China’s team behind the rescue of a pair of lunar satellites has revealed the challenges they faced in salvaging the mission. Initially launched on March 13, 2024, to send the DRO-A and DRO-B spacecraft into distant retrograde orbit (DRO) around the moon, an anomaly experienced by the mission’s Yuanzheng-1S upper stage left the satellites in a highly elliptical Earth orbit.
The team eliminated the spin of the satellites using the DRO-B satellite attitude control engines over 20 minutes. However, issues with both satellites’ solar arrays needed addressing next. The rescue plan required considering orbital dynamics and gravitational perturbations from the Earth, moon, and Sun, along with limited fuel. The deadline was mere days away.
The first critical engine burn on March 18 lasted 1,200 seconds, raising their apogee to 240,000 kilometers. Over the next four months, the satellites carried out four orbital maneuvers, gravity assists, and additional trajectory corrections.
Finally, on July 15, 2024, the DRO-A and DRO-B satellites safely reached their intended lunar orbit, traveling around 8.5 million kilometers. The satellites separated successfully on August 28. They then imaged each other, revealing bent solar panels.
The pair established K-band microwave intersatellite measurement communication links with DRO-L, verifying a three-satellite network across the Earth-moon distance. According to CSU researcher Wang Wenbin, this achievement enables tracking of satellites using spacecraft instead of ground stations. This breakthrough paves the way for future technological advancements in space exploration.
The DRO-A satellite carries an all-sky detector to monitor gamma-ray bursts, while China aims to utilize the long-term stability of the mission for fundamental scientific research.
Source: https://spacenews.com/mission-team-details-complex-rescue-of-chinese-lunar-spacecraft