What Does Space Really Smell Like? (And Why You Can't Smell It Directly!)

The bizarre "smell of space" is believed to be a byproduct of atomic oxygen, which is abundant in the low Earth orbit environment. When spacecraft and suits are exposed to this highly reactive atomic oxygen, it can cause oxidation of materials. Upon returning to the pressurized cabin and re-exposure to molecular oxygen, these oxidized materials react, releasing volatile compounds that produce the unique odor. Descriptions from astronauts vary, ranging from "hot metal," "fried steak," and "raspberries" to "ozone" or even "gunpowder," hinting at complex chemical processes at play.