Developed by China Aerospace Science and Technology Corporation (CASC), a major contractor of the country's lunar exploration programs, the Chang'e 4 lunar probe is seen as a milestone in China's endeavor to explore the moon. It landed on the Von Karman crater in the South Pole-Aitken basin at 10:26 am on Jan 3.
It then sent back a picture of the landing site shot by one of the lander's monitor cameras through Queqiao, the first relay satellite in a halo orbit around Earth-Moon Lagrangian point L2, the world's first close-range image taken of the moon's far side.
The mission is mankind's first expedition to the moon's far side and includes the first relay communication between it and the Earth, and opened a new chapter in lunar exploration history.
The image shows Chang'e 4 probe's landing process. [Photo/sasac.gov.cn]
According to the China National Space Administration (CNSA), Chang'e 4's landing process started at 10:15 am when the spacecraft began descending from an orbit 15 kilometers above the lunar surface, following control signals from the Beijing Aerospace Control Center transmitted via China's Queqiao relay satellite. An engine was ignited to lower the craft's relative velocity from 1.7 km per second to close to zero, and the probe's altitude was adjusted to face the moon and descend vertically.
The probe made rapid position adjustments 6 to 8 kilometers above the moon. The descent then paused about 100 meters above the surface so the destination's inclination could be analyzed and any hazards could be detected at the preset landing site.
After an exact landing area was determined, Chang'e 4 slowly resumed its descent and touched down. Some 690 seconds later, Chang'e 4 landed at the Von Karman crater in the South Pole-Aitken basin, a feat recorded by a series of pictures shot by monitor cameras, the space administration said in a statement.
This picture is shot during Chang'e 4's landing. [Photo/sasac.gov.cn]
Chang'e 4 sends back this picture after its soft landing on the far side of the moon.
Shortly after the landing, the probe unfolded its solar arrays and antennas and established a high-speed data link through Queqiao. Even though a small satellite, Queqiao carries a deployable high-gain parabolic antenna with a diameter of 4.2 meters, the largest in the history of deep space exploration.
At 11:40 am, the monitor cameras on the probe' lander shot the world's first close-range photograph of the moon's far side and sent it back to the Earth through Queqiao.
Photo provided by the China National Space Administration on Jan 3, 2019 shows the first image of the moon's far side taken by China's Chang'e-4 probe. The place is where Chang'e 4's rover will be heading to roam and survey. [Photo/sasac.gov.cn]
The probe consists of two parts — a lander and a rover. The two carry eight mission instruments including two jointly designed by Chinese scientists and their counterparts in Sweden and Germany. It was designed based on its predecessor, the Chang'e 3, with some modifications.
The lander is equipped with topographic and landing cameras, a low-frequency radio spectrometer, and lunar lander neutrons and dosimetry from Germany.
The rover is installed with a panoramic camera, an infrared imaging spectrometer, radar measurement devices and an advanced small neutral atom analyzer from Sweden. Its advanced lunar penetrating radar is to produce the world's first geologic cross-section of the moon's far side.
Through positioning and patrol detection on the far side of the moon, the instruments will be used for launching low-frequency radio astronomy observation and research on the moon's topographic features, mineral composition and the superficial structure of its surface as well as the space environment such as neutron radiation levels and neutral atoms.
Scientists say that with the investigation into the far side of the moon, specifically the Von Karman crater, the Chang'e 4 mission will enable scientists to make new discoveries about the moon and deepen their knowledge of the early histories of the moon and the solar system.
The far side of the moon is a quiet and untapped place with no wireless signals, which is perfect for conducting low-frequency radio astronomical observation. The mission will provide possibilities for research on the sun, planets and celestial bodies outside the solar system and offer key materials for the research on the origin of stars and nebula evolution.
The China National Space Administration said it is willing to cooperate with space agencies, space science research institutes and science enthusiasts around the world to explore the mysteries of the universe. Chang'e 4's international payloads show that China is open to the world when it comes to scientific research and cooperation.
Next, Chang'e 4 will begin testing and fine-tuning its equipment through the Queqiao relay satellite and will wait for suitable conditions to release its rover with ground control, the space administration said.
(Executive editor: Li Shuling)