What Space Smells Like, According to NASA

Published on April 1, 2025

by Harriet King

Outer space is a vacuum, which means it doesn’t have air — and technically, no smell. But if that’s true, how do astronauts describe a distinct scent after spacewalks? According to NASA and seasoned astronauts, space has a surprisingly recognizable odor, especially when returning to the safety of the spacecraft.

So what does space actually smell like? Let’s explore the curious, unexpected science behind the scent of the cosmos — and what it tells us about what’s out there.

So… What Does Space Smell Like?

Here’s what astronauts and scientists have discovered about the mysterious smell of outer space:

Astronauts Report a Smoky, Burnt Scent

Many astronauts who’ve returned from spacewalks describe a smell similar to welding fumes, hot metal, or burnt steak. The scent clings to their suits and equipment when re-entering the airlock.

This is what makes the smell stand out:

Described as metallic, seared, or ozone-like.
Lingering on fabric or tools exposed to the vacuum.
Not experienced directly — only once gear is repressurized inside the spacecraft.
Veteran astronaut Chris Hadfield compared it to gunpowder or ozone after a lightning strike.

It’s Caused by Atomic Reactions

Although space has no atmosphere, high-energy particles and radiation interact with equipment and human surfaces exposed during spacewalks.

Here’s what’s happening at the molecular level:

Free-floating atoms and particles stick to surfaces.
When these surfaces re-enter an oxygenated environment, they react and oxidize.
The resulting chemical reaction produces a distinct smell.
It’s similar to what you’d smell in arc welding or metal machining processes.

NASA Recreated the Smell on Earth

To help prepare astronauts for what they’d experience, NASA worked with chemists to reproduce the smell of space on Earth.

This led to some interesting outcomes:

Simulated the scent using compounds that mimic reactions in space.
Used in astronaut training programs to familiarize new crew members.
Later inspired the creation of perfumes like “Eau de Space” for public curiosity.
Public recreations are based on astronaut interviews and lab chemistry.

The Moon Has a Smell, Too

After the Apollo missions, astronauts also reported a strange smell associated with lunar dust.

Here’s what they noticed:

The dust smelled like burnt gunpowder or fireplace ashes.
It clung to suits and gear when brought back into the lunar module.
Once exposed to oxygen, the dust released a pungent odor.
This supports the idea that chemical reactions after exposure to air create the scent.

Other Celestial Bodies Have “Aromas”

Space may not smell in the traditional sense, but molecules that emit smells can be found in space — floating in gas clouds or on distant worlds.

Here are a few cosmic scents you might not expect:

Interstellar gas clouds contain chemicals that smell like almonds (cyanide), vinegar (formic acid), or alcohol (ethanol).
The center of the Milky Way contains ethyl formate — which smells like raspberries and rum!
Uranus and Neptune likely contain hydrogen sulfide — yes, the stuff that smells like rotten eggs.
We detect these via spectroscopy, not our noses — but the data paints a stinky picture.

The Backstory of the Space Smell Mystery

Reports of space’s smell go back to the earliest NASA spacewalks in the 1960s. Scientists were puzzled at first, but it soon became clear that space particles reacting with re-oxygenated environments were producing the odor.

Over the decades, NASA and other agencies began to study the phenomenon more seriously — both to understand it and to simulate real space experiences for training astronauts.

Why It’s So Intriguing

Smell is one of our most emotional senses — tied to memory, mood, and experience. The idea that something as vast and sterile as space has a scent is deeply fascinating and a little poetic.

It reminds us that even in the void, interactions are happening — and our senses, adapted to Earth, still pick up signals from the stars.

What Most People Don’t Know

Here are a few extra facts about the scent of space that may surprise you:

Spacesuits are never truly “washed” — the scent from space can linger on them between missions.
Astronauts describe it as distinct from any Earth-based smell — unlike anything they’d encountered before.
The ISS has its own smell too — a mix of metal, disinfectant, and life support systems.
Some think the space scent varies slightly depending on location and mission type.

Bonus Fact

The “smell of space” has even influenced pop culture. It inspired fragrances, art installations, and even a Kickstarter campaign to bottle the scent based on astronaut descriptions!

Takeaway

Space might be silent, but it’s not entirely without sensory experiences. Thanks to curious astronauts and brilliant scientists, we’ve discovered that even the void leaves a trace — a scent of burned metal and ozone that hints at the wild chemistry of the universe.

So the next time someone asks what space smells like, you can say: it’s the smell of stars on your suit, the scent of a cosmic spark, and proof that even in a vacuum, the universe leaves a trace.