The Universe, who is fascinated by that?

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#1659395 27-Oct-2016 23:50

Rikkitic:

I honestly don't understand what you are going on about. Continuous centrifugal force has the same effect on the body as gravity. Fine, call it something else but the effect is the same and for this purpose that is what matters.

I think he means if you rotate something to cause centrifugal force, its hard to use. But, in space, you have mass, but there is weightlessness, so centrifugal has no force. There is no weight to create a force. Keep it simple. Use magnets to create weight. Lose the magnets to allow you to use the 360 degree space. In the ISS, there are four walls. Or four ceilings, or four floors. I feel magnets are the way to go. Easy and cheap.

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#1659462 28-Oct-2016 09:00

Magnets don't solve the health issues. Impossibly powerful ones might be able to simulate something resembling gravity, but apart from being impossible they would probably cause other health issues. Whether rotation creates a 'force' or not, and whether that force is centrifugal, centripetal, or something else, it does act as an effective gravity substitute and that was the basis of my question. If lack of gravity causes health problems, and spinning around and around solves that, why hasn't more work been done on this? It is a staple of science fiction stories back to the 1940s.

A related question might be just how much gravity/acceleration is necessary to maintain human health? Would half a G do it? Maybe a quarter? The less you can get away with, the easier it might be to construct a rotating cylinder for this purpose. As long as lack of gravity is a problem, I think these are useful questions.

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#1659482 28-Oct-2016 09:28

You can't use magnetism to simulate gravity.

A human body is largely unaffected by magnetism, while our muscles and skeletons have to constantly resist gravity.

Magnetism is only really useful for sticking to a surface.

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#1659527 28-Oct-2016 10:03

They have thought about it - I didn't come up with the idea of a long tether between say engines and fuel module, with a habitable module swinging around it. It seems very inelegant - but trying to achieve enough centrifugal force with a solid "donut" or "barbell" space station design, it'd have to be huge else would have to spin very fast. An added annoyance would be that the spin rate would change ever so slightly every time you shifted something, and it would wobble unless you kept it in perfect balance. Bigger would be better, but as a spacecraft (as opposed to a "station") getting something bigger to travel between planets etc is a big problem.

If there's a manned mission to Mars in the foreseeable future, IMO it's a near suicide mission anyway for the astronauts, the chances of there being some fatal failure in a mission of that duration must be very high, they're going to be blasted by radiation of a type that's very difficult to shield against and for which it appears the effects are much more systemic/severe than originally thought, cardiovascular disease, neurological effects/brain damage etc. For the time being, for bone density loss then I don't think they've got a better solution than careful exercise. But there's even a previously unforeseen problem with that, space blindness, apparently permanent physical changes to the eyes possibly attributable to increased intracranial pressure in microgravity, exacerbated by increase in blood pressure during the exercise needed to prevent the rest of you wasting away. Probably some other nasty effects to the brain I guess, if intracranial pressure is high enough to stuff your eyesight.

IMO, the human body needs an extensive redesign in order to endure extended space travel. I'm losing faith in the concept of manned missions to the planets unless/until those issues could be fully overcome. To me it just seems pointless and prohibitively expensive, when you could send machines that could see better, hear better, taste and smell better, feel better and do a whole lot of other stuff much better and more reliably than humans ever could. Send them off to do the exploring, if the "point" of exploring is to enable eventual colonisation of Mars etc, let the machines go and sort out all the problems humans would face, call us back when they've got the answers.

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#1659532 28-Oct-2016 10:12

Diamagnetic levitation is a well-known technique that does, in fact, simulate gravity. Here is a quote: "In the case of diamagnetic levitation, the gravitational force is compensated on the level of individual atoms and molecules. This is, in fact, as close as we can - probably ever - approach the science-fiction antigravity machine."

Because it acts on the smallest components of the body, it affects everything, muscle, organs, bone. My understanding is that it could be used just like gravity in a zero-g environment. The problem is the practical difficulty of generating the enormous magnetic field involved, which requires huge amounts of power and superconduction as well. Not very handy in space.

