Yes, there are many potential medical issues. It's not proved either way but plenty of reason for great caution.
Our body is balanced to work in full gravity - and never in evolution has any creature evolved on Earth under less than full gravity.
This shows we can't just expect the body to function properly in low g or zero g. It's often forgotten now, but at the start of the space program, nobody knew for sure if humans could survive even an hour in zero g. That's why the US and Russia did a series of experiments with monkeys first.
Same is true for low g. Our body is far too complex to simulate. You have to test and experiment and the experiment has never been done for low g. It might be better for health even than full g, reasoning behind idea of "retirement homes on the Moon". Or might be anywhere between zero and full g in its harmful effects. Might even be worse than zero g - unlikely - but not sure that can be ruled out.
Some things that are physically different in zero g and also will be in less than full g:
The human body changes in many ways in zero g. Astronauts continually lose bone mass, and their body has immediate changes hours after they first enter zero g. They have to do a rigorous exercise regime to keep normal levels of fitness - and only a handful of cosmonauts, all Russian, have spent over a year in space, some of them had serious health issues in orbit.
Few people realize quite how much the human body changes in zero g. But look up the medical issue and there is extensive data on it now.
Here are some of the issues of zero g:
Most of those problems clear up a few months after return to Earth, and some clear up almost immediately on exposure to full gravity. Bone loss takes longer though, it can be several years before your bones return to their normal strength after a long duration spaceflight.
It's not known if humans can live long term in zero g. The record is 437 days but the Russian cosmonaut who survived that long in space might just be extremely lucky.
It's considered probably unsafe to carry a fetus or give birth in zero g, for these reasons, though it is unethical to do the experiment to find out for sure.
Pregnant women are not permitted to fly to the ISS for this reason.
William Rowe has also turned up possible evidence of a risk of sudden heart failure after moderate exercise such as a space walk, due partly to adapatation to zero g conditions. Researches in this area are somewhat restricted because NASA has a policy that they don't release individual medical data about their astronauts until after they die, and until then only release aggregate data.
Nobody knows whether or not the same issues apply to low g such as lunar or Martian levels of gravity. With only two data points, zero g, and full g, we can't interpolate to find out what happens with low g.
Optimists say that the human body at Martian and Lunar levels of gravity will adjust to keep the body healthy at these levels. But there is absolutely no evidence either way on this.
We know that zero g is very unhealthy long term unless you do a vigorous exercise regime, and do not know if it is possible to stay healthy with exercise long term in zero g. Indeed don't know if it is possible to stay healthy long enough for the Inspiration Mars fly by. It could be that all humans would die after two years exposure to zero g, as our experiments haven't been done for long enough to prove this either way.
In a recent space show a doctor William Rowe, a specialist in human physiology in space. gave as his opinion that because of all these complications, most people would die within two years of exposure to zero g.
Low gravity could be intermediate - e.g. that you can live for 15 years say, in low g - or it could be better than you - longer lived and more healthy in low g at some g levels even than at full g (e.g. idea some have of homes for the ill and elderly on the Moon if that was true) - or even, that some levels of low g are worse for you than zero g.
The human body hasn't evolved to survive in low g. We can't simulate low g. on the Earth. Nobody has ever done an experiments with humans in low g in space, or indeed with any animal except a couple of experiments with rats done by the Russians.
Why subject yourself to all the issues of low g - at the very least, really likely that your children would not be able to return to Earth - and all the other issues of Mars such as radiation levels.
Agreed not impossible to survive on Mars - with meters of regolith over the places where you spend most of your time - still - more hazardous than the Earth immediately after a global nuclear war.
Also near vacuum for "atmosphere", almost no ice on the planet compared to Earth - no disaster on Earth that we know of, likely to happen in next few hundred million years, could make it a worse place to live than Mars. Except in artificial habitats, that is.
For more about this:
As for terraforming Mars - that's a thousand year long project according to the most optimistic - and a hundred thousand year long project to those who are more cautious about it - both highly technological and with much to go wrong, when we have difficulty keeping a technological project going long term for a few decades and have no ground truth at all about how easy or hard it is.
See
This is often forgotten, or at least almost never mentioned in the news articles about colonizing Mars - but humans carry trillions of microbes with them, in thousands of species, and we would die if you try to sterilize us of them, and leak them into our environment all the time.
This would hugely confuse studies of pristine Mars, with experiments planned that can detect a single amino acid in a sample, or a single DNA molecule or other biological marker.
It is just not feasible to land a human mission on Mars without a greatly increased risk of contaminating it, with Earth life, especially since there would be a significant risk of a hard landing.
How could a human spaceship contain all its microbes after a crash on Mars that destroys the spacecraft, kills all the crew and leaves debris scattered over the surface? And how could such an innovative and difficult mission as a landing on Mars be so safe you are confident that won't happen?
