The affect of lower gravity on humans.

Canth · 2002-05-03 14:09:16

How will low gravity affect people visiting lower surface gravity planets, such as on an extended mission to mars (1-2 1/2 earth years), people born on earth but living for a long time on a lower gravity planet, and people born on a low gravity planet. Microgravity is known to cause muscles and bones to weaken significantly thus rendering astronauts having spent months in space temporary invalids upon there return to earth. I beleive it takes at least few days for them to recover much significant mobility and possibly weeks or more. There are apparently some long term affects as well including permanently reduced bone density. The bodies natural healing methods are detrimentally affected by microgravity. A cut dosn't heal in space. How would martian or lunar gravity affect the bodies regeneration and immune systems. Would a Martian or lunar born person be able to take a visit to earth. I think it would be very difficult and likely dangerous for a martian and and life threatning for a lunar person.
This topic was suggested by Adrian in the topic Mars Mission. Step 1. There is some extensive discussion of it there. Anyone who posted about this elsewhere feel free to copy your arguments/comments over here.

Adrian · 2002-05-03 17:14:24

This is an essential topic to discuss but frankly there has been very little research into the subject. Yes, I know that we've had at least a dozen serious studies into the effects of weightlessness on human beings, but zero-G and partial-G are two very different things. I believe that there are two overarching problems to consider.

1) In the development of the embryo and other sensitive systems, it is possible that axes or polarities of cells could be set up via the effects of gravity. Likewise, even in adult human beings, gravity could affect direction and magnitude of growth. Certainly in plants there are specialised cells which can 'detect' the direction of gravity and grow 'away' from it, vertically. If gravity does affect the growth of a human being in this way, I am actually optimistic that even the 0.38G of Mars would be sufficient to set up the necessary axes and orientations for development.

2) Muscle and bone growth are highly dependent on the stresses exerted upon them. You get serious atrophy of both in zero-G, and it is certainly possible that partial G on Mars could result in brittle bones and weaker muscles.

Possible solutions to the second of these problems could include drugs, exercise and weights on the body. The first problem would require nothing less than artificial or real (as in, Earth) gravity.

I am a biologist, so this is not just speculation but informed speculation. Even so, intensive research must be conducted on the effects of partial G on humans, through study of the lifecycles of higher vertebrates in some kind of centrifugal environment in orbital.

Canth · 2002-05-03 22:24:05

I agree. Such a study is planned by the mars society. They plan to put a satilite creating artificial gravity through centrifigal force with mice on it in orbit. The mice will then be returned after a significant stay at mars g. I beleive that they are considering flying this mission either independantly or aboard the ISS. A stay in orbitwould be about forty days. Some mice would be born and grow to udulthood at mars g. This should provide much needed data. If aboard the space station I beleive that the centrifuge could be reused allowing several generations of mice or several different studies perhaps involving other levels of force (such as lunar) or other animals such as reptiles or even fish and anphibians. Quite a scientifically worth while experiment.

Canth · 2002-05-05 14:57:27

To simulate a different gravity you simply change the speed at which the cetrifuge is rotating. You could use a space based centrifuge to simulate the gravity found on the surface or in the atmosphere of any of the planets in the solar system. An interesting experiment would be seeing the affect of the 2.5 (I think) gs experienced in a hot air baloon in jupiters atmosphere.

Adrian · 2002-05-06 13:17:21

Orodromeus: My speculation is that as long as a mammal develops in an environment with a uniform, non-negligible gravity (I'll throw out 0.1G as a guess), it will not suffer any lethal defects. That is not to say that it may be seriously impaired physiologically, e.g. reduced muscle and bone mass.

To me, the most important thing in mammal development is the setting up of the body plan, and ensuring that all the cells receive the appropriate growth signals at the correct time. I find it hard to believe that there are no signals that are somehow dependent on gravity (e.g. gravity could be used to orient the axes of cells or organs), but I don't think that 1G is required.

Still, much is unknown, and there could be many complicated factors. For example, reduced bone mass could very well result in a seriously impaired immune system. Reduced muscle mass could affect blood flow. Low gravity could affect the psychological development of mammals - genetically, we 'expect' our environment to exhibit various things, e.g. that falling objects will drop vertically at a certain speed. But then, the brain is a versatile and plastic thing. Who knows what could happen.

One thing is for sure - growth of a mammal in reduced G will impair its functioning as an adult.

For short term Mars missions, up to two years or more in length, I don't think the reduced gravity is a problem. 0.38G is still a fair bit, and astronauts will fare far better than those in zero-G. The real problem is if and when the colonisation of Mars takes place.

Canth · 2002-05-06 15:51:20

Exactly

Yang Liwei Rocket · 2004-03-10 15:21:17

Aussie Mice living on mars gravity...?

