Nanobots, Magnets, and Artificial Gravity

[SunJumper]

If there were tiny robots in your body, and they excerted a force on your body in the down direction (ie from your head to your feet), maybe from being magnetically attracted to the floor (or a magical fifth force), then could this work the same way as ordinary gravity or centripetal gravity, in terms of your biological systems (ie, would this prevent your bones from softening, etc). The purpose of this would be to prevent decay of the muscles and the bones, as there is little else to my knowledge that is as drastically affected by microgravity.

Would the required magnetism mess with the electrical components of the spacecraft? If so, would it be impractical to separate the sleeping and excercise modules from the rest of the spaceship and have those zones electronics free (except from the production of the electromagnetics and some regenerative electricity production in the excercise module).

Would it be cheaper or easier to use the nanobots to instead reinforce the bones and muscles of the astronaut and get around this mess?

[flightmaster]

Interesting question... It depends on what they were exerting the force on. If they were just in your bloodstream and pushing down I would think they'd end up at the bottom of a blood vessel. I dunno, I did terribly at biology in school.

[M5000]

Interesting question... It depends on what they were exerting the force on. If they were just in your bloodstream and pushing down I would think they'd end up at the bottom of a blood vessel. I dunno, I did terribly at biology in school.

I would think that if they were loose in your bloodstream, they'd simply all pool at the nearest point in your body to the magnetic source. To have simulated gravity, they would have to be attached somehow to, or integrated within your bones and muscle, so that you would basically "become" magnetic.

Aside from that, the concept is generally sound in theory.

Here's some other issues, though.

-The gravity would not be quite as strong, I don't think. I mean, it could be, theoretically, but it's just a magnetic field that large would require tons of power.

-Remember that magnetism's strength drops off much quicker than gravity, and builds up much quicker at close distances. Such a field would be very hard to control. Gravity is a much more gentle force than magnets at a close distance, and much more powerful at longer distances. Gravity is more "smooth", I guess I'm saying.

-Power requirements. I mean, like a LOT of power requirements...

-That magnetic field would most definitely mess with all kinds of stuff. The flux lines produced by that baby would be absolutely insane. It would be knocking out pretty much anything electrical, since you basically need to generate a continuous EMP for this idea to work.. So yeah this is pretty much the kill-all. You're literally EMPing yourself all the time if you want this kind of gravity.

Honestly, I don't think it would be cost or effort effective. It's a battle between sending up a workout gym or sending up a massive generator and somehow not EMP the entire station.

Buttttt.. If they were indeed attracted via a "magical fifth force", then yes I imagine this would work. Here's why...

Think about the particles that make up your bones and such.

They are attracted (as one effective object) toward the Earth during normal gravity, and the Earth is attracted to them.

All this would be doing is replacing the particles in your legs with nanobots, replacing the Earth with the force receptors used in the system, and replacing the force due to gravity with a magnetic or magical fifth force. This would still exert some sort of stress on your body that it needs to remain resilient. Maybe you could have the nanobots use some sort of control moment inside of them and basically try to "torque" you toward the "artificial gravity source." Or, maybe you could have teeny-tiny gyroscope type devices that resist movement inside of the astronauts' space suits, so that any movement would become slightly resisted by a force.

[georgexiro]

Actually, there would be no need for nanobots to simulate gravity. You could just build a centrifuge large enough and then with a little spin help you could recreate Earth-like gravity.Interesting question though.

[K^2]

Actually, there would be no need for nanobots to simulate gravity. You could just build a centrifuge large enough and then with a little spin help you could recreate Earth-like gravity.Interesting question though.

The main interest is in creating artificial gravity that points in consistent direction. Why? Because the higher acceleration you can achieve, the more efficient the launch can be. If you use magrail to launch from Moon, you can use shorter rail. You could shorten voyage distances. And don't get me started on what this can do for the military. Acceleration a pilot can withstand is one of the greatest limitations of modern jet fighters. It's part of the reason why un-manned anything is so much easier.

There are two principle problems with using magnetic fields. Yes, you can attach magnetic particles to every single cell. This will allow you to counter effects on flesh. Not having your internal organs crush themselves is definitely nice. But typically, the first problem of over-G is blood pooling in "lower" parts of the body. You'd have to replace blood with some sort of ferrofluid, and these tend to be too viscous to act as plasma.

Second problem is purely of mag-field permeability. Human body is filled with water. Water is a pretty strong diamagnetic. That means it actually provides some shielding from magnetic field. The effect is subtle at lower fields, but as the field strength gets higher, it becomes a serious problem. This is something you have to account for in MRI, and that's just 1-2 Tesla. So if you apply field strong enough to counter high acceleration, you'll actually be creating internal gradients that are causing problems.

Of course, if all you want is create an artificial 1G, then none of it really matters. Blood will circulate just fine in micro-G, so applying a magnetic force just to cells that make up the tissues will be sufficient to replicate almost all effects of gravity. But as it's been pointed out, a centrifuge works just fine for that. I don't think convenience of being able to apply 1G linearly will outweigh inconveniences of working with high mag fields. Then again, with everything moving towards polymer construction and superconductors in space being relatively "cheap" due to vacuum being a damn good insulator, maybe it can end up being easier.

Oh, by the way, you don't need nanobots for any of this. There are plenty of ways to bind magnetic particles to cell membranes.

but it's just a magnetic field that large would require tons of power.

Not if you use superconducting magnets. These only require power for cooling, and that can be minimized in space.

Edited April 21, 2013 by K^2