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I had an idea of a chamber that an astronaut would use when they would sleep that would allow their body to experience a gravity-like force to negate the negative effects of weightlessness, (Bone or muscle loss)

Crude drawing of the chamber

The magnets would be just above the person, the magnetic field of the magnets would be directed by a metamaterial in a way which resembles the depiction above. the chamber would be close to a 90 degree angle relative to the floor to allow the repulsion to simulate standing up and that the distance between the closest point and farthest point of the occupant to the magnetic field to be minimal. How feasible is concept to negate the negative effects of weightlessness. And are there any ways to improve the design.

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  • $\begingroup$ Gravity or any artificial alternative (even the very clever one you've proposed) would make restful sleep at such a steep angle difficult. Unless otherwise constrained, the sleeper would tend to slide downwards. Try sleeping on a 15-20 degree body length memory foam wedge to get an initial baseline for what a steeper angle might be like. $\endgroup$ Jun 6, 2022 at 13:13
  • $\begingroup$ There would be constraints and a ledge where the occupant would put their feet on. This chamber wasn't designed with comfort first. In my setting, this chamber would be commonly used on military vessels in which case a rotating centrifuge would be a vulnerable target since they would be close to the outside of the ship, shielding the centrifuge would add extra weight, and would make the ship a bigger target. This chamber would allow the crew quarters to be placed deep inside the ship, perhaps near the powerful magnets, like the magnets create the ships protective magnetic field. $\endgroup$ Jun 6, 2022 at 13:46
  • $\begingroup$ Wouldn't continuous exposure to such a strong magnetic field cause ... deleterious effects? Genuinely curious $\endgroup$
    – BMF
    Jun 8, 2022 at 12:24
  • $\begingroup$ Perhaps, I have heard some where that powerful magnetic fields might cause vision problems or affect the heart. Although in the other hand, frogs and various other animals that experienced diamagnetic levitation did not suffer from any ill side-effects. $\endgroup$ Jun 8, 2022 at 12:55

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It would probably take a lot of energy. The researcher levitated frogs with this effect and it took 16 Teslas, they showed the maths which I will put here.

Whether an object will or will not levitate in a magnetic field B is defined by the balance between the magnetic force F = M∇B and gravity mg = ρV g where ρ is the material density, V is the volume and g = 9.8m/s2. The magnetic moment M = (χ/ µ0)VB so that F = (χ/µ0)BV∇B = (χ/2µ0)V∇B2. Therefore, the vertical field gradient ∇B2 required for levitation has to be larger than 2µ0ρg/χ. Molecular susceptibilities χ are typically 10-5 for diamagnetics and 10-3 for paramagnetic materials and, since ρ is most often a few g/cm3, their magnetic levitation requires field gradients ~1000 and 10 T2/m, respectively. Taking l = 10cm as a typical size of high-field magnets and ∇B2 ~ B2/l as an estimate, we find that fields of the order of 1 and 10T are sufficient to cause levitation of para- and diamagnetics. This result should not come as a surprise because, as we know, magnetic fields of less than 0.1T can levitate a superconductor (χ= -1) and, from the formulas above, the magnetic force increases as B2.

In summary, to produce enough force you will essentially need 10 Teslas. This is not enough to levitate something but if we get the force to equal gravitational attraction and then point it down it will be like gravity acting on the person. I am not sure how much power this will draw however if the spaceship had a nuclear reactor on board or other handwavium device I'm sure this could be a viable method.

Or you could just use the energy to spin a centrifuge.

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  • $\begingroup$ Ships in my setting use powerful magnets to shield from radiation and accelerate propellant, this was another way that the magnets are used for that I thought of. $\endgroup$ Jun 6, 2022 at 5:22
  • $\begingroup$ Well then if you have already found a way to power these magnets or have really powerful natural magnets in your universe I would say that this could totally work. $\endgroup$ Jun 6, 2022 at 5:24
  • $\begingroup$ A link to the original work, if you please. $\endgroup$ Jun 6, 2022 at 14:06
  • $\begingroup$ @JustinThymetheSecond here you go: ru.nl/hfml/research/levitation-explained/diamagnetic-levitation $\endgroup$ Jun 7, 2022 at 0:15
  • $\begingroup$ That article unfortunately appears to be undated. But it did confirm that the 10 Tesla figure was for Earth's gravity. To get less than Earth's gravity would require less. On the Moon, levitation would be much easier. Inertia would be the same, however. Getting it up would be hard, keeping it up not so much. $\endgroup$ Jun 7, 2022 at 14:22
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The basic idea of simulating gravity while the crew sleeps is fundamentally flawed: bed rest is used to simulate the effects of freefall even under a full gravity here on Earth's surface. The main effect of resting in a magnet chamber while strapped to the wall would be to add the effects of sleep deprivation on top of everything else.

What you want is to simulate gravity during exercise. Diamagnetic repulsion might be somewhat helpful with this...as long as you don't need to carry any ferromagnetic objects or electronic devices. Accidentally doing so could be rapidly fatal, as could any failure of the structures supporting the magnets, which would be under extreme forces. And don't even go near that end of the ship if you have a pacemaker or other implant.

Really, it'd at best only be an incremental benefit over exercise in microgravity (which has been shown to be reasonably effective on the ISS), has a lot of potential for odd side effects and catastrophic accidents, and would unavoidably complicate the design of the ship and add huge mass and power penalties.

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  • $\begingroup$ May you explain why it only might be somewhat helpful? $\endgroup$ Jun 8, 2022 at 7:06
  • $\begingroup$ @spaceamoeba1010 As I said, exercise in microgravity is reasonably effective. At best this would provide results somewhere between that and exercising in centrifugal or actual gravity. $\endgroup$ Jun 8, 2022 at 11:36

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