Minimal Gravity

Terraformer · 2008-01-17 06:23:30

What is the minimum of G that humans need to remain healthy? I want to work out the minimum diameter a centrifuge would have to be.

cIclops · 2008-01-17 06:31:47

What is the minimum of G that humans need to remain healthy? I want to work out the minimum diameter a centrifuge would have to be.

Unknown. This is one very good reason to setup the Lunar Outpost, controlled experiments there at 1/6 g will help to find the answer. This is critical for living on Mars.

Mars_B4_Moon · 2008-01-17 10:07:14

Larger percentages of E gravity is something we might deal with better, if we could build a habitat to survive inside Jupiter a strong athletic astronaut would be able to survive inside one of these habitats, however they'd be getting a really good work out every time they tried to move. One third of Earth is supposed to be pretty safe. Mars at almost 40% of E gravity is closer to this figure. There will be more artificial gravity experiments done in space with small lab creatures to check long duration flights. The Moon is about a sixth, further problems arise in the lower gravity. On the Moon iwith 1/6 of Earth's gravity walking becomes difficult and its easier to bounce around rather than walk. Moon gravity will be an issue, plants might grow 5-7 times higher, the human body will face some deterioration but it might be something we can deal with. In the next few years mice, flies, toads etc might be contained inside a special habitat onboard the ISS and a centrifugal force will create artificial gravity, rats also get space sick. ESA and Russia also plan to launch a Foton gravity experiment, rumor has it China has something similar planned. People at MIT and Georgia Tech are working on experiments for a Mars gravity sat in 2011. Even a 19th of Earth gravity might help avoid the most severe of the micro-gravity health deterioration issues by keeping bones working and allow biological fluid settling. If Gravity and Gravity alone were an issue in space exploration then Venus would be the ideal world to settle, unfortunately the planet Venus has got a toxic, hellish climate and its temperature makes it totally inhabitable. One of the big problems I could foresee are future children who may be born on Mars trying to adapt to E gravity after they come back to Earth, if they don't already have the bone mass or muscle mass they will probably need artificial implants like something out of a Terminator film so they can return to a life on Earth. We don't know for sure about any of these stuff, most of it is speculation on paper because we haven't put humans into artificial gravity habitations yet.

dicktice · 2008-01-17 12:05:51

I've often wondered, since I'm getting on in age, if Earth gravity is necessarily optimum for human longevity. If, say, one lived on the Moon or Mars from birth, what might the average life span turn out to be--shorter, the same, or longer than here on Earth? How might this be investigated today? Perhaps populations of mice (say) born and living out their relatively shorter life spans than ours at various radii of a constant-speed centrifuge aboard the ISS could be used to form a first approximation answer to this question.

samy · 2008-01-18 16:53:36

if Earth gravity is necessarily optimum for human longevity

I'm not convinced that's been satisfactorily proven.

Common sense would suggest to me that mildly higher gravities (say, 1.1g or 1.2g) would correspond to constant workout, making us very athletic, low-fat and less prone to cardiovascular diseases since every time we moved it'd be like carrying some dumbells.

cIclops · 2008-01-18 17:33:03

Common sense would suggest to me that mildly higher gravities (say, 1.1g or 1.2g) would correspond to constant workout, making us very athletic, low-fat and less prone to cardiovascular diseases since every time we moved it'd be like carrying some dumbells.

Unlikely. Gravity has been constant on Earth since it was formed and certainly since life began. Why should an organism evolve to take advantage of something that never changes?

samy · 2008-01-18 17:51:01

Humans evolved to hunter-gatherers. Physically, we are mammoth-hunters. Our physiology is evolved to be at its best when we are regularly exerted during each day. Putting aside the concept of orgasms needing to evolve (which I don't think they need to, they're quite wonderful as-is), we are currently *lacking*, due to societal reasons, the physical exertion that our bodies are evolved to need to stay healthy.

Our bodies are evolved to require exertion. The current Western sedentary lifestyle does not automatically provide it. Hence, a higher gravity would only be restoring something that societal development took away.

It's like suddenly exhausting vitamin C supply in your area, by extincting oranges or something. Your body is still evolved to need it to stay healthy, but it's now gone from your world.

Terraformer · 2008-01-19 05:10:48

Putting aside the concept of orgasms needing to evolve (which I don't think they need to, they're quite wonderful as-is)

Eh? Where do Orgasms come into it?

samy · 2008-01-19 13:01:56

They were in cIclops' post but he seems to have edited it retroactively to cover up his activities.

Terraformer · 2008-01-19 15:23:59

Hehehe. lol lol lol.

