A commonly trotted out argument for continued investment in manned space flight is technological spillover: that all the money we give to NASA generates positive benefits in other sectors of the economy. I'm not so sure space toilets are generating that spillover. This seems like a uniquely expensive humans-in-space engineering problem. I echo the sentiments of Why Not Mars (https://idlewords.com/2023/1/why_not_mars.htm):
> The web of Rube Goldberg devices that recycles floating animal waste on the space station has already cost twice its weight in gold and there is little appetite for it here on Earth, where plants do a better job for free. [...] I would compare keeping primates alive in spacecraft to trying to build a jet engine out of raisins. Both are colossal engineering problems, possibly the hardest ever attempted, but it does not follow that they are problems worth solving. [...] Humanity does not need a billion dollar shit dehydrator that can work for three years in zero gravity, but a Mars mission can’t leave Earth without it.
Why are we doing human spaceflight again?