
Artificial gravity is the creation of an
inertial force that mimics the effects of a
gravitational force, usually by
rotation
Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...
.
Artificial gravity, or rotational gravity, is thus the appearance of a
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parallel ...
in a
rotating frame of reference
A rotating frame of reference is a special case of a non-inertial reference frame that is rotating relative to an inertial reference frame. An everyday example of a rotating reference frame is the surface of the Earth. (This article considers only ...
(the transmission of
centripetal acceleration via
normal force in the non-rotating frame of reference), as opposed to the force experienced in
linear acceleration, which by the
equivalence principle is indistinguishable from gravity.
In a more general sense, "artificial gravity" may also refer to the effect of linear acceleration, e.g. by means of a
rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive Jet (fluid), jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, i ...
.
Rotational simulated gravity has been used in simulations to help astronauts train for extreme conditions.
Rotational simulated gravity has been proposed as a solution in
human spaceflight to the adverse
health effects caused by prolonged weightlessness.
However, there are no current practical outer space applications of artificial gravity for humans due to concerns about the size and cost of a spacecraft necessary to produce a useful
centripetal force
A centripetal force (from Latin ''centrum'', "center" and ''petere'', "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous c ...
comparable to the gravitational field strength on Earth (''g'').
Scientists are concerned about the effect of such a system on the inner ear of the occupants. The concern is that using centripetal force to create artificial gravity will cause disturbances in the inner ear leading to nausea and disorientation. The adverse effects may prove intolerable for the occupants.
Centripetal force

In the context of a rotating space station it is the radial force provided by the spacecraft's hull that acts as centripetal force. Thus, the "gravity" force felt by an object is the
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parallel ...
perceived in the
rotating frame of reference
A rotating frame of reference is a special case of a non-inertial reference frame that is rotating relative to an inertial reference frame. An everyday example of a rotating reference frame is the surface of the Earth. (This article considers only ...
as pointing "downwards" towards the hull.
In accordance with
Newton's Third Law
Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:
# A body remains at rest, or in moti ...
the value of
little ''g'' (the perceived "downward" acceleration) is equal in magnitude and opposite in direction to the centripetal acceleration.
Differences from normal gravity
From the perspective of people rotating with the habitat, artificial gravity by rotation behaves similarly to normal gravity but with the following differences, which can be mitigated by increasing the radius of a space station.
* Centrifugal force varies with distance: Unlike real gravity, the apparent centrifugal force felt by observers in the habitat pushes radially outward from the axis, and the centrifugal force is directly proportional to the distance from the axis of the habitat. With a small radius of rotation, a standing person's head would feel significantly less gravity than their feet.
Likewise, passengers who move in a space station experience changes in apparent weight in different parts of the body.
* The
Coriolis effect
In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the ...
gives an apparent force that acts on objects that are moving relative to a rotating reference frame. This apparent force 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. If an
astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
inside a rotating artificial gravity environment moves towards or away from the axis of rotation, they will feel a force pushing them in or against the direction of spin. These forces act on the
semicircular canals of the inner ear and can cause
dizziness
Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness.
Dizziness is a common medical ...
.
Lengthening the period of rotation (lower spin rate) reduces the Coriolis force and its effects. It is generally believed that at 2
rpm or less, no adverse effects from the Coriolis forces will occur, although humans have been shown to adapt to rates as high as 23
rpm.
* Changes in the rotation axis or rate of a spin would cause a disturbance in the artificial gravity field and stimulate the semicircular canals (refer above). Thus, the rotation of a space station would need to be adequately stabilized, and any operations to deliberately change the rotation would need to be done slowly enough as to be imperceptible.
Human spaceflight
The
Gemini 11 mission attempted to produce artificial gravity by rotating the capsule around the
Agena Target Vehicle to which it was attached by a 36-meter tether. They were able to generate a small amount of artificial gravity, about 0.00015 ''g'', by firing their side thrusters to slowly rotate the combined craft like a slow-motion pair of
bolas.
