Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

atitarev · 2004-07-09 15:27:06

Let's make the flaw of low gravity to an advantage.

If in low or microgravity and a thick enough atmosphere we would be able to just attach the wings and fly! Then people should do just that . Heavy cars could be driven by pedals - like bikes. Flying not walking - cycling rather than driving wil make up for the loss of gravity. Humans may evolve into a new flying species with the time (only joking but you get my point).

MarsDog · 2004-07-10 13:11:33

It comes down to:

Even 1G, on Earth, is not habitable without exercise.

dicktice · 2004-07-10 13:14:26

One generation at a time, Atitarev, please: A functioning set pair of flapping wings would suit me. A "Flying Wing Suit" in every Luna City closet, springs to mind.

dicktice · 2004-07-10 13:32:44

It comes down to:
Even 1G, on Earth, is not habitable without exercise.

Not so fast: Less than 1G, with exercise, hasn't been checked out yet, to see if it might contribute to a longer average life-span--of 150 years, say. We spend so much time learning about stuff, it's a rotten shame we don't have more time while we're still in shape to actively use all that learning, eh?

MarsDog · 2004-07-10 14:31:33

Both gravity and exercise produce stress on the body.
The body develops in response to the stress.
-
Gravity produces static stress.
Exercise produces short duration impulses of stress.
Gravity, by itself, cannot produce short duration impulses;
Hence, Earth is not habitable without exercise.

Shaun Barrett · 2004-07-10 20:55:15

We can't know the absolute effect of low-gravity living on human physiology, without doing the experiments.
But the relative effects of different gravity fields can be estimated with some degree of accuracy, I think. What concerns me is the effect of moving from Mars to Earth or the Moon to Mars, say. If we're going to be a space-faring race, with many homes on many worlds, won't we want to travel from one to another?
Just imagine that the blood in your vascular system is suddenly swapped for a liquid which is equally life-supporting but weighs 2.6 times as much as normal blood. What would that do to your heart?
This thought experiment represents the physiological equivalent of a human, acclimatised to martian gravity over a long period of time, coming to Earth for a holiday or to live permanently. Remember, also, that the heart is not only coping with much heavier blood but also with the added strain of the body working 2.6 times harder to lift anything or even just to stand up!
Is this survivable?

Or, assuming humans can adapt to living on Ganymede, say, do we just leave them there - effectively banishing them from Earth and even Mars, forever? (I suppose they could visit Luna and Titan for a vacation, though .. ) ???

atitarev · 2004-07-11 00:09:28

Imagine for a moment that the answer to the experiments are negative - and that at least humans born and grown up on a planet of one gravity group can't visit/move to a higher group (very likely outcome): From the Moon to Mars or from Mars to Earth, then what? Will the colonization stop? It will deter a lot of people but it won't stop if these new homes are attractive enough, enthusiasts might go even if they are not so attractive.

Not very likely that people will rely on exercises to stay fit. Too many people are too lazy or too busy to exercise. We will just end up with races that can live only in their gravity group.

Shaun Barrett · 2004-07-11 01:50:29

Back in September 2002, a few of us here were discussing similar gravity problems with specific regard to the colonisation of Mars. (It was on Page 2 of 'Plans, plans, plans', which is on Page 23 of 'Human Missions'.)

If any of our newer recruits to New Mars are interested to see what's gone before, they can http://www.newmars.com/forums/viewtopic … 1766]click here.

The circular railway device, with gimballed carriages, was suggested by Bill (White) to fend off the deleterious effects of 0.38g but could just as easily be used on any moon or planet to create an artificial 1g environment.
If a full 1g is not required, then any level of 'gravitational field' between that of the celestial body in question and 1g can be arranged by varying the radius of the circular track and the velocity of the train. (While there is no theoretical limit to the maximum g-force which can be generated, obviously the natural gravity of the moon or planet is the minimum.)

atitarev · 2004-07-11 05:33:38

Back in September 2002, a few of us here were discussing similar gravity problems with specific regard to the colonisation of Mars. (It was on Page 2 of 'Plans, plans, plans', which is on Page 23 of 'Human Missions'.)
If any of our newer recruits to New Mars are interested to see what's gone before, they can http://www.newmars.com/forums/viewtopic … 1766]click here.

