Centrifugal Gravity

Simulated gravity created within a spaceship, Space Station, or habitat by spinning it.

Currently, science has no way to create gravity where celestial bodies dictate there would be none, or a negligible amount. The only substitute is to otherwise cause acceleration toward stable surfaces. Accelerating in a straight line would constantly use up fuel and produce unwanted velocity, so the most practical solution is to travel in a circular path, causing constant acceleration toward the center.

The biggest obstacle to this trope in Real Life is the impracticality of making large enough centrifuges. Your ears are very good at sensing motion and gravity (it's how you balance) and while you're being spun around in a small centrifuge, you're subject to the Coriolis Effect, and so if you happen to turn your head to look left or right, you'd feel nauseous (as many who have ridden in the Gravitron could tell you). The benefits of gravity simply didn't justify the extravagant cost that designing a spinning space station would require. ^note Especially considering they'd have to design it to handle emergency situations that would necessitate the station to stop moving; in other words, everything would have to be designed to operate in two modes. This would have made the project several hundreds to several thousands of times more expensive than it already would be. NASA and other space programs simply weren't willing to design what would essentially be a multi-billion dollar failure-prone space puke bucket. This being said, a modest reduction in the cost of building a station would make this worthwhile for very large stations that could turn more slowly (which would also not run into the nausea issue as much); however, there is nothing today to make such large stations possible or desirable.

Usually appears in hard science fiction; in softer works you can get away with generating Artificial Gravity by throwing enough Applied Phlebotinum at the problem, instead. (Which also tends to be easier to film or animate... Not every production can afford to build a giant centrifuge for its actors to walk around in à la 2001!) Some very hard SF works will actively use a necessary side effect of centrifugal gravity: the amount of gravity you feel depends on your distance from the center of rotation. If the spaceship or space station has multiple decks, then objects and people on "upper" (closer to the center of rotation) decks will feel a slightly lower level of gravity than objects and people on "lower" (farther from the center of rotation) decks do. This can be used to produce downplayed versions of Heavyworlders and Lightworlders on the same ship.

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Examples

Anime and Manga

• Doraemon: Nobita and the Steel Troops: This is how Zanda Claus, a Humongous Mecha piloted by the gang, managed to maintain it's interior gravity. The trope is actually mentioned by name; the gang is seated in the cockpit located in the robot's stomach area, and as Shizuka asks why "aren't they feeling dizzy" while the robot is performing summersaults, Doraemon then replies "the robot probably have it's own centrifugal gravity system" before explaining what it meant.
• The Gundam franchise helped popularize the O'Neill Cylinder space colony (see below in "Literature"), as well as other designs. The franchise also consistently shows characters on spaceships and spacestations as being in zero-g, unless the ship/station happens to have a rotating section to provide that gravity.
  • Mobile Suit Zeta Gundam's Cool Ship, the Argama, has residential blocks which can extend on telescoping arms and rotate for this reason.
• In Cowboy Bebop most space stations are the ring type. The Bebop and many other ships have rotating sections that seem like they would serve the same purpose, but the portrayal is inconsistent and vague about what rooms are in or outside the ring. Even more strangely, when the Bebop is parked is on a planet, the ring is stationary about a horizontal axis, yet the crew can walk around normally in rooms that should be upside down or sideways.
• The Amaterasu of Starship Operators has a rotating crew section, the showers have signs warning about Coriolis forces.
• The Orbital Children: The artificial gravity aboard the Anshin is created this way, and different chambers based on different planets spin at different speeds to represent their respective gravity levels.

Comic Books

• A Defenders storyline centered on the Tunnelworld.

Fan Works

• This is the only Artificial Gravity tech known to the Kerbals in The Next Frontier. Prototype FTL ship Starfarer 1 uses the older, less convenient but mechanically simpler method that requires spinning the whole ship rather than using two contra-rotating gravity wheels.

