In a quiet expanse of space roughly 400,000 kilometers from Earth—just beyond the Moon’s orbit—three Chinese satellites are silently rewriting the rules of deep-space exploration.
For the first time in history, a functioning constellation now operates in distant retrograde orbit (DRO), a gravitationally stable ‘parking spot’ in the Earth-Moon system. This feat could redefine humanity’s approach to long-term lunar habitation, interplanetary travel, and the commercialization of cislunar (Earth-Moon) space.
The constellation—comprising DRO-A, DRO-B, and DRO-L satellites—marks a critical leap in cislunar infrastructure development and affirms China’s ambitions to lead in lunar and deep-space activities.
Developed by the Chinese Academy of Sciences (CAS), this pioneering project has not only set a global benchmark but also unlocked groundbreaking efficiencies in fuel consumption, navigation, and communication—capabilities that could make large-scale space infrastructure economically viable.
Key Highlights
- Supports future lunar missions, time-sync systems, and emergency data relay from deep space
- World’s first three-satellite constellation in Distant Retrograde Orbit (DRO)
- Satellites used just one-fifth of traditional fuel for orbit insertion, slashing deep-space mission costs.
- Million-kilometer communication: Verified a 1.17-million-km inter-satellite microwave link, overcoming a major bottleneck.
- Revolutionary navigation: Achieved satellite-to-satellite tracking, eliminating reliance on ground stations for orbit determination.
- Strategic implications: Supports lunar exploration, deep-space missions, and future commercial activity in cislunar space.
What is Earth-Moon Space
Earth-moon space—also known as cislunar space—refers to the massive, underutilized region extending up to 2 million kilometers from Earth. Compared to traditional Earth orbits, this three-dimensional area is more than 1,000 times larger in volume, offering immense potential for navigation, communication, and deep-space mission staging.
What Is Distant Retrograde Orbit (DRO)?
At the heart of this new frontier lies the Distant Retrograde Orbit (DRO), a fuel-efficient orbit situated approximately 310,000 to 450,000 kilometers from Earth. DRO provides high orbital stability with minimal fuel requirements, making it ideal for hosting satellites that support lunar missions, serve as data relays, or enable interplanetary travel. Its low-energy feature and stability makes it ideal as a “space hub”—a potential staging point for future missions to the Moon, Mars, and deep space.
The Mission: From Rescue to Revolution
The journey of CAS’s strategic “Earth-Moon Space DRO Exploration” program was anything but smooth. Launched in March 2024, the DRO-A and DRO-B satellites faced near-disaster when an upper-stage rocket anomaly left them stranded in the wrong orbit.
In what engineers described as a ‘life-or-death’ moment for the mission, the satellite team undertook emergency orbital maneuvers over an 8.5-million-kilometer journey. “After a journey of 8.5 million kilometers, the DRO-A/B dual-satellite combination ultimately reached its designated orbit,” said Zhang Hao, a researcher at CAS’s Technology and Engineering Center for Space Utilization (CSU), who participated in the rescue.
The constellation was officially formed on August 28, 2024, when all three satellites—DRO-A, DRO-B, and the earlier-launched DRO-—were synchronized in orbit, establishing robust K-band microwave inter-satellite communication links.
Why this breakthrough matters
1. Fuel Efficiency redefines Deep-Space Access
Traditional deep-space missions require enormous fuel reserves, but China’s team engineered a radical solution. The satellites completed Earth-moon transfer and achieved low-energy DRO insertion using only one-fifth of the fuel required by traditional methods, according CAS revealed.
This low-energy insertion drastically cuts costs, making frequent missions to cislunar space feasible, opening up new avenues for large-scale development and utilization.
2. Satellite-to-Satellite Navigation
Historically, spacecraft relied on ground stations for tracking—a slow, expensive process. Now, China has flipped the script.
“This achievement marks the first time internationally that orbit determination was verified using satellite-to-satellite tracking rather than ground stations,” said Wang Wenbin, a CSU researcher. “It’s like turning a traditional ground station into a satellite and placing it in a low-Earth orbit. Using just three hours of inter-satellite data, the team matched the precision of two days of ground tracking—a leap that could streamline future missions to the Moon and beyond.
3. 1.17 million-kilometer Communication achieved
The constellation successfully verified a 1.17-million-kilometer K-band microwave communication link—marking a world first. This breakthrough demonstrates that stable, long-distance communication in deep space is feasible, potentially enabling real-time data relay for lunar bases or Mars missions.
What’s next for Earth-Moon Space?
This constellation isn’t just a technological flex—it’s an operational infrastructure designed to support future crewed lunar missions, autonomous navigation, data relay systems, and time synchronization for lunar surface operations.
The DRO serves as a “natural space hub connecting Earth, the Moon and deep space,” said Wang. It also provides an efficient solution for orbit determination, navigation, and timing across various cislunar orbits, supporting the future expansion of large-scale commercial activity in cislunar space.
With the constellation now operational, the research team intends to deepen studies of DRO and other complex cislunar orbits. Future missions will explore the lunar space environment’s laws and long-term orbital behavior—knowledge crucial for sustainable extraterrestrial operations.
As spacefaring nations eye the Moon, Mars, and beyond, China’s latest achievement signals a powerful message: the race for cislunar dominance is not just heating up—it’s orbiting ahead.
