Phoning Home from the Seafloor: New Undersea Laboratory Will Provide First Real-time, Long-Term Ocean Measurements
Pitting science and technology against the storm-driven forces of the open coastal ocean, a team of engineers from the Woods Hole Oceanographic Institution in Massachusetts and scientists from Rutgers, the State University of New Jersey, has established what may be the first long-term undersea observatory in the world.
The new undersea research station directly links the coastal ocean with the laboratory and the Internet for world-wide access to environmental information which can be collected continuously for decades or more.
LEO-15, for Long-term Ecosystem Observatory in 15 meters of water, became a reality in September 1996 when the observatory's two scientific outposts, or nodes, were installed on the seafloor off the coast of New Jersey, 15 meters (about 50 feet) below the surface of the Atlantic Ocean. The system was designed, built and installed by the Oceanographic Systems Laboratory (OSL) in the Department of Applied Ocean Physics and Engineering at Woods Hole Oceanographic Institution (WHOI). Senior Engineer Christopher von Alt, who heads the OSL team, and Biologist J. Frederick Grassle of Rutgers served as co-principal investigators on the project.
The new undersea observatory is the result of a ten-year collaboration between Grassle, who was a Senior Scientist in WHOI's Biology Department at the time, and von Alt. During a 1986 conversation at WHOI, the two men began discussing new ways of getting information out of the ocean. A major limitation was the inability of scientists and engineers to make frequent observations of ocean processes from one place in the ocean over long periods of time. Grassle, who remains affiliated with WHOI as an Adjunct Scientist in the Biology Department, and von Alt envisioned a network of underwater observatories from which robots could be deployed and remotely directed by computers anywhere in the world. These visions became a joint research program funded by the National Science Foundation in 1992. Additional support has come from the National Oceanic and Atmospheric Administration.
LEO-15 's two scientific outposts or nodes, one closer to shore than the other, consist of an outer shell and an internal instrument frame to which all the experiments, sensors and vehicles are or will be connected in some way. Guest connections will enable many experiments to take place at once, or to easily add or subtract experiments as research programs change. The outer shell, designed to be resistant to fishing trawls, is ten feet long by ten feet wide by five feet in height and is made of stainless steel painted to prevent it from becoming fouled, or covered by biological growth. Each shell is secured in place on the seafloor by four anchors designed to withstand heavy currents and seas which develop in the open ocean, particularly during storms. The nodes and their internal instrument frames have a twenty-year life span and can be serviced by divers for maintenance, upgrades and repairs as needed.
The two undersea stations are linked to LEO-15 project's field station, an old U.S. Coast Guard life-saving station at Tuckerton, New Jersey, with nine kilometers (about 5 miles) of electro-optic cable which contains optical fibers to transfer information and copper wires to conduct the electricity. The cable, buried in the seafloor to protect it from commercial clam dredges and recreational boat anchors, provides a real-time, two-way communication and video link between the undersea world to the shore station and from there via computer to the Internet. WHOI engineers have been testing the system since installation in September, and while it is not yet fully operational, the vertical profiler and other sensors in each node are already providing valuable data about the currents and water conditions.
"Scientists, engineers, and educators can access the coastal ocean, monitoring experiments and adjusting the direction of an experiment if needed based on the data they are receiving from LEO-15, from essentially any classroom, office building, or laboratory in the world," notes von Alt. "Up to now divers had to go out, weather permitting, and conduct experiments or collect data. It couldn't be done every day. Now we have a system that can do it every day, regardless of weather. One of the major advantages of LEO-15 is the continuous and ample electrical power the cable from shore provides for a variety of experiments and instruments. Power consumption severely limits most instruments used in the ocean, which often have to rely on batteries. "
Instruments inside the two LEO-15 nodes, directly controlled by researchers over the Internet, support sensors which monitor water quality parameters, such as temperature, salinity, oxygen content, the height of waves, and range of the tides. They also monitor water currents, nutrient levels, sand migration, and water clarity. Some instruments, like the vertical profiler, are tethered to the seafloor outposts , They rise vertically through the ocean to measure how its properties change with depth on preprogrammed intervals, returning to the node when the measurements have been completed. Repeating these profiles over time provides a three-dimensional representation of the ocean as it moves past the observatory. Such measurements will aid calibration of ocean color satellites monitoring surface conditions that can affect fisheries. Other instruments fixed to the seafloor have video cameras and advanced imaging systems and sensors to monitor and study various forms of life and their interaction with the environment. Ocean frontal systems, much like atmospheric highs and lows, can be tracked and experiments altered to better study ocean conditions during episodic events like hurricanes.
"These instruments offer scientists a means of returning to the same location over and over again to see what is happening," Woods Hole's Chris von Alt says. "The coastal ocean is one of this nation's most important natural resources. Issues associated with its management, from fisheries to pollution, are the subject of constant debate by the public, the media, and by politicians. A common aspect of these debates is the need for better information about the ocean environment on which to make wise decisions. Until now we have depended on ships, satellites, and a few buoys for information that basically gives us only a snapshot. What we really need is a fish eye's view of what is happening in the ocean, and LEO-15 will give us that perspective."
The WHOI engineering team is now developing a future component of the system, an autonomous or untethered torpedo-like vehicle singly and collectively called REMUS (Remote Environmental Measuring UnitS). A prototype has been built and successfully tested in the ocean at Woods Hole and in nearby ponds. In the near future, REMUS will swim out from its docking station in the nodes on pre-programmed courses to explore phenomena detected by satellites in space or by other instruments on the seafloor. Sometimes working in groups and at other times working alone, these free-swimming vehicles will be able to explore the coastal ocean for hours at a time, making scientific measurements, taking pictures, and then returning to the underwater research station with the information they have collected. Once in their docking station, the information they have collected will be transferred back to land and out over the Internet to scientists, engineers or students who have directed each REMUS survey.
"LEO-15 has tremendous capabilities that seemed impossible just a few years ago," WHOI's von Alt says. "Operating a global system of commercial undersea farms from a central office over the information super highway is a concept that Captain Nemo might have conjured up for us today if Jules Vern had envisioned the Internet and the tremendous impact that it and other new technologies are now having on our ability to understand and work under the sea. Such an idea might have seemed far-fetched a few years ago, but now it is a possibility well within our horizon."
For additional information, contact: Shelley Lauzon, Senior News Officer Woods Hole Oceanographic Institution, Woods Hole, MA, 0254 508-289-2270 FAX: 508-457-2180 firstname.lastname@example.org