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GCN : December 2012
GCN DECEMBER 2012 • GCN.COM 23 below freezing most of the time. Anyone who goes into the water won't survive long. Into this netherworld NOAA has sent various data-taking probes over the years. Satellites have been used, but with limited success because they can't look below the surface of the water. And in the Arctic, where clouds cover the sky more than 90 percent of the time, satel- lites must simply wait for a clear day to gather any data. Buoys have been used in cold areas, but they are stationary plat- forms and not robust enough to survive the ice floes of the Arctic waters. Giant ice-breaking ships can tow sensor ar- rays, but they require full crews and cost the government between $25,000 and $80,000 per day. Nevertheless such efforts have been made and costs have been borne in part because the Arctic Ocean has become invaluable when looking for answers about climate change. The ice that cov- ers the ocean is forming later every year, and melting sooner. The resulting darker ocean water absorbs the sun's radiation instead of reflecting it as sea ice does. That creates a cycle of less ice, more heat, and a warming of the upper ocean during the summer months that could have serious repercussions for the entire planet. Recording temperatures, especially in columns of water going down six meters below the surface, could help scientists predict future key climate changes. Data could be shared with NOAA's Fisheries Service, for example, to create smarter seafood management plans. NOAA's Meinig thought robots might handle data collection tasks more capa- bly than any of device --- and for a lot less money. As it turns out, NOAA is no stranger to using swimming robots to record data. The agency has bought sev- eral from Liquid Robotics Inc., of Sunny- vale Calif., to monitor the world's other oceans. In fact, a set of the company's Wave Glider robots are currently swim- ming off the coasts of California and Hawaii. Depending on configuration, a Wave Glider can cost between $175,000 and $250,000, but offer near continuous operation once deployed. Graham Hine, Liquid Robotics senior vice president for product management, explained why the robots his company manufactures are perfect for unmanned exploration of the world's oceans. "The Wave Gliders are propelled by wave power, so they can operate for months at a time, never need to stop for refuel- ing, and are robust enough to survive in tough conditions," he said. In fact, two Wave Gliders recently survived almost direct hits from Hurri- cane Isaac. Hine said the only way the operators knew that one craft had been in the hurricane was the fact that it sent back 550 readings per minute instead of its programmed 600. The lost 50 read- ings each minute probably happened because the bot was completely under- water at the time and not able to trans- mit a signal. But it survived the storm without a scratch. ROBOTS VS. PINGOS In fact, for day-to-day operations Wave Gliders have proven to be surprisingly ro- bust in the field. Liquid Robotics has been testing them in a project during which several Wave Gliders swam 9,000 miles across the Pacific Ocean. "We only had one problem on that trip," Hine said. "A shark bit the naviga- tion cable on one of them, which sent the unit into a slow spin. Thankfully, that happened about 150 miles offshore of Hawaii, so we were able to retrieve it." Wave Glider are not normally affected by heat either because the dry boxes con- taining the payload and control functions sit partially below the waterline so excess heat is dissipated by thermal transfer. For the Arctic mission, however, ex- treme cold was the potential enemy. Nobody at Liquid Robotics knew if a Wave Glider could survive such dramatic temperatures. "We have a cabin up in Lake Tahoe, so we took one up there in winter and let it get snowed on," Hine said. "We wanted to see if snow would block the solar panels. But after a month in the water, it didn't hurt it at all. We also did several tests to Officials from NOAA and Liquid Robotics launch a test of one of the company's self- propelled Wave Gliders, which can explore and transmit data from the frigid waters of the Arctic Ocean. LIQUID ROBOTICS INC.