The ‘disgusting’ reality of what space really smells like according to astronauts

Ever wondered what it actually smells like in space? Well, there's a quick and easy technical answer: true space is a vacuum and you wouldn't be able to smell anything whatsoever up there.

However, most people probably don't mean that when they ask the question - they're probably thinking about what it's like aboard something like the International Space Station (ISS).

Well, it turns out that quite a few astronauts have discussed this question after coming back down to Earth from the ISS.

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Steve Pearce, a biochemist and CEO of Omega Ingredients, was trying to make a bespoke scent for NASA to show people what it smelled like up there, so he apparently went through hours of interview footage and written memoirs to see what different astronauts reported smelling.

According to Live Science, the final combination mixed together "hot metal, burnt meat, burnt cakes, spent gunpowder and welding of metal". Those are some pretty industrial smells, which perhaps shouldn't come as a surprise given that the ISS is basically a metallic series of tubes full of machinery and equipment.

Going into a little more individual detail, American astronaut Don Pettit wrote a blog post for NASA back in 2012 where he described the smell, with some similar notes mentioned: "The best description I can come up with is metallic; a rather pleasant sweet metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch repairing heavy equipment for a small logging outfit. It reminded me of pleasant sweet smelling welding fumes. That is the smell of space."

In fact, Pettit managed to make it all sound quite romantic, although others have had less glowing takes.

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For one thing, there are repeat mentions in interviews of the lurking smell of garbage, which makes sense since all waste has to be carefully collected before it can be disposed of.

Moreover, as pointed out in a Reddit thread on this topic a few months ago, American astronaut Scott Kelly found that his sense of smell was incredibly important up in space - it helped him to work out when there was too much carbon dioxide in the atmosphere.

With complex calibration required on devices to filter this out and keep people breathing healthy air, Kelly reported that after some time in space he could "sense the levels with a high degree of accuracy based only on the symptoms I’ve come to know so well: headaches, congestion, burning eyes, irritability. Perhaps the most dangerous symptom is impairment to cognitive function".

You can see why you'd need to keep on top of this, so it's clear that being able to smell in space is just as practical as it is interesting.