Friends, Many years ago—in a book about building space stations—I read that humans can thrive and maintain enough bone density and muscle to successfully reacclimatize to live at 20% Earth's Gravity.

I don't remember the name of the book and since we can't simulate 20% Gravity here on Earth, I'm curious how the figure was arrived at.

At any rate, picture a multi-tiered structure with artificial gravity ranging from 60% with levels at 50%, 40%, 30% & 20%. the main character spends time doing manual labor on each of the levels regularly.

However, his house has 60% Gravity—but his bedroom is set to 10% to maximize rest. He also has a weight room at 100% Gravity where he spends 2 or 3 hours lifting three time weekly AND he has a walking track where the gravity is 130% Earth's Gravity.

Should he show any bad effects—or benefits—from spending about two-thirds if his time in a low-gravity environment?

Saxon Violence

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    $\begingroup$ We can easily simulate 20% gravity on Earth. In a pool. (Good old Archimedes!) That's how NASA trains astronauts for work in microgravity. The bit about being able to reacclimate is physiological speculation. $\endgroup$
    – AlexP
    Aug 26, 2017 at 23:32
  • $\begingroup$ It's worth noting that low-G is not generally associated with improved rest, as well. Many astronauts have noted a decrease in "good" sleep on missions. $\endgroup$
    – jdunlop
    Aug 27, 2017 at 3:25
  • $\begingroup$ Imagine doing your business in the toilet at 0g... $\endgroup$
    – user6760
    Aug 28, 2017 at 11:07
  • $\begingroup$ There's not much research into the subject. We should get scientists to look into it, especially when space travel becomes easier. $\endgroup$ Apr 8, 2021 at 20:39

1 Answer 1


Many years ago—in a book about building space stations—I read that [...]

I am afraid that since then studies have gone further, showing that human bodies suffer in low gravity, showing muscle tone loss, bone weaking and immunodepression.

Astronauts nowaday struggle to contain the damage by constantly exercising, but still getting back to normal gravity requires some days in which and the whole process it is not even clearly understood by medical scientists.

Scientists aren't yet sure how gravity "signals" the body to keep bones and muscles strong. "We know that, somehow, gravity is converted from a mechanical signal to a chemical signal -- and we know a lot about these chemical signals" [source]

Long story short, we have no experience, yet. Astronauts in the Space Station are guinea pigs used to answer this question, and tell if we can really leave this blue bubble and venture into space.

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    $\begingroup$ Astronauts on the ISS live in microgravity, close 0 g. It may weel be that 0.2 g is enough to avoid serious physiological effects. It is still speculation, though. $\endgroup$
    – AlexP
    Aug 27, 2017 at 7:17

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