The circular railway device, with gimballed carriages, was suggested by Bill (White) to fend off the deleterious effects of 0.38g but could just as easily be used on any moon or planet to create an artificial 1g environment.
If a full 1g is not required, then any level of 'gravitational field' between that of the celestial body in question and 1g can be arranged by varying the radius of the circular track and the velocity of the train. (While there is no theoretical limit to the maximum g-force which can be generated, obviously the natural gravity of the moon or planet is the minimum.)

Thanks, Shaun. I was sure this topic had been covered in this forum one way or another.

My conclusions so far:

People can stay healthy without too much effort in the low and microgravity using the accelerators or, with some effort if exercising.

Some people may decide just to adapt to their new environment without caring to return to Earth.

Human missions are possible - including long-term and the low gravity will not be a show stopper provided the accelerators or other devices are provided or if exercise is mandatory and possible during the missions.

There some benefits of the low and microgravity - more work could be done, lifting will be easier. Special useful vehicles could be designed to both exercise and doing something useful. New sports and variaions of existing sports could be created including skydiving. Titan is ready for testing this approach as it is - don't forget some warm clothes and oxygen supply (see Terraforming Titan thread).

Sick and very old people may find it relieving to move to move low gravity objects.

I'll be watching the gravity experiments and hopefully the future technology and medicine wll have more answers to low gravity issues.

Shaun Barrett · 2004-07-11 07:41:52

Yes, Anatoli.
The results of the orbiting centrifuge experiment on the 'mousetronauts' will be absolutely fascinating! I can't wait to see what happens because it has such a direct bearing on the colonisation of Mars.

My feeling is that mammals will probably cope well enough with martian gravity but I'm not entirely sure - which makes me a little nervous!

Ian Flint · 2004-07-11 09:28:04

I'm working on a book -- ok, just bouncing some ideas around for a book -- about this very topic. In it there will be huge rotating cities to produce 1g. There will also be those that embrace Mars' gravity for good or ill.

Grypd · 2004-07-11 13:04:26

Being tested by i believe Robert Gordon university is a machine you stand on and it vibrates your leg muscles causing them to stretch and unstretch rapidly.

This seems to help reduce muscle wasting due to low g it is currently at the stage of a prototype being tested on ESA's "Vomit comet" over bordeaux.

dicktice · 2004-07-11 13:23:26

Now there's a new approach: Large rotating areas. I'll probably get shot down for this, but how about experimenting on Earth--not with centrifuge arms in the ordinary sense--but with 100- to 200-foot diameter spinning surfaces, something like "funhouse" rides I remember in my (ahem) youth. Here's a brainstorm offering, off the top of my head, to see what might happen to us, over time, on the Moon or Mars:

It's a bit like being a "Flatlander," in that you remain essentially prone in a kind of widened telephone kiosk, of which there are three (say) spaced around this spinning disc which floats on a cushion of air and is driven from a large, hollow hub. Services such as food and drink, instruction and advice, health consultations, and entertainment, changes of clothing, are delivered from the hub "down" to the kiosks (in the gravity sense, but actually horizontally) to the occupants of the kiosks. Waste products are rinsed away down the drain, to be flung into a concentric gutter from the periphery, and sluced away. Each kiosk can be let "down" from and hauled "up" to the hub by the conductors, who maintain constant communication with each occupant, via closed-circuit tv. The occupants are free to move side-to-side, from living, to shower, to toilet space within their respective kiosks each of which could be at a different gravity simulation radius. They can draw up their legs to "sit" upon folding seats, as necessary, and folding tables (airline style) are available for eating, etc. Normal sleeping cycles would be simulated by hauling the kiosks "up" to the hub for eight hours "in bed" for 8 hours out of every 24. The "sky" would be a projection from the hub of real cloud formations, birds, etc. by means of IMAX optics, with sounds if desired, and times of day and night, onto the inside of an inflated dome which shelters the whole shebang. Gee, that sounds almost like it might be fun!

Rxke · 2004-07-11 14:40:19

Has that 'shaking-device' not been tested on one of the Euro-SpaceLab missions?
And IIRC, they had some sort of 'bone-cells' (forget wich) they subjected *intermittently and in fairly short 'sessions'* to g-forces by vibrating, and they showed the same characteristics as the test-sample on Earth, ie: test was rather successful.
(Ok, that was comparing between 0g and 1g, but i guess that bodes well for the future..)

