Two seven-meter-long sailboats are returning to California this spring, after spending nearly eight months traversing the Pacific Ocean. These aren’t ordinary sailboats with human crews, but driverless semiautonomous drones equipped with sensors for probing the ocean. The drones were developed by a California-based marine tech startup called Saildrone, who closely collaborated with the National Oceanic and Atmospheric Administration (NOAA). The nautical drones are returning from their longest test out in the Pacific Ocean, which is a big step for justifying their capability of replacing an aging and costly network of buoys that are currently a researcher’s primary means of monitoring for signs of climate disruptions prompted by El Niño events. In addition to temperature, wind, and solar radiation data, the Saildrones measured how the ocean and air exchange gases like oxygen and carbon dioxide. The drones used Doppler instruments to monitor currents coursing up to 100 meters below the surface, while their sensors could reveal patterns that could help explain how the tropical Pacific emits, rather than release carbon dioxide, like most of the ocean.
Before the current methods involving buoys and satellites, most sea surface data was gathered from ships. NOAA scientists are now looking into sending drones because many think these can facilitate the next game-changing advancement in oceanography. Over the next decade, hundreds to thousands of these solar- and wind-powered nautical drones could traverse the world’s oceans, relaying data collected on air and sea surface conditions to satellites. The timing couldn’t be better for scientists studying the El Niño-Southern Oscillation—a set of shifting global temperature and rainfall patterns caused by warm surface waters sloshing back and forth across the equatorial Pacific every couple of years. NOAA has relied on an array of buoys anchored to the Pacific Ocean floor since the 1980s, in a network called the Tropical Atmosphere Ocean (TAO) Array, which assists researchers in studying and forecasting these radical weather shifts. TAO proved to be a resourceful tool for scientists, which led to similar buoy networks installed in the Indian and Atlantic Oceans.
In the last decade however, the TAO Array manifested a nasty side-effect. The buoys naturally became clustered with sea vegetation, making them attractive to fish, which in turn attracted fishermen—both recreational and commercial. As a result, TAO buoys started appearing on maps of global fish catches. The buoys were damaged as fishermen physically interacted with them while trying to reach or extract their catches. This resulted in a spike of maintenance costs, while the deployment of new buoys were limited by budget cuts and rising expenses of operating research ships.
Engineer and Saildrone founder Richard Jenkins saw an opportunity arise from these circumstances, and constructed a wheeled sailboat he named Greenbird. In 2009, the craft broke the land-speed record for wind-powered vehicles when it hit 202 kilometers per hour on a dry Nevada lake bed. Afterwards, Jenkins helped two philanthropists with researching and designing a vessel on a $60 million budget, a cost that made him ponder whether a smaller seafaring version of his Greenbird could collect data cheaper and more efficiently. An ocean-going Saildrone would ideally require no fuel for propulsion, since instruments and communications could be powered by solar panels, while the drone could use the wind to set and follow simple set waypoints.
Jenkins eventually received $2.5 million from the same two philanthropists he helped, to get started on a test craft, which he completed by 2013. The nautical craft’s maiden test voyage between California and Hawaii was a success, during which the drone was propelled by a carbon fiber composite sail about five meters tall. In 2015, the drone endured 40-knot winds during a three-month expedition into the Arctic to study native marine life. The early success led researchers to ponder whether drones could help anchor observations in the Pacific Ocean. Ideally, drones could sail in giant circles around virtual mooring points, or other preplanned patterns before returning to port for an annual cleaning. Circling back to the $60 million budget Jenkins worked on, nautical crafts like his Saildrones could be cheaper. Saildrone, for example, charges $2500 a day to collect data, while ship time can exceed $30,000 a day.
Their first test in Pacific Ocean waters occurred on September 5, 2017, when the two Saildrones departed from San Francisco, California, for equatorial waters. Cold tongues of surface water extending westward from the South American coast were spotted by satellites, an indicator of a strong La Niña (El Niño’s opposite number). Upon reaching the Equator, the drones got stuck in the doldrums—a wind dead zone, where they eventually caught onto a breeze and escaped. While looking back at data collected from the cold tongues, researchers were surprised to find one-degree shifts in water temperature in less than a kilometer. This caught scientists completely off-guard, since this is the type of detail a satellite’s lower resolution would smear out, while a stationary buoy would have missed. Researchers point how these sharp gradients aren’t reflected on current climate models, which could affect the above atmosphere. Arrays like TAO will continue to be important, but the introduction of cheaper more resilient accessories could help gather data that hasn’t been accounted for since the project’s inception.
Filed Under: M2M (machine to machine)