Space Has a Smell — And Astronauts Know It Well

A vacuum has no smell of its own — sound and odor need molecules to travel through, and a vacuum has none.

But astronauts returning from spacewalks consistently describe the same distinctive smell drifting off their suits: something between burnt gunpowder, grilled steak, and welded metal.

The mechanism: it's likely the scent of dust and residue particles floating outside the station undergoing a chemical reaction (recombination) once they contact oxygen inside the airlock — a process similar to what happens during combustion.

Not something you learned in physics class: the "smell of space" is essentially combustion chemistry, hitched a ride to Earth on a spacesuit.