International Space Station has 'peculiar odor,' astronaut says

European Space Agency astronaut Samantha Cristoforetti takes in the scent of edible plants growing in the eXposed Root On-Orbit Test System (XROOTS) experiment on the International Space Station.
European Space Agency astronaut Samantha Cristoforetti takes in the scent of edible plants growing in the eXposed Root On-Orbit Test System (XROOTS) experiment on the International Space Station. (Image credit: ESA)

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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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: