Neutral buoyancy simulation as a training aid

Neutral buoyancy simulation with astronauts immersed in a neutral buoyancy pool, in pressure suits, can help to prepare astronauts for the difficult task of working while outside a spacecraft in an apparently weightless environment.

Extra-vehicular activity (EVA), working outside the space vehicle, was one of the goals of the Gemini Program during the 1960s. The astronauts were trained in the “zero gravity” condition by flying a parabolic trajectory in an aircraft that caused reduced gravity for thirty second intervals.

The Russian cosmonaut Alexey Leonov was the first to egress his vehicle while travelling in orbit above the earth. Shortly after, Ed White, Gemini IV, was the first American astronaut to egress a vehicle while in space. These were demonstrations of a capability to get out of and back into the vehicle but included no EVA tasks. The next three flights to demonstrate an EVA capability were Gemini IX-A, X, and XI. Each of these flights exposed problems with performance of EVA tasks. Working in pressure suits while in the constant weightlessness of orbital spaceflight was more complex and difficult than had been anticipated. NASA determined that training for EVA tasks required further development.

In July 1966 the Gemini Program joined in a NASA Langley Research Center contract to include an evaluation of Gemini EVA tasks. The contractor, Environmental Research Associates of Randallstown, MD had already begun developing a neutral buoyancy simulation capability in 1964. This capability for pressure suited subjects was initially developed in 1964 by utilizing an indoor swimming pool at a private school (McDonogh School near Baltimore). Initially, these early underwater simulations were simply designed to test the ability of subjects to move about mock-up airlocks and weights were not attached to the subjects. Quickly, Environmental Research Associates' submerged testing evolved into proper neutral buoyancy simulation, featuring weighted subjects and numerous safety divers on hand during given sessions.

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