How can nothing have a smell? When you think about it, space, in its abundant emptiness should really not have any odour at all. I mean, what is there to smell in a vacuum, other than the absence of everything? And we really wouldn’t encourage anyone lucky enough to visit outer space to take off their helmet and try to take a whiff! Besides, our noses wouldn’t work in a vacuum.
And yet, there have been several accounts now from Astronauts conducting space walks, that have reported a distinct odour on return to the air-lock. There may be a few reasons for the appearance of a smell in space, and I will try to identify a few of these in answering what does space smell like?
What Are The Accounts Of The Smell Of Space?
There have been a few accounts of space having a smell. Some from astronauts, some from scientists and cosmologists. Suggestions are made based on the composition and nature of the Universe, its contents and its behaviour. Lets take a look at some of these.
Accounts From Astronauts
Many astronauts have described a smell of space. Or rather a distinct odour on their space suits or in the airlock on returning from a space walk. The smell described often varies. In one example, Apollo astronauts returning from the moon described a smell of gunpowder on their spacesuits. In another, astronauts on the ISS report smells of welding fumes or burning metal on their spacesuits.
Other astronaut accounts note smells of steak, burnt almonds, break pads or a smell of ozone. There are others too. But these examples help to illustrate the wide range of scents that astronauts have picked up on their gear after spending time in space.
Smells From Other Missions
As well as accounts from astronauts, different smells have been observed by craft that we have also sent into space. One example came from the Rosetta satellite that we sent to study comet 67P/Churyumov-Gerasimenko. It identified compounds responsible for creating smells of cat urine, rotten eggs and bitter, acrid smells. While the craft could not ‘smell’ these compounds, observing them burning off the comet surface into gas allows us to determine what the smell would be.
By determining the composition of planets and moons, and their atmospheres, we can make a reasonable assumption about how they would smell too.
Where Does The Smell Come From?
There are a few theories about where the smell in space comes from. They are not mutually exclusive so perhaps all are responsible in one way or another. One theory, is that on return to the airlock, astronauts have picked up atomic oxygen on their spacesuits. This then oxidizes on re-pressurization which causes a smell.
Another theory, is that as stars die, they release massive amounts of matter and energy. Some of this matter is released in the form of large clouds of hydrocarbons that carry aromas depending on their chemical makeup. To be more precise, these are known as polycyclic aromatic hydrocarbons (PAHs) and form when a a dying star combusts.
Does The Center Of The Milky Way Have An Odour?
According to researchers, the massive dust cloud at the center of the Milky Way will smell like, believe it or not, rum! But not only that, it will taste of raspberries! As the ability to confirm this through direct first-hand observation is likely lifetimes away, how can they know this?
Well, scientists are able to observe which chemicals are in this cloud right here on Earth. They have identified the chemical compound Ethyl Formate in this cloud, which is the same compound responsible for giving raspberries their taste. Ethyl Formate also smells of rum, and knowing this we can determine what space would smell like in the presence of this cloud.