Sea trial and free-fall hydrodynamic research of a 7000-meter lander

Hadal science is one of research frontiers in earth science. Exploring the hadal zone has become an attractive and challenging event in marine engineering due to extremely hostile environment. Only few underwater vehicles have the ability to dive deeper than 6000 meters. Free-fall vehicle, also known as “lander” has been widely applied in marine investigation for decades, and has made a spectacular achievement in hadal research. This paper presents the sea trial and corresponding results of a 7000-meter lander, which mainly focused on biology and ecology research in hadal zone. The sea trial was conducted in shallow water area and deep-sea area in South China Sea, where functional tests, descent/ascent speed characteristics, and comprehensive performance were studied. During the deep-sea trial, a serial of scientific research achievements was obtained. Sea trial results validated the multi-function, effectiveness and stability of the lander system.