RobS · 2004-07-11 18:32:40

On asteroids (and in orbit), rotating habitats would be the way to go. Think of them as spinning apartment buildings, probably at least fifty meters in diameter and rotating 3 or 4 times per minute to create 1/3 to 1/2 terrestrial gravity inside. Of course, "down" would be at right angles to the surface pf the asteroid, but that's okay. One would go to the hub from one's apartment, then turn 90 degrees and descend to the asteroid's surface through the hub. Then fly with wings through the air of the dome or lope through long underround tunnels to other spinning structures to go to work, school, shopping, etc.

I doubt this would be necessary on Mars, but who knows. The floors would have to be tilted to be "flat" because down would be a combination of Mars's pull in one direction and centrifugal force at right angles. On the moon, such rotating habitats with tilted floors might be becessary if 1/6 gravity proves to be unhealthy long-term.

-- RobS

Ian Flint · 2004-07-12 09:13:01

I've done some calculations concerning centrifuges on Mars and the Moon. My math is a bit rusty, so please correct me if I missed anything.

I used the artificial gravity equation from Zubrin's book and the http://www.usna.edu/MathDept/mdm/pyth.html]Pythagorean Theorum to come up with the following:

Artificial Gravity: F=(0.0011)W^2R
F = Force in Gs (Earth Gravity is 1G)
W^2 = rpm squared
R = Radius in meters

Pythagorean Theorum: A^2 + B^2 = C^2

The downward force of Mars Gravity (.38g) plus a horizontal force of .925g equals a diagonal force (felt inside the centrifuge) of 1g -- 0.38^2 + 0.925 ^2 = 1.

Since, in a centrifuge, the Mars gravity is only 7.5% of the 1g force, a person inside would be standing up almost horizontally. The following chart compares various radii (in meters) with their corresponding revolutions per minute:

Radius (m) | rpm
---------------------
5 12.97
10 9.17
50 4.10
1000 0.92

If you decided to make circular habitats to spin on Mars, they would have to be sent in pieces. The 10 meter radius habitat would be pushing the limits for launching in one piece, and the spin rate is a bit high. I think 6 rpm is about the tolerable limit for humans. For the Moon the rpm goes up just a little bit, about 10%.

These conclusions all assume that 1 g is necessary which I hope is not the case.

atitarev · 2004-07-13 05:36:14

It seems like we do have a few solutions. Thanks, guys.

-----

Thanks to Cindy (ecrazer_l_infame) I've got the link to Dr R. Zubrin's speech on terraforming Mars:

http://www.universetoday.com/am/publish … 004]Robert Zubrin's interview on Terraforming

I quote (sorry for crossposting but it's relevant here)

AM: Who should the first human colonists to Mars be and how should they be chosen? Since Martian gravity is one-third of Earth's, wouldn't bone and muscle loss, along with radiation, make colonization a one-way journey? What are the implications of what, from an Earth-perspective, is exile?
RZ: Life is a one-way trip, and we are all permanently exiled from our past. In that sense Mars colonists, and all colonists, are no different from anyone else. It is just more apparent in their case, as in addition to leaving behind the time of their past, they also leave behind the place. But in so doing, they gain the opportunity to create a world where none existed before, and thus gain a form of immortality that is denied to those who are content to accept the world they are born in.

That's exactly my point when we talk about colonizing small worlds. Yes, there is danger of never being able to return to Earth (not proven yet, and could probably be fixed with some technologies) but the pioneers will become immortal.

Shaun Barrett · 2004-07-16 05:16:39

Hi Ian!
I think your mathematics look pretty good, rusty or not!

A little bit of trigonometry reveals that people would indeed be standing close to horizontal in the example you calculated - just 22.3 degrees off horizontal. But they wouldn't be aware of it, of course.

Ian Flint · 2004-07-16 14:02:43

Shaun,
Can you show me the Trig calculations. My gears have completely rusted over in that area.
I can't wait to find an old textbook.

--We wants them...my precious calculations...let us just borrow them for a while...MY PRECIOUS!!!--

Wow, I really do scare myself sometimes...the inner nerd awakes!

BWhite · 2004-07-16 14:27:05

Ian, does this site help?

http://www.shunn.net/cv/toolbox/centrif … rifuge.cgi

Ian Flint · 2004-07-16 15:04:35

Ian, does this site help?
http://www.shunn.net/cv/toolbox/centrifuge.cgi

http://www.shunn.net/cv/toolbox/centrifuge.cgi

Not really. First of all I don't understand what he means by delta T. And second, I already know (from Case for Mars) the equation for artificial gravity in free fall -- F=(0.0011)W^2R (see a couple posts above).

