BEIJING, April 12 (Xinhua) -- The Queqiao-2 satellite has completed in-orbit communication tests, with its platform and payloads working normally, according to the China National Space Administration (CNSA) on Friday.
Queqiao-2 is the second satellite of the Queqiao data relay satellite series. The satellite not only has the capability to transmit data for lunar probes, but also carries payloads such as an extreme ultraviolet camera and an array neutral atom imager to conduct scientific exploration missions.
With a design life of five years, the first Queqiao has been in orbit for nearly six years, having been in extended service since last year. To support current and future lunar exploration missions, such as the incoming Chang'e-6 mission, China launched Queqiao-2 on March 20 to be a better replacement.
Mounted with more payloads, Queqiao-2 weighs 1.2 tonnes, nearly three times of Queqiao's 425 kg. Queqiao-2 has a design life of eight years, three years longer than that of Queqiao.
Queqiao-2 uses highly elliptical lunar frozen orbit which was only about 300 km away from the moon at the closest point. Queqiao, however, orbits around the second Lagrangian (L2) point of the Earth-Moon system, which is about 65,000 km from the moon. The closer distance will make data transmission of Queqiao-2 more efficient, clearer and more complete.
Unlike Queqiao, which operates independently, Queqiao-2 will orbit the moon in formation with Tiandu-1 and Tiandu-2 communication and navigation technology test satellites, which were launched together with Queqiao-2. Together they will be able to verify high-precision lunar orbit determination technology and conduct tests for future missions.
After Queqiao-2 enters the planned orbit, the two Queqiao satellites can also work together to transmit data between Earth and moon for Chang'e-4 and Chang'e-6.
Additionally, Queqiao-2 will provide communication services for Chang'e-7, Chang'e-8 and future lunar exploration missions. It will also carry out tasks such as scientific exploration and technology verification.
The name of the satellite series, Queqiao, embodies China's hope that the relay satellite could serve as a vital communication link between Earth-based controllers and the mysterious far side of the moon.
According to a Chinese folktale, Zhi Nyu, the seventh daughter of the Goddess of Heaven, and her beloved husband, Niu Lang, a humble cowherd, were forbidden from being together and separated to opposite sides of the Milky Way. Moved by their plight, magpies intervened, creating the Queqiao bridge with their wings on the seventh night of the seventh month of the lunar calendar, allowing the couple to reunite for just one day each year.
Since the moon's revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far side or "dark side" of the moon. This term doesn't refer to darkness but rather to the mystery shrouding the moon's largely unexplored terrain.
Due to its special environment and complex geological history, the far side of the moon stands as a prime destination for scientific and space exploration. In order to explore the moon's far side, China sent the first Queqiao relay satellite in May 2018 to a halo orbit around L2 point of the Earth-Moon system. ■
