[Ray Allan]

Both Soviet and American space programs adopted the neutral buoyancy tank method to train for EVA after Leonov's first spacewalk where his suit overinflated and almost didn't make back inside his spaceship and Eugene Cernan on the second US spacewalk during the Gemini 9 mission where he overexerted and overheated himself and was nearly killed. Since water training to simulate weightlessness was adopted, nearly all EVAs have had a 100 percent success rate.

Also the "Vomit Comet" aircraft are used to create brief periods of actual weightlessness by flying a special parabolic maneuver.