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#1659535 28-Oct-2016 10:18

Rikkitic:

Magnets don't solve the health issues. Impossibly powerful ones might be able to simulate something resembling gravity, but apart from being impossible they would probably cause other health issues. Whether rotation creates a 'force' or not, and whether that force is centrifugal, centripetal, or something else, it does act as an effective gravity substitute and that was the basis of my question. If lack of gravity causes health problems, and spinning around and around solves that, why hasn't more work been done on this? It is a staple of science fiction stories back to the 1940s.

A related question might be just how much gravity/acceleration is necessary to maintain human health? Would half a G do it? Maybe a quarter? The less you can get away with, the easier it might be to construct a rotating cylinder for this purpose. As long as lack of gravity is a problem, I think these are useful questions.

Magnets will cause the legs to get exercise so that's a start. The rest you will have to do yourself. Spinning round and round when you are weightless wont give a gravity effect

It wont add weight or force. Thats why nothing has been done about it.

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#1659538 28-Oct-2016 10:24

JWR:

You can't use magnetism to simulate gravity.

A human body is largely unaffected by magnetism, while our muscles and skeletons have to constantly resist gravity.

Magnetism is only really useful for sticking to a surface.

My point was magnetism in the form of wearing shoes that are being held to a floor will allow you to walk. The effort by the legs to overcome that magnetism will give welcome

exercise and use to the leg muscles. The rest of the body will need to be exercised by resistance exercises.

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#1659549 28-Oct-2016 10:34

tdgeek:

Spinning round and round when you are weightless wont give a gravity effect

It wont add weight or force. Thats why nothing has been done about it.

Sorry, that is wrong. Rotation in a zero-g environment does exactly that, it gives a gravity effect. Obviously spinning yourself won't do much good, but being inside a large spinning chamber that is rotating at the correct speed will definitely create a gravity effect. This is the basis of g-force fairground rides, those training centrifuges that pilots and astronauts spin around in, and rapidly rotating a bucket of water over your head without the water spilling out. All of that is centrifugal force at work.

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#1659550 28-Oct-2016 10:35

tdgeek:

JWR:

You can't use magnetism to simulate gravity.

A human body is largely unaffected by magnetism, while our muscles and skeletons have to constantly resist gravity.

Magnetism is only really useful for sticking to a surface.

My point was magnetism in the form of wearing shoes that are being held to a floor will allow you to walk. The effort by the legs to overcome that magnetism will give welcome

exercise and use to the leg muscles. The rest of the body will need to be exercised by resistance exercises.

I think you'd end up with big muscles needed to pluck ones legs up from the floor, but not so much the muscles you'd need for actual walking in gravity.

If the exercise isn't very carefully designed for a long duration space mission, then the astronaut would probably end up with all kinds of orthopaedic issues, from being continuously "pulled out of shape" in a similar manner to people suffering from partial paralysis.

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#1659569 28-Oct-2016 11:04

Rikkitic:

tdgeek:

Spinning round and round when you are weightless wont give a gravity effect

It wont add weight or force. Thats why nothing has been done about it.

Sorry, that is wrong. Rotation in a zero-g environment does exactly that, it gives a gravity effect. Obviously spinning yourself won't do much good, but being inside a large spinning chamber that is rotating at the correct speed will definitely create a gravity effect. This is the basis of g-force fairground rides, those training centrifuges that pilots and astronauts spin around in, and rapidly rotating a bucket of water over your head without the water spilling out. All of that is centrifugal force at work.

I agree what I have bolded. But in space, there is no weight. A G Force of 2G doubles your weight. In space there is no weight to double

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#1659572 28-Oct-2016 11:06

Hang on, think about it a bit more.

You are weightless in the donut shaped ring that you want to start spinning. Because you are weightless you are touching nothing within the donut shaped ring but floating"free".

Now spin the ring. What happens?

you remain weightless and the ring spins with you still suspended in weightlessness. You probably remain in one place as the ring goes around.

If mass has no weight then no force is created by spinning it or being in it while it spins, that's why they call it scienceFICTION!