The resultant force was too small to be felt by either astronaut, but objects were observed moving towards the "floor" of the capsule.
[Clément G, Bukley A (2007) Artificial Gravity. Springer: New York]
Health benefits

Artificial gravity has been suggested as a solution to various health risks associated with spaceflight.
In 1964, the
Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
space program believed that a human could not survive more than 14 days in space for fear that the
heart
The heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon diox ...
and
blood vessels
Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away fro ...
would be unable to adapt to the weightless conditions. This fear was eventually discovered to be unfounded as spaceflights have now lasted up to 437 consecutive days, with missions aboard the International Space Station commonly lasting 6 months. However, the question of human safety in space did launch an investigation into the physical effects of prolonged exposure to weightlessness. In June 1991, a
Spacelab Life Sciences 1 flight performed 18 experiments on two men and two women over a period of nine days. In an environment without gravity, it was concluded that the response of
white blood cells
White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
and
muscle
Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other ...
mass decreased. Additionally, within the first 24 hours spent in a weightless environment,
blood volume
Blood volume (volemia) is the volume of blood (blood cells and plasma) in the circulatory system of any individual.
Humans
A typical adult has a blood volume of approximately 5 liters, with females and males having approximately the same blood pe ...
decreased by 10%.
Long weightless periods can cause brain swelling and eyesight problems. Upon return to earth, the effects of prolonged weightlessness continue to affect the human body as fluids pool back to the lower body, the
heart rate
Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and e ...
rises, a drop in
blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressur ...
occurs and there is a reduced tolerance for
exercise
Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness.
It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic s ...
.
Artificial gravity, for its ability to
mimic the behavior of gravity on the human body, has been suggested as one of the most encompassing manners of combating the
physical effects
A practical effect is a special effect produced physically, without computer-generated imagery or other post-production techniques. In some contexts, "special effect" is used as a synonym of "practical effect", in contrast to "visual effect ...
inherent with weightless environments. Other measures that have been suggested as symptomatic treatments include exercise, diet and
Pingvin suits. However, criticism of those methods lies in the fact that they do not fully eliminate the health problems and require a variety of solutions to address all issues. Artificial gravity, in contrast, would remove the weightlessness inherent with space travel. By implementing artificial gravity, space travelers would never have to experience weightlessness or the associated side effects.
Especially in a modern-day six-month journey to
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
, exposure to artificial gravity is suggested in either a continuous or intermittent form to prevent extreme debilitation to the astronauts during travel.
Proposals

A number of proposals have incorporated artificial gravity into their design:
* Discovery II: a 2005 vehicle proposal capable of delivering a 172-metric-ton crew to Jupiter's orbit in 118 days. A very small portion of the 1,690-metric-ton craft would incorporate a centrifugal crew station.
*
Multi-Mission Space Exploration Vehicle (MMSEV): a 2011
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedi ...
proposal for a long-duration crewed space transport vehicle; it included a rotational artificial gravity
space habitat intended to promote crew health for a crew of up to six persons on missions of up to two years in duration. The
torus-ring centrifuge
A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or ...
would utilize both standard metal-frame and
inflatable
An inflatable is an object that can be inflated with a gas, usually with air, but hydrogen, helium and nitrogen are also used. One of several advantages of an inflatable is that it can be stored in a small space when not inflated, since infla ...
spacecraft structures and would provide 0.11 to 0.69
''g'' if built with the diameter option.
[NAUTILUS – X: Multi-Mission Space Exploration Vehicle]
, Mark L. Holderman, ''Future in Space Operations (FISO) Colloquium'', 2011-01-26. Retrieved 2011-01-31[NASA NAUTILUS-X: multi-mission exploration vehicle includes centrifuge, which would be tested at ISS]
, ''RLV and Space Transport News'', 2011-01-28. Retrieved 2011-01-31
*
ISS Centrifuge Demo: a 2011 NASA proposal for a demonstration project preparatory to the final design of the larger torus centrifuge space habitat for the Multi-Mission Space Exploration Vehicle. The structure would have an outside diameter of with a ring interior cross-section diameter of . It would provide 0.08 to 0.51 ''g'' partial gravity. This test and evaluation centrifuge would have the capability to become a Sleep Module for ISS crew.
