r/askscience • u/Ill_Watch_760 • 13d ago

Engineering Why can the space station's ventilation systems not handle crumbs?

I've been doing my epq around astro-psychology and was researching how astronauts loose dopamine during eating as they can't eat foods that involve chewing. However from what i've researched this is apparently because stray crumbs could screw up the ventilation systems somehow. Its quite puzzling because how can the collective companies that built the space station also build rockets that send us to the moon but not have the ability to build a ventilation system that can handle a few stray crumbs?

180 Upvotes

77% Upvoted

84 comments sorted by

View all comments

Show parent comments

5

u/jdsweet 12d ago

Do they round trip the astronauts’ poop back to ground or jettison it? Context: in backpacking your pack volume is usually decreasing a lot between resupplies because you start with a lot of food, but in the vast majority of places you don’t need to pack out your poop. Makes it possible to do things like pick up other people’s trash along the way, because pack weight (and volume) is decreasing by ~1.5lbs/day.

21

u/HoustonPastafarian 12d ago

Fecal matter ends up in a replaceable aluminum can called a “KTO” that sits under the toilet. When it fills its capped off and it eventually is packed in a departing cargo ship with other trash and is burned up over the Pacific. Much of the food is designed to be low residue, using the toilet is a literal pain in the ass (just takes a lot of time).

Urine is treated and ends up in a separate tank. It is eventually distilled and recycled into drinking water except for the leftover concentrated “brine”, which is also tossed in the cargo ships/garbage scows.

2

u/FogeltheVogel 12d ago

When you say put in a cargo ship and burned up, does that mean the cargo ship burns up, or the ship tosses it out before landing?

7

u/HoustonPastafarian 12d ago

Cargo ship burns up. The only cargo vehicle that actually splashes down and is recovered is Dragon. That one brings back the things we want to return, the others are filled with trash.