This is the popular term for the strange condition that you experience when you venture into space, in which the body appears not to have any weight. Another term for it is zero-g, meaning no gravity. 'Zero-g' is not a good term because gravity still exists in orbit, pulling the body towards the ground. However, because you are travelling around the Earth at very high speed (some 28,000 km/h), the amount you fall towards the Earth is balanced by the amount the Earth curves away beneath you. So in effect you remain the same height above the Earth. This state, in which you are 'falling around the Earth' is termed free fall. Weightlessness affects everything you do in orbit - moving about, eating, drinking, going to the lavatory, and working with tools. Liquids won't pour, for example, so you can't drink them from a glass - you have to suck them up. Space lavatories are flushed with a stream of air to remove body wastes. Prolonged weightlessness can have a debilitating effect on the body, but this can be minimized by taking regular exercise. The study of the effects of the space environment on the body is called space medicine. Long-stay Soviet cosmonauts have emphatically demonstrated that human beings can remain in space for a year or more without coming to any harm, which bodes well for Man's future in space.
