When astronauts return home from space it’s hardly a surprise that people want to ask them all sorts of questions about life on the International Space Station. From living in zero gravity to seeing the Earth from above, the experiences of astronauts are unique ones that very few people get to have. But aside from how space feels and looks, people also seem to want to know how it smells.

The general consensus among astronauts seems to be that space smells a lot like metal.

Russian cosmonaut Sergey Ryazanskiy returned to Earth last week along with NASA astronaut Randy Bresnik and European Space Agency astronaut Paolo Nespoli after a 139-day stay on the ISS. During a press conference following the landing he was asked about the smell of space and said it smells like metal welding, Pravada reported.

Ryazanskiy isn’t the first person to space to describe the smell this way. NASA astronaut Scott Kelly also said it smells like metal during an “Ask Me Anything” on Reddit in October. “Space itself has a very unique smell, kind of like burning metal,” he said. This smell is usually easiest to detect after a hatch has been open for delivery purposes or after astronauts have been outside the station for a spacewalk, he explained.

Astronaut Don Pettit agrees, he called it “sweet smelling welding fumes,” in a post he wrote for NASA as part of the Space Chronicles project. And astronaut Thomas Jones, who completed three spacewalks during his time with NASA, told Space.com something similar. He described the smell as the smell of ozone and said it’s faintly acrid, almost like burnt gunpowder.

Astronauts can’t smell space directly because there’s no oxygen and they have to keep their suits on when doing anything outside of the ISS. What they smell is the leftovers of space almost. Essentially what the astronauts smell is the trace space left on the suits of the astronauts or left on the capsules and cargo they receive on board.