scientists have told Xinhua. The deep-sea electric ROV system named Haiqin, which was designed and built by Shanghai Jiao Tong University, reached a depth of 4,140 meters during the sea trial early on Saturday morning. Equipped with high-definition cameras, robotic arms, sonar systems and sensors -- the ROV demonstrated capabilities including automatic heading control and precise hovering. The 3.6-tonne ROV successfully collected deep-sea biological samples and sediments -- with these findings taken to a supporting research vessel named Zhong Shan Da Xue. In a significant development, this voyage also saw the simultaneous deployment of the full-ocean-depth autonomous and remotely-operated vehicle (ARV) named Haidou-1, marking the first time two distinct deep-sea unmanned submersibles had conducted coordinated scientific operations via a single supporting Chinese research vessel. (Xinhua)