Also there's evidence that Mars may well be habitable for life. If so it could spread, through exponential growth, over the entire surface within decades, like the rabbits and other placental mammals spreading over Australia.
That would be the end of any chance to look at Mars is like in its current pristine state, and could delay our chances for decent understanding of early Mars by decades or centuries.
It could also cause big problems for future colonists on Mars if we do ever decide to colonize or terraform it. You are talking about seeding a planet with microbes from a human habitat, and letting them evolve in a radiative fashion and see what they turn into in conditions of near vacuum, and high levels of radiation, after all. Seems not at all impossible that the results could be microorganisms hazardous to humans and our habitats, and hard or nearly impossible to sterilize.
Then many ideas for terraforming Mars involve a careful process of introducing microbes step by step, with only plants to start with - and most of all, canobacteria for instance to generate oxygen. Animals and aerobes that eat the oxygen would only be introduced at a far later date. But colonists would introduce those right away, and it would be impossible to reverse this if they start to spread over the surface of Mars.
And - there are the warm seasonal flows,now known even in the equatorial region, probably involving liquid water, and the DLR experiments that suggest that lichens and cyanobacteria can survive on the surface of Mars possibly almost anywhere using night time humidity (same as causes the frosts on Mars).
At the very least this needs far more research and detailed understanding of conditions on Mars and enough knowledge to exactly reproduce conditions there, not just guesses.
But - there seems actually no benefit as far as exploration, for humans on the surface, just major issues.
A lot is made of the flexibility of humans on the surface. That's true of a planet surface with an atmosphere - even if you can't breath it. But spacesuits are clumsy, as you see with the ISS when astronauts find it tough to do even simple things because of the stiffness of the spacesuit gloves especially (because of the vacuum outside of the glove) - and humans can only get around on the surface for any distance if they carry many tons of equipment for life support with them as well in their rovers.
Spacesuits of course will be improved but so also will telerobots, easier and easier to control.
Machines can be light and agile, even light enough to fly - and can be controlled from orbit, saving humans the dangerous descent to the surface, and able to go to places humans could never go.
This idea of controlling them from orbit - can reduce the light speed delay to almost nothing would deal with just about all the issues that you get driving our rovers around on the surface of Mars from Earth and doing experiments there from Earth. There's no need to go to the surface for that. The HERRO study particularly found that it would get far more science done, for less cost, than a surface mission.
See
If you are going to live in artificial habitats, there's also far more space available to colonize as spinning habitats in space. That may surprise you, but work out the figures,there's far more potential in free space than on planetary surfaces, if you work out the amount of material available for shielding a calculation that goes back to the 1970s.
And - this is for large spacious habitats - okay you are surrounded by tons per square meter just as for Mars of radiation shielding - but - this is in free space so you can build it up into a big spacious habitat, kilometers across. Very hard to do that on Mars with same levels of shielding. And can control the environment, warmth of the tropics if you like, main problem in space is radiating the heat away not keeping warm.
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THEORETICAL PHYSICAL REASONS THAT CHANGE THINGS
Our body is balanced to work in full gravity - and never in evolution has any creature evolved on Earth under less than full gravity.
This shows we can't just expect the body to function properly in low g or zero g. It's often forgotten now, but at the start of the space program, nobody knew for sure if humans could survive even an hour in zero g. That's why the US and Russia did a series of experiments with monkeys first.
Same is true for low g. Our body is far too complex to simulate. You have to test and experiment and the experiment has never been done for low g. It might be better for health even than full g, reasoning behind idea of "retirement homes on the Moon". Or might be anywhere between zero and full g in its harmful effects. Might even be worse than zero g - unlikely - but not sure that can be ruled out.
Some things that are physically different in zero g and also will be in less than full g:
- Blood would normally pool in our legs - and our body is adjusted to counteract gravity to prevent that happening. Take away gravity and the blood pressure increases in the upper part of the body - which puts our body out of balance. It won't automatically compensate for this because all its mechanisms evolved in full gravity
- Our bones and muscles are used to constant 1 g downwards force. It's just wishful thinking to say that when you lose bone matter in low g, that you lose just enough to adapt to low g. No animal has ever, in evolutionary past, been exposed to less than full g. So why should it have a finely tuned adaptation to create just the right amount of bone loss for the strength of bone needed to avoid fractures etc in low g?
- On Earth, our body lose heat constantly through convection - warm drafts rising from our body. In space those same warm drafts don't go anywhere but just hug our body. So it overheats - so you sweat a lot - and many of the issues are a result of that overheating.
- Even microbes behave differently in zero g if in films or communities (this was a surprising discovery), so also, on a cellular level, our body is not responding in exactly the same way, same would apply in low g.
