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Uuuh... I thought the gravity on the moon will deform human skeletons, as they are "made" for human gravity, so that makes living anywhere that has different g

Uuuh... I thought the gravity on the moon will deform human skeletons, as they are "made" for human gravity, so that makes living anywhere that has different g impossible. Is that not true?

leni536 11y ago
Then maybe in the long run they would need to build a base that rotates rapidly and simulates a gravity of g at the perimeter by centrifugal force.
- rogeryu 11y ago
  Which will only work in space, not on a planet. That will simply require too much energy, and it will be too complex to build.
- mrfusion 11y ago
  Or more simply just wear weights distributed across your clothes?
  - leni536 11y ago
    Well maybe that works against the bone structure changes. On the other hand gravity (or the lack of it) has other effects too on the human body[1]. One needs to use body forces to compensate the lack of gravity. Contact forces won't help here. [1] https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body#Fluid_redistribution https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_h...
userulluipeste 11y ago
"that makes living anywhere that has different g impossible. Is that not true?" Yes, unfortunately. Currently almost all but the gravity can be taken care of by artificial means. The closest extraterrestrial destination for humans is now the planet Venus.
nkoren 11y ago
No, it's not "true". It's "unknown". To date, there have been no studies of how human (or any other) physiology holds up in low-gravity environments. There have been a lot of studies showing that zero gravity[1] is reasonably unhealthy, but there is a lot of room between earth gravity and zero gravity. At what point does lower gravity become unhealthy? 90% earth gravity? 10% earth gravity? 1% earth gravity? Nobody knows; no research has been done. We need to get some experience with it. It doesn't seem reasonable to speculate that anything less than 100% earth gravity will be unhealthy. Gravity itself can be a significant and damaging stress on the body; a bit less gravity may actually improve health, not hurt it. For this reason, it's also not reasonable to speculate a linear slope between "healthy at 100% earth gravity" and "unhealthy at zero gravity". The slope is very likely non-linear, but nobody knows what it looks like. Some space medicine people I've talked to speculate that lower gravity is probably harmless, up to the point where fluids stop flowing downhill. Your body relies on gravity to redistribute fluids throughout your extremities; in zero-gravity, this no longer happens, and a lot of weird things start happening as a result. If this is the case, then lunar gravity (1/6th earth gravity) should be just fine to live in. But, again, we don't know, and all the zero-gravity experiments in the world won't tell us. Until we get some proper low-gravity experience, it's a big question-mark. 1: Technically, "micro-" gravity, since "zero-" doesn't exist in reality. But it's very, very, very micro -- like, 1/1000th earth gravity or less.
joshuapants 11y ago
Well, we have lots of data on zero gravity from various astronauts in space who have been up for long periods of time. In zero g, muscles atrophy and bones get less dense. The longest moon mission was 12 days, not really enough to know what moon gravity can do to a human over time. I think there is some hope that low-but-not-zero gravity will have less pronounced effects in the long run.

Uuuh... I thought the gravity on the moon will deform human skeletons, as they are "made" for human gravity, so that makes living anywhere that has different g impossible. Is that not true?

leni536 11y ago

Then maybe in the long run they would need to build a base that rotates rapidly and simulates a gravity of g at the perimeter by centrifugal force.

rogeryu 11y ago
Which will only work in space, not on a planet. That will simply require too much energy, and it will be too complex to build.
mrfusion 11y ago
Or more simply just wear weights distributed across your clothes?
- leni536 11y ago
  Well maybe that works against the bone structure changes. On the other hand gravity (or the lack of it) has other effects too on the human body[1]. One needs to use body forces to compensate the lack of gravity. Contact forces won't help here. [1] https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body#Fluid_redistribution https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_h...

userulluipeste 11y ago

"that makes living anywhere that has different g impossible. Is that not true?" Yes, unfortunately. Currently almost all but the gravity can be taken care of by artificial means. The closest extraterrestrial destination for humans is now the planet Venus.

nkoren 11y ago

No, it's not "true". It's "unknown". To date, there have been no studies of how human (or any other) physiology holds up in low-gravity environments. There have been a lot of studies showing that zero gravity[1] is reasonably unhealthy, but there is a lot of room between earth gravity and zero gravity. At what point does lower gravity become unhealthy? 90% earth gravity? 10% earth gravity? 1% earth gravity? Nobody knows; no research has been done. We need to get some experience with it. It doesn't seem reasonable to speculate that anything less than 100% earth gravity will be unhealthy. Gravity itself can be a significant and damaging stress on the body; a bit less gravity may actually improve health, not hurt it. For this reason, it's also not reasonable to speculate a linear slope between "healthy at 100% earth gravity" and "unhealthy at zero gravity". The slope is very likely non-linear, but nobody knows what it looks like. Some space medicine people I've talked to speculate that lower gravity is probably harmless, up to the point where fluids stop flowing downhill. Your body relies on gravity to redistribute fluids throughout your extremities; in zero-gravity, this no longer happens, and a lot of weird things start happening as a result. If this is the case, then lunar gravity (1/6th earth gravity) should be just fine to live in. But, again, we don't know, and all the zero-gravity experiments in the world won't tell us. Until we get some proper low-gravity experience, it's a big question-mark. 1: Technically, "micro-" gravity, since "zero-" doesn't exist in reality. But it's very, very, very micro -- like, 1/1000th earth gravity or less.

joshuapants 11y ago

Well, we have lots of data on zero gravity from various astronauts in space who have been up for long periods of time. In zero g, muscles atrophy and bones get less dense. The longest moon mission was 12 days, not really enough to know what moon gravity can do to a human over time. I think there is some hope that low-but-not-zero gravity will have less pronounced effects in the long run.