Autonomous Underwater Vehicle Attempts to Make the First Trans-Atlantic Crossing
The remote-controlled submarine, designed to 'fly' underwater, promises to greatly expand data gathering. (Rutgers University/Associated Press)
Improved with slick, anti-fouling paints and more powerful batteries, a new undersea probe was launched this past Monday by Rutgers University scientists in a second attempt to make the first trans-Atlantic crossing by an autonomous underwater vehicle.
The canary-yellow robot RU-27 went into the water off the New Jersey coast this past Monday. Once in launched mission controllers, preparing to map out a course to insert the undersea glider into the fast-moving Gulf Stream current far offshore.
In eight months, the Rutgers team is hoping their probe, dubbed the Scarlet Knight after the university mascot, will be in Spanish waters and ready for pickup before the onset of winter storms. The machine will dive and glide forward in eight-hour sessions, gathering oceanographic data and surfacing three times a day to beam it back to the Mission Control center via a satellite link.
“We’ll get one hour of ocean data each day for the next eight months as it makes its way across,” said Josh Kohut, an assistant professor at the university’s Institute of Marine and Coastal Sciences. In dives beyond 600 feet, RU-27 will collect temperature and salinity levels and measure the speed and direction of ocean currents — the undersea equivalent of measuring temperature and wind in the atmosphere, Kohut said. And like weather observations, the glider data will play a role in plotting the course of climate change, he added: “They are the measurements that go into the global climate models.”
An earlier vehicle, RU-17, was lost in late October 2008 about 220 miles short of the Azores, a mid-Atlantic island group where the Rutgers team asked local oceanographers to help with a rescue effort after the probe reported an onboard leak. They now think the glider sank after colliding with an animal or submerged object, said Scott Glenn, an oceanography professor, who sums up the dangers as “storms and biology.” Improvements to RU-27 include a rubbery Teflon coating on the hull and new anti-fouling paint to keep hydroids and other growth from attaching to the slow-moving craft, Glenn said. Builders beefed up its battery power too, adding more lithium cells to provide at least 300 days of power, up from 230 days in the previous model.
“We take about the same energy as six Christmas tree light bulbs,” Glenn said. The new energy budget makes it more feasible for the craft to lay-to during bad weather, if pickup is delayed this fall, he said. To save power in survival mode, controllers could turn off pumps, reduce the times that the probe phones home by satellite, or shut down sensors, he said. On this mission, the first gauntlet is the edge of the continental shelf 70 to 80 miles offshore. “A lot of fishing goes on at the shelf because it’s so rich in nutrients, so we dive deep to avoid the nets and gear.”
The glider gets its forward motion by submerging, and riding on stubby wings, then surfacing and repeating the process. Unmanned and without a motor, the glider can rise and dive, seeking out currents that will carry it along without worrying about re-fuelling.
Gliders move through the ocean by using battery-powered motors and mechanical pumps to move ballast water or oil from inside the vehicle to a bladder on the vehicle’s exterior. This changes its volume and buoyancy without changing its mass, causing it to sink or rise while at the same time pushing it forward. Whenever the glider comes to the surface, it sends a radio signal back to the scientists.
“The launching is tremendously exciting because there is just so much that we don’t really know about what happens in the oceans,” said Jane Lubchenco, head of the National Oceanic and Atmospheric Administration. “The ocean plays such a critical role in the dynamics of the climate system, having a better understanding of what’s happening in real time is invaluable information,” said Lubchenco. “We’re beginning to be able to infer much about the kinds of plants and animals and microbes that may be present from some of the kinds of data that the glider will be taking,” she added.
The glider is part of the Integrated Ocean Observing System, a project to collect and use ocean information continuously covering oceans, coastal waters and Great Lakes.
“Oceans are vital to all of life on earth. A billion people a day depend on seafood for their primary or sole source of protein, oceans drive the climate system, oceans provide most of the oxygen that we breathe,” Lubchenco said. “They provide wonderful places for recreation, they are an important source of jobs, livelihoods. Just within the U.S., half of Americans live in coastal areas and 60 per cent of gross domestic product comes from coastal areas, so clearly they are an integral part of our very fabric. Yet we know precious little about them,” she said.
“We’re constructing a vast, three-dimensional jigsaw puzzle,” Lubchenco said. “We have bits and pieces of the puzzle and we’re building out from that. So every track that this glider makes, every new sensor that we have in the oceans” provides data to construct a more meaningful and dynamic picture of the world, she said.
“We have only just begun to tap the potential that is here on planet ocean.”
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