Beijing, January 6 (CNBC) -- According to the Voice of China's "News Hyperlink" of the Central Radio and Television Corporation, on January 3, the "Chang'e 4" ushered in the third anniversary of the moon.
Three years later, what tasks have been accomplished by the Queqiao relay satellite, the Chang'e-4 lander and the Yutu-2 lunar rover, known as the "Moon Back Trip Trio"? What else is there to do?
"Chang'e-4" probe launched into the air (Source: CCTV news client)
"Queqiao" relay satellite: the main business part-time grasps with both hands
Xie Renjiang, a member of the China Association of Popular Science Writers and the founder of the Shepherd Astronomy Forum, introduced that the rotation speed of the moon is the same as that of the revolution, which makes it always face the earth on the same side, so that the moon has a front and back side. How to transmit the signal from the back of the moon to the earth has also become a major obstacle for human exploration of the back of the moon. The Queqiao relay satellite serves as a communication and data relay station between the Earth and the Moon, which is like building a bridge between the Earth and the back of the Moon.
"Queqiao" arrived at the post earlier than the other two partners - on May 21, 2018, "Queqiao" was launched at the Xichang Satellite Launch Center and began service. It is precisely because of the "Queqiao" that the landing and detection work of "Chang'e-4" can be carried out normally.
"Queqiao" is located on the second Lagrange point of the Earth-Moon connection, which can directly establish contact with the earth, and can also achieve two-way communication with the "Chang'e 4", directly receiving the signal sent by the "Chang'e 4" from the far side of the moon, amplifying it, and then launching it to the earth.
Every month, Chang'e-4 is dormant for about half the time, when Queqiao does not need to relay communication work, it will do "part-time". Scientific detection is carried out by using its own low-frequency radio detector.
"Chang'e 4" lander: self-heating, will grow cotton
The lander is equipped with a number of scientific instruments for experiments and detection work.
The Yutu-2 rover panoramic camera images the Chang'e-4 lander (Source: China National Space Administration)
This is a biological growth and cultivation experiment, and the cultivation content is cotton seeds. Less than half a month after landing, the lander "planted cotton" on the lunar surface. The seed was successfully sprouted, becoming the first plant sprout planted by humans on the moon.
In addition, the lander has also probed some radiation doses on the lunar surface. There is no atmosphere on the lunar surface, and much of the cosmic ray radiation reaches the lunar surface directly. For the manned mission to be carried out later, only by understanding the radiation on the lunar surface can we know how people on the moon can avoid radiation damage.
Interestingly, "heating" was also installed on the lander. Temperatures on the far side of the moon are very low, as low as minus 190 degrees Celsius, which can freeze and make the equipment unable to work. The Chang'e-4 lander is equipped with a Chinese-developed isotope power supply that generates heat when radioactive isotopes decay, providing heat for the lander.
"Yutu-2" lunar rover: walk a kilometer and discover the "mysterious hut"
In three years, Yutu-2 has walked nearly a kilometer on the far side of the moon. It's like a fully autonomous off-road vehicle, and while it's small — 1.5 meters long, 1 meter wide, 1.1 meters high, and weighing 140 kilograms — it has advanced artificial intelligence technology to handle a variety of terrains.
"Chang'e-4" lander surveillance camera C took the "Yutu-2" rover on the lunar surface image (Source: China National Space Administration)
"Yutu-2" has an intelligent control system, which can perceive the surrounding environment and choose the forward route, not only can avoid obstacles autonomously, but also once trapped, as long as a wheel can land, it can get out of trouble.
Yutu-2 is currently the longest working lunar rover on the lunar surface. It is only designed to last three months, but has been working for three years and has been in service far beyond its deadline. However, the "Yutu II" that has been in service for a long time is not only in good condition, but also had a surprise discovery not long ago. During the ring photography, the "Jade Rabbit II" found an abrupt cube about 80 meters away, like a mysterious hut on the back of the moon. Considering the speed of the "Jade Rabbit II", the mystery of the "Mysterious Hut" may not be solved until several months later.
"Queqiao", "Chang'e", "Jade Rabbit", "Moon Back Business Trip Trio" all have romantic names, which are the imagination and pursuit of the moon for thousands of years in Chinese. Now, China's lunar exploration project is trying to peek into the mystery behind this romantic imagination. Chang'e 5 has retrieved soil samples from the moon, and three lunar missions are planned to be implemented in the next decade: Chang'e VI, Chang'e VII and Chang'e VIII.
Producer: Guo Jing
Reporter: Hejia
Editor: Marius Peng Yuji