What Does Outer Space Smell Like?

The final frontier smells a lot like a Nascar race-a bouquet of hot metal, diesel fumes and barbecue. The source? Dying stars, mostly.

The by-products of all this rampant combustion are smelly compounds called polycyclic aromatic hydrocarbons. These molecules “seem to be all over the universe,” says Louis Allamandola, the founder and director of the Astrophysics and Astrochemistry Lab at NASA Ames Research Center. “And they float around forever,” appearing in comets, meteors and space dust. These hydrocarbons have even been shortlisted for the basis of the earliest forms of life on Earth. Not surprisingly, polycyclic aromatic hydrocarbons can be found in coal, oil and even food.

Though a pure, unadulterated whiff of outer space is impossible for humans (it’s a vacuum after all; we would die if we tried), when astronauts are outside the ISS, space-borne compounds adhere to their suits and hitch a ride back into the station. Astronauts have reported smelling “burned” or “fried” steak after a space walk, and they aren’t just dreaming of a home-cooked meal.