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The Neutral Buoyancy Simulator was a neutral buoyancy pool located at NASA's George C. Marshall Space Flight Center (MSFC). Engineers and astronauts developed hardware and practiced procedures in this tank from its completion in 1968 through its decommissioning in 1997. Marshall recognized the need for underwater simulations of extra-vehicular activities (EVAs) and developed three successively larger tanks for the purpose. The Neutral Buoyancy Simulator contributed significantly to the American manned space program. Skylab, the Space Shuttle, Hubble Space Telescope, and the International Space Station have all benefited from the Neutral Buoyancy Simulator. Until Johnson Space Center constructed the Weightless Environment Test Facility in the mid-1970s, MSFC had the only NASA-owned test facility that allowed engineers and astronauts to become familiar with the dynamics of body motion under weightless conditions.〔 The water within the simulator was temperature controlled, continuously recirculated and filtered. Special systems were integrated into the tank for underwater audio and video, pressure-suit environmental control and emergency rescue and treatment. Life support was simultaneously provided by these systems for up to four pressure-suited subjects. Additional systems included data acquisition and recording, underwater lighting, special underwater pneumatic and electrical power operations of motor, valves, controls, and indicators that required for high fidelity and functional engineering mockups and trainers. == Principles of operation == Neutral buoyancy simulates the weightless environment of space.〔 First equipment is lowered into the pool using an overhead crane. Suited astronauts then get in the tank and support divers add weight to the astronauts so that they experience no buoyant force and no rotational moment about their center of mass. One downside of using neutral buoyancy to simulate microgravity is the significant amount of drag presented by water. Generally, drag effects are minimized by doing tasks slowly in the water. Another downside of neutral buoyancy simulation is that astronauts are not weightless ''within'' their suits, thus, precise suit sizing is critical. == Origins and first tank == NASA has flown zero-g flights on various aircraft for many years. In 1959, Project Mercury astronauts trained in a C-131 Samaritan aircraft, which was dubbed the "Vomit Comet". Airplane weightlessness is limited to 25 seconds at a time, which hampers efforts to practice EVAs which might last hours. Prior to May 1960, NASA recognized the possibility of underwater neutral buoyancy simulations and began testing its efficacy. NASA engaged Environmental Research Associates of Baltimore to try neutral buoyancy simulations first in a pool near Langley Research Center. Visitors and other issues disturbed those efforts, and they moved the operation to McDonogh School where Scott Carpenter was the first astronaut to participate suited. Then, after difficult EVAs through Gemini 11 in mid-September 1966, the Manned Spacecraft Center fully understood the importance of testing procedures underwater and sent the Gemini 12 crew to train at McDonogh.〔Levine, Raphael B.: Null-Gravity Simulation. Paper presented at the 3lst Annual Meeting of the Aerospace Medical Association, May 9-11, 1960.〕〔Otto F. Trout, Jr., Harry L. Loats, Jr., and G. Samuel Mattingly ("NASA Contract NAS1-4059 with supplemental agreements" ), January 1966〕 Meanwhile, MSFC was looking ahead to the Apollo Applications Program which would involve EVAs to convert a mostly-empty S-IVB rocket stage into a space station, and the people designing the hardware needed a thorough understanding of the challenges of weightlessness. Charlie Cooper at MSFC theorized that neutral buoyancy exercises could help with EVA planning while he was reviewing film of the Gemini 4 EVA. He and Charles D. Stocks pursued the idea with a couple of NASA scuba suits and an diameter, deep pool which had been previously used for forming metal parts explosively. November 1965 tests included removal of the ST-124 and a J-2 engine propellant utilization valve - early steps in a nascent Skylab mission, then called S-IVB orbital workshop.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Neutral Buoyancy Simulator」の詳細全文を読む スポンサード リンク
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