On March 15, 2025, China launched satellites DRO-A and DRO-B on a Long March-2C carrier rocket with the Yuanzheng-1S upper stage. The satellites did not reach their intended orbit due to a failure of the upper stage, ending up closer to Earth and spinning uncontrollably. After a 123-day rescue operation, engineers from the Center for Space Utilization Technology and Engineering Development (CSU) used the gravitational forces of Earth, the Moon, and the Sun to correct the trajectory.
The satellites' solar panels were damaged, preventing autonomous orbit correction. A team led by Zhang Hao calculated the trajectory, while a second team controlled the engines for stabilization. The gravitational maneuver placed DRO-A and DRO-B on their correct orbits, preventing their destruction upon entering the atmosphere.
The satellites are integrated with DRO-L into a navigation network that reduces the time for space probe positioning from 2–3 days to three hours. This will enable autonomous control of spacecraft beyond Earth orbit, supporting lunar missions in 2030 and the construction of ILRS.
"The gravitational maneuver used in this mission could become a standard for orbit correction under limited resources. The new navigation system will improve the accuracy and autonomy of space flights," said Mao Xinyuan from CSU.