How Fast Should a Space Station Rotate?

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kentagions
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How Fast Should a Space Station Rotate?

Postby kentagions » Wed Jan 09, 2019 10:42 am

In Soft Science Fiction, artificial gravity is produced by gravity plates and repulsor or attractor fields. Sometimes, the author doesn't mention it at all, leaving the reader to wonder what fantastic mechanism keeps characters on the floor. Soft Scifi, or Fantasy in space, doesn't need to adhere to real-world science, it just needs to be consistent. Really.

Hard Scifi, however, needs to adhere to Physical Laws as they exist in our universe. Long-term habitation of a space station requires artificial gravity due to the serious detrimental effects of microgravity on the human body. The only way to generate artificial gravity is with centrifugal force, something done on carnival rides for a hundred years. Easy, right?

The three parameters needed are Radius (From rotational center), Angular Velocity (Period of Rotation in RPM) and Centripetal Acceleration (The force - in gravities - at the perimeter). Gravity equals Radius times (two pi over Angular Velocity) squared. Angular Velocity equals two pi times the square root of Radius over Centripetal Acceleration (Where Centripetal Acceleration is greater than zero). Basically, the bigger the radius of a spinning ship (or space station), the slower it has to rotate to produce one gravity at the habitation level. Easy peasy.

Or go here: https://www.artificial-gravity.com/sw/SpinCalc/

Don't put the calculations in your writing because it will limit your audience. Definitely, know how fast your space structure is rotating so you get a feel for the setting, how it looks from outside looking in and inside looking out. If it's spinning too slow, basketball games will be amazing. If it's spinning too fast, your characters will be really short.

Best of luck,
Kent

amoskalik
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Re: How Fast Should a Space Station Rotate?

Postby amoskalik » Thu Jan 10, 2019 5:42 am

Very cool. Thanks Kent!
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johnprater
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Re: How Fast Should a Space Station Rotate?

Postby johnprater » Thu Jan 24, 2019 1:05 am

kentagions wrote:In Soft Science Fiction, artificial gravity is produced by gravity plates and repulsor or attractor fields. Sometimes, the author doesn't mention it at all, leaving the reader to wonder what fantastic mechanism keeps characters on the floor. Soft Scifi, or Fantasy in space, doesn't need to adhere to real-world science, it just needs to be consistent. Really.

Hard Scifi, however, needs to adhere to Physical Laws as they exist in our universe. Long-term habitation of a space station requires artificial gravity due to the serious detrimental effects of microgravity on the human body. The only way to generate artificial gravity is with centrifugal force, something done on carnival rides for a hundred years. Easy, right? I had a project back at the university where I needed to write a thesis to it about physics. My teacher suggested using this source https://edubirdie.com/thesis-writing-help if I wanted to deepen my knowledge of physics and to write a good thesis. After some time I was amazed by how many things I have learned and how I used them to write a thesis. But let's continue with some parameters.

The three parameters needed are Radius (From rotational center), Angular Velocity (Period of Rotation in RPM) and Centripetal Acceleration (The force - in gravities - at the perimeter). Gravity equals Radius times (two pi over Angular Velocity) squared. Angular Velocity equals two pi times the square root of Radius over Centripetal Acceleration (Where Centripetal Acceleration is greater than zero). Basically, the bigger the radius of a spinning ship (or space station), the slower it has to rotate to produce one gravity at the habitation level. Easy peasy.

Or go here: https://www.artificial-gravity.com/sw/SpinCalc/

Don't put the calculations in your writing because it will limit your audience. Definitely, know how fast your space structure is rotating so you get a feel for the setting, how it looks from outside looking in and inside looking out. If it's spinning too slow, basketball games will be amazing. If it's spinning too fast, your characters will be really short.

Best of luck,
Kent

This is very exciting. I was always adored by such writings, and I enjoy reading such things about Science and other stuff. Sometimes, I regret that I didn't learn well physics and mathematics because it's complicated for me to understand such things. However, I always find it interesting to read such facts about physics and space and this kind of stuff.
Last edited by johnprater on Thu Jan 31, 2019 5:12 am, edited 2 times in total.

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morganb
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Re: How Fast Should a Space Station Rotate?

Postby morganb » Thu Jan 24, 2019 4:50 am

The other aspect to consider is that artificial gravity has become such a trope in science fiction that you probably don't need to explain it at all. Whenever I read a story that has people walking around inside starships or moons or asteroid bases, I just assume there's some sort of machinery to generate the field, and then I move on without a second thought.

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storysinger
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Re: How Fast Should a Space Station Rotate?

