On March 13, 2024, China launched a pair of lunar satellites, DRO-A and DRO-B, from the Xichang Satellite Launch Center aboard a Long March 2C rocket equipped with a Yuanzheng-1S upper stage. The mission had been designed to place the twin spacecraft into a distant retrograde orbit around the Moon, with the goal of forming a three-satellite network alongside a previously launched spacecraft, DRO-L, in low Earth orbit. The objectives were multi-layered: to demonstrate intersatellite communication across Earth-Moon distances, to validate the utility of high lunar orbits that move opposite to the Moon’s orbital direction around Earth, and to further test hardware designed for extended operations in deep space. However, a malfunction in the upper stage led to one of the most complex spacecraft recovery efforts in recent history, executed under immense time constraints and engineering risk.
The launch anomaly caused the upper stage to fail its planned translunar injection. Instead of entering the intended transfer trajectory toward the Moon, DRO-A and DRO-B were left marooned in an elongated elliptical orbit around Earth, with an apogee, its farthest point from Earth, falling well short of what was required to escape Earth’s gravity and reach lunar orbit. To make matters worse, telemetry confirmed the satellites were spinning rapidly, completing a full rotation every 1.8 seconds. This high-speed spin not only jeopardized the structural stability of the joined spacecraft but also introduced the risk of critical systems failing due to sustained mechanical stress. Communication links were unstable, and the spacecraft had yet to deploy fully.
This situation triggered an urgent response from the mission team, which included engineers and researchers from the Innovation Academy for Microsatellites of the Chinese Academy of Sciences, as well as personnel from the Technology and Engineering Center for Space Utilization. The team began immediate consultations, building a complete systems profile of the satellites and initiating recovery procedures even as they continued to analyze telemetry. Their first move was to bring the spin under control. Utilizing the attitude control engines on DRO-B, operators remotely initiated a correction procedure that gradually slowed the rotational speed. Over the span of approximately 20 minutes, the spacecraft were brought to a stable attitude, a crucial step in preserving the onboard instrumentation and enabling further troubleshooting.
With the rotation halted, engineers turned their attention to an unexpected complication. Data showed anomalies in the solar array systems on both satellites. Deployment had either failed or resulted in deformation. The solar panels on both units were compromised. This posed a significant risk to the spacecrafts’ power budgets, as the satellites were dependent on solar generation for long-term operation. The team faced an extremely tight deadline. If they could not execute an initial propulsion burn within days, the opportunity to achieve distant retrograde orbit would vanish due to trajectory constraints and the narrowing launch window governed by Earth-Moon alignment.
What followed was an intense 40-hour planning session. Multiple gravitational influences had to be modeled in real time, including the competing effects of the Earth, Moon, and Sun. Further complications arose due to the extremely limited amount of fuel available to the satellites, as a significant portion of their delta-v capacity had been expected to be spent in the final stages of their original, now-aborted trajectory. With the added weight of both satellites still docked together, any burn would have to be precisely timed and conducted with strict attention to fuel efficiency.
The first maneuver took place on March 18. The engine burn lasted 1,200 seconds, a long-duration firing by satellite standards. This initial course correction succeeded in raising the apogee from 134,000 kilometers to 240,000 kilometers. While still short of lunar distance, it brought the pair closer to the trajectory required to complete additional maneuvers. Over the next four months, the satellites conducted four more burns. These were not merely brute-force thrusts but a combination of powered orbital corrections and gravity assists that took advantage of the dynamic environment between the Earth and Moon. This multi-phase transfer trajectory allowed the spacecraft to effectively spiral outward into the Moon’s gravitational influence while consuming as little fuel as possible.
Over this period, the spacecraft traveled an estimated 8.5 million kilometers, an extraordinary distance considering their small size and limited fuel margins. At one point during the mission, the satellites drifted to more than one million kilometers away from Earth. This placed them far beyond the Moon’s orbit but allowed mission control to take advantage of what is known as a low-energy capture trajectory, a concept drawn from orbital mechanics that permits lunar orbit insertion with significantly reduced propulsion requirements.
On July 15, 2024, the mission achieved its long-sought objective. The spacecraft entered into their targeted distant retrograde orbit around the Moon. This orbit, rarely used due to its complexity, is characterized by high-altitude paths that move counter to the Moon’s orbital motion around Earth. It provides an unusual level of orbital stability and is under active consideration by multiple national programs for future lunar infrastructure, including proposed gateways and relay stations.
