A neutral buoyancy pool or neutral buoyancy tank is a pool of water in which neutral buoyancy is used to train astronauts for extravehicular activity and the development of procedures. These pools began to be used in the 1960s and were initially just recreational swimming pools; dedicated facilities would later be built.
Prior to May 1960, NASA recognized the possibility of underwater neutral buoyancy simulations, and began testing their efficacy. NASA engaged Environmental Research Associates, a company based in Baltimore, to try neutral buoyancy simulations first in a pool near Langley Research Center. Visitors and other issues disturbed those efforts, so they moved the operation to a swimming pool at the McDonogh School in Maryland, 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 (later renamed the Johnson Space Center) fully understood the importance of testing procedures underwater, and sent the Gemini 12 crew to train at McDonogh. [1] [2] [3] [4]
The Neutral Buoyancy Simulator, located at the Marshall Spaceflight Center in Alabama, operated from 1967 through 1997. [5] The facility had three tanks. The first had a diameter of 2.4 meters (8 ft) and a depth of 2.4 meters (8 ft). The second tank was built in 1966 and had a diameter of 7.6 meters (25 ft) and a depth of 4.6 meters (15 ft). A third tank was added around 1968 for Skylab and other planned projects; it had a diameter of 23 meters (75 ft) and was 12 meters (40 ft) deep.
Training in the NBS decreased when the Johnson Space Center opened its own neutral buoyancy pool in 1980, it eventually was closed in 1997. [5]
WIF was used for the Gemini and Apollo programs and was located in Building 5 at the Johnson Space Center in Houston, Texas.
The pool had a diameter of 7.6 meters (25 ft) and a depth of 4.9 meters (16 ft).
WETF, in operation from 1980 through 1998, was located in Building 29 at the Johnson Space Center in Houston, Texas. [5] [6] The dimensions of the pool were 24 meters (78 ft) by 10 meters (33 ft), with a depth of 7.6 meters (25 ft). [6]
In the late 1980s, NASA began to consider replacing the WETF, which was too small to hold useful mock-ups of many of the space station components planned for Space Station Freedom, which later morphed into the International Space Station. NASA purchased the then-processing facility from McDonnell Douglas in the early 1990s, and began refitting it as a neutral-buoyancy training center in 1994 with construction ending in December 1995. The NBL began operation in 1997. [7]
The NBL is located at the Sonny Carter Training Facility, near the Johnson Space Center in Houston. [8] The pool's dimensions are 62 meters (202 ft) by 31 meters (102 ft), with a depth of 12 meters (40 ft). [8]
Following the Voskhod 2 mission, a group at the Gagarin Cosmonaut Training Center (GCTC) proposed training for EVAs in a pool. [9] In September 1969, GCTC created a working group to further study the idea, and some experiments were performed in their swimming pool near the end of that year. [9] In 1970, cosmonauts Andriyan Nikolayev and Vitaly Sevastyanov visited NASA's new 23 meters (75 ft)-diameter pool at Marshall. [9] Sevastyanov was even allowed to don a training suit and enter the pool. [9] Following the visit, further interest in a similar facility began to grow within the Soviet space program. [9] In November 1973, it was officially decided to construct a dedicated pool; until then, the center's swimming pool continued to be used. [9]
Hydro Lab was completed in early 1980; the pool there has a diameter of 23 meters (75 ft) and a depth of 12 meters (39 ft). [9] [10]
The Chinese NBF [11] is located at the China Astronaut Research and Training Center in Beijing. It has a diameter of 23 meters (75 ft) and depth of 10 meters (33 ft). [12] Construction began in 2005 and was completed in November 2007. [13] Operations began in 2008. [13]
The European NBF is located at the European Astronaut Center in Cologne, Germany. [14] It has an octagonal shape and dimensions of 22 meters (72 ft) by 17 meters (56 ft), with a depth of 10 meters (33 ft). [15] Operations began in 2002. [16]
WETS was located at the Tsukuba Space Center in Ibaraki, Japan. [5] It opened in 1997 and closed in 2011 due to extensive earthquake damage. [5] The pool had a diameter of 16 meters (52 ft), and depth of 10.5 meters (34 ft). [17]
The NBRF is located at the University of Maryland in the US. [18] The pool has a diameter of 15 meters (50 ft) and a depth of 7.6 meters (25 ft). [18] It was built in 1992, and is the only neutral buoyancy facility on a college campus. [18] The NBRF is part of the Space Systems Laboratory (SSL) which was originally located at the Massachusetts Institute of Technology (MIT). [18] It split from MIT when the SSL was awarded a grant from NASA to build a dedicated neutral buoyancy pool. [18] Since there was not enough space at MIT for the pool, it was decided to move the SSL to the University of Maryland. [18]