John_Frazer · 2008-01-21 13:59:58

... Our bodies are evolved to require exertion. The current Western sedentary lifestyle does not automatically provide it. Hence, a higher gravity would only be restoring something that societal development took away.

As far as we know, the minimum to keep us healthy is one full Earth G.
We have absolutely no experience with low gravity, and the experience with microgravity paints a grim picture.

We do have some experience that says that low G will be bad, all the S.F. stories of long lives on the Moon or in low G to the contrary.
Marathon runners and others who constantly stress their bodies against gravity generally live longer than couch potatoes, and long-term patient bedrest involves virtually no stress against gravity. Wouldn't this seem to indicate that living in low G will make your heart & muscles atrophy, which generally leads to a lower life expectancy and less health?

Conversely, we do have a lot of experience with centripetal hypergravity (spinning habitats for higher than Earth G).
Uniformly, critters from plants to mice to chickens which are raised in hypergravity are more healthy, with longer life spans.
Rats have legs like little elephants and walk like super-rats, their hearts are huge strong dense nuggets of muscle. Generally, their legs are stronger up until about 3.5 G, when they no longer use their legs to get around...
There's a book dealing with topics of transhumanism, including space colonies to spread human and Gaian life across space. It's called "Great Mambo Chickens and the Transhuman Condition", because that's what the chickens were like, after being raised in 2.5 G

(and orgasms, like every other muscular response, are only improved by regular strenuous exercise. Do your Kegels)

samy · 2008-01-21 16:40:08

So in fact, higher gravity would indeed evolve orgasms!

dicktice · 2008-01-21 17:33:37

Concerning longevity, though: besides musclularity, long life to have any meaning would have to include the brain and the continued development of the mind. I guess my question regarding optimum gravity really means something between one gee and zero gee. Excercise in lower than one gee conditions could still be accomplished. In fact, strapping on wings and flapping about in the air would be much more fun than pushups. The fact that blood supply to the brain need not be at risk as opposed to pooling in the legs for instance, might contribute to healthier brains. But, really, since we admittedly haven't yet performe the requisit experiments (mice raised at graduated centrifuge radii) I declare the argument for optimum longevity vs. gravity to be still open to discussion.

Michael Bloxham · 2008-01-22 00:08:20

Alternative Theory (not sure if I subscribe to it, but sounds intriguing):

"The human body will adapt to remain healthy in its environment.

Yes, a man in zero-g will experience muscle and bone loss, and his heart may shrink, but this is because large energy-hungry muscles aren't needed to get around in zero-g. If his body kept these things, what useful purpose would they serve in an environment where it is impossible to fall and you get around by floating instead of walking?

The astronauts encounter problems because the change from full-g to zero-g is so sudden. Their bones demineralize so fast that their bodies have trouble getting rid of the liberated calcium. But they survive the adaption process, and once adapted, live quite healthily in zero-g.

The confusion on this matter arises because the current definition of 'healthy' requires a minimum bone and muscle mass (among other things) based on observed norms, which of-course, are biased towards terrestrial living."

cIclops · 2008-01-22 04:55:09

Conversely, we do have a lot of experience with centripetal hypergravity (spinning habitats for higher than Earth G).
Uniformly, critters from plants to mice to chickens which are raised in hypergravity are more healthy, with longer life spans.

How much longer is their life span? Is there any evidence that this will work in primates?

dicktice · 2008-01-23 21:12:19

This just in (tail-end item of CBC Daily Planet popular science TV program today): Cockroaches bred and raised in microgravity by the Russians demonstrate on Earth heightened physical activity, mental capacity, and (dare I hope?) longevity. I didn't have time to follow this up, but maybe someone will before I get around to it....

dicktice · 2008-01-23 22:35:56

Further re. the space cockroaches:

VORONEZH, January 17 (RIA Novosti) - Cockroaches conceived in space onboard the Russian Foton-M bio satellite have developed faster and become hardier than 'terrestrial' ones, a research supervisor said on Thursday.

The research team has been monitoring the cockroaches since they were born in October. The scientists established that their limbs and bodies grew faster.

"What is more, we have found out that the creatures... run faster than ordinary cockroaches, and are much more energetic and resilient," Dmitry Atyakshin said.

Cockroaches, as well as other types of insects, can give birth several times after one impregnation, and the cockroaches that conceived during the bio-satellite's September 14-26 flight have since given birth to their second and third batches of offspring.

"The second and third batches did not show these peculiarities of growth and physiology," the scientist noted.

'Ordinary' cockroaches are already known for their extraordinary resilience. Some species can last almost an hour without oxygen or a month without food, and are able to withstand high doses of radiation.

