In A Nutshell
When astronauts were asked to report on the smell of space, they were actually talking about the smell that followed them back inside on their suits. Space, they said, smells like gunpowder, burnt steak, hot metal, or welding fumes, mostly because of the molecules put off by countless dying stars. Not all space smells the same. So far, scientists have found a comet that smells like cat pee, a moon that smells like farts, and a dust cloud that smells like rum.
The Whole Bushel
Our own planet has some incredible smells happening out in nature, whether it’s the fresh rain, newly cut grass, the ocean breeze, or stagnant water, you immediately know what it is when you smell it. Space, it turns out, is just as clear—without the pleasantries.
While astronauts obviously can’t get a real whiff of space while they’re surrounded by it, they report that there’s an odor that adheres to their suits and enters the interior of the space station or capsule when they come back inside. Astronauts report that it has a definite burnt aroma, likening it to things like hot metal, burnt steak, and diesel or welding fumes.
That smell mostly comes from something called polycyclic aromatic hydrocarbons. A less scientific way to think of them is as the dying breath of some of the galaxy’s biggest stars. As stars collapse, a lot of chemical reactions and combustion goes on inside them, and those reactions put off the scented molecules. But you don’t have to go into space to find them. They’re here on Earth, especially in coal and oil.
They’ve also found that different planets, moons, asteroids, and comets also have their own unique smells based on whatever is in their atmosphere. The European Space Agency’s Rosetta probe recently got up close and personal with a comet called 67P/Churyumov-Gerasimenko, and it was undoubtedly a memorable if vaguely unpleasant experience. Based on the ammonia, hydrogen sulfide, formaldehyde, sulfur dioxide, hydrogen cyanide, and methanol the probe found, researchers were able to define its smell as something along the lines of cat urine, rotten eggs, and bitter almonds.
They also note that the molecules that make the smell are in a low concentration, so it’s unlikely that humans would even be able to really detect it.
The comet isn’t the only one to get the smell treatment. When NASA looked at one of Saturn’s moons, Titan, through a series of spectroscopic tests, they found that they could duplicate the smell back here on our planet. The incredibly precise readings taken by the Cassini probe allowed them to see what molecules were in the thick haze that surrounds Titan.
Titan, according to NASA, smells like gasoline and farts.
That’s not entirely surprising, given that a major component of Titan’s atmosphere is benzene. That’s one of the more deadly elements in cigarette smoke, and the high content helps give Titan’s air that suffocating, poisonous scent.
But, the Max Planck Institute also points out that not all of space might smell like bodily emissions, deadly smoke, or gasoline. When they looked at a dust cloud near the center of the galaxy called Sagittarius B, they found something that might smell like rum.
Or raspberries, depending on your perspective. The cloud contains a high amount of ethyl formate, which is responsible for a good amount of the flavor present in both rum and raspberries. While there are enough other molecules to either dilute the smell (or perhaps change it completely), we’re happy just knowing that somewhere out there, there might be a giant, rum-flavored dust cloud.
Show Me The Proof
New Scientist: Cat stinks of rotten eggs and cat wee, finds Rosetta
Popular Science: What does space smell like?
The Atlantic: What Space Smells Like
Geek: NASA figures out how to smell Uranus (and other planets)
IFL Science: The Center Of Our Galaxy Smells Like Raspberries And Tastes Like Rum