Max Habitable G: What is the Limit?

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In summary, the maximum gravitational acceleration that a human being can live at is not a simple answer as it depends on multiple factors such as air density, atmospheric pressure, and the individual's physical adaptability. However, a general estimate is 3G, as higher G values can cause problems such as bone demineralization and cardiovascular strain. Additionally, atmospheric pressure is not directly related to gravitational acceleration, as it depends on the amount of atmosphere and its density. Therefore, the maximum habitable g cannot be determined without additional information about the planet's atmosphere and the individual's physical adaptability.
  • #1
stringue
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Maximum Habitable G??

Hi, read on the net about the detection of a 5 * Earth Mass planet today orbiting around Gliese 581, and this got me thinking about the titled question which I have been unable to answer for myself.

What is the maximum 'g' (gravitational acceleration) that a human being can live at?

I was thinking in the context of settling other worlds, by 'live' I think some reduction in quality of life at higher g would be acceptable ie. reduced lifespan, reduced walking distance etc. but the 'guinea pigs' would have to be able to live and colonise said planet. Oh also no fancy high-tech aid's to raise the figure, maybe with the possible exception of walking stick's, zimmerframes, and maybe the use of wheelchairs.

Thanks!
 
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  • #2
Our entire physiology is adapted to our current gravitational acceleration on Earth.

Lower G values cause things like bone demineralization. Higher G values put tremendous strain on the circulatory system, for example. The cardiac stress of living at 5G's would be really deleterious for an adult. --My opinion based on what I've read about human centrifuge experiments.

Air density/pressure would also be another long term problem. Absorption of other gases into blood starts to occur at higher ambient air pressures. I guess we could assume 5 atmospheres, which is about like scuba diving at depths a lot greater than 66 feet (3 atmospheres) - the point where nitrogen narcosis starts to occur.

Plus, assuming there are animal-like beings there, we would be paper-tissue-like beings compared with them. If they wanted to shred us, it's be no problem.
 
  • #3
jim mcnamara said:
Plus, assuming there are animal-like beings there, we would be paper-tissue-like beings compared with them. If they wanted to shred us, it's be no problem.
Who says that? Why?
 
  • #4
Mkl - have you ever been in high G? It's a lot harder to move effectively.
 
  • #5
Hi,
thanks for the reply's,

If the air toxicity is the first limiting factor without respiratory aids, does this mean 3g (equivalent to quoted 3 atmospheres?) is the most acceleration a person can live at?

Otherwise does anybody know then at what surface acceleration nitrogen narcosis becomes a problem - I suppose for this question there are lots and lots of variables (ie. ratio of nitrogen in atmosphere) but if it makes it any easier, just assuming this planet were Earth with a stronger gravity and the same Earth atmosphere.

Also by the way, though Gliese 581c is aprox 5 Earth mass its surface acceleration is apparently 2.2g according to a few post's I have seen on the net, 1 referenced here:
http://www.astronomy.com/ASY/CS/forums/340277/ShowPost.aspx"

I am sure any developed unfriendly native fauna would have a physical advantage over us but perhaps potential colonists could avoid them, or use high yield weapons to deter them if neccesary.
 
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  • #6
Gravitational acceleration has NO RELEVANCE to atmospheric pressure. On the moon there is 1/6 G but absolutely no air (not 1/6 atmospheric pressure).
 
  • #7
Well I was really interested in a number for maximum habitable g, 3 seemed reasonable at the time,

Are you sure g doesn't affect surface pressure?, The moon has no atmosphere to begin with so it's a little unfair to suggest it wouldn't have 1/6 atm at the surface as there isn't any air to begin with, anyways.

Assuming air is hard particles, then pressure is the force these particles exert on a suface right? If we assume the 'surface' is the surface of world X and pressure is then the force exerted on this surface (is this ok so far?)

Say world x has 1 surface g, but we increase it's density (and only its density no other change at all, no more or less air, no different air composition etc) so that it now has 2 surface g.

With the changed acceleration component on our particles towards the surface, doesn't that result in a greater density of particles/particle velocity (+interactions) towards the surface, and therefore (as the surface isn't going anywhere, assume its perfectly static and hard) greater 'pressure' on the surface??

Hope that was a pretty logical question, am i right or way off track? :) and still want a value for maximim habitable g (assume Earth but greater density alone) :D
 
  • #8
Air pressure is the weight of the air column above the sensor. If there is more air there is more weight. Gravity alone says nothing about the amount of atmosphere of any given planet but acceleration due to gravity does determine how much weight (pressure) there will be for a given amount of atmosphere. A larger planet with a much thinner atmosphere than our own could have a pressure equal to that of earth's. An earth-sized planet with much more atmosphere than we have would have a higher pressure.
Gravity alone cannot provide any information about pressure.

The moon example was provided only to illustrate that there is missing information...
 
  • #9
Higher g values would put a stress on ones cardiovascular system, but that system can increase in strength. I doubt anyone knows what that limit is.
 

FAQ: Max Habitable G: What is the Limit?

What is the maximum habitable G-force that a human can withstand?

The maximum habitable G-force that a human can withstand depends on a variety of factors, such as age, physical health, and training. Generally, the limit for sustained G-force for a healthy human is around 5 Gs, but it can vary from person to person.

What happens to the human body at high G-forces?

At high G-forces, the human body can experience a variety of physiological effects. These can include loss of consciousness, difficulty breathing, blurred vision, muscle strain, and even organ damage. The severity of these effects depends on the duration and magnitude of the G-forces.

What are some ways to mitigate the effects of high G-forces on the human body?

There are several techniques that can help mitigate the effects of high G-forces on the human body. These include wearing specialized pressure suits, using G-suits that apply pressure to the legs to prevent blood pooling, and practicing special breathing techniques to maintain blood flow to the brain.

Can humans be trained to withstand higher G-forces?

Yes, with proper training and conditioning, humans can increase their tolerance for G-forces. Pilots, astronauts, and military personnel often undergo specialized training to prepare their bodies for high G-forces. However, there is a limit to how much G-forces a human body can withstand, and it varies from person to person.

What is the highest recorded G-force that a human has survived?

The highest recorded G-force that a human has survived is 46.2 Gs, experienced by Formula One driver David Purley in a crash during the 1977 British Grand Prix. However, Purley was in a state of unconsciousness during the peak G-forces and ultimately did not survive the crash.

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