With space itself being a vacuum, no astronaut has ever had a good sniff and lived to tell the tale. You would expect the vast emptiness of space to hold no smell at all; however astronauts seem to have experienced a different aroma.

Crewmembers of the International Space Station have reported encountering odd smells on the return of spacewalkers. Astronaut Don Pettit has commented: “Each time, when I repressed the airlock, opened the hatch and welcomed two tired workers inside, a peculiar odour tickled my olfactory senses.” And what was that smell? “The best description I can come up with is metallic; a rather pleasant sweet metallic sensation.”

Other astronauts have agreed with this assessment stating that when they return to the safety of their orbital laboratory they have noticed a distinct smell of seared meat and ozone reminiscent of welding fumes. So is this the smell of space? It is likely that this smell comes from the air ducts that re-compress the compartment when astronauts return, or from high energy particles from space interacting with the air.

So while we may not know what space itself smells like, for astronauts, the space experience brings the smell of a freshly seared steak.

Answered by Sophie Allan from the National Space Centre