The Concept of Artificial Gravity for the Spaceship

Why Do We Need Gravity?

The role of gravity is much more than just preventing us from floating, it helps the human body to grow and develop. It makes the muscles and bones work hard, keeping them intact. It keeps our body functions running.

Effects of Zero Gravity

Without gravity, there would be no use of the muscles, so the muscles can lose mass very quickly. Muscle mass can vanish at a rate as high as 5% a week. It also affects bones, 'Bones in space atrophy at a rate of about 1% a month.

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Moreover it affects your circulatory system. In earth, gravity causes blood pressure to be higher in our feet than in our brain, without gravity, blood moves towards the brain down the pressure gradient, making blood pressure too high in our head, this causes the brain to think there is too much blood in our body so 'within two to three days of weightlessness, astronauts can lose as much as 22 percent of their blood volume.

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" As there is a huge amount of blood less, then your heart doesn't need to pump as hard. It's going to atrophy.'

Of course, humans can adapt to growing in low gravity, if they plan on staying in space forever, however it will be difficult for us to return back to earth, taking up to 1 month or more to get used to the strong gravitational pull. Though it is unlikely that our inhabitants will return back to earth, we will need to make sure our settlement has gravity, or something similar to it, to make sure our body doesn't wear away and more importantly, to ensure proper development of the bones and muscles of children living in our settlement.

How Will We Create Artificial Gravity?

There are currently multiple proposals:

Linear Acceleration

The principle behind linear acceleration is: 'If we could produce enough constant acceleration in a straight line, the crew would be 'pinned' to the ship in the opposite direction of travel.

'This solution is highly effective in accordance with Newton's Third Law for short travel times. However, our spaceship will not be using this because we will be rotating around the earth in a circle to ensure easy trade between our spaceship so linear acceleration would be impossible.

Magnetism

Using the concept of diamagnetism, it is possible to create the effect of gravity. Unfortunately, this requires magnets with extremely strong magnetic fields and so far, experiments have only been able to levitate a mouse. It requires either expensive cryogenics or several megawatts of power. RotationThis solution is basically rotating the entire spaceship to create artificial gravity. This is the most efficient and likely solution. The concept of centripetal force will be used.

Concept behind Artificial Gravity

We will rotate the central sphere. Rotating the sphere will mean it is moving in a circular path, and a centripetal force is required to do that. "A centripetal force is a net force that acts on an object to keep it moving along a circular path." The centripetal force is provided by the exterior of the spaceship, so the force acting on an object is the push of the exterior, pushing on the object. According to Newton's second law, "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force" so the centripetal acceleration is equal to the value of artificially created gravity.

To calculate the centripetal acceleration, the formula a=w2*r is used, where w is the angular velocity r – the rotation radius. The centripetal acceleration should be 9.8 - 10 ms-2

To calculate the angular velocity, the formula is rearranged to: w=(a/r)1/2 radians/second

However, to calculate rotations per minute, another formula is used:

Rpm = w /((2π)/60)

This is because 1 rotation is 2π and 60 seconds = 1 min

Number of rotation needed to give 1 g in the smaller spheres:

Assuming centripetal acceleration is 9.6 ms-2 Radius from the axis of rotation to the center of sphere= 8750mw= (9.6/8750)1/2F w = 0.03312314684843300245421408950212π/60 = 0.10471975511965977461542144610932Rpm = 0.0331.../0.1047…

Rpm = 0.31630275310121081077668589881917

The bigger sphere needs to rotate ≈ 0.316 times per minute.To calculate the value of gravity in the bigger sphere:

formula - (rpm*(2π/60))2 * r Rpm = 0.31630275310121081077668589881917 r = 2.52π/60 = 0.10471975511965977461542144610932(0.316…*0.104…)2 =a = 0.0331231468484330024542140895021≈ 0.033 ms-2

Thanks to the very low gravity in the central sphere, it will be possible to carry out major constructions with ease.

Problems with Pseudo-Gravity

If the radius of a spaceship is too small, it would causing a significant difference between gravity felt at the head and gravity felt a the feet, making movement tricky. Fortunately, due to the large radius of our spaceship, these side effects will be minimised.

Moreover, "the angular velocity of the habitat should be significantly higher than the relative velocities with which an astronaut will change position within it." To compare the angular velocity and speed of the human body, the angular velocity is converted to linear velocity, using the formula r*w where R is the radius, W is the angular velocity.

The linear velocity will be 1043.3807308953 km/hr. A human's maximum speed is 45 km/hr, so the angular velocity is still much higher."

'The Coriolis effect gives a force that acts at right angles to the motion and the rotation axis and tends to curve the motion in the opposite sense to the habitat's spin." Moving towards or away from the axis of rotation can cause a force, pushing the person towards or away from the direction of rotation. These forces can make a person nauseous. However, our spaceship has less than 1 rpm, the effects of Coriolis effect is greatly reduced.