Technology | Diving | Aquarius

The Aquarius Underwater Laboratory: America's "Inner Space" Station

Aquarius Underwater Laboratory Virtual Visit: See where scientist live and work underwater. Experience a Aquanauts view from inside the Aquarius main viewport. (Quicktime, 5.8 Mb.)

The Aquarius is the only undersea laboratory dedicated to marine science operating in the world. Owned by the National Oceanic and Atmospheric Administration (NOAA) and managed by the University of North Carolina at Wilmington (UNCW), Aquarius operates 4.5 kilometers offshore of Key Largo, Florida. The underwater laboratory is deployed next to deep coral reefs, 20 meters beneath the surface. Aquarius provides life support systems that allow scientists to live and work underwater, in reasonably comfortable living quarters, with sophisticated research capabilities.

Aquarius was originally conceived and funded by NOAA's National Undersea Research Program (NURP) in the mid 1980s. The underwater laboratory was built by Victoria Machine Works in 1986-87. Initial deployment was in the U.S. Virgin Islands where 13 missions were conducted before Hurricane Hugo struck in 1989, and devastated St. Croix. Aquarius was retrieved from the seafloor in 1990 and was moved to North Carolina where it was refurbished under the direction of the University of North Carolina at Wilmington (UNCW). In 1993, the laboratory was redeployed in the Florida Keys National Marine Sanctuary, and supported 22 missions during the next three years. In 1996, Aquarius was recovered, and refurbished again. Many improvements were made to the system including construction of a semi-autonomous life support buoy that replaced a 17 by 34-meter life support barge. Aquarius was redeployed in 1997 and operations resumed in 1998.

The Aquarius System

The fully equipped underwater laboratory includes several components. The Aquarius “habitat” module is an 82-ton double-lock pressure vessel that measures approximately 14-meters long by 3-meters in diameter. Scientists live and work inside the habitat when they are not diving outside on the reefs. Entry is through the 20-m3 wet porch, which contains an open moon pool, dive equipment storage areas, hot water heater and shower. There are two main compartments in the Aquarius module. The 14-m3 "entry lock," contains bench space for computers and experiments, power equipment, life support controls, small viewports and bathroom facilities. The largest living space is the 40-m3 "main lock." It includes berths for a six-person crew, computer work stations, two large viewports, kitchen facilities that include a microwave, instant hot water dispenser, refrigerator, sink, dining and work areas. The main lock also contains life support controls, so both the entry and main locks can be independently pressurized.

The Aquarius baseplate is a 116-ton structure that provides a stable and level support base for the habitat. Each of the four legs contains 25 tons of lead ballast. The legs have seven feet of adjustment for leveling in variable seafloor terrain through the use of hydraulically-driven screw jacks. The habitat and baseplate were designed to survive severe storm conditions and have successfully weathered hurricanes in both the Caribbean and Florida.

The Life Support Buoy (LSB) is a 10-meter diameter buoy that was provided by NOAA's National Data Buoy Center. The LSB is maintained above Aquarius on a five-point mooring using 2 and 5/8 inch diameter double-braided nylon lines connected to approximately 1.5-meter diameter spring buoys. Mooring plates were installed with anchor bolts grouted 1.2-meters into the seafloor. The LSB includes a communication tower and over 70-square meters of inside work space. Inside are two diesel-powered 40 kW generators, two air compressors capable of 18.7 cfm (cubic feet per minute) output for filling air flasks, VHF radios, a cell phone, and a microwave broadcasting system. The LSB is linked to Aquarius by a three-inch diameter 42-meter unitized umbilical, which contains hoses that supply air from the compressors and oxygen from storage flasks, power lines from the generators, and 2 coaxial cables and 12 twisted pair wires for data and communications. The microwave telemetry system provides reliable audio, video, and data transmission between Aquarius and shore using "Wave Wireless Networking." Wave Wireless is a telecommunications and data communications manufacturer, and the specific system used is their SPEEDLAN 10ptp wireless link. The SPEEDLAN 10ptp is a 10-Mbps (megabytes per second) wireless point-to-point bridge that provides a secure wireless connection between Aquarius, the LSB, and shore. System upgrades are planned to increase bandwidth for improved video and voice communications that will support new broadcast and education programs.

A shore-based Mission Control center is located in Key Largo, approximately 12 kilometers from Aquarius, and includes a specially designed "watch desk" with computers and communication equipment linked to Aquarius via wireless telemetry. Also located on shore are: docks for the program's boats; office space; storage and work rooms for dive gear and equipment; an electronics shop; a six-person, dual-lock decompression chamber for emergency evacuation of Aquarius; two laboratories; and living accommodations for on-duty staff and visiting scientists.

The Advantages of Saturation Diving

Aquarius scientists escape the limitations of conventional surface-based scuba diving through saturation diving. Instead of coming to the surface after diving, scientists who use Aquarius return directly to the undersea laboratory. As long as the Aquanauts don't go back to the surface they can use special dive tables to greatly increase their bottom time - to nearly ten times over what they typically have using conventional surface-based diving techniques. At the end of each mission, aquanauts go through a 17-hour "decompression," where the pressure inside Aquarius is slowly reduced from ambient (the pressure at the working depth of Aquarius is 2.5 times surface pressure, or nearly 44 pounds per square inch) back to surface pressure (14.7 pounds per square inch). At the end of decompression the aquanauts "blow down" back to ambient depth in the entry lock, are met by ascent divers in the wet porch, and are escorted to the surface where they are picked up by boats and returned to shore.

Additional advantages provided by the Aquarius saturation system include the sophisticated power and communication capabilities of the habitat. Scientists also have email, telephone, and video conferencing capability to anywhere in the world.

