Asked in Astronauts
Describe the conditions under which astronauts train weightness in space?
I'm uncertain what the question means. Astronauts do not normally 'train' while in space. They train in preparation for space. Assuming that is what the question means:
There are two ways astronauts train for weightlessness. Neither is satisfactory.
* They train it a place called the WIF or Water Immersion Facility. You can think of this as a swimming pool where the astronauts and the equipment they handle are made neutrally buoyant. That is, heavy or light material is attached so they neither float nor sink in water, but remain suspended in the water. The resistance of the water on movement and the fact that your internal organs still feel the pull of gravity limit it's value for simulating weightlessness in space. * They ride on an airplane that makes zero-g parabolic flights (visit link below). The airplane (called variously, the Vomit Comet, the Weightless Wonder, etc.) climes to a peak then allows itself to fall for about 30 seconds. When you are falling you are weightless, so this accurately simulates the weightlessness of space. But, but the short periods and the high forces when the plane pulls out of the fall make it of limited value for training.