Chinese engineers have shared details of a unique deep space rescue operation. In the course of the mission, they managed to send a pair of experimental satellites DRO-A and DRO-B to the Moon.
The DRO-A and DRO-B vehicles were launched on March 13, 2024. They were to enter a deep retrograde orbit (DRO) around the Moon before connecting with the previously launched DRO-L satellite in low Earth orbit. The primary objective of the mission was to test inter-satellite communication technology and demonstrate the utility of DRO. DRO-A also carried a detector for monitoring gamma-ray bursts.
However, during the launch, the Yuanzheng-1 booster failed to fulfill its task and put the pair of vehicles into the specified orbit. They ended up in a highly elliptical Earth orbit with a much lower apogee than planned. Making matters worse, the bundle of satellites was spinning at a rate of one revolution per 1.8 seconds, threatening their structural integrity.
In this difficult situation, the mission specialists did a filigree job of rescuing the vehicles. First, they eliminated the spin using the DRO-B engines. Then, the team developed a rescue plan for the next 40 hours. At the same time, engineers had to take into account the complexity of orbital dynamics and gravitational disturbances from the Earth, Moon and Sun, as well as the extremely limited amount of fuel. Another problem was time. The team had only a few days in which they could perform the first maneuver and hope to reach the DRO.
The first critical engine run, which took place on March 18, lasted 1,200 seconds. It raised the apogee of the satellites’ orbit from 134,000 to 240,000 kilometers. Over the next four months, DRO-A and DRO-B performed four more orbital maneuvers, several additional course corrections, and used the moon’s gravity.
All these efforts were successful. On July 15, 2024, the satellites safely entered their designated orbits, having covered about 8.5 million kilometers. On August 28, the vehicles separated, after which they photographed each other. It turned out that the DRO-A solar panels were bent nearly 90 degrees due to spinning, and the DRO-B arrays looked like “broken wings” dangling from wires.
But despite all this damage, the power generated was enough to run the vehicles. Satellites has successfully established K-band microwave inter-satellite measurement links to DRO-L, creating an interplanetary satellite network that does not require ground stations.
According to Spacenews
