Artificial Gravity: Artificial gravity is the emulation in outer space or free-fall of the effects of gravity felt on a planetary surface. It can be achieved by designing for the use of some different force, such as the centrifugal force that is felt within a rotating space habitat. Artificial gravity is desirable for long-term space travel or habitation, for ease of mobility and to avoid the adverse health effects of weightlessness.
Requirement for gravity
Without g-force, space adaptation syndrome occurs on animals. Many adaptations occur over a few days, but over a long period of time bone density decreases, and some of this decrease may be permanent. The minimum g-force required to avoid bone loss is not known- all current experience is with g-forces of 1g (on the surface of the Earth) or 0g in orbit. There has been insufficient time spent on the moon to determine whether lunar gravity is sufficient.
A similar effect occurs with people who are bedridden or wheelchair-bound.
A limited amount of experimentation has been done with chickens experiencing high g-force over long periods in centrifuges on the Earth.
Artificial gravity represents a different and integrated approach to addressing the detrimental effects of microgravity, or even reduced gravity, on the human body. Artificial gravity mimics our natural 1-g environment. All body systems are challenged simultaneously by its application, not simply one physiological system at a time. Artificial gravity will not be a panacea for addressing all risks associated with human spaceflight. Obviously it cannot solve the critical problems associated with radiation exposure, isolation, confinement, and life support systems failures. However, it offers significant promise as an effective, efficient multi-system countermeasure against the physiological deconditioning effects associated with prolonged exposure to weightlessness. The appropriate application of artificial gravity might serve to address virtually all of the risks associated with bone loss, cardiovascular deconditioning, muscle weakening, neurovestibular disturbances, space anemia, and immune system deficiency.