Humans are stinky creatures. We eat garlic, we fart and we sweat. When you put us together in enclosed spaces, the odors can get almost unbearable (ask anyone who's been to a Comic Con). So how do astronauts living in the confined quarters of the International Space Station deal with odors?
Odors on the ISS come from a variety of sources: equipment "off-gassing," the metabolic processes of astronauts, food, experiments and general body odor. But the space station has equipment prepared for dealing with 216 of these kind of "contaminants."
"In the SM (Service Module), the Micropurification Unit provides a regenerable means to remove both low and high molecular weight contaminants," answers NASA engineer Robert Frost. "In the Lab, the Trace Contaminant Control Subassembly (TCCS) performs a similar function."
Both of these units work in tandem to keep odors at bay inside the ISS and include an activated charcoal bed, a lithium hydroxide sorbent bed, fan and oxidizer. A fan sucks odors into the charcoal, which also contains phosphoric acid to absorb ammonia. Past the fan, recirculated air is oxidized or sent through a bypass line. The air is also heated up and then cooled, while the system removes by-products.
According to retired astronaut Clayton C. Anderson, who spent 159 days at the ISS, the system works in most cases. Astronauts perform regular maintenance on the system to keep the ISS as odor-free as possible.
However, Anderson recounts a story about a fellow astronaut who liked to leave exercise clothes above the Functional Cargo Block of the Russian module of the station, citing that this choice of location did not effectively dry out those clothes.
"I chose to put my nasty shorts/socks/t-shirt onto a handrail in the US segment's Node 1 module," says Anderson. "This handrail was near an A/C vent, meaning fresh, cold air would blow across my sweaty laundry for many hours until I donned them— dry as a bone— the next day."
Anderson points out that his chosen location for sweaty gear also let the ISS' systems suck up the sweat in those clothes and turn it into drinking water for the astronauts.
Anderson also spoke about food odors, which always took the system a little longer to deal with. In fact, on some missions, astronauts banned seafood from the station because its smell lingered for so long.
Space itself, though, also has a smell. Anderson describes it as sort of like the odors associated with welding or burning ozone.