The Underwater Astronaut Trainer (UAT) is located at the United States Space and Rocket Center, home of Space Camp and Space Academy, in Huntsville, AL. 30 feet wide and 24 feet deep, it was designed by Homer Hickam, a NASA engineer famous for writing Rocket Boys adapted into the film October Sky. Opened in 1986, it is still active.[ citation needed ]
During training exercises, neutral-buoyancy diving is used to simulate the weightlessness of space travel. To achieve this effect, suited astronauts or pieces of equipment are lowered into the pool using an overhead crane and then weighted in the water by support divers so that they experience minimal buoyant force and minimal rotational moment about their center of mass. [19] The suits worn by trainees in the NBL are down-rated from fully flight-rated EMU suits like those in use on the Space Shuttle and International Space Station. Divers breathe nitrox while working in the tank. [20] [21]
One disadvantage of neutral-buoyancy diving as a simulation of microgravity is the significant amount of drag created by the water. [22] This makes it difficult to set an object in motion, and difficult to keep it in motion. It also makes it easier to keep the object stationary. This effect is the opposite of what is experienced in space, where it is easy to set an object in motion, but very difficult to keep it still. 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, meaning that as divers tilt their suits they are pressed against whatever inside surface is facing down. This can be uncomfortable in certain orientations, such as heads-down. Thus, precise suit sizing is critical.
The Lyndon B. Johnson Space Center (JSC) is NASA's center for human spaceflight, where human spaceflight training, research, and flight control are conducted. It was renamed in honor of the late US president and Texas native, Lyndon B. Johnson, by an act of the United States Senate on February 19, 1973.
A diving weighting system is ballast weight added to a diver or diving equipment to counteract excess buoyancy. They may be used by divers or on equipment such as diving bells, submersibles or camera housings.
Michael Landon Gernhardt is a NASA astronaut and manager of the Environmental Physiology Laboratory, and principal investigator of the Prebreathe Reduction Program (PRP) at the Lyndon B. Johnson Space Center.
Artificial gravity is the creation of an inertial force that mimics the effects of a gravitational force, usually by rotation. Artificial gravity, or rotational gravity, is thus the appearance of a centrifugal force in a rotating frame of reference, as opposed to the force experienced in linear acceleration, which by the equivalence principle is indistinguishable from gravity. In a more general sense, "artificial gravity" may also refer to the effect of linear acceleration, e.g. by means of a rocket engine.
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface air supply. The name "scuba", an acronym for "Self-Contained Underwater Breathing Apparatus", was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long and/or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the likelihood and effects of nitrogen narcosis during deeper dives.
Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink or rise. An object that has neutral buoyancy will neither sink nor rise.
The Space Systems Laboratory (SSL) is part of the Aerospace Engineering Department and A. James Clark School of Engineering at the University of Maryland in College Park, Maryland. The Space Systems Laboratory is centered on the Neutral Buoyancy Research Facility, a 50-foot-diameter (15 m), 25-foot-deep (7.6 m) neutral buoyancy pool used to simulate the microgravity environment of space. The only such facility housed at a university, Maryland's neutral buoyancy tank is used for undergraduate and graduate research at the Space Systems Lab. Research in Space Systems emphasizes space robotics, human factors, applications of artificial intelligence and the underlying fundamentals of space simulation. There are currently five robots being tested, including Ranger, a four-armed satellite repair robot, and SCAMP, a six-degree of freedom free-flying underwater camera platform. Ranger was funded by NASA starting in 1992, and was to be a technological demonstration of orbital satellite servicing. NASA was never able to manifest it for launch and the program was defunded circa 2006. For example, Ranger development work at the SSL continues, albeit at a slower pace; Ranger was used to demonstrate robotic servicing techniques for NASA's proposed robotic Hubble Servicing Mission.
