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first of all, earth's gravity has it's own adverse effects. ever seen an old person hunched over? thats probably because over 60 to 80 years, gravity has worn out the spinal cord, which is responsible for bearing the weight of the body.
perhaps earth can provide calcium pills to help keep bones strong. im no biologist, so i cant say the effects of martian gravity on baby development. thats something for an experienced doctor to say.
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Decalcification of the bones is caused by osteoperosis. Human bones have a constant process of renewal and tuning. One enzyme disolves bone mass while another builds bone mass. The enzyme which builds bone mass is increased when nerves are stimulated by stress on the bones. The process of bone building and bone dissolving is reduced with age, and when that gets unballanced it results in bones loss. Reduced gravity may result in less "hunching over" but it will also cause less stimulation of the nerves which build bone mass so expect the bones to become even more brittle. Osteoperosis is a syndrome; the solution is telomerase and human growth hormone. Someone who is young or middle-aged would find their bones optomize themselves for that gravity. And, yes, excercise that produces stress on bones does build bone mass in anyone who is not a senior citizen.
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One enzyme disolves bone mass while another builds bone mass. The enzyme which builds bone mass is increased when nerves are stimulated by stress on the bones. The process of bone building and bone dissolving is reduced with age, and when that gets unballanced it results in bones loss.
i just did a biology paper, and part of it was research on future spinal injury treatments. medications are being developed that stimulate enzymatic and protein activity (for bone repair). i don't see why this couldn't be done on mars.
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Mars's low gravity has the potential to affect more than just our skeletal system. There's still questions on how it affects the muscular and circulation systems. Personally I kind of suspect these problems can be overcome with exercises but I think there's a real danger that someone born on Mars might not develop healthily or might never be able to visit Earth. I also wonder how the placenta and fetus will fare with the higher surface tension of water that will exist on Mars. Hopefully the biosatellite will shed positive light on the affects of being born in lowgrav.
To achieve the impossible you must attempt the absurd
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One thing that occurs to me: astronauts going outside on a regular basis will be wearing space suits weighing almost as much as themselves. This means their bodies will be experiencing a vertical stress closer to 0.75 gravities. Sometimes it will be more, because their bodies will still be dealing with the momentum of all that mass when walking. Furthermore, the air pressure in suits will make bending and moving arms more difficult.
Physicians tell us on Earth that we need to get about a half hour of exercise two or three times a week to keep our cardiovascular system functioning well. If a geologist is going outside for two or three hours at a time three or four days a week, you'd think that amount of exercise would have a big impact on the skeletal system and cardiovascular system. But only medical research in a 0.38 gravity environment will verify that guess.
Of course, exploring the moon and putting astronauts there for several months at a time would provide a very valuable datapoint.
-- RobS
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I think there's a real danger that someone born on Mars might never be able to visit Earth.
Yeah,
I heard somewhere that the pressure pressing down on us was about the wieght of a small car. I dunno how much a small car weighs but im guessing about 500 to 750 kg which is quite a bit.
If you were born on Mars with a gravity of about a 3rd of that it would be about *gets out calculator* 166.5 to 249.75 kg. If a Martian person decieded to go to Earth after being on Mars he/she would be like crushed under 3 times the wiegh his/her body were used to carrying, which would probably stuff up pretty much every system in his/her body.
I think thats right.
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it would be hard to say if they would be crushed. we dont spontaneously expand upon being subject to zero G. i suppose a trip between earth and mars could utizilize a device that slowly raises the G's or lowers the G's to the proper amount for the destination, sort of "weaning" the gravity level. 6 months is a decent amount of time for the body to adapt.
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I did'nt mean literally crushed, It was figurative.
But it would be a crushing sensation which would make every-day taskes quite difficult.
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it would be hard to say if they would be crushed. we dont spontaneously expand upon being subject to zero G. i suppose a trip between earth and mars could utizilize a device that slowly raises the G's or lowers the G's to the proper amount for the destination, sort of "weaning" the gravity level. 6 months is a decent amount of time for the body to adapt.