What I want to know more about is spinning a torus shaped habitat on a planetary body. Here you have gravity working in two directions -- pulling from the center of the planet, and pushing away from the center of the torus. At what angle do you set your floor?

dicktice · 2004-07-17 13:17:06

The "floor" would remain parallel to the spin axis, as long as one remains prone with the head "up." But one's thickness naturally would be acted upon simultaneously by Earth's 1-gee. Would this be important for the human frame, I wonder? Probably not. So the simulation could be close enough, therefore, to affect the body the same as a bed-ridden patient (as has been reported by the Russians). By spinning-up, then, the affects of different gravities might be investigated pretty realistically, without leaving Earth--right, maybe, or crazy?

Shaun Barrett · 2004-07-18 00:39:42

Hi Ian!
It's difficult to describe this without drawing it but it only involves one right-angled triangle, so I'll give it a go.
It involves the same triangle you would have used when you invoked Pythagoras to calculate the amount of centripetal acceleration needed, in conjunction with Mars' 0.38 downward acceleration, to obtain 1g on the floor of the centrifuge.

Consider a triangle ABC, where the angle A^ is 90 degrees.
The line AB, which we can make vertical, is 0.38 units long to represent the 0.38g of downward acceleration on Mars.
The line AC, which we can draw horizontal, is 0.925 units long, as you calculated, to represent the centripetal acceleration of the centrifuge.
The hypotenuse, BC, is 1.0 unit long and represents the 1g we require the centrifuge to provide to the occupants.

It can be seen that the angle which the occupants in the centrifuge will make with the horizontal, is represented by the angle C^. This is what we want to find.

The sine of C^, being the ratio of the 'opposite' side over the hypotenuse, is 0.38/1.0, or 0.38.
Therefore C^ is arcsin 0.38, or 22.33 degrees

In the discussion we had about this kind of device previously (involving a train running on a circular track inside a tunnel to provide radiation shielding), it was suggested that the cars (if you're American) or carriages (if you're British) should be gimballed. This saves you having to construct the floor at any particular angle, since the carriage will swing out until the floor automatically feels like it's horizontal, regardless of how much 'gravity' you require and how fast the centrifuge is moving.
In the case above, the floor will swing out until it makes an angle of 67.66 degrees with the horizontal. Inside the carriage, the occupants will feel like they're upright in a train on Earth, instead of almost horizontal on Mars! (No windows allowed, of course.)
If the circumference of the circular rail is made very large, say 10 km, coriolis effects would be minimal and the whole experience could be made very comfortable. People intending to return to Earth could spend much of their time in the 'train', working out in gymnasiums, eating, sleeping, relaxing etc., all in a 1g environment. In addition to ensuring they remained perfectly capable of returning home at the end of their tour of duty, they would be possessed of relatively superhuman strength for their duties out on the surface during the working day.
If the number of temporary workers from Earth were to rise, with an ever-enlarging colony, the number of carriages on the loop could be increased to accommodate them. In fact, there's nothing to prevent the whole rail being taken up with carriages, carrying hundreds of people, assuming you can streamline the process of getting everyone in of an evening and out again in the morning! This problem would be obviated if the rail were built underground, just inside the perimeter of a large dome, in which case the carriages wouldn't have to be pressurised and getting in and out would be very much simpler and quicker.

Oops! Sorry Ian. Looks like I started waffling on again!

Ian Flint · 2004-07-18 08:12:36

Shaun,
Thanks for the Trig lesson.

By the way, the train idea is nice -- but boring. If the train looses power, it will just come to a nice easy stop with the floor angle adjusting itself automatically. Its much funner to have a flattened cone-shaped city spinning on a cushion of air. When there is a power failure it comes to a screeching halt throwing everyone to the floor, and then the occupants have this annoying tilted floor to deal with.

dicktice · 2004-07-18 13:05:33

Waffle away, Shaun: The train idea for g-conditioning is brilliant--on Mars or Moon. Now, if I could only get someone to do a critique on the g-simulator turntable idea, for body condition research on Earth--before we set out. . . ?

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#26 2004-07-09 15:27:06

Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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Re: Low gravities and colonization. A show stopper? - Any suggestions apart from exercising?

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