Buoyancy Tank

[Arnaude Kubiak]

The NBRF is one of two currently operating neutral buoyancy tanks in the US. It is the only one in the world located on a college campus, and the only one dedicated to basic research. Neutral buoyancy is one of the primary means of simulating the microgravity environment of space; while the NBRF was originally developed to support NASA studies of orbital operations, it is also actively used for underwater robotics and both human and robotic operations in simulated lunar and Mars gravity. Related research in the Space Systems Laboratory (SSL) emphasizes space, undersea, and medical rehabilitation robotics; space human factors, including bioinstrumentation and advanced space suit design and testing; human-robot collaboration technologies; and the underlying fundamentals of space simulation.

The neutral buoyancy tank is 50 feet across, 25 feet deep, and holds 367,000 gallons of water. Water temperature is maintained at 88F for consistency of buoyancy and comfort of test support divers, and is specially filtered for maximum visual clarity.

The facility allows external access for underwater test hardware up to 15 feet on a side and up to 4000 pounds in weight. Complete SCUBA diver support facilities include two locker rooms, air compressors for filling SCUBA bottles, and both underwater speakers and bidirectional underwater communications system. A secure storage facility for underwater test hardware is located outside the NBRF for hardware which will not be damaged by exposure to the elements.

There are currently six robots operational in the NBRF, including two generations of Ranger, a four-armed satellite repair robot; two SCAMP vehicles and EUCLID, all 6 degree of freedom free-flying underwater vehicles used as camera platforms and for advanced control algorithm development; and SAMURAI, a 6000-meter rated deep ocean electrical dexterous manipulator for autonomous underwater operations. The NBRF is equipped with a 16-camera Qualisys motion tracking system capable of providing measurement of the location and velocity of an essentially unlimited number of optical targets at submillimeter accuracy and less than 100 msec sample times. The robotic manipulator systems are also capable of operation in the laboratory environment, allowing simplified checkout and correlation between underwater and laboratory simulations.

The SSL has developed two series of human-rated suits for simulation of extravehicular activity underwater. The MX-2 system is a full pressure suit, operating at 3.5 psid and providing a dry environment for the wearer with high fidelity to flight-rated pressure suits. This suit has been equipped with a variety of bioinstrumentation for measuring body motions and metabolic workload, as well as advanced controls and displays for immersive virtual reality presentations as part of the underwater simulation. A parallel series of space suit simulators provide a lower-fidelity experience of suited operations, but provide low-cost simulations without excessive training requirements for the test subject. Wearers of the MX-C/MX-D series of suit simulators are immersed in water, and effectively supplied by conventional scuba equipment within the suit envelope. Other human test systems available at the NBRF include a body harness for body segment parameter ballasting for realistic simulation of partial gravity environments such as the moon and Mars, and an underwater treadmill for studying gaits and workloads.

A small but very well-equipped machine shop on-site is used to fabricate and repair test equipment, with both manual and computer guided mills and lathes, sheet metal forming capabilities, and TIG welding equipment. The SSL also has access to rapid prototyping capabilities and the well-equipped machine shop of the Clark School of Engineering.

The NBRF control room is used for conducting tests in the neutral buoyancy tank. The control room has four general-purpose workstations that are used to control robots underwater through Space Shuttle-style hand controllers or a virtual reality interface, as well as providing multiple user-selectable video views from cameras in and above the tank. A multichannel communications system allows test conductors to talk with divers underwater, with personnel throughout the NBRF, and with other sites across the country through the Internet and satellite links. The control room also houses a complete video control and editing suite, and is capable of sourcing live video feeds for broadcast purposes.

Basic facility rental is $2500/day, which includes Space Systems Laboratory personnel supporting surface activities and conducting underwater test support. Dive personnel from outside entities can be certified to dive in support of test operations, but this requires extensive training and certification as well as physician health exams. Organizations interested in supplying dive personnel should contact the NBRF no less than two months prior to testing.

Many boats have built-in buoyancy tanks. Our 1999 Gemini catamaran has one in the bow and stern of each hull. Theoretically, they contain enough air to keep the boat at least awash if the hull was holed.

I just bought a 1999 Gemini 105M. I opened up the stern buoyancy tanks to inspect them. I found both tanks have about a one inch hole drilled into the bow side of the tank wall right along flush with the bottom of the tank. This is my question: seeing how they are identical, I have to think it was intentional. since they are at the bottom of the tanks then the tanks can still hold air, though it would be less displacement since the air will be under pressure. I did find standing water in both tanks. So bottom line, ARE THE HOLE IN THE TANKS BY DESIGN? ARE THE HOLES SO I CAN SEE IF WATER HAS LEAKED THROUGH INTO THE FRESH WATER HOLDING TANK SPACES?

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]

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]

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 university 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 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.[19]

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