China has successfully deployed the world’s first three-satellite constellation in a distant retrograde orbit (DRO) within the Earth-moon space region, achieving a significant milestone in space science and technology. The breakthrough was confirmed by the Chinese Academy of Sciences (CAS), the developer behind the mission.
According to CAS, the trio of satellites—DRO-A, DRO-B, and DRO-L—has established stable inter-satellite communication and measurement links, forming a fully functioning constellation as of August 2024. This development marks a world first, and lays the groundwork for China's ambitions in cislunar exploration and space science innovation.
The Earth-moon space region, or cislunar space, extends up to 2 million kilometers from Earth and has a volume more than 1,000 times larger than Earth's orbital space. CAS emphasized the region’s strategic value for lunar resource extraction, deep space exploration, interplanetary transport, and long-term human presence beyond Earth.
Initial research and technology development in the region began in 2017, with a pilot satellite constellation project launched in February 2022. By mid-2024, DRO-A and DRO-B had entered their operational orbits, while DRO-L began experiments in a sun-synchronous orbit. The satellites now work together to explore the DRO’s potential and demonstrate new technological capabilities.
One of the constellation's most notable achievements is its low-energy transfer and insertion into the DRO—accomplished with just 20% of the fuel typically required. This was made possible by an innovative approach: extending flight time in exchange for increased payload capacity and greater operational flexibility. The method represents the first successful low-energy DRO insertion globally and has the potential to drastically reduce the cost of accessing cislunar space.
Another major feat was the verification of a 1.17-million-kilometer K-band inter-satellite microwave link, setting a new record in space communications. This development overcomes a major hurdle in establishing large-scale satellite networks beyond Earth's orbit.
In the realm of space science, the mission has also contributed to astrophysical research, such as detecting gamma-ray bursts, and has tested advanced space technologies, including atomic clocks. One of the most groundbreaking results has been a new orbit determination method using satellite-to-satellite tracking rather than traditional ground stations. In just three hours, this system achieved the same level of accuracy as two days of ground-based tracking.
“This marks the first time that satellite-based orbit determination has been successfully verified instead of relying on ground stations,” said Wang Wenbin, a researcher at CAS's Technology and Engineering Center for Space Utilization. “It’s akin to transforming a ground station into a satellite and placing it in low-Earth orbit, opening a new pathway for deep space navigation and timing.”
The satellite network is also poised to play a crucial role in China’s future lunar missions by enabling autonomous navigation, rapid orbit determination, and precise time synchronization for both orbiters and surface infrastructure. The DRO’s distant, unobstructed location from both Earth and the Moon makes it ideal for secure communication, especially for critical or emergency data transmissions.
Chinese researchers see the constellation as a cornerstone for scaling up commercial and scientific activities in cislunar space. It not only advances China’s space capabilities but also provides new tools for the global exploration of the solar system.
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