[
* Mars Direct: A plan for a crewed ]Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
mission created by NASA engineers Robert Zubrin and David Baker in 1990, later expanded upon in Zubrin's 1996 book '' The Case for Mars''. The "Mars Habitat Unit", which would carry astronauts to Mars to join the previously launched "Earth Return Vehicle", would have had artificial gravity generated during flight by tying the spent upper stage of the booster to the Habitat Unit, and setting them both rotating about a common axis.
* The proposed Tempo3 mission rotates two halves of a spacecraft connected by a tether to test the feasibility of simulating gravity on a crewed mission to Mars.
* The Mars Gravity Biosatellite was a proposed mission meant to study the effect of artificial gravity on mammals. An artificial gravity field of 0.38 ''g'' (equivalent to Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
's surface gravity) was to be produced by rotation (32 rpm, radius of ca. 30 cm). Fifteen mice would have orbited Earth (Low Earth orbit
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
) for five weeks and then land alive.[Korzun, Ashley M.; Wagner, Erika B.; et al. (2007)]
Mars Gravity Biosatellite: Engineering, Science, and Education
58th International Astronautical Congress. However, the program was canceled on 24 June 2009, due to lack of funding and shifting priorities at NASA.
Issues with implementation
Some of the reasons that artificial gravity remains unused today in spaceflight
Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in o ...
trace back to the problems inherent in implementation
Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy.
Industry-specific definitions
Computer science
In computer science, an implementation is a real ...
. One of the realistic methods of creating artificial gravity is the centrifugal effect caused by the centripetal force
A centripetal force (from Latin ''centrum'', "center" and ''petere'', "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous c ...
of the floor of a rotating structure pushing up on the person. In that model, however, issues arise in the size of the spacecraft. As expressed by John Page and Matthew Francis, the smaller a spacecraft (the shorter the radius of rotation), the more rapid the rotation that is required. As such, to simulate gravity, it would be better to utilize a larger spacecraft that rotates slowly. The requirements on size with regard to rotation are due to the differing forces on parts of the body at different distances from the axis of rotation. If parts of the body closer to the rotational axis experience a force that is significantly different from parts farther from the axis, then this could have adverse effects. Additionally, questions remain as to what the best way is to initially set the rotating motion in place without disturbing the stability of the whole spacecraft's orbit. At the moment, there is not a ship massive enough to meet the rotation requirements, and the costs associated with building, maintaining, and launching
Ceremonial ship launching involves the performance of ceremonies associated with the process of transferring a vessel to the water. It is a nautical tradition in many cultures, dating back thousands of years, to accompany the physical pro ...
such a craft are extensive.
In general, with the limited health effects present in shorter spaceflights, as well as the high cost of research
Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness t ...
, application of artificial gravity is often stunted and sporadic.
In science fiction
Several science fiction novels, films and series have featured artificial gravity production. In the movie ''2001: A Space Odyssey'', a rotating centrifuge in the ''Discovery'' spacecraft provides artificial gravity.
In the novel '' The Martian'', the ''Hermes'' spacecraft achieves artificial gravity by design; it employs a ringed structure, at whose periphery forces around 40% of Earth's gravity are experienced, similar to Mars' gravity. The movie '' Interstellar'' features a spacecraft called the ''Endurance'' that can rotate on its central axis to create artificial gravity, controlled by retro thrusters on the ship. The 2021 film Stowaway
A stowaway or clandestine traveller is a person who secretly boards a vehicle, such as a ship, an aircraft, a train, cargo truck or bus.
