https://ntrs.nasa.gov/api/citations/20220005710/downloads/NA...
- To build a centrifuge in space of sufficient size, you need to solve the problem of delivering a large amount of materials to orbit, because it has to be hundreds of meters in diameter at least.
- Such a centrifuge will create a gyroscopic effect, and the station will quickly become very difficult to control.
It's a significant amount of engineering effort, testing, feedback, and iteration to build effective life support systems for manned spaceflight. Long duration spaceflight is orders of magnitude more difficult.
Toilets are systems that can incapacitate or even kill the crew if they malfunction. In a low or microgravity environment aerosolized septic material can get in astronauts' eyes or lungs. It can also seep into electronics or other ship systems causing malfunctions. Even just clean water spraying into the cabin could be dangerous in microgravity.
I knew part of the job for astronauts is being intimate with one's crewmates, but I didn't know it was that intimate.
Namely: astronauts try NOT to as much as they can, and when they do go, it's a mess for both them and their crew mates. They suffer through it because being in space is a worthy achievement.
Apparently it's such a mess that NASA estimates this is why astronauts tend to undereat. Apparently Gemini 7's Frank Borman spent 9 days without going number 2 because of this, and planned to hold it in 2 full weeks (the article doesn't clarify whether he managed). Skylab seems to have done some progress, but we're still in the early eras of space toiletry!