How do astronauts poop in space?

Without gravity, nothing falls: a current of air has to be created to carry waste away. The station's toilet is a sealed tank topped with a small seat with an opening much narrower than an Earth toilet bowl; a fan sucks air through this opening and draws solid waste into a disposable bag housed in a container. Urine, meanwhile, goes into a funnel connected by a flexible hose, with each crew member having their own personal attachment. Thigh straps and footholds keep the user in place.

The trade-off for this narrow opening is that aim matters. Candidates train on the ground on a mock-up fitted with a camera placed inside the bowl, which shows the exact position of the body on a screen; the exercise, often mocked, prevents unpleasant incidents that would be hard to clean up in weightlessness. The session itself takes longer than on Earth: securing the straps, checking the airflow, cleaning surfaces with disinfectant wipes, replacing the bag and the personal attachment.

Full containers are stored and then loaded onto a cargo spacecraft that burns up in the atmosphere during reentry: solid waste is not recycled. Urine, on the other hand, is valuable: treated on board, it joins the station's drinking water system along with condensation from cabin air. That leaves spacewalks, launches and reentries, during which no one can leave their suit: crew members then wear an absorbent garment, a solution inherited from the early days of spaceflight and still in use today.