Sometimes, the purpose is to get from one place to another without paying for transportation. In other c ...
features the upper stage of a launch vehicle connected by 450-meter long tethers to the ship's main hull, acting as a counterweight for inertia
Inertia is the idea that an object will continue its current motion until some force causes its speed or direction to change. The term is properly understood as shorthand for "the principle of inertia" as described by Newton in his first law o ...
-based artificial gravity.
Linear acceleration
Linear acceleration is another method of generating artificial gravity, by using the thrust from a spacecraft's engines to create the illusion of being under a gravitational pull. A spacecraft under constant acceleration in a straight line would have the appearance of a gravitational pull in the direction opposite of the acceleration, as the thrust from the engines would cause the spacecraft to "push" itself up into the objects and persons inside of the vessel, thus creating the feeling of weight. This is because of Newton's third law
Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:
# A body remains at rest, or in moti ...
: the weight that one would feel standing in a linearly accelerating spacecraft would not be a true gravitational pull, but simply the reaction of oneself pushing against the craft's hull as it pushes back. Similarly, objects that would otherwise be free-floating within the spacecraft if it were not accelerating would "fall" towards the engines when it started accelerating, as a consequence of Newton's first law: the floating object would remain at rest, while the spacecraft would accelerate towards it, and appear to an observer within that the object was "falling".
To emulate artificial gravity on Earth, spacecraft using linear acceleration gravity may be built similar to a skyscraper, with its engines as the bottom "floor". If the spacecraft were to accelerate at the rate of 1 ''g''—Earth's gravitational pull—the individuals inside would be pressed into the hull at the same force, and thus be able to walk and behave as if they were on Earth.
This form of artificial gravity is desirable because it could functionally create the illusion of a gravity field that is uniform and unidirectional throughout a spacecraft, without the need for large, spinning rings, whose fields may not be uniform, not unidirectional with respect to the spacecraft, and require constant rotation. This would also have the advantage of relatively high speed: a spaceship accelerating at 1 ''g'', 9.8 m/s2, for the first half of the journey, and then decelerating for the other half, could reach Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
within a few days. Similarly, a hypothetical space travel using constant acceleration
Space travel under constant acceleration is a hypothetical method of space travel that involves the use of a propulsion system that generates a constant acceleration rather than the short, impulsive thrusts produced by traditional chemical rock ...
of 1 ''g'' for one year would reach relativistic speeds and allow for a round trip to the nearest star, Proxima Centauri
Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest- ...
. As such, low-impulse but long-term linear acceleration has been proposed for various interplanetary missions. For example, even heavy (100 ton) cargo payloads to Mars could be transported to Mars in and retain approximately 55 percent of the LEO
Leo or Léo may refer to:
Acronyms
* Law enforcement officer
* Law enforcement organisation
* ''Louisville Eccentric Observer'', a free weekly newspaper in Louisville, Kentucky
* Michigan Department of Labor and Economic Opportunity
Arts an ...
vehicle mass upon arrival into a Mars orbit, providing a low-gravity gradient to the spacecraft during the entire journey.[VASIMR VX-200 Performance and Near-term SEP Capability for Unmanned Mars Flight](_blank)
, Tim Glover, Future in Space Operations (FISO) Colloquium, pp. 22, 25, 2011-01-19. Retrieved 2011-02-01
This form of gravity is not without challenges, however. At present, the only practical engines that could propel a vessel fast enough to reach speeds comparable to Earth's gravitational pull require chemical
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...
reaction rockets, which expel reaction mass
Working mass, also referred to as reaction mass, is a mass against which a system operates in order to produce acceleration.