Film

• 2001: A Space Odyssey;
  • The Discovery One from in the original used the centrifugal method of gravity generation onboard both the space station and the Discovery. It's notable that the non-rotating parts of Discovery and the famous shuttle sequence near the beginning are as being zero gee, through actors walking strangely in "velcro booties", and dangling props from wires, etc.
  • A special rotating set had to be built for this effect.
  • On the other hand gravity in the Moonbase appears to be Earth-normal without explanation.
  • Likewise the Alexei Leonov in the sequel, 2010: The Year We Make Contact, with a segment of the ship designed to rotate when not under thrust to generate pseudo-gravity. In contrast with 2001, less effort is spent to maintain the illusion of zero gee elsewhere, making this a Hand Wave rather than a serious effort at realism (though there is one scene on the zero-g bridge of the Leonov where Dr. Floyd demonstrates his proposal for linking the two ships using floating pens). But even that scene is off because only the pens are in zero-g. Everyone else is standing around in normal gravity.
• The Venture Star in Avatar has a centrifuge section; the only scene aboard it, though, takes place in a free fall zone.
• The Cloverfield Paradox. The space station has several spinning drums to provide gravity. However, people are walking on floors of those drums instead of the rims. Additionally, there don't seem to be any access tunnels connecting central hubs of those drums to the rest of the station. The only way in and out appears to be diving from the rim of the spinning drum into a static corridor outside, and doing it fast enough to not be seared by the wall—this is never shown onscreen.
• Possibly one of the oldest examples: "The Wheel" in George Pal's 1955 movie Conquest of Space, which is basically a space station built in the shape of a wheel to allow the crew artificial gravity. Outside "The Wheel" and on the spaceship, the characters are weightless and have to rely on magnetic boots.
• The ship in Disney's Rocket Man also has this type of gravity, with several sections spinning around a central node, connected by cables (see the Real Life proposal below). Strangely enough, gravity goes from zero to normal in a split second, causing the protagonist to drop instantly. In fact, it would take a long time to "spin up" to anything even remotely like normal Earth gravity. Near the end, the protagonist and his Love Interest are dancing. The Commander disengages the gravity, and they're shown dancing on a wall and on the ceiling, which isn't how weightlessness works.
• Elysium: The Elysium station rotates to provide this. The station notably has its inner rim open to space, since the air is held in by its gravity as well.
• The Endurance of Interstellar includes a spinning ring of modules where the astronauts spend most of their time.
• Like the novel, the Hermes in The Martian sports Centrifugal Gravity for the long journey between Earth and Mars. Unlike other depictions, the astronauts are shown floating freely about the center of the ship, only experiencing the increasing pull of shipboard gravity as they descend via ladder into the spinning section.
• Used as a plot-point in Moonraker. Hugo Drax's secret space station spins on its axis, providing gravity to those inside. James Bond is being held prisoner, but hits the button to stop the station rotating, causing everyone to slam into the walls and then start floating around in zero-gravity. However, Drax's space station was not cylindrical; rather it had a roughly spherical central portion with long appendages sticking out. When it "spins up", gravity is uniform everywhere, and directed towards the "floor" of the main area, when in reality it would vary enormously depending on where in the station you were, and would be directed away from the axis of rotation.
• Parodied in Mystery Science Theater 3000: The Movie, which opens with Mike Nelson running along a circular track... which turns out to be a man-sized hamster wheel, complete with hanging water bottle.
• The Avalon in Passengers consists largely of three curved arms in an outwards spiral formation that spin to provide gravity. The elevators that go between sections go without gravity at points. When the power fails temporarily the ship stops spinning and things all over start floating, totally ignoring the laws of inertia.
• Red Planet had a ship that used centrifugal sections for gravity. They take it one step closer to realism by having two sections rotating in opposite directions, as rotation in one direction only would throw the ship off course and end up wasting a lot of fuel to correct.
  • Rotating in one direction will do nothing to alter a spacecraft's course — the Apollo missions all rotated slowly on the way to the moon so as to avoid baking one side in direct sunlight for too long. The reason opposite-direction rotating sections is more practical is to avoid having the central hub of your spacecraft rotate in the opposite direction when your one rotating section is "spun up", or rotate in the same direction due to friction in the bearings.
  • Also, having two counter-rotating sections means angular momentum is cancelled out, making the ship much easier to maneuver.
• One of the ships docking at the Space Station at the start of Valerian and the City of a Thousand Planets has spinning rings that generate gravity.
• Stowaway (2021) uses a spent booster tethered to the habitation module as a counterweight.

