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嫦娥四号在月球背面发现了啥?China's Chang'e-4 makes landing on Moon's far side

CGTN 2020-01-06

↑戳视频直击落月瞬间


1月3日10时26分, 嫦娥四号探测器成功着陆在月球背面,并通过“鹊桥”中继星传回了世界第一张近距离拍摄的月背影像图,揭开了古老月背的神秘面纱。


此次任务实现了人类探测器首次月背软着陆、首次月背与地球的中继通信,开启了人类月球探测新篇章。


China's Chang'e-4 probe successfully landed on the far side of the Moon at 10:26 a.m. BJT Thursday. This is the first ever soft-landing on this previously uncharted area.


The dark side is never visible from the Earth due to a phenomenon called tidal locking. But the probe sent back the world's first close picture of the Moon's far side via the relay satellite Queqiao (Magpie Bridge) which is operating in the halo orbit around the second Lagrangian (L2) point of the Earth-Moon system.


世界第一张

“嫦娥四号”近距离拍摄的月背影像图↓

The south side of the landing site on the far side of the Moon /CNSA Photo


The Chang'e-4 – which includes a lander and a rover – is now expected to study the mineral composition and shallow lunar surface structure of the Moon's far side, as well as perform low-frequency radio astronomical observation.


It will be a key step in revealing the mysterious side of the Moon, which never faces the Earth. 


An image captured during the landing process of Chang'e-4 lunar probe /CNSA Photo


The exact landing area is called Aitken Basin's Von Karman crater, and it is about 24,000 kilometers across and 13 kilometers deep. Chinese scientists believe the spacecraft's landing on this huge crater would enable them to collect some new information about the Moon's mantle, which is the name for the layer below the surface.


One of the key challenges and targets of the project is to validate communication technology via a relay satellite. The probe is communicating with Earth via the Queqiiao relay satellite, which was launched in last May to enable communication between the ground controllers and the Chang'e-4 probe.


An image captured after the probe's soft landing /CNSA Photo


Several different scientific programs were developed for the mission by Chinese universities, and there are also four international payloads jointly developed by scientists from Germany, Sweden, the Netherlands, Saudi Arabia and China. According to the China National Space Administration, over the next few months, they will conduct all these experiments accordingly.


The Chang'e-4 probe blasted off nearly a month ago on December 8, 2018, from southwest China's Xichang Satellite Launch Center.


CGTN infographic


A Moon detector


We always see the same side of the Moon, and its far side remains invisible as the Moon is tidally locked to the Earth, rotating at the same rate that it orbits our planet.


It is not an easy process for the probe to make the soft landing.


Composed of a lander and a rover, the probe will detect topography, material composition and the shallow structure of the landing and inspection areas, and conduct the world's first lunar-based low-frequency radio astronomical observation, according to Sun Zezhou, chief designer of Chang'e-4 mission.


With the payloads, the probe will carry out research and environmental detection on the lunar surface.


"In terms of both engineering and scientific significance, the Chang'e-4 mission is the most-anticipated one in the international scientific community in 2018," said Wu Yansheng, president of China Aerospace Science and Technology Corporation (CASC). "It will leave an indelible mark on China's scientific and technological development."


CGTN infographic


Why land on this basin?


The destination for Chang'e-4 probe is the Von Kármán crater in the South Pole-Aitken (SPA) basin, a huge and old impact crater on the far side (the southern hemisphere) of the Moon.


It will play a significant role in helping people learn more about the Moon.


The SPA basin is so far the largest known impact basin in the solar system, stretching from the south pole to Aitken crater at the other end, just as its name suggests. As deep as 13 kilometers, it is also the deepest impact basin on the Moon, which means that the impact probably excavated material deep in the lunar crust and even down to the mantle. The basin may potentially provide samples for the study of the Moon's interior composition.


As large and deep as it is, the SPA basin is also one of the oldest basins on the Moon. Formed about 3.92 billion years ago, it is a crucial site to study the Moon's 4.5-billion history.


The 186-kilometer-diameter Von Kármán crater, located at the middle part of the basin, is of high scientific interest.


The crater is typical in geomorphic type, material composition and geological age and is rich in thorium, iron oxide, and titanium dioxide. The abnormal spatial distribution of the material composition may provide clues to volcanic and lunar crust activities in the region, and therefore helpful to the study of the origin of lunar mantle basalt.


Meanwhile, the southern terrain of the crater is relatively flat, providing favorable conditions for the probe's landing.


Exploration of Moon and deeper space


Both the Chang'e-4 mission and the future exploration of the north and south poles of the Moon belong to China's 4th-phase lunar exploration, said Ye Peijian, an expert with the China Aerospace Science and Technology Corporation Fifth Academy.


The main missions of the 4th phase include exploring the north and south poles of the moon with the aid of robots, establishing unmanned lunar research stations, and integrating the lander, robot and staff on the ground for better cooperation.


"During the fourth lunar exploration phase, the Chinese probe will land on more places on the Moon, explore more things, and involve more robots," said Ye.


China's space exploration will expand from the Moon to the deeper universe, and four major tasks can be expected according to China National Space Administration, including launching a probe to the Mars, sampling and taking back Martian surface materials, conducting an asteroid exploration, and planning a probe to Jupiter. 


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