In late August, the DRO-A and DRO-B satellites completed their physical separation. High-resolution cameras onboard captured images of each other for diagnostic purposes. These photographs revealed that the solar panels on DRO-A had bent to an angle nearing 90 degrees, likely during the spin period or during high-g maneuvers. DRO-B’s panels appeared even more heavily damaged, with one researcher describing them as resembling “broken wings.” The extent of the damage appeared to be cosmetic rather than functional, and telemetry confirmed that both satellites were still generating adequate power for mission operations. The images, released by Chinese media, also served to confirm the success of the attitude control procedures carried out months earlier.
The mission then moved into the operational phase. A central component of the plan was to test inter-satellite communication links, specifically K-band microwave transmissions, across the Earth-Moon distance. Using DRO-L in low Earth orbit as a relay node, engineers established a functional communication network between all three spacecraft. For the first time on record, satellites were able to directly track and communicate with each other across this range without relying exclusively on ground-based tracking stations. This represents a shift in how space-based infrastructure might be organized in the future. According to mission scientist Wang Wenbin, the accomplishment effectively transforms what would traditionally be a fixed, terrestrial tracking system into a mobile, spaceborne architecture. Instead of routing all signals through Earth-based stations, the satellites can now independently verify positions and synchronize data.
This system introduces new potential for navigation and coordination in deep space operations. The reduction of reliance on Earth stations could lessen transmission delays and improve real-time response capability for future missions. This also has direct implications for the eventual construction of lunar gateways, orbiting laboratories, and sustained surface operations, where autonomous or semi-autonomous networks could take on a central role in operational control.
Beyond its engineering contributions, the mission carries a payload for high-energy astrophysics research. The DRO-A satellite is equipped with an all-sky gamma-ray burst detector, a follow-on design to the system flown aboard China’s GECAM mission in 2020. Positioned in lunar orbit, the instrument offers a cleaner observational platform, free from many of the electromagnetic interferences that plague instruments in low Earth orbit. Researchers plan to use the data gathered to examine energetic cosmic phenomena that occur on short timescales. These include events such as neutron star mergers, black hole activity, and unknown transient events that emit gamma radiation over short periods.
The stability of the distant retrograde orbit further enables long-duration observational campaigns. Unlike low lunar orbits, which require constant adjustment due to gravitational irregularities in the Moon’s mass concentrations (mascons), the DRO offers a more passive environment that reduces the frequency of orbital corrections. This permits consistent data collection over weeks and months, contributing to more reliable datasets and fewer interruptions due to maneuvering.
The successful recovery of DRO-A and DRO-B stands as one of the more technically challenging feats of autonomous spacecraft navigation and rescue in recent decades. It reflects increasing competence in trajectory design, deep-space navigation, and satellite autonomy among Chinese aerospace institutions. It also offers practical demonstrations of how future missions can be salvaged or reconfigured when initial launch or orbital injection phases go awry. Rather than discarding the mission, operators relied on onboard redundancy, adaptive planning, and the robust engineering of the spacecraft themselves to bring about a successful recovery and redeployment.
No announcement has yet been made on the long-term plans for the satellites beyond their current operations, but the systems aboard suggest that the mission could remain productive well into 2025 and beyond. The communication protocols tested during this operation are expected to inform future standards for spacecraft interactions in cislunar space. Similarly, the experience gathered during the emergency response phase is likely to influence mission planning and fault-response procedures for future lunar and planetary missions.
There has been no external confirmation of whether the intersatellite tracking capabilities tested in this mission will be integrated into broader systems currently under development by China’s space agency. However, the ability to monitor and navigate spacecraft across lunar distances without exclusive reliance on Earth-based systems marks a strategic step forward. It allows for distributed command architectures and decentralized spaceflight operations, both of which are foundational for long-term habitation or commercial activities beyond Earth orbit.
This recovery and completion of objectives also reinforce growing interest in the use of distant retrograde orbits for upcoming lunar missions. The low delta-v requirements for station-keeping, combined with the high stability and unique observational vantage point, make DROs particularly attractive for scientific and logistical applications. Other space agencies, including NASA, have expressed intentions to deploy assets into DROs, especially for gateway-style missions. The Chinese satellites now serve as operational precedents for such plans.