Postby storysinger » Thu Jan 24, 2019 11:50 am

Now that's a really good question. Picture three rings, the middle ring is set at earth-normal. The inner ring would spin slightly faster therefore gravity would exert a little more pull. If you wanted a more intense workout you'd be there. The outer ring would be easier on the physique so it would be better for rest and recreation. wotf015
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kentagions
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Re: How Fast Should a Space Station Rotate?

Postby kentagions » Thu Jan 24, 2019 2:21 pm

Hi storysinger,
Thank you for your interest. A correction, if I may.

Assuming that all rings have the same rate of revolution (RPM), the longest radius will always have the highest gravity. The outer ring is where you'll get the "intense workout."

Interestingly, this is one reason why rocket launch sites are located as close to the equator as a country can get them, and why they launch to the east. Centrifugal force (throwing an object away from the center of rotation) is greatest at the equator. The extra speed in Florida lowers the amount of fuel required for launch. The average human would weigh half a pound less at the equator as opposed to the poles. It isn't a big difference but when boosting heavy payloads, it adds up.

Have fun,
Kent

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orbivillein
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Re: How Fast Should a Space Station Rotate?

Postby orbivillein » Thu Jan 24, 2019 5:17 pm

A thought about artificial gravity, of whatever type, does life require tidal flux for metabolism triggers, from ebb flushes and flood inflows? Extant real-world ebb and flood cycles, of course, follow lunar and solar tide cycles, lunar more so. Sagan noted some degree of variable tidal force might be necessary for life to evolve, from perhaps a "Goldilocks" mass moon.

Single cell life was/is more or less static, and ebbs and floods diluted and carry/carried away wastes and carry/carried in nutrients. If humans are made of an untold number of single cell organisms and need tidal flux to regulate metabolism . . .

What if . . . humans travel beyond cislunar space for extended episodes and realize low or no gravity fluxes compromise cellular metabolism and health?

If the idea above is used by anyone else, acknowledge, please.

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orbivillein
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Re: How Fast Should a Space Station Rotate?

Postby orbivillein » Tue Jan 29, 2019 2:33 pm

kentagions wrote:In Soft Science Fiction, artificial gravity is produced by gravity plates and repulsor or attractor fields. Sometimes, the author doesn't mention it at all, leaving the reader to wonder what fantastic mechanism keeps characters on the floor. Soft Scifi, or Fantasy in space, doesn't need to adhere to real-world science, it just needs to be consistent.

Science type distinguishes soft and hard science fiction, respectively, social sciences and physical sciences. Fiction wants social facets anyway, includes science fiction, regardless of whether physical sciences or otherwise. Fantastic science and technology included, like non-rotational artificial gravity, are fantasy science fiction, where, like revenant and magic fantasy, impossible matters transpire.

kentagions
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Re: How Fast Should a Space Station Rotate?

Postby kentagions » Tue Jan 29, 2019 10:06 pm

Hi, orbivillein,

Thank you for the critique.

This space has been edited because I made a mistake out of ignorance (See above). This space was previously devoted to defending that mistake. I've made the retraction out of deference to orbivillein's greater knowledge (which is proven in the following post).

Best of luck,
Kent
Last edited by kentagions on Wed Jan 30, 2019 5:50 am, edited 1 time in total.

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orbivillein
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Re: How Fast Should a Space Station Rotate?

Postby orbivillein » Tue Jan 29, 2019 10:44 pm

The general science fiction culture consensus only distinguishes by science type, not by fantasy or otherwise real-world or fantastic science and technology "enabling devices", like faster-than-light spaceship drives: "Hard Science Fiction" Wikipedia; among many others, reader, writer, critic, reviewer, publisher, editor, not least of which Carl Sagan and John Campbell.

George Orwell's Nineteen Eighty-Four, for example, is "fantastic" soft science fiction, or was and isn't fantastic anymore, maybe, is rigorously about tyrannical and megalomaniacal government overreach, and weights fantastic social sciences features (political science at least) more so than fantastic physical, or natural, sciences, if any, anymore.

Being both and more a student of the several sciences and genre categorizations as well, though the taxa are slippery, the ease of comparison and contrast between hard and soft science fiction and physical and social sciences is fitting.
Last edited by orbivillein on Tue Jan 29, 2019 10:57 pm, edited 1 time in total.

kentagions
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Re: How Fast Should a Space Station Rotate?

Postby kentagions » Tue Jan 29, 2019 10:56 pm

Thanks again,

Call me educated.

Good luck,
Kent


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