Literature

• Beyond Infinity: The protagonists spend a brief time trapped in a Tunnelworld after an encounter with some 4-dimensional aliens. It was a closed loop, so traveling in any direction for a long enough time would return you to your point of origin.
• The Culture of Iain Banks's novels builds Ringworld-style Orbitals (but smaller) as housing for many of its citizens. They have a few full size, fits-round-a-star Ringworlds, too, but they're much rarer, since you can get more usable area by using the same mass to build orbitals so most of the Culture regards them as tacky. Notably, this is a setting in which anti-gravity devices are common and reliable, but because the centrifugal force is not the same fundamental force as gravity (even if the net effect ends up the same) those anti-gravity devices will not function on a ring orbital as they would on a planet.
• Larry Niven:
  • Footfall by Niven and Jerry Pournelle has the Fithp alien invaders use a ship which sometimes spins for gravity and sometimes not, depending on its current mission role. It is designed so rooms can adjust for whether gravity is present or not.
  • The Mote in God's Eye: Niven and Pournelle had human starships use the same set-up as the Fithp ship in Footfall. In this story, the alien Moties are unbothered by a lack of gravity ( possibly due to mutation or genetic engineering during one of their many Cycles).
  • Ringworld is set on a world shaped like a vast ring with a sun at its centre. It's made of Unobtanium called scrith and is so massive that its geographical features include 1:1-scale maps of several planets (including Earth). These maps are significantly less than 1% of the ring's surface area.
• Orphans of the Sky: The entire ship is rotating on its long axis (although its inhabitants are as ignorant of this fact as the inhabitants of Earth once were of Earth's rotation); the higher-gravity levels where the Crew live are actually farther out towards the outer hull of the spaceship, while the lower-gravity areas where the Muties live are closer in towards the center (including a zero-gravity area along the Ship's main axis).
• Rendezvous with Rama: Rama is a massive hollow cylinder, and rotates around its long axis to provide gravity to its inner axis.

