Why don't we have artificial gravity in space?

"Designing a station with artificial gravity would undoubtedly be a daunting task. Space agencies would have to re-examine many reliable technologies under the light of the new forces these tools would have to endure. Space flight would have to take several steps back before moving forward again." -Andy Weir

Ever wonder, in those science fiction shows, how space travelers always stay “down” on their starship? Irrespective of acceleration, and despite the fact that the astronauts we have in orbit around Earth are weightless, they’re always depicted as having a floor and a ceiling that are well-defined, and always find themselves on the floor. This is physically impossible given the laws of physics as we know them today, but one small discovery could suddenly render artificial gravity possible.

This launch of the space shuttle Columbia in 1992 shows that acceleration isn't just instantaneous for a rocket, but occurs over a long period of time spanning many minutes. For a starship, versus a rocket, the acceleration would be many times greater, even if sustained, than a human body could withstand. Image credit: NASA.


We’ve measured the inertial mass of every particle and antiparticle we know of, and everything has positive mass/energy to it. But gravitational mass has only been measured for the particles, never for the antiparticles. There’s currently an experiment underway, the ALPHA experiment at CERN, whose goal is to measure which way antiparticles fall in a gravitational field. If they fall “down,” then they’re not the solution to artificial gravity. But if they fall “up,” this fictional technology could suddenly become real.

The possibility of having artificial gravity is tantalizing, but it is predicated on the existence of negative gravitational mass. Antimatter may be that mass, but we don't yet know, experimentally. Image credit: Rolf Landua / CERN.


We presently don’t have artificial gravity in space because there’s no such thing as a negative gravitational mass. But if we get an experimental surprise, all of that could change overnight!


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The only practical solution the problem of artificial gravity (that doesn't revolve around imaginary particles) has I think already been invented. We use them in medical labs. A modified swinging bucket centrifuge, as this would pretty much solve the gravity issue in multiple situations of acceleration and in orbit.
Solution One: The space station in orbit, A rotating area of the station or ship provides the artificial gravity (The big station in 2001 or the Discovery), but this has problems if the ship is accelerating, you would not be able to walk on the 'floor' since you would also be pushed to one side as well by the acceleration.
Solution Two: The ship or station is accelerating and as long as it does so, the artificial gravity due to acceleration keeps people on the floor, but the ship has to be designed with floors that keep the occupants feet towards the thrusters, and their heads towards the front of the ship, like a vertical skyscraper basically (thinking of the Chrysler Building with a rocket on the bottom comes to mind in my imagination), this is great until the ship has to start decelerating or goes into orbit where the crew will once again have to deal with weightlessness.
Combined solution:
When the ship is accelerating, the spinning parts of the ship or station stop spinning, the habitat modules are like the pivoting bucket test tubes in the centrifuge, they can pivot so that while under acceleration (when the centrifuge is turned off or not spinning), down is towards the thrusters, and the module pivots accordingly so like the test tube holding the sample at rest, it is in a position to take advantage of the acceleration as gravity. When the ship enters orbit, the spinning section starts up and the habitat modules pivot again, this time with their tops pointing towards the center of rotation, like the centrifuge spinning, holding the contents in the tubes.
The drawbacks to such a system of course is the spinning and pivoting mechanisms necessary to allow such movements, and then the engineering issues of allowing passage from such areas to other parts of the ship/station in various situations. The other major issue is balance. Even a small car tire can become a real issue if it isn't balanced. A very large ship/station would have even more trouble if it went out of balance, for one, it would wobble all over the place, or even tear itself apart. To prevent this from happening, a system to rebalance mass would be necessary. A science fiction book I read as a child proposed that water could be piped to different parts of the station into ballast tanks as necessary under careful computer guidance to keep everything balanced when things were moving about the interior of the station, this might actually be a workable solution to the balance problem.

