One of the unexpected facts about space is that it does smell. This came to light when NASA astronaut Mike Hopkins told Reddit readers in a question and answer session in 2014. In relation to the question about space and smell, ABC News notes that the astronaut said: “Space has a smell. And I don’t mean inside the space station.”
Joking aside, he added: “When a visiting vehicle docks with the space station, there is ‘space’ between the two vehicles. Once the pressure is equalized and the hatch is opened, you have this metallic ionization-type smell. It’s quite unique and very distinct.”
Outer space is, in some senses, not really anything at all: simply the void that exists between celestial bodies. However, this depiction ignores the fact that space contains a low density of tiny particles made up from a range of elements.
To answer how space can smell and what it really smells of , Dr. Matt Davenport provides answers to the science behind astronomical aromas and celestial body odors in an entertaining video produced by The American Chemical Society.
So it seems that most of the smell in space comes from dying stars. Other astronauts have described the odor as a bouquet of hot metal, diesel fumes and barbecue. The molecules that provide this scent are polycyclic aromatic hydrocarbons. These molecules traverse the universe in comets, meteors and space dust. To an extent the smell of space depends whereabouts a person is in proximity to different astronomical objects.
Not all astronauts smell the same thing, however. Three-time spacewalker Thomas Jones said returning to the ISS, said that space carries “a distinct odor of ozone, a faint acrid smell”, adding that it is also “sulphurous” (the latter odor giving a whiff of rotten eggs.)
Space is a little different to the Moon, according to Popular Science. From comments from other astronauts the Earth’s satellite carries a hint of spent gunpowder.
