Could we make artificial gravity?

July 31, 2015 by Fraser Cain, Universe Today
Astronauts strut their superpowers on the final shuttle mission, STS-135. Credit: NASA

It's a staple of scifi, and a requirement if we're going to travel long-term in space. Will we ever develop artificial gravity?

It's safe to say we've spent a significant amount of our lives consuming science fiction.

Berks, videos, movies and games.

Science fiction is great for the imagination, it's rich in iron and calcium, and takes us to places we could never visit. It also helps us understand and predict what might happen in the future: tablet computers, cloning, telecommunication satellites, Skype, magic slidey doors, and razors with 5 blades.

These are just some of the predictions science fiction has made which have come true.

Then there are a whole bunch of predictions that have yet to happen, but still might, Fun things like the climate change apocalypse, regular robot apocalypse, the giant robot apocalypse, the alien invasion apocalypse, the apocalypse apocalypse, comet apocalypse, and the great Brawndo famine of 2506.

Not to mention things that'll probably never happen, things that could not be, in accordance with the laws of nature. Faster-than-light travel, instantaneous teleportation, and the ability to destroy whole planets with a space station laser pointer.

But there's one future technology, a massive violation of the laws of physics which plays a role in nearly every single book, show and movie you can mention.

I promise you, if authors, screenwriters and directors tried to adhere to the laws of physics with even a shred of accuracy, your favorite scifi would unfold very differently.

I'm talking artificial gravity.

It's magical. Captain Kirk can actually *stand* on the bridge of the USS Enterprise, and he just stands there. He can sit in the mess and enjoy a pint of Romulan Ale not served in a plastic bag, or go just to the bathroom without a freaky-weirdo suction toilet.

I understand scifi authors are imagineering spaceships like ocean going vessels, yet in space.

That's where they go wrong.

On Earth, you can stand on the deck of your warship, drink your Romulan Ale from an open topped non-collapsible container, and it's all thanks to you, gravity. The Earth is pulling the ale towards its center, and it's stopped by the glass, which is stopped by your meat and skeleton, stopped by your well polished boots, stopped by the plates on the deck of the ship, held up by the rest of a the ship, held up by buoyancy, which all work to keep everything from zipping down to the center of the planet, or at least the floor of the ocean.

Astronauts share a lunch on the ISS. Credit: NASA

Out in space, no gravity. You've seen the crew on board the International Space Station.

Once you're in microgravity, you float around like a balloon. You have to drink and pee into a tube, and one of those involves a vacuum cleaner. Protip: Do not mix up those tubes.

Most importantly, once a spaceship started moving, or undertook evasive maneuvers, everyone would ping pong around like crunchy meaty bingo balls.

Will we ever develop artificial gravity?

The only way to get gravity is with mass. The more mass, the more gravity you get. Without mass, you can't have gravity.

Before we go any further, there's no such thing as anti-gravity.

Now that's out of the way, there are a few ways we can fake it.

The force of gravity that we feel is actually just an acceleration towards the center of the Earth at 9.8 meters per second squared, or 1G.

As Einstein showed us, everything's relative. If you were in a spacecraft and it was accelerating away from Earth at a rate of 1G, it would feel exactly the same if you were standing on the ground.

This is known as constant acceleration, and if you could somehow power a spacecraft with that much energy, it would be just what you needed.

Want to get to the Moon? Accelerate at 1G for an hour and a half, turn around, and decelerate for the same amount of time. Not only would you get to the Moon in under 3 hours, but you would have experienced Earth gravity the entire time.

Want to fly to Jupiter? It would only take about 80 hours of acceleration, and then 80 hours of deceleration. At the halfway point of this journey, you're going more than 2,800 kilometers per second, which is close to 1% the speed of light.

Could we make artificial gravity?
Astronauts on the Moon. Image credit: NASA

Want to travel a light-year? Accelerate for about a year, then decelerate for a year. At the mid-point, you'll be going the speed of light.

Uh oh. There's the problem. As you probably know, as you approach the speed of light, it requires more and more energy. And you can't go faster than the speed of light. So using this method only lets you travel about a light year at a time.

There's an idea that I'm sure you Arthur C Clarke fans know, which requires way less energy: artificial gravity from centripetal force… spinning.

Take a large enough spacecraft and set it spinning.

Thanks to inertia, free floating objects within the spacecraft, like astronauts, would try to fly off into space, but the hull of the spaceship would keep them inside.

To make this comfortable, you need a ring-shaped spacecraft with a radius of 250 meters. This ring would need to turn about twice a minute for astronauts within the spacecraft to experience 1 G.

Interior of the Discovery, from 2001: A Space Odyssey. Credit; Metro-Goldwyn-Mayer

Building a spacecraft like this is an engineering challenge, but it's probably within reach of our current technology.

