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Comment by nicklecompte | Hacker News Reader

One question I have that I didn't see addressed in the article: how does the inner ear work in low gravity? I wonder if this might make astronauts unusually dizzy on the moon because of differences in the vestibular system.

This article seems like a good survey of the general impact low-g has on the inner ear changes, but I've barely skimmed it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8595211/

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There have been studies on the subject, and participants could adapt to rotations as high as 23 RPM. In this test they were more in the 5-10 RPM range (depending on which iteration and how fast the participants were running), so it'd probably be fine after some adjustment.

https://pubmed.ncbi.nlm.nih.gov/14703662/

That is interesting, but my concern is a bit different than that article - I'm worried about what happens when the astronaut stops. After they are done running, they will be at rest in a low-g environment (unlike this experiment), but their inner ear fluid will have most of the momentum it had while they were running - this is the physiological basis of merry-go-round dizziness.

On earth the fluids quickly settle and the dizziness fades. I wonder if maybe it would take considerably longer on the moon. It is probably something they can adjust to, but I was wondering.

I doubt they'd just stop. I imagine in practice this would be more of a parabolic track, and they'd slow to a jog after the peak of their workflow. That would give time for their cochlear fluid to slow down as well.

And even that aside, I'm not sure the lack of gravity would change how quickly cochlear fluid settles. I think that settling is due to resistance from the fluid turbulence of the cochlear canals, not due to gravity.

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