If gravity was in space outside of earth. Then no one could afford to go to another Planet. As is if one built a Rocket ship for transporting people. Then each can run full power, then down to slow & you'd be traveling in high speed where ever. Also to talk to alien's. You must learn outside languages. Human's are Alien's even from 23 years from Earth. NASA'S Hubble Telescope while tracking an Alien Mother Ship later & I proved this to be true. Human's of different colors, cultures & languages. Also Alien's visit earth. I once received 2 question's from Alien's on Yahoo.com Answer's & answered them, but was later taken off Verizon's web site, because I'm the only expert from earth that knows the cause of Global Warming & what they look like. Global Warming has been off since May 2017 & the invaders now live on earth. Mike

By Michael J. Schmitz (not verified) on 19 Oct 2017 #permalink

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By Michael J. Schmitz (not verified) on 19 Oct 2017 #permalink

Even if anti-matter produces anti-grav, you would need a heck of a lot of it to get 1G. How much mass is needed to create 1G (depends on density, at the average density of about 5 the mass of the earth is needed. Denser matter, and you could get by with less. But, its a huge amount no matter how you do it, and presumably it is also inertial mass, which kind of makes spacecraft difficult to accelerate.

By Omega Centauri (not verified) on 19 Oct 2017 #permalink

All gravity responsive forms are made so by the predominating stabilizing force of what is termed 'antigravity' that is equally as 'transparent' as the more familiar form of gravitation'. Factors so derived are also mostly largely
and essentially beyond human grasp. Even so, lingering evidences of such a factual inscrutably predominating presence, remains as ever, inviolably vast.

What I find funny about fictional artificial gravity is when they are experiencing an emergency. All life support is shut down, but they still have gravity.

By Douglas Robertson (not verified) on 20 Oct 2017 #permalink

@Douglas Robertson,

I also wondered why they felt cutting life support would give themselves enough additional energy to power their shields or warp drives as well. Besides the fact they had spacesuits they could have put on, life support can be powered by actual mundane batteries on board space craft TODAY, while magic warp drives, energy weapons, and shields would take many magnitudes (more than nuclear explosions worth) more power than any form of energy production we presently have in existence. This would be the equivalent of claiming you could propel the titanic if you just transferred power from your cell phone to the engines.
Particles with imaginary properties make for very bad science, it's like discussing 'unobtanium' with a straight face. I'll wait for observation and evidence before getting excited.

@Alby and Michael J. Schmitz,
Neither of your random word generators are very good.
You can both do better than watchout4snakes.
Try harder.

@CFT #7:
I always thought the same but now it occurred to me:
Isn't it possible they count artificial gravity as part of life support for some reason? :-)

CFT #7
"Particles with imaginary properties make for very bad science, it’s like discussing ‘unobtanium’ with a straight face. I’ll wait for observation and evidence before getting excited."

That was good for chuckle. Dry humor.

By Michael Mooney (not verified) on 20 Oct 2017 #permalink

@Frank #9,
Oh Drat. I hate to say this but, If what happened to the Klingons on their own battle cruiser is any indication after their gravity generator was taken out (ST: The Undiscovered Country), then sadly you are correct. The space men are absolutely helpless aboard their own ships without gravity. I would have thought they would have been trained for this, or given magnetic inserts in their shoes (just in case). This just makes me think of sailors who can't swim. None of their ships are designed in any way for zero g, I don't ever notice hand holds or extra padding on their corridors or rooms...strange considering how often they get banged around from (fill in the blank) of the week. Of course...I also just considered, Sulu even tapping the gas pedal while the inertial dampeners and gravity generators were down would turn everyone onboard into a nasty wine stain on the nearest stern wall...so much for a drink. I've lost my appetite.

@CFT #11: Regarding the inertial dampeners (isn't that just lovely technobabble?), Michael Okuda used a slightly different phrase than you in the ST:TNG Technical Manual, "chunky salsa."

On a positive note, it can be good to know that the folks actually writing the shows recognize when they're short-circuiting known science.

By Michael Kelsey (not verified) on 20 Oct 2017 #permalink

We now know gravity is a wave. Yay. We have created other waves, sound, electromagnetic, light, wave pool at the park. As of now I don’t think we understand what creates gravity waves. If we do perhaps we will be able to create “gravity” with out exotic paticles.

@CFT #11:
Also consider the comfort level of life in space currently (always have to eat special space food for example).

Imagine how much that comfort level would increase if we could provide artificial gravity in space.

Or think about how uncomfortable a trip of months to Mars would be today versus if we could provide artificial gravity on the way. I think then a trip to Mars would become similar to taking a very long trip in a motor home or a cruise ship.

