What The Milky Way Smells Like, According To Scientists

The way humans construct a vision of reality, a model of the world, is through our five core senses: sight, hearing, touch, taste, and smell. While some believe that we rely mostly on visual and hearing information, our brains rely on all senses to give us the big picture. But all that goes out the window in space.

Science tells us that there is no air in space, only vacuum, and just like sounds need a medium to travel, so do smells. While astronauts can't just stick their heads outside the airlock on the International Space Station and take a sniff, they have reported encountering some intriguing smells in space – reports that NASA has kept track of. Astronauts say that space smells rather metallic with a touch of seared meat.

NASA has also done experiments on how flowers smell on the International Space Station, learning that even though flowers produce fewer oils in space, the oils that are produced tend to have a stronger smell than those same oils on Earth. Additionally, studies have found that under the influence of zero gravity, bodily fluids move to the head, which can result in "alterations in the senses of taste and smell." With all of that in mind, it begs the question: What, if anything, does the Milky Way smell like?

In 2009, a study published in Astrophysics revealed that the Milky Way galaxy smells like rum. The finding was confirmed by other studies years later, per Astrophysical Journal Letters. These scientific studies focused on organic molecules found in Sagittarius B2 — a giant molecular cloud of gas and dust located about 390 light-years from the center of the Milky Way — where stars are born. The findings revealed that ethyl formate and n-propyl cyanide were among the interstellar chemical elements found in the cosmic cloud. Ethyl formate gives raspberries their taste and rum its distinctive smell.

"It does happen to give raspberries their flavor, but there are many other molecules that are needed to make space raspberries," Arnaud Belloche from the Max Planck Institute for Radio Astronomy in Bonn told The Guardian. One of the main reasons why studies search for cosmic chemical elements' signatures is to find amino acids, which are known as the building blocks of life.

The findings of these studies, which indicate space smells like raspberries and rum, have also been confirmed by astronauts and what began as a strange NASA project. On June 30, 2020, CNN reported on the Kickstarter project of Steve Pearce, once hired by NASA to do a space smell study. Eau de Space has sold more than half a million dollars in perfumes and only has two products: Eau de Space (the Smell of Space) and Eau de Luna (the Smell of the moon). Eau de Space says that decades ago NASA made a fragrance just for astronauts to know what space smelled like before going up.

According to Pearce, the fragrance was based on astronauts' descriptions which included smells of seared steak, welding, raspberries, and rum. The smell of the moon, according to astronauts and Eau de Space, has a touch more of a gunpowder scent in it. The obsession with smell in space is deeply linked to making our connection and understanding of the cosmos more human and will likely continue as humanity ventures deeper into the universe because our five senses are what make humans, humans.

Scientists on the International Space Station who participate in spacewalks can catch a whiff of the Milky Way as they're wrapping things up. According to NASA astronaut Don Pettit, astronauts who go out spacewalking return to the ISS with a unique smell. "I had the pleasure of operating the airlock for two of my crewmates while they went on several space walks," Pettit said in a NASA blog post from 2003 (archived link). "Each time, when I repressed the airlock, opened the hatch and welcomed two tired workers inside, a peculiar odor tickled my olfactory senses."

Pettit went on to explain that after searching for the source of the smell, he realized that it was coming from the astronauts' spacesuits — the ones they just wore on their spacewalk. What does it smell like? "The best description I can come up with is metallic; a rather pleasant sweet metallic sensation," Pettit said. While that may not help us Earth-bound humans place the smell, Pettit did add that it reminded him of "pleasant sweet smelling welding fumes."

So, astronauts who spend time in the vacuum of space return with a metallic smell, but why does this happen? One potential explanation is that atomic oxygen particles attach to astronauts' suits during spacewalks and then turn into ozone after combining with the molecular oxygen particles aboard the space station. While it may not be the most thrilling explanation, that could indeed explain what Pettit smelled during his time on the ISS — and it could be the closest we'll get to defining the smell of the Milky Way.