Weightlessness

Weightlessness is the complete or near-complete absence of the sensation of weight. This is also termed zero-g, although the more correct term is 'zero g-force'. It occurs in the absence of any contact forces upon objects including the human body.The myth that satellites remain in orbit because they have 'escaped Earth's gravity' is perpetuated further (and falsely) by almost universal misuse of the word 'zero gravity' to describe the free-falling conditions aboard orbiting space vehicles. Of course, this isn't true; gravity still exists in space. It keeps satellites from flying straight off into interstellar emptiness. What's missing is 'weight', the resistance of gravitational attraction by an anchored structure or a counterforce. Satellites stay in space because of their tremendous horizontal speed, which allows them—while being unavoidably pulled toward Earth by gravity—to fall 'over the horizon.' The ground's curved withdrawal along the Earth's round surface offsets the satellites' fall toward the ground. Speed, not position or lack of gravity, keeps satellites in orbit around the earth.'Jake Garn was sick, was pretty sick. I don't know whether we should tell stories like that. But anyway, Jake Garn, he has made a mark in the Astronaut Corps because he represents the maximum level of space sickness that anyone can ever attain, and so the mark of being totally sick and totally incompetent is one Garn. Most guys will get maybe to a tenth Garn, if that high. And within the Astronaut Corps, he forever will be remembered by that.' Weightlessness is the complete or near-complete absence of the sensation of weight. This is also termed zero-g, although the more correct term is 'zero g-force'. It occurs in the absence of any contact forces upon objects including the human body. Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's inertia by mechanical, non-gravitational forces- such as in a centrifuge, a rotating space station, or within an accelerating vehicle. When the gravitational field is non-uniform, a body in free fall experiences tidal effects and is not stress-free. Near a black hole, such tidal effects can be very strong. In the case of the Earth, the effects are minor, especially on objects of relatively small dimensions (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity, and it prevails in orbiting spacecraft.