Artificial Gravity Habitats

[Atlas2342]

As you may know, microgravity presents all sorts of problems, whether health or practical. What are some of the ways we can achieve artificial-grav habitats and are they feasible in the near-future?

[Nibb31]

Do we really need another thread on the subject?

 

[p1t1o]

Barring pseudo-science and actually using mass, what other way is there than spinning? 

There's constant acceleration in a straight line too I suppose, but I'm guessing thats not really in-scope.

Building a spinning habitat I would think is technically feasible today, apart from the massive financial/political/societal hurdles.

 

[K^2]

50 minutes ago, p1t1o said:

Barring pseudo-science and actually using mass, what other way is there than spinning?

Displacement current Hall effect gravitoelectromagnetic coils. With equipment I can feasibly assemble, I was estimating artificial gravity on the order of 10^-27 m/s². With expensive laboratory-grade equipment, I might be able to get 3, even 4 orders of magnitude on top of that. Which is still many orders of magnitude weaker than gravitational field of a grain of sand. I couldn't even come up with a way to measure a field that weak.

But, you know, technically artificial gravity from a solid state device. If we could figure out how to build a gravitoelectromagnetic equivalent of a transformer, we'd be set.

As far as practical ways go, though, you need to be constantly accelerating without going anywhere on average. That's basically definition of spinning.

[magnemoe]

Spinning is easy to do if craft is designed for it like an mars ship. 
For ISS the purpose is micro gravity. 

For an future station having one spinning an one non spinning module makes some sense. 

[Atlas2342]

As for how to rotate the habs, rotating servos or electromagnets, perhaps?

[p1t1o]

You should read Ringworld, it will blow your mind

[Atlas2342]

Written by Niven? right?

[Bill Phil]

Magnetic bearings...?

[p1t1o]

Yup, Niven.

[fredinno]

9 hours ago, K^2 said:

Displacement current Hall effect gravitoelectromagnetic coils. With equipment I can feasibly assemble, I was estimating artificial gravity on the order of 10^-27 m/s². With expensive laboratory-grade equipment, I might be able to get 3, even 4 orders of magnitude on top of that. Which is still many orders of magnitude weaker than gravitational field of a grain of sand. I couldn't even come up with a way to measure a field that weak.

But, you know, technically artificial gravity from a solid state device. If we could figure out how to build a gravitoelectromagnetic equivalent of a transformer, we'd be set.

As far as practical ways go, though, you need to be constantly accelerating without going anywhere on average. That's basically definition of spinning.

Magnetogravity would be WAY more of a pain than just spinning.

8 hours ago, magnemoe said:

Spinning is easy to do if craft is designed for it like an mars ship. 
For ISS the purpose is micro gravity. 

For an future station having one spinning an one non spinning module makes some sense. 

..."relatively" easy.

7 hours ago, Atlas2342 said:

As for how to rotate the habs, rotating servos or electromagnets, perhaps?

Motors. You know, the same way we operate these on Earth.

[tater]

Rotate the whole thing and make the docking craft match, as per the Pan Am spaceplane docking in 2001

[magnemoe]

1 hour ago, fredinno said:

Magnetogravity would be WAY more of a pain than just spinning.

..."relatively" easy.

Motors. You know, the same way we operate these on Earth.

Easy compared to an Mars mission. you can spin the entire ship as you will not dock anything with it or do more than perhaps rsc adjustment during cruise. 

[cubinator]

44 minutes ago, magnemoe said:

Easy compared to an Mars mission. you can spin the entire ship as you will not dock anything with it or do more than perhaps rsc adjustment during cruise. 

A wide, cylindrical ship might also not need ullage motors if the fuel is stuck to the outside wall of the tank. One could have feeds to the engines placed on the side angled "downwards". These could feed fuel to the engines in a rather simple manner once the ship was set spinning.

I think the best design for a Mars ship would either be a cylindrical design that spins the whole way, or a non-spinning ship with a large inflatable hab where astronauts can run around in circles to exercise. This option might be a slightly simpler and cheaper one because the different parts do not have to go through heavy stresses from the gyroscopic action. However, the astronauts would still have to spend a lot of time exercising, which detracts from time they could spend doing SCIENCE!!! The fully-spinning option also has it's drawbacks, in that it would either have to de-spin for docking/undocking or have a way to dock while spinning, in which case the astronauts will need a way to blast No Time For Caution while doing so. And also lots of design problems because it's hard to maneuver while spinning. It also would likely precess, being essentially a giant gyroscope, so that would need to be accounted for when maneuvering, or if the ship has continuous thrust.

[K^2]

3 hours ago, fredinno said:

Magnetogravity would be WAY more of a pain than just spinning.

Magnetogravity has nothing to do with it. Gravitoelectromagnetism does. Completely different concepts. And artificial gravity via gravitoelectromagnetic effects would work exactly the way you see in sci-fi movies. If it could be amplified to 1g ranges.

[p1t1o]

10 hours ago, K^2 said:

If it could be amplified to 1g ranges.

From your earlier comment on the subject, I get the feeling that this might take a sun's worth of power input.

 

But at least it would be handy to dry our clothes

[Atlas2342]

A scaled-down O' Neill cylinder could work instead of a rotating habitat....

[Bill Phil]

14 hours ago, K^2 said:

Magnetogravity has nothing to do with it. Gravitoelectromagnetism does. Completely different concepts. And artificial gravity via gravitoelectromagnetic effects would work exactly the way you see in sci-fi movies. If it could be amplified to 1g ranges.