• Gerard O'Neill proposed a real world cylindrical space colony: Island Three. The page illustration is a representation of the "Stanford Torus", another design inspired by both O'Neill's work and the classic "wheel-and-hub" space stations.
• Thistledown, from Greg Bear's The Way Series, is a hollowed-out asteroid containing seven cylindrical chambers separated by bulkheads. The seventh chamber connects to a cylindrical pocket universe with several million miles of terraformed interior.
• The Anne McCaffrey and S. M. Stirling The Ship Who... novel The City Who Fought takes place entirely on a cylindrical space station.
• In the Gor series, the alien Kur race live on "steel worlds" hidden in the Asteroid Belt. The book Kur of Gor takes place on one, and we learn that it is like this. You can look up and see the opposite "land" side. Day and night are controlled artificially, as is weather. At one point they travel to one of the ends, where the gravity is pracitally non-existent.
• The Battle School of the Ender's Game series is built as a ring. Bean deduces from emergency exit maps that it's larger than they're told, and there were plans to build more rings connected around it. Subverted as, during the events of that book, they realized the gravity was constant throughout the station but suddenly cut off at the entrance to the Battle Room, implying that it was actually using Artificial Gravity (a technology supposedly reverse-engineered from Bugger technology following the First Invasion).
  • In the prequel Earth Unaware asteroid mining ships have a "fuge" aboard where the crew exercise and small children are raised. The rest of the ship is in microgravity. Interestingly, the same prequel novel also reveals that humanity had already made some progress in Artificial Gravity being used for certain military aircraft (specifically, the HERC developed by Juke Ltd. for New Zealand) as a replacement for rotors. This retcons the origin of Artificial Gravity as a purely human invention rather than technology learned from the Buggers.
• In Destruction Of Phaena by Alexander Kazantsev, the eponymous planet's first (and last) space station was a ring that used centrifugal forces to emulate gravity. There was also a compartment in the middle of the ring, where they grew edible plants, which profited from the lack of "gravity".
• The Whorl in Gene Wolfe's Book of the Long Sun is a rotating cylindrical spaceship. "Whorl" obviously refers to its rotation, but has become confused in the minds of its inhabitants with "world" to the extent that they also call planets whorls.
• Robert A. Heinlein used this a lot:
  • The Cat Who Walks Through Walls opens on a space station of multiple levels and multiple rings.
  • In Space Cadet (Heinlein), the concept of centrifugal gravity and some of the math is explained in the form of lessons for Cadet Matt Dodson and his fellow cadets.
  • The Rolling Stones (1952) has a mention of non-symmetric spaceships that can rotate end-over-end to create pseudogravity for the benefit of passengers who can't or don't want to live in free-fall. Trickster Twins (and space rookies) Castor and Pollux, who are trying much too hard to sound like experienced spacers themselves, look down on these "tumbling pigeons".
  • Orphans of the Sky features an enormous slower-than-light starship (whose inhabitants have forgotten they are even on a ship of any kind after a mutiny generations ago) which spins on its long axis to provide varying levels of artificial gravity to different parts of the ship (with a zero-gravity area along the ship's main axis).
• A rotating space station is depicted in the 1959 children's book You Will Go to the Moon by Mae and Ira Freeman.
• Reach by Edward Gibson. The Wayfarer 2 sent to the far reaches of the solar system is actually two vessels, joined by a tether, which are then spun.
• Reborn as a Space Mercenary: I Woke Up Piloting the Strongest Starship!. Implied with Tarmein Prime, the first Space Station Hiro visits upon waking up inside Stella Online. It isn't directly discussed, but the colony is a a bicycle-wheel-style design with buildings built along the interior rim.
• In Revelation Space, the Nostalgia for Infinity primarily creates gravity by simply accelerating at a constant 1g using its Conjoiner Drive engines - the decks are arranged like that of a skyscraper. However, when not accelerating, the ship can spin up independent centrifuge sections for the (nonexistent) passengers. Most orbital habitats in the Glitter Belt (and later, the Rust Belt) orbiting Yellowstone resemble carousels or cola cans, and are spun up to generate gravity on the interior.
• In Sergey Lukyanenko's Star Shadow, the Russian space station Delta is a toroid designed to be able to rotate for this purpose, unlike the other Earth defense stations. It's mentioned to be both a convenience and an inconvenience. It's nice to be able to walk aboard the station, but the rotation must be stopped if lasers are to be used for combat, as it's difficult to aim this way.
• Star Carrier: The eponymous America has twin counter-rotating habitation rings that are kept at about .5 gravities, due to the mixed crews from bodies all over the Sol system (Earth has 1 G, the Moon has 1/6, etc.). These are also used as an alternative way to launch Space Fighters, by placing them in slots on the rim of the ring and letting inertia fling them clear of the carrier's shield cap.
