To ensure that these activities can take place as originally planned, it is necessary to evaluate the EVA procedures, tools, and support equipment in advance. EVA weightless environment simulation tests are conducted to support these evaluations. The fourth EVA weightless environment simulation test was conducted from August 24 to October 9, 1998. The right figure shows a photograph of an astronaut wearing a space suit used in the underwater tests. Astronauts practice EVAs in a simulated weightless space environment created by neutral buoyancy underwater in order to confirm whether EVA planning is correct or not.
Several divers surround the astronaut to support the astronaut's activities in the underwater test.
In addition, another group of divers prepares for the tests to ensure that things go smoothly. The validity of EVA procedures cannot be evaluated without actual performance. The first hurdle was mastering the necessary skills for underwater duties. These skills included diving regulations, physiological changes under water, and using underwater equipment. This is simply a certificate, which does not involve actual underwater testing.