Can We Create Artificial Gravity?

one of the biggest problems we face when traveling in space is the atrophy our bodies endure oil in microgravity the astronauts on the International Space Station have to exercise several times a day to maintain their bone and muscle strength but is there an alternative can we create artificial gravity I'm sure you've seen the idea before in movies like 2001 a Space Odyssey where the entire space station spins to create artificial gravity the people inside can now walk comfortably just like they do on earth it does this by exploiting centrifugal force now it seems that whenever someone mentions centrifugal force angry mobs will show up in the comments section declaring it isn't real which just isn't the case let's see why NASA developed this huge centrifuge to test the possibility of simulated gravity back in the 1960s here we are looking from an inertial frame of reference that just means we're looking from an outside perspective and we can clearly see that there is no force pulling the sky outwards it is just as inertia carrying him forward and the floor he is walking on provides the centripetal force to prevent him from flying off what happens if our reference frame moves with the astronaut this is called a rotating reference frame or a non inertial reference frame to him the rest of the world is moving and he is standing stationary in this reference frame centrifugal force is absolutely a real and measurable force pushing him downwards just like gravity the only thing that is fictitious is his perception of what is causing it this occurs because in physics and engineering we must balance forces the system has to be in equilibrium Newton's third law states for every action there's an equal and opposite reaction so centripetal force exists in this reference frame there has to be a force pushing em outwards that is centrifugal force and the moment the rotation stops it vanishes again so if this works so well why haven't we seen a spinning Space Station yet well one problem is size to make this practical we need a massive ship which would be incredibly expensive to get into orbit the acceleration your body will experience is directly proportional to the speed and radius of the space station we can calculate the gravity Space Station V from 2001 a Space Odyssey would generate with some pretty simple math the Space Station V had a diameter of 300 meters and sponsz access once ever 60-seconds that would put its gravity at about the same as the moon's for java gravity similar to Earth's it would need to spin once every 24 seconds if we were to make this a realistic size let's say the same as the International Space Station it would need to spin once every 10 seconds this would probably be pretty disorientating just ask Sandra Bullock another problem we face on smaller stations like this is the gradient and acceleration you would experience because the acceleration is directly proportional to the distance to the rotational Center your head will experience less artificial gravity than your feet this would force the blood to your feet just like when you spin a bucket of water around this effect diminishes with larger stations so to make a practical space station with artificial gravity the station would have to be huge which is simply too expensive besides the ISS is most valuable to us as a laboratory to test the effects of microgravity what if money was not an issue what would it take to get a space station like Elysium built for the mega-rich as an escape from the turmoil on earth into orbit Elysium dwarfs space station v measuring in at 60 kilometers wide and it is estimated to weigh about a million metric tons spacex can currently launch a kilogram into space for about 2700 dollars with their Falcon 9 rocket this will be reduced to one thousand six hundred and fifty dollars per kilo when they launched their Falcon 9 heavy variant at the end of the year but it would take over 18,000 launches to bring the 1 million metric tons to low Earth orbit that's one point six five trillion dollars to just get the materials of Elysium into space with current technologies then we have to worry about the cost of materials and engineering that would go into building something with this magnitude that is far more difficult to calculate but we can take some clues from the ISS it is estimated to have cost about 150 billion in total it took 36 shuttle flights that'll cost a 1.4 billion each to bring the materials into space that's a total cost of fifty point four billion dollars so the launch costs were just 33 percent of the total cost a conservative estimate for the cost of Elysium could put it up five trillion dollars that's sixty two point three buildings but there are half a million people onboard Elysium so if the costs were split between everyone that would be about 10 million each that isn't so far-fetched and the price of space travel is destined to reduce in future we do have material strong enough to build a like this the forces on Elysium would be similar to the ISS other than the additional stress created by centripetal and centrifugal force it's interesting to note that the designers of Elysium took note of this the stress in spinning structures like this would decrease as you move away from the rotational center this means it would need a stronger structure the closer you get to the center this clearly influenced their design with these tapering spokes but we run into some problems when a realized sir isn't enough aluminium in the world to build this thing it would take at least ten years worth of the world's total aluminium production just to build the structure this would cause a huge surge in the cost of materiel an alternative method could be sourcing the materials from space this could reduce the launch cost and there is plenty of metallic material available on the moon and near-earth asteroids so this technology is definitely possible our only barriers are launch costs and material availability something on the scale of Space Station V would be easily achievable who knows maybe we'll be traveling to space as tourists in the near future once again thanks for watching I look a bonus for you at the end of this outro you can skip ahead or wait to watch it I'd like to thank my patreon supporters bastion Nick and FG for helping me to revise this video your support is really appreciated thank you if you'd like to see more content or support real engineering the links from my patreon Instagram Facebook and Twitter accounts are below so I promise to include this in my last video but I couldn't figure out a way to include it in this video in a seamless way the centrifugal governor was used in the industrial revolution to control the amount of steam entering the steam piston which was essential as supply and demand can vary with fuel and load for example if the engineer puts more coal into the boiler the pressure will rise and these masses will spin faster which increases the centrifugal force and pushes them outwards this raises this leave up which in turn closes the valve to reduce the amount of steam entering the engine so the centrifugal governor acts as a sensor to provide direct mechanical feedback to control the speed of the engine it is one of my favorite inventions of the Industrial Revolution thanks for watching till the end everyone hope you liked the video and feel free to ask me any questions on Twitter

Channel: Real Engineering

Views: 3,063,640

Rating: 4.8946981 out of 5

Keywords: artificial gravity, centrifugal force, centripetal force, space, international space station, NASA, ESA, spacex, elon musk, engineering, physics

Id: im-JM0f_J7s

Length: 6min 33sec (393 seconds)

Published: Wed Jun 29 2016

Reddit Comments

[u/TaytoCrisps]

Hey, I made this video. Thanks for posting this. Just saw it pop up on my feed. Wasn't expecting to see it here, since /r/engineering is a bit more of a serious subreddit.

[u/Nate4846]

When people claim centrifugal force "isn't real" they're correct in a way. It isn't a literal force. Centrifugal force is an "apparent force" that acts outward when a body is rotating around some axis. This is caused by the bodies inertia, your forward motion, and a centripetal force perpendicular to your forward motion (pointing to the center of your rotation)

ELI5: when you rotate, nothing pushes you outward. There is a force accelerating you inward making you feel like you're being pushed outward

Example: when you go around a right turn in a car you feel like something pushes you left because you slide left in the car. In reality, you're staying still and the car is moving right and also starts pushing you to the right

This is better explained with relative motion but I tried to keep it eli5 level

[u/jpowell180]

"Space Station V" is pronounced "Space Station Five".

Because, you know, Roman Numerals.

FTFY :)

[u/[deleted]]

This isn't actually answering the question whether we can create artificial gravity. Which we can't yet, because it's based on physical laws that we still don't fully understand. It just states that we can create what would feel like gravity by utilizing known physical laws.

It's a cool video and pretty interesting nevertheless!

[u/thru_dangers_untold]

It's funny when people talk about the raw materials available in asteroids and assume space based manufacturing is an easy thing. They to gloss right over the processes involved in creating a finished product from such a raw starting point. 3D printing is a good start, but there are limits that need serious pushing.

[u/[deleted]]

Easier just to build a widget that creates and modulates a black hole at the center of the circular space station.

[u/fjdkf]

No mention of tethers? Throw a 2km rope between two vessels and spin. Cheap and relatively easy artificial gravity for long manned trips around the solar system.