large structures generating artifical gravity

[cz77]

Aside from the difficulty in building a large enough structure to spin and create (via centrifigul force) an artificial gravity for a vehicle to go to the outer planets, are there any known health risks from doing so?
What would be the minimum diameter for something to spin that would be gravity beneficial and human useable?
Years ago, I thought I read that as an example, the Discovery crew habitat in 2001 would not be functional as the diameter wasnt large enough to offset some inner ear problems.

[eeergo]

There's a nice article in Wikipedia (I confronted it with other sources some months ago, though right now I can't recall them) that talks about 224m-diameter spacecraft to produce 1g of equivalent centrifugal acceleration. http://en.wikipedia.org/wiki/Artificial_gravity You have to take into consideration that centrifugal acceleration (and therefore force) is a function of the distance to the center of spin, the radius of the hypothetical spacecraft, so if you have a small radius in comparison with a person's height, you'd have a big acceleration gradient between that person's head and his feet. It's easy to do the calculations considering a=w^2*R, being w the rotational speed. This 'a' would be our g-force, so the 'weight' of any part of the body could be calculated: W=m*a (W=weight)

Also you have to take into account the Coriolis effects, which can turn any simple task into a nightmare if they're strong enough, and can mess up quite badly with any human equilibrium system. Wikipedia's article talks about a 2rpm maximum rotational speed.

[sandrot]

Enjoy past posts! Particularly the thread on AG facility in ISS vicinity explores the bad effects of Coriolis force.

http://www.nasaspaceflight.com/forum/forums/thread-view.asp?tid=5666&start=1

http://www.nasaspaceflight.com/forum/forums/thread-view.asp?tid=6628&start=1

[drbobguy]

What most people usually forget is you *DON'T* need a large structure.  All you need is a tether connecting two "pods", or a "living pod" and a counterweight.  The tether could easily be a couple kilometers long.  If you had one living space "pod", a counterweight, and a tether connecting the two you could get nearly perfect artificial gravity (certainly a human couldn't tell the difference).  The counterweight need not even be that heavy if the tether is long, because the two will rotate about their center of gravity, so if the tether is really long, even if the counterweight is 1/10 the mass of the pod as long as the tether is long the rotation rate will still be pretty low.

[cz77]

Well that was my question..in order to eliminate or move to a minimum the coriolis effect, how large do we need to go in order to create a beneficial amount of gravity for a crew?  I am wondering more about a centrifuge structure attached to a non spinning section than the use of a tether.

[khallow]

I remember someone discussing a smallish centrifuge (say no more than a few meters in diameter that you could sleep in.

[sandrot]

That was me?!?

see the thread:
http://www.nasaspaceflight.com/forum/forums/thread-view.asp?tid=6628&start=1

particularly here:

Jim - 19/2/2007  11:58 AM

sandrot - 19/2/2007  11:11 AM

I quickly read the paper, there is the formula for calculating the centripetal acceleration given radius and angular rate. A 2m radius cylinder should spin at 12 rpm to have 1/3 g and 20 rpm to have almost 1 g... am I correct? Would it make sense to use the centrifuge as sleeping quarters for the astronauts?

Too small, Corolis effect would effect the crew

The referenced paper with the formulas was:
http://www.artificial-gravity.com/JANNAF-2005-Sorensen.pdf

[spacedreams]

khallow - 11/4/2007 11:11 AM I remember someone discussing a smallish centrifuge (say no more than a few meters in diameter that you could sleep in.

There is a NASA sponsored centrifuge down in Galveston, TX at UTMB that they have been using for long duration studies.

[publiusr]

drbobguy - 10/4/2007  7:44 PM

What most people usually forget is you *DON'T* need a large structure.  All you need is a tether connecting two "pods"...

And pray the tether doesn't break? I'll take my HLLVs and a substantial structure.

[Jim]

publiusr - 23/4/2007  7:28 PM

drbobguy - 10/4/2007  7:44 PM

What most people usually forget is you *DON'T* need a large structure.  All you need is a tether connecting two "pods"...

And pray the tether doesn't break? I'll take my HLLVs and a substantial structure.

An HLLV blowing up is more likely than the tether breaking

[publiusr]

They have an atmo to stop meteors--and with bad luck being what it is...with the bare foot being the one to find a tack, one meteor nip and there the tether goes.

 On a substantial structure--spackle. Big deal.

[Jorge]

publiusr - 23/4/2007  6:46 PM

They have an atmo to stop meteors--and with bad luck being what it is...with the bare foot being the one to find a tack, one meteor nip and there the tether goes.

Wrong. There are fault-tolerant tether designs out there. Google "Hoytether" for one.
--
JRF

[lewarren]

I worked on this study, and am somewhat knowledgeable on the topic.

Experiments in rotating rooms and centrifuges have been conducted with consideration of the coriolis effect.  Humans are quite capable of adapting to rotation, though there is a threshold.

A rotating space vehicle that produces constant gravitational force or an on-board centrifuge that produces intermittent gravity is a very effective and viable solution to interplanetary travel.

lewarren

[cz77]

On an engineering level, what is the minimum size, to eliminate as a human factor, the coriolis effect?

[joema]

cz77 - 24/4/2007  1:09 PM
On an engineering level, what is the minimum size, to eliminate as a human factor, the coriolis effect?

The earlier artificial gravity studies indicate a 1500 meter cable-based system rotating at 1 rpm and producing about 1/3 G would be free of any significant Coriolis/dizziness artifacts. Extensive data on this here: http://www.spacefuture.com/archive/artificial_gravity_and_the_architecture_of_orbital_habitats.shtml

Alternately, you can achieve 1G using 2 rpm and a 223 meter tether: http://library.thinkquest.org/C003763/index.php?page=adapt06. Biomedical studies show few people have problems at 2 rpm.

In general anybody can tolerate 1 rpm, almost anybody 2 rpm, most people 3 rpm, and it drops off from there.

Some newer research indicates properly conditioned people can adapt to significantly higher angular velocities than previously thought: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11020210&dopt=Abstract

[JulesVerneATV]

recreate gravity at levels many times stronger than on Earth

also used in Titanium aluminide, development of TiAl based alloys, it also links to exo planet science astro biology, has implications on the feasibility of existence of exobacteria

There was also rodent studies, finding that rats exposed to slightly increased gravity are able to adapt with little chronic stress but at a higher level of basal metabolic expenditure increased 'rate of living'.

its capable of generating 300 times Earth's gravity for a load up to 20 tonnes

China Focus: China debuts world's mightiest centrifuge, unleashing ultra-intense gravity
http://www.chinaview.cn/20250929/4cb96f960bca44ff9cd1911203ed4be6/c.html

world's mightiest centrifuge
https://www.globaltimes.cn/page/202509/1344827.shtml


Human time-tolerance: acceleration
https://archive.fo/wzx1R


A Large Diameter Centrifuge (LDC) has been developed by ESA allowing the acquisition of measurement points in the range from 1 to 20 g. This instrument can provide a hypergravity environment for cells, plants and small animals, as well as physical science and technological experiments. The LDC is part of the Life and Physical Sciences Instrumentation and Life Support Laboratory (LIS) at ESTEC (the Netherlands), dedicated to serve the science and technology user communities throughout Europe.
https://www.esa.int/Education/Spin_Your_Thesis/The_Large_Diameter_Centrifuge