Something like this would help us explore the Solar System without the health risks of microgravity.

That's right, not only is microgravity super annoying for trying to pee, but it'll also ruin you.

Unless we discover anti-gravity, we'll probably never have the kind of artificial gravity we see in science fiction. It's going to be huge rotating rings for the foreseeable future, sadly.

What's your favorite science fiction story that seems to have ignored the problem of ? Tell us in the comments below.

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robert_inventor
not rated yet Jul 31, 2015
These numbers such as 250 meters and 2 rpm depend on what the human tolerance is for spinning in these conditions, and depends also on what level of gravity is optimal for human health. Both are currently unknown.

The optimal level of gravity could be anything between zero g (known to be harmful) and full g. We have no way of doing long term experiments of more than a few minutes at less than full g and more than zero g with humans.

As for the spin rate, all experiments on the Earth have full g along the axis of rotation (or else variable artificial g if the axis is horizontal) - or again last for only a few minutes.

Then volunteers are always experiencing hyper gravity.

Then also, for them, "down" is parallel to the spin axis. So coriolis effects affect horizontal motions (in space they act on vertical motions - you'll feel pushed sideways if you stand up or sit down rapidly but won't notice anything if you walk around in what feels like a horizontal plane to you. ..
robert_inventor
not rated yet Jul 31, 2015
Then, the spinning motions in Earth experiments affect a different part of the ear from spinning motions in space, which is more like the effects of sea sickness, a "rocking type" motion - spinning around an axis parallel to what you see as the horizontal plane. Or like tumbling sky divers.

Humans may be able to tolerate far higher spin motions in space, some experiments from Skylab suggested this. Or may be able to adapt to them. And what if, for instance, humans only need an hour or so, or even a few hours of gravity a day to stay fit? Maybe while eating meals, or while exercising - or else while asleep.

Rats don't get giddy or sick when they spin - and humans with defects in their vestibular system can tolerate fast spin rates with no effect. So they at least could tolerate a small centrifuge only a meter or two in diameter. Others also may be able to adapt.
robert_inventor
not rated yet Jul 31, 2015
So - just saying - that it's too early probably to design artificial g facilities. What we need right now are experiments in orbit, to find out what is the "gravity prescription" for human health, what the typical tolerance is for spin rates - and how easy it is to live and work in artificial gravity for different radii and spin rates. After that we can think about the design. Otherwise you can end up with a hugely expensive spaceship which is over engineered and not needed.

Many experiments we can do. Joe Carrol has an ingenious idea for a tether experiment we could do right away using the Soyuz and its final stage on any crew mission to the ISS with almost no extra fuel.
http://www.scienc...l-131278

And you could also do short arm centrifuges: http://www.scienc...g-131279

winthrom
not rated yet Jul 31, 2015
Suggest you try http://www.calcto...trifugal using Radius = 30 feet, Angular Speed = 10 RPM [or Linear Speed = 31.5 feet/sec], Mass = Weights of 100, 150, & 200 pounds. Results will be 1.02252 g [10 RPM] and 1.02800 g [31.6 feet/sec]. "g" is an approximation of gravity, while Centrifugal Force is "weight" in pound-feet, (experienced weight of gravity). A center elevator access from the "Bridge" that matches RPM speed would lead to quarters at about one earth gravity. The bridge will be weightless.

Alternatively, Gravity on the bridge works also: If the interior of the Enterprise bridge (conveniently shaped as a large disk) rotates internally, then the RPM goes down and the linear speed goes up. The bridge looks a bit different, but Capts. Kirk/Piccard can still sip ale/tea in the command chair. At a radius of 250 meters and 1.9 RPM, g = 1.00922 g. The command module will be on an edge, as will be crew quarters.
rderkis
1 / 5 (1) Jul 31, 2015
I wish these people that know so much about gravity would hurry up and explain dark matter. Seeing we only know it's there by its gravity. They are such experts about gravity, they can tell us what's possible and not possible with a straight face. These same people not long ago were telling us that dark matter is not possible.

Dark matter is estimated to constitute 84.5% of the total matter in the universe.
Bongstar420
not rated yet Jul 31, 2015
I wish these people that know so much about gravity would hurry up and explain dark matter. Seeing we only know it's there by its gravity. They are such experts about gravity, they can tell us what's possible and not possible with a straight face. These same people not long ago were telling us that dark matter is not possible.

Dark matter is estimated to constitute 84.5% of the total matter in the universe.


