of the universe for a simulation, "astronauts compared it to spent gunpowder." 

Why does space smell like that?

So where does that collection of stenches — poetically described by Popular Science as "a bouquet of hot metal, diesel fumes and barbecue" — actually come from? Death. Specifically, dying stars produce polycyclic aromatic hydrocarbons as they combust, and these molecules are strewn about the universe. Luckily, no one can hear the stars scream as they literally burn to death.

But space only "mostly" smells like star death. What's the rest of it? Who knows? The haunting darkness of space also contains bizarre objects like urine crystals, animal corpses, and Elon Musk's Tesla Roadster, among other things. Maybe all those different things smell extremely different from one another and influence the stink of space in their own infinitesimally tiny way. (The Roadster presumably adds a Musky, marijuana-y aroma.)