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#1659578 28-Oct-2016 11:16

Seakiwi:

Hang on, think about it a bit more.

You are weightless in the donut shaped ring that you want to start spinning. Because you are weightless you are touching nothing within the donut shaped ring but floating"free".

Now spin the ring. What happens?

you remain weightless and the ring spins with you still suspended in weightlessness. You probably remain in one place as the ring goes around.

If mass has no weight then no force is created by spinning it or being in it while it spins, that's why they call it scienceFICTION!

Yep. If I held onto the outer edge, I will feel a sideways force until I catch up with the speed of the outer edge. If the spinning was always accelerating, I would always feel a force, but the force is sideways. Now, space exploits is very very old. Over 50 years old. We have sent devices almost everywhere is our solar system. A spinnng spacecraft whether it be Apollo, or ISS, would allow us to have simulated gravity. But it never happened.

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#1659588 28-Oct-2016 11:31

Listen guys, you really do have this wrong. Look it up. You are not 'weightless' in space at all. Your weight at orbital height where the ISS is, remains almost the same as on the surface of the earth. The reason you feel weightless is because of that centrifugal force everyone keeps saying doesn't exist. According to Wikipedia You are orbiting around the earth at a velocity of about 7.79 km/s at an altitude of 200 kms. It is the centrifugal force of this orbital rotation that cancels the effect of gravity. If you could hold yourself in place at the same altitude without orbiting, you would weigh close to the same as you normally do. If you could fly to the moon in a straight line, as the characters did in Jules Verne's novel, your weight would gradually decrease to zero when you reached the point where the moon's gravity balanced the earth's gravity, and would then gradually increase again as the moon's gravity took over.

It is true that if you were stationary (relative) inside an orbiting rotating ring, you would be weightless in spite of the ring's rotation. But what gives you weight is the fact that you are not stationary, but are rotating with the ring. You are spinning around in a circle and this causes you to accelerate outwards until the surface of the ring stops your progress. The effect is simulated gravity. Honest.

You can test this on a carousal at a children's playground. The faster it spins, the greater the force pulling you outward. This works just as well in orbit as on the surface of the earth. I don't know any other way to explain this more clearly.

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#1659624 28-Oct-2016 11:41

If you won't take my word for this, here is a Wikipedia entry that explains it. If that still doesn't convince you, I will be happy to post other, even more authoritative links. The Internet is full of them. This is a well-established scientific principle.

https://en.wikipedia.org/wiki/Artificial_gravity

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#1659632 28-Oct-2016 11:52

Rikkitic:

Listen guys, you really do have this wrong. Look it up. You are not 'weightless' in space at all. Your weight at orbital height where the ISS is, remains almost the same as on the surface of the earth. The reason you feel weightless is because of that centrifugal force everyone keeps saying doesn't exist. According to Wikipedia You are orbiting around the earth at a velocity of about 7.79 km/s at an altitude of 200 kms. It is the centrifugal force of this orbital rotation that cancels the effect of gravity. If you could hold yourself in place at the same altitude without orbiting, you would weigh close to the same as you normally do. If you could fly to the moon in a straight line, as the characters did in Jules Verne's novel, your weight would gradually decrease to zero when you reached the point where the moon's gravity balanced the earth's gravity, and would then gradually increase again as the moon's gravity took over.

It is true that if you were stationary (relative) inside an orbiting rotating ring, you would be weightless in spite of the ring's rotation. But what gives you weight is the fact that you are not stationary, but are rotating with the ring. You are spinning around in a circle and this causes you to accelerate outwards until the surface of the ring stops your progress. The effect is simulated gravity. Honest.

You can test this on a carousal at a children's playground. The faster it spins, the greater the force pulling you outward. This works just as well in orbit as on the surface of the earth. I don't know any other way to explain this more clearly.

In orbit is different. We are falling to the earth. We have mass and weight due to Earths gravity. However, we dont deploy a means to add a gravity effect. Why is that? When we are not orbiting, perhaps going to Mars, we wont do that either.

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