Scientists who study coral reefs need to work underwater. But bottom time is not the only limitation, cost is also important. The cost of running Aquarius compared to surface-based operations provides an interesting contrast. Conducting research on or under the ocean is expensive. Bottom time conversions from saturation missions to surface-based programs suggest that it would take at least 60 -70 days to match the same bottom time as a ten-day saturation mission. Sixty days in the field with a team of four divers can approach $70,000 ($900/day for a boat and dive support, $120 day per diem for four people, and $120/day hotel expenses for two rooms.) Salary costs are not included in this calculation, but if considered would substantially increase the costs for surface based diving. Further, at the depths worked from Aquarius, surface-based diving is more rigorous than saturation diving. On a day-to-day basis, four divers could not possibly work more than 6 days without at least one day off, and over the course of several weeks additional time off is necessary. Larger dive teams could get around this problem, but costs would also increase. Repetitive deep diving schedules also expose divers to greater risk of decompression sickness than saturation diving.

So, how does Aquarius compare? One way to draw a comparison is to contrast the daily cost of Aquarius operations with the above surface-based cost estimates - assuming that the work could even be conducted from the surface, which in many cases is not possible. Ten days in Aquarius costs $100,000, or about $30,000 more than a surface-based project. This is not insignificant. However, few academic scientists have 60 days available to spend in the field, so getting a lot of work done in a short amount of time is another beneficial aspect of the Aquarius program.

Aquarius Science Results

Aquarius supports scientists in their efforts to better understand our oceans and coastal resources. An open and competitive peer-review process is used to select proposals that are submitted to the program on an annual basis. Over the course of almost 50 missions more than 200 scientists participated directly in the program, representing over 90 organizations including universities from across the U.S. and several foreign countries.

Aquarius scientists work to understand our changing ocean and the condition of coral reefs. Unfortunately, coral reefs are threatened worldwide by increasing amounts of pollution, overharvesting of fisheries, disease, and global climate change. Science achievements from Aquarius include discoveries related to the damaging effects of ultraviolet light on coral reefs, geological studies that use fossil reefs to better understand the significance of present-day changes in coral reefs, research that is rewriting the book on how corals feed, water quality studies that evaluate sources of pollution, and long-term studies of reefs to help distinguish between changes caused by natural system variability and humans (due to pollution and overharvesting).

Diving Into the Future

The evolution of Aquarius from substantial shore support, first using a mobile support barge and then the LSB, points toward even more autonomous operations in the future. For example, air storage banks located on the bottom, sufficient to support an entire mission, would eliminate the need for compressors now located in the LSB. Innovations in carbon dioxide scrubbing systems have already been tested in Aquarius. Modular construction of new habitat systems would allow for easier deployments and custom configurations based on individual site-based needs. And power systems located underwater, rather than from surface-based generators like the LSB, may soon be possible. Ultimately, only a communications buoy on the surface might give any hint of human habitation below. All of this points to increased system mobility, greater depth capability, and less surface support during missions, without sacrificing aquanaut safety.

The next generation of underwater laboratories will build on the successes of Aquarius, but challenges exist to provide even more cost-effective and flexible operations. A national debate is also underway regarding the use of remotely operated vehicles to replace human exploration and presence underwater. Arguments for machines to replace humans are based on considerations of cost and safety. However, programs like Aquarius and manned submersibles satisfy an essential element of the human spirit that cannot be met by robots. Further, human eyes still exceed the capabilities of cameras, and the creative potential of our brains to observe, explore, understand, and solve problems cannot be matched by computers. Human exploration in the extreme environments of the sea and outer space has captured the attention and imagination of our nation for almost half a century. Aquarius may be the only underwater laboratory operating in our oceans today, but based on its record of productivity and accomplishment, and the human spirit of exploration, it won't be the last.

For More Information on the Aquarius Underwater Laboratory, please visit the Aquarius Web site .

References

Barth, B. 2000. Sea Dwellers: The humor, drama and tragedy of the U.S. Navy SeaLab programs. Doyle Publishing Company, Inc. Houston, TX. 184 pages.

Bond, G.F and H.A. Siteri (Editor). 1993. Papa Topside: The Sealab Chronicles of Capt. George F. Bond, US Navy. United States Naval Institute. Book News Incorporated. Portland, OR 270 pages.

Heidelberg, K.B. 1999. The effects of water flow and zooplankton prey behavior on scleractinian coral and heterotrophy. University of Maryland (USA). 207 pp.

Koblick, I.G. and J.W. Miller. 1995. Living and Working in the Sea. Flagstaff, AZ. Best Publishing Company. 438 pages.

Leichter, J.J. and S.L. Miller. 1999. Predicting high frequency upwelling: Spatial and temporal patterns of temperature anomalies on a Florida coral reef. Cont. Shelf Res. 19:911-928.

Paul, J.H., J.B. Rose, J.Brown, E.A. Shinn, S. Miller, and S.R. Farrah. 1995. Viral tracer studies indicate contamination of marine waters by sewage disposal practices in Key Largo, Florida. Appl. Env. Microbiol. 61(6): 2230-2234.

Sebens, K.P., S. Grace, B. Helmuth, E. Maney, and J. Miles. 1998. Water flow and prey capture by three scleractinian corals, Madracis mirabilis, Montastrea cavernosa, and Porites porites in a field enclosure. Mar. Biol. 131(2): 347-360.

Citation Credit: Marine Technology Society Journal. Volume 34 (4): Pages 69-74.

The Web team gratefully aknowledges this contribution by Dr. Steven L. Miller and Craig Cooper of the UNCW Center for Marine Science National Undersea Research Center

 

 

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