Neutral buoyancy diver maintains neutral buoyancy by continuous correction, usually by controlled breathing, as neutral buoyancy is an unstable condition for a compressible object in a liquid. The mathematician Archimedes discovered much of how buoyancy works more than 2000 years ago. In his research, Archimedes discovered that an object is buoyed up by a force equal to the weight of the water displaced by the object. In other words, an inflatable boat that displaces 100 pounds (45 kilograms) of water is buoyed up by that same weight of support. An object that floats in the water is known as being "positively" buoyant.
Neutral buoyancy simulation as a training aid simulation can advise as to how realistic is the task performance and recommend modifications. Learning and rehearsing an EVA task in neutral buoyancy gives an astronaut or EVA specialist confidence that the planned task may be accomplished. The timeline developed for task performance is similar to the time required in EVA. In general, it is considered that a task performed and practiced in neutral buoyancy simulation can also be performed in EVA. Neutral buoyancy, properly planned and conducted, works because it is a realistic simulation of the physical requirements of performing a task in EVA. The other major method used