What Does Space Smell Like?

There is much to ponder in the infinite mysteries of outer space, but…what’s it smell like? It turns out that much, if not all, of the seeing the wonders of space would be accompanied by a distinct aroma — or stench. Space has a smell, but it’s only astronauts (and perhaps your odd corporate CEO with a thirst for interplanetary exploration) who’ll ever get to experience it.

Does space have a smell?

It’s worth noting that no astronaut actually smells space, but rather catches whiffs indirectly. There is no oxygen outside of one’s space suit, meaning an attempt to smell space like you might a scented candle is impossible because it would invariably result in death. Still, astronauts have long been pretty unanimous in their consensus of what they can detect wafting through the void: It smells like “gunpowder, seared steak, raspberries, and rum,” according to a group of NASA astronauts who created a space-themed fragrance last year.

As astronauts explained to the Australian Academy of Sciences, the smells they’ve encountered on space walks are a bit strange:

[A] rather pleasant metallic sensation … [like] … sweet-smelling welding fumes’, ‘burning metal’, ‘a distinct odour of ozone, an acrid smell’, ‘walnuts and brake pads’, ‘gunpowder’ and even ‘burnt almond cookie.’

Or, to hear an actual astronaut tell of their experience, here’s Don Pettit describing space smells, courtesy of Live Science:

The best description I can come up with is metallic; a rather pleasant sweet metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch repairing heavy equipment for a small logging outfit. It reminded me of pleasant sweet smelling welding fumes.

Why does space smell like that?

There’s no unanimous determination, but researchers suspect it has something to do with a “chemical reaction which occurs within the spacecraft during re-pressurisation,” as the AAS writes. It’s surmised by researchers that atomic oxygen attaches to an astronaut’s space suit and enter the craft. When the spaceship re-pressurizes, these single atoms collide with oxygen and then become ozone, which might be the source of the strange smells.

Whatever the source actually is, researchers suspect that the collision of molecules from space with oxygen certain plays a role. One researcher told the Atlantic in 2012 that the smell is likely the product of: “high-energy vibrations in particles brought back inside which mix with the air.”

The Canadian astronaut Chris Hadfield posited a slightly similar guess last year, telling Wired that space is likely odourless in actuality. He suspects “the vacuum of space sucks trace chemicals out of the walls of a spacecraft,” creating the burning, sulphuric smell associated with space, NPR wrote, summarizing the interview. Whatever the true cause is, space will likely be associated with these bizarre odours for as long as humans are donning space suits and blasting off into the cosmos.