In the case of a chemical rocket, for example, the reaction mass is the product of the burned fuel shot backwards to pro ...
to achieve thrust, and thus the acceleration could only last for as long as a vessel had fuel. The vessel would also need to be constantly accelerating and at a constant speed to maintain the gravitational effect, and thus would not have gravity while stationary, and could experience significant swings in ''g''-forces if the vessel were to accelerate above or below 1 ''g''. Further, for point-to-point journeys, such as Earth-Mars transits, vessels would need to constantly accelerate for half the journey, turn off their engines, perform a 180° flip, reactivate their engines, and then begin decelerating towards the target destination, requiring everything inside the vessel to experience weightlessness and possibly be secured down for the duration of the flip.
A propulsion system with a very high specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...
(that is, good efficiency in the use of reaction mass
Working mass, also referred to as reaction mass, is a mass against which a system operates in order to produce acceleration.
In the case of a chemical rocket, for example, the reaction mass is the product of the burned fuel shot backwards to pro ...
that must be carried along and used for propulsion on the journey) could accelerate more slowly producing useful levels of artificial gravity for long periods of time. A variety of electric propulsion systems provide examples. Two examples of this long-duration, low-thrust, high-impulse propulsion that have either been practically used on spacecraft or are planned in for near-term in-space use are Hall effect thruster
In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thr ...
s and Variable Specific Impulse Magnetoplasma Rocket
The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an electrothermal thruster under development for possible use in spacecraft propulsion. It uses radio waves to ionize and heat an inert propellant, forming a plasma, then a magnetic ...
s (VASIMR). Both provide very high specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...
but relatively low thrust, compared to the more typical chemical reaction rockets. They are thus ideally suited for long-duration firings which would provide limited amounts of, but long-term, milli-''g'' levels of artificial gravity in spacecraft.
In a number of science fiction plots, acceleration is used to produce artificial gravity for interstellar spacecraft, propelled by as yet theoretical or hypothetical means.
This effect of linear acceleration is well understood, and is routinely used for 0 ''g'' cryogenic fluid management for post-launch (subsequent) in-space firings of upper stage
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage ...
rockets.
Roller coaster
A roller coaster, or rollercoaster, is a type of amusement ride that employs a form of elevated railroad track designed with tight turns, steep slopes, and sometimes inversions. Passengers ride along the track in open cars, and the rides ar ...
s, especially launched roller coasters or those that rely on electromagnetic propulsion, can provide linear acceleration "gravity", and so can relatively high acceleration vehicles, such as sports car
A sports car is a car designed with an emphasis on dynamic performance, such as handling, acceleration, top speed, the thrill of driving and racing capability. Sports cars originated in Europe in the early 1900s and are currently produced by ...
s. Linear acceleration can be used to provide air-time on roller coasters and other thrill rides.
Simulating lunar gravity
In January 2022 China was reported by the South China Morning Post to have built a small ( diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
) research facility to simulate low lunar gravity
300px, Radial gravity anomaly at the surface of the Moon in mGal
The acceleration due to gravity on the surface of the Moon is approximately 1.625 m/s2, about 16.6% that on Earth's surface or 0.166 . Over the entire surface, the variation ...
with the help of magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nic ...
s. The facility was reportedly partly inspired by the work of Andre Geim (who later shared the 2010 Nobel Prize in Physics
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
for his research on graphene
Graphene () is an allotrope of carbon consisting of a Single-layer materials, single layer of atoms arranged in a hexagonal lattice nanostructure. ) and Michael Berry (physicist), Michael Berry, who both shared the Ig Nobel Prize
The Ig Nobel Prize ( ) is a satiric prize awarded annually since 1991 to celebrate ten unusual or trivial achievements in scientific research. Its aim is to "honor achievements that first make people laugh, and then make them think." The name o ...
in Physics in 2000
File:2000 Events Collage.png, From left, clockwise: Protests against Bush v. Gore after the 2000 United States presidential election; Heads of state meet for the Millennium Summit; The International Space Station in its infant form as seen from ...
for the magnetic levitation of a frog.[
]
Simulating microgravity
Parabolic flight
''Weightless Wonder'' is the nickname for the NASA aircraft that flies parabolic trajectories and briefly provides a nearly weightless environment in which to train astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
s, conduct research, and film motion pictures. The parabolic trajectory creates a vertical linear acceleration which matches that of gravity, giving zero-''g'' for a short time, usually 20–30 seconds, followed by approximately 1.8g for a similar period. The nickname Vomit Comet is also used to refer to motion sickness that is often experienced by the aircraft passengers during these parabolic trajectories. Such reduced gravity aircraft are nowadays operated by several organizations worldwide.
