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China has achieved a significant milestone in space science with the recent completion and national acceptance of the Chinese Meridian Project (CMP) Phase II on March 21. This project represents the world’s first comprehensive ground-based monitoring network spanning the entire Sun-Earth space environment, extending from the solar atmosphere to near-Earth space.

With construction starting in 2019, CMP Phase II established a “two vertical, two horizontal” double-cross monitoring network along the 100°E and 120°E longitudes and the 30°N and 40°N latitudes. By integrating 16 new observation stations with the original 15 CMP Phase I stations, the project enables unprecedented three-dimensional monitoring of space weather phenomena, from solar eruptions to Earth’s atmospheric responses.

CMP Phase II features several key technological advancements:

First, the Daocheng Radio Telescope (DART), a ring-shaped array, captures 3D coronal tomography with a 10-solar-radius field of view, enabling exceptional tracking of solar activity.

Daocheng Radio Telescope (DART)

Second, a groundbreaking metastable helium lidar array allows for continuous height-resolved detection of atmospheric metastable helium within a height range of 200 to 1000 kilometers.

Array Large Aperture Lidar (ALA-Lidar)

Third, the project includes the world's first tristatic incoherent scatter radar system, which employs phased array technology to perform ionospheric computed tomography (CT) scanning and 3D imaging over distances of thousands of kilometers.

Sanya Incoherent Scatter Radar Tristatic System (SYISR-TS)

Fourth, the Chinese Dual Auroral Radar Network (CN-DARN), a mid-latitude high-frequency radar array achieves 24/7 observation of ionospheric dynamics across the Asia, covering over 4,000 km meridionally and 10,000 km zonally.

Chinese Dual Auroral Radar Network (CN-DARN)

Finally, the project features China's first facility dedicated to reconstructing three-dimensional solar wind structures, enhancing predictions of the interplanetary environment.

Interplanetary Scintillation Telescope (IPS Telescope)

Since its trial phase, CMP Phase II has demonstrated high reliability. Notably, it captured the May 2024 super geomagnetic storm, providing real-time, high-precision data crucial to understanding atmospheric responses to the space environment.

According to WANG Chi, Principal Investigator of CMP Phase II, the project exemplifies China's institutional strengths in mega-science. "By unifying global-scale monitoring, we are building a critical shield against space weather threats and offering innovative solutions to global scientific challenges," he said.

Building on this success, China is launching the International Meridian Circle Program (IMCP)—a 180-degree longitude monitoring chain, extending from 120°E to 60°W, enabling continuous, all-latitude observation of space weather. This initiative will address transnational challenges such as solar storms and geomagnetic disruptions, reflecting a commitment to a collaborative future in space exploration.