Let's talk space toilets • Hacker News Board

Re: Let's talk space toilets

#11

Post by TylerE » Tue, Apr 14, 2026, 6:38 PM UTC

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

You wouldn’t want to use a regular toilet even if you could, given how tight water margins are. Urine you can reclaim, feces not so much.

Re: Let's talk space toilets

#12

Post by yshamrei » Tue, Apr 14, 2026, 6:44 PM UTC

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

There are two issues:

- 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.

Re: Let's talk space toilets

#13

Post by amluto » Tue, Apr 14, 2026, 6:51 PM UTC

TylerE wrote: post #11

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

You wouldn’t want to use a regular toilet even if you could, given how tight water margins are. Urine you can reclaim, feces not so much.

Vacuum flush toilets are common on airplanes, trains, and ships and use a lot less water than a conventional toilet.

Re: Let's talk space toilets

#14

Post by cubefox » Tue, Apr 14, 2026, 7:00 PM UTC

detourdog wrote: post #5

I was surprised there were no pictures of the actual toilets. Would love more but found this. https://en.wikipedia.org/wiki/Space_toilet

This goes into a bit more mechanical detail than the Substack post (which only gestures at "air suction"). I'm still not sure whether there are different urine hose adapters for men and women or not.

Re: Let's talk space toilets

#15

Post by giantrobot » Tue, Apr 14, 2026, 7:01 PM UTC

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

Even with centrifugal "gravity" the toilets need to be designed for the worst case scenario (no "gravity"). Even if you could use a "regular" toilet the system needs to sequester and process the septic waste. That precludes even using the likes of an airplane toilet.

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.

Re: Let's talk space toilets

#16

Post by idlewords » Tue, Apr 14, 2026, 7:08 PM UTC

cubefox wrote: post #14

detourdog wrote: post #5

I was surprised there were no pictures of the actual toilets. Would love more but found this. https://en.wikipedia.org/wiki/Space_toilet

This goes into a bit more mechanical detail than the Substack post (which only gestures at "air suction"). I'm still not sure whether there are different urine hose adapters for men and women or not.

The hose is the same but there are different funnel attachments (the part looks kind of like the cup from a jock strap, and is longer and narrower for women)

Re: Let's talk space toilets

#17

Post by bdamm » Tue, Apr 14, 2026, 7:13 PM UTC

The roasting process is both hypermodern and curiously antique. Burning dung is a tradition passed down across the millenia!

Re: Let's talk space toilets

#18

Post by ethan_smith » Tue, Apr 14, 2026, 7:13 PM UTC

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

The centrifugal gravity approach requires a massive structure - you need something like 200+ meter radius to keep rotation rates low enough that Coriolis effects don't make people nauseous (which would create a whole different toilet problem). Building a better space toilet is orders of magnitude cheaper and lighter than spinning up a habitat.

Re: Let's talk space toilets

#19

Post by chinabot » Tue, Apr 14, 2026, 7:35 PM UTC

ooterness wrote: post #10

Is it simpler to build a better space toilet, or to build a ship with centrifugal gravity and use a regular toilet?

If people are going to live in space for any period of time then they are going to need gravity so long term, yes.

Re: Let's talk space toilets

#20

Post by assimpleaspossi » Tue, Apr 14, 2026, 7:37 PM UTC

I've always wondered about regular toilets and now this. Someone has to test it. I'm sure they have equivalent items to run through them but, eventually, you have to try the real thing so whose job is it to do that and how do they do that?