I suppose your better to say then

Finally, its not "antigravity" which we need to discover...its how to induce gravitic fields
grondilu
not rated yet Jul 31, 2015
"science-fiction is great for the imagination, it's rich in iron and calcium" Wait,... what?
EyeNStein
5 / 5 (2) Aug 01, 2015
Whoever wrote this article clearly doesn't have a clue about relativity.
As if the speed of light is like a magical speed limit where the brakes are suddenly applied.
Constant 1G acceleration is definitely the most useful artificial gravity for space travel over any distance; but there is no limit at one light year nor any other distance.
In orbit rotational centripetal gravity would be required, and inflatable rotating circular ships have been considered.
But at present microgravity is too useful on the ISS to throw it away just to make the crew comfortable.
Nik_2213
not rated yet Aug 01, 2015
There's a lot of fuss made about 'vestiblular issues' on a rotating craft. IIRC, the 'wall of death' stunt riders who go around & around on motor bikes in a 'silo' do self-select. They got their 'sea-legs', many candidates didn't...

Either way, the 2001 astronaut jogging to increase his apparent gravity reminds me of the Skylab crews bouncing around in their capacious tank...
KBK
not rated yet Aug 02, 2015
Anyway, it's the theory of relativity, not the law of relativity.

Real physics and real scientific research has no laws.

Laws are social constructs for punishing people for breaking averaged behavioral rules.

If we have any sort of law in physics, this would make physics a religion, built of dogma, where the physics pope issues papal bulls and kills people (burns them at the stake) for acts of discovery.

Think about that for a minute.

In fact, Relativity being a theory, means it is a stop gap measure, a placeholder, until something more fleshed out comes along, to replace it. Any true explorer of science knows that public science, at the atomic level (thus quantum - and thus ALL).... has not one clue abut the true nature of reality.

Any buttwipe calling it a law and arguing against proposed methods of going past it.... needs to be curb stomped, as they'd be living in the world of dogma and religion. They would deserve no place at the table of reason or science.
winthrom
not rated yet Aug 02, 2015
Since the Higgs Boson has been verified, there is an opportunity to discover how mass correlates to particles (from the quantum level up to the macro level that is integral with gravity) and to dark matter, which seems to have gravity without mass. We know that mass (via gravity) distorts space/time, but how? Apparently gravity can exist without mass?

The shadow of gravity falls heavily on the rate of time passage in space/time theories, so, in an accelerating expansion universe, where space gets ever greater between massive galaxies, what is happening to time in the space/time relationship? Could dark matter be a relationship between expansion speed/acceleration and creation of space? Is dark energy (the theorized cause of the measured expansion) related to black hole formation where accretion of mass into black holes turns space/time inside out and provides the energy for dark energy? After all, where does the mass in a dark hole singularity finally end up?
winthrom
not rated yet Aug 02, 2015
One might also ask: Since gravity causes stars to form and give off massive amounts of energy, where does all that energy go? What effects on space/time does the radiant energy of galaxies have?

In all thermodynamic relationships (that I know of) between different energy levels, energy flows from high concentration to low concentration. Gravity creates energy, and thus acts as a high level energy source. Energy of gravity is acquired from somewhere/time, where? We live in a universe where time "flows" ever forward. When gravity slows time to a stand-still (think black hole singularity) is the time frame of the black hole the same as the point in time where the black hole formed, or does it link to something/time else? We know that gravitational lenses cause space/time to warp so that light passes through a part of space time where time is slowed. We also know that light emerges from the lens resuming its' customary speed in our space/time frame, traveling a different distance.
Benni
1 / 5 (1) Aug 02, 2015
I wish these people that know so much about gravity would hurry up and explain dark matter. Seeing we only know it's there by its gravity. They are such experts about gravity, they can tell us what's possible and not possible with a straight face. These same people not long ago were telling us that dark matter is not possible.

Dark matter is estimated to constitute 84.5% of the total matter in the universe.

What's to "explain"? Do you imagine you're looking in a mirror and 84.5% of you is not there?

An expert has already had his say on the topic, Albert Einstein. He proved the exact angle of gravitational lensing as starlight passes by the visible disc of the Sun, and he didn't use an 84.5% fudge factor labeled dark matter to do it.
RealScience
5 / 5 (1) Aug 02, 2015
An expert has already had his say on the topic, Albert Einstein. He proved the exact angle of gravitational lensing as starlight passes by the visible disc of the Sun, and he didn't use an 84.5% fudge factor labeled dark matter to do it.


@Benni - Current theories on dark matter may or may not be correct (there's a Nobel waiting either way), but I haven't seen ANY dark matter theory claim that the sun (or that a person) is 84.5% dark matter.

But more importantly, Einstein based his prediction on the total mass of the sun, as determined by the sun's GRAVITATIONAL EFFECT on the planets, so IF the sun has dark matter in it then Einstein automatically included that dark matter it because dark matter would, if present, be part of the sun's total mass as measured by have a gravitational effect on the planets. Thus to make his calculation Einstein did not have to know care whether or not part of the sun's mass is dark matter.

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