I have read somewhere that to-be astronauts are trained on earth to be deft enough when they are in space which has zero gravity. How do we create a zero gravity situation on earth? On earth even if you are in a vacuum you still experience the force of gravity, so exactly how do we engineer such a situation which actually defies gravity on earth itself?
There are two methods which are used:
- Aircraft can fly on a trajectory that will simulate zero gravity for a few seconds, usually around 30. This is used for most short term zero gravity tests. It is commonly known as the "vomit comet", especially the earlier versions.
- Underwater testing can be done, in a neutral buoyancy lab. Basically, you make it so you weigh as much as the water you displace does, making it so you "float" in zero gravity. If you pushed away from something, you would continue to move (Although being in water, you have drag and swimming that could move you as well)
Both are approximations, but they do work well enough to do something at least.