2004
.....
.....NASA spacecraft explore the surface of the red planet, Australian and US scientists are planning to study how mammals are affected by long periods in Martian conditions.
A space craft launched from Cape Canaveral in 2006 will take 15 mice "astronauts" into orbit around Earth, said Australian project leader and aerospace engineer Jason Hoogland of the University of Queensland (UQ).
The revolving craft would simulate the gravity of Mars - about 38 per cent of the gravitational pull of the Earth.
"When we basically get the mice out into earth orbit, they basically float around and feel zero gravity," Mr Hoogland said.
"We simulate the gravity on Mars by spinning at just the right rate for them."
UQ, the University of Washington and Massachusetts Institute of Technology (MIT) were collaborating on the project..........
.....
...
-Herald Sun

dicktice · 2004-03-12 09:33:51

Adrian: Good on you! I remember reading, quite recently, that 0.1 gee (or was it 0.01 gee?) is sufficient for germinating plant seeds to sort out which direction the shoots and roots direct themselves, under microgravity conditions. Further, the "vibrating platform" article in Scientic American (last year?) seemed to bear out the possibility of short-term exposure to body-longitudinal vibration (sinusoidal?) rates, frequencies being dependent upon which animal was being tested, for short times between long times of enforced inactivity (admittedly still under 1 gee conditions) of limiting bone and muscle deterioration. Obviously, such research could and should be underway right now, using mice, on the ISS.

SBird · 2004-03-22 12:13:38

I know that biotech these days is doing research on muscle growth and maintainance for people who have been rendered invalid because of hospitalizaiton. I wouldn't be suprized that in 10 years we've got experimental drugs that can prevent or reverse much of the negative actions of 0-G

dicktice · 2004-03-23 17:19:29

Sorry, but your "wouldn't be surprised" about so-called drugs isn't good enough, SBird. Not for we who don't have your presumed longer time of expectant life. I require discussing ideas and methods possible here and now. Why the heck, for example, not do scaled (1) sleep-centrifuge experimentation in orbit (when the politics of finance, etc. makes it possible aboard the ISS)? Ditto, regarding (2) orbital energy transfer tethers, and (3) light-sail feasibility, subsequent control techniqes and performance determinations.

Bill White · 2004-03-23 17:36:25

Sorry, but your "wouldn't be surprised" about so-called drugs isn't good enough, SBird. Not for we who don't have your presumed longer time of expectant life. I require discussing ideas and methods possible here and now. Why the heck, for example, not do scaled (1) sleep-centrifuge experimentation in orbit (when the politics of finance, etc. makes it possible aboard the ISS)? Ditto, regarding (2) orbital energy transfer tethers, and (3) light-sail feasibility, subsequent control techniqes and performance determinations.

SBirds catapult derived launch system for the Moon and Phobos (see other thread - catapults) creates a real opportunity for 1 gee sleeping and exercise capsules. Actually spin up to 1.1 gee or 1.05 gee for a better workout and slow to .8 gee for more pleasant sleeping.

12 hour zero gee (or 1/6th gee) work days followed by 12 hours of off shift at 1 gee.

dicktice · 2004-03-23 18:08:19

Great--but what about experimenting in the here-and-now? That's what we need for Mars First type travel durations. The essential facility (the only one I might add) is "up there" for the taking, so to speak. Carefully scaled experiment kits, with small animals, surely could be carried up aboard dedicated Progress transports as early as in 2005. (Any replies that reject this on the basis of cost alone, should in my opinion be considered mere cop-outs.

SBird · 2004-03-24 03:02:42

Don't forget that biotech is going extraordinarily fast these days. Also remember that the market for a drug that prevents muscle and bone atrophy is market with a potential for billions a year in sales. That pretty much guarantees that a big pharma will pick it up soon if not already.

This is my area of professional expertise - I'd predict 5-15 years before you see a drug along these lines going for FDA approval. With the advances in small molecule theraputics and gene array analysis and high througput proteomics, this is a rather low difficulty problem to attack these days. In terms of a Mars mission, there is a high probability that such a pharmaceutical will be ready in time.

MarsDog · 2004-03-25 05:16:34

A treatment to strenghten bones is to jump.
If you keep pounding your hand on the table, your hand develops stronger bones. (head against a brick wall also ?)
Short duration acceleration might be the answer.
-
I can imagine a machine to tumble and shake.
A large version of a tumble dryer without the heat ?

dicktice · 2004-03-25 09:53:51

How about replies from someone else besides drug-therapy specialists, preferabl whose expertise is in the field of physiotherapy, say, so that aspect of zero-gee conditioning can be addressed in addition to potential drug therapy? Time, in my view, is of the essence for the Mars First shots.

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#1 2002-05-03 14:09:16

Re: The affect of lower gravity on humans.

#2 2002-05-03 17:14:24

Re: The affect of lower gravity on humans.

#3 2002-05-03 22:24:05

Re: The affect of lower gravity on humans.

#4 2002-05-05 14:57:27

Re: The affect of lower gravity on humans.

#5 2002-05-06 13:17:21

Re: The affect of lower gravity on humans.

#6 2002-05-06 15:51:20

Re: The affect of lower gravity on humans.

#7 2004-03-10 15:21:17

Re: The affect of lower gravity on humans.

#8 2004-03-12 09:33:51

Re: The affect of lower gravity on humans.

#9 2004-03-22 12:13:38

Re: The affect of lower gravity on humans.

#10 2004-03-23 17:19:29

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#11 2004-03-23 17:36:25

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#12 2004-03-23 18:08:19

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#13 2004-03-24 03:02:42

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#14 2004-03-25 05:16:34

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#15 2004-03-25 09:53:51

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