Astronauts Feel a Distinctive Smell in Space, Where Does It Come From?

SPACE — When astronauts return from space travel, they often describe an unexpected smell similar to burnt steak and spent gunpowder. But why does outer space smell like burnt objects, and where does the smell come from?

To be clear, space is an almost perfect vacuum. While in space, astronauts protect themselves inside spacecraft, space suits, and space stations. Because direct exposure will of course kill them.

Therefore, no one has ever smelled space directly. However, after returning from a journey on the final frontier, astronauts often smell a unique odor when taking off their helmets. “Outer space definitely smells different than anything else,” said NASA astronaut Dominic ‘Tony’ Antonelli after a spacewalk in 2009.

Steve Pearce, biochemist and CEO of Omega Ingredients, was commissioned by NASA to create a signature space scent. He also interviewed many astronauts. According to him, overall, astronauts often compare the smell of space to hot metal, burning flesh, burning cakes, spent gunpowder and metal welding.

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Meanwhile, former NASA astronaut Thomas Jones compared the smell to ozone. Another NASA astronaut, Don Pettit, described the smell of outer space at length, which is essentially a metallic smell

“The best description I can give is metallic, a nice sweet metallic sensation. It reminds me of college summers, where I worked long hours with an arc welding torch repairing heavy equipment for a logging company. It reminds me of welding fumes that smells sweet and pleasant. That’s the smell of space,” said Don Pettit.

Where does this scent come from? Although space is mostly empty, it is not a perfect vacuum. “We’re not actually talking about a volume that has no particles,” said Miranda Nelson, a spaceflight controller in Mission Control at NASA’s Johnson Space Center.

There are a number of possible explanations for the smell. One of them has to do with oxygen circulating around the International Space Station (ISS).

Ultraviolet light from the sun can break down oxygen molecules (O2), which are made from two oxygen atoms, into single oxygen atoms. Oxygen atoms can stick to spacesuits, airlock walls, and other objects exposed to outer space. “That triggers chemical reactions that may cause the odor, such as the formation of ozone,” Nelson said.

Also Read: Why is the Universe Dark?

Nelson continued, another more favorable theory is that the smell is related to the explosion of dying stars. This explosion produces odorous molecules known as polycyclic aromatic hydrocarbons? On earth, the molecule is often found in coal, food, oil and other materials. However, Nelson stressed, official study data for both ideas is still lacking.

To help make astronaut training more realistic, NASA commissioned Pearce in 2008 to create a scent that mimics the smell that astronauts describe. The goal is to eliminate shocks that astronauts may experience in orbit.

Pearce had never been to space or smelled anyone’s spacesuit when designing the fragrance. “I recreated the astronauts’ descriptions, using my knowledge and experience of available safe aroma ingredients that, when combined, could give rise to similar perceptions,” he said.