Gravity is really a basic need of human life.

@Frank #14,
I can agree about the need for artificial gravity if you are going to be space travelling for very long, but I think it would be best to address the problem with something along the lines of what we could actually do (as I suggested with a swinging bucket centrifuge type design), than holding out for someone to invent flubber.
I remember well watching Babylon 5 (They had a LOT of spinning kinds of ships and stations!!), when the Minbari promised to teach humanity how to make artificial gravity without spinning, allowing them to accelerate and maneuver more quickly (precession might have been a problem for them)...how every human's eyes lit up with excitement. Yes It would be cool, but right now the only place such things can exist is in our gravity defying imagination, not our science.

This is a tad off topic, but I am presently playing a game called 'Space Engineers'. It allows you to build all manner of space craft (or ground vehicles) that follow some of the laws of physics and mechanical engineering (you can add mods that add such things as more realistic thruster physics and aerodynamics in atmosphere), and uses sandbox voxels so you can watch anything you build crash, collide, burn up on re-entry, be torn in half, etc. It did become very clear to me early on that navigating the inside of space ship in zero g is a pain in the ass, so YES, I do just plonk down a handy artificial gravity generator so I can walk my engineer about. If you attempt to move about a space ship in zero g when it moves about or is hit by something, you learn first hand what a pinball feels like (it's very disorienting).
Some people have built working near full scale replicas of star ships from Star Trek, Star Wars, and other television and movies.
This won't solve the problems of anti-gravity, but it will maybe assuage your inner starship craving self that wants to fly by the seat of their pants in a craft of your own creation, or just see if you can navigate an asteroid field better than Han Solo.

All this discussion about"if we only had artificial grav, spacetravel would be so much nicer...
Do we need anything like 1G. Other than for conditioning out bodies, we could probably get by with .01 to .1G. Again spinning a spacecraft could do this, but the strength varies linearly with distance from the axis. Of course the psuedo grav field changes
direction as well as strength as one moves about. Might make for some interesting new ball games, where figuring out how to throw a ball to someone else would be mind-challenging.

By Omega Centauri (not verified) on 21 Oct 2017 #permalink

@Frank #17,
That was why I proposed a swing bucket centrifuge. When the craft was under acceleration, it would not spin, the habitat modules (where the test tubes would be in such a centrifuge) could pivot in such a way that they could take advantage of the acceleration, and when the ship got into orbit around Mars, it could then start to spin, the buckets would pivot be able to take advantage of the centrifugal force at that point.
See where the test tubes are?, imagine that was on a much larger scale where your habitat modules would be. Under g, the buckets are vertical to the direction of gravity, when not under thrust, they could spin, the bottoms of the buckets would swing outwards to provide the correct orientation to take advantage of the rotation for artificial gravity.
I only suggest this so the craft could have some way to provide gravity under thrust or not.

@Omega Centauri #18,
If you did spin for your artificial g, you wouldn't want your outermost level at any higher than one g, and everything above it (relatively to the axis) would be experiencing something lighter than 1g. I think you would need higher than the fraction of g you mention or human bones start to suffer bone density loss and muscles atrophy to the point the astronauts would be severely weakened by the time they reached their destination (Mars??). I think you might be able to take advantage of the lighter gravity in the inner levels for sleeping, I think I might have read somewhere that sleep in zero g has benefits.

“Particles with imaginary properties make for very bad science, it’s like discussing ‘unobtanium’ with a straight face. I’ll wait for observation and evidence before getting excited.”

