Microgravity refers to the state of almost free fall, ie from near zero gravity. This is achieved integration into an orbit spacecraft, but for example also in a drop tower or a parabolic flight.
The achievable weightlessness in a spacecraft is not perfect. Among the reasons that the gravity is still being felt, include:
- The strength of the gravitational field of the earth decreases with increasing distance from the Earth for every three meters to one millionth of a from ( this rule of thumb applies to the near-Earth region up to a few hundred kilometers altitude ). Therefore, the gravitational difference is within the spacecraft volume thus already in the measurable range.
- The erdfernere part of a body in orbit experiences a greater centrifugal force than the erdnähere part.
- At the height of the orbit, the atmosphere is very thin, but is there air, the air resistance leads to a deceleration of the spacecraft by friction.
The tidal power, which is caused by the first two points, is directed away from the earth, when the body is above the center of gravity of the spacecraft, in the remaining part of the spacecraft to act downwardly to the ground. The last point causes a forward force.