• Earthclan's ships in the Uplift series have a rotating ring section, even after obtaining Artificial Gravity from the Galactic Library. Partially because they don't fully trust the Library and partially to remind the Galactics of their status as un-uplifted "Wolflings". Unfortunately this means that most of the dry (the dolphin crew don't mind null-g much) rooms on the Streaker are upside-down or sideways whenever they're grounded.
• This is one of two types of artificial gravity that Greg Egan plays straight in his Orthogonal trilogy. The protagonists fly their Generation Ship to an Alternate Dimension by accelerating the ship to an infinite velocity at a rate of one-G for about a year. When they turn off the engines and stop accelerating, the lack of gravity unexpectedly causes their crops to fail, so they begin spinning the ship to compensate.
• All starships and Space Stations in the Alliance/Union and Foreigner (1994) universes of C. J. Cherryh use this, as her sci-fi is on the "hard" end of the scale.
• The Ring from For Your Safety is a massive Earth girdling space colony at geosynchronous orbit.
• Paradyzja by Janusz Zajdel has centrifugal gravity on the titular space station. Or so they're telling you...
• The Hermes from The Martian sports this, which keeps the astronauts in shape during the long journey to and from Mars during the Ares missions.
• In Captain French, or the Quest for Paradise, the titular space trader's ship, the Circe, is equipped with ion thrusters that maintain a rotation of the ship at 0.2g. In order to keep himself from becoming a Sacabon, he forces himself to exercise daily and swim in his Olympic-size pool while traveling.
• At the end of the David Brin & Gregory Benford novel Heart Of The Comet, the colonists living in the comet have finally figured out the problem of how to raise viable children on a ball of ice and rock with significantly reduced gravity: they refurbish a Ferris wheel-like set of chambers in one of the comet's caverns, where all the children are raised in simulated gravity. Crew members are also mandated to spend a certain amount of time in the gravity rooms to keep their bodies from atrophying.
  "...the centrifugal wheel from the old Edmund had been refurbished and put back to work, rotating slowly, like a Ferris wheel... The wheel's centrifugal force was equivalent only to one twentieth of Earth's pull, but it was enough... As he approached the rolling boundary, Saul heard a treasured sound. Children laughed and flew past him towards the ring, skidding in the soft sand of the landing area as the great cylinder rolled around and around. They looked so much better. Still, the gangling forms seemed barely human. Only a few could speak."
• Seveneves, set 20 Minutes into the Future has a spinning torus attached to the ISS. The Cloud Ark later in the novel uses multiple small spaceships tethered together as "bolas" (see the Real Life section). Post Time Skip the "Eye" habitat (and its Red counterpart, the "Fist") are using this as well.
• This and thrust gravity are the only way humans can generate gravity in The Expanse. Some asteroids (and even Ceres) are also spun up to provide at least a modicum of gravity. The Nauvoo was meant to be a gigantic Generation Ship using an O'Neill Cylinder to provide gravity for agriculture. Its drum is first spun up to provide gravity for the wounded in the "slow zone" as the Behemoth, and it is used for its intended agricultural purpose later as the Medina Station.
  • Unlike most other examples, the books actually do address the issues of coriolis and its Nausea Fuel properties. It specifically mentions that moving closer to the hub of a spinning station causes you to feel less gravity and more coriolis, and that people who aren't used to the sensation often find it quite disorienting and nauseating.
• In Kea's Flight, the Flying Dustbin is shaped like a giant spinning cylinder.
• In The Outside, the Pride of Jai is shaped like a giant wheel that rotates to create gravity.
• In Project Hail Mary, the titular ship has a variation on this. When the engines are on, they provide thrust gravity, but when they’re off, the ship’s habitat section detaches from the engine and fuel sections while still being connected with thin cables. Then the habitat rotates so that the “nose” is pointing at the fuel section, and the whole ship spins up to provide centrifugal gravity in the habitat. Here’s a video that shows how it works: https://m.youtube.com/watch?v=_IWGMN0vF-w
• The ship used to reach the eponymous planet in Ben Bova's novel Mars has the crew section at the end of a long tether which spins around the drive/command section to provide artificial gravity for the crew during the voyage.
• In Incandescence, the Aloof house Rakesh and Parantham in a spinning habitat so they can walk around comfortably while they study the DNA-infested meteor.
• Transpecial: Although the technology for true Artificial Gravity exists, centrifugal gravity is cheaper, so many space stations consist of spinning habitat rings. General Anthony dislikes the spin because looking out the viewports makes him queasy.

