According to astronauts returning from spacewalk, outerspace smells like “burning metal” or “charred meat”. The smile is said to linger post-spacewalk too. Scientists believe it could be coming from polycyclic aromatic hydrocarbons found in space which stick to their suit fabric. These are high-energy chemicals released into space by dying stars. They are found on Earth too, emanating mainly from incomplete combustion of fossil fuels.
One explanation is that the smell is due to a chemical reaction which occurs within the spacecraft during re-pressurisation. The process is known as oxidation—similar to burning but with no smoke. In space, atomic oxygen (single atoms) can cling to a spacesuit’s fabric, to tools and potentially even to air-lock walls. When these single atoms of oxygen combine with O? in the cabin during re-pressurisation, they combine to make ozone (O?). It may be this, and not an interstellar aroma, that astronauts are smelling.
Another (slightly sexier) idea is that the odour is due to dying stars. When a star dies it releases a lot of energy. This produces pungent compounds known as polycyclic aromatic hydrocarbons (PAHs), which float endlessly around the universe and assist in the creation of new comets, planets and stars. We have these PAHs on Earth too, you can find them in some foods, and also in coal and oil. PAHs experience high-energy vibrations, which, when combined with air, may be responsible for the unique tang of space.
But there are other smells in space besides, well, space. Comets, planets, moons and gas clouds have their own unique scent too.
Picture Credit : Google
