Gravity in the Elysium Space Station

Posted: May 7, 2013 at 7:46 am

I dont know too much about the upcoming moving Elysium, but it looks pretty cool. Here is the trailer. The first interesting thing I saw was the rotating space station.

Why are you weightless in space? I have already answered this question in great detail. The short answer is that you dont really feel gravity anyway since it acts on all parts of your body equally and on the space station. Both the space station and all parts of your body have the same acceleration which means there is no interaction forces between them. What you actually feel is not the gravitational force, but rather the force that other objects push on you. On the surface of the Earth, you are mostly at rest. This means that the ground has to push up on you to balance the gravitational force and you feel weight.

Ok, Im not going to spend more time talking about weightlessness. If you arent happy with my short answer, read my other post. For now, lets say that you have a person in a space station. The space station could be in orbit around the Earth or in deep space where there are no strong gravitational forces. Either way, the person will be weightless.

How do you make a person feel weight? One way is to accelerate the person so that there is a force from the ground of the space station that is similar to Earth. Here is a force diagram of a person on the surface of the Earth and a person in the space station with fake gravity.

The person on the ground has the two forces that are equal in magnitude (thus no acceleration). I am calling FN the normal force. This is the force the person feels and calls weight. Now, we want the astronaut person to have this same FN force. Since there is no gravitational force, this one force would make the person accelerate in that same direction.

That is our fake gravity force make the person accelerate. There are two ways this person could accelerate in that direction. The person could increase in speed in that direction, this would be an acceleration. However, this would also change the velocity. For a station in orbit, this wouldnt work but it would be fine for a spaceship traveling to another star and accelerating. No, for the space station we need to do something else. The answer is to make the acceleration perpendicular to the velocity of the person so that the person moves in a circle.

When an object moves in a circle, the velocity vector is always changing and the direction of this change in velocity is towards the center of the circle. Acceleration is the rate of change of the velocity vector. Its really that simple. Here is how this would work.

And this is your basic spinning space station. You have seen this in countless space movies because it is an idea that would actually work. How do you change the acceleration of the object moving in a circle? There are two things to change, the radius of the circle and the speed that you move in a circle. The magnitude of this acceleration is:

See the article here:
Gravity in the Elysium Space Station

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