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BEIJING, Jan. 6 (Xinhua) – The Chinese probe Chang & # 39; e-4 has begun exploration on the other side of the moon thanks to the relay satellite that provides the communication link with the ground control .
The relay satellite, named Queqiao, which means Magpie Bridge, according to a Chinese legend, was launched on May 21, 2018 and became the first communication satellite operating in orbit around the second Lagrangian point (L2) of the Earth system -Lune, nearly 500 000 km from the land.
The maximum distance between the satellite and the Chang-e-4 probe on the other side of the moon is 79,000 km. The satellite processes the data from the probe and transmits it to Earth, said Sun Ji, a satellite designer at the China Academy of Space Technology.
The satellite can remain in its orbit for a long time because of its relatively low fuel consumption, the gravity of the Earth and the Moon balancing its orbital motion, said Zhang Lihua, chief designer of the satellite.
In orbit, he can "see" the Earth and the hidden side of the Moon. From Earth, the orbit looks like a halo on the moon, Zhang said.
The concept of deploying a relay satellite in the orbit of the halo was first introduced by US space experts in the 1960s, but by Chinese space engineers.
"We will let Queqiao run for as long as possible." It could also provide a communication to probes from other countries if they intend to explore the hidden face of the moon for the duration of satellite life, "said Ye Peijian, academician of the Chinese Academy of Sciences and a senior space expert.
"And it will be a Chinese contribution to the world," said Ye.
The relay satellite will also be used for scientific and technological experiments.
It has a low frequency radio spectrometer, developed jointly by Dutch and Chinese scientists, to help astronomers "listen" to the depths of the cosmos.
It also carries a reflector developed by Sun Yat-sen University in Guangdong Province, southern China, to perform the world's longest laser telemetry test between the satellite and a satellite. observatory on the ground.
The researchers hope to use satellite cameras to capture asteroids striking the back of the moon, Sun Ji said.
"It's extremely difficult, but we hope to try," Sun said.
To control the cost of the Chang-e-4 mission, the relay satellite was designed to be relatively small, weighing around 400 kg.
Chinese experts have designed several antennas, including an umbrella shaped almost 5 meters in diameter.
"We have learned from textile technologists and watchmakers in the development of wire mesh and ribs of the antenna," Zhang said.
"It has to withstand temperature changes of over 300 degrees Centigrade, and we've had countless experiments doing that."
His team had only 30 months to develop the satellite, which put them under enormous pressure.
To promote the public interest in space exploration, the National Space Administration of China invited people to write their space and lunar exploration wishes, and the relay satellite bears the names tens of thousands of participants and their messages.
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