Scientific investigation application of hadal landers in the Mariana Trench

Hadal science has become one of the research frontiers in earth sciences in recent years. Free-fall vehicle, also known as “lander” has provided new opportunities to investigate the hadal zone. Two hadal expeditions in the Mariana Trench were conducted successively with the support of Chinese Academy of Sciences since last June to this March. Two 7000-meter rating landers named Tian Ya and Hai Jiao were applied in the first expedition. Tian Ya was technologically promoted to adapt the static pressure of 11000-meter depth within 5 months, while another hadal lander named Wan Quan was built simultaneously, and were applied in the second expedition. Totally 29 deployments were accomplished, and arrived at the bottom of the Challenge Deep for 11 times. Results showed the proposed landers and related deep-sea technology in superior performance. Significant achievements were obtained in the two expeditions. It is believed that 10911m is the maximum depth of the Mariana Trench due to in-situ measurement by pressure sensor. The liparid was observed in 8152m, which was the deepest habitat ever found. Scientific data and samples obtained in the two expeditions are now under research by scientists, and it would help to understand the hadal zone better.