Outer space is a vacuum, which means it is devoid of air and any other gases or particles that we typically encounter on Earth. As a result, there is no atmosphere in space to carry odors, and therefore, space itself does not have a smell.
However, when astronauts return from spacewalks or missions outside of their spacecraft, they sometimes report experiencing peculiar odors when they remove their helmets or re-enter the pressurized environment of their spacecraft. These odors have been described as a mixture of metallic, burned, or gunpowder-like smells.
The origins of these smells are not entirely clear, but they are believed to be associated with the spacesuits and equipment used during extravehicular activities. Some components of the spacesuits and spacecraft materials, when exposed to the extreme conditions of space (such as vacuum, temperature variations, and radiation), can undergo chemical reactions or outgassing, releasing volatile compounds. These compounds may contribute to the unusual odors that astronauts perceive upon returning to their spacecraft.
It's important to note that these smells are not detected in the vacuum of space itself, but rather when astronauts re-enter their pressurized environment. So, the smell of outer space, as experienced by humans, is not a characteristic of the space environment itself, but rather a result of the interactions between human-made materials and the conditions of space.