Astronauts returning from spacewalks frequently report a distinct odor clinging to their spacesuits and equipment.
Astronauts who have gone on spacewalks consistently speak of space's extraordinarily peculiar odor.
They can't smell it while they're actually bobbing in it, because the interiors of their space suits just smell plastic-y. But upon stepping back into the space station and removing their helmets, they get a strong, distinctive whiff of the final frontier. The odor clings to their suit, helmet, gloves and tools.
Fugitives from the near-vacuum — probably atomic oxygen, among other things — the clinging particles have the acrid aroma of seared steak, hot metal and welding fumes. Steven Pearce, a chemist hired by NASA to recreate the space odor on Earth for astronaut training purposes, said the metallic aspect of the scent may come from high-energy vibrations of ions.
"It's like something I haven't ever smelled before, but I'll never forget it," NASA astronaut Kevin Ford said from orbit in 2009. [Space Sights and Smells Surprise Rookie Astronauts]
But astronauts don't dislike the sharp smell of space, necessarily. After a 2003 mission, astronaut Don Pettit described it this way on a NASA blog:
"It is hard to describe this smell; it is definitely not the olfactory equivalent to describing the palette sensations of some new food as 'tastes like chicken.' The best description I can come up with is metallic; a rather pleasant sweet metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch repairing heavy equipment for a small logging outfit. It reminded me of pleasant sweet smelling welding fumes. That is the smell of space."