The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility, near the Johnson Space Center in Houston, Texas. The NBL's main feature is a large indoor pool of water, in which astronauts may perform simulated EVA tasks in preparation for upcoming missions. Trainees wear suits designed to provide neutral buoyancy to simulate the microgravity that astronauts would experience during spaceflight.
The Experimental Assembly of Structures in EVA and the Assembly Concept for Construction of Erectable Space Structures, or EASE/ACCESS, were a pair of space shuttle flight experiments that were performed on STS-61-B, on November 29 and December 1, 1985. The purpose of the experiments was to study how quickly astronauts would become proficient at assembling space structures during extravehicular activity, and how quickly they would become fatigued, and to explore various construction and maintenance techniques. In particular, researchers studied the applied moments of inertia arising in the manual assembly of a large space structure.
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 crewed 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.
Weightlessness is the complete or near-complete absence of the sensation of weight. It is also termed zero G-force or zero-G.
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.
Astronaut training describes the complex process of preparing astronauts in regions around the world for their space missions before, during and after the flight, which includes medical tests, physical training, extra-vehicular activity (EVA) training, procedure training, rehabilitation process, as well as training on experiments they will accomplish during their stay in space.
Skylab II was a space station concept proposed in 2013 by the Advanced Concepts Office of NASA Marshall Space Flight Center, to be located at the Earth-Moon L2 Lagrangian point. Proposed by NASA contractor Brand Griffin, Skylab II would have been constructed as a "wet workshop" using a spent upper-stage hydrogen fuel tank from the Space Launch System (SLS), much as the Skylab was originally planned to be built "wet" from the spent bipropellant tanks of the Saturn S-IVB upper stage. If constructed, Skylab II would have been the first crewed outpost located beyond the orbit of the Moon.
The trim of a diver is the orientation of the body in the water, determined by posture and the distribution of weight and volume along the body and equipment, as well as by any other forces acting on the diver. Both static trim and its stability affect the convenience and safety of the diver while under water and at the surface. Midwater trim is usually considered at approximately neutral buoyancy for a swimming scuba diver, and neutral buoyancy is necessary for efficient maneuvering at constant depth, but surface trim may be at significant positive buoyancy to keep the head above water.
Scuba skills are skills required to dive safely using self-contained underwater breathing apparatus. Most of these skills are relevant to both open-circuit scuba and rebreather scuba, and many are also relevant to surface-supplied diving. Certain scuba skills, which are critical to divers' safety, may require more practice than is provided during standard recreational training.
The Valsalva device is a device used in spacesuits, some full face diving masks and diving helmets to allow astronauts and commercial divers to equalize the pressure in their ears by performing the Valsalva maneuver inside the suit without using their hands to block their nose. Astronaut Drew Feustel has described it as "a spongy device called a Valsalva that is typically used to block the nose in case a pressure readjustment is needed."
Hervé Stevenin is a European aquanaut leading ESA Neutral Buoyancy Facility Operations and the EVA Training Unit at the European Astronaut Centre (EAC) in Cologne, Germany. He served as an aquanaut on the NASA Extreme Environment Mission Operations 19 crew.
Blue Abyss is a research pool planned for construction in Cornwall, England, United Kingdom. It will be 50 metres (160 ft) deep with volume of approximately 42,000 cubic metres (1,500,000 cu ft), making it the world's second deepest pool after the Deep Dive Dubai.
Mary Helen Johnston, later also Mary Helen McCay, is an American scientist and former astronaut. Working with NASA as an engineer in the 1960s and '70s, Johnston aspired to be an astronaut; she unsuccessfully applied in 1980 before becoming a payload specialist in 1983. Johnston retired from NASA in 1986 without having gone to space. She is a professor at Florida Institute of Technology.
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