China has successfully established the world’s first three-satellite constellation in the Earth-moon region using a distant retrograde orbit (DRO), marking a significant milestone in space science and technology. Developed by the Chinese Academy of Sciences (CAS), the project features a trio of satellites with stable inter-satellite communication and measurement links, according to information shared with the Global Times on Wednesday.
This breakthrough sets the stage for China’s broader ambitions in utilizing and exploring the cislunar space — a vast domain that stretches up to 2 million kilometers from Earth. According to CAS, this region’s spatial volume is more than a thousand times that of Earth’s immediate orbital space, offering immense potential for scientific advancement, resource development, and interplanetary travel.
The project began in 2017 with foundational research and technology development. In early 2022, a pilot initiative was launched to build a large-scale constellation aimed at studying the unique properties and practical uses of the DRO. By 2024, China launched three satellites as part of the program — DRO-A, DRO-B, and DRO-L.
DRO-A and DRO-B were launched in March 2024 and successfully entered their target orbits by July. DRO-L, launched in February 2024 into a sun-synchronous orbit, conducted experiments that complemented the constellation. By August 2024, the three satellites were operating as a unified system in cislunar space.
According to the Technology and Engineering Center for Space Utilization (CSU) under CAS, the DRO-A satellite will remain permanently in the distant retrograde orbit, while DRO-B will maneuver within the Earth-moon space to perform various tasks.
The mission has already yielded several world-firsts. Chinese scientists utilized an innovative low-energy trajectory design, opting for longer travel times in exchange for increased payload capacity and fuel efficiency. The approach allowed the satellites to complete Earth-moon transfers and DRO insertions using just 20% of the fuel typically required — marking the first successful low-energy DRO insertion globally.
Another critical achievement includes the successful establishment of a 1.17-million-kilometer K-band microwave communication and measurement link between the satellites, a technological leap in building large-scale inter-satellite networks in deep space.
The constellation also supports astrophysical studies, such as detecting gamma-ray bursts, and has trialed advanced space technologies, including atomic clocks and autonomous navigation systems. One particularly notable advancement was the validation of a satellite-to-satellite orbit determination method. By tracking each other rather than relying on Earth-based ground stations, the satellites achieved navigation accuracy in just three hours that traditionally took over two days.
“This marks the first time worldwide that orbit determination has been verified through satellite-to-satellite tracking,” explained Wang Wenbin, a researcher at CSU. “It’s like transforming a ground station into a mobile satellite, enhancing both flexibility and efficiency.”
This new technique is expected to greatly improve orbit navigation and timing for future missions in cislunar and deep space environments, significantly reducing operational costs and improving autonomy.
Looking ahead, the constellation will support China’s lunar exploration initiatives by offering real-time navigation services, precise timing for lunar surface operations, and reliable communication links for transmitting mission-critical data. The unobstructed vantage point of the DRO also makes it ideal for managing communication with spacecraft on or near the moon.
With this pioneering constellation now in place, China is not only expanding its presence in cislunar space but also laying the technological foundation for future large-scale exploration and commercialization of the solar system.
