China launches relay satellite for Earth-Moon communications
China yesterday launched a new relay satellite to provide EarthMoon communications services, a key step for its future lunar exploration missions such as retrieving samples from the far side of the moon and exploring the lunar south pole region.
A Long March-8 rocket, carrying the satellite dubbed Queqiao-2, or magpie bridge-2, soared into the sky at 8:31am from the Wenchang Space Launch Site in south China’s Hainan Province.
After 24 minutes of flight, the satellite separated from the rocket, and entered the planned Earth-Moon transfer orbit with the perigee at 200 kilometers and the apogee at 420,000km. The satellite’s solar panels and communications antennae were unfolded, according to the China National Space Administration.
“Today’s launch has laid a good foundation for the ensuing flight control of the Queqiao-2 relay satellite,” said Ge Ping, deputy director of the CNSA’s Lunar Exploration and Space Program Center.
However, the successful launch is only the first step of the Queqiao-2 mission. A series of important maneuvers such as midway trajectory correction, decelerating near the moon and orbit adjustment will be carried out before Queqiao-2 enters its target elliptical orbit around the moon to become the world’s second relay satellite deployed beyond Earth orbit.
After that, communications tests will be carried out to determine whether the Queqiao-2 relay satellite has the ability to support the sample collection mission from the far side of the moon, Ge said.
According to a Chinese folktale, Zhi Nyu, the seventh daughter of the Goddess of Heaven, and her beloved husband, Niu Lang, a humble cowherd, found their love forbidden and were 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.
Hence, the satellite’s name, 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.
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 moon’s far side 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 2018 to a halo orbit around the second Lagrangian (L2) point of the Earth-Moon system.
Thanks to the communications support and data transmission from this relay satellite, China later sent the Chang’e-4 probe to the Von Karman Crater in the South Pole-Aitken Basin, realizing the first-ever soft landing and roving on the far side of the moon at the start of 2019.
Since the first Queqiao satellite has exceeded its designed lifespan, Queqiao-2 will take over the communications relay services for Chang’e-4.
Compared with the first Queqiao, the new satellite boasts enhanced functionality, innovative features and intricate designs. It also carries multiple instruments for scientific exploration.
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, the CNSA said.
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, according to the CNSA.
(Xinhua)
Today’s launch has laid a good foundation for the ensuing flight control of the Queqiao-2 relay satellite.
Ge Ping Deputy Director of the CNSA’s Lunar Exploration and Space Program Center.