Nobody can say. We have a fair bit of data on medical effects of zero g on adults, but only for short flights, longest so far is fourteen months. We have lots of data on full gravity and hyper gravity on humans.
All we know about lunar gravity by direct experience is the evidence from the lunar astronauts. Obviously they survived it just fine but that was just for a few days.
Generally supposed that lunar gravity is better for you than zero g but not so good as full gravity. But that's based on zero experimental data. It could even be better for us than full g, or worse for us than zero g, for all we know.
It's not a linear thing - there are many parts of the body - circulation, digestion, heart rate, bone loss, all affected in different ways by the levels of gravity - you can't just draw a line from zero to full g and say it must be on that line. Can't say that full g is optimal either - hyper g is bad for us but we have no evidence for low g.
We can't simulate this on the ground, for more than a very short period at a time (in parabolic flight on a plane).
So - "nobody knows".
Also we have no evidence at all about humans born in zero gravity even.
Jellyfish, rats and snails all have some trouble adjusting to full gravity on return to Earth from zero g birth.
Animals Born In Space Have A Hard Time Adjusting To Life On Earth
But there are so many changes in a human body, that pregnant women are not permitted to fly to the ISS. Probably would be the same for lunar colonies for a long time to come.
We could test lunar gravity if we had artificial gravity in LEO. But that's not currently a priority of any of the space agencies.
Humans exposed to zero g adapt back to Earth very quickly on return. It's like gravity is the medicine for zero g. Immediately much healthier within a day or two and gradually recover just about all the things that made them unhealthy in zero g.
But what happens if you return to full g after several years in zero g, or if born there? Again nobody can say. And - nobody can say yet for sure that you could survive many years in zero go or lunar gravity either. If you'd die before you get to 25 then it's a bit of a moot question.
We need experiments in artificial gravity with humans in lunar gravity for long periods of time - or a lunar colony, before we can start to answer this.
See also: Robert Walker's answer to What is the longest time an astronaut can spend in space before it is too hard to re-acclimatize to Earth?
All we know about lunar gravity by direct experience is the evidence from the lunar astronauts. Obviously they survived it just fine but that was just for a few days.
Generally supposed that lunar gravity is better for you than zero g but not so good as full gravity. But that's based on zero experimental data. It could even be better for us than full g, or worse for us than zero g, for all we know.
It's not a linear thing - there are many parts of the body - circulation, digestion, heart rate, bone loss, all affected in different ways by the levels of gravity - you can't just draw a line from zero to full g and say it must be on that line. Can't say that full g is optimal either - hyper g is bad for us but we have no evidence for low g.
We can't simulate this on the ground, for more than a very short period at a time (in parabolic flight on a plane).
So - "nobody knows".
Also we have no evidence at all about humans born in zero gravity even.
Jellyfish, rats and snails all have some trouble adjusting to full gravity on return to Earth from zero g birth.
Animals Born In Space Have A Hard Time Adjusting To Life On Earth
But there are so many changes in a human body, that pregnant women are not permitted to fly to the ISS. Probably would be the same for lunar colonies for a long time to come.
We could test lunar gravity if we had artificial gravity in LEO. But that's not currently a priority of any of the space agencies.
Humans exposed to zero g adapt back to Earth very quickly on return. It's like gravity is the medicine for zero g. Immediately much healthier within a day or two and gradually recover just about all the things that made them unhealthy in zero g.
But what happens if you return to full g after several years in zero g, or if born there? Again nobody can say. And - nobody can say yet for sure that you could survive many years in zero go or lunar gravity either. If you'd die before you get to 25 then it's a bit of a moot question.
We need experiments in artificial gravity with humans in lunar gravity for long periods of time - or a lunar colony, before we can start to answer this.
See also: Robert Walker's answer to What is the longest time an astronaut can spend in space before it is too hard to re-acclimatize to Earth?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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