The Smell of Space: A Burnt Hint of the Cosmos
Space is often described as a vast, silent void—a place of stars, silence, and science. But few people realize that space also has a smell. It’s not something you can sniff while floating in a spacesuit, of course. But when astronauts return from a spacewalk and reenter their spacecraft, the lingering scent on their suits tells a strange and fascinating story.
A Scent Like No Other
Astronauts have consistently described the smell of space as something between burnt steak, hot metal, and welding fumes. It’s sharp, metallic, and distinctly charred. NASA astronaut Don Pettit once wrote, “It smells like something I’ve never smelled before, but… it reminds me of a welding torch, right after you’ve struck it.”
So, what causes this otherworldly odor?
Star Dust and Dying Suns
The source of this cosmic aroma lies in chemistry—and more specifically, in high-energy particles interacting with the surface of astronauts’ suits and equipment. When exposed to space, materials are bombarded by atomic oxygen and high-energy ultraviolet radiation. This bombardment can cause the formation of polycyclic aromatic hydrocarbons (PAHs)—complex molecules made up of fused carbon rings.
Interestingly, PAHs are also byproducts of dying stars. They’re scattered across interstellar space and even found in meteorites. These hydrocarbons are thought to play a role in the chemistry of early life, making them even more fascinating. In space, their smell becomes a signature of the universe’s most energetic and ancient processes.
From Training Labs to Earthly Noses
NASA found the space smell so consistently reported that scientists began recreating it. Chemists synthesized the odor for use in astronaut training to prepare them for the unique sensory experience of space. Today, this recreated scent is even used in science outreach—bringing the experience of space just a little closer to Earthbound audiences.
The synthetic version includes compounds like ozone, hot metal, and PAHs—designed to trigger the same burning, metallic aroma astronauts report.
A Cosmic Reminder
The smell of space is more than just a curious detail—it’s a reminder that the universe communicates in more than just light and sound. Our senses can pick up on cosmic clues in surprising ways. This scent, forged in the heat of dying stars and delivered through the cold vacuum of space, offers a uniquely human connection to the cosmos.
It’s one of many subtle ways the universe speaks to us—not just through telescopes or radio waves, but through the scorched scent clinging to a space suit after a walk among the stars.
