A Long March-8 rocket, carrying the relay satellite Queqiao-2 for Earth-Moon communications blasts off at the Wenchang Space Launch Center in south China's Hainan Province, March 20, 2024. [Photo/Xinhua]

The Queqiao-2 satellite has recently completed in-orbit communication tests, with its platform and payloads working normally, according to the China National Space Administration (CNSA) on Friday.

The functions and performance of Queqiao-2 meet mission requirements, and it can provide relay communication services for the fourth phase of China's lunar exploration project and future lunar exploration missions of China and other countries, said the CNSA, announcing the Queqiao-2 mission a complete success.

The satellite successfully completed a communication test on April 6 with Chang'e-4, which is now carrying out an exploration mission on the far side of the moon. From April 8 to 9, it conducted communication tests with the Chang'e-6 probe, which is yet to be launched.

Queqiao-2 was launched on March 20 and entered its target highly elliptical orbit on April 2 after midway correction, near-moon braking and orbital maneuver around the moon.

Two communication and navigation technology test satellites, Tiandu-1 and Tiandu-2, were sent into space together with Queqiao-2. They entered their target circumlunar orbits on March 29 and separated with each other on April 3. They are now conducting a series of tests on communication and navigation technology.

Queqiao-2, Tiandu-1 and Tiandu-2 all use a highly elliptical lunar frozen orbit as their target orbits. This kind of orbit is stable, ensuring the spacecraft travels with the minimum of trajectory deviation.

This orbit can bring many advantages to Queqiao-2. Compared with Queqiao, which was launched in 2018 for Earth-Moon relay communications, the orbit of Queqiao-2 is closer to the moon, which greatly improves the communication rate of data transmission.

Compared with Queqiao, which orbits around the second Lagrangian (L2) point of the Earth-Moon system, Queqiao-2 has also significantly improved its communication coverage on the south pole region of the moon.

This orbit also helps the satellite save fuel, meaning that Queqiao-2 can stay in this orbit for a long time with very little fuel.

Queqiao-2 will provide relay communication services for the Chang'e-4 lunar probe and the Chang'e-6 mission in the future as planned, and carry out scientific exploration at an appropriate time.

The deployment of the Queqiao-2 relay satellite is a key step for China's future lunar exploration missions, including Chang'e-6, Chang'e-7 and Chang'e-8.

The landing and sample collection sites of China's moon missions in the coming years are mainly in the lunar south pole region or on the far side of the moon. A more powerful relay satellite with more functions is necessary to provide communications and data transmission services for the missions.

Chang'e-6 is scheduled for launch in the first half of 2024, while Chang'e-7 will be launched around 2026, and Chang'e-8 around 2028. Chang'e-7 and Chang'e-8 will form the basic model of a lunar research station to carry out lunar environment exploration, according to the CNSA.