Artificial gravity is a simulation of gravity in outer space or freefall. Artificial gravity is desirable for long-term space travel for ease of mobility and to avoid the adverse health effects of weightlessness.
Artificial gravity could be created in two ways: rotation or acceleration. The spacecraft could rotate so that anything inside will be forced toward the outside by centrifugal force. It would take a large amount of energy to rotate a spacecraft at the appropriate speed. The spacecraft could also continuously accelerate in a straight line, forcing objects inside the spacecraft in the opposite direction of the direction of acceleration.
In an Earth orbit a small artificial gravity can be obtained from the tidal force, by two spacecrafts above each other (or one spacecraft and another mass), connected by a tether. See also Tidal stabilization.
Artificial gravity by rotation has the following side-effects:
- Coriolis forces
- gravity gradients across the spacecraft
- weight changes with angular movement
In the Mars Gravity Biosatellite mission the effect on mammals will be studied of artificial gravity of 0.38 g (Mars gravity), by rotation (34 rpm, radius of ca. 30 cm). Fifteen mice will orbit Earth for five weeks and land alive.
Fiction
The film poster from the original release of
2001: A Space Odyssey features a rotating space station. The people would be walking inside the circle, their feet toward the exterior and their head toward the center.
In the movie 2001: A Space Odyssey a rotating spaceship provides artificial gravity.
Also, in science fiction artificial gravity is sometimes present in spacecraft that are neither rotating nor accelerating. It is probably not possible to create artificial gravity of this type, although a similar effect can be created through diamagnetism, but it would involve avoiding any non-diamagnetic materials near the strong magnetic field required for diamagnetism to be evident.
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