The September 14-26 flight was part of an ongoing experiment into the effects of space flight by the Institute of Biomedical Problems (IBMP). The creatures were sealed in special containers, and a video camera filmed them during the flight.

Mars_B4_Moon · 2008-02-11 03:51:35

This just in (tail-end item of CBC Daily Planet popular science TV program today): Cockroaches bred and raised in microgravity by the Russians demonstrate on Earth heightened physical activity, mental capacity, and (dare I hope?) longevity. I didn't have time to follow this up, but maybe someone will before I get around to it....

amazing news item

akinkhoo · 2008-02-29 10:43:07

Common sense would suggest to me that mildly higher gravities (say, 1.1g or 1.2g) would correspond to constant workout, making us very athletic, low-fat and less prone to cardiovascular diseases since every time we moved it'd be like carrying some dumbells.
Unlikely. Gravity has been constant on Earth since it was formed and certainly since life began. Why should an organism evolve to take advantage of something that never changes?

even heard of a term: "side effect". just because we weren't build to take advantage of it, doesn't mean we won't. we will only get answers from science and experimentation.

RobS · 2008-03-01 10:41:07

If you want your body to experience the equivalent of higher gravity, all you have to do is put on an extra 20 or 40 pounds. That added weight, being carried around all the time, is a strain on the cardiovascular system. Conversely, losing a bunch of weight is better for your cardiovascular system. Just based on that I suspect one's heart and bones can handle the range of 0.7 to 1.3 gees pretty well, because they already do.

You can extend that range by sewing large pockets into clothes where one places weights. I suspect if we ever can raise kids on Mars, that would be a wise strategy; if the kids ever want to fly back to Earth, their hearts and bones have to be capable of adjusting to the gravity. I am not so sure it is practical on the moon to add weights to pockets because they'd have to be quite large.

On either the moon or Mars, jumping would be an excellent exercise (and fun; think how high you'd go on the moon!). Your muscles would have to work just as hard on any of those bodies as they would on the Earth, your bones would deal with the same acceleration/decelleration stresses, and your heart would get the same workout. But if gravity gets much below 0.16, vertical jumping faces other problems; you'd go too high and it'd take too long to come back down for the jumping to be aerobic. On the other hand, at very low gravities, inside habitats with a reasonable fraction of the Earth's atmospheric pressure, you could strap wings to your arms and fly. Maybe people on Ceres would end up with massive arm muscles and wimpy leg muscles!

Medical research will be necessar to see whether any of these strategies will be sufficient. My guess is that as long as you have a reasonable amount of gravity to work against, you can exercise enough to maintain bones and the heart. Of course, it may take so long, a lot of people won't want to do it.

-- RobS

cIclops · 2008-03-01 13:56:49

Does this mean all those obese kids will have a bright future on Mars?

louis · 2008-03-28 10:10:27

Has any research been done into mimicking earth gravity through weight bracelets on various joints in the body: wrists, elbows, neck, waist, knees and ankles. In a 0.38 G environment like Mars I think this could be quite effective, certainly in countering bone loss.

New Mars Forums

Announcement

#1 2008-01-17 06:23:30

Re: Minimal Gravity

#2 2008-01-17 06:31:47

Re: Minimal Gravity

#3 2008-01-17 10:07:14

Re: Minimal Gravity

#4 2008-01-17 12:05:51

Re: Minimal Gravity

#5 2008-01-18 16:53:36

Re: Minimal Gravity

#6 2008-01-18 17:33:03

Re: Minimal Gravity

#7 2008-01-18 17:51:01

Re: Minimal Gravity

#8 2008-01-19 05:10:48

Re: Minimal Gravity

#9 2008-01-19 13:01:56

Re: Minimal Gravity

#10 2008-01-19 15:23:59

Re: Minimal Gravity

#11 2008-01-21 13:59:58

Re: Minimal Gravity

#12 2008-01-21 16:40:08

Re: Minimal Gravity

#13 2008-01-21 17:33:37

Re: Minimal Gravity

#14 2008-01-22 00:08:20

Re: Minimal Gravity

#15 2008-01-22 04:55:09

Re: Minimal Gravity

#16 2008-01-23 21:12:19

Re: Minimal Gravity

#17 2008-01-23 22:35:56

Re: Minimal Gravity

#18 2008-02-11 03:51:35

Re: Minimal Gravity

#19 2008-02-29 10:43:07

Re: Minimal Gravity

#20 2008-03-01 10:41:07

Re: Minimal Gravity

#21 2008-03-01 13:56:49

Re: Minimal Gravity

#22 2008-03-28 10:10:27

Re: Minimal Gravity

Board footer