If space is a vacuum, then how can it contain an odor? I read that after spacewalks, astronauts detected an unusual odor after removing their spacesuits. It was compared to the smell of a candle burning. Perhaps this is the smell from the "Big Bang"?

Here's a former astronaut describing the smell: Astronaut Chris Hadfield Debunks Space Myths | WIRED "This one is true! (gunpowder, burnt steak, brimstone)" and What does space smell like? Astronaut Chris Hadfield answers your questions "a little bit like a shooting range, gunpower/cordite, brimstone"

  • $\begingroup$ Something to do with their suits maybe? $\endgroup$
    – Tosic
    Mar 6, 2021 at 19:36
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    $\begingroup$ As Connor says, interesting, but perhaps better on Space Exploration. It needs a good clear source for the claim of an odour. My first thought would be the action of UV on the outer layer of the suit (or the effect of a sweaty human inside the suit) perhaps combined with change in sense of smell when coming out of a suit back to normal air. Nothing to do with "the big bang" or "the smell of space". $\endgroup$
    – James K
    Mar 6, 2021 at 19:41
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    $\begingroup$ It's a great question! I can't up vote for another few hours but I will. I've added some sources verifying the reports that thing that have been in space do have a distinct smell once they are returned to an atmosphere so that they can be smelled. $\endgroup$
    – uhoh
    Mar 6, 2021 at 22:16
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    $\begingroup$ The Big Bang mainly produced hydrogen & helium, which are both odourless gases. It also produced a very tiny amount (around 1 atom per billion) of slightly heavier elements, primarily lithium, and a little radioactive beryllium (which soon decayed to lithium). $\endgroup$
    – PM 2Ring
    Mar 7, 2021 at 17:59
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    $\begingroup$ It can also be something that has to do with airlock and pumps. It would be nice to know the number of chemical species out there and the level of radiation. They might alter somehow the materials of the spacesuit. And our nose can be very sensitive $\endgroup$
    – Alchimista
    Mar 8, 2021 at 10:59

1 Answer 1


If outer space was a perfect vacuum, then there would be no planets or other objects occupying it. How much space are we talking about, and where is this space you refer to? for practical purposes, outer space is defined to as starting at a location past the Kármán line heading outwards from planet Earth. That does not however mean that it is a perfect vacuum. There are still particles, atoms, molecules and other stuff there.

I have also read that Astronauts detect the smell of slight traces of something burnt or burning. This can be caused by a physical effect to do with the way the brain reacts to certain conditions. It may not actually be due to the human olfactory system.


Even though such things may affect Astronauts, NASA or other space agency medical staff may not take it as a long term effect that cannot be corrected or stabilized. And as such still allow Astronauts to space walk with periods of recovery in between. Thus allowing the astronauts to effectively work in outer space, even though they experience such olfactory sensations.

Yeh, I also have seen that video with Astronaut Chris Hadfield. One of the biggest issues with Astronaut habitats in outer space is that they accumulate large amounts of dead skin cells. I mean, huge amounts! So if some of those dead skin cells deposited themselves on the space suits, and radiation outside the craft frazzled the cells, it would smell like burnt steak, when you come back inside the habitat/craft.

  • $\begingroup$ There is something related to this answer here on Earth, too. The smell of (incoming) snow. Curiously, it is also "ozone-like" and electric burnt. Perhaps of physical rather than chemical origin. [I can smell it]. bit.ly/3kXLPut $\endgroup$
    – Alchimista
    Mar 9, 2021 at 10:42
  • $\begingroup$ That's kind of interesting to me, I always thought it smelled more like dust/soil/earthy smell, similar to when you smell the first drops of rain on a hot day. I guess if it comes into contact with charred wood etc...it could also give off a burnt smell. Although were i live it's rare, since I live in the suburbs, and not much charred wood going on there. $\endgroup$
    – Gene Raza
    Mar 10, 2021 at 1:14
  • $\begingroup$ Thanks for the edit! $\endgroup$
    – uhoh
    Mar 10, 2021 at 4:20
  • $\begingroup$ It was not me, another contributor did it. I tried to thank them, however I think they were part of administration and I could not reply. I don't mean to read ungrateful, thanks helpful contributor. $\endgroup$
    – Gene Raza
    Mar 11, 2021 at 8:03

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