Xuelong 2 Enters Southern Ocean on Antarctic Mission

More than two weeks into its voyage to Antarctica for the 42nd national Antarctic expedition, China's polar research icebreaker Xuelong 2 approached the Southern Hemisphere's "Roaring Forties" on November 16.

Antarctica, with an area of 14 million square kilometers, is covered by an ice sheet 2,450 meters thick on average. The continent remains one of the most remote and data-scarce regions on Earth. The ongoing scientific work there contributes directly to understanding global climate patterns, sea-level change and sustainable ocean resource management.

Delivered in 2019, Xuelong 2 is China's first domestically built polar research icebreaker and the world's first capable of breaking ice both bow-first and stern-first. It operates alongside the vessel Xuelong, supporting scientific research, environmental monitoring and logistics for Chinese stations in polar regions.

Before Xuelong 2 entered service, Xuelong was the nation's only comprehensive polar research vessel for nearly 30 years. While it completed numerous Arctic and Antarctic missions, its icebreaking capacity limited operations to peak summer months and prevented access to heavily iced areas such as the central Arctic Ocean.

Xuelong 2 was developed to address these constraints. At 122.5 meters long with a design displacement of nearly 14,000 tons, it is equipped with two 7.5-megawatt azimuth thrusters. It can break 1.5 meters of ice plus 0.2 meters of snow continuously at speeds of two to three knots in either direction.

Antarctic Sea ice is generally divided into first-year ice and multiyear ice, which has survived at least one summer melt. Multiyear ice is mainly found in the western Weddell Sea, Bellingshausen Sea and Amundsen Sea. The other areas are dominated by the thinner first-year ice.

According to Yang Kai, an official working at Xuelong 2, its capabilities allow it to navigate through most Antarctic Sea ice, significantly expanding operational reach. In heavy ice ridges, where conventional bow-only icebreakers often get stuck while turning, the stern-first mode proves critical. The ship's azimuth thrusters rotate 360 degrees, enabling the propellers to cut through thick ridges from behind.

"We use the stern to break up the toughest sections first, then switch to bow mode," Yang said. "Bidirectional icebreaking saves time and allows us to penetrate thicker ice."

This capability was demonstrated during China's 40th Antarctic expedition.

In the Ross Sea, Xuelong 2 escorted the supply vessel through more than 1,000 nautical miles of ice-covered waters. Facing ice ridges over four meters thick and narrow channels, the icebreaker used satellite data, aerial reconnaissance, bow-and-stern icebreaking and wake-assisted clearing to open a channel over 30 meters wide. This enabled the supply vessel to reach the site of China's new Qinling Station ahead of schedule and deliver essential construction supplies.

Xuelong 2 has also extended the window for Antarctic operations. While most countries conduct fieldwork between November and March, Xuelong 2's enhanced icebreaking and cold-weather performance allows earlier arrivals and later departures. During the 41st expedition, it set a national record with a 208-day voyage covering more than 40,000 nautical miles, the longest single-ship polar mission in China's history.

Beyond logistics, Xuelong 2 functions as a mobile platform for sci-tech research. It is equipped with a moon pool，a 3-by-3-meter vertical opening through the hull that enables instrument deployment even under full sea ice cover or in severe weather.

To prevent ice accumulation, the moon pool has a watertight bottom hatch, drainage pumps and heating systems. "It's like digging a hole through the ship," said chief engineer Li Wenming. "This ensures sampling can continue safely in extreme conditions."

The vessel also carries a 240-channel seismic system for sub-seafloor imaging, multibeam sonars for seafloor mapping, a sub-bottom profiler, an echo-integration system for marine biomass estimation and a full-ocean-depth echosounder capable of measuring depths beyond 10,000 meters.

A dual dynamic positioning system helps the ship stay in position in challenging conditions. By coordinating thrusters, rudders, and side propulsion units, it counteracts wind and current forces. The system supports precise deployment of large equipment in Sea State 4 and drifting surveys in winds up to Force 6 with 1.5-knot currents.

As Xuelong 2 continues its journey toward Antarctica, it underscores China's commitment to advancing polar science through peaceful, cooperative and evidence-based exploration, contributing to global knowledge of one of Earth's last frontiers.

Source: Science and Technology Daily