Ever wondered what outer space smells like? Outer space will amaze you; it is definitely not just a never-ending vacuum. It does have some very distinct smells of its own. So, imagine mixing the scent of hot metal, burnt steak, and gunpowder. Does it sound weird? Well, that’s some of the scents astronauts report after spacewalks.
So how one might wonder – could something as hollow as space have an odor? It turns out that when astronauts return from spacewalks and spill back into the airlock, there is undoubtedly a specific smell clinging to their suits. Once, NASA astronaut Don Pettit described the smell of space itself as being “a rather pleasant sweet metallic sensation,” he equated it to the “pleasant sweet-smelling welding fumes” he sometimes noted while working with an arc welding torch.
What’s more, scientists believe that smell is created out of particles in space—a part of stars that have exploded. Those same compounds are also found in space dust and comets and in some foods on Earth, which explains what the aroma of PAHs smells like: it smells exactly like burnt toast or charred meat—the odor so many astronauts got used to. One biochemist and chief executive of Omega Ingredients who recreated the smell commissioned by NASA, Steve Pearce, found many astronauts described as “hot metal, burnt meat, burnt cakes, spent gunpowder, and welding of metal.”
Another plausible explanation that has been advanced is that of oxygen. Single oxygen atoms stick onto the astronaut’s suit while in space. Upon re-pressurisation inside the airlock, those atoms combine with the atmospheric oxygen to form ozone as O3. This most probably can account for a metallic, acrid smell somewhat similar to that of ozone, though this is what a number of astronauts such as Thomas Jones have described.
It’s thus interesting to note that the smell is not necessarily uniform all across the whole universe. Our solar system itself is one particularly rich in carbon and low in oxygen, hence giving right to smells somewhat along the lines of a car engine running too rich — sloppy and sooty-burnt smells. The outside smell, however, is even more interestingly varied.
Consider Sagittarius B2, a giant interstellar cloud. This cloud is dense with compounds such as ethylformate, responsible for the scent of raspberries and rum. If you’re a fan of the smell of a good raspberry daiquiri, that’s the place to be! Large numbers of such smelly molecules, including hydrogen sulfide (rotten eggs), ammonia, and hydrogen cyanide have been detected by the European Space Agency’s Rosetta spacecraft in the coma of comet 67P/Churyumov-Gerasimenko. Certainly, water vapor and carbon dioxide are the major constituents in any comet, so these odors must have been faint.
More sensational is Saturn’s moon, Titan. Astronomers have discovered that the atmosphere of Titan forms a smelly gasoline-like atmosphere that contains hydrocarbons, which are organic molecules formed from only two elements: carbon and hydrogen. NASA’s Cassini spacecraft detected that nitrogen and methane made a molecule in the atmosphere of Titan, plus a huge linkage of benzene. Just like in gasoline, addition of benzene is able to give a sense of petroleum to Titan.
Even in its serene vacuum, space is full of bright smells and odors that excite and in their turn give scientists the most valuable information about the chemical composition of a certain cosmic environment. Now imagination is freed to the extent that a complex world starts stirring the smells of space yet to be explored.