Live-Action TV

• The Ark (2023): Portrayed inconsistently. In the first few minutes of the pilot; Garnet has to stop the rotation of the spinning section of the Ark 1 starship the cryo bay is in, predictably leading to the survivors floating in the corridor. When she restarts the rotation, everyone falls to the floor. But throughout the rest of the show, everywhere on all the Arks has the same 1-g gravity regardless of it it is spinning or not and with little regard for the direction of the gravity between locations.
• Babylon 5: The eponymous space station is an O'Neill Cylinder, a huge cylinder in space that spins on its long axis to produce centrifugal gravity. The most advanced Earth Alliance ships, such as Explorers and Omega-class destroyers, have a large rotating central section, so that at least the crew quarters and mess areas can have gravity. More advanced races such as the Centauri and Minbari have Artificial Gravity, and everyone else without it uses seatbelts.
• The civilian ship Zephyr (the "Donut Ship") in Battlestar Galactica (2003) consisted of a ring-shaped section rotating around a central axis. Word of God said the ship is a relic from when gravity on starships were created through centrifugal force. Although proper artificial gravity was widespread by the time the series begun, Zephyr and its type were kept in commercial use for novelty value.
• The 100 uses this to explain the artificial gravity on The Ark.
• In The Expanse, constant thrust and centrifugal force are the only two sources of artificial gravity. Celestial bodies, like Ceres and Eros, are artificially spun-up to generate gravity while stations, like Tycho, and some ships, like the Nauvoo, use spinning drums.
• The Polaris space hotel in the third season of For All Mankind has a rotating ring. A space debris incident causes the thrusters to fire continuously and the ring to spin faster, resulting in crushing G-forces until the problem is resolved. Later, it is made part of an interplanetary Mars ship called Phoenix.

Tabletop Games

• Dungeons & Dragons
  • Sigil from Planescape setting is a small torus. It's also a sort of hub that connects to all the other planes of existence.
  • There's also Penumbra, the illithid homeworld, which is a full Ringworld. It may or may not exist yet.
• In Eclipse Phase many people following the Fall live in space habitats, many of the bigger ones are toruses or O'Neil cylinders. However there's also a number of habitats that don't bother with spinning since basic biomods counter the degeneration from microgravity.
• 2300 AD does this with human-built ships. Justified in that it's trying to be a hard science setting.
• The Mundane Dogmatic BattleTech universe lacks conventional artificial gravity, forcing ships to make do with "grav deck" centrifuges or ship acceleration for pseudo-gravity. JumpShips which just hang around a star's nadir points while recharging make the most use of centrifugal gravity, whereas Drop Ships continuously accelerate in intra-system travel, providing pseudo-gravity. Prohibitive costs and maintenance means that there's generally more crew than room on the centrifuges, so space on the centrifuges are generally relegated to exercise, entertainment, and medical bays, with crew being allotted a certain amount of time per day in centrifuge areas. Centrifuges are most obvious on the descriptively named Wagon Wheel class of WarShips, which has a trio of nested centrifuges mounted on the exterior of the fuselage.
• Traveller has optional rules for ships with "hamster cages" or nested rotating hulls that provide gravity through spin instead of using artificial gravity. They're expensive and a bit awkward to maneuver with, but the savings on a hull without gravity generators compensate.

