Raspberries? Sparklers? Steak? It never occurred to me to wonder what Space smells like, until I was watching a Space-X Dragon launch, and the commentator described it as smelling like burning metal. But apparently the actual scent of space is a mercurial thing. Just like you might hate the smell of cooking salmon but your mom thinks it’s the best smell in the world, Space seems to smell a little bit different to different people.

It’s easy to imagine that Outer Space is actually a vast nothing in between all the stars and planets and asteroids and therefore devoid of smell. And besides, humans can’t go out into Space without a helmet on. So while they’re floating around out there, they probably don’t smell anything but the Windex they cleaned their helmet with and the fish sticks and astronaut ice cream they ate for lunch on their own breath. (I’m kidding. I’m sure they don’t clean their helmets with Windex!)

It’s a good point, right? How can we really know what Space smells like without taking off the helmet and having a good sniff? Astronauts actually agree that Outer Space does have a very distinctive smell. They know, because after a spacewalk they can smell it in the airlock and on their EVA suits.

While their descriptions differ, in general they tend to describe it as a burning, metallic smell. So what exactly are they smelling?

In my article about How Stars Form I wrote that 98% of matter in Space is made up of hydrogen and helium, two odorless gasses. (1,2) But Space is a big place, and as you know, there is plenty of other stuff out there. There are stars which are mostly hydrogen and helium too, with bits of Space dust thrown in. And when a star goes supernova, it explodes sending out waves of carbon, uranium—even gold! Now carbon, like hydrogen and helium, is also odorless. I couldn’t find any evidence that true gold has a smell either. But uranium is described as having a strong, “acrid” smell. Acrid is an adjective that generally means bitter, and some astronauts have actually used the exact same word to describe the smell of space! (3,4,5)

Not only that, but remember how much hydrogen is out there? Hydrogen is highly flammable, and oxygen makes it burn. (1) But humans need oxygen to breathe, right? So on the space station there is a sort of garage between the habitat of the station and the outside. That's the airlock, and it can be pressurized with oxygen to make it safer for astronauts to come and go from the space station. They pressurize they airlock, fill it with oxygen, open the hatch to the space station, and get inside the airlock. Then they can depressurize it slowly so that when they open the doors to the outside, they don’t get sucked out into space like a vacuum cleaner. That means that inside the airlock, hydrogen and oxygen mix together, and that might be wear the burning smell comes from.

But some scientists who study the universe also think that it should smell a bit like raspberries out there. Yes, you read that right, raspberries, that sweet summer fruit that is perfect in smoothies and pretty much everything else. it’s because these scientists analyzed a dust cloud at the very center of the galaxy and found that it was made of something called ethyl formate, which is actually the thing (it’s called an ether) that gives raspberries their flavor! So the next time you eat raspberries, just imagine, you might actually be tasting the center of the universe. And maybe we need to consider changing its name to the Raspberry Milky Way. (6)

NASA has even commissioned a chemist to design a special perfume based on feedback from all the astronauts. It is called Eau de Space, and they use it to help train new astronauts for exactly what life in Space will be like. (7)

So what exactly does it smell like? Let's hear from the experts: