14 Platform one October/November 2024 | Uncrewed Systems Technology NASA is developing an undersea robot that can operate in a swarm under sea ice in Antarctica, writes Nick Flaherty. The IceNode project envisions a fleet of autonomous robots helping to determine the melt rate of ice shelves. The underwater prototype robot has been tested in the frozen Beaufort Sea, north of Alaska, by engineers from NASA’s Jet Propulsion Laboratory. Engineers operated the cylindrical robot in Arctic temperatures of -45 C. It descended 100 m (330 ft) into the ocean, where its instruments gathered salinity, temperature and flow data. It was connected by a tether to a tripod that lowered it through a borehole, and the team conducted tests to determine the adjustments needed to take the robot off-tether in future. The undersea vehicles measure 2.4 m long by 25 cm in diameter with a threelegged ‘landing gear’ that springs out from one end to attach the robot to the underside of the ice. The robots do not feature any form of propulsion; instead, they position themselves autonomously with the help of software that uses information from models of ocean currents. Released from a borehole or vessel in the open ocean, the robots ride the currents on their journey beneath an ice shelf. Upon reaching the target area, the robots drop their ballast and rise to affix themselves to the bottom of the ice. Sensors measure how fast the warm, salty water is circulating up to melt the ice, and how quickly colder, fresher meltwater sinks. The IceNode fleet will operate for up to one year, continuously capturing data, including seasonal fluctuations. Then they will detach themselves from the ice, drift back to the open ocean and transmit their data via satellite. This data will help to improve computer models that predict sealevel rise and give more accurate melt rates, particularly beneath ice shelves, which can be miles long. While they do not add to sea level rise directly, ice shelves crucially slow the flow of ice sheets towards the ocean. Places where scientists want to measure melting ice are among Earth’s most inaccessible, and in particular an underwater area known as the grounding zone, where floating ice shelves, ocean and land meet. This zone is dangerous for humans and satellites can’t see into the cavities. “We’ve been pondering how to surmount these technological and logistical challenges for years, and we think we’ve found a way,” said Ian Fenty, a JPL climate scientist and IceNode’s science lead. “The goal is getting data directly at the ice-ocean melting interface beneath the ice shelf.” “These robots are a platform to bring science instruments to the hardest-toreach locations on Earth,” said Paul Glick, a JPL robotics engineer and IceNode’s principal investigator. “It is meant to be a safe, comparatively low-cost solution to a difficult problem.” Undersea robots Working swarms under sea ice Undersea monitoring of an ice shelf (Image courtesy of NASA)
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