OBSERVED CHANGES
The human body changes in many ways in zero g. Astronauts continually lose bone mass, and their body has immediate changes hours after they first enter zero g. They have to do a rigorous exercise regime to keep normal levels of fitness - and only a handful of cosmonauts, all Russian, have spent over a year in space, some of them had serious health issues in orbit.
Few people realize quite how much the human body changes in zero g. But look up the medical issue and there is extensive data on it now.
Here are some of the issues of zero g:
- bone loss, lose 1 or 2% of your bone mass every month in load bearing parts of your skeleton such as feet. (Your skull and other parts that don't bear weight are unaffected by this).
- eye problems (many astronauts have short term issues after their flight, and there's been one case of irreversible damage to sight as a result of zero g),
- thinner blood (reduction in blood cell count can be as much as 15% after two weeks in space),
- more blood in the upper body,
- increased resting heart rate,
- greatly increased levels of adrenaline,
- reduced digestion leading to malnutrtion
- issues in liver and kidney function,
- changes in function of immune system, r
- reduced thirst leading to dehydration,
- increased core temperatures,
- can only get rid of heat by sweating, not by convection so increased sweating
- The sweating leads to magnesium deficiency,
- increased iron,
- can't take most medicines orally, only subcutaneously because of the stomach, liver and kidney issues,
Most of those problems clear up a few months after return to Earth, and some clear up almost immediately on exposure to full gravity. Bone loss takes longer though, it can be several years before your bones return to their normal strength after a long duration spaceflight.
It's not known if humans can live long term in zero g. The record is 437 days but the Russian cosmonaut who survived that long in space might just be extremely lucky.
It's considered probably unsafe to carry a fetus or give birth in zero g, for these reasons, though it is unethical to do the experiment to find out for sure.
Pregnant women are not permitted to fly to the ISS for this reason.
William Rowe has also turned up possible evidence of a risk of sudden heart failure after moderate exercise such as a space walk, due partly to adapatation to zero g conditions. Researches in this area are somewhat restricted because NASA has a policy that they don't release individual medical data about their astronauts until after they die, and until then only release aggregate data.
Nobody knows whether or not the same issues apply to low g such as lunar or Martian levels of gravity. With only two data points, zero g, and full g, we can't interpolate to find out what happens with low g.
Optimists say that the human body at Martian and Lunar levels of gravity will adjust to keep the body healthy at these levels. But there is absolutely no evidence either way on this.
We know that zero g is very unhealthy long term unless you do a vigorous exercise regime, and do not know if it is possible to stay healthy with exercise long term in zero g. Indeed don't know if it is possible to stay healthy long enough for the Inspiration Mars fly by. It could be that all humans would die after two years exposure to zero g, as our experiments haven't been done for long enough to prove this either way.
In a recent space show a doctor William Rowe, a specialist in human physiology in space. gave as his opinion that because of all these complications, most people would die within two years of exposure to zero g.
Low gravity could be intermediate - e.g. that you can live for 15 years say, in low g - or it could be better than you - longer lived and more healthy in low g at some g levels even than at full g (e.g. idea some have of homes for the ill and elderly on the Moon if that was true) - or even, that some levels of low g are worse for you than zero g.
The human body hasn't evolved to survive in low g. We can't simulate low g. on the Earth. Nobody has ever done an experiments with humans in low g in space, or indeed with any animal except a couple of experiments with rats done by the Russians.
WHY SUBJECT YOURSELF TO ALL THAT
Why subject yourself to all the issues of low g - at the very least, really likely that your children would not be able to return to Earth - and all the other issues of Mars such as radiation levels.
Agreed not impossible to survive on Mars - with meters of regolith over the places where you spend most of your time - still - more hazardous than the Earth immediately after a global nuclear war.
Also near vacuum for "atmosphere", almost no ice on the planet compared to Earth - no disaster on Earth that we know of, likely to happen in next few hundred million years, could make it a worse place to live than Mars. Except in artificial habitats, that is.
Artists' impressions of giant impact#s on the Earth. Some of these might cause a firestorm over the entire Earth, which burns up just about everything and makes most species extinct over the entire Earth. This is about the only likely thing that could make Earth momentarily uninhabitable by humans throughout its surface - and that just for a few hours during the firestorm. Anyone who survived, underground or beneath the sea, would find the surface of the Earth is still, by far, the most habitable place in the solar system and best place to "re-terraform".
For more about this:
- No Escape From Problems in Space Colonies - Earth is Des Res - Even After Nuclear War or Asteroid Impact
- Let's Plan For Exploration and Discovery of Space with no End Date - NOT Escape from Earth - Opinion Piece
- Why Elon Musk's Colony on Mars in 2020s is Unfeasible - What Could We Do - Really?
- Why Mars is NOT a Great Place to Live - Amazing to Explore From Orbit - with RC Rovers, and Nature Inspired Avatars
As for terraforming Mars - that's a thousand year long project according to the most optimistic - and a hundred thousand year long project to those who are more cautious about it - both highly technological and with much to go wrong, when we have difficulty keeping a technological project going long term for a few decades and have no ground truth at all about how easy or hard it is.
