LIFE-SUPPORT SYSTEMS IN SPACE
WEIGHTLESSNES AND ARTIFICIAL GRAVITY
Weightlessness occurs when all forces applied to a person or object are uniformly distributed as in a uniform gravitational field, or when they are not acted by any force. In orbit and deep space, weightlessness occurs when an object or person is falling freely. Exposure to weightlessness conditions cause numerous deleterious effects on human health and significant health concerns: vertigo, nausea, headache, lethargy, skeletal and muscle reconditioning and atrophy, loss of bone mineral density, cardiac problems, lose of heart mass, cardiovascular changes, red blood cell loss, fluid redistribution and loss, weight loss, facial distortion, and changes of the immune system. There are physiologic problems of adaptation to microgravity conditions and of renewed adaptation to Earth-normal gravity conditions. Weightless environment in space is complicating all human activities and material handling as objects are floating in completely independent orbits.
It is necessary to generate artificial gravity sensation to resolve or reduce all or a major part of problems present in weightless conditions in Earth orbit and deep space and to design a kind of artificial gravity generators as a life support and habitation systems to enable sustainable exploration and colonization of space. Gravity sensation can be induced by the inertial reaction to the centripetal acceleration that acts on a body in circular motion. The most distinguished concept is the one of rotating torus or wheel-shaped habitat to produce artificial gravity by the centripetal force which always points toward the center of rotation causing objects to behave as if they had weight while inhabitants and objects keep moving in uniform circular motion. Effects of the centripetal force could be accepted as artificial or simulated gravity and the whole system can be seen as artificial gravity generator.
The idea of using rotation to create artificial gravity in space was introduced by Konstanin Tsiolkovsky in 1903. Hermann Oberth was the first to use the term space station for a wheel-shaped facility in 1923. By 1929, Hermann Noordung introduced concept of rotating wheel station and suggested it to be positioned in a geostationary orbit. Wernher von Braun and Willy Ley upgraded the idea in the 1950s, popularizing the concept of a spinning wheelshaped station to provide artificial one-third Earth gravity. In 1968 the film “2001: A Space Odyssey“ by Arthur C. Clarke and Stanley Kubrick described spin-generated artificial gravity aboard a space station and on a spaceship.