Neutral buoyancy
The Neutral Buoyancy Laboratory (NBL) is an astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
training facility at the Sonny Carter Training Facility at the NASA Johnson Space Center in Houston, Texas. The NBL is a large indoor pool of water, the largest in the world, in which astronauts may perform simulated EVA tasks in preparation for space missions. The NBL contains full-sized mock-ups of the Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
cargo bay, flight payloads, and the International Space Station
The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...
(ISS).
The principle of neutral buoyancy
Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink (if the body's densi ...
is used to simulate the weightless environment of space. The suited astronauts are lowered into the pool using an overhead crane
An overhead crane, commonly called a bridge crane, is a type of crane found in industrial environments. An overhead crane consists of two parallel rails seated on longitudinal I-beams attached to opposite steel columns by means of brackets. ...
and their weight is adjusted by support divers so that they experience no buoyant force and no rotational moment about their center of mass. The suits worn in the NBL are down-rated from fully flight-rated EMU
The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus '' Dromaius''. The ...
suits like those in use on the space shuttle and International Space Station.
The NBL tank is in length, wide, and deep, and contains 6.2 million gallons (23.5 million litres) of water. Divers breathe nitrox while working in the tank.
Neutral buoyancy in a pool is not weightlessness
Weightlessness is the complete or near-complete absence of the sensation of weight. It is also termed zero gravity, zero G-force, or zero-G.
Weight is a measurement of the force on an object at rest in a relatively strong gravitational fie ...
, since the balance organs in the inner ear still sense the up-down direction of gravity. Also, there is a significant amount of drag
Drag or The Drag may refer to:
Places
* Drag, Norway, a village in Tysfjord municipality, Nordland, Norway
* ''Drág'', the Hungarian name for Dragu Commune in Sălaj County, Romania
* Drag (Austin, Texas), the portion of Guadalupe Street adj ...
presented by water. Generally, drag effects are minimized by doing tasks slowly in the water. Another difference between neutral buoyancy simulation in a pool and actual EVA during spaceflight is that the temperature of the pool and the lighting conditions are maintained constant.
Speculative or fictional mechanisms
In science fiction, artificial gravity (or cancellation of gravity) or "paragravity" is sometimes present in spacecraft that are neither rotating nor accelerating. At present, there is no confirmed technique as such that can simulate gravity other than actual mass or acceleration. There have been many claims over the years of such a device. Eugene Podkletnov
Eugene Podkletnov (russian: Евгений Подклетнов, Yevgeny Podkletnov) is a Russian ceramics engineer known for his claims made in the 1990s of designing and demonstrating gravity shielding devices consisting of rotating discs const ...
, a Russian engineer, has claimed since the early 1990s to have made such a device consisting of a spinning superconductor producing a powerful " gravitomagnetic field", but there has been no verification or even negative results from third parties. In 2006, a research group funded by ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (1 ...
claimed to have created a similar device that demonstrated positive results for the production of gravitomagnetism, although it produced only 0.0001 ''g''. This result has not been replicated.
See also
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References
External links
List of peer review papers on artificial gravity
TEDx talk about artificial gravity
Variable Gravity Research Facility (xGRF)
concept with tethered rotating satellites, perhaps a Bigelow expandable module and a spent upper stage
A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage ...
as a counterweight
{{DEFAULTSORT:Artificial Gravity
Gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the str ...
Gravity
Space colonization
Scientific speculation
Space medicine