Video Games

• The Elite series features this in its Space Stations, as artificial gravity is nonexistent. Their spin makes docking difficult, as pilots must match the spin or risk crashing into the (wide, but relatively narrow) airlock "slot". In Dangerous, you still need to match rotation until you pass through the airlock, at which point your ship's computers will automatically manage rotation and fire the RCS as-necessary to adjust for this rotation for you... though if you're feeling adventurous (or want to show off) you can easily disable this option and touch down on pads the hard way. Or you can just use an autodocking computer which will do everything for you from start to finish.
• FTL: Faster Than Light Multiverse, a mod for FTL: Faster Than Light, has the Kasparov-Class, an antiquated human-built spaceship that was the first class to ever make an FTL Jump. Older than most tech in the setting, it lacks artificial gravity and instead uses a centrifuge ring. Some of the Leech fleetships are old enough to possess a 'whisk' structure which span to produce gravity. Most of them have been overhauled with more modern tech, however, and the hull are simply in use because the leeches are suffering economic issues.
• In the expansions of Galactic Civilizations 2 the limitations of centrifugal force are discussed in the description for the "Artificial Gravity" tech. Apparently during the stargate era a Drengin troop transport once had an arm motor jam and toss thousands of troops out into space. A number of the default human ship designs have rotating sections, in particular the colony ship.
• Halo:
  • Halo: Combat Evolved takes place on a ringworld (Alpha Halo aka Installation 04) resembling Banks's Orbitals set at the midpoint between a gas giant and its moon. Most of the other Halos in the series appear to orbit gas giants as well.
  • In a case of Early-Installment Weirdness, the first novel, Halo: The Fall of Reach, states that most Human ships have indoor rotating sections to simulate gravity using this trope, including the Pillar of Autumn. Yet these are never seen in any of the Autumn levels of the first game, and the idea itself is retconned in later novels which have humans use regular Artificial Gravity instead.
• In Mass Effect, while artificial gravity is standard on most ships, the Citadel is mentioned as using centrifugal force, giving the Ward Arms a comfortable standard 1.02 G's, while the Presidium Ring is a lighter 0.3 G's. The Presidium itself also takes the form of a Stanford Torus. There are public notices telling people not to throw things because they will gravitate toward the windows.
• Many Earth ships in Nexus: The Jupiter Incident have large centrifuge sections to generate gravity for the crew. This is because it frequently takes weeks, if not months to travel anywhere in the Solar System. No one else uses these, as they have Artificial Gravity, Interplanetary Drives (that can shorten the same trip to days or even hours), and wormholes for intersystem jumps.
• In the Outer Wilds: Echoes of the Eye expansion, the unnamed aliens who built the Stranger rely on this, which can make docking with the station tricky. It's another way to contrast these aliens with the Nomai who feature so heavily in the base game, since they were able to generate Artificial Gravity with the help of glowing purple Power Crystals.
• Shores of Hazeron has ancient ringworlds which can be colonized. The ringworlds are almost exactly like those from the Ringworld novel, with mountains flanking the inner walls, and with shadow squares creating day/night cycles on the surface.
• You can make ringworlds in the Space Empires series. A Dyson Sphere is better, though.
• You can build ringworlds in Star Ruler, admittedly as a lategame option. They are Capital-H Huge, larger than some planetary orbits.
• Startopia has you turn one of these into a profitable space station. Or several, actually. Apparently, all known races use the same exact design for their space stations, right down to the color scheme.
• The eponymous station in Tacoma uses this system to ensure that the contractors working there over several months remain healthy, with each section connected by a central corridor. Travel between the central corridor and each of the sections is facilitated by a lift designed to ease the rider from zero-g to normal Earthlike gravity (as well as disguise the loading of each section by the game).
• In the X-Universe series, both Argon and Teladi trading stations and shipyards have large centrifuge sections to generate gravity for its occupants and workers. In Xtended Terran Conflict, all Teladi space stations have a rotating centrifuge at their core, along with several new ships having small centrifuges. In X: Rebirth, Teladi capital ship freighters have a centrifuge section, and their sole space station is a colossal dozen-kilometer wide Ringworld Planet-esque space station; habitats run along the rim of the wheel, while the core of the station has docking and manufacturing centers.

Web Original

• The world of Pendor, from The Journal Entries of Kennet Shardik, is Niven's Ringworld with the Serial Numbers Filed Off, because Niven had threatened to sue Elf Sternberg over writing gay BDSM Known Space fanfic of the Kzin.
• Darwin's Soldiers: Card of Ten takes place primarily on one of these.
• Practically the only means of simulating gravity in Orion's Arm. There are even Banks Orbitals and Niven-style Ringworlds, which generally require magmatter to construct because of their size. The archailects might be able to produce Artificial Gravity with spacetime engineering but they generally don't because it would be too inefficient (ex. a small black hole).
• In Starsnatcher, this is how space stations like Euphrat and space ships like the Dragonfly (when they’re not accelerating) keep the boots on the ground. It’s noted that space stations are less likely to produce nausea from the Coriolis effect due to their greater size. In space ships, however, the risk is high. Lucas only survived in the Dragonfly so well because he spent most of his time in virtual reality.

