The Moho is in reach of ocean drilling with the Meng Xiang

Abstract

The Meng Xiang (‘Dream’ in Chinese) is a recently commissioned vessel that was specifically designed to drill through intact ocean crust into the mantle¹⁰. Able to operate in rough seas with a dynamic stabilization system (pictured), it can drill down up to 11 kilometres using a variety of modes — including both riser and riserless systems — optimized for settings from the tropics to the poles. The titanium alloy drill rod and the diamond bit enable reliable drilling in the high-temperature and high-pressure environment. Rapid processing and analysis of core material will take place in a floating laboratory that can operate continuously for months. But we must be patient, allowing enough time for the process of trial and error. For any chosen site, we must be prepared for multiple entries, multiple expeditions, and perhaps multiple years to reach the Moho. Beyond targeting the Moho, the ship has the capability to carry on the legacy of the JOIDES Resolution — a drilling vessel that was operated by the International Ocean Discovery Program until 2024 — by addressing the full range of scientific questions identified by the international ocean drilling community⁸.

The first scientific drilling expeditions by the Meng Xiang are expected to begin next year and plans are being developed to carry out full-scale drilling to the Moho beneath the Pacific or Indian seafloor before 2030. The oceanic crust is thin in each region, though sites can be chosen to focus on differences in crust formed from both fast- and slow-spreading ridges. The drill core samples will give scientists an unprecedented opportunity for understanding the architecture and formation of the ocean crust as well as the petrological nature of the oceanic Moho — which will help ground truth many important aspects of plate tectonics theory. Alongside this, the samples will also be used to explore the bottom limit of Earth life among other research interests. With this long-sought goal to sample the boundary between crust and mantle within reach with the Meng Xiang, we advocate for the development of an international collaboration⁶ around this shared goal in the spirit of ‘mission Moho’. International scientists will be welcome to join the drilling expeditions and to share the samples for their research following a moratorium similar to the Integrated Ocean Drilling Program (IODP).