How does space smell?

“How does space smell?”, Lana Yolovich asks us on our Facebook page. This is the question of our week. Thank you all for your participation.

“We’re talking about extra-cooked steaks, hot metal, casting smoke and barbecue.”

“I like this question, but it’s the hardest. Because, yes, space smells … but how does it smell?”In his book, Tim Pick, a British astronaut who spent six months on the International Space Station (ISS) in 2015-2016, expressed surprise. Is there Wi-Fi in space? (Published in 2019). The astronaut said that every time he opened the ISS airlock, he got a strong and special smell. “This mysterious smell gives rise to a lively and amusing debate among astronauts. We talk about overcooked steaks, hot metals, casting smoke and barbecue, among others (…) I find this smell rather pleasant, it’s a bit like a British summer.” Reminiscent of barbecue, with sausage grated on charcoal grills … ”

Could this smell be from the suit itself, some of the ingredients of which become “dagas” after exposure to vacuum and extreme temperatures? Tim Pick doesn’t mind and has another theory. “I’ve got the same smell two or three times in the empty Japanese airplane after repressorization. In my opinion, the smell of space is like static electricity. For example, sometimes the static discharge that comes from taking off a shirt or sweater. According to him, the odor that goes with static electricity is probably that of ozone (O3). The latter can occur naturally when high-energy UV rays (from the sun, lightning, or static electricity) hit the oxygen molecules (O2) and split them into two isolated oxygen atoms. An emitted oxygen atom then combines with another oxygen molecule (O2) to form O3. Ozone is present in the lower part of the stratosphere, about 20 or 30 km above the Earth, but not around the ISS (about 350 km altitude), so why would astronauts feel it while doing a spacewalk? This is because the tiny atmosphere present at this altitude is largely composed of atomic oxygen. “It is possible that nuclear oxygen will be introduced into the air locks when it is open to space, and after suppression will react with the oxygen molecules in the space station, forming ozone.”Tim Pick believes.

The smell of dying stars?

A second theory, quite poetic, blames the smell of space left behind by dead stars. In fact, there is a lot of burning in the universe. Formed mainly by hydrogen and helium gas, the stars are driven by a nuclear fusion reaction that can last for billions of years. Towards the end of its life, once its combustible hydrogen is depleted, the star collapses on its own in a fierce supernova explosion during which heavy elements such as oxygen, carbon, gold and uranium are formed. This glossy combustion emits an odorous compound called polycyclic aromatic hydrocarbons (PAHs). According to some NASA scientists, these PAHs float forever and are found throughout the universe, including ISS and … Earth. “So as soon as we sniff into the air lock, will we smell the remnants of some of the early stars? Who knows?”Asks Tim Pick.

A perfume “to feel the space”

Even those who don’t have a chance to go to space can smell it … for a perfume. The concept was born in 2008 when Steve Pierce, a chemist at NASA’s Omega Ingredients Company, was asked to reproduce this special odor that astronauts feel when they open the ISS airlock. The project was planned to introduce the scent to astronauts during training on Earth. But since 2020, it has also been marketed as “Eau de Space” (it sells for less than 50 euros). For fans of this type of product, be aware that NASA and Omedia Ingredients have created a perfume with “Moon Scent” called “Eau de Luna”. At the same price as the smell of space.

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