While in orbit, astronauts protect themselves inside vehicles, suits and space stations, “because direct exposure would of course kill them.”
Therefore, no one has ever smelled space directly. However, after returning to Earth, astronauts often describe unexpected odors similar to burnt steak and spent gunpowder.
Astronauts regularly smell a whiff of a unique scent when their helmets are removed, and their compatriots also notice this scent emanating when the airlock doors are opened.
“Space definitely has a different smell than anything else,” NASA astronaut Dominic Antonelli said after a “spacewalk” in 2009.
In general, astronauts often compare the smell of space to the smell of “hot metal, burnt meat, burnt cake, spent gunpowder, welding metal, and also the smell of ozone.”
There are a number of possible explanations for this smell, and it has to do with the oxygen floating around the International Space Station. Ultraviolet radiation from the sun can split oxygen molecules, made up of two oxygen atoms, into single oxygen atoms.
