China's ambitious plans for Earth-moon infrastructure are progressing, with several recent missions demonstrating key technological advancements. The DRO-A and DRO-B spacecraft, launched in March 2024, successfully achieved lunar distant retrograde orbits (DRO) after a dramatic rescue following an upper stage failure. Their mission focused on testing communications, navigation, and orbital dynamics in this challenging environment.
Simultaneously, Tiandu-1, launched with the Queqiao-2 lunar relay satellite, reached lunar orbit and subsequently entered a 3:1 resonance orbit. This achievement, confirmed by amateur satellite tracker Scott Tilley, marks a significant step in China's plans for the Queqiao constellation. The China’s Deep Space Exploration Laboratory (DSEL) stated, “Its flight data will provide important support for technical research such as orbit maintenance and control, autonomous navigation, and navigation of spacecraft in complex gravitational environments.”
DRO-B, initially designed for DRO testing, is now navigating a 3:2 resonance orbit and exploring the Earth-moon Lagrange points L3, L4, and L5. This exploration is crucial for future infrastructure development in these gravitationally stable regions. However, Tilley's observations reveal that DRO-B's operation is intermittent, potentially due to solar panel damage sustained during the launch mishap. This highlights the challenges inherent in these complex missions.
The success of Tiandu-1's 3:1 resonance orbit is significant, though not unprecedented. NASA's IBEX spacecraft has operated in a similar orbit. However, DSEL's claim that Tiandu-1 was the first to achieve this specific orbit has been debated. Furthermore, observations of Tiandu-2 suggest potential issues, with Tilley noting unusual rotation. These unexpected challenges, while not negating the significant achievements, underscore the difficulties of deep-space operations.
China's ongoing lunar missions, including the upcoming Chang'e-7 and Chang'e-8 missions targeting the lunar south pole, will rely heavily on the infrastructure being developed and tested by these precursor missions. The successes and challenges encountered by these spacecraft provide valuable lessons for the future of lunar exploration.