See
- To Terraform Mars with Present Technology - Far into Realms of Magical Thinking - Opinion Piece
- Trouble With Terraforming Mars
- Could Microbes Transferred On Spacecraft Harm Mars Or Earth - Zubrin's Argument Revisited
PLANETARY PROTECTION AND VALUE OF PRISTINE MARS
This is often forgotten, or at least almost never mentioned in the news articles about colonizing Mars - but humans carry trillions of microbes with them, in thousands of species, and we would die if you try to sterilize us of them, and leak them into our environment all the time.
This would hugely confuse studies of pristine Mars, with experiments planned that can detect a single amino acid in a sample, or a single DNA molecule or other biological marker.
It is just not feasible to land a human mission on Mars without a greatly increased risk of contaminating it, with Earth life, especially since there would be a significant risk of a hard landing.
How could a human spaceship contain all its microbes after a crash on Mars that destroys the spacecraft, kills all the crew and leaves debris scattered over the surface? And how could such an innovative and difficult mission as a landing on Mars be so safe you are confident that won't happen?
Also there's evidence that Mars may well be habitable for life. If so it could spread, through exponential growth, over the entire surface within decades, like the rabbits and other placental mammals spreading over Australia.
That would be the end of any chance to look at Mars is like in its current pristine state, and could delay our chances for decent understanding of early Mars by decades or centuries.
It could also cause big problems for future colonists on Mars if we do ever decide to colonize or terraform it. You are talking about seeding a planet with microbes from a human habitat, and letting them evolve in a radiative fashion and see what they turn into in conditions of near vacuum, and high levels of radiation, after all. Seems not at all impossible that the results could be microorganisms hazardous to humans and our habitats, and hard or nearly impossible to sterilize.
Then many ideas for terraforming Mars involve a careful process of introducing microbes step by step, with only plants to start with - and most of all, canobacteria for instance to generate oxygen. Animals and aerobes that eat the oxygen would only be introduced at a far later date. But colonists would introduce those right away, and it would be impossible to reverse this if they start to spread over the surface of Mars.
And - there are the warm seasonal flows,now known even in the equatorial region, probably involving liquid water, and the DLR experiments that suggest that lichens and cyanobacteria can survive on the surface of Mars possibly almost anywhere using night time humidity (same as causes the frosts on Mars).
At the very least this needs far more research and detailed understanding of conditions on Mars and enough knowledge to exactly reproduce conditions there, not just guesses.
But - there seems actually no benefit as far as exploration, for humans on the surface, just major issues.
A lot is made of the flexibility of humans on the surface. That's true of a planet surface with an atmosphere - even if you can't breath it. But spacesuits are clumsy, as you see with the ISS when astronauts find it tough to do even simple things because of the stiffness of the spacesuit gloves especially (because of the vacuum outside of the glove) - and humans can only get around on the surface for any distance if they carry many tons of equipment for life support with them as well in their rovers.
Spacesuits of course will be improved but so also will telerobots, easier and easier to control.
Machines can be light and agile, even light enough to fly - and can be controlled from orbit, saving humans the dangerous descent to the surface, and able to go to places humans could never go.
This idea of controlling them from orbit - can reduce the light speed delay to almost nothing would deal with just about all the issues that you get driving our rovers around on the surface of Mars from Earth and doing experiments there from Earth. There's no need to go to the surface for that. The HERRO study particularly found that it would get far more science done, for less cost, than a surface mission.
See
- How Valuable is Pristine Mars for Humanity - Opinion Piece?
- Would Microbes From This Astronaut Make It Impossible For Anyone To Terraform Mars - Ever?
- Why Mars is NOT a Great Place to Live - Amazing to Explore From Orbit - with RC Rovers, and Nature Inspired Avatars
- Life On the Edge In Cold Dry Deserts Of Mars - Dust Storms, And Contamination By Microbes From Leaky Spacesuits
- Need For Caution For An Early Mars Sample Return - Opinion Piece
SPINNING HABITATS
If you are going to live in artificial habitats, there's also far more space available to colonize as spinning habitats in space. That may surprise you, but work out the figures,there's far more potential in free space than on planetary surfaces, if you work out the amount of material available for shielding a calculation that goes back to the 1970s.
And - this is for large spacious habitats - okay you are surrounded by tons per square meter just as for Mars of radiation shielding - but - this is in free space so you can build it up into a big spacious habitat, kilometers across. Very hard to do that on Mars with same levels of shielding. And can control the environment, warmth of the tropics if you like, main problem in space is radiating the heat away not keeping warm.
- Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths
- If Mars Is For Hardy Explorers Only, Where Is The Best Place In The Solar System For First Time Colonists?
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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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