China Launches Vessel to Drill 11km into Earth’s Mantle

China's recently commissioned deep-ocean drilling vessel, Meng Xiang, has begun operations in previously unexplored regions, drilling to depths of up to 11,000 meters (36,000 feet) beneath the seafloor. Its mission is to penetrate the Earth's crust and reach the Mohorovičić discontinuity—the boundary between the crust and the mantle. This advancement in drilling technology is expected to facilitate the recovery of mantle samples, potentially yielding new insights into the structure and evolution of the Earth.

Built at a cost of approximately $470 million, the Meng Xiang possesses specifications that position it at the forefront of global scientific drilling capabilities. With a gross tonnage of 33,000 tonnes and a beam of 32.8 meters, it can operate autonomously for 120 days and has a range of 15,000 nautical miles, enabling sustained operations in remote ocean regions.

China's first 11,000-meter (11km) deep-ocean drilling research vessel launches.

Unprecedented Drilling Depth and Scientific Goals

The most notable feature of the Meng Xiang is its 11,000-meter drilling depth capacity. This surpasses the operational limits of its predecessors, including the retired US vessel JOIDES Resolution (8,385 meters) and Japan's Chikyu (10,000 meters). This capability enables the vessel to pursue ambitious scientific objectives, including the long-sought goal of penetrating Earth's crust to sample the upper mantle.

A primary mission target is the Mohorovičić discontinuity (Moho), the boundary separating the crust from the denser mantle below. First identified by Croatian seismologist Andrija Mohorovičić through changes in seismic wave velocities, the Moho represents a fundamental transition zone. Direct sampling below the Moho, potentially reaching mantle peridotites, is expected to provide crucial data on the composition, formation, and evolution of Earth's crust and contribute significantly to validating and refining plate tectonic theory. Historical attempts, like the original "Project Mohole" in 1961 and the more recent SloMo Project, were unable to reach this target.

Achieving this depth presents considerable technical challenges, particularly in managing borehole stability under high pressure in deep water (potentially 4,000 meters) overlying significant rock thickness (up to 6,000 meters). Engineers are developing advanced drilling systems, including a specialized drilling mud circulation system projected for readiness around 2030, alongside titanium alloy drill components designed for high-temperature, high-pressure environments.

Technical Specifications of the Meng Xiang

The Meng Xiang represents a significant engineering achievement designed specifically for ultra-deepwater scientific drilling. Key specifications underscore its advanced capabilities:

Vessel Characteristics: The ship measures 179.8 meters in length, has a beam of 32.8 meters, and possesses a gross tonnage of 33,000 tonnes. It is built for sustained operations, capable of working continuously for up to 120 days and covering a range of 15,000 nautical miles without resupply, making it suitable for extended missions in diverse marine environments, including polar regions.

Drilling System: Central to its function is a drilling system engineered to operate in extreme conditions. It utilizes components such as a titanium alloy drill rod and specialized diamond bits, specifically designed to handle the high-temperature and high-pressure environments found at target depths reaching up to 11,000 meters.

Onboard Laboratories: Supporting the drilling operations is an extensive and versatile suite of onboard research facilities. The vessel houses nine specialized laboratories spanning over 3,000 square meters, dedicated to disciplines including marine science, microbiology, and paleomagnetism. These advanced labs incorporate technologies like digital twin systems, enabling real-time monitoring of drilling parameters and facilitating integrated, immediate scientific analysis of core samples and data at sea.

Scientific Goals and Research Potential

The Meng Xiang's operations will be guided by China's Deep Ocean Drilling Program, an initiative designed to manage numerous expeditions between 2025 and 2035. A cornerstone of this program is fostering international collaboration; researchers worldwide will be invited to propose projects and participate in expeditions. Aligning with the established practices of programs like the International Ocean Discovery Program (IODP), data and core samples acquired during missions are intended for open access within the global scientific community.

Initial scientific drilling campaigns are scheduled to begin in 2025. While the long-term ambition includes attempting to drill through the Earth's crust to the mantle (targeting the Moho discontinuity by 2030, potentially in thin-crust regions of the Pacific or Indian Oceans), the Meng Xiang's capabilities support a comprehensive research agenda.

The vessel's capabilities will enable diverse research objectives across key Earth science domains:

• Geological Studies: Investigating tectonic history and crustal structure, potentially including searches for evidence of ancient, subducted ocean basins near Taiwan and detailed studies of the oceanic crust architecture.
• Climate Research: Reconstructing past environmental conditions by analyzing sediment cores, such as those proposed for drilling on the Sunda Shelf to understand long-term sea-level changes.
• Biological Exploration: Probing the limits and nature of microbial life within deep subsurface environments, including unique settings like the Mariana Trench.
• Ocean Dynamics: Examining the history and impact of major ocean currents. A notable proposed project involves drilling in the challenging waters between Australia and Antarctica to understand the origin and evolution of the Antarctic Circumpolar Current, leveraging the Meng Xiang's stability and endurance to study this critical component of the global climate system.

The Meng Xiang and its Deep Ocean Drilling Program are designed to advance scientific ocean exploration by addressing a diverse range of significant questions identified by the international ocean drilling community, thereby continuing the legacy of prior global efforts in this field.

Commencement of Operations and Future Outlook

The Meng Xiang has formally entered service, with initial scientific drilling missions anticipated to begin by the end of 2024 or early 2025. The ambitious Moho drilling expeditions are targeted for implementation before 2030, likely focusing on regions in the Pacific or Indian Oceans where the oceanic crust is relatively thin.

The Meng Xiang represents a major advancement in deep-ocean drilling technology and scientific exploration. Its ability to drill to 11,000 meters, combined with its advanced laboratories and commitment to international cooperation, makes it a vital asset for addressing fundamental questions about Earth’s structure, history, and ecosystems. As it prepares for its first expeditions, the Meng Xiang stands to contribute valuable knowledge to the global scientific community, with implications for geology, climate science, and beyond.

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Note: This information draws from a recent study in journal Nature Geoscience exploring the possibility of reaching the Moho via ocean drilling with the Meng Xiang.