Web Comics

• Schlock Mercenary: While Artificial Gravity via manipulating existing internal gravity sources is in regular use among the various space-faring sophont races, there are a few exceptions:
  • The space station Credomar is a cylinder designed to make use of this, but it's considered to be so inefficient that it's a mystery why anyone would build a space station like that. It's eventually revealed that Credomar wasn't really a space station, but a Wave-Motion Gun turned into a space station to prevent its use as a weapon.
  • Earth's original stepping stone to the stars, MEL-One (Moon-Earth Lagrange point One) spins to generate its gravity. As a historical landmark, except for the crew quarters it retains centrifugal gravity.
  • The Planet Mercenary RPG spin-off makes not of another, very complex example with multiple independent rotating sections around Gripp, the Fobott'r homeworld. Built just after the Fobott'r reconqured their homeworld, it was built as a sign that they could manage as a space-going people just fine despite being embargoed by the wider galaxy. It's maintained as a combination of historical significance, tourist magnet and display of engineering prowess.
• The orbital space-cities featured in Episode Three of Space Kid.
• In Questionable Content, the Space Station where Hannalore grew up is of the "pencil-and-donut" design, as seen best in #2111.
• Leaving the Cradle haves only one ship with artificial gravity. It is a humongous mothership that hosts an entire small city inside of it.
• Freefall: The Space Station where Winston's parents live is built in two large counterbalancing arcs tethered together, rotating around a central point. It's a good substitute for the sci-fi setting's lack of Artificial Gravity, but does cause vertigo in some newcomers.
  Gregor: There is also a psychological component. It is easy to believe the room is spinning when you know for a fact the room is actually spinning.

Western Animation

• Archer "Space Race": The ISS Horizon has gravity thanks to its central cylinder spinning on its longitudinal axis. The central cylinder is divided up into separate sections that are spinning in opposite directions.

Real Life

• Conventional centrifuges are a subversion, used not to create "gravity" where there is none, but to increase it.
• The Japanese Centrifuge Accommodations Module for the ISS would have housed a centrifuge unit for biological research. It was built, but never added to the station due the loss of the space shuttle Columbia in 2003 and the small number of subsequent shuttle flights leaving no way to carry it up. The centrifuge was only 2.5 meters across and could only hold racks less than about 2 feet high, balanced with one on either side of the axis, so it would never have fit an astronaut.
• The crew of Skylab were able to simulate this somewhat, not by spinning their space station, but by running along a convenient ring of panels. See it here. They moved slowly enough that the acceleration difference between their heads and their feet was not too great to tolerate.
• While it is typical to see a spacecraft mount a separate spinning unit for centrifugal gravity, it is possible to skip the moving parts and spin up the whole craft (a "tumbling pigeon" design), with the tricky bit being pointing an antenna at Earth all the while.
  • An even crazier design (albeit backed by Buzz Aldrin in his Mars proposals) is the "bola", which has two sections of the craft connected by cables to get the longest possible distance from the barycenter with the least required mass.
• Carnival or theme park rides sometime incorporate the effect; a classic ride, called "The Rotor," placed riders inside a cylinder which was spun vertically. After sufficient speed was achieved, the floor would drop away, leaving the riders "stuck" to the wall. Some of the more "adventurous" would be able to actually sit upright against the wall, until the end of the ride.
• If you want to play with rotating space stations and spaceships on paper, the only math you need is algebra skill and a few simple equations. No calculus required.
  • The time it will take for a space station with a radius r (Radius is the distance from the middle of the wheel to the edge) and simulating Earth gravity (9.8 meters per second squared) can be found by 2π(√( r ÷ 9.8)) or if you want to be walked through step by step:
    • Figure out the radius you want in meters - for this equation convert feet or miles or kilometers to meters - it won't work otherwise. (one foot is .3 meters. One mile is 1600 meters.)
    • Let's say we're doing a radius of 1000 meters (1 kilometer, or .6 mile - that would be a wheel 2 km diameter - across - or 1.2 miles across)
    • Divide the meters by 9.8 (1000 ÷ 9.8 = 102)
    • take the square root of that answer. (~10.1)
    • Multiply by 2 and then π (3.14) (10.1 x 2 = 20.2. Then 20.2 x 3.14 = 63.4 )
    • Our 2km across space station generating earth gravity for its inhabitants would rotate once every 63 and a half seconds. That's a little slower than the minute hand on an analog clock.

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