Wait: wouldn't that require an environment where gravity and electromagnetism are merged? Like a certain temperature range, if I recall correctly...

[PB666]

42 minutes ago, Bill Phil said:

Wait: wouldn't that require an environment where gravity and electromagnetism are merged? Like a certain temperature range, if I recall correctly...

de Sitter precessional / Einstein-Lense-Thirring differential . Not sure at all how it fits into this discussion, to observe you have to be observing an inertial reference frame around a massive object, its the difference between the expected and observed motion.

 

[tater]

2 hours ago, Atlas2342 said:

A scaled-down O' Neill cylinder could work instead of a rotating habitat....

That still rotates, it's just bigger (any given XX meter wide cross-sectional slice is a torus, basically).

[Bill Phil]

47 minutes ago, PB666 said:

de Sitter precessional / Einstein-Lense-Thirring differential . Not sure at all how it fits into this discussion, to observe you have to be observing an inertial reference frame around a massive object, its the difference between the expected and observed motion.

 

I'm referring to the four forces having been combined in the early universe, and that they eventually differentiated as the universe cooled. I forgot the order, though. I'm pretty sure that gravity and electromagnetism were the last to split.

[PB666]

56 minutes ago, Bill Phil said:

I'm referring to the four forces having been combined in the early universe, and that they eventually differentiated as the universe cooled. I forgot the order, though. I'm pretty sure that gravity and electromagnetism were the last to split.

The unified forces are represented by quantum gravity or as to say the higgs field is resolving, as the energy density falls in quantum version of space-time (which is to say complete chaos; neither measures of space or time have meaning), relativistic space-time appears along with the unified three remaining forces with space-time comes gravity, BUT there are questions about its meaning because there is a cogent argument to be made gravity is a quantum response to the spread of energy density. Since, during unification,  energy is not that spread out theerfore gravity may not have been that meaningful. In addition, there is no rest mass, and apparently the amount of energy in the universe is changing (or somehow converting from quantum state(s) to other quantum state(s) or is simply an unstable constant). Another problem of declaring the existence of gravity is that the quantum state of the universe at this very early transition is not clear at all, quantum mechanics states that objects can shift around in space and time without paying the energy cost, so if the universe is represented by a single or few quantum states, even if space time is resolving. If you tried to actually measure the warping of space your hypothetical ruler would end up in a thousand different values at once. The universe has to get to a point where there are sufficient enough quanta around that their relationships stabilized space-time. But even this does not work well temperature and space-time both have problems, because both require inertial reference frames and that implies mass, which does not exist, theoretically gravity exists, but until mass shows up temperature and gravity are rather meaningless. Again I should state that gravity only appears to us to be constant, I repeat appears, in the laboratory it cannot be measured to the level of other constants, and some speculate that the gravitation constant wavers and fluctuates. Gravity is the measure of how space-time warps in response to energy most notably rest mass but it does not respond to all energy equally. The more the effort is made to get rid of all sources of extraneous energy, the more the constant appears to vary. We can add to this uncertainties regarding dark matter and energy. lol. My opinion is that the force of gravity resolves not at once but slowly, the resolution of the quantum singularity starts the process but until mass appears and remains its not constant. Somewhat arbitrary but since some models have energy pouring into the universe creating a barrage of unstable exotic material . . . . . .I should state the standard disclaimer, there are no observable universe before CMBR, and it is unclear whether or how quantum gravity exists.

Edited February 10, 2016 by PB666

[fredinno]

19 hours ago, cubinator said:

A wide, cylindrical ship might also not need ullage motors if the fuel is stuck to the outside wall of the tank. One could have feeds to the engines placed on the side angled "downwards". These could feed fuel to the engines in a rather simple manner once the ship was set spinning.

I think the best design for a Mars ship would either be a cylindrical design that spins the whole way, or a non-spinning ship with a large inflatable hab where astronauts can run around in circles to exercise. This option might be a slightly simpler and cheaper one because the different parts do not have to go through heavy stresses from the gyroscopic action. However, the astronauts would still have to spend a lot of time exercising, which detracts from time they could spend doing SCIENCE!!! The fully-spinning option also has it's drawbacks, in that it would either have to de-spin for docking/undocking or have a way to dock while spinning, in which case the astronauts will need a way to blast No Time For Caution while doing so. And also lots of design problems because it's hard to maneuver while spinning. It also would likely precess, being essentially a giant gyroscope, so that would need to be accounted for when maneuvering, or if the ship has continuous thrust.

A wide, cylindrical ship is too big for the first Mars mission, it might be worth it to carry 100 people, though.

[cubinator]

3 minutes ago, fredinno said:

A wide, cylindrical ship is too big for the first Mars mission, it might be worth it to carry 100 people, though.

That's probably what will happen. The first small missions will probably use non-rotating inflatables. The wide spinning ship is probably 2100s material.

[K^2]

5 hours ago, Bill Phil said:

Wait: wouldn't that require an environment where gravity and electromagnetism are merged? Like a certain temperature range, if I recall correctly...

Gravitoelectromagnetism has nothing to do with electromagnetism besides the name and similar looking equations. It is just a linear approximation to GR. Device I've suggested is electromagnetic, but coupling between forces is via a shared charge. Specifically, electromagnetic field has stress-energy, which is the gravitational charge.