The crux of the problem though is whether the bones and tissues of someone born on Mars would be inherently incapable of surviving the loads put on them by Earth's gravity. By analogy we could try to make people resistant to Jupiter's gravity by gradually cranking up the g-factor but it wouldn't work as our bodies are inherently incapable of supporting that kind of gravity. Anyhow I've got something of a hypothesis that at this point in our evolution the components of our bodies are more determined by genetics rather than by gravity so I think someone born on Mars will have a body similiar in strength to someone born on Earth but I guess we'll have to wait and see.
To achieve the impossible you must attempt the absurd
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Hi Echus!
I suspect you're confusing the pressure exerted by Earth's atmosphere with the gravitational field.
I remember seeing pictures in books of a man balancing three elephants on a plank on his shoulders, with the notes under the picture explaining that this was the equivalent of the air pressure on a human body at sea-level. Presumably they calculated this from the surface area of the average human and the sea-level pressure of 14.7 lbs/sq.in.
This is not the same thing as gravity.
But essentially you're right in saying a human arriving on Earth after a long stay on Mars would feel like their flesh and blood had turned to lead! And while their bones might also feel like lead, they might be more like chalk in terms of strength!
I guess most people at New Mars already know my views on native-born Martians visiting Earth .... I think they simply won't be able to!!
I also think a Mars Direct mission without artificial gravity (i.e. 180 days in zero-g, 500 days in 0.38g, and another 180 days in zero-g) will pose extremely serious problems for returning astronauts.
I could be wrong of course. But nobody's convinced me of that yet!
???
The word 'aerobics' came about when the gym instructors got together and said: If we're going to charge $10 an hour, we can't call it Jumping Up and Down. - Rita Rudner
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I suppose one solution for Martian colonists could utilize to counter the effects of the weak gravity is frequent use of a centifuge...perhaps a spinning, doughnut-shaped room with movable floor plating to simulate one Earth gee.
I haven't a clue whether spending an hour or so each day under artificial Earth gravity would be enough to counter the weakening effects of Martian gee, but it certainly couldn't hurt. Also, a workout program with heavy lifting of weights should help counter the weakening of bones and muscles, especially if you had machines that would place extra stress on various parts of the body. As for babies...we'll need to raise a lot of monkeys, etc, in the low gee to see how they do before we even think about having babies on Mars...
B
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Hi all,
Decalcification would not be that bad if it becomes a physiological adaptation process to the mars gravity, one among many other biological ways that the mammalian body could use to adapt on Mars. Bones on Mars don't need as much calcium as they need on earth and cartilaginous bones could have enough stiff to support a 40 kg (mars gravity) smaller body, like for children. Like I said in another thread, adult Martians could be like neotenic humans: kids with cartilages which never, or incompletely resorbs at adult ages. As you know, one important function of the cartilage in juvenile bones is that it promotes growth and bones elongation, but here on Mars, without much physical stress for the hormonal system to stimulate the forming bones and muscles, the presence of more cartilage in bones doesn't mean the bones have to be necesseraly very elongated, meaning that the neo-martians don't have to be very tall.
The bones formation and many other biological processus have to be naturally adatped to Mars conditions. I am not a fan of trying to keep terran characteristics at all cost to slow down that processus. I don't believe exercise is the solution, the colons will have enough work to do, they won't need to add 4 hours of bicycle a day.
Technology and tools will be sparse, colons will rely only on local ressources and frugal technology, using local stones to built their houses, lifting these stones with their own hands maybe, that's enough exercise.
The health problems, as usual, will be mostly for the immigrants, not for the first generation of martians, because by definition, if the neo martians survive the fetal and embryonic development in Mars gravity, they are in business. Those who don't, abortion etc, obviously won't transmit their genes combination further, that's darwinian processus. Then the second generation will be even more fit than the first.
But for the immigrants, no such hope, except medical treatments to relieve their inherent inadaptation.
The first problem is really the embryogenesis. On earth, the human brain takes 9 months, longer than the rest of the body. This is very different of the other mammals, even chimpanzees, whose gestation is usually in the 7/8 months range. So what if the different day duration and gravity impact the gestation time in homo sapiens more than other species ?
On the long term, I think humans can settle on Mars but after an inconvenient initial period with high rate of abortions, malformations, cancers and so on.
For that reason, doctors and molecular biologists will be as useful on Mars than rocket scientists or chemist.
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If nothing else, you can insert weights into special pockets in your clothes. It would be a pain walking around with them, but it would provide the stress the bones need.
-- RobS
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