Alchemy was essentially imagined chemistry making base metals into gold until not found. Missing elements in the periodic table had imaginary properties until found. Larger nuclei fall apart quickly, even faster as they get larger, but it is theorized that if even bigger at some point they will be stable again - should we try masker them?. The ether was imaginary until, well, yes, found to be imaginary. Historically the vacuum was imagined and considered by many an abstract concept devoid of reality. Radiowaves were theorized by Maxwells equations and later produced by Hertz. The Bohr model of atoms was first imagined and greeted with disbelief. Antimatter (first proposed whimsically) had imaginary properties, then Dirac theorized antielectrons, which a few years later were found (and up to antihelium now made). Theory says antiparticles are particles traveling BACKWARDS in time - how imaginarily silly is that? The neutrino (first named jokingly) was thought so removed from reality that Nature rejected Fermis first theoretical paper on them (really, a particle that can pass several times through the earth before hitting anything - preposterous!). The Higgs boson had imaginary properties till it was found. The graviton hasn't been found yet. Tachyons have imagined properties and haven't been found, but despite that folks still look for them - wasting their time?. The strings in string theory are still imaginary. Virtual particles were imagined and we only imagine they exist because we see their effects - never seen them directly (and apparently never will). Dark matter and dark energy have imaginary properties - don't even know what it is yet - but apparently its there - maybe its not there - should we stop looking for it? The list goes on.
My favorite, obvious why:- Transparent aluminum was imaginary until it was made.

" I’ll wait for observation and evidence before getting excited"
Yea, but where you gonna look? Imagination and theory tell us what to look for, and how, and I am excited about that. Makes for great science.

BTW Unobtanium was a term initially used by scientists and engineers for decades not as a joke, but to describe a material that was difficult or costly to make.
"Later, unobtainium became an engineering term for practical materials that really exist, but are difficult to get.[4] For example, during the development of the SR-71 Blackbird spy plane, Lockheed engineers at the "Skunk Works" under Clarence "Kelly" Johnson used unobtainium as a dysphemism for titanium. Titanium allowed a higher strength-to-weight ratio at the high temperatures the Blackbird would reach, but the Soviet Union controlled its supply and was trying to deprive the US armed forces of this resource.[b]"
Some rare earth elements are still called unobtaniums in the ore industry.

The term became a joke only relatively recently in fiction, not reality. You gotta love the irony :-)

Don't see any of this giving me a chuckle.

By Steve Blackband (not verified) on 22 Oct 2017 #permalink


What? No warp drive and inertial dampness in the real world. Heresy my man!!!!!

I like the idea of a practical starship that uses acceleration for gravity and the 'Empire State' rocket. Then, half way to the destination you decelerate, giving G with everyone flipping over and standing on the roof and flipping over equipment etc. Slow, but would work.You could live without G for the short time switching from acceleration to deceleration, and for the short time in in orbit before landing. A bit dull - you pretty much only fly straight. No Starship Enterprise swooping around - sadness. At least you could turn a little but it would have to be slow, an acceptable fraction of G. Or I guess a few G's if everyone straps in for the turns.

By Steve Blackband (not verified) on 22 Oct 2017 #permalink

Surely this has all been thought of before.

By Steve Blackband (not verified) on 22 Oct 2017 #permalink

Or when decelerating you simply flip the ship around 180, have engines on the top too, or some way to redirect the thrust at the other end.

By Steve Blackband (not verified) on 22 Oct 2017 #permalink

A friend pointed out a big science blooper in the movie Passengers.
That does the rotating thing forartifical gravity. Theres a pretty cool special effects scene where Lawrence is swimming in a pool, they loose power, the gravity stops, and she's trapped inside a large wibbly wobbly ball of water trying to swim out. I struggle visualizing how swimming would be in zero G.

That said, the artificial gravity goes away because the ring stops rotating. BUT if you've powered up the ring, and made a good virtually frictionless interface with rest of the ship, why would it stop spinning when you loose power? It should continue until a force slows it down - basic Newton.

By Steve Blackband (not verified) on 22 Oct 2017 #permalink

"I think I might have read somewhere that sleep in zero g has benefits."

Can you find that for me - would be interesting. I can't find any 'benefits' per se, just that many astronauts say it feels comfy since there is no pressure on the body. Comfy isn't really a benefit, since its counteracted by the 90 minute day on the space station at least, and without a normal day cycle your circadian clocks go out of whack. Apparently sleeping pills are the drug requested most by the astronauts. And theres all the other lovely things that start happening like muscle loss and retinal detachment etc.
Is it possible you've confused this with the adverts for supposed zero gravity beds on Earth, which aren't??

The astronauts on the ISS also greatly miss showers (Skylab had a shower). An important side note is that you need to sleep in a well ventilated place - without G, the CO2 you breathe out stays around you and you could suffocate!!

By Steve Blackband (not verified) on 22 Oct 2017 #permalink