Chinese scientists and engineers have pushed far beyond a string of US military bases known as the second island chain, reaching a seamount in the western Pacific Ocean 2,000 metres (6,561 feet) below the surface to test a smart mining vehicle designed to harvest cobalt-rich deposits, gathering critical performance data. The robotic miner showed its ability to traverse rugged seabeds littered with cobalt crusts, autonomously adjusting its posture to avoid overturning or being...