Call it the scent of space.
There's a persistent "peculiar odor" on board the International Space Station (ISS) that takes a few days to get used to, according to European astronaut Samantha Cristoforetti.
"When I got here a couple of months ago for my second flight, I could immediately smell a very peculiar odor that brought me back instantly to the memories and sensations of my first flight's odors," Cristoforetti shared on TikTok Monday (July 25). "But within a matter of days, I got used to it, and now I cannot smell it anymore."
Related: Astronaut Samantha Cristoforetti makes history with 1st TikTok from International Space Station
Cristoforetti didn't elaborate on what the ISS smells like, although she did note the capable filters of the space station eliminate most odors. (Cristoforetti finished her first spacewalk July 21, days before the video was posted.)
Other astronauts have commented on space smells like gunpowder or ozone, particularly because atomic oxygen is believed to cling to spacesuits in a vacuum.
Cristoforetti also gave aspiring ISS visitors a rundown of the smelly places to avoid on the space station. In June, the orbiting lab's Expedition 67 crew packed trash high within a Northrop Grumman Cygnus freighter about to depart the ISS for a fiery re-entry. "Of course, that can be smelly," she said of the garbage-filled spacecraft.
Other adverse aromas emanate from the space station's toilet. The toilet is designed to recycle pee into drinkable water; there's always a remainder after this process completes, however. The system evaporates whatever leftover urine remains, and the exhaust can be smelly "in spite of this big filter," Cristoforetti said.
But the European Space Agency astronaut reassured her 600,000 TikTok followers that, aside from these troublesome areas, the ISS is free from fearsome